Stye &<&£?& ^ibruritB Jfartlf Carolina js>tatc Jlntuerstt^ ®l|tB book faas presenteb bg James R. Troyer £■& *t^-2<7-'?-Z- INTRODUCTION STRUCTURAL AND SYSTEMATIC BOTANY, AND VEGETABLE PHYSIOLOGY, BEING A FIFTH AND REVISED EDITION OF THE BOTANICAL TEXT-BOOK, ILLUSTHATED WITH OVER THIRTEEN HUNDRED WOODCUTS. By ASA GRAY, M.D., FISHER PROFESSOR OF NATURAL HISTORY IN HARVARD UNIVERSITY. NEW YORK: IVISON, PHLNNEY, & CO., 48 & 50 WALKER STREET. CHICAGO: S. C. GRIGGS & CO., 39 & 41 LAKE STREET. PHILADELPHIA: SOWER, BARNES, & CO., AND J. B. LLPPINCOTT & CO. BOSTON : BROWN, TAGGARD, & CHASE. CINCINNATI : MOORE, WILSTACH, KEYS, & CO. SAVANNAH : J. M. COOPER & CO. NEW ORLEANS : BLOOMFIELD, STEEL, & CO. ST. LOUIS : KEITH & WOODS. DETROIT : F. RAYMOND & CO. 1860. Entered according to Act of Congress, in the year 1857, by IVISON AND PHINNEY. in the Clerk's Office of the District Court for the Southern District of New York. University Press, Cambridge : Electrotyped and Printed by Welch, Bigelow, & Co. PREFACE. This compendious treatise is designed to furnish classes in the higher seminaries of learning, colleges, and medi- cal schools, as well as private students generally, with a suitable text-book of Structural and Physiological Botany, and a convenient introduction to Systematic or Descriptive Botany, adapted to the present condition of the science. The favor with which the former editions have been re- ceived, while it has satisfied the author that the plan of the work is well adapted to the end in view, has made him the more desirous to improve its execution, and to render it a better exponent of the present state of Botany. In this view, the structural and physiological part of the work, and the chapters on the Principles of Classification and of the Natural System, have been again almost entirely rewritten, and such changes made as the advanced state of our knowl- edge required, or the author's continued experience in teaching has suggested. This has been done without in- creasing the extent of this part of the volume, which, con- sidering the limited time devoted to the study in our col- leges, &c, is found to be as full as is desirable for a text- book. Being intended as a manual for instruction merely, the Illustrations of the Natural Orders, which form the prin- cipal portion of the systematic part of the work, are brief IV PREFACE. and general. Such a sketch, however amplified, could never take the place of a Flora, or System of Plants, hut is de- signed merely to give a general idea of the distribution of the vegetable kingdom into families, &c, with a cursory no- tice of their structure, properties, and principal useful pro- ducts. In applying the principles of classification, and his knowledge of the structure of plants, to the investigation of the plants that grow spontaneously around him, the student will necessarily use some local Flora, such, for example, as the author's Manual of the Botany of the Northern United States. For particular illustrations the botanist may ad- vantageously consult the author's Genera of the Plants of the United States illustrated by Figures and Analyses from Nature, of which two volumes have been published. About twenty-four of the wood-cuts are, by permission, selected from original sketches made for a Report on the Trees of the United States, in preparation by the author for the Smithsonian Institution. The numerous figures added to this edition are wholly of an original character. The numerals enclosed in parentheses, which abound in the pages of this work, are references to other and mostly earlier paragraphs, in which the subjects or the terms in question are treated of or explained. A full Glossary or Dictionary of Botanical Terms (com- bined with an Index) is added to the volume. In this, it is thought, the student will find explanations of all the technical botanical terms he is likely to meet with in descrip- tive works, written in the English language. The words are here accentuated, in all cases where this seemed to be needful. Harvard University, Cambridge, Sept. 1857. CO X TENTS, Page INTRODUCTION. — General View of the Science . .13 PART I. STRUCTURAL AND PHYSIOLOGICAL BOTANY. CHAPTER I. — OF THE ELEMENTARY STRUCTURE OF PLANTS 17 Sect. I. Of Organization in General . . . .17 The Elementary Constitution of Plants . . . . 17 Their Organic Constitution . . . . • . .18 Distinctions between Minerals and Organized Beings 1 9 Individuals and Species 20 Life 21 Difference between Vegetables and Animals . . .21 Sect. n. Of the Cells and Cellular Tissue of Plants 22 Cellular Structure 23 The Cell as a Living Organism ...... 2G Its Formation and Growth . . . . . . 27 Original Cell-Formation . . . . • . .27 Cell-Multiplication 2S Free Cell-Multiplication within a Mother-Cell . . .30 Cell-Growth 30 Branching Cells . . . . . . . . .31 Cyclosis or Circulation in Cells . . • . . . 31 1* Yl CONTENTS. Transference of Fluid from Cell to Cell .... 33 Increase of Cell- Walls in Thickness 34 Markings of the Walls of Cells 36 Dots or Pits 37 Disks of Coniferous Wood . . . . . . .38 Bands, Kings, or Spiral Markings ..... 39 Gelatinous Coils 40 Sect. III. Of the Kinds or Transformations of Cellu- lar Tissue, viz. Woody Tissue, Ducts, etc. 40 Parenchyma ......... 41 Prosenchyma, Woody Tissue 41 Bast Tissue ......... 44 Vascular Tissue or Vessels, Dotted Ducts, &l\ . . .45 Interlaced Fibrilliform Tissue 48 Laticiferous Tissue . . . . . . . .49 Intercellular System ....... 50 Epidermal System . . . . . . . .51 Sect. IV. Of the Contents of Cells ... 52 Sap, Sugar 53 Starch 54 Amyloid .......... 55 Oils, Wax, Vegetable Acids 56 Essential Oils, Tannin, Alkaloids . . . . . .57 Chlorophyll . 58 Earthy Incrustations . . . . . . . .58 Crystals or Raphides, Cystolithes 59 CHAPTER II. — OF THE GENERAL DEVELOPMENT AND MORPHOLOGY OF PLANTS 60 Sect. I. Plants of the Lower Grade; their Develop- ment from the Cell . . . . . 61 Plants of a Single Cell 61 Plants of a Single Row of Cells 65 Plants of a Single Plane or Layer of Cells . . . .66 Plants of a Solid Tissue of Cells . . . . . 67 Plants with a Distinct Axis and Foliage . . . .67 Cellular and Vascular Plants ...... 68 Flowerless or Cryptogamous Plants . . . . .69 CONTENTS. Vll Sect. II. Plants of the Higher Grade; their Develop- ment from the Seed ..... 69 Flowering or Phamogamous Plants . . . . .60 Organs of Vegetation and of Reproduction ... 70 The Seed 70 The Development of the Embryo in Germination . . 71 Number of Cotyledons ....... 78 CHAPTER III. — OF THE ROOT, OR DESCENDING AXIS 71) Absorption by Roots ; their Growth ..... 80 Primary and Secondary Roots ...... 83 Annuals, Biennials ........ 83 Perennials ......... 84 Aerial Roots ......... 85 Epiphytes, or Air-Plants . . . . . . .87 Parasites 88 CHAPTER IV. — OF THE STEM, OR ASCENDING AXIS 91 Sect. I. Its General Characteristics and Mode of Growth . . . . . . 91 Nodes and Intern odes . . 92 Buds 93 Plan of Vegetation . 95 Phytons 96 Sect. II. Ramification 97 Branches 97 Adventitious and Accessory Buds ..... 98 Excurrent and Deliquescent Stems . . . . . 99 Definite and Indefinite Growth . . . . . .100 Propagation from Buds . . . . . . . 100 Sect. HI. The Kinds of Stem and Branches . . 101 Herbs, Shrubs, Trees, &c. 101 Stolons, Suckers, Runners . . . . . . .102 Offsets, Tendrils 103 Spines or Thorns . . . . . . . .104 Subterranean Modifications 105 Vlll CONTENTS. Rhizoma or Rootstock 106 Tuber 107 Corm 108 Bulbs and Bulblets 109 Consolidated Forms of Vegetation 110 Sect. IV. The Internal Structure of the Stem . Ill Sect. V. The Endogenous or Monocotyledonous Stem 114 Sect. VI. The Exogenous or Dicotyledonous Stem 116 The First Year's Growth 118 The Wood 119 The Bark 120 The Cambium-Layer 122 Annual Increase of the Wood 123 Sap-wood and Heart-wood 124 The Bark ; its particular Structure . . . . .126 The Living Parts of a Tree, &c 129 The Plant a Composite Being, Individuality . . .131 Comparison of Endogenous with Exogenous Structure . 132 CHAPTER V. — OF THE LEAVES 133 Sect. I. Their Arrangement 133 Phyllotaxis 133 Vernation or Praefoliation 143 Sect. H. Their Structure and Conformation . . 145 Anatomy of the Leaf 145 Stomata 150 Development of Leaves 153 The Venation and Forms of Leaves 154 Compound Leaves 163 Leaves of Peculiar Conformation or Transformation . .165 The Petiole or Leafstalk, Phyllodia, Stipules . . . 1 70 Sect. IH. The Duration of Leaves; their Action, etc. 172 Fall of the Leaf 173 Death of the Leaf 1 74 Exhalation from the Leaves, Rise of the Sap . . . 175 CONTENTS. IX CHAPTER VI — OF THE FOOD AND NUTRITION OF PLANTS 177 Sect. I. The General Physiology of Vegetation . 177 Sect. II. The Food and the Elementary Composition of Plants 179 The Organic Constituents . . . . . . 180 The Inorganic or Earthy Constituents .... 186 Sect. IH. Assimilation, or Vegetable Digestion, and its Results 190 Process and Results of Assimilation . . . . .191 Effect on the Atmosphere 199 Relations of the Vegetable to the Animal and Mineral King- doms 201 CHAPTER VII. — OF FLOWERING 204 Flowering an Exhaustive Process 204 Evolution of Heat ....... 206 Plants need a Season of Rest ...... 207 CHAPTER VHL— OF THE INFLORESCENCE . . 209 Indefinite or Indeterminate Inflorescence . . . .210 Definite or Determinate Inflorescence . . . . 217 CHAPTER IX. — OF THE FLOWER 221 Sect. I. Its Organs, or Component Parts ... 221 Sect. II. Its Theoretical Structure or Morphology 224 Sect. in. Its Symmetry 232 Alternation of the Floral Organs 235 Position as Respects the Axis and Bract . . . . 237 Sect. IV. The Various Modifications of the Flower 238 Augmentation of the Floral Circles 242 Chorisis or Deduplication 243 X CONTENTS. Anteposition or Superposition ...... 248 Coalescence of Parts ........ 249 Adnation or Consolidation ...... 250 Irregularity ......... 253 Suppression or Abortion ...... 255 Unusual States of the Receptacle ..... 266 The Disk 267 Sect. V. The Floral Envelopes in Particular . . 268 Their Development or Organogeny .... 268 Their Estivation or Prajfloration 269 The Calyx 274 The Corolla 275 Sect. VI. The Stamens 279 The Filament and Anther . . . . . . .281 The Pollen 285 Sect. VII. The Pistils 287 The Simple Pistil 288 The Placenta 289 The Compound Pistil 290 Modes of Placentation 292 Gynsecium of Gymnospermous Plants .... 296 Sect. VTTI. TnE Ovule 297 Sect. IX. Fertilization and Formation of the Embryo 300 Parthenogenesis 300 Access of the Pollen ........ 301 Action of the Pollen on the Stigma 302 Origin of the Embryo 304 CHAPTER X. — OF THE FRUIT 308 Sect. I. Its Structure, Transformations, &c. . . 308 The Pericarp or Seed-vessel . . . . . . 308 Obliteration or Alteration 309 Ripening, Dehiscence 310 Sect. II. Its Kinds 311 CONTENTS. XI CHAPTER XI. — OF THE SEED 320 Sect. I. Its Structure and Parts 320 The Nucleus and Albumen . . . . . . 322 The Embryo . . . . . . . . .323 Sect. II. Germination 328 CHAPTER XII. — OF REPRODUCTION IN CRYPTO- GAMOUS OR FLOWERLESS PLANTS . . 330 CHAPTER XIII. — OF THE SPONTANEOUS MOVEMENTS AND VITALITY OF PLANTS .... 340 Special Directions 341 Sensible Movements from Irritation .... 345 Spontaneous or Automatic Movements . . . .347 Free Movements of the Spores of Algse .... 348 Locomotion of Adult Microscopic Plants .... 349 PART II. SYSTEMATIC BOTANY. CHAPTER I — OF THE PRINCIPLES OF CLASSIFICA- TION. . . ; 352 Individuals .......... 352 Species 354 Varieties, Races, Hybrids or Cross-breeds .... 355 Genera 353 Orders or Families, Classes, &c 359 Characters ••....... 362 Binomial Nomenclature 363 Natural and Artificial Systems 365 CHAPTER II. — OF THE NATURAL SYSTEM OF BOT- ANY 366 Sketch of the Classes, &c 369 Nomenclature of Orders, Tribes, &c 373 Xli CONTENTS. CHAPTER III. — ILLUSTRATIONS OF THE NATURAL ORDERS OR FAMILIES 373 CHAPTER IV. — OF THE ARTIFICIAL SYSTEM OF LINNJEUS 511 APPENDIX. Signs and Abbreviations 517 Directions for Collecting and Preserving Plants, &c. 518 GLOSSARY OF BOTANICAL TERMS AND INDEX . 521 THE BOTANICAL TEXT-BOOK INTRODUCTION. GENERAL VIEW OF THE SCIENCE. 1. Botany is the Natural History of the Vegetable Kingdom. The vegetable kingdom consists of those beings (called Plants) which derive their sustenance from the mineral kingdom, that is, from the earth and air, and create the food upon which animals live. The proof of this proposition will be hereafter afforded, in the chapter upon the Food and Nutrition of Plants. The vegetable kingdom, therefore, occupies a position between the mineral and the animal kingdoms. Comprehensively considered, Botany accord- ingly embraces every scientific inquiry that can be made respect- ing plants, — their nature, their kinds, the laws which govern them, and the part they play in the general economy of the world, — their relations both to the lifeless mineral kingdom below them, from which they draw their sustenance, and to the animal kingdom above them, endowed with higher vitality, to which in turn they render what they have thus derived. 2. There are three aspects under which the vegetable world may be contemplated, and from which the various departments of the science naturally arise. Plants may be considered either as indi- vidual beings ; or in their relations to each other, as collectively constituting a systematic unity, that is, a vegetable kingdom ; or in their relations to other parts of the creation, — to the earth, to animals, to man. 3. Under the first aspect, namely, when our attention is directed to the plant as an individual, Ave study its nature and structure, the 2 14 INTRODUCTION. kind of life with which it is endowed, the organization through which its life is manifested ; — in other words, how the plant lives and grows, and fulfils its destined offices. This is the province of PHYSIOLOGICAL BOTANY. This department of the science naturally divides into two branches, namely, Structural Botany and Vegetable Physiology, which arise from the different views we may take of plants. The study of their organization belongs to Struc- tural Botany, which includes every inquiry respecting their structure and parts. And this may again be divided into two branches, viz.: — 1st, Vegetable Anatomy, or Phytotomy, the study of the minute structure of vegetables as revealed by the microscope ; and 2d, Organography, the study of the organs or conspicuous parts of plants, as to their external conformation ; in- cluding Morphology (the study of forms), which relates to the conformation and the symmetrical arrangement of these organs, and the modifications they undergo, either in different species, according to the conditions of their existence, or in the same indi- vidual in the course of its development, — a department analogous to what is termed Comparative Anatomy in the animal kingdom. Thus in Structural Botany, whether Ave regard the external con- formation or the minute internal structure, the plant is viewed as a piece of machinery, adapted to the accomplishment of certain ends. On the other hand, the study of this apparatus in action, endowed with life, and fulfilling the purposes for which it was in- tended, and also of the forces which operate in it and by it, is the province of Vegetable Physiology. 4. The subjects which Physiological Botany embraces, namely, Vegetable Anatomy, Organography, and Physiology, therefore, spring naturally from the study of vegetables as individuals, — from the contemplation of an isolated plant throughout the course of its existence, from germination to the flowering state, and the production of a seed like that from which the parent stock origi- nated. These branches would equally exist, and would form a highly interesting study (analogous to human anatomy and physi- ology), even if the vegetable kingdom were restricted to a single species. 5. But the science assumes an immeasurably broader interest and more diversified attractions, when we look upon the vegetable crea- tion as consisting, not of wearisome repetitions of one particular form, in itself however perfect or beautiful, but as composed of thousands INTRODUCTION. 15 of species, all constructed upon one general plan, indeed, but this plan modified in each according to the rank it holds, and the cir- cumstances in which it is placed. This leads to the second great department of the science, namely, SYSTEMATIC BOTANY, or the study of plants in their relations to one another ; as forming a vegetable kingdom, which embraces an immense number of species, resembling each other in very various degrees, and therefore capable of being grouped into hinds or genera, into orders, classes, &c. 6. Thus arises Classification, or the arrangement of plants in systematic order, so as to show their relationships ; also Special Descriptive Botany, embracing a scientific account of all known plants, designated by proper names, and distinguished by clear and exact descriptions. Necessarily connected with these departments is Terminology or Glossology, which relates to the application of distinctive names or terms to the several organs of plants, and to their numberless modifications of form, &c. The accomplishment of this object renders necessary a copious vocabulary of technical terms ; for the current words of ordinary language are not suf- ficiently numerous or precise for this purpose. New terms are therefore introduced, for accurately expressing the great variety of new ideas to which the exact comparison of plants gives rise ; and thus a technical language has gradually been formed (in this as in every other science), by which the botanist is able to describe the objects of his study with a clearness and brevity not otherwise attainable. 7. These several departments include the whole natural history of the vegetable kingdom, considered independently. But, under a third point of view, plants may be contemplated in respect to their relations to other parts of the creation ; whence arises a series of interesting inquiries, which variously connect the science of Botany with Chemistry, Geology, Physical Geography, &c. Thus, the re- lations of vegetables with the mineral kingdom, considered as to their influence upon the soil and the air, — as to what vegetation draws from the soil and what it imparts to it, what it takes from and what it renders to the air Ave breathe ; and, again, the relations of the vegetable to the animal kingdom, considered as furnishing sustenance to the latter, and the mutual subservience of plants and animals in the general economy of the world, — all these inquiries belong partly to Chemistry and partly to Vegetable Physiology; while the practical deductions from them lay the foundation of 16 INTRODUCTION. scientific Agriculture, &c. The relations of plants to the earth, considered in reference to their natural distribution over its surface and the laws that regulate that distribution, especially as connected with climate, give rise to Geographical Botany, a subject which connects Botany with Physical Geography. Under the same gen- eral department naturally falls the consideration of the changes which the vegetable kingdom has undergone in times anterior to the present state of things, as studied in the fossil remains of plants, (a contribution which Botany offers to Geology,) as well as of those changes which man has effected in the natural distribution of plants, and the alterations in their properties or products which have been developed by culture. 8. Of these three great departments of the science, that of Physiological Botany, forming as it does the basis of all the rest, first demands the student's attention. PART I. STRUCTURAL AND PHYSIOLOGICAL BOTANY. 9. Tite principal subjects which belong to this department of Botany may be considered in the most simple and natural order by tracing, as it were, the biography of the vegetable through the successive stages of its existence, — the development of its essen- tial organs, root, stem, and foliage, the various forms they assume, the offices they severally perform, and their combined action in carrying on the processes of vegetable life and growth. Then the ultimate development of the plant in flowering and fructification may be contemplated, — the structure and office of the flower, of the fruit, the seed, and the embryo plant it contains, which, after remaining dormant for a time, at length in germination develops into a plant like the parent ; thus completing the cycle of vegetable life. A preliminary question, however, presents itself. To under- stand how the plant grows and forms its various parts, and to get a clear idea of what growth is, we must first ascertain what plants are made of. CHAPTER I . OF THE ELEMENTARY STRUCTURE OF PLANTS. Sect. I. Of Organization in General. 10. The Elementary Constitution of Plants. In considering the materials of which vegetables are made, it is not necessary at the outset to inquire particularly into their chemical or ultimate com- position, that which they have in common with the mineral world. 2* 18 THE ELEMENTARY STRUCTURE OF PLANTS. As they derive all the materials of their fabric from the earth and air, plants can possess no simple element which these do not supply. They may take in, to some extent, almost every element which is thus supplied. Suffice it for the present to say, that, of the about sixty simple substances now recognized by chemists, only four are essential to vegetation and are necessary constituents of the vege- table structure. These are Carbon, Hydrogen, Oxygen, and Nitro- gen. Besides these, a few earthy bodies are regularly found in plants, in small and varying proportions. The most important of them are Sulphur and Phosphorus, which are thought to take an essential part in the formation of certain vegetable products, Potas- sium and Sodium, Calcium and Magnesium, Silicon and Aluminum, Iron and Manganese, Chlorine, Iodine, and Bromine. None of these elements, however, are of universal occurrence, nor are they actual components of any vegetable tissue. 11. Tlieil' Organic Constitution. Although plants and animals have no peculiar elements, though the materials from which their bodies spring, and to which they return, are common earth and air, yet in them these elements are Avrought into something widely different from any form of lifeless mineral matter. Under the influence of the principle of life, in connection with which alone such phenomena are manifested, the three or four simple constituents effect peculiar combinations, giving rise to a feAV organizable elements, as they may be termed ; because of them the organized fabric of the vege- table .or animal is directly built up. This fabric is in a good degree similar in all living bodies ; the solid parts, or tissues, in all assuming the form of membranes, arranged so as to surround cavities, or form the walls of tubes, in which the fluids are contained. It is called crgiutizcd structure, and the bodies so composed are called organized bodies, because such fabric consists of parts co-operating with each other as instruments or organs adapted to certain ends, and through which alone the living principle, under Avhose influence the structure itself was built up, is manifested in the operations which the plant and animal carry on. There is in every organic fabric a necessary connection between its conformation and the actions it is destined to perform. This is equally true of the minute structure, or tissues, as revealed by the microscope, and of the larger organs which the tissues form in all plants and animals of the higher grades, such as a leaf, a petal, or a tendril, a hand, an eye, or a muscle. The tenn organ- ization formerly referred to the possession of organs in this larger ORGANIZATION. 19 sense, that is, of conspicuous parts, or members. It is now applied as well to the intimate structure of these parts, themselves made up of smaller organs through which the vital forces directly act. 12. Distinctions between Minerals and Organized Beings. In no sense can mineral bodies be said to have organs, or parts subor- dinate to a whole, and together making up an individual, or an organized structure in any respect like that which has just been spoken of, and is soon (as regards plants) to be particularly de- scribed. Without attempting to contrast mineral or unorganized with organized bodies in all respects, we may briefly state that the latter are distinguished from the former, — 1. By parentage: plants and animals are always produced under the influence of a living body similar to themselves, or to what they will become, in whose life the offspring for a time participates ; while in minerals there is no relation like that of parent and offspring, but they are formed directly, either by the aggregation of similar particles, or by the union of unlike elements combined by chemical affinity, independent of the influence, and utterly irrespective of the previous existence, of a similar thing. 2. By their development: plants and animals develop from a germ or rudiment, and run through a course of changes to a state of maturity ; the mineral exhibits no phases in its existence answering to the states of germ, adolescence, and maturity, — has no course to run. 3. By their mode of growth: the former increasing by processes through which foreign materials are taken in, made to permeate their interior, and deposited inter- stitially among the particles of the previously existing substance ; that is, they are nourished by food ; — while the latter are not nourished, nor can they properly be said to gi*ow at all ; if they increase in any way, it is merely by juxtaposition, and because fresh matter happens to be deposited on their external surface. 4. By the power of assimilation, or the faculty that plants and animals alone possess of converting the proper foreign materials they receive into their own peculiar substance. 5. Connected with assimilation, as a part of the function of nutrition, which can in no sense be predicated of minerals, is the state of internal ac- tivity and unceasing change in living bodies ; these constantly under- going decomposition and recomposition, particles which have served their turn being continually thrown out of the system as new ones are brought in. This is true both of plants and animals, but more fully of the latter. The mineral, on the contrary, is in a state of 20 THE ELEMENTARY STRUCTURE OF PLANTS. permanent internal repose : whatever changes it undergoes are owing to the action of some extraneous force, not to any inherent power. This holds true even in respect to the chemical combina- tions which occur in the mineral and in the organic kingdoms. In the former they are stable ; in the latter they are less so in pro- portion as they are the more under the influence of the vital prin- ciple : as if in the state of unstable equilibrium, a comparatively slight force induces retrograde changes, through which they tend to reassume the permanent mineral state. G. Consequently the duration of living beings is limited. They are developed, they reach maturity, they support themselves for a time, and then perish by death, sooner or later. Mineral bodies have no life to lose, and contain no internal principle of destruction. Once formed, they exist until destroyed by some external power ; they lie passive under the control of physical forces. As they were formed irrespec- tive of the pre-existence of a similar body, and have no self-deter- mining power while they exist, so they have no power to determine the production of like bodies in turn. The organized being may perish, indeed, from inherent causes ; but not until it has given rise to new individuals like itself, to take its place. The faculty of re- production is, therefore, an essential characteristic of organized beings. 13. Individuals. The mass of a mineral body has no necessary limits ; a piece of marble, or even a crystal of calcareous spar, may be mechanically divided into an indefinite number of parts, each one of which exhibits all the properties of the mass. But plants and animals exist as individuals; that is, as beings, com- posed of parts which together constitute an independent whole, that can be divided only by mutilation. Each owes its existence to a parent, and produces similar individuals in its turn. So each in- dividual is a link of a chain ; and to this chain the natural-historian applies the name of 14. Species. The idea of species is therefore based upon this suc- cession of individuals, each deriving its existence, with all its peculi- arities, from a similar antecedent one, and transmitting its form and other peculiarities essentially unchanged from generation to generation. By species we mean abstractly the type or original of each sort of plant, or animal, thus represented by a perennial succession of like individuals : or, concretely, the species is the sum of such individuals. ORGANIZATION. 21 15. life. All these peculiarities of organized, as contrasted with inorganic bodies, will be seen to depend upon this : that the former are living beings, or their products. The great characteristic of plants and animals is life, which these beings enjoy, but minerals do not. Of the essential nature of the vitality which so controls the matter it becomes connected with, and of the nature of the connection between the living principle and the organized structure, we are wholly ignorant. We know nothing of life except by the phenomena it manifests in organized structures. We have adverted only to some of the most universal of these phenomena, those which are common to every kind of organized being. But these are so essentially different from the manifestations of any known physical force, that we are compelled to attribute them to a special principle. We may safely infer, however, that life is not a product, or result, of the organization ; but is a force manifested in matter, which it controls and shapes into peculiar forms, — into an apparatus, in which means are manifestly adapted to ends, and by which results are attained that are in no other way attainable. As we rise in the scale of organized structure from plants through the various grades of the animal creation, the superadded vital manifestations become more and more striking and peculiar. But the fundamental char- acteristics of living beings, — those which all enjoy in common, and which necessarily give rise to all the peculiarities above enumer- ated (12), — are reducible to two, viz.: — 1. the power of self- support, or assimilation, that of nourishing themselves by taking in surrounding mineral matter and converting it into their own proper substance ; by which individuals increase in bulk, or grow, and maintain their life : 2. the power of self-division or reproduc- tion, by which they increase in numbers and perpetuate the species.* 16. Difference between Vegetables and Animals. The distinction be- tween vegetables and minerals is therefore well defined. But the fine of demarcation between plants and animals is by no means so readily drawn. Ordinarily, there can be no difficulty in dis- tinguishing a vegetable from an animal. All the questionable * A single striking illustration may set both points in a strong light. The larva of the flesh-fly possesses such power of assimilation, that it will increase its own weight two hundred times in twenty-four hours ; and such consequent power of reproduction, that Linna3us perhaps did not exaggerate, when he affirmed that " three flesh-flies would devour the carcass of a horse as quickly as would a lion." 22 THE ELEMENTARY STRUCTURE OF PLANTS. cases occur on the lower confines of the two kingdoms, which exhibit forms of the greatest possible simplicity of structure, and of a minuteness of size that baffles observation. Even here the uncertainty may be attributable rather to the imperfection of our knowledge, than to any confusion of the essential character- istics of the two kinds of beings. If we cannot absolutely define them, or, at least, cannot always apply the definition to the actual and certain discrimination of the lowest plants from the lowest animals, Ave may indicate the special functions and characters of each. The essential characteristics of vegetables doubtless depend upon the position which the vegetable kingdom occupies between the mineral and the animal, and upon the general office it fulfils. Plants, as stated at the outset (1), are those organized beings that five directly upon the mineral kingdom, — upon the surrounding earth and air. They alone convert inorganic, or mineral, into organic matter ; while animals originate none, but draw their whole sustenance from the organized matter which plants have thus elab- orated. Plants, having thus the most intimate relations with the mineral world, ai'e generally fixed to the earth, or other substance upon which they grow, and the mineral matter on which they feed is taken directly into their system by absorption from without, and is assimilated under the influence of light in organs exposed to the air ; while animals, endowed with volition and capable of respond- ing promptly to external impressions, have the power of selecting the food ready prepared for their nourishment, which is received into an internal reservoir or stomach. The permanent fabric of plants is composed of only three elements, Carbon, Hydrogen, and Oxygen. The tissue of animals contains an additional element, viz. Nitrogen. Plants, as a necessary result of assimilating their inorganic food, decompose carbonic acid and restore its oxygen to the atmosphere. Animals in respiration continually recompose car- bonic acid, at the expense of the oxygen of the atmosphere and the carbon of plants. These peculiarities will be explained and illus- trated in the progress of this work. Sect. II. Of the Cells and Cellular Tissue of Plants. 17. The question recurs, What is the organized fabric or tissue of plants, and how is vegetable growth effected ? The stem, leaves, CELLULAR TISSUE. 23 and fruit appear to ordinary inspection to be formed of smaller parts, which are themselves capable of division into still smaller portions. Of what are these composed ? 18. Cellular Structure. To obtain an answer to this question, we examine, by the aid of a microscope, thin slices or sections of any of these parts, such, for example, as the young rootlet of a seed- ling plant. A magnified view of such a rootlet, as in Fig. 1, pre- sents on the cross-section the appearance of a network, the meshes of which divide the whole space into more or less regular cavi- ties. A part of the transverse slice more highly magnified (Fig. 2) shows the structure with greater distinctness. A perpendicular slice (Fig. 3) exhibits somewhat similar meshes, showing that the cavities do not run lengthwise through the whole root without in- terruption. In Avhatever direction the sections are made, the cav- ities are seen to be equally circumscribed, although the outlines may vary in shape. Hence, we arrive at the conclusion, that the fabric, or tissue, consists of a multitude of separate cavities, with I 2 4 closed partitions ; forming a structure not unlike a honeycomb. This is also shown by the fact, that the liquid contained in a juicy fruit, such as a grape or currant, does not escape when it is cut in two. The cavities being called Cells, the tissue thus constructed is termed Cellular Tissue. When the body is sufficiently trans- lucent to be examined under the microscope by transmitted light, this structure may usually be discerned without making a section. FIG. 1. Portion of a young root, magnified. 2. A transverse slice of the same, more mag- nified 3. A smaller vertical slice, magnified. FIG. 4. Cellular tissue from the apple, as seen in a section. 5. Some of the detached cells from the ripe fruit, magnified. FIG. 6. Portion of a hair from the filament of the Spider Lily (Tradescantia), magnified : a, vestige of the nucleus. 24 THE ELEMENTARY STRUCTURE OF PLANTS. aDnaoDDcr We may often look directly upon a delicate rootlet (as in Fig. 1), or the petal of a flower, or a piece of thin and transparent sea-weed, and observe the closed cavities, entirely circumscribed by nearly transparent membranous walls. 19. Does this cellular tissue consist of an originally homogeneous mass, filled in some way with innumerable cavities ? Or is it com- posed of an aggregation of little blad- ders, or sacs, which by their accumu- lation and mutual cohesion make up the root or other organ? Several cir- cumstances prove that the latter is the correct view. 1. The partition between two adjacent cells is often seen to be double ; showing that each cavity is bounded by its own special walls. 2. There are vacant spaces often to be seen between contiguous cells, where the walls do not entirely fit together. These intercellular spaces are sometimes so large and numerous, that many of the cells touch each other at a few points only; as in the green pulp of leaves (Fig. 7). 3. When a portion of any young and tender vegetable tissue, such as an Asparagus shoot, is boiled, the elementary cells separate, or may readily be separated by the aid of fine needles, and examined by the microscope. 4. In pulpy fruits, as in the apple, the walls of the cells, which at first cohere together, spontaneously separate as the fruit ripens (Fig. 4, 5). 20. The vegetable, then, is constructed of these cells or vesicles, much as a wall is built up of bricks. When the cells are separate, or do not impress each other, they are generally round- ed or spherical. By mutual pressure they become Y\\ many-sided. In a mass of spheres each one is touched by twelve others; so if equally impressed in every direction, the yielding cells, flattening each other at the points of contact, become twelve-sided ; and in a section, whether transverse (as in Fig. 2) or longitudinal (as in FIG. 7. A magnified section through the thickness of a leaf of Illicium Floridanum, show- ing the irregular spaces or passages between the cells, which are small in the upper layer of the green pulp, the cells of which (placed vertically) are well compacted, so as to leave only minute vacuities at their rounded ends ; but the spaces are large and copious in the rest of the leaf, where the cells are very loosely arranged, o, The epidermis or skin of the upper, b, of the lower surface of the leaf, composed of perfectly combined and thick-walled cells. FIG. 8. View of a twelve-sided cell, detached entire, from tissue like that of Fig. 9. CELLULAR TISSUE. 25 Fig. 3), the meshes consequently appear six-sided. If the organ is growing in one direction more than another, the cells commonly lengthen more or less in that direction. It is not necessary to _-^ ■ detach a cell in order to ascertain ^S its shape ; that may usually be inferred from the outlines of the |J| i t • 1 1 1 t! section m two or three directions. 21. The shape of cells, there- fore, when they compose a tissue, depends A r ery much upon the way in which they are arranged and press upon each other. "When separate, as they are in the sim- '7i plest vegetables, or when nearly free from each other, like the hairs on the surface of many plants, they determine their own form by their mode of growth, and assume a great variety of shapes, some of which are shown in the follow- ing illustrations. The natural and primitive form may be said to be roundish or spherical. By increased growth in one direction they become oblong or cylindrical, or, when still more extended, they become tubes. Of this kind are the hair-like prolongations on the surface of young rootlets (shown just beginning in Fig. 1, and more elongated in Fig. 135 — 137); and the fibres of cotton are slender hairs, consisting of single, very long cells, growing on the surface of the seed. 22. The Avails of young cells are transparent and colorless. The various colors which the parts of the plant present, the green of the foliage, and the vivid hues of the corolla, do not belong to the tissues themselves, but to the matters of different colors which the cells contain (92). As they become older, the walls often lose most of their transparency, and even acquire peculiar colors, as in the heart-wood of various trees. 23. The cells vary greatly in size, not only in different plants, but in different parts of the same plant. The largest are found in aquatics, and in such plants as the Gourd, where some of them are as much as one thirtieth of an inch in diameter. Their ordinary diameter in vegetable tissue is between %£ v and T v ! ijiy °f an mcn - PIG. 9. A small portion of the tissue of pith, seen both in transverse and longitudinal section, much magnified. 3 26 THE ELEMENTARY STRUCTURE OF PLANTS. The smaller of these sizes would allow of as many as 1728 millions of cells in the compass of a cubic inch ! 24. Some idea may be formed respecting the rate of their pro- duction, by comparing their average size in a given case with the known amount of growth. Upon a fine day in the spring, many stems shoot up at the rate of three or four inches in twenty-four hours. "When the Agave or Century-plant blooms in our conser- vatories, its flower-stalk often grows at the rate of a foot a day ; it is even said to grow with twice that rapidity in the sultry climate to which it is indigenous. In such cases, new cells must be formed at the rate of several millions a day. The rapid growth of Mushrooms has become proverbial. A gigantic species of Puff-ball has been known to attain the size of a large gourd during a single night : in this case the cells of which it is composed are computed to have been developed at the rate of three or four hundred millions per hour. But this rapid increase in size is owing, in great part, to the expansion of cells already formed. 25. The Cell as a living Organism. Thus far we have considered only the membrane or permanent wall of the cell, — that which makes up the tissue or fabric of plants, and which remains un- altered, and performs some of its offices even long after life has departed. But we should now regard the cell as a living thing, and consider what the Avail encloses, and what operations are effected in it. For the Avhole life of the plant is that of the cells which compose it ; in them and by them its products are elaborated, and all its vital processes carried on. 26. A 3 r oung, living, vitally active cell consists, — 1st, of the membrane or permanent wall, already described ; 2d, of a delicate mucilaginous film, fining the wall, called by Mohl the primordial utricle ; 3d, most commonly the centre of the cell, and sometimes the greater part of the cavity, is occupied by the nucleus, a soft solid or gelatinous body ; and 4th, the space between the nucleus and the lining membrane is filled at first by a viscid liquid, called protoplasm, having an abundance of small granules floating in it. As the cell enlarges by the growth and expansion of its walls, the space between the latter and the nucleus becomes filled with watery sap, leaving the protoplasm merely as a viscid coating of the inside of the primordial utricle, and of the nucleus, if this remains. 27. The cell-membrane, or proper wall of the cell, is chemically composed of the three elements, carbon, hydrogen, and oxygen, FORMATION AND GROWTH OF CELLS. 27 and has the same composition (when pure) in all plants. This sub- stance — the general material of vegetable fabric — is called Cellu- lose. Its chemical composition is Carbon 12, Hydrogen 10, and Oxygen 10. It is insoluble in water, alcohol, ether, and dilute acids, and, like starch, it turns blue when acted upon by iodine, aided by sulphuric acid. The primordial utricle, or delicate lining of the cell, appears to have the same composition as protoplasm. It may be regarded as an exterior portion of the mucilaginous protoplasm, which has acquired the consistence of a very soft membrane. In addition to the three elements, carbon, hydrogen, and oxygen, pro- toplasm contains nitrogen, in considerable quantity. It is colored yellow by iodine, and is coagulated by alcohol and acids. The substance of which it principally consists is named by chemists Proteine, and is known among vegetable products under various forms, viz. as diastase, gluten, fibrine, vegetable albumen, and the like. Such being the nature and the parts of the cell, we may now consider 28. Its Formation and Growth. Under this head we may briefly explain, as far as we are able, — 1st, how cells are originated; and 2d, how they are multiplied. 29. Original Cell-Formation. Cells are originated only within other cells, or at least in matter which has been contained in and elab- orated by them. They appear to be formed in the following man- ner. A portion of the elaborated or organizable matter, which abounds in the fluid contents of living cells, condenses into a soft solid, or half-solid and more or less transparent mass, usually of a globular of oval shape, the nucleus: around this nucleus a portion of protoplasm accumulates ; a denser film of the same substance forms on the surface of the protoplasm, giving the mass a definite outline ; this is the primordial utricle : upon this a layer of cellulose is soon deposited, making the cell-membrane. The nuclei in such cases are very minute, and either few or many of them may be formed in one parent cell, and be developed in this way into new cells, which are, at least at first, of small size as compared with the parent cell (Fig. 88). A variation of this mode occurs in many of the lower Alga 1 , where a considerable portion of the contents of a cell con- denses into a rounded mass, the surface becomes coated with a layer of protoplasm or primordial utricle, and this with a membrane of cellulose, completing the cell. Thus, in Vaucheria the whole green contents at the end of certain branches condense into a 28 THE ELEMENTARY STRUCTURE OF PLANTS. globular mass (Fig. 89), which at length is coated with cell-mem- brane, and so becomes a cell of considerable size. In Zygnema (Fig. 635) the whole contents of two cells are united, and give rise in a similar way to one new cell. 30. In the higher or flower-bearing division of plants, this process of original or free cell-formation occurs only in the sac in which the embryo is formed. The first cell of the embryo originates in this way ; but all the subsequent growth is effected by a different pro- cess. In the simplest grade of plants it occurs more frequently, but only in the formation of those bodies which in them take the place and fulfil the office of seeds ; that is, which serve for repro- duction. 31. It appears, therefore, that the azotized or nitrogenous mate- rial, the proteine, plays the most important part in the formation of cells. The layer of protoplasm, with its delicate coating, the primordial utricle, precedes the proper cell-membrane, and in some unexplained way causes the latter to be deposited on its sur- face. And these soft nitrogenous parts are the seat of the whole vital activity of the cell. The wall of cellulose may be regarded as a kind of protecting coat or shell, which constitutes the per- manent fabric of the plant, but is alive only so long as the living protoplasmic lining remains. 32. In a growing young cell, the walls enlarge much faster than the nucleus, and the latter soon ceases to grow at all. It is there- fore left in the centre, or else remains adherent to the Avail on one side, where traces of it may often for a long time be detected ; or more commonly it dissolves and disappears altogether. At length, in older cells, the liquid contents and the protoplasmic lining also disappear, and only the Avails of cellulose remain as the permanent vegetable fabric. The fabric of plants, however, as has already been stated, is not built up by original cell-formation, but by 33. Cell-Multiplicatioil. A living cell, formed in whatever manner, has the power of multiplying itself by dividing into tAvo, these again into two more, and so on. By this process the single cell, which each vegetable begins Avith, gives rise to the embryo or rudimen- tary plantlet contained in a seed ; and by it the embryo in germina- tion develops into a seedling, and the seedling into the herb, shrub, or tree. Vegetable groAvth accordingly consists, — 1st, of the groAvth or expansion of each cell up to its full size, which ordinarily is veiy soon attained ; and 2d, of Avhat is called their mffrismatic multiplied- FORMATION AND GROWTH OF CELLS. 29 G3 tion, namely, the successive division of cells into two. This takes place only when they are young and active, and mostly before they are full-grown. It is effected by the formation of a partition across the cavity of the cell, dividing it into two (Fig. 10-14). In this way, a single cell gives riseduction are different in appearance and in the mode of their formation from those which serve for vegetation. These reproductive cells, or Spores, with the apparatus for their production and protection, whatever it may be, constitute the organs of reproduction in Cryptogamous plants. In Phamogamous plants the organs of reproduction are the Flower, essentially consisting of Stamens and Pistils, and the result of their co-operation is the production of Seed. 118. A Seed is a body produced by the agency of a flower, which contains, within one or more coats or coverings, a ready-formed PLANTS FROM THE SEED. 71 plantlet in a rudimentary state. Flowerless or Cryptogamous plants spring from spores or single cells, -which when they germinate multi- ply to produce a tissue or an aggregation of cells, that at length grows and forms a plantlet. But a seed contains a plantlet ready formed, or a germ, which is called an Embryo. And the history of a Flowering or Phamogamous plant naturally begins with 119. The Development of the Embryo from the Seed. The embryo varies exceedingly in size, shape, and appearance in different plants ; but it is constructed upon the same general plan in all ; and the development of almost any plantlet from the seed will serve to illus- trate the principal laws and processes of vegetable growth. To commence with the study of the seedling is the readiest way to un- derstand the whole vegetable structure and life. 120. The seeds of the Eed or the Sugar Maple furnish good illustrations, and they are readily met with in germination, i. e. just developing the embryo into a plant. Also they are large enough to allow the embryo to be extracted from the seed-coats, and inspected by the naked eye, or by the aid of a common hand-glass. (Fig. 103-105.) Here the whole contents of the seed consist of an embryo, neatly coiled up within the seed-coats. If un- IU3 '"•■ *— folded, or, which is better, if examined when just unfolding itself in germination, it is seen to consist of a tiny stem or axis (Fig. 104, 105, a), bear- ing a pair of small leaves on its summit. The axis is called the Radicle, because it was supposed to be the root ; though it is really the rudiment of the stem rather than of the root, and therefore were better named the Caulicle ; but the former name is now too well established to be superseded. The two little seed-leaves (b, b) are technically called Cotyledons : and a little bud which will pres- ently appear between them (Fig. 106, c), or may be discerned there in many embryos before germination (as in the Almond, Fig. 108, a) is named the Plumule. The embryo, accordingly, is a short axis or stem bearing upon one end some rudimentary leaves ; FIG. 103. Embryo of Sugar-Maple as coiled up in the seed. 104, 105. The same, just be- ginning to unfold and develop in germination : a, the radicle, or primary stem : b, b, the cotyledons or seed-leaves. 72 DEVELOPMENT OF FLOWERING OB PHiENOGAMOUS or, in other words, it is a primary stem crowned with a leaf-bud. When it grows, this stem elongates throughout its whole length, so as usually to raise the budding apex above the surface of the soil, into the light and air, Avhere its cotyledons expand into leaves ; and at the same time from the opposite ex- tremity is formed the root, which grows in a downward direction, so as to pen- etrate more and more into the soil. The two extremities of the embryo are dif- ferently organized, are differently affect- ed by light and air, and grow in opposite directions. The budding end invaria- bly turns towards the light, and grows upwards into the air ; the root-end turns constantly from the light, and buries it- self in the dark and moist soil. These tendencies are absolute and irreversible. If the budding end happen to he point- ing downwards and the root end up- 105 wards, both will curve quite round as they grow to .assume their appropriate positions. If obstacles inter- vene, the root will take as nearly a downward, and the stem as nearly an upward direction, as possible. These are only the first manifestations of an inherent property, which continues, with only incidental modifications, throughout the whole growth of the plant, although, like instinct in the* higher animals, it is strongest at the commencement : and it insures that each part of the plant shall be developed in the medium in which it is designed to live and act, — the root in the earth, and the stem and leaves in the air. The plantlet, therefore, possesses a kind of polarity ; it is composed of two counterpart systems, namely, a Descending Axis, or root, and an Ascending Axis, or stem. The point of union or base of the two has been termed the crown, neck, or collar. Both the root and stem branch ; but the branches are repetitions of the axis from which they spring, and obey its laws ; the branches of the root tending to descend, and those of the stem to ascend. FIG. 106. A germinating embryo of Sugar-Maple, more advanced : a, the radicle elongated into the first joint of stem, bearing the unfolded cotyledons or seed-leaves, 6, and between them the plumule (c), or rudiments of the next pair of leaves ; while from its lower extremity the root, d, is formed. PLANTS FROM THE SEED. 73 121. The root and the stem grow not only in opposite directions, but in a different mode. The little stem, pre-existing in the seed, grows throughout its whole length, (but most in its upper part,) so that a radicle of perhaps less than a line in length may become a stemlet two or three inches long. It is by this elongation that the seed-leaves are raised out of the soil, so as to expand in the light and air. Meanwhile a root begins to be formed at the other end of the radicle ; and this lengthens by continued cell-multiplication mainly at its lower extremity, the parts once formed scarcely if at all elon- gating afterwards ; but the growth takes place continuously at the tip alone. The primary stem, bearing the pair of seed-leaves, soon completes its development, and ceases to lengthen. Then, if not before, the plumule (Fig. 106, c) begins its growth and develops into a second stemlet on the summit of the first, bearing its pair of leaves. It lengthens in the manner its predeces- sor did, and carries up the second pair of leaves to some distance above the first ; then from between them springs a third joint of stem, crowned with its pair of leaves (Fig. 107) ; and so on, building up the whole herb or tree by this succession of similar growths or joints of stem. The root, on the other hand, grows on in a downward direc- tion continuously, is not composed of a series of joints, and bears no leaves or other organs. 122. The youngest seedling is there- fore provided with all the organs of vegetation that the full-grown plant possesses ; and even the embryo in the seed is already a miniature vege- table. It has a stem, from the lower end of which it strikes root in ger- mination ; it has leaves, and it has or soon forms a bud, which develops into new joints of stem bearing additional leaves, while beneath it sends its root deeper and deeper FTG. 107. A seedling Maple which has developed two additional joints of stem, each with their pair of leaves. 74 DEVELOPMENT OF FLOWERING OR PH^ENOGAMOUS into the soil. The root absorbs materials for the plant's nourish- ment from the soil; these are conveyed through the stem into the leaves, and there assimilated (12, 15), under the influence of the light of the sun and the air, into organic matters which serve directly for further growth, and form the fabric of new portions of stem, new leaves, and new roots, the vegetable thus increasing its size and its power at every step. 123. Once established, therefore, the plant can provide for itself, drawing the needful materials from the earth and the air, and assimilating or organizing them by its own peculiar power. But at the beginning, and until it has sent forth its root into the soil and spread out its first leaves in the light, it must be nourished and grow by means of organized matter supplied by the parent plant. This supply in the Maple was de- posited in the seed-leaves of the embryo, and was barely sufficient to develop the radicle into a tiny stem, to form a simple root at the lower extremity, and above to expand in the light the pair of small, green seed-leaves ; when the plantlet is left to its own resources. Very commonly a larger store of nourishment is pro- vided for the plant's earliest growth. In the almond, for instance (Fig. 108), the large cotyledons are so thickened by this nourishing matter, deposited in their tissue, that they have not the appearance of leaves. It is the same in the Plum and Cherry (Fig. Ill"), and in the Apple, only on a smaller scale (Fig. 110, 111) ; and the Beech (Fig. 112 - 114) and the Bean (Fig. 115-117) afford familiar FIG. 108. Embryo (kernel) of the Almond. 109. Same, with one cotyledon removed, to show the plumule, a. FIG. 110. Section of an Apple-seed, magnified, cutting through the thickness of the cotyledons. 111. Embryo of the same, extracted entire, the cotyledons a little separated. FIG. lll a . Germination of the Cherry, showing the thick cotyledons little altered, and the plumule developing the earliest real foliage. PLANTS FROM THE SEED. 75 illustrations of the kind. The ample store of nourishment in such cases enables the germinating plantlet to grow with remarkable vigor, and to develop the strong plumule with its leaves before the seed-leaves have expanded, or the root has obtained much foothold in the soil. In these instances the cotyledons are so much thickened that, although they turn greenish in the light, they only im- perfectly as- sume the ap- i pearance and perform the ( functions of or- dinary leaves ; and the earli- est real foliage consists of the leaves of the plumule. Such cotyledons serve chiefly as depositories of nourishment for the germi- 117 11S nating plant. 114 124. Still more strongly marked cases of this kind are presented by the Pea (Fig. 118, 119), the Chestnut and Horsechestnut, the Oak (Fig. 120, 121), &c. Here the cotyledons are excessively thickened, so as to lose all likeness to leaves and all power of ful- filling the office of foliage. Accordingly they remain unchanged within the seed-coats, supplying abundant nourishment to the FIG. 112. A Beech-nut, cut across. 113. Beginning germination of the Beech, showing the plumule growing before the cotyledons have opened or the root has scarcely formed. 114. The same, a little later, with the second joint lengthened. FIG. 115. The embryo (the whole kernel) of the Bean. 116. Same early in germination ; the thick cotyledons expanding and showing the plumule. 117. Same, more advanced in germination ; the plumule developed into a joint of stum bearing a pair of leaves. 76 DEVELOPMENT OF FLOWERING OR PH^ENOGAMOL'S plumule, which gives rise to the first leaves that appear. As the radicle itself scarcely if at all elongates, the cotyledons are not ele- vated in germination but remain under ground (i. e. are hypogceous), or rest on the surface of the soil. 125. Jn all the foregoing illustrations the nourishment provided for the growth of the embryo into a plantlet is deposited in the tissue of the embryo itself, i. e. in the seed- leaves. In other cases it is depos- ited around the embryo ; when it forms what is commonly called the Albumen of the seed. This makes up the principal bulk of/ the seed in the Buckwheat, In- dian Corn (Fig. 126, 127), and most other sorts of grain. The greater the quan- tity of this, the floury part of the seed, the smaller or less developed is the embryo, or the less thick are its cotyledons. In the Morning- Glory, for instance (Fig. 122-125), where the embryo is surround- ed by mucilaginous albumen, the cotyledons appear in the seed as a pair of very thin and well-formed green leaves. These absorb the nourishment required for the plantlet's earliest growth from FIG. 118. Embryo of a Pea. 119. The same in germination. FIG. 120. An acorn, divided lengthwise, showing a section of the very thick and fleshy cotyledons and the very small radicle. 121. Germination of the acorn. PLANTS FROM THE SEED. 77 the surrounding albumen, which in germination is gradually lique- fied, its starch or amyloid being transformed into dextrine and sugar (80, 82, 83). Thus nourished, the radicle rapidly lengthens into a stem, and develops a root from its 122 123 lower extremity, connecting it with the soil ; and when the enlarging cotyledons extricate themselves froni the decaying seed-coats and expand in the light as the first pair of leaves, the plantlet is already established as a complete miniature vege- table, able to nourish it- self, and make sufficient provision for its own con- tinued growth. m 125 126. The embryo in seeds provided with albumen is sometimes very small, as in Fig. 131, or even much more minute, and with its parts so rudimentary that they are hardly or not at all discernible previous to their gradual development in germination. But sometimes it is pretty large, and with* all its parts 129 obvious in the seed ; as in the Morning-Glory and in Indian Corn (Fig. 122). The latter has a highly organized FIG. 122. Seed and embryo of the common Morning-Glory, cut across ; the latter seen edgewise. 123. Embryo of the same, detached and straightened, seen flatwise. 124. Germi- nating Morning-Glory. 125. The same further advanced ; its two thin seed-leaves expanded. FIG. 126. A grain of Indian Corn, seen flatwise, divided through the embryo, which is viewed lying on the albumen, which makes the principal bulk of the seed. FIG. 127. Another grain of Corn, cut through the middle in the opposite direction, divid- ing the embryo through its thick cotyledon and its plumule, the latter consisting of two leaves, one enclosing the other. FIG. 128. The embryo taken out whole : the thick mass is the cotyledon ; the narrow body partly enclosed by it is the plumule ; the little projection at its base is the very short radicle enclosed in the sheathing base of the first leaf of the plumule. FIG. 129. A grain of Indian Corn in germination. 7* 78 DEVELOPMENT OF PILENOGAMOUS PLANTS. embryo, with a strong and well-developed plumule, of several leaves enwrapped one within another ; and, being amply nourished by the copious mealy albumen, it sprouts with re- markable vigor, sending up three or four leaves in rapid succession before the earliest has completed its growth, at the same time sending forth additional roots downwards into the soil. Here also, as in the Pea and the Oak, &c. (124) the germination is hypogceous, the cotyledons remaining in the seed under ground, and the leaves which appear above ground belonging to the plumule. This is also the/ case in the Iris (Fig. 132) and most plants of the same class. But in the Onion the co- tyledon (which is single) lengthens, raises the seed out of the ground, and be- comes the first leaf. 127. In Indian Corn (Fig. 130), in Iris (Fig. 132), and also in the germinating Cher- ry (Fig. IIP), Oak (Fig. 121), and Pea (Fig. 119), the leaves of the plumule succeed one another singly, that is, there is only one upon each joint of stem : in other words, the leaves are alternate. Whereas in the seedling Beech and the Bean (Fig. 114, 11,7) these early leaves are in pairs, that is, are opposite. A similar difference is to be noticed in the embryo as to the 128. Number Of Cotyledons. All the earlier illustra- tions are taken from plants which have a pair of cotyle- dons, or seed-leaves, belonging to the first joint of stem, that is, to the radicle. Such embryos are accordingly said to be Dicotyledonous, — a name expressive of this fact. But in the Lily, Onion, Iris, Indian Corn, and the like, the embryo FIG. 130. Indian Corn more advanced in germination, and with a cluster of roots. FIG. 131. Section of a seed of Iris or Flower-de-Luce, magnified, showing the small embryo enclosed in the albumen, near its base. 132. Germinating plantlet of Iris. THE ROOT. 79 has only one cotyledon or true seed-leaf (Fig. 128, &c.) ; the other leaves, if any are apparent, are enclosed by the cotyledon and be- long to the plumule ; and the embryo with one cotyledon is ac- cordingly termed Monocotyledonous. The difference in this respect coincides with striking differences in the structure of the stems, leaves, and blossoms, and lays a foundation for the division of Flowering or Phtenogamous plants (114) iuto two great Classes. 129. In a few plants, such as Pines, the embryo is provided with from three to ten cotyledons, which expand into a circle of as many green leaves in germination (Fig. 133, 134) : such an embryo is said to be Polycotyledoxous, i. e. of many cotyledons. 130. Having taken this general survey of the development of Phamogarnous plants from the seed, and of their common plan of growth, their further development and their morphology may best be studied by examining in succession the three universal organs of vegetation (116) of which they all consist, viz. the Eoot, Stem, and Leaves. CHAPTER III. OF THE ROOT, OR DESCENDING AXIS. 131. The Root is the descending axis (120), or that portion of the body of the plant which grows downwards, ordinarily fixing the vegetable to the soil and absorbing nourishment from it. As already mentioned (121), the root grows in length by continual additions of new fabric to its lower extremity, elongating from that part only or chiefly ; so that the tip of a growing root always consists of the most newly formed and active tissue. It begins, in germination, at the root-end of the radicle. That only this extremity of the radicle is root is evident from the mode in which the radicle grows, namely, FIG. 133. Section of a seed of a Pine, with its embryo of several cotyledons. 134. Early seedling Pine, with its stemlet, displaying its six seed-leaves. 80 THE ROOT, by lengthening throughout every part; which is a characteristic feature of the stem. 132. The root, however, does not grow from its very apex, as is commonly stated ; but the new formation (by continued multiplica- tion of cells, 33) takes place just behind the apex (Fig. 135), which consists of an obtusely conical mass of older cells. As these wear away or perish, they are replaced by the layer beneath ; and so the advancing point of the root consists, as inspection plainly shows, of older and denser tissue than the portion just behind it. The point of every branch of the root is capped in the same way. It follows that the so-called spongioles or spongelets of the roots, or enlarged tips of delicate forming tissue, have no ex- istence. Not only are there no special organs of this sort, but absorption evidently does not take place, to any considerable extent, through the rather firm tissue of the very point itself. 133. Absorption by Roots. As the surface of the root, like every part of a plant, consists of closed cells, it is evident that the moist- ure it so largely takes in must iss be imbibed through the walls of the cells, by endosmose (40) ; and that the whole surface of a fresh root will take part in ab- sorption. The newer the root, however, the more actively does it absorb, the cells then having thinner walls. As they become older, the superficial layer of cells thicken their walls and form a kind of skin, or epider- mis (69), through which absorp- tion does not take place so free- 13r ly. Roots accordingly absorb mostly by their fresh tips and the adjacent parts ; and these are constantly renewed by growth, and FIG. 135. The tip of the root of a seedling Maple (Fig. 106), magnified : a, the place where growth is mainly taking place, hy cell-multiplication : b, the original tip of the radicle. FIG. 136, 137. Tortious of the surface of the same, highly magnified, showing the nature of the root-hairs or fibrils. ITS STRUCTURE AND GROWTH. 81 extended farther into the soil. The absorbing surface of the new parts of roots is greatly increased by the 134. Root-hairs, or delicate fibrils which they bear. These are often discernible by the naked eye, as in the young seedling Maple (Fig. 106), and may almost always be plainly shown by a moderate magnifying power, as in Fig. 135 ; while a higher power distinctly reveals their nature, as prolongations of some of the superficial cells from a certain point into slender tubes (Fig. 136, 137), thus largely increasing the absorbing surface. As fast as the superficial cells are converted into epidermis, the root-hairs die away, fresh ones taking their place on the newer parts. 135. The advancing extremity of the root consists of parenchyma alone ; but vessels and woody tissue appear in the forming root soon after their appearance in the radicle or stemlet above. The arrangement of the woody matter is generally the same as in the stem, except that the root seldom exhibits a distinct pith. The root increases in diameter in the same manner as the stem. (Chap. IV. Sect. IV., V.) 136. The growth of the root and its branches keeps pace with the development of the stem. As the latter shoots upward and expands its leaves, from which water is copiously exhaled during vigorous vegetation, the former grow onward and continually renew the tender tissue through which the absorption, required to restore what is lost by evaporation or consumed in growth, is principally effected. Hence the danger of disturbing the active roots during the season of growth. In early summer, while new branchlets and leaves are developing, and when the sap is rapidly consumed by the fresh foliage, the rootlets are also in rapid action, are extending at a corresponding rate, and their tender absorbing points are most fre- quently renewed. They cannot now be removed from the soil with- out injury, at the very time when their action is essential to restore the liquid which is continually exhaled from the leaves. But at the close of summer, as the leaves become inactive and the growth of the season is attained, the rootlets also cease to grow, the epidermis forms a comparatively firm covering quite down to the tip, and ab- sorption at length ceases. This indicates the proper period for transplanting, namely, in the autumn after vegetation is suspended, or in early spring before it recommences. 137. This elongation of roots by their advancing points alone is admirably adapted to the conditions in which they are placed. 82 THE ROOT, Growing as they do in a medium of such unequal resistance as the soil, if roots increased like growing stems, by the elongation of their whole body, they would be thrown, whenever the elongating force was insufficient to overcome the resistance, into knotted or con- torted shapes, ill adapted for the free transmission of fluid. But, lengthening only at their farthest extremity, they insinuate them- selves with great facility into the crevices or yielding parts of the soil, and afterwards by their expansion in diameter enlarge the cavity ; or, when arrested by insuperable obstacles, their advancing points follow the surface of the opposing body until they reach a softer medium. In this manner, too, they readily extend from place to place, as the nourishment in their immediate vicinity is consumed. Hence, also, may be derived a simple explanation of the fact, that roots extend most rapidly and widely in the direction of the most favorable soil, without supposing any self-determining power beyond what belongs to all growing parts. (Chap. XIII.) 138. We have taken the root of the seedling as an example and epitome of that of the whole herb or tree ; as we rightly may, for in its whole development the root produces no other parts ; it bears nothing but naked branches, which spring from different portions of the surface of the main root, nearly as this sprung from the radicle, and exactly imitate its growth. They and their ramifications are mere repetitions of the original descending axis, serving to multiply the amount of absorbing surface. The branches of the root, more- over, shoot forth irregularly, or at least in no order like that of the branches of the stem, which have a symmetrical arrangement, de- pendent upon the arrangement of the leaves (1G6). 139. To the general statement that roots give birth to no other organs, there is this abnormal, but by no means unusual exception, that of producing buds, and therefore of sending up leafy branches. Although not naturally furnished with buds, like the stem, yet, under certain circumstances, the roots of many trees and shrubs, and of some herbs, have the power of producing them abundantly. Thus, when the trunk of a young Apple-tree or Poplar is cut off near the ground, Avhile the roots are vigorous and full of elaborated sap, those which spread just beneath the surface produce buds, and give rise to young shoots. The roots of the Madura, or Osage Orange, habitually give rise to such irregular or adventitious (1G8) buds and branches. 140. Although the root does not produce ascending axes, or stems, IN ANNUAL AND BIENNIAL PLANTS. 83 except in certain rather unusual instances, yet stems habitually pro- duce roots, whenever circumstances favor it, namely, when they are covered by the damp and moist soil, or rest on its surface. Roots accordingly may be distinguished into primary and secondary. 141. The Primary Root is that which originates from the root end of the embryo in germination, including also its branches. If this continues as a main root, it commonly forms a tap-root. But very often the main root, is soon lost in the branches. Sometimes a cluster of roots is produced directly from the lower extremity of the radicle, as in the Pumpkin, and Indian Corn (Fig. 180). In the latter the second and the succeeding short joints of stem also send out roots. These are early instances of 142. Secondary Roots, i. e. roots emitted by other parts of the ascending axis than the radicle. Most creeping plants produce them at every joint ; and most branches, when bent to the ground and covered with earth, so as to afford the moisture and darkness they require, will strike root. So, often, will separate pieces of young stems, if due care be taken ; as when plants are propagated by cuttings. Cryptogamous plants, growing from spores and hav- ing no embryo stem or axis to commence with, are furnished with secondary roots only. 143. Viewed as to the duration of the plant, roots are distin- guished into annual, biennial, and perennial. 144. Annual Roots are those of a plant which springs from the seed, flowers, and dies the same year or season. Such plants always have fibrous roots, composed of numerous slender branches, fibres, or rootlets, proceeding laterally from the main or tap-root ; or else the whole root divides at once into such fibrous branches, as in all annual Grasses (Fig. 130). These multiplied rootlets are well adapted for absorption from the soil, but for that alone. The food which the roots absorb, after being digested and elaborated in the leaves, is all expended in the production of new leafy branches, and at length of blossoms. The flowering process and the maturing of the fruit exhaust the vegetable greatly (in a manner hereafter to be explained), consuming all the nourishing material which it con- tains, or storing it up in the fruit or seed for its offspring ; and the exhausted plant perishes at the close of the season, or whenever it has fully gone to seed. 145. Biennial Roots are those of plants which do not blossom until the second season, and which die when they have matured their 84 THE ROOT. seed. Such plants send up no lengthened stem during the first summer, but produce a large tuft of leaves next the ground, and proceed to elaborate what they re- ceive from the roots and from the air into organic or nourishing matter, and store it up in the root, in the form of starch, vegetable jelly, and the like. The root enlarges, or becomes fleshy, as this accumulates. In biennials this accumulation generally takes place in the primary or main root, as in the Radish, Carrot, Beet, &c. This, when only moderately thickened and taper- ing downwards, is a common tap-root : when more enlarged and broadest at the crown, or junction with the ex- tremely abbreviated stem, it forms a conical root, like that of the common Beet and Parsnip : when broadest in the middle and tapering to both ends, it is spindle-shaped or fusi- form, as in the Radish (Fig. 138) : when much broader than long, and abruptly contracted below, like a turnip, it is napiform. Such roots, abounding in nourishment, are appropriated by man for food. The plant itself uses this store for the same purpose. When the vegetation of these biennials is resumed, the following spring, the new shoots, fed by this abundant stock of nourishment provided for them, grow with great vigor, and produce flowers, fruit, and seed almost entirely at its expense ; and this stock being exhausted by the time the seeds are matured, when the cells of the great root will be found to be emptied of their contents and dead, the plant perishes. 146. Perennial Roots are those of plants which last year after year. In shrubs and trees the roots themselves live and grow indefinitely ; but in perennial herbs the same roots seldom survive more than a year or two, and a new set is formed annually. Here, also, a store of nourishment for the vigorous commencement of the succeeding year's growth is not unfrequently deposited in the root. The Sweet Potato, the Peony, and the Dahlia (Fig. 139), furnish good illustra- tions of the kind. These roots are generally fa scicled or clustered; that is, they consist of a cluster of roots from the base of the stem. FIG. 138. Fusiform root of the Radish, with some foliage. ITS STRUCTURE AND GROWTH. 85 While some of these remain slender and serve merely for absorption, others, thickened by this deposit, may become tuberous (as in Fig. 139) ; and buds, formed on the stem just above, draw upon this store when they start into growth in the spring. These particular roots perish when exhausted of their store ; but new accumulations have meanwhile been formed in some of the roots of the season, which serve the same purpose the following spring ; and so the plant survives, year after year. 147. Some less ordinary modifica- tions of roots remain to be noticed. It has already been stated that they may spring (as secondary roots, 142) from any part of the stem, although they commonly do so only when this 139 rests on or is covered by the soil, which affords the darkness and moisture congenial to them. Some stems, however, strike root freely in the open air, forming 148. Aerial Roots. The Ivy of Europe, our own Poison Ivy (Rhus Toxicodendron), and the Trumpet Creeper climb by such roots, in the form of small rootlets, which attach themselves to the bark of trees, &c. These serve merely for mechanical support. Other plants produce larger aerial roots, which, emitted from the stem in the open air, descend to the ground and establish themselves in the soil. This may be observed, on a small scale, in the stems of In- dian Corn, where the lower joints often produce roots which grow to the length of several inches before they reach the ground. More remarkable cases of the kind abound in those tropical regions where the sultry air, saturated with moisture for a large part of the year, favors the utmost luxuriance of vegetation. The Pandanus or Screw-Pine (a Palm-like tree, often cultivated in our conserva- tories) affords a well-known instance. Here (Fig. 140) strong roots, emitted in the open air from the lower part of the trunk, and soon reaching the soil, give the tree the appearance of having been par- tially raised out of the ground. The famous Banyan-tree of India (Fig. 142) affords a still more striking illustration. In this the FIG. 139. Fascicled tuberous roots of the Dahlia. 86 THE ROOT. aerial rootlets strike from the horizontal branches of the tree, often at a great height, at first swinging free in the air, but finally reach- in"; and establishing themselves in the ground, where they increase in diame- ter and form acces- sory trunks, sur- rounding the origi- nal boll and sup- porting the wide- spread canopy of branches and foli- age. Very similar is the economy of the Mangrove (Fig. 141), which forms impenetrable thick- ets on low and mud- dy sea-shores in the tropics, and even occurs on the coast of Florida and Lou- isiana. Here aerial roots spring not only from the main trunk, as in the Pandanus, but also from the branchlets, as in the Banyan. FIG. 140. The Pandanus, or Screw-Pine; with, 141, a Mangrove-tree (Rhizophora Mangle} FIG. 142. The Banyan-tree, or Indian Fig (Ficus Indica). EPIPHYTES OR AIR-PEANTS. 87 Moreover, this tendency to shoot in the air is shown even in the embryo, which begins to germinate while the fruit is yet attached to the parent branch, often elongating its radicle to the length of a foot or more before the fruit falls to the ground. 149. Epiphytes, or Air-PlailtS, exhibit a further peculiarity. Their roots not only strike in the open air, but throughout their life have no connection with the soil. These generally grow upon the trunks and branches of trees ; their roots merely adhering to the bark to fix the plant in its position, or else hanging loose in the air, from which such plants draw all their nourishment. Of this kind are a large portion of the gorgeous Orchidaceous plants of very warm and humid climes, which are so much prized in hot-houses, and which, in their flowers as well as their general aspect, exhibit such fantastic and infinitely varied forms. Some of the flowers resemble butter- flies, or strange insects, in shape as well as in gaudy coloring ; such, for example, as the Oncidium Papilio (Fig. 143). To another FIG. 143. Oncidium Papilio, and, 144, Comparettia rosea; two epiphytes of the Orchis family ; showing the mode in which these Air-plants grow. 88 THE ROOT. family of Epiphytic plants belongs the Tillandsia, or Long Moss, which, pendent in long and gray tangled clusters or festoons from the branches of the Live-Oak or Long-leaved Pine, gives such a peculiar and sombre aspect to the forests of the warmer portions of our Southern States. They are called Air-plants, in allusion to the source of their nourishment ; and Epiphytes, from their grow- ing upon other plants, and in contradistinction to 150. Parasites, that not only grow upon other vegetables, but live at their expense ; which Epiphytes do not. Parasitic plants may be divided into two sorts, viz. : — 1st, those that have green foliage ; and 2d, those that are destitute of green foliage. They may vary also in the degree of parasitism ; some being absolutely dependent upon the foster plant for nourishment, while others, such as the Cursed Fig (Clusia rosea) of Tropical America, often take root in the soil, and thence derive a part of their support. The latter oc- curs only in 151. Green Parasites, or those furnished with green foliage, or proper digestive organs of their own. These strike their roots through the bark and directly into the new wood of the foster plant; whence they draw the ascending, mostly crude sap, which they have to assimilate in their own green leaves. The Mistletoe is the most familiar example of this class. It is always com- pletely parasitic, being at no period connected with the earth ; but the seed germinates upon the trunk or branch of the FIG. 145. Roots of Gerardia flava ; some of the rootlets attaching themselves parasitically to the root of a Blueberry. (From a drawing by Mr. J. Stauffer ) FIG. 146. Section of one of the attached rootlets, showing the union. PARASITIC PLANTS. 89 tree where it happens to fall, and its nascent root, or rather the woody mass that it produces in place of the root, penetrates the bark of the foster stem, and forms as close a junction with its } r oung wood as that of a natural branch. The Cursed Fig, commonly be- ginning as a parasite, sends down aerial roots, some of which strike into the wood of the foster tree lower down, while others descend to the ground and draw from it a portion of their sustenance in the ordinary manner. Some common herbaceous plants, hitherto not suspected of such habits, have recently been found to fix themselves clandestinely, under ground, by means of some of their rootlets, to the roots of neighboring plants, and furtively draw from them a portion of their sustenance. This is the case with our Comandra, as well as with the Thesiums of the Old World, and also with our Gerardias and many other plants of that family, which have long been known as uncultivable, although the cause of their being so has only lately been detected. It would appear that this partial parasitism is necessary to their existence. Gerardia appears to im- plant its rootlets upon the bark of the roots of neighboring shrubs, and therefore to steal elaborated sap (Fig. 145, 146). 152. Pale or Colored Parasites, such as Beech-Drops, Pine-Sap, &c, are those which are destitute of green herbage, and are usually of a white, tawny, or reddish hue ; in fact, of any color except green. These strike their roots, or sucker-shaped discs, into the bark, mostly that of the root, of other plants, and thence draw their food from the sap already elaborated. They have accordingly no occasion for digestive organs of their own, i. e. for green foliage. The Dodder (Fig. 147) is a common plant of this kind which is parasitic above ground. Its seeds germinate in the earth ; but when the slender twining stem reaches the surrounding FIG. 147. The common Dodder of the Northern States (Cuscuta Grono-rii), of the natural size, parasitic upon the stem of an herb : the uncoiled portion at the lower end shows the mode of its attachment. 148. The coiled embryo taken from the seed, moderately magnified. 149. The same in germination ; the lower end elongating into a root, the upper into a thread- like leafless stem. 8* 90 THE ROOT. herbage, it forms suckers, which attach themselves firmly to the surface of the supporting plant, penetrate its epidermis, and feed upon its juices ; while the original root and base of the stem perish, and the plant has no longer any connection with the soil. Thus stealing its nourishment ready prepared, it requires no proper diges- tive organs of its own, and, consequently, does not produce leaves. This economy is foreshadowed in the embryo of the Dodder, which is a naked thread spirally coiled in the seed (Fig. 148, 149), and presenting no vestige of cotyledons or seed-leaves. A species of Dod- der infests and greatly injures flax in Europe, and sometimes makes its appearance in our own flax-fields, having been introduced with the imported seed. Such parasites do not live upon all plants in- discriminately, but only upon those whose elaborate juices furnish a propitious nourishment. Some of them are restricted, or nearly so, to a particular species ; others show little preference, or are found indifferently upon several species of different families. Their seeds, in some cases, it is said, will germinate only when in contact with the stem or root of the species upon which they are destined to live. Having no need of herbage, such plants may be reduced to a stalk bearing a single flower (Fig. 965) or a cluster of flowers (Fig. 9G8), or even to a single blossom developed from a bud directly parasitic on the bark of the foster plant. Of this kind are the several species of Pilostyles (parasitic flowers on the shoots of Leguminous plants) in Tropical America, one species of which was recently discovered by Mr. Thurber near the southern borders of New Mexico. Here the flowers are small, only about a quarter of an inch in diameter. The most wonderful plant of this kind is that vegetable Titan, the Eafflesia Arnoldi of Sumatra (Fig. 150), which grows upon the stem of a kind of Grape-vine. It is a parasitic flower, measuring FIG. 150. Rafflesia Arnoldi ; an expanded flower, and a bud, directly parasitic on the stem of a vine : reduced to the scale of half an inch to a foot. THE STEM. 91 nine feet in circumference, and weighing fifteen pounds ! Its color is light orange, mottled with yellowish-white. 153. Among Cryptogamous plants, numerous Fungi are parasitic upon living, especially upon languishing vegetables ; others infest living animals ; the rest feed on dead or decaying vegetable or animal matters : all are destitute of chlorophyll or anything like green herbage. It is probable that our Monotropa, or Indian Pipe, a pallid Phamogamous plant, looking like a Fungus, actually lives like one, and draws its nourishment, at least in great part, from the decaying leaves among which it grows. CHAPTER IV. OF THE STEM, OR ASCENDING AXIS. Sect. I. Its General Characteristics and Mode op Growth. 154. The Stem is the ascending axis, or that portion of the trunk which in the embryo grows in an opposite direction from the root, seeking the light, and exposing itself as much as possible to the air. All Phamogamous plants (114) possess stems. In those which are said to be acaulescent, or stemless, it is either very short, or concealed beneath the ground. Although the stem always takes an ascending direction at the commencement of its growth, it does not uniformly retain it ; but sometimes trails along the surface of the ground, or burrows beneath it, sending up branches, flower-stalks, or leaves into the air. The common idea, that all the subterranean portion of a plant belongs to the root, is by no means correct. 155. The root gives birth to no other organs, but itself directly performs those functions which pertain to the relations of the vege- table with the soil ; — its branches bind the plant to the earth ; its newly formed extremities or rootlets imbibe nourishment from it. But the aerial functions of vegetation are chiefly carried on, not so much by the stem itself as by a distinct set of organs which it bears, namely, the leaves. Hence, the production of leaves is one of the 92 THE STEM, characteristics of the stem. These are produced only at certain definite and symmetrically arranged points, called 156. Nodes, literally knots, so named because the tissues are here more or less condensed, interlaced, or interrupted, as is conspicuous- ly seen in the Bamboo, in a stalk of Indian Com, or of any other Grass. Here each node forms a complete ring, because the leaf arises from the whole circumference of the stem at that place. When the base of the leaf or leafstalk occupies only a part of the circumference, the nodes are not so distinctly marked, except by the leaves they bear, or by the scars left by their fall (Fig. 151, &c.) They are often called joints, and sometimes, indeed, the stem is actually jointed, or articulated, at these points ; but commonly there is no tendency to separate there. Each node bears either a single leaf (as in Fig. Ill, 121, &c), or two leaves placed on opposite sides of the stem (as in Fig. 107), or else tlu-ee or more, placed in a ring (in botanical language, a whorl or verticil) around the stem. The naked portions or spaces that intervene between the nodes are termed 157. Illteriiodes. The undeveloped stem is, in fact, made up of a certain number of these leaf-bearing points, separated by short in- tervals ; and its growth consists, primarily, in the successive elonga- tion of these internodes so as to separate the nodes more or less, and allow the leaves to expand. 158. This brings to view the leading peculiarity of the stem ; namely, that it is formed of a succession of similar parts, developed one upon the summit of another, each with its own independent growth. Each developing internode, moreover, lengthens through- out its whole body, unlike the root, which elongates continuously from its extremity alone (121). To have a good idea of this, we have only to observe the gradual evolution of a germinating plant, where each internode develops nearly to its full length, and ex- pands the leaf or pair of leaves it bears, before the elongation of the succeeding one commences. As already described (120, &c), the radicle, or internode which pre-exists in the embryo, elongates, and raises the seed-leaves into the air ; they expand and elaborate the material for the next joint, the leaves of which in turn prepare the material for the third, and so on. The internode lengthens principally by the elongation of its already formed cells, particularly in its lower part, which continues to grow after the upper portion has finished. ITS STRUCTURE AND GROWTH. 93 159. Buds. The apex of the stem, accordingly, is always crowned with an undeveloped portion, with rudimentary parts similar to those already unfolded, that is, with a Bud. The embryo itself may be viewed as an internode (the radicle) bearing the fundamental bud (the plumule) on its apex, from which the whole plant is de- velopod, just as an ordinary bud of a tree or shrub develops to form the growth of the season. Except that, in the latter case, the different steps follow each other more closely ; for the bud usually has a considerable number of parts ready formed in miniature before it begins to grow, and has a full store of assimilated sap accumulated in the parent stem to feed upon. This is no less the case in many strong embryos highly developed in the seed, and supplied with abundant nourishment, either in the cotyledons, as in the Pea (Fig. 119) and Oak (Fig. 120), or in the albumen, as in Indian Corn (Fig. 126-130). The strong buds which in many shrubs and trees crown the apex of a stem when it has completed its growth for the season, often exhibit the whole plan and amount of the next year's growth ; the nodes, and even the leaves they bear, being already formed, and only re- quiring the elongation of the internodes for their full ex- pansion. This is rudely shown in the annexed diagrams, Fig. 151, 152. As the bud (Fig. 153) is well supplied with nourishment in spring by the stem on which it rests, its axis elongates rapidly ; and although the growth commences with the lowest internode, yet the second, third, FIG. 151. Diagram of the vertical section of a strong bud, such as that of Ilorsechestnut. FIG. 152. The axis of the same developing, the elongation beginning with the lowest inter- node, soon followed by the others in succession. FIG. 153. A year's growth of Ilorsechestnut, crowned with a terminal bud : a, scars left by the bud-scales of the previous year : b, scars left by the fallen leafstalks : c, axillary buds. FIG. 154. Branch and buds (all axillary) of the lilac. 94 THE STEM, and fourth internodes, &c. have begun to lengthen long before the first has attained its full growth. The stem thus continued from a terminal bud is, if it survive, again terminated with a similar bud at the close of the season, which in its development repeats the same process. A set of narrow rings on the bark (Fig. 153, a) commonly mark the limit of each year's growth. These are the scars left by the fall of the scales of the bud ; and these, in the Horsechest- nut, and other trees with large scaly buds, may be traced back on the stem for a series of years, growing fainter with age, until they are at length ob- literated by the action of the weather and the distention caused by the in- crease of the stem in diameter. The same is the case with the more con- spicuous leaf-scars, or marks on the bark left by the separation of the leaf- stalk, which are for a long time con- spicuous on the shoots of the Horse- chestnut (Fig. 153, b) and the Mag- nolia (Fig. 155). 160. A bud, therefore, is nothing more than the first stage in the de- velopment of a stem, with the axis still so short that the rudimentary leaves within successively cover each other, while the whole is covered and pro- tected by the scales without. Buds vary greatly, however, in size, ap- pearance, and degree of development. Those of many shrubs and trees are minute, and hidden by the bark until their vernal growth commences, as in FIG. 155. Branch of Magnolia Umbrella, of the natural size, crowned with the terminal bud ; and below exhibiting the large, rounded leaf-scars, as well as the rings or annular scars left by the fall of the bud-scales of the previous season. 156. A detached scale from a similar bud ; its thickened axis is the base of a leafstalk ; the membranous sides consist of the pair of stipules. ITS STRUCTURE AND GROWTH. 95 Sumac, Locust, Honey-Locust (Fig. 164), &c. : in these buds the parts are few and very rudimentary, and are mostly formed as they develop. In some, they are naked, that is, are entirely destitute of protecting scales, and exhibit the forming leaves directly exposed to the air, just as they are hi herbs. This occurs in many tropical trees, but not in all, and in some shrubs of cold climates, such as our Viburnum nudum and V. lantanoides. But the greater number of plants which have a winter to endure are provided with scaly buds. Those of Beech and Hickory, as well as of Horsechest- nut and Magnolia already referred to, are conspicuous and well- developed examples. The scales serve to protect the tender parts within against injury from moisture and from sudden changes in temperature during the dormant state. To ward off moisture more effectually, they are sometimes coated with a waxy, resinous, or balsamic exudation, as is conspicuous on the scales of the Horse- chestnut, Balsam-Poplar or Balm of Gilead, and Balsam-Fir. To guard against sudden changes of temperature, they are often lined, or the rudimentary leaves within invested with non-conducting down or wool. 161. The bud-scales themselves are leaves in a modified state. This is evident from their situation and arrangement, which are the same as of the proper leaves of the species, and by the gradual transitions from the former to the latter in many plants. In the tiirions, or subterranean budding shoots of numerous perennial herbs, and in the unfolding buds of the Lilac and Sweet Buckeye (iEsculus parviflora), every gradation may be traced between bud- scales and foliage, showing that no absolute line can be drawn be- tween them, but that the two are essentially of the same nature, i. e. are different modifications of the same organ. 1 62. Plan of Vegetation. In fact, a simple stem bears nothing but leaves in some form or other, and its branches are only repetitions of itself, following the same laws. The embryo consists of a pri- mary joint of stem crowned with a bud, the first leaves or leaf of which takes the special form of cotyledons ; the following ones de- velop as ordinary foliage, and leaf after leaf, or pair after pair, is formed and elevated upon the successive internodes as the stem is built up. At the close of the growing season, if the stem is to endure, this is terminated, as it began, by a bud ; and the bud-scales, if any, are leaves developed in this peculiar form, subservient to protection alone, and borne upon nodes which are never separated 96 THE STEM. by elongation of the internodes. With the ensuing spring growth recommences, and another set of internodes, and of nodes bearing ordinary leaves, form the second year's growth, like the first ; and so, by annual increments, a simple leafy stem is developed and carried up. Not only is the whole stem growing from 3-ear to year thus composed of a succession of similar growths, each the offspring of the preceding and the parent of the next, but also each annual growth itself consists of a lineal succession of similar parts, viz. of leaf- bearing joints of stem, developed each upon its predecessor, and in turn surmounted by the next in the series. These similar parts, which by their repetition make up the Phamogamous plant, have been termed 163. PhytOllS (from the Greek $vt6v, plant), or plant-elements. The first phyton is the radicle of the embryo, with its cotyledon or pair of cotyledons, from its base developing the root, from above expanding its leaf or pair of leaves (as already described in detail, 119 — 122), and then giving birth to the next phyton, or joint of stem and leaf, and so on, in lineal succession. So that the whole herb, shrub, or tree, as to its upward growth, is a multiplica- tion of the simple plantlet it began with as it developed from the seed. Moreover, any joint of stem, when favorably situated for the pur- pose, may produce secondary roots (142), and thus complete the vegetable individuality, hav- ing all the organs of vegetation (116). 164. The repetition of these similar parts in 137 the direct line, each from the summit of its pre- decessor, builds up a simple or main stem, to which many plants are restricted during the first year's growth, and some, such as Palms and Reeds, throughout their whole existence. Their production from new starting-points gives rise to branches. FIG. 157. Diagram of a simple-stemmed plant, like a Grass, and of the similar parts, or phytons, a to g, of which it is composed. RAMIFICATION. 97 Sect. II. Ramification. 165. Branches spring from lateral or axillary buds. These are new growing points, which habitually appear, or at least may ap- pear, one (or occasionally two or three) in the axil of each leaf, — that is, in the upper angle which the leaf forms with the stem. (See Fig. 153, c, where the point at which the fallen leaves were attached is marked by the broad scar, b, just below the bud.) When these buds grow, they give rise to Branches ; which are repetitions, as it were, of the main stem, growing just as that did from the seed ; ex- cepting merely, that, while that was implanted in the ground, these proceed from the parent stem. The branches are in turn provided with similar buds in the axils of their leaves, capable of developing into branches of a third order, and so on indefinitely, producing the whole ramification of the plant. The ultimate ramifications are termed Branchlets. 166. The arrangement of axillary buds depends upon that of the leaves. When the leaves are opposite (that is, two on each node, placed on opposite sides of the stem), the buds in their axils are consequently opposite ; as in the Maple, Horsechestnut (Fig. 153), Lilac (Fig. 154), &c. When the leaves are alternate, or one upon each node, as in the Apple, Poplar, Oak, Magnolia (Fig. 155), &c., the buds implicitly follow the same arrangement. Branches, there- fore, being developed axillary buds, their arrangement follows that of the leaves. When the leaves are alternate, the branches will be alternate ; when the leaves are opposite, and the buds develop regu- larly, the branches will be opposite. But the perfect symmetry of the ramification, thus provided for, is frequently obscured by the 167. Non-development of some of the Buds. As the original bud of the embryo remains for a time latent in the seed, growing only when a conjunction of favorable circumstances calls its life into action, so also many of the buds of a shrub or tree may remain latent for a long time, and many of them fail to grow at all. In our trees, most of the lateral buds generally remain dormant for the first season : they appear in the axils of the leaves early in summer, but do not grow into branches until the following spring ; and even then only a part of them usually grow. Sometimes the failure occurs without appreciable order; but it often follows a nearly uniform rule in each species. Thus, when the leaves are opposite, there are 9 98 THE STEM. usually three buds at the apex of a branch ; namely, the terminal, and one in the axil of each leaf; but it seldom happens that all three develop at the same time. Sometimes the terminal bud con- tinues the branch, the two lateral generally remaining latent, as in the Horsechestnut (Fig. 153) ; sometimes the terminal one regu- larly fails, and the lateral ones grow, when the stem annually be- comes two-forked, as in the Lilac (Fig. 154). The undeveloped buds do not necessarily perish, but are ready to be called into action in case the others are checked. When the terminal buds are destroyed, some of the lateral, that would else remain dormant, develop in their stead, incited by the abundance of nourishment, which the former would have monopolized. In this manner our trees are soon reclothed with verdure, after their tender foliage and branches have been killed by a late vernal frost, or other injury. And buds which have remained latent for several years occasionally shoot forth into branches from the sides of old stems. Such branch- es, however, more commonly originate from irregular, accidental, or, as they are named 168. Adventitious Buds. It has been already remarked, that roots, although naturally destitute of buds, do yet produce them in certain plants, especially when wounded (139). So likewise do the stems of some shrubs and trees, especially when surcharged with sap, as is commonly seen in Willows and Lombardy Poplars. Here buds break out habitually on the sides of trunks, at least when they are wounded or pollarded, or spring from the cut surface where the bark and wood join. These adventitious buds do not originate from nodes, nor affect any order in their appearance, but are wholly casual as to the point of origin. Thus the predestined symmetry of the branches is obscured or interfered with in two distinct ways ; first, by the failure of a part of the regular buds to develop ; and secondly, by the irregular and casual development of buds from other parts than the axils of the leaves : to which we may add, that great numbers of branches perish and fall away after they have be- gun to grow. There is still another source of irregularity, namely, the production of 1G9. Accessory Buds. These are, as it were, multiplications of the regular axillary bud, giving rise to two, three, or more buds, instead of one ; in some cases situated one above another, in others side by side. In the latter case, which occurs occasionally in the Hawthorn, in certain Willows, in the Maples (Fig. 158), &c, the axillary bud RAMIFICATION. 99 seems to divide into three, or itself give rise to a lateral bud on each side. On some shoots of the Tartarean Honeysuckle (Fig. 160) from three to six buds appear in each axil, one above another, the lower being successively the stronger and earlier produced, and the one immediately in the axil, therefore, grows in preference : oc- casionally two or more of them grow, and superposed accessory branches result. It is much the same in Aristolochia Sipho, except that the uppermost bud is there strongest. So it is in the Butternut (Fig. 159), where the true axillary bud is mi- nute and usually remains latent, while the accessory ones are considerably remote, and the uppermost, which is much the strongest, is far out of the axil ; this usually develops, and gives rise to an extra-axillary branch. 170. Excurrent and Deliquescent Stems. Sometimes the primary axis is prolonged without interruption, by the continued evolution of a terminal bud, even through the whole life of a tree (unless acciden- tally destroyed), forming an undivided 158 159 main trunk, from which lateral branches proceed ; as in most Fir- trees. Such a trunk is said to be excurrent. In other cases the main stem is arrested, sooner or later, either by flowering, by the failure of the terminal bud, or by the more vigorous development of some of the lateral buds ; and thus the trunk is dissolved into branches, or is deliquescent, as in 160 the White Elm and in most of our deciduous-leaved trees. The first naturally gives rise to conical FIG. 158. Branch of Red Maple, -with triple axillary buds, placed side by side. FIG. 159. Piece of a branch of the Butternut, with accessory buds placed one above another : a, the leaf-scar : 6, proper axillary bud : c, d, accessory buds. FIG. 160. Part of a branch of Tartarean Honeysuckle, with crowded accessory buds in each axil. 100 THE STEM. or spire-shaped trees ; the second, to rounded or spreading forms. As stems extend upward and evolve new branches, those near the base, being overshadowed, are apt to perish, and thus the trunk be- comes naked below. This is well seen in the excurrent trunks of Fii's and Pines, which, when grown in forest, seem to have been branchless for a great height. But the knots in the centre of the trunk are the bases of branches, which have long since perished, and have been covered with a great number of annual layers of wood, forming the clear stuff of the trunk. 171. Definite and Indefinite Annual Growth of Branches. In the larger number of our trees and shrubs, especially those with scaly buds, the whole year's growth is either already laid clown rudi- mentally in the bud (159), or else is early formed, and the develop- ment is completed long before the end of summer ; when the shoot is crowned with a vigorous terminal bud, as in the Horsechestnut (Fig. 153) and Magnolia (Fig. 155), or with the uppermost axillary buds, as in the Lilac (Fig. 154) and Elm. Such definite shoots do not die down at all the following winter, but grow on directly, the next spring, from these terminal or upper buds, which are generally more vigorous than those lower down. In other cases, on the contrary, the branches grow onward indefinitely through the whole summer, or until arrested by the cold of autumn : they mature no buds at or near their summit ; or at least the lower and older axillary buds are more vigorous, and alone develop into branches the next spring ; the later-formed upper portion most commonly perishing from the apex downward for a certain length in the winter. The Rose and Raspberry, and among trees the Sumac and Honey Locust, are good illustrations of this sort ; and so are most perennial herbs, their stems dying down to or beneath the surface of the ground, where the persistent base is charged with vigorous buds, well pro- tected by the ground, for the next year's vegetation. 172. Propagation from Bllds. Buds, being, as it were, new indi- viduals springing from the original stem, may be removed and attached to other parts of the parent trunk, or to that of another individual of the same, or even of a different, but nearly related species, where they will grow equally well. This is directly accom- plished in the operation of budding. In ingrafting, the bud is transferred, along Avith a portion of the shoot on which it grew. Moreover, as the cut end of such shoots, when buried in moist and warm soil, will commonly, under due care, send out adventitious KINDS OF STEM AND BRANCHES. 101 roots, they may be made to grow independently, drawing their nourishment immediately from the soil, instead of indirectly through the parent trunk. This is done in the propagation of plants by cuttings. The great importance of these horticultural operations depends chiefly on the well-known fact, that buds propagate indi- vidual peculiarities, which are commonly lost in raising plants from the seed. Sect. III. The Kinds of Stem and Branches. 173. On the size and duration of the stem the oldest and most obvious division of plants is founded, namely, into Herbs, Shrubs, and Trees. 174. Herbs are plants in which the stem does not become woody and persistent, but dies annually or after flowering, down to the ground at least. The difference between annual, biennial, and perennial herbs has already been pointed out (144-146). The same species is so often either annual or biennial, according to cir- cumstances or the mode of management, that it is convenient to have a common name for plants that flower and fruit but once, at whatever period, and then perish: such De Candolle accordingly designated as Monocarpic plants ; while to perennials, whether herbaceous or woody, large or small, he applied the counterpart name of Polycarpic plants, signifying that they bear fruit an indefinite number of times. 175. Ulldershrubs, or suffruticose plants, are woody plants of hum- ble stature, their stems rising little above the surface. If less decidedly woody, they are termed suffrutescent. 176. Shrubs are woody plants, with stems branched from or near the ground, and less than five times the height of a man. Between shrubs and trees there is every intermediate gradation. A shrub which approaches a tree in size, or imitates it in aspect, is said to be arborescent. 177. Trees are woody plants with single trunks, which attain at least five times the human stature. 178. A Culm is a name applied to the peculiar jointed stem of Grasses and Sedges, whether herbaceous, as in most Grasses, or woody or arborescent, as in the Bamboo. 179. A Caudei is a name usually applied to a Palm-stem (Fig. 9* 102 THE STEM. 184), to that of a Tree Fern (Fig. 100), and to any persistent, erect or ascending, root-like forms of main stems. 180. Those stems which are too weak to stand upright, but re- cline on the ground, rising, however, towards the extremity, are said to be decumbent: if they rise obliquely from near the base, they are said to be ascending. When they trail flat on the ground, they are procumbent, prostrate, or running ; and when such stems strike root from their lower surface, as they are apt to do, they are said to be creeping, or repent. They are climbing when they cling to neighboring objects for support; whether by tendrils, as the Vine and Passion-flower, by their leafstalks, as the Virgin's Bower (Clematis), or by aerial rootlets, as the Poison Oak (Rhus) ; and twining, or voluble plants, when they rise, like the Convolvulus, by coiling spirally around stems or other bodies within their reach. Other modifications of the stem or branches have received particu- lar names, some of which mei'it notice from having undoubtedly sug- gested several operations by which the cultivator multiplies plants. 181. A Stolon is a branch which naturally curves or falls down to the ground, where, favored by shade and moisture, it strikes root, and then forms an ascending stem, capable of drawing its nourish- ment directly from the soil, and, by the perishing of the portion which connects it with the parent stem, at length acquiring an entirely separate existence. The Currant, Gooseberry, &c, multi- ply in this way, and doubtless suggested to the gardener the opera- tion of layering ; in which he not only takes advantage of and accelerates the attempts of nature, but incites it in species which do not ordinarily multiply in this manner. 182. A Sucker is a branch of subterranean origin, which, after run- ning horizontally and emitting roots in its course, at length, follow- ing its natural tendency, rises out of the ground and forms an erect stem. The Eose, the Raspberry, and the Mint afford familiar illus- trations, as well as many other species which shoot up stems " from the root," as is generally thought, but really from subterranean branches. Cutting off the connection with the original root, the gardener propagates such plants by division. 183. A Runner, of which the Strawberry furnishes the most familiar example, is a prostrate, slender branch, sent off from the base of the parent stem, which strikes root at its apex, and produces a tuft of leaves ; thus giving rise to an independent plant capable of extend- ing itself in the same manner. RUNNERS, TENDRILS, ETC. 103 184. An Offset is a similar, but short, prostrate branch, with a tuft of leaves at the end, which, resting on the ground, there takes root, and at length becomes independ- ent ; as in the Houseleek. 185. A Tendril is commonly a thread-like, leafless branch, capable of coiling spirally, by which some climbing plants attach themselves to surrounding bodies for support; as in the Grape-vine (Fig. 161). But sometimes tendrils belong to the leaves, as in the Pea; when they are slender prolongations of the leafstalk. Some tendrils cling by hooking their tips around the supporting object. Others, such as those of the Virginia Creeper (Fig. 162, 163), commonly expand the tips of the tendrils into a flat disc, — much as do many aerial rootlets (as those of Ivy) when subservient to the same office, — which firmly ad- 1S1 heres to walls or the bark of trees, thus enabling the plant to ascend and cover their surface. As soon as they are attached, the tendril FIG. 161. End of a shoot of the Grape-vine, with young tendrils. FIG. 162. A portion of a stem of Ampelopsis, or Virginia Creeper, with a leaf and a tendril. FIG. 163. Ends of the latter, enlarged, showing the expanded tips by which they cling. 104 THE STEM. usually shortens itself by coiling spirally, thus drawing up the climbing shoot closer to the supporting object. 186. A Spine Or Thorn is an imperfectly developed, indurated, leaf- less branch of a woody plant, attenuated to a point. The nature of spines is manifest in the Haw- thorn (Fig. 165), not only by their position in the axil of a leaf, but often by producing im- perfect leaves and buds. And in the Sloe, Pear, &c, many of the stinted branches become spinose or spinescent at the apex, tapering off gradually in- to a rigid, leafless point, thus exhibiting every gradation be- tween a spine and an ordinary branch. These spinose branch- es are less liable to appear on the cultivated tree, when duly cared for, such branches being thrown mostly into more vigor- ous growth. In the Hawthorn, the spines spring from the mam axillary bud, while accessory buds (169), one on each side, ap- pear, and one or both grow the 165 next season into an ordinary branch. In the Honey Locust, it is the uppermost of several ac- cessory buds, placed far above the axil, that develops into the thorn (Fig. 164). And here the spine itself branches, and sometimes be- comes extremely compound. Sometimes the stipules of the leaves develop into spines, as in the Prickly Ash. Sometimes the leaf it- self is developed as a spine ; of which the Barberry affords a familiar example. When the spine is situated in the axil of a leaf or a leaf- scar, it is necessarily of the nature of a branch. When it bears a FIG. 164. Branching thorn of the Honey Locust (Gleditschia), an indurated branch devel- oped from an accessory bud produced above the axil, a, Three buds under the base of the leafstalk, brought to view in a section of the stem and leafstalk below. FIG. 165. Thorn of the Cockspur Thorn, developed from the central of three axillary buds ; one of the lateral buds is seen at its base. ITS SUBTERRANEAN MODIFICATIONS. 105 bud oi- branch in its axil (as in the Barberry, Fig. 296), it must be of the nature of a leaf. 187. The Subterranean Modifications of the Stem are scarcely less numerous and diverse than the aerial ; but they may all be reduced to a few principal types. They are perfectly distinguishable from roots by producing regular buds, or by being marked with scars, which indicate the former insertion of leaves, or furnished with scales, which are the rudiments or the vestiges of leaves. All the Scaly roots of the older botanists are therefore forms of the stem or branches, with which they accord in every essential respect. So, likewise, what are popularly called Creeping roots are really subter- ranean branches ; such as those of the Mint, and of most Sedges and Grasses. Some of these, such as the Carex arenaria (Fig. 166) of Europe, render important service in binding the shifting sands of the sea-shore. Others, like the Couch-Grass, are often very trouble- some to the agriculturist, who finds it next to impossible to destroy them by the ordinary operations of husbandry ; for, being furnished with buds and roots at every node, which are extremely tenacious of life, when torn in pieces by the plough, each fragment is only placed in the more favorable condition for becoming an independent plant. The Nut-Grass (Cyperus Hydra), an equally troublesome pest to the planters of Carolina and Georgia, is similarly constituted ; and FIG. 166. Creeping subterranean stem of Carex arenaria. FIO. 167. Rhizoma of Diphylleia cymosa, showing six years' growth, and a bud for the seventh : a, the bud : b, base of the stalk of the current year : c, scar left by the decay of the annual stalk of the year before ; and beyond are the scars of previous years. 106 THE STE3I. besides, the interminable subterranean branches bear tubers, or reservoirs of nutritive matter, in their course, which have still greater powers of vitality, as they contain a copious store of food for the development of the buds they bear. The name of 188. Rhizoma or RootstOCk is applied in a general way to all these perennial, horizontally elongated, more or less subterranean, root- like forms of the stem; and more particu- larly to those that are consid- erably thick- ened by the ac- 163 cumulation of starch or other forms of nutritive matter in their tissue, such as the so-called roots of Ginger, of the Iris or Flower-de-luce (Fig. 291), of the Calamus or Sweet Flag, and of the Blood- root. They grow after the manner of ordinary stems, advancing from year to year by the annual development of a bud at the apex, and emitting roots from the under side of the whole surface ; thus established, the older portions die and decay, as corresponding additions are made to the opposite growing extremity. Each year's growth is often marked, as in some species of Iris (Fig. 291), by a narrowing at the place r ( where the growth of the season is suspended, followed by an enlargement where it recom- mences ; or else, as in the curious Diphylleia of the Alleghany Mountains (Fig. 1G7), and the Polygonatum or Solomon's Seal (Fig. 168), it is more indelibly stamped by an im- pressed circular scar (which has been likened to the impression of a seal), left annually, in autumn, by the death and separation from the perennial rootstock of the herbaceous stalk of the season which bore the foliage and blossoms. In Diphylleia the growth is so slow, and the ascending stems so thick, that the scars of successive years are FIG. 168. Rootstock of Polygonatum or Solomon's Seal, with the terminal bud, the base of the stalk of the season, and three scars from which the latter has separated in as many former FIG. 169. The short and upright rootstock of Trillium erectum, or Birthroot, with its ter- minal bud. ROOTSTOCKS AND TUBERS. 107 nearly in contact (Fig. 167). In the very short and slow-growing rootstock of Trillium (Fig. 169), the base of the leaf-bearing and flowering stem of the season surrounds and covers the terminal bud. In our common Dentaria or Toothwort, and in Hydrophyllum, the base of this annual stalk or of the leafstalks partakes in the thicken- ing, and persists as a part of the rhizoma, in the form of fleshy scales or tooth-shaped processes. In other scaly rootstocks, these persist- ent bases of the leaves are thin, and more like bud-scales, and slowly decay after a year or two. All such markings are vestiges of leaves, &c, or the scars from which they have fallen or decayed away, and indicate the nodes. They show that the body that bears them belongs to the stem ; and not to the root, which is wholly leafless. Root-stocks branch, just as other stems do, by the development of lateral buds from the axils of their scales or leaves. They serve as a reservoir of nourishing matter, for the maintenance of the an- nual growth, in the same manner as do thickened roots (145, 146). When such subterranean stems are thickened at the apex only, they produce 189. A Tuber. This is usually formed by the enlargement of the growing bud of a subterranean branch, and the deposition of starch, &c. in its tissue. This deposit serves for the nourishment of the buds (eyes) which it involves, when they develop the following year. The common Potato offers the most familiar example ; and it is FIG. 170. Base of the stem of the Jerusalem Artichoke (Uelianthus tuberosus), with its tubers. FIG. 171. A monstrous branch or bud of the Potato, aboye ground, showing a transition to the tuber. (From the Gardener's Chronicle.) 108 THE STEM. very evident on inspection of the growing plant, that the tubers belong to branches, and not to the roots. The nature of the potato is also well shown by an accidental case (Fig. 171), of the buds or branches above ground thickened and manifested a strong tendency to develop in the form of tubers. By heaping the soil around the stems, the number of tuberiferous branches is increased. The Jerusalem Artichoke also affords a familiar il- lustration of the tuber (Fig. 170). A tuber of a rounded form, and with few buds, or a rhizoma somewhat shorter and thicker than that in Fig. 169, effects a transition to 190. A Corm (Cormus), or Solid Bulb. This is a fleshy subterranean stem, of a rounded or oval figure and a compact texture ; as in the Arum or Indian Turnip (Fig. 175), the Colchicum, the Crocus (Fig. 180, 181, 182), the Cyclamen* &c Corms have been termed solid bulbs. But the principal bulk of a true bulb consists not of stem but of leaves. * The flattened conn of Cyclamen originates from the dilatation of the radicle itself. In the Turnip, Beet, and Radish (Fig. 138), this also enlarges with the proper root, the upper part of which accordingly partakes of the nature of the stem. FIG. 172. The scaly bulb of a Lily. 173. A vertical section of the same, forming the an- nual stalk. 174. Axillary bulblets of Lilium bulbiferum. 175. Corm of Arum triphyllum. FIG. 176. A radical leaf of the White Lily, with its base thickened into a bulb-scale, cut across below to show its thickness. BULBS AND BULBLETS. 109 191. A Bulb is a permanently abbreviated stem, mostly shorter than broad, and clothed with scales, which are imperfect and thick- ened leaves, or more commonly the thickened and persistent bases of ordinary leaves (Fig. 176). In other words, it is a scaly and usually subterranean bud, with thickened scales, and a depressed axis which never elongates. Its centre or apex develops upward the herbaceous stalk, foliage, and flowers of the season, and beneath emits roots. In the bulb, the thickening by the deposition of nutri- tive matter, stored for future use, takes place in the leaves or scales it bears, instead of the stem itself, as in the preceding forms. The scales are sometimes separate, thick, and narrow, as in the Scaly bulb of the Lily (Fig. 172) ; sometimes broad and in concentric layers, as in the Tunicated bulb of the Onion (Fig. 177). 192. BulbletS are small aerial bulbs, or buds with fleshy scales, which arise in the axils of the leaves of several plants, such as the common Lilium bulbiferum of the gardens (Fig. 174), and at length separate spontaneously, falling to the ground, where they strike root, and grow as independent plants. In the Onion, and other species of Album, bulblets are often produced in place of flower-buds. These plainly show the identity of bulbs with buds. 193. All these extraordinary, no less than the ordinary, forms FIG. 177. Section of a tunicated bulb of the Onion. FIG. 178. Vertical section of the bulb of the Tulip, showing its stem (a) and buds (b, c). FIG. 179. Bulb of a Garlic, with a crop of young bulbs. FIG. 180. Vertical section of the corm of Crocus : a, new buds. FIG. 181. Vertical section of the corm of Colchicum, with the withered corm of the pre- ceding (a), and the forming one (c) for the ensuing year. 10 110 THE STEM. of the stem, grow and branch, or multiply, by the development of terminal and axillary buds. This is perfectly evident in the rhizoma and tuber, and is equally the case in the corm and bulb. The stem of the bulb is usually reduced to a mere plate (Fig. 178, a), which produces roots from its lower surface, and leaves or scales from the upper surface. Besides the terminal bud (c), which usually forms the flower-stem, lateral buds (b, b) are produced in the axils of the leaves or scales. One or more of these may develop as flowering stems the next' season, and thus the same bulb survive and blossom from year to year ; or these axillary buds may themselves become bulbs, feeding on the parent bulb, which in this way is often con- sumed by its own offspring, as in the Garlic (Fig. 179) ; or, finally separating from the living parent, just as the bulblets of the Tiger Lily fall from the stem, they may form so many independent indi- viduals. So the corm of the Crocus (Fig. 182, 182") produces one or more new ones, which feed upon and exhaust it, and take its place ; and the shrivelled remains of the old corm may be found underneath the new, the next season. The corm of Colchicum (Fig. 181) produces a new bud on one side at the base, and is consumed by it in the course of the season ; the new one, after flowering by its terminal bud, is in turn consumed by its own offspring; and so on. In Fig. 181, we have at one view, a, the dead and shrivelled corm of the year preceding ; b, that of the present season (a vertical section) ; and c, *S2 ° the nascent bud for the growth of the ensuing season. Many of the forms which the stem assumes when above ground differ as much from the ordinary appearance as do any of these subterranean kinds, and, in fact, imitate their peculiarities ; as, for example, the globular Melon-Cactus and Mamillaria, the colum- nar Cereus, and the jointed Opuntia or Prickly Pear. These are remarkably 194. Consolidated Forms Of Vegetation. While ordinary plants are constructed on the plan of great expansion of surface, these are FIG. 182. Corm of Crocus, the few thin enveloping scales removed, showing the shrivelled vestige of the last year's corm at the base, and buds developing into new ones on various parts of its surface. 182 Q . Vertical section of a similar corm, with a terminal and one lateral bud. CONSOLIDATED FORMS OF VEGETATION. Ill formed on the plan of the least possible amount of surface in pro- portion to their bulk. A green rind serves the purpose of foliage ; but the surface is as nothing compared with an ordinary leafy plant of the same amount of vegetable material. This consolidation is carried to the extreme in the Melon-Cactus, Mamillaria, and the like, of globular or corm-like shapes ; their spherical figure being that which exposes the least possible part of the bulk to the air. Such plants are evidently adapted and designed for very dry regions; and in such only are they naturally found. Similarly, bulbous and corm-bearing plants, and the like, are a form of vege- tation which in the growing season may in the foliage expand a large surface to the air and light, while during the period of rest the living vegetable is reduced to a globular or other form of the least surface ; and this is protected by its outer coats of dead and dry scales, as well as by its subterranean situation ; — thus exhibit- ing another and very similar adaptation to a season of drought. And such plants mainly belong to countries (such as Southern Africa, and parts of the interior of Oregon and California) which have a long hot season, during which little or no rain falls, when, their stalks and foliage above and their roots beneath being early cut off by drought, the plants rest securely in their compact bulbs, filled with nourishment, and retain their moisture with great tenacity, until the rainy season returns. Then they shoot forth leaves and flowers with wonderful rapidity, and what was perhaps a desert of arid sand becomes green with foliage and gay with blos- soms, almost in a day. This will be more perfectly understood when the nature and the use of foliage shall have been more fully considered. Sect. IV. The Internal Structure op the Stem in General. 195. Having considered the various external forms and appear- ances which the stem exhibits, and its mode of increase in length, our attention may now be directed to its internal structure, and its mode of increase in diameter. 196. The stem embraces in its composition the various forms of elementary tissue that have already been described (Chap. I., Sect. II., III.) ; namely, ordinary cells, woody fibre, and vessels. At 112 THE STEM. first, indeed, it consists entirely of parenchyma (51), which pos- sesses much less strength and tenacity than woody tissue, and is therefore inadequate to the purposes for which the stem, in all the higher plants, is destined. The stem of a Moss or a Liverwort is, in fact, composed of ordinary cellular tissue alone ; and is therefore weak and brittle, well enough adapted to plants of humble size, but not for those which attain any considerable height. Accord- ingly, as soon as the stems of Phamogamous plants begin to grow, and in proportion as the leaves are developed, woody mingled with vascular tissue is introduced, to afford the requisite toughness and strength, and to facilitate the rise of the ascending sap. If the wood accumulates only to moderate extent in proportion to the parenchyma, the stem remains herbaceous (174) ; if it predominates and continues to accumulate from year to year, the proper woody trunk of a shrub or tree is formed. 197. The cellular part of the stem grows with equal readiness, in whatever direction the forces of vegetation act. It grows verti- cally, to increase the stem in length, and horizontally, to increase its diameter. Into this the elongated cells that form the woody tissue and ducts are introduced vertically ; they run lengthwise through the stem and branches. Hence, the latter has been called the longitudinal, vertical, or perpendicular system (56, 64) ; and the cellular part, the horizontal system of the stem. Or the stem may be compared to a web of cloth; the cellular system forming the woof, and the woody, the warp. 198. The diversities in the internal structure of the stem are principally owing to the different modes in which the woody or vertical system is imbedded in the cellular. These diversities are reducible to two general plans ; upon one or the other of which the stems of all Flowering plants are constructed. Not only is the difference in structure quite striking, especially in all stems more than a year old, but it is manifested in the whole vegetation of the two kinds of plants, and indicates the division of Phamogamous plants into two great classes, recognizable by every eye ; which, in their fully developed forms, may be represented, one by the Oak and other trees of our climate, the other by the Palm (Fig. 181). 199. The difference between the two, as to the structure of their stems, is briefly and simply this. In the first, the woody system is deposited in annual concentric layers between a central pith and an exterior bark; so that a cross-section presents a series of rings or ITS INTERNAL STRUCTURE. 113 circles of wood, surrounding each other and a distinct pith, and all surrounded by a separable bark. This is the plan, not only of the Oak, but of all the trees and shrubs of the colder climates. In the second, the woody system is not disposed in layers, but consists of separate bundles or threads of woody fibre, &c, running through the cellular system without apparent order ; and presenting on the cross- section a view of the divided ends of these threads in the form of dots, diffused through the whole ; but with no distinct pith, and no bark which is at any time readily separable from the wood. The appearance of such a stem, both on the longitudinal and the cross- section, is shown in Fig. 183 ; it may also be examined in the Cane or Rattan, the Bamboo, and in the annual stalk of Indian Corn or of Asparagus. That of ordinary wood of the first sort is too famil- iar to need a pictorial illustration. 200. Exogenous Structure. The stem, in the first case, increases in diameter by the annual formation of a new layer of wood, which is deposited between the preceding layer and the bark ; that is, the wood increases by annual additions to its outside. Hence, such stems are said to be Exogenous ; and plants whose stems grow in this way are called Exogenous Plants, or briefly Exogens ; that is, as the term literally signifies, outside-growers. 201. Endogenous Structure. In the second case, the new woody matter is intermingled with the old, or deposited towards the centre, which becomes more and more occupied with the woody threads as the stem grows older ; and increase in diameter, so far as it depends on the formation of new wood, generally takes place by the gradual dis- tention of the whole. Accordingly, these stems are said to exhibit the Endoge- nous structure or growth ; and such plants 1S3 are called Endogenous Plants, or Endogens ; literally, tiiside- groivers. 202. The two great classes of Phaenogamous plants, indicated by this' difference in the stem, are distinguishable even in the embryo state, by differences quite as marked as those which prevail in their Avhole port and aspect. The embryo of all plants that have en- dogenous stems bears only a single cotyledon ; hence, Endogens are also called Monocotyledonous Plants (128). The embryo of FIG. 183. Section (longitudinal and transverse) of a Palm-stem. 10* 114 THE STEM. plants with exogenous stems bears a pair of cotyledons and unfolds a pair of seed-leaves in germination (Fig. 106, 125) ; hence, Exogens are likewise called Dicotyledonous Plants. Sect. V. The Endogenous or Monocotyledonous Stem. 208. Endogens, or Inside-growers, although they have many humble representatives in Northern climes, yet only attain their full characteristic devel- opment, and display their noble arbores- cent forms, under a tropical sun. Yet Palms — the type of the class — do ex- tend as far north in this country as the coast of North Caro- lina (the natural lim- it of the Palmetto, Fig. 184) ; while in Europe the Date and the Chamasrops thrive in the warm- er parts of the European shore of the Mediterranean. The manner of their growth gives them astrik- VV ".,/.V ing appear- ance ; their t j trunks being unbranehed, cylindrical columns, rising majestically to the height of from thirty to one hundred and fifty feet, and crowned at the summit with a simple cluster of peculiar foliage. Then* internal structure is equal- ly different from that of ordinary wood. FIG. 184. The Chamaerops Palmetto, in various stages, and the Yucca Dracouis. M*^ m ENDOGENOUS STRUCTURE. 115 204. The stem of an Endogen, as already explained (199), offers no manifest distinction into bark, pith, and wood ; and the latter is not composed of concentric rings or layers. But it consists of bundles of woody and vascular tissue, in the form of fibres or threads, which are imbedded, with little apparent regularity, in cellular tissue ; and the whole is enclosed in an integument, which does not strictly resemble the bark of an Exogenous plant, inasmuch as it does not increase by layers, and is never separable from the wood. The fibrous bundles which compose the wood, and which consist of a mass of woody fibres surrounding several vessels, are distributed throughout the cellular system of the stem, but most abundantly towards the circumference. Each bundle usually contains all the elements of the wood of the exogenous stem ; namely, vessels, proper woody tissue, and bast-cells. The bundles often may be traced directly from the base of the leaves down through the stem, some of them to the roots in a young plant, while others, curving outwards, lose themselves in the cortical integument, or rind. As the stem increases, new bundles, springing from the bases of more recently developed leaves, are at first directed towards the centre of the stem, along which they descend for some distance, growing more slender in their course, and then, curving out- wards, mostly terminate hi the rind. It is partly in consequence of the co- hesion of these obliquely descending fibres to the false bark, that the latter cannot, as in Exogens, be separated from the wood beneath. The manner in which the woody threads are consequently interwoven is shown in Fig. 185. The Palm-like Yuccas of the Southern States offer beautiful illustrations of the kind. 205. Endogenous stems, instead of having the oldest and hardest wood at the centre and the newest and softest at the circumference, as in ordinary trees, are softest towards the centre and most compact at the circumference. They increase in diameter with the increas- ing number of woody bundles (which multiply as new leaves are FIG. 185. Vertical ami transverse section of a young endogenous stem, showing the curv- ing of the fibres. 116 THE STEM. produced), as long as the rind is capable of distention. In some instances, as in the arborescent Yuccas and the Dracaenas or Dragon- trees, the rind remains soft and capable of unlimited growth ; but in the Palms, and in most woody Endogens, it soon indurates, and the stem consequently increases no further in diameter. The wood of the lower part of such stem is more compact than the upper, being more filled with woody bundles, and the rind is firmer, from the greater number of ligneous fibres which terminate in it, and from its proper induration. 206. Palms generally grow from the terminal bud alone, and perish if this bud be destroyed ; they grow slowly, and bear their foliage in a cluster at the summit of the trunk, which consequently forms a simple cylindrical column. But in some instances two or more buds develop, and the stem branches, as in the Doum Palm of Upper Egypt, and in the Pandanus, or Screw-Pine (Fig. 140), which belongs to a family allied to Palms : in such cases the branches are cylindrical. But when lateral buds are freely devel- oped (as in the Asparagus), or the leaves are scattered along the stem or branches (as in the Bamboo, Maize, &c), these taper up- wards, just as in Exogens. A particular comparison of the structure and growth of the Endogenous stem with the Exogenous cannot be instituted until the latter is explained in detail. Sect. VI. The Exogenous or Dicotyledonous Stem. 207. Since the Exogenous class is by far the larger in every part of the world, and embraces all the trees and shrubs with which we are familiar in the cooler climates, the structure of this kind of stem demands more detailed notice. To obtain a true and clear idea of its internal structure, we should commence at its origin and follow the course of development. 208. In the embryo, or at least at some period antecedent to germination, the rudimentary stem is entirely composed of paren- chyma. But as soon as it begins to grow, some of the cells begin to lengthen into tubes, to be marked with transverse bars or spiral lines, and thus give rise to ducts or vessels (57 - 60) ; these form a small and definite number of bundles or threads, say four equidistant ones in the first instance, as in the Sugar Maple : surrounding these, other slender cells of smaller calibre, and destitute of markings, EXOGENOUS STRUCTURE. 117 soon appear, and form the earliest woody tissue. As the rudiments of the next internode and its leaves appear, two or four additional threads of vascular tissue appear in the stem below, in the paren- chyma between the earliest ones, and are equally surrounded with forming woody tissue. At an early stage, therefore, the developing stem is seen to be traversed by several bundles of woody tissue, with some vessels imbedded ; and these, as they increase and enlarge, run together so as to make up a woody zone (or, as seen in the cross- section, a ring), enclosing the central part of the pai*enchyma within it, and itself enclosed by the external parenchyma. Thus a zone or layer of wood is formed, which is so situated in the original homo- geneous cellular system as to divide it into two parts ; namely, a central portion, which forms the pith, and an exterior portion, which belongs to the bark. The whole is of course invested by the skin or epidermis, which covers the entire surface of the plant. The way in which the layer of wood thus originates is somewhat rudely illustrated by the annexed diagrams (Fig. 186- 188). The several woody masses, or wedges, are separated from each other by lines or bands of the original cellular tissue, which pass from the pith to the bark, and which necessarily become narrower and more numerous as the woody bundles or wedges increase in size and number. These bands are the 209. Medullary Rays. These form the radiating lines that the cross-section of most exogenous wood so plainly exhibits, especially that of the Oak, Plane, &c. They consist of parenchyma, more FIG. 186. Plan of a cross-section of a forming seedling stem, showing the manner in which the young wood is imbedded in the cellular system. FIG. 187. The same at a later period, the woody bundles increased so as nearly to fill the circle. FIG. 188. The same at the close of the season, where the wood has formed a complete circle, separating the pith from the bark, except that they are still connected by narrow por- tions of the cellular system (the medullary rays) which radiate from the pith to the bark. 118 THE STEM. or less flattened by the pressure of the woody wedges, and they serve to keep up the communication between the pith and the bark. 210. The First Year's Growth of an exogenous stem accordingly con- sists of three principal parts, viz. : 1st, a central cellular portion, or Pith; 2d, a zone of Wood; and 3d, an exterior cellular portion, or Bark. These several parts are displayed in Fig. 189-191, as they occur in a woody stem a year old. 211. The Pith (Me- dulla) consists en- tirely of soft cellular tissue, or parenchy- ma* (51), which is at first gorged with sap. Many stems expand so rapidly in diameter during their early growth, that they become hollow, the pith being torn away by the disten- tion, and its remains forming a mere lin- ing to the cavity. In the "Walnut and the Poke (Phytolac- * In rare instances a few threads of woody tissue and vessels are found dis- persed through the pith, presenting a somewhat remarkable anomaly. This occurs in Aralia racemosa, and more strikingly in Oxybaphus, Mirabilis or Four-o'clock, and other Nyctaginaceae. FIG. 189. Longitudinal and transverse section of a stem of the Soft Maple (Acer dasycar- pum), at the close of the first year's growth ; of the natural size. FIG. 190. Portion of the same, magnified, showing the cellular pith, surrounded by the wood, and that enclosed by the bark. FIG. 191. More magnified slice of the same, reaching from the bark to the pith : a, part of the pith ; b, vessels of the medullary sheath ; c, the wood ; rfrf, dotted ducts in the wood ; ee, annular ducts ; f, the liber, or inner fibrous bark ; g, the cellular envelope, or green bark ; A, the corky envelope ; i, the skin or epidermis ; k, one of the medullary rays, seen on the trans- verse section. EXOGENOUS STRUCTURE. 119 ca) it is early separated into a series of horizontal plates. As the stem groAvs older the pith becomes dry and light, its cells filled with air only ; and then it is of no further use to the plant. 212. Tlie Wood consists of proper Avoody tissue (53), among which the vascular is more or less copiously mingled, principally in the form of dotted ducts (Fig. 191, d), or occasionally some annular ducts (e), &c. The dotted ducts are of so considerable calibre, that they are conspicuous to the naked eye in many ordinary kinds of Avood, especially AA'here they are accumulated in the inner portion of each layer, as in the Chestnut and Oak. In the Maple, Plane, &c, they are rather equably scattered through the annual layer, and are of a size so small, that they are not distinguishable by the naked eye. — Next the pith, i. e. in the very earliest formed part of the AA T ood, some spiral ducts are uniformly found (Fig. 191, b), and this is the only part of the exogenous stem in whieh these ordinarily occur. They may be detected by breaking a woody tA\ r ig in tAA'o, after divid- ing the bark and most of the AA r ood by a circular incision, and then pulling the ends gently asunder, AA'hen their spirally coiled fibres are readily draAvn out as gossamer threads. As these spiral ducts form a circle immediately surrounding the pith, they form AA'hat has been termed the Medullary Sheath. This is no special organ, and hardly requires a special name, since it merely represents the earli- est-formed vascular tissue of the stem. 213. The vertical section in Fig. 191 divides one of the woody wedges ; and therefore the medullary rays do not appear. But in FIG. 192. Vertical section through the wood of a branch of the Maple, a year old ; so as to show one of the medullary rays, passing transversely from the pith (p) to the bark (b): mag- nified. But a section can seldom be made so as to show one unbroken plate stretching across the wood, as in this instance. FIG. 193. A vertical section across the ends of the medullary rays ; magnified. 120 the stem:. the much more magnified Fig. 192, the section is made so as to show the surface of one of these plates, and one of the Medullary Rays passing horizontally across it, connecting the pith (p) with the bark (b). These medullary rays form the silver-grain, (as it is termed,) which is so conspicuous in the Maple, Oak, &c, and which gives the glimmering lustre to many kinds of Avood when cut in this direction. But a section made as a tangent to the circum- ference, and therefore perpendicular to the medullary rays, brings their ends to A'ieAV, as in Fig. 193 ; much as they appear Avhen seen on the surface of a piece of Avood from which the bark is stripped. They are here seen to be composed of parenchyma, and to represent the horizontal system of the Avood, or the woof, into which the ver- tical Avoody fibre, &c, or ivarp, is interwoven. The inspection of a piece of oak or maple A\ r ood at once sIioavs the pertinency of this illustration. 214. The Bark, in a stem of a year old, must next be considered. At first it consists of simple parenchyma, undistinguishable from that of the pith, except that it assumes a green color when exposed to the light, from the production of chlorojihyll (92) in its cells. But during the formation of the Avood of the season, an analogous forma- tion occurs in the bark. The inner portion, next the Avood, has woody tissue formed in it, and becomes 215. The Liber, or Inner Bark (Fig. 191,/). The fibre-like cells, which give to the inner bark of those plants that largely contain them its principal strength and toughness, are of the kind already described under the name of bast-cells or bast-tissue (55). They are remarkable for their length, flexibility, and the great thickness of their Avails. They form in bundles, or in bands separated by exten- sions of the medullary rays, one accordingly corresponding to each of the Avoody plates or Avedges ; or sometimes (as in Negundo, Fig. 194, 195) they are confluent into an unbroken circle round the Avhole circumference. Complete and well-developed liber, like that of the BassAVood, consists of three elements, viz.: 1. bast-cells or fibres ; 2. large and more or less elongated cells, Avith thinner Avails variously marked Avith transparent spots, appearing like perforations, and usually traversed by an exceedingly minute net-work ; and 3. cells of parenchyma. The liber has received the technical name of Endophlceuai (literally inner bark). In most Avoody stems the exterior part of the bark, in Avhich no woody tissue occurs, is early distinguishable into tAvo parts, an inner and an outer. The former is EXOGENOUS STRUCTURE. 121 216. The Cellular Envelope, or Green Layer (Fig. 191, g), also called, from its intermediate position, the Mesophloeum. This is com- posed of loose parenchyma, with thin walls, much like the green pulp of leaves, and containing an equal abundance of chlorophyll. It is the only part of the bark that retains a green color. In woody steins this is soon covered with 217. The Corky Envelope, or Epiphlosum (Fig. 191, b), which gives to the twigs of trees and shrubs the hue peculiar to each spe- cies, generally some shade of ash-color or brown, or occasionally of much more vivid tints. It is this tissue, which, taking an unusual development, forms the cork of the Cork-Oak, and those corky ex- pansions of the bark which are so conspicuous on the branches of Wmmm r? o m FIG. 194. Portion of a transverse section, and 195, a corresponding vertical section, magni- fied, reaching from the pith,p, to the epidermis, e, of a stem of Negundo, a year old : B, the bark ; W, the wood ; and C, the cambium-layer, as found in February. The references are in the text above ; except mr, portion of a medullary ray, seen on the vertical section, -where it runs into the pith : dd, dotted ducts : d, the inner part of the cambium-layer, which begins the new layer of wood. In this tree, we find a thick layer of parenchyma (I) inside of the bast- tissue, and therefore belonging to the liber. No bast-tissue is formed in it the second year. 11 122 THE STEM. the Sweet Gum (Liquidambar), and on some of our Elms (Ulmus alata and racemosa) . It also forms the paper-like, exfoliating layers of Birch-bark. It is composed of laterally flattened parenchymatous cells, much like those of the Epidermis (69, Fig. 191, i), Avhich directly overlies it, and forms the skin or surface of the stem. 218. The elements of an exogenous stem of a year old, especially in a woody plant, accordingly are these, proceeding from the centre towards the circumference : — I. In the Wood : 1. The Pith, belonging to the cellular system (Fig. 194, 195, p). 2. The Medullary Sheath, ms, ) which belong to the woody or 3. The Layer of Wood, W, w, ) longitudinal system. 4. The Medxdlary Rays, mr, a part of the cellular system. II. In the Bark : 5. The Liber, I ; its bast-tissue, b, belongs to the woody system. 6. The Outer Baric, belonging wholly to the cellular system, and composed of two parts, viz. : 1st, the Green or Cellular En- velope, ge, and 2d, the Corky Envelope, ce. 7. The Epidermis, e, or skin, which invests the whole. 219. An herbaceous stem does not essentially differ from a woody one of this age, except that the wood forms a less compact or thinner zone ; and the whole perishes, at least down to the ground, at the close of the season. But a woody stem makes provision for contin- uing its growth the second year. As the layer of wood continues to increase in thickness throughout the season, by the multiplication of cells on its outer surface, between it and the bark, and Avhen growth ceases this process of cell-multiplication is merely suspended, so there is always a zone of delicate young cells interposed between the wood and the bark. This is called the 220. Cambium-Layer, (Fig. 194, 195, C). It is charged with or- ganizable matter (protoplasm, dextrine, &c.) in the form of a mu- cilage, which is particularly abundant in the spring when growth recommences. This mucilaginous matter was named Cambium by the older botanists ; who supposed — as is still generally thought — that the bark, then so readily separable, really separated from the wood in spring, that a quantity of rich mucilaginous sap was poured out between them, and that this sap, or cambium, was organized into a tissue, the inner part becoming new wood, the outer, new bark. But delicate slices will show that there is then no more inter- ruption of the wood and inner bark than at any other season ; that EXOGENOUS STRUCTURE. 123 the two are always organically connected by an extremely delicate tissue of young and vitally active cells, just in the state in which they multiply by division (33). The bark, indeed, is very readily detached from the wood in spring, because the cambium-layer is then gorged with sap ; but the separation is effected by the rending of a delicate forming tissue. And if some of this apparant mucilage be scraped off from the surface of the wood, and examined under a good microscope, it will be seen to be a thin stratum of young wood-cells, with the ends of medullary rays here and there interspersed, and appearing much as in Fig. 193, only the young wood-cells are mostly shorter. The inner portion of the cambium-layer is therefore nas- cent Avood, and the outer is nascent bark. And it is by the growth of the cambium-layer, renewed year after year, that the 221. Annual Increase Of tllC Wood of Exogenous plants is effected. As the cells of this layer multiply, the greater number lengthen ver- tically into prosenchyma or woody tissue ; while some are trans- formed into ducts, and others, remaining as parenchyma, continue the medullary rays or commence new ones. In this way a second layer of wood is formed the second season, over the whole surface of the former layer and between it and the bark, and continuous with the woody layer of the new roots below and of the leafy shoots of the season above. Each succeeding year another layer is added to the wood in the same manner, coincident with the growth in length by the development of the buds. A cross-section of an exogenous stem, therefore, exhibits the wood disposed in concentric rings between the bark and the pith ; the oldest lying next the latter, and the youngest occupying the circumference. Each layer being the pro- duct of a single year's growth, the age of an exogenous tree may, in general, be correctly ascertained by counting the rings in a cross- section of the trunk.* * The annual layers are most distinct in trees of temperate climates like ours, where there is a prolonged period of total repose, from the winter's cold, fol- lowed by a vigorous resumption of vegetation in spring. In tropical trees they are rarely so well defined ; but even in these there is generally a more or less marked annual suspension of vegetation, occurring, however, in the dry and hotter, rather than in the cooler season. There are numerous cases, moreover, in which the wood forms a uniform stratum, whatever be the age of the trunk, as in the arborescent species of Cactus ; or where the layers are few and by no means corresponding with the age of the trunk, as in the Cycas. In many woody climbing or twining stems, such as those of Clematis, Aristo- 124 THE STEM. 222. The Limitation of the Annual Layers results from two or more causes, separate or combined. In oak and chestnut wood, and the like, the layers are strongly defined by reason of the accumulation of the large dotted ducts, here of extreme size and in great abundance, in the inner portion of each layer, where their open mouths on the cross-section are conspicuous to the naked eye, making a strong con- trast between the inner porous, and the exterior solid part of the successive layers. In Maple and Beech wood, however, the ducts are smaller, and are dispersed throughout the whole breadth of the layer ; and in coniferous wood, viz. that of Pine, Cypress, &c, there are no ducts at all, but only a uniform woody tissue of a peculiar sort (46, 54). Here the demarcation between two layers is owing to the greater fineness of the wood-cells formed at the close of the season, viz. those at the outer border of the layer, while the next layer begins, in its vigorous vernal growth, with much larger cells, thus marking an abrupt transition from one layer to the next. Be- sides being finer, the last wood-cells of the season are often flattened laterally, more or less. 223. Each layer of wood, once formed, remains unchanged in posi- tion and dimensions. But in trunks of considerable age, the older layers generally undergo more or less change in color and density, distinguishing the Avood into two parts, viz. 224. Sap-WOOtl and Heart-WOOd. In the germinating plantlet and in the developing bud, the sap ascends through the whole tissue, of whatever sort ; at first through the parenchyma, for there is then no other tissue ; and the transmission is continued through it, especially through its central portion, or the pith, in the growing apex of the stem throughout. But in the older parts below, the pith, soon drained of sap, becomes filled with air in its place, and thenceforth it bears no part in the plant's nourishment. As soon as wood-cells and ducts are formed, they take an active part in the conveyance of sap ; lochia Sipho, and Mcnispermum Canadcnse, the annual layers are rather obscure- ly marked, while the medullary rays are unusually broad ; and the wood therefore forms a series of separable wedges disposed in a circle around the pith. In the stem of one of our Trumpet-creepers (the Bignonia capreolata) the annual rings, after the first four or five, are interrupted in four places, and here as many broad plates of cellular tissue, belonging properly to the bark, are interposed, passing at right angles to each other from the circumference towards the centre, so that the transverse section of the wood nearly resembles a Maltese cross. But these are all exceptional cases, which scarcely require notice in a general view. SAP-WOOD AND HEART-WOOD. 125 for which their tubular and capillary character is especially adapted. But the ducts in older parts, except when gorged with sap, contain air alone ; and in woody trunks the sap continues to rise year after year, to the places where growth is going on, mainly through the proper woody tissue of the wood. In this transmission the new layers are most active, and these are in direct communication with the new roots on the one hand and with the buds or shoots and leaves of the season on the other. So, by the formation of new annual layers out- side of them, the older ones are each year removed a step farther from the region of growth; or rather the growing stratum, which connects the fresh rootlets that imbibe with the foliage that elabo- rates the sap, is each year removed farther from them. The latter, therefore, after a few years, cease to convey sap, as they have long FIG. 196. Magnified cross-section of a portion of woody tissue of White Oak, a year old. 197. A longitudinal as well as cross section of the same, a little higher magnified, a, a, Por- tions of one of the smaller medullary rays. FIG. 198. Magnified cross-section of woody tissue from the same stem, taken from a layer of heart-wood, 24 years old: 6, ducts : a, portion of one of the minuter medullary rays. 199. Combined cross and longitudinal section of the same : a, tissue of a medullary ray. 11* 126 THE STEM. before ceased to take part in any vital operations. The cells of the older layers, also, commonly have thicker walls and smaller calibre than those of the newer, — as here shown in Fig. 198, 199, compared with Fig. 196, 197, — owing to the greater amount of thickening or- ganic materials (43) mingled with encrusting mineral matters intro- duced with the water imbibed by the roots (93) which have been de- posited upon them from within. This older, more solidified, and harder wood, which occupies the centre of the trunk, and is the part princi- pally valuable for timber, &c, is called Heart- wood, or Duramen : while the newer layers of softer, more open, and bibulous wood, more or less charged with sap, receive the name of Sap-wood, or Albur- num. The latter name was given by the earlier physiologists in allu- sion to its white or pale color. In all trees which have the distinction between the sap-wood and heart-wood well marked, the latter acquires a deeper color, and that peculiar to the species, such as the dark brown of the Black Walnut, the blacker color of the Ebony, the purplish-red of Red Cedar, and the bright yellow of the Barberry. These colors are owing to special vegetable products mixed with the incrusting matters ; but sometimes the hue appers to be rather an alteration of the lignine with age. In the Red Cedar, the deep color belongs chiefly to the medullary rays. In many of the softer Avoods, there is little thickening of the cell-walls, and little change in color of the heart-wood, except from incipient decay, as in the White Pine, Pop- lar, Tulip-tree, &c. The heart-wood is no longer in any sense a living part ; it may perish, as it frequently does, without affecting the life or health of the tree. 225. The Bark is much more various in structure and growth than the wood : it is also subject to grave alterations with advancing age, on account of its external position, viz. to distention from the con- stantly increasing diameter of the stem within, and to abrasion and decay from the influence of the elements without. It is never entire, therefore, on the trunks of large trees ; but the dead exterior parts, no longer able to enlarge with the enlarging Avood, are gradually fissured and torn, and crack off in layers, or fall away by slow decay. So that the bark of old trunks bears but a small proportion in thick- ness to the wood, even when it makes an equal amount of annual growth. 226. The three parts of the bark (214-217), for the most part readily distinguishable in the bark of young shoots, grow indepen- dently, each by the addition of new cells to its inner face, so long as THE BARK. 127 it grows at all. The green layer does not increase at all after the first year ; the opaque corky layer soon excludes it from the light ; and it gradually perishes, never to be renewed. The corky layer commonly increases for a few years only, by the formation of new tabular cells : occasionally it takes a remarkable development, form- ing the substance called Cork, as in the Cork Oak. A similar growth occurs on the bark of several species of Elm, of our Liquid- t____j < g^ i^ Z^ ^llS . gUfp amoai 01 oweei v*uni, occ., pro b ^^^^ ^gg^^^ @^@_ ducing thick corky plates on the ° §S§ ^§^i^§^ss£iEE% §1§ branches. In the White and Pa- b ®s eB®©fg»®®© sc-^h %. per Lirai, thin layers, of a very durable nature, are formed for a great number of years ; each layer of tabular and firmly cohe- rent cells (I lg. 200, a) alternates (Sias^a^'SSi with a thinner stratum of delicate, 200 somewhat cubical and less compact cells (b), which break up into a fine powder when disturbed, mad allow the thin, paper-like plates to exfoliate. 227. The liber, or inner bark (215), continues to grow through- out the life of the tree, by an annual addition from the cambium- layer applied to its inner surface. Sometimes the growth is plainly distinguishable into layers, corresponding with or more numerous than the annual layers of the wood : often, there is scarcely any trace of such layers to be discerned. In composition and appearance the liber varies greatly in different plants,* especially in trees and shrubs. That of Bass-wood or Linden, and of other plants with a similar fibrous bark, may be taken as best representing the liber. Here it consists of strata of very thick-walled cells alternating with thin-walled cells. The thick-walled cells are bast-cells (55, Fig. 49, 53), are much elongated vertically, and form the fibrous portion of * The best account of the liber that has yet been given is that by Mohl, in the Botanische Zeitung , Vol. 13, p. 873 (1855), of which a French translation is published in the Annates des Sciences Naturelles, ser. 4, Vol. 5, p. 141, et seq. (1856). FIG. 200. Transverse section of a minute portion of White Birch bark, the corky layer highly magnified : a, the firm, tabular cells, b, delicate thin-walled cells which separate the papery plates. (After Link.) 128 the stem:. the bark. The thin-walled cells are those of ordinary parenchyma, mingled, at the inner part of each stratum, with larger and longer ones, marked (on some sides at least) with the thin and reticulated spots or punctuations already described (215). These last may be termed the proper cells of the liber, as they are peculiar to this part of the bark, are seldom if ever absent, they contain an abundance of mucilage and proteine, and in all probability they take the principal part in the descending circulation of the plant, if it may so be called, i. e. in conveying downwards and distributing the rich sap which has been elaborated in the foliage. It is evident that the bast-cells, which in Linden (Fig. 53) are seen to be almost solid, are not adapted to this purpose. 228. That bast-cells are not an essential part, is further evident from the fact, that they are altogether wanting in the bark of some plants, and are not produced after the first year in many others. The latter is the case in Negundo, where abundant bast-cells, like those of Bass-wood, compose the exterior portion of the first year's liber (Fig. 194, 195, b), but none whatever is formed in the subsequent layers. In Beeches and Birches, also, a few bast-cells are produced the first year, but none afterwards. In Maples a few are formed in succeeding years. In the Pear bast-cells are annually formed, but in very small quantity, compared with the parenchymatous part of the liber. In Pines, at least in White Pines, the bark is nearly as homogeneous as the wood, the whole liber, except what answers to the medullary rays, consisting of one kind of cells, resembling those of bast or of wood in form, but agree- ing with the proper liber-cells in their structure and markings. Although the liber of Birch produces no bast- cells after the first year, it abounds in short cells equally solidified by in- ternal deposition, and of a gritty tex- ture, which might be mistaken for 201 bast-cells on the cross-section (Fig. 201). A longitudinal section discloses the difference. 229. The bark on old stems is constantly decaying or falling away from the surface, Avithout any injury to the tree ; just as the heart- wood may equally decay within without harm, except by mechani- FIG. 201. Cross-section of a cluster of solidified and indurated cells from the liber of the White Birch. (After Link.) THE LIVING PARTS OF A TREE. 129 cally impairing the strength of the trunk. Great differences are observable as to the time and manner in which the older bark of different shrubs and trees is thrown off, according to the struc- ture in each species. Some trees and shrubs have their trunks in- vested with the liber of many years' growth, although only the in- nermost layers are alive ; in others it scales off much earlier. On the stems of the common Honeysuckle, of the Nine-Bark (Spiraea opulifolia), and of Grape-vines (except of our Muscadine Grape), the liber lives only one season, and is detached the following year, hanging loose in papery layers in the former species, and in fibrous shreds in the latter. 230. While the newer layers of the wood abound in crude sap, which they convey to the leaves (224), those of the inner bark abound in elaborated sap (79, 227), which they receive from the leaves and convey to the cambium-layer or zone of growth. The proper juices and peculiar products of plants (88) are accordingly found in the foliage and the bark, especially in the latter. In the bark, therefore, (either of the stem or of the root,) medicinal and other principles are usually to be sought, rather than in the wood. Nevertheless, as the wood is kept in connection with the bark by the medullary rays, many products which probably originate in the former are deposited in the wood. 231. The living Parts of a Tree or Shrub, of the Exogenous kind, are obviously only these: — 1st. The summit of the stem and branches, with the buds which continue them upwards and annually develop the foliage. 2d. The fresh tips of the roots and rootlets annually developed at the opposite extremity. 3d. The newest strata of wood and bark, and especially the interposed cambium-layer, which, annu- ally renewed, maintain a living communication between the rootlets on the one hand and the buds and foliage on the other, however dis- tant they at length may be. These are all that is concerned in the life and growth of the tree ; and these are annually renewed. The branches of each year's growth are, therefore, kept in fresh commu- nication, by means of the newer layers of wood, with the fresh rootlets, which are alone active in absorbing the crude food of the plant from the soil. The fluid they absorb is thus conveyed directly to the branches of the season, which alone develop leaves to digest it. And the sap they receive, having been elaborated and converted into organic nourishing matter, is partly expended in the upward growth of new branches, and partly in the formation of a new layer 130 THE STEM. of wood, reaching from the highest leaves to the remotest rootlets.* As the exogenous tree, therefore, annually renews its buds and * The layers of wood and bark, by which the exogenous stem annually in- creases in diameter, are formed by the multiplication of the cells of the cambium- layer throughout its whole extent. That the organic material to supply this growth in ordinary vegetation descends in the bark, for the most part, and that the order of growth in the formation of wood is from above downwards, and also the general dependence of this growth upon the action of the foliage, may be inferred from a variety of facts and considerations. The connection of the wood with the leaves is shown: — (1.) By tracing the threads of soft woody Endogens, such as Yucca, directly from the base of the leaf into the stem, and thence downward to their termination, towards which they become attenuated, lose their vessels, and are finally reduced to slender shreds of woody tissue. (2.) The amount of wood formed in a stem or branch, other things being equal, is in a relation to the number and size of the leaves it bears ; its amount in any portion of the branch is in direct proportion to the number of leaves above that portion. Thus, when the leaves are distributed along a branch, it tapers to the 6ummit, as in a common Reed or a stalk of Indian Corn ; when they grow in a cluster at the apex, it remains cylindrical, as in a Palm (Fig. 184). Consequently the increase of the trunk in diameter directly corresponds with the number and vigor of the branches. The greater the development of vigorous branches on a particular side of a tree, the more wood is formed, and the greater the thickness of the annual layers on that side of the trunk. (3.) In a seedling, the wood appears in proportion as the leaves are developed. (4.) If a young branch be cut off just below a node (156), so as to leave an internode without leaves or bud, little or no increase in diameter will ordinarily take place down to the first leaf below. But if a bud be inserted into this naked internode, as the bud de- velops, increase in diameter, with the formation of new wood, recommences. That the formation proceeds from above downwards, or that the elaborated sap which furnishes the material for the growth is diffused from above downwards, appears from the effect of a ligature around exogenous stems, or of removing a ring of bark. It is a familiar fact, that, when a ligature is closely bound around a growing exogenous stem, the part above the ligature swells, and that below docs not. Every one may have observed the distortions that twining stems thus accidentally produce upon woody exogenous trunks, causing an enlargement on the upper side of the obstruction. When the stem is girdled, by removing a ring of bark so as completely to expose the surface of the wood, the part above the ring enlarges in the same manner ; that below does not, until the incision is healed. The wood of the roots is manifestly formed in a descending direction. But this is continuous with that of the stem; and its first layer, the extension of the wood of the radicle into the primary root, agrees in composition with the wood of the succeeding layers in the stem, having no spiral vessels, but only ducts. Still, whatever analogy there may be between the growth of the wood in the stem and of roots, there is no real basis for the ingenious conception of Thouars and of Gaudichaud, that wood is the roots of buds or leaves, or that it is absolutely dependent upon them for its formation. COMPOSITE NATURE OF A PLANT. 131 leaves, its wood, bark, and roots, — evei'ything, indeed, that is con- cerned in its life and groAvth, — there seems to be no reason, no necessary cause inherent in the tree itself, why it may not live in- definitely. Accordingly, some trees are known to have lived for twelve hundred years or more ; and others now survive which are probably above two thousand years old, and perhaps much older.* This longevity ceases to be at all surprising when we consider, that, although the tree or herb is in a certain sense an individual, yet it is not an individual in the sense that a man or any ordinary animal is. Viewed philosophically, 232. The Plant is a Composite Being, or community, lasting, in the case of a tree especially, through an indefinite and often immense number of generations. These are successively produced, enjoy a term of existence, and perish in their turn. Life passes onward continually from the older to the newer parts, and death follows, with equal step, at a narrow interval. No portion of the tree is now living that was alive a few years ago ; the leaves die annually and are cast off, while the internodes or joints of stem that bore them, as to their wood at least, buried deep in the trunk, under the wood of succeeding generations, are converted into lifeless heart-wood, or perchance decayed, while the bark that belonged to them is thrown off from the surface. It is the aggregate, the blended mass alone, that long survives. Plants of single cells, and of a definite form, alone exhibit complete individuality ; and their existence is ex- tremely brief. The more complex vegetable of a higher grade is not to be compared with the animal of the highest organization, where the offspring always separates from the parent, and the indi- vidual is simple and indivisible. But it is truly similar to the branch- ing or arborescent coral, or to other compound animals of the lowest grade, where successive generations, though capable of living inde- pendently and sometimes separating spontaneously, yet are usually developed in connection, blended in a general body, and nourished more or less in common. Thus the coral structure is built up by the combined labors of a vast number of individuals, — by the suc- * The subject of the longevity of trees has been ably discussed by De Can- dolle, in the Bibliotheque Universelle of Geneva, for May, 1831, and in the second volume of his Plujsiologie Vegetale : also, more recently, by Professor Alphonso De Candollc. In this country, an article on the subject has appeared in the North American Review, for July, 1 844. 132 THE STEM. cesslve labors of a great number of generations. The surface or the recent shoots alone are alive ; and here life is superficial, all under- neath consisting of the dead remains of former generations. The arborescent species are not only lifeless along the central axis, but are dead throughout towards the bottom : as, in a genealogical tree, only the later ramifications are among the living. It is the same with the vegetable, except that, as it ordinarily imbibes its nourish- ment mainly from the soil through its roots, it makes a downward growth also, and, by constant renewal of fresh tissues, maintains the communication between the two growing extremities, the buds and the rootlets. 233. Individuality being imperfectly realized in the vegetable kingdom, the question as to what in the Phamogamous plant best answers to the animal individual is speculative, rather than practical, and may be more appropi'iately noticed in another place. (Part II. Chap. I.) 234. Comparison of Endogenous with Exogenous Structure. The woody bundles of an exogenous stem (Fig. 186-188) continue to grow on the outer side as long as the plant lives. In woody trunks they at once become wedges with the point next the pith, and growth pro- ceeds indefinitely by the stratum of perpetually renewed tissue on the outer face between the wood and the bark. Each wedge is separated from its neighbor on both sides by an interposed medul- lary ray, and is composed of wood on the inner side, liber on the outer, and cambium or forming tissue between. Now each thread or bundle of endogenous wood (204) is composed of similar or anal- ogous parts, sometimes irregularly intermixed, but more commonly similarly disposed. That is, the section of one of these threads ex- hibits woody tissue and one or two spiral vessels on its inner border, answering to the proper wood, and very thick-walled elongated cells on its outer border, of the same nature as the bast-cells of Exogens ; and between the two is a stratum of cells of parenchyma mixed with elongated and punctuated cells answering to the proper cells of the inner part of the liber. The portion of each endogenous thread, therefore, which looks towards the centre of the trunk, answers to the wood, and its outer portion to the liber or inner bark, of the ex- ogenous stem ; and the parenchyma through which the threads are interspersed answers to the medullary rays and pith together. The main difference between the endogenous woody threads and the ex- ogenous woody wedges is, that there is no cambium-layer in the THE LEAVES. 133 former between the liber and the wood, and therefore no provision for increase in diameter. The bundles are therefore strictly limited, while tbose of Exogens are unlimited in growth. In Exogens the woody bundles or wedges, symmetrically arranged in a circle, be- come confluent into a zone in all woody and most herbaceous stems, which continues to increase in thickness. In Endogens the woody bundles are unchanged in size after their formation, but new and distinct ones are formed in the growing stem with each leaf it de- velops, and interspersed more or less irregularly among the older bundles. CHAPTER V. OF THE LEAVES. Sect. I. TriEiR Arrangement. (Phyllotaxis, etc.) 235. TriE situation of leaves, as well as their general office in the vegetable economy, and several of their special adaptations, has already been stated. Leaves invariably arise from the nodes (156), just below the point where buds appear. So that wherever a bud or branch is found, a leaf exists, or has existed, either in a perfect or rudimentary state, just beneath it ; and buds (and therefore branch- es), on the other hand, are or may be developed in the axils of all leaves, and do not normally exist in any other situation. The point of attachment of a leaf (or other organ) with the stem is termed its insertion. The subject of the arrangement of leaves on the stem has received the name of 236. Phyllotaxis (from two Greek words, signifying leaf-arrange- ment). 237. As to their general position, leaves are either alternate, oppo- site, or verticillate. They are said to be alternate (127, and Fig. 121, 157, 204) when there is only one to each node, in which case the successive leaves are thrown alternately to different sides of the stem. They are said to be opposite when each node bears a pair of leaves, in which case the two leaves always diverge from each other as widely as possible, that is, they stand on opposite 12 134 THE LEAVES. sides of the stem and point in opposite directions (127, Fig. 107, 210, &c). They are verticillate, or wJwrled, when there are three or more leaves in a circle (verticil or whorl) upon each node ; in which case the several leaves of the circle diverge from each other as much as possible, or are equably distributed around the whole circumfer- ence of the axis (Fig. 134, 211). The first of the three is the simplest as well as the commonest method, occurring as it does in almost every Monocotyledonous plant (where it is plainly the normal mode, 128), and in the larger number of Dicotyledonous plants likewise, after the first or second nodes (Fig. Ill*, 121). It should therefore be first examined. 20O 238. Alternate leaves. This general term for the case where leaves are placed one after another, obviously comprises a variety of modes as to the particular position of succes- sive leaA'es. There is, first, the case to which the name is most applicable, viz. where the leaves are alternately disposed on exactly op- posite sides of the stem (as in Fig. 157) ; the second leaf being on the side farthest from the first, while the third is equally distant from the second, and is consequently placed directly over the first, the fourth stands over the second, and so on throughout. Such leaves are accordingly distichous or two-ranked,* They form two vertical rows : on one side are the 1st, 3d, 5th, 7th, &c. ; on the op- posite side are the 2d, 4th, 6th, 8th, and so on. This mode occurs in all Grasses, in many other Monocotyledonous plants, and among the Dicotyledonous in the Linden. A second mode is 239. The tristichous or three-ranked ar- rangement, which is seen in Sedges (Fig. * In the course of the summer the leaves of Baptisia perfoliata, which are really five-ranked, often appear to be monostichous, or one-ranked; but this is owing to a torsion of the axis. FIG. 202. Tiece of a stalk, with the sheathing bases of the leaves, of a Sedge-Grass (Carex Crus-corvi), showing the three-ranked arrangement. 203. Diagram of the cross-section of the same, showing two cycles of leaves. THEIR ARRANGEMENT. 135 202) and some other Monocotyledonous plants. Taking any leaf we please to begin with, and numbering it 1, we pass round one third of the circumference of the stem as we ascend to leaf No. 2 ; another third of the circumference brings us to No. 3 ; another brings us round to a point exactly over No 1, and here No. 4 is placed. No. 5 is in like manner over No. 2, and so on. They stand, therefore, in three vertical rows, one of which contains the numbers 1, 4, 7, 10 ; another, 2, 5, 8, 11 ; the third, 3, 6, 9, 12, and so on. If we draw a line from the insertion of one leaf to that of the next, and so on to the third, fourth, and the rest in succession, it will be perceived that it winds around the stem spirally as it ascends. In the first or dis- tichous mode, the second leaf is separated from the preceding by half the circumference of the stem ; and, having completed one turn round the stem, the third begins a second turn. In the tristichous, each leaf is separated from the preceding and succeeding by one third of the circumference, there are three leaves in one turn, or cycle, and the fourth commences a second cycle, which goes on in the same way. That is, the angular divergence, or arc interposed between the insertion of two successive leaves, in the first is J, in the second •£, of the circle. These fractions severally represent, not only the angle of divergence, but the whole plan of these two modes ; the numerator denoting the number of times the spiral line winds round the stem before it brings a leaf directly over the one it began with ; while the denominator expresses the number of leaves that are laid down in this course, or which form each cycle. The two- ranked mode (J-) is evidently the simplest possible case. The tlu-ee- ranked (J) is the next, and the one in which the spiral character of the arrangement begins to be evident. To this succeeds 240. The pentastichous, quincuncial, or Jive-ranked arrangement (Fig. 204, 205). This is much the most common case in alternate- leaved Dicotyledonous plants. 'The Apple, Cherry, and Poplar afford ready examples of it. Here there are five leaves in each cycle, since Ave must pass on to the sixth before we find one placed vertically over the first. To reach this, the ascending spiral line has made two revolutions round the stem, and on it the five leaves are equably distributed, at intervals of f of the circumference. The fraction § accordingly expresses the angular divergence of the suc- cessive leaves ; the numerator indicates the number of turns made in completing the cycle, and the denominator gives the number of leaves in the cycle, or the number of vertical ranks of leaves on such 136 THE LEAVES. a stem. If we shorten the axis, as it was in the hud, or make a 204 horizontal plan, we have the parts disposed as in the diagram, Fig. 206, the low- er leaves heing of course the exterior. 241. The eight-ranked arrangement, the next in order, is likewise not un- common. It is found in the Holly, the Callistemon of our conservatories, the Aconite, the tuft of leaves at the base of the common Plantain, &c. In this case the ninth leaf is placed over the first, the tenth over the second, and so on ; and the spiral line makes three turns in laying down the cycle of eight leaves, each separated from the preceding by an arc, or an- gular divergence, of f of the circumference. 242. All these modes, or nearly all of them, 206 were pointed out by Bonnet as long ago as the middle of the last century ; but they have recently been extended and generalized, and the mutual relations of the various methods brought to light, by Schimper, Braun, and others. If we write down in order the series of fractions which represent the simpler forms of phyllotaxis already noticed, as determined by observation, viz. £, -1, § , § , we can hardly fail to perceive the relation that they bear to each other. For the numerator of each is composed of the sum of the numerators of the two preceding fractions, and the denominator of the sum of the two preceding denominators. Also the numerator of each fraction is the denominator of the next but one preceding. Extending this series, we obtain the further terms, T 5 g-, ? 8 T , ^f , § i, &c. Now these numbers are verified by observation, and, with some abnormal excep- tions, this series A, 1, §, •§, T 5 ffJ ? 8 T , i|, f 1 comprises all the varia- FIG. 204. A branch exhibiting the five-ranked arrangement of leaves. FIG. 205. Diagram of the same : a spiral line is drawn ascending the stem and passing through the successive scars which mark the position of the leaves from 1 to G. It is made a dotted line where it passes on the opposite side of the stem, and the scars 2 and 5, which fall on that side, are made fainter. 206. A plane, horizontal projection of the same ; the dotted line passing from the edge of the first leaf to the second, and so on to the fifth leaf, which completes the cycle ; as the sixth would come directly before, or within, the first. THEIR ARRANGEMENT. 137 tions of the - arrangement of alternate leaves that actually occur. These higher forms are the most common Avhere the leaves are crowded on the stem, as in the rosettes of the Houseleek (Fig. 207), and the scales of the Pine-cones (for the ar- rangement extends to all parts that are modifi- cations of leaves), or where they are numerous and small in proportion to the circumference of the stem, as the leaves of Firs, &c. In fact, when the internodes are long and the base of the leaves large in proportion to the size of the stem, it is difficult, and often impossible, to tell whether the 9th, 14th, or 22d leaf stands ex- actly over the first. And when the internodes are very short, so that the leaves touch one another, or nearly so, we may readily per- ceive what leaves are superposed ; but it is then difficult to follow the succession of the intermediate leaves. The order, however, may be deduced by simple processes. 243. Sometimes we can readily count the number of vertical ranks, which gives the denominator of the fraction sought. Thus, if there are eight, Ave refer the case to the f arrangement in the regu- lar series ; if there are thirteen, to the -jAj arrangement, and so on. Commonly, however, when the leaves are crowded, the vertical ranks are by no means so manifest as two or more orders of oblique series, or secondary spirals, which are at once seen to wind round the axis in opposite directions, as in the Houseleek (Fig. 207 ; where the number's, 1, 6, 11 belong to a spire that winds to the left; 1, 9, 17 to another, which winds to the right; and 3, G, 9, 12 to still another, that winds in the same direction) : they are still more ob- vious in Pine-cones (Fig. 208, 209). These oblique spiral ranks are a necessary consequence of the regular ascending arrangement of parts with equal intervals over the circumference of the axis : and if the leaves are numbered consecutively, these numbers will neces- sarily stand in arithmetical progression on the oblique ranks, and have certain obvious relations with the primary spiral which origi- nates them ; as will be seen by projecting them on a vertical plane. 244. Take, for example, the quincunical (f ) arrangement, where, as in the annexed diagram, the ascending spiral, as written on a plane surface, appears in the numbers 1, 2, 3, 4, 5, 6, and so on: FIG. 207. An offset of the Houseleek, with the rosette of leaves unexpanded, exhibiting the 5-13 arrangement ; the fourteenth leaf beiDg directly over the first. 12* 138 THE LKAVES. the vertical ranks thus formed, beginning with the lowest (which we place in the middle column, that it may correspond with the Larch-cone, Fig. 208, where the lowest scale, 1, is turned directly towards the observer), are neces- sarily the numbers 1, 6, 11 ; 4, 9, 14 ; 2, 7, 12 ; 5, 10, 15 ; and 3, 8, 13. But two parallel oblique ranks are equally apparent, ascending to the left ; viz. 1, 3, 5, which, if we coil the diagram round a cylinder, will be continued into 7, 9, 11, 13, 15 ; and also 2, 4, G, 8, 10, which runs into 12, 14, and so on, if the axis be further prolonged. Here the circumference is occupied by two secondary left-hand series, and Ave notice that the common difference in the sequence of numbers is two : that is, the number of the parallel sec- ondary spirals is the same as the common difference of the numbers on the leaves that compose them. Again, there are other parallel secondary spiral ranks, three in number, which ascend to the right ; viz. 1, 4, 7, continued into 10, 13 ; 3, 6, 9, 12, continued into 15 ; and 5, 8, 11, 14, &c. ; where again the common difference, 3, accords with the number of such ranks. This fixed relation enables us to lay down the proper numbers on the leaves, when too crowded for directly following their succession, and thus to ascertain the order of the primary spiral series by noticing what numbers come to be super- posed in the vertical ranks. AVe take, for example, the very simple cone of the small-fruited American Larch (Fig. 208), which usually completes only two cycles ; for we see that the lowest, one interme- diate, and the highest scale, on the side towards the observer, stand in a vertical row. Marking this lowest scale 1, and counting the parallel secondary spirals that wind to the left, we find that two occupy the whole circumference. From 1, we number on the scales of that spiral 3, 5, 7, and so on, adding the common difference 2, at each step. Again, counting from the base the right-hand secondary spirals, we find three of them, and therefore proceed to number the lowest one by adding this common difference, viz. 1,4,7, 10; then, pass- ing to the next, on which the No. 3 has already been fixed, we carry on that sequence, 6, 9, &c. ; and on the third, Avhere No. 5 is already fixed, Ave continue the numbering, 8, 11, &c. This gives us, in the A'ertical rank to which No. 1 belongs, the sequence 1, 6, 11, shoAving FIG. 208. A cone of the small-fruited American Larch (Larix Americana), with the scales numbered, exhibiting the five-ranked arrangement, as in the annexed diagram. THEIR ARRANGEMENT. 139 that the arrangement is of the quincuncial (f ) order. It is further noticeable, that the smaller number of parallel secondary spirals, 2, agrees with the numerator of the fraction in this the § arrangement ; and that this number added to that of the parallel secondary spirals which wind in the opposite direction, viz. 3, gives the denominator of the fraction. This holds good throughout ; so that we have only to count the number of parallel secondary spirals in the two direc- tions, and assume the smaller number as the numerator, and the sum Vertical Projection Vertical Projection of the -^ of the -| Arrange- Arrangement, ment. 27 26 2.3 21 23 22 19 21 20 IS 16 11 13 12 11 2.:, 24 28 22 21 20 19 IS 17 16 IS 14 10 ± of this and the larger number as the denominator, of the fraction which expresses the angular divergence sought. For this we must FIG 209. A cone of the White Pine, on which the numbers are laid down, and the leading higher secondary spirals are indicated : those with the common difference 8 are marked by dotted lines ascending to the right ; two of the five that wind in the opposite direction are also marked with dotted lines : the set with the common difference 3, in one direction, and that with the common difference 2, in the other, are very manifest in the cone. 140 THE LEAVES. take, however, the order of secondary spirals nearest the vertical rank in each direction, when there are more than two, as there are in all the succeeding cases. 245. A similar diagram of the f arrangement introduces a set of secondary spirals, in addition to the two foregoing, ascending in a near- er approach to a vertical line, and with a higher common difference, viz. 5. There are accordingly five of this sort, viz. those indicated in the diagram by the series 1, 6, 11, 16 ; 4, 9, 14, 19, 24 ; 2, 7, 12, 17, 22 ; 5, 10, 15, 20, 25 ; and 3, 8, 13, 18, 23. The highest obvious spiral in the opposite direction, viz. that of which the series 1, 4, 7, 10, 13 is a specimen, has the common difference 3, and gives the numerator, and 3 -\- 5 the denominator, of the fraction f . The next case, T 5 3 , which is exemplified in the rosettes of the Houseleek (Fig. 207) and in the cone of the White Pine (Fig. 209), introduces a fourth set of secondary spirals, eight in number, with the common difference eight, viz. that of which the series 1, 9, 17, 25 is a repre- sentative. The set that answers to this in the opposite direction, viz. 1, 6, 11, 16, 21, 26, with the common difference 5, gives the numerator, and 5 -J- 8 the denominator, of the fraction T 5 ^. We may here compare the diagram with an actual example (Fig. 209) : a part of the numbers are of course out of sight on the other side of the cone. The same laws equally apply to the still higher modes. 246. The order is uniform in the same species, but often various in allied species. Thus, it is only § in our common American Larch ; in the European species, ^ T . The White Pine is -f^, as is also the Black Spruce ; but other Pines with thicker cones exhibit in differ- ent species the fractions ^ 8 T , -££ , and f|. Sometimes the primitive spiral ascends from left to right, sometimes from right to left. One direction or the other generally prevails in each species, yet both directions are not unfrequently met with, even in different cones of the same tree. 247. When a branch springs from a stem or parent axis, the spi- ral is continued from the leaves of the stem to those of the branch, so that the leaf from Avhose axil the branch arises begins the spire of that branch. When the spire of the branch turns in the same direction as that of the parent axis, as it more commonly does, it is said to be homodromous (from two Greek words, signifying like course) : when it turns in the opposite direction, it is said to be heterodromous (or of different course). 248. The cases represented by the fractions £, ■£, and § are the THEIK ARRANGEMENT, 141 most stable and certain, as well as the easiest to observe. In the higher forms, the exact order of superposition often becomes uncer- tain, owing to a slight torsion of the axis, or to the difficulty of observing whether the 9th, 14th, 22d, 35th, or 56th leaf is truly over the first, or a little to the one side or the other of the vertical line. Indeed, if we express the angle of divergence in degrees and minutes, we perceive that the difference is so small a part of the circumference, that a very slight change will substitute one order for another. The divergence in T 5 7 = 138° 24'. In all those beyond, it is 137° plus a variable number of minutes, which approaches nearer and nearer to 30'. Hence M. Bravais considers all these as mere alterations of one typical arrangement, namely, with the angle of divergence 137° 30' 28", which is irrational to the circumference, that is, not capable of dividing it an exact number of times, and con- sequently never bringing any leaf precisely in a right line over any preceding leaf, but placing the leaves of what Ave take for vertical ranks alternately on both sides of this line and very near it, approach- ing it more and more, without ever exactly reaching it. These forms of arrangement he therefore distinguishes as curvt'sen'al, be- cause the leaves are thus disposed on an infinite curve, and are never brought into exactly straight ranks. The others are correspondingly termed rectiserial, because, as the divergence is an integral part of the circumference, the leaves are necessarily brought into rectilineal ranks for the whole length of the stem. 249. A different series of spirals sometimes occurs in alternate leaves, viz. £, \, f , T 3 f ; and still others have been detected; but these are rare or exceptional cases. 250. Opposite Leaves (237, Fig. 210). In these, almost without exception, the second pair is placed over the intervals of the first, the third over the intervals of the second, and so on. More commonly, as in plants of the Labiate or Mint Family, the successive pairs cross each other exactly at right angles, so that the third pair stands directly over the first, the fourth 210 over the second, &c, forming four equidistant vertical ranks for the FIG. 210. Opposite leaves of the Strawberry-bush, or Euonymus Americanus. 142 THE LEAVES. whole length of the stem. In this case, the leaves are said to he decussate. In other cases, as in the Pink Family, often the succes- sive pairs deviate a little from this line, so that we have to pass several pairs before we reach one exactly superposed over the pair we start with. This indicates a spiral ar- rangement, which falls into some one of the modes already illustrated in alternate leaves* only that here each node bears a pair of leaves. 251. Verticillate or Whorled leaves (Fig. 211) follow the same modes of arrangement as op- posite leaves. Sometimes they decussate, or the leaves of one whorl correspond to the intervals of that underneath, making twice as many vertical ranks as there are leaves in the whorl ; sometimes they wind spirally, so that each leaf of the whorl belongs to as many parallel spirals, analogous to the secondary spirals in the case of alternate leaves. 252. The opposition or alternation of the leaves is generally constant in the same species, and often through the same family ; yet both modes occasionally occur on the same stem, as in the common Snap- dragon and the Myrtle. All Exogens, having their cotyledons opposite, necessarily commence with that mode (Fig. 103-125); many retain it throughout ; others change to alternation, either directly in the primordial leaves (Fig. 111°, 121), or at a later period. In Endogens, on the contrary, the first leaves are necessarily alternate (128), and it is seldom that they afterwards exhibit opposite or whorled leaves. The Pine in germination commences with a whorl of leaves (Fig. 133, 134) ; but the subsequent ones are alternate. The Pine, however (Fig. 212), and the Larch, bear what are termed 2I2 253. Fascicled Leaves. These are really the leaves of an axil- lary bud. They remain in a tuft or cluster because the axis of FIG. 211. Verticillate or whorled leaves of a Galium or Bedstraw. FIG. 212. Piece of a branchlet of Pitch Pine, with three leaves in a fascicle or bundle, in the axil of a thin scale (a) which answers to a primary leaf. The bundle is surrounded at the base by a short sheath, formed of the delicate scales of the axillary bud. VERNATION OR PR.EFOLIATION. 143 the bud does not lengthen. This is plainly seen in the spring leaves of the Barberry and of the Larch (Fig. 213), crowded on short spurs, some of which soon elongate into ordinary shoots with scattered alternate leaves. Their nature is less evident in Pines, on account of the peculiar character of the leaves of the main axis, from whose axil the tuft of two, three, or five leaves arises, the primary leaf in this case being a thin and chaffy scale (Fig. 212, a) which soon falls off, while the actual foliage all be- longs to the axillary clusters. So in the common Barberry the prop- er leaves of the lengthened stems are chiefly in the form of spines (Fig. 29G), and the actual foliage appears in fascicles in their axils. 254. As regards their general position on the stem, leaves are said to be radical, when they are borne on the stem at or below the sur- face of the ground, so as apparently to grow from the root, as those of the Bloodroot, Plantain, Primrose, and of the acaulescent (154) Violets : those that arise along the main stem are termed cauline ; those of the branches, rameal ; and those which stand upon or at the base of flower-branches are called floral ; the latter, moreover, are generally termed bracts. 255. With respect to succession, those leaves which manifestly exist in the embryo are called seminal ; the first or original pair receiving the name of cotyledons (120), and usually differing wide- ly in appearance from the ordinary leaves which succeed them. The earliest ordinary leaves are termed primordial. These, as well as the cotyledons, usually perish soon after others are developed to supply their place. 256. As pertaining to the arrangement of leaves, we should here notice the modes in which they are disposed before expansion in the bud ; namely, their 257. Vernation Or Pracfoliatioil. The latter is the most character- istic name, but the former, given by Linnosus (literally denoting their spring state), is the more ancient and usual. Two tilings are included under this head : — 1st, the mode in which each leaf con- sidered separately is disposed ; 2d, the arrangement of the several FIG. 213. Piece of a branchlet of the Larch, with two fascicles of leaves. 144 THE LEAVES. leaves of the same bud in respect to each other. This last is evi- dently connected with phyllotaxis, or their position and order of succession on the stem. As to the first, leaves are for the most part either lent or folded, or rolled up in vernation. Thus, the upper part may be bent on the lower, so that the apex of the leaf is brought down towards the base, as in the Tulip-tree, when the leaves are inflexed or reclinate in vernation ; or the leaf may be folded along its midrib or axis, so that the right half and the left half are applied together, as in the Oak and the Magnolia, when the leaves are conduplicate ; or each leaf may be folded up a cer- tain number of times like a fan, as in the Maple, Currant, and Vine, when they are said to be plicate or plaited. The leaf may be rolled either parallel with its axis, or on its axis. In the latter case it is spirally rolled up from the apex towards the base, like a crosier, or circinnate, as in true Ferns (Fig. 100), and among Phamoga- mous plants in the Drosera or Sundew. Of the former there are three ways ; viz. the whole leaf may be laterally rolled up from one edge into a coil, with the other edge exterior, when the leaves are said to be convolute, as in the Apricot and Cherry ; or both edges may be equally rolled towards the midrib ; either inwards, when they are involute, as in the Violet and the "Water-Lily ; or else out- wards, when they are revolute, as in the Eosemary and Azalea. Fig. 214-219 are Linnasan diagrams of sections of leaves, illustrating the principal modes of vernation. 258. Considered relatively to each other, leaves are valvate in vernation when corresponding ones touch each other by their edges 214 215 2i6 only, Avithout overlap- s^. ft A ^- — ^ phig: they are imbri- /f^ \ *9 /T\\ cated when the outer C&? ^l/LSN* \w^-*^/ successively overlap the inner, by then- edges at least, in which case the order of over- lapping exhibits the phyllotaxis, or order of succession and po- sition. In these cases the leaves are plane or convex, or at least not much bent or rolled. FIG. 214. Conduplicate ; 215. Plicate or plaited ; 216. Convolute ; 217. Revolute ; 218. Involute ; and, 219. Circmate, vernation. THEIR STRUCTURE AND CONFORMATION. 145 When leaves with their margins involute are applied together in a circle without overlapping, the vernation is induplicate. When, in conduplicate leaves, the outer successively embrace or sit astride of those next within, the vernation is equitant, as the leaves of the Iris at their base (Fig. 296) ; or when each receives in its fold the half of a corresponding leaf folded in the same manner, the vernation is half-equitant or obvolute. These terms equally apply to leaves in their full-grown condition, whenever they are then so situated as to overlie or embrace one another. They likewise apply to the parts in the flower-bud, under the name of aestivation or prrefloration. Chap. IX. Sect. V. Sect. II. Their Structure and Conformation. 259. Anatomy Of the Leaf. The complete leaf consists of the Blade {Lamina or Limb, Fig. 229, b), with its Petiole or Leaf- stalk, p, and at its base a pair of Stipules, st. Of these the latter are frequently absent altogether, and in many cases where they originally exist they fall away as the leaf expands. The petiole is very often wanting ; when the leaf is sessile, or has its blade rest- ing immediately on the stem that bears it (as in Fig. 210, 211). Sometimes, moreover, there is no proper blade, but the whole organ is cylindrical or stalk-like. It is the general characteristic of the leaf, however, that it is an expanded body. Indeed, it may be viewed as a contrivance for increasing the green surface of a plant, so as to expose to the light and air the greatest practicable amount of paren- chyma containing the green matter of vegetation (chlorophyll, 92), upon which the light exerts its peculiar action. Leaves as foliage, accordingly, are what Ave are now principally to consider 260. In a general, mechanical way, it may be said leaves are defi- nite protrusions of the green layer of the bark, expanded horizon- tally into a thin lamina, and stiffened by tough, woody fibres (con- nected both with the liber, or inner bark, and the wood), which form its framework, ribs, or veins. Like the stem, therefore, the leaf is made up of two distinct parts, the cellular and the woody. The cellular portion is the green pulp or parenchyma : the woody, is the skeleton or framework which ramifies among and strengthens the former. The woody or fibrous portion fulfils the same purposes in the leaf as in the stem, not only giving firmness and support to the 13 146 THE LEAVES. delicate cellular apparatus, but also serving for the conveyance and distribution of the sap. The subdivision of these ribs, or veins, of the leaf, as they are not inappropriately cajled, continues beyond the limits of unassisted vision, until the bundles or threads of woody tissue are reduced to very delicate fibres, ramified throughout the green pulp. 261. The cellular portion of the leaf consists of thin-walled cells of loose parenchyma, containing grains of chlorophyll, to which the green color of foliage is entirely owing. The cells are not heaped promiscuously, but exhibit a regular arrangement ; upon a plan, too, which varies in different parts of the leaf, according to the different conditions in which it is placed. 262. Leaves are almost always expanded horizontally, so as to present one surface to the ground and the other to the sky ; and the parenchyma forms two general strata, one belonging to the upper and the other to the lower side. The microscope displays a manifest difference in the parenchyma of these two strata. That of the upper stratum is composed of one or more compact layers of oblong cells, placed endwise, or with their long diameter perpen- dicular to the surface ; while that of the lower stratum is very loosely arranged, leaving numerous vacant spaces between the cells ; and when the cells are oblong, their longer diameter is parallel with the epidermis. This is shown in Fig. 7, which represents a magnified section through the thickness (perpendicular to the surface) of a leaf of the Star-Anise of Florida ; where the upper stratum of parenchyma consists of only a single series of perpendicular cells. Also in Fig. 220, which represents a similar view of a thin slice of a leaf of the Gar- den Balsam. Fig. 221 repre- sents a piece cut out of a leaf of the White Lily ; where the upper stratum is composed of only one compact layer of ver- tical cells. The parenchyma is alone represented ; the woody por- tion, or veins, being left out. The more compact structure of the FIG. 220. magnified section through the thickness of a leaf of the Garden Balsam : a, sec- tion of the epidermis of the upper surface ; 6, of the upper stratum of parenchyma ; c, of the lower stratum ; d, of the epidermis of the lower surface. (After Brongniart.) THEIR ANATOMICAL STRUCTURE. 147 upper stratum shows why the upper surface of leaves is of a deeper green than the lower. 263. The object which this arrangement subserves will appear evident, when we consider that the spaces between the cells, filled with air, communicate freely with each other throughout the leaf, and also with the external air by means of openings in the epider- mis (presently to be described) ; and when Ave consider the powerful action of the sun to promote evaporation, especially in dry air ; and that the thin walls of the cells, like all vegetable membrane, allow of the free escape of the contained moistiu*e by transudation. The compactness of the cells of that stratum which is pi'esented immedi- ately to the sun, and their vertical elongation, so that each shall expose the least possible surface, obviously serve to protect the loose parenchyma beneath from the too powerful action of direct sunshine. This provision is the more complete in the case of plants which retain their foliage through a season of drought in arid re- gions, where the soil is usually so parched during the dry season, that, for a long period, it affords only a scanty supply of moisture to the roots. Compare, in this respect, a leaf of the Lily (Fig. 221), where the upper stratum contains but a single layer of barely oblong cells, with the firm and more enduring leaf of the Oleander, the upper stratum of which consists of two layers of long and narrow vertical cells as closely compacted as possible (Fig. 222). So dif- FIG. 221. A magnified section through the thickness of a minute piece of the leaf of the White Lily of the gardens, showing also a portion of the under side with some breathing-pores. 148 THE LEAVES. ferent is the organization of the two strata, that a leaf soon perishes if reversed so as to expose the lower surface to direct sunshine. 264. A further and more effectual provision for restraining the perspiration of leaves within due limits is found in the Epidermis, or skin, that invests the leaf, as it does the whole surface of the vege- table (69), and which is so readily detached from the succulent leaves of such plants as the Stonecrop and the Live-for-ever (Sedum) of the gardens. The epidermis is composed of small cells belonging to the outermost layer of cellular tissue, with the pretty thick-sided walls very strongly coherent, so as to form a firm membrane. Its cells contain no chlorophyll. In ordinary herbs that allow of ready evaporation, this membrane is made up of a single layer of cells ; as in the Lily, Fig. 221, and the Balsam, Fig. 220. It is composed of two layers in cases where one might prove insufficient ; and in the Oleander, besides the provision against too copious evaporation, already described (263), the epidermis consists of three com- pact layers of very thick-sided cells (Fig. 222). It is generally thick, or hard and impermeable, in the firm leaves of the Pitto- sporum, Laurustinus, and other plants, which will thrive, for this very reason, where those of more delicate foliage are liable to per- ish, in the dry atmosphere of our rooms in winter. FIG 222. Magnified section through a part only of the thickness of a leaf of the Oleander, showing the epidermis of the upper surface, formed of three layers of thick-walled cells and the two very compact layers of cylindrical cells standing endwise. FIG. 223. Magnified slice of the epidermis and superficial parenchyma of a Cactus, after Schleiden ; exhibiting the epidermis (a) greatly thickened by a stratified deposition in the cells : and some cells of the parenchyma likewise nearly filled with an incrusting deposit. The depo- sition in such cases is always irregular, leaving canals or passages which nearly connect the adjacent cells. Several of the cells contain crystals (94). FIG. 224. Similar section from another species of Cactus, passing through one of the sto- mata, and the deep intercellular space beneath it. THEIR ANATOMICAL STRUCTURE. 149 265. In such firm leaves, especially, the walls of the epidermal cells are soon thickened by internal deposition (44), especially on the superficial side. This is well seen in the epidermis of the Aloe, and in other fleshy plants, Avhich hear severe drought with impunity : in Fig. 223, it is shown, at a, in the rind of a Cactus, in which the green layer of the whole stem answers the purpose of leaves. Sometimes an exterior layer of this superficial deposit in the epidermis may be detached in the form of a continuous, ap- parently structureless membrane, which Brongniart and succeeding authors have called the Cuticle. That it may shed water readily, the surface of leaves is commonly protected by a very thin varnish of wax, or else with a bloom of the same substance in the form of a whitish powder, which easily rubs off (85), as is familiarly seen in a Cabbage-leaf. 266. A thickening deposit sometimes takes place in the cells of parenchyma immediately underneath the epidermis, especially in the Cactus Family, where the once thin and delicate walls of the cells become excessively and irregularly thickened (Fig. 223, 224), so as doubtless to arrest or greatly obstruct exhalation through the rind. Something like this choking of the cells mustf commonly occur with age in most leaves, particularly those that live for more than one season (311). 267. But the multiplication of these safeguards against exhalation might be liable to defeat the very objects for which leaves are prin- cipally destined. Evaporation from the parenchyma of the leaves is essential to the plant, as it is the only method by which its exces- sively dilute food can be concentrated. Some arrangement is requi- site that shall allow of sufficient exhalation from the leaves while the plant is freely supplied with moisture by the roots, but restrain it when the supply is deficient. It is clear that the greatest demand is made upon the leaves at the very period when the supply through the roots is most likely to fail ; for the summer's sun, which acts so powerfully on the leaves, at the same time parches the soil upon which the leaves (through the rootlets) depend for the moisture they exhale. So long as their demands are promptly answered, all goes well. The greater the force of the sun's rays, the greater the speed at which the vegetable machinery is driven. But whenever the supply at the root fails, the foliage begins to flag and droop, as is so often seen under a sultry meridian sun ; and if the exhaustion pro- ceeds beyond a certain point, the leaves inevitably wither and perish. 13* 150 THE LEAVES. Some adaptation is therefore needed, analogous to a self-acting valve, which shall regulate the exhalation according to the supply. Such an office is actually fulfilled by 268. The Stomata, Stomates, or Breathing-pores (70). Through the orifices which bear this name, exhalation principally takes place, in all ordinary cases, where the epidermis is thick and firm enough to prevent much escape of moisture by direct transudation. The stomata (Fig. 225-228) are always so situated as to open directly into the hol- low chambers, or air-cavities, which pervade the parenchyma (Fig. 221), especially the lower stratum, so as to afford free communication between the external air and the whole interior of the leaf. The perforation of the epi- 235 dermis is between two (or rarely four) delicate and commonly crescent-shaped cells, which, unlike the rest of the epidermis, usually contain some chlorophyll, and in other re- spects resemble the parenchyma beneath. When moistened these guardian-cefls change their form, becoming more crescentic as they become more turgid, thereby separating in the middle and opening a free communication between the outer air and the interior of the leaf. As they become drier, they shorten and straighten, so as to bring the sides of the two into contact and close the orifice.* The use of tliis mechanism will be readily understood. So long as the leaf * They expand and contract most in the direction of their length ; and the elongation and increased curvature when moist draws in the concave side and so enlarges the aperture. The mechanism of the opening and shutting of sto- mata has been recently investigated by Mohl (in Bot. Zeitung for 1856, p. 697, — an abstract of the memoir is given by C. F. Stone in Amer. Journal of Sci- ence for March, 1857), — and these facts verified. The peculiar change of the guardian-cells in form seems not entirely susceptible of mechanical explanation, and is partly controlled (like other vegetable movements) by the light of the sun ; but it mainly depends upon endosmose. Mohl has clearly shown that, while the guardian-cells themselves act so as to open the stomate in moisture and close it in dryness, the adjacent cells of the epidermis in swelling when moist tend to close the stomate, and their contraction when dry to open it ; — so that the actual position at any time is a resultant of nicely adjusted opposing forces. FIG. 225. A highly magnified piece of the epidermis of the Garden Balsam, -with three stomata (after Brongniart). THEIR STOMATA OR BREATHING-PORES. 151 is in a moist atmosphere, and is freely supplied with sap, the sto- mates remain open, and allow the free escape of moisture by evap- oration. But when the supply fails, and the parenchyma begins to be exhausted, the guardian-cells, at least equally affected by the dry- ness, promptly collapse, and by closing these thousands of apertures check the drain the moment it becomes injurious to the plant. 269. As a general rule, the stomata wholly or principally belong to the epidermis of the lower surface of the leaf: the mechan- ism is too delicate to work well in direct sunshine. The posi- tion of the stomata, and the loose texture of the lower pa- renchyma, require that this sur- face should be shielded from the sun's too direct and intense action ; and show why leaves soon perish when artificially reversed, and pre- vented from resuming (as otherwise they spontaneously will) their natural position. This general arrangement is vai'iously modified, however, under peculiar circumstances. The stomata are equally distributed on the two sides of those leaves, of whatever sort, which grow in an erect position, or present their edges, instead of their surfaces, to the earth and sky (294), and have the parenchyma of both sides similarly constituted, sustaining consequently the same relations to light. In the Water-Lilies (Nymphosa, Nuphar), and other leaves which float upon the water, the stomata all belong to the upper surface. All leaves which live under water, where there can be no evaporation, are destitute, not only of stomata, but usually of a distinct epidermis also. 270. The number of the stomata varies in different leaves from 800 to about 170,000 on the square inch of surface. In the Apple, there are said to be about 24,000 to the square inch (which is under the average number, as given in a table of 36 species by Lindley) ; so that each leaf of that tree would present about 100,000 of these orifices. When the stomata are not all restricted to the lower sur- face, still the greater portion usually occupy this position. Thus, the leaf of Arum Dracontium is said to have 8,000 stomata to a square inch of the upper surface, and twice that number in the FIG. 226. Magnified view of the 10,000th part of a square inch of the epidermis of the lower surface of the leaf of the White Lily, with its stomates. 227. A single stomate, more magnified. 228. Another stomate, widely open. 152 THE LEAVES. same space of the lower. The leaf of the Coltsfoot has 12,000 stomata to a square inch of the lower epidermis, and only 1,200 in the upper. That of the White Lily has from 20,000 to G0,000 to the square inch on the lower surface, and perhaps 3,000 on the up- per. In this plant, and in other true Lilies, they are so remarkably large (Fig. 221, 226 — 228) that they may he discerned by a simple lens of an inch focus. In most plants they are very much smaller than this. 271. Succulent or fleshy plants, such as those of the Cactus tribe, Mesembryanthemums, Sedums, Aloes, &c.,are remarkable for holding the water they imbibe with great tenacity, rather in consequence of the thickness of the epidermis, or from the deposit which early ac- cumulates in the superficial cells of the parenchyma (2GG), than from the want of stomata. The latter are usually abundant,* but they seem to open less than in ordinary plants, except in young and growing parts. Hence the tissue becomes gorged as it were with fluid, which is retained with great tenacity, especially during the hot season. They are evidently constructed for enduring severe droughts ; and are accordingly found to inhabit dry and sunburnt places, such as the arid plains of Africa, — the principal home of the Stapelias, Aloes, succulent Euphorbias, &c, — or the hottest and driest parts of our own continent, to which the whole Cactus family is indigenous. Or, when such plants inhabit the cooler temperate regions, like the Sedums and the common Houseleek, &c, they are commonly found in the most arid situations, on naked rocks, old walls, or sandy plains, exposed to >the fiercest rays of the noonday sun, and thriving where ordinary plants would speedily perish. The drier the atmosphere, the greater their apparent reluctance to part with the fluid they have accumulated, and upon which they live during the long period when little or no moisture is yielded by the soil or the air. Their structure and economy fully explain their tolerance of the very dry air of our houses in midwinter, when or- dinary thin-leaved plants become unhealthy or perish. 272. Sometimes the leaves of succulent plants merely become obese or misshapen, like those of the Ice-plant and other species * The thickened epidermis of the fleshy leaves of the Sea-Sand wort (Hon- kenya) is provided with an abundance of large stomata, on the upper as well as the lower face. But this plant, though very fleshy, grows in situations where its roots are always supplied with moisture. THEIR DEVELOPMENT, ETC. 153 of Mesembryanthemum, &c. : sometimes they are reduced to tri- angular projections or points, or are perfectly confounded with the green bark of the stem, which fulfils their office, as in the Stapelia and most Cacti. 273. The Development of leaves. At their first appearance, each leaf is a minute papilla or projection of parenchyma on the nascent axis : as it grows, this shapes itself into the blade, and is eliminated from the axis. The petiole, if any, is later formed, and by its growth raises the blade from the stem. Commonly the apex of the blade first appears, and the formation proceeds from above down- wards. The sheath at the base (as in most Monocotyledons), or the stipules (259, which principally belong to Dicotyledons), are at first continuous with the blade, or divided from it by a mere con- striction : the formation and elongation of the petiole soon separate them. The stipules, remaining next the axis or source of nourish- ment, undergo a rapid development early in the bud, so that, at a certain stage, they are often larger than the body of the leaf, and they accordingly form in such cases the teguments of the bud. Divided or lobed and compound leaves are simple at the commence- ment, but the lobes are very early developed ; they grow in respect to the axis of the leaf nearly as that grew from the axis of the plant, and in the compound leaf at length isolate themselves, and are often raised on footstalks of their own. Commonly the upper lobes or leaflets are first formed, and then the lower : but in those of the TValnut and Ailanthus, and other large compound leaves, the formation proceeds from below upwards, and new leaflets continue to be produced from the apex, even after the lowermost are nearly full grown. In the earliest stage leaves consist of parenchyma alone: the fibro-vascular tissue which makes the ribs, veins, or framework appears later. 274. At the points on the surface of the developing leaf where stomata are about to be formed, one of the epidermal cells early ceases to enlarge and thicken with the rest, but divides into two (in the manner formerly described, 33), forming the two guardian-cells of the stomate : as they grow, the two constituent portions of their common partition separate, leaving an interspace or orifice between. In some cases, each new cell divides again, when the stomate is formed of four cells in place of two. 275. The Forms Of Leaves are almost infinitely various. These afford some of the readiest, if not the most certain, marks for 154 THE LEAVES. characterizing species. Their principal modifications are therefore classified, minutely defined, and embodied in a system of nomen- clature which is equally applicable to other parts of the plant, and which as an instrument is indispensable to the systematic botanist. The numerous technical terms which have gradually accumulated from the infancy of the science, and have multiplied with its increas- ing wants, are mostly quite arbitrary, or have been suggested by real or fancied resemblances of their shapes to various natural or other objects. This arbitrary nomenclature, which formerly severe- ly tasked the memory of the student, was reduced by De Candolle to a clear and consistent system, based upon scientific principles, and of easy application. The fundamental idea of the plan is, that the almost infinite varieties in the form and outline of leaves may be deduced from the different modes and degrees in which the woody skeleton or framework of the leaf is expanded or ramified in the parenchyma. Upon this conception the following sketch is based ; in which all the more important terms of the nomenclature of leaves are mentioned and defined. It should be kept in mind, however, that this is not to be taken as an explanation of the actual formation of leaves ; but rather as an account of the mutual adap- tation and correspondence of their outlines and framework. For the parenchyma is developed, and the form of the leaf more or less determined, before the framework has an existence. The latter, therefore, cannot have given rise to the outline or shape of the organ. Tbe distribution of the veins or fibrous framework of the leaf in the blade is termed its 27G. Venation. The veins are distributed throughout the lamina in two principal modes. Either the vessels of the petiole divide at once, where they enter the blade, into several veins, which run parallel with each other to the apex, connected only by simple transverse veinlets (as in Fig. 230) ; or the petiole is continued into the blade in the form of one or more principal or coarser veins, which send off branches on both sides, the smaller branch- lets uniting with one another {anastomosing) and forming a kind of network ; as in Fig. 229. The former are termed parallel- veined, or commonly nerved leaves ; the veins in this case having been called nerves by the older botanists, — a name which it is found convenient to retain, although of course they are in no respect analogous to the nerves of animals. The latter are termed reticu- lated or netted-veined leaves. THEIR VENATION. 155 277. Parallel-veined or nerved leaves are characteristic of En- dogenous plants ; while reticulated leaves are almost universal in Exogenous plants. We are thus furnished with a very obvious, al- though by no means absolute, distinction between these two great classes of plants, independently of the structure of their stems (198). 278. In reticulated leaves, the coarse primary veins (one or more in number), which proceed immediately from the apex of the petiole, are called ribs ; the branches are termed veins, and their subordinate ramifications, veinlets. Very frequently, a single strong rib (called the midrib), forming a continuation of the petiole, runs directly through the middle of the blade to the apex (Fig. 229, 238, &c), and from it the lateral veins all diverge. Such leaves are termed feather-veined or pinnately veined ; and are subject to vari- ous modifications, according to the arrangement of the veins and vein- lets ; the primary veins sometimes passing straight from the midrib to the margin, as in the Beech and Chestnut (Fig. 238) ; while in other cases they are divided into veinlets long before they reach the margin. When the midrib gives off a very strong primary vein or branch on each side above the base, the leaf is said to be triple- ribbed, or often tripli-nerved, as in the common Sunflower (Fig. FIG. 229. A leaf of the Quince, of the netted-vcined or reticulated sort : b, blade : p, petiole or leaf -stalk : st, stipules. FIG. 230. Parallel- veined leaf of the Lily of the Valley. 156 THE LEAVES. 241) ; if two such ribs proceed from each side of the midrib, it is said to be quintuple-ribbed, or quintupli-nerved. 279. Not unfrequently the vessels of a reticulated leaf divide at the apex of the petiole into three or more portions or ribs of nearly- equal size, which are usually divergent, each giving off veins and veinlets, like the single rib of a feather-veined leaf. Such leaves are termed radiated-veined, or palmately-veined ; and, as to the number of the ribs, are called three-ribbed, five-ribbed, seven-ribbed, &c. (Fig. 244, 247, 253). Examples of this form are furnished by the Maple, the Gooseberry, the Mallow family, &c. Occasionally the ribs of a radiated-veined leaf converge and run to the apex of the blade, as in Rhexia and other plants of the same family, thus resem- bling a parallel-veined or nerved leaf; from which, however, it is distinguished by the intermediate netted veins. But when the ribs are not very strong, such leaves are frequently said to be nerved, although they branch before reaching the apex. 280. According to the theory of De Candolle (275), the shape which leaves assume may be viewed as dependent upon the dis- tribution of the veins, and the quantity of parenchyma ; the gen- eral outline being determined by the division and direction of the veins ; and the form of the margin, (whether even and continuous, or else interrupted by void spaces or indentations,) by the greater or FIG. 231-244. Various forms of simple leaves. THKIR FORMS. 157 less abundance of the parenchyma in which the veins are distrib- uted. This view is readily intelligible upon the supposition that a 245 247 248 ' /V~-JSt~~. leaf is an expansion of soft parenchyma, in which the firmer veins are variously ramified. Thus, if the principal veins of a feather- veined leaf are not greatly prolonged, and are somewhat equal in length, the blade Avill have a more or less elongated form. If the veins are very short in proportion to the midrib, and equal in length, the leaf will be linear (as in Fig. 240) ; if longer in proportion, but still equal, the leaf will assume an oblong form (Fig. 242), which a slight rounding of the sides converts into an oval or ellip- tical outline. If the veins next the base are longest, and especially if they curve forward towards their extremities, the leaf assumes a lanceolate (Fig. 239), ovate (Fig. 241), or some intermediate form. On the other hand, if the veins are more developed beyond the mid- dle of the blade, the leaf becomes obovate (Fig. 232), or cuneiform (Fig. 235). In radiated or palmately veined leaves (Fig. 245-253), where the primary ribs are divergent, an orbicular or roundish out- line is most common. When some of the ribs or their ramifications are directed backwards, a recess, or sinus, as it is termed, is pro- duced at the base of the leaf, which, taken in connection with the general form, gives rise to such terms as cordate or heart-shaped (Fig. 244), reniform or kidney-shaped (Fig. 245), &c, when the posterior portions are rounded ; and those of sagittate or arrow- headed (Fig. 252), and hastate or halberd-shaped (Fig. 250), when FIG. 245 - 253. Forms of simple, chiefly radiated-veined leaves. 14 158 THE LEAVES. the angles or lobes at the base diverge. The margins of the sinus are sometimes brought into contact and united, when the leaf be- comes peltate or shield-shaped (Fig. 248) ; the blade being attached to the petiole, not by its apparent base, but by some part of the lower surface. Two or three common species of Hydrocotyle plainly exhibit the transition from common radiated leaves into the peltate form. Thus, the leaf of H. Americana (Fig. 247) is round- ish-reniform, with an open sinus at the base, while in H. inter- rupta and H. umbellata (Fig. 248), the margins have grown to- gether so as to obliterate the sinus, and an orbicular peltate leaf is produced. In nerved leaves, when the nerves run parallel from the base to the apex, as in Grasses (Fig. 237), the leaf is necessa- rily linear, or nearly so ; but when they are more divergent in the middle, or towards the base, the leaf becomes oblong, oval, or ovate, &c. (Fig. 243). In one class of nerved or parallel-veined leaves, the simple veins or nerves arise from a prolongation of the petiole in the form of a thickened midrib, instead of the base of the blade, constitut- ing the curvinerved leaves of De Candolle. This structure is almost universal in the Ginger tribe, the Arrowroot tribe, in the Banana, and other tropical plants ; and our common Pontederia, or Pickerel-weed (Fig. 236), affords an illustration of it, in which the nerves are curved backwards at the base, so as to produce a cordate outline. 281. As to the margin and particular outline of leaves, they ex- hibit every gradation between the case where the blade is entire, that is, with the margin perfectly continuous and even (as in Fig. 243), and those where it is cleft or divided into separate portions. The convenient hypothesis of De Candolle connects these forms with the abundance or scantiness of the parenchyma, compared with the divergence and the extent of the ribs or veins ; on the supposition that, where the former is insufficient completely to fill up the framework, lobes, incisions, or toothings are necessarily produced, extending from the margin towards the centre. Thus, in the white and the yellow species of Water Ranunculus, there appears to be barely sufficient parenchyma to form a thin covering for each vein and its branches (Fig. 251, the lowest leaf) ; such leaves are said to be Jiliformhj dissected, that is, cut into threads ; the nomenclature in all these cases being founded on the conven- ient (but incorrect) supposition, that a leaf originally entire is cut into teeth, lobes, divisions, &c. If, while the framework remains the same as in the last instance, the parenchyma be more abun- THEIR FORMS. 159 dantly developed, as in fact happens in the upper leaves of the same species when they grow out of water, and is shown in the same figure, they are merely cleft or lobed. If these lobes grow together nearly to the ex- tremity of the principal veins, the leaf is only toothed, serrated, or crenated; and if the small re- maining notches were filled with parenchyma, the leaf would be en- tire. The study of the development of leaves, however, proves that the parenchyma grows and shapes the outlines of the organ in its own Avay, irrespec- tive of the framework, which is, in fact, adapted to the parenchyma rather than the parenchyma to it. The principal terms which designate the mode and degree of division in simple leaves may now be briefly explained, without further reference to this or any other theory. 282. A leaf is said to be serrate, when the margin is beset with sharp teeth which point forwards towards the apex (Fig. 254) ; dentate, or toothed, when the sharp salient teeth are not directed towards the apex of the leaf (Fig. 255) ; and crenate, when the teeth are rounded (Fig. 248, 25 G). A slightly waved or sinuous margin is said to be repand (Fig. 257) ; a more strongly uneven margin, with alternate rounded concavities and convexities, is termed sinuate (Fig. 258). When the leaf is irregularly and sharply cut deep into the blade, it is said to be incised (Fig. 259) ; when the portions (or segments) are more definite, it is said to be lobed (Fig. 260, 264) ; and the terms two-lobed, three-lobed (Fig. 2Qi),five-lobecl, &c, express the number of the segments. If the incisions extend about to the middle of the blade, or somewhat deeper, and especially if the sinuses are acute, the leaf is said to be cleft (Fig. 261, 265) ; and the terms two-cleft, three-cleft (Fig. 265), &c. (or in the Latin form, bifid, trifid, &c.), designate the number of the segments : or when the latter are numerous or indefinite, the leaf is termed many-cleft, or multifid. If the segments extend nearly, but not quite, to the FIG. 254-259. Forms of leaves as to the toothing of their margins. 160 THE LEAVES. base of the blade or the midrib, the leaf is said to be parted (Fig. 262, 266) : if they reach the midrib or the base, so as to interrupt the parenchyma, the leaf is said to be divided (Fig. 263, 267) ; the number of partitions or divisions being designated, as before, by the terms two-, three-, Jive-parted, or two-, three-, jive-divided, &c. 283. As the mode of division always coincides with the arrange- ment of the primary veins, the lobes or incisions of feather-veined, are differently arranged from those of radiated or palmately veined leaves : in the latter, the principal incisions are all directed to the base of the leaf; in the former, towards the midrib. These modi- fications are accurately described by tenns indicative of the vena- tion, combined with those that express the degree of division. Thus, a feather-viened (in the Latin form, a pinnately veined) leaf is said to be pinnately cleft or pinnatifid (Fig. 261), when the sinuses reach half-way to the midrib ; pinnately parted, when they extend almost to the midrib (Fig. 262) ; and pinnately divided, when they reach the midrib, dividing the parenchyma into separate portions (Fig. 263). A few subordinate modifications are in- dicated by special terms : thus, a pinnatifid or pinnately parted leaf, with regular, very close and narrow divisions, like the teeth of a comb, is said to be pectinate ; a feather-veined leaf, more or less pinnatifid, but with the lobes decreasing in size towards the base, is FIG. 260-267. Pinnately and palmately lobed, cleft, parted, and divided leaves. THEIR FORMS. 161 termed lyrate, or lyre-shaped (Fig. 278) ; and a lyrate leaf with sharp lobes pointing towards the base, as in the Dandelion (Fig. 279), is called runcinate. A pahnately veined leaf is in like man- ner said to he pahnately lobed (Fig. 2G4), pahnately cleft (Fig. 265), pahnately parted (Fig. 266), or 'pahnately divided (Fig. 267), ac- cording to the degree of division. The term palmate was originally employed to designate a leaf more or less deeply cut into about five spreading lobes, bearing some resemblance to a hand with the fingers spreading ; and it is still used to designate a pahnately lobed leaf, without reference to the depth of the sinuses. A palmate leaf Avith the lateral lobes cleft into two or more segments is said to be pedate (Fig. 249), from a fancied resemblance to a bird's foot. By desig- nating the number of the lobes in connection with the terms which indicate their extent and their disposition, botanists are enabled to describe all these modifications with great brevity and precision. Thus, a pahnately three-parted leaf is one of the radiated- veined kind, which is divided almost to the base into three segments (Fig. 266) ; a pi nnately jive-parted leaf is one of the feather-veined kind cut into five lobes (two on each side, and one terminal), with the sinuses ex- tending almost to the midrib : and the same plan is followed in de- scribing cleft, lobed, or divided leaves. 284. The segments of a lobed or divided leaf may be again di- vided, lobed, or cleft, in the same way as the original blade, and the same terms are employed in describing them. Sometimes both the primary, secondary, and even tertiary divisions are defined by a single word or phrase ; as bipinnatijid (Fig. 280), tripinnatijid, bip innately parted, tripinnately parted, twice pahnately parted, &c. 285. Parallel-veined or nerved leaves would naturally be ex- pected to present entire margins, and this they almost universally do when the nerves are convergent (Fig. 230, 243). Such leaves are often lobed or cleft when the principal nerves diverge greatly, as in the Dragon Arum ; but the lobes themselves are entire. 286. There are a few terms employed in describing the apex of a leaf, which may be here enumerated. When a leaf tapers to a FIG. 268-276. Forms of the apex of leaves. 14* 162 THE LEAVES. narrowed or slender apex, it is said to be acuminate (Fig. 268) : when it terminates in an acute angle, it is said to be acute (Fig. 269) : when the apex is an obtuse angle, or rounded, it is termed obtuse (Fig. 270) : an obtuse leaf, with the apex slightly indented or depi'essed in the middle, is said to be retuse (Fig. 272), or, if more strongly notched, ernarginate (Fig. 273) : an obovate leaf with a wider and more conspicuous notch at the apex is termed obcordate (Fig. 274), being a cordate or heart-shaped leaf inverted. When the apex is, as it were, cut off by a straight transverse line, the leaf is said to be truncate (Fig. 271) : when abruptly terminated by a small and slender projecting point, it is mucronate (Fig. 276) : when tipped with a stronger and rigid projecting point, or cusp, it is cuspi- date (Fig. 275). 287. All these terms are equally applicable to expanded sur- faces of every kind, such as petals, sepals, &c. : and those terms which are used to describe the modifications of solid bodies, such as stems and stalks, are equally applicable to leaves when these affect similar shapes, as they sometimes do. 288. The whole account, thus far, relates to Simple Leaves, namely, to those which have a blade of one piece, however cleft or lobed, or, if divided, where the separate portions are neither raised on 235 £86 FIG 277-287. Various forms of lobed and compound leaves. COMPOUND LEAVES. 163 stalklets of their own, nor articulated (by a joint) Avith the main petiole, so that the pieces are at length detached and fall separately. The distinction, however, cannot he very strictly maintained ; there are so many transitions between simple and 289. Compound Leaves. These have the blade divided into entire- ly separate pieces ; or, rather, they consist of a number of blades, borne on a common petiole, usually supported on stalklets of their own, between which and the main petiole an articulation or joint is formed, more or less distinctly. These separate blades are called Leaflets : they present all the diversities of form, outline, or division which simple leaves exhibit ; and the same terms are em- ployed in characterizing them. Having the same nature and origin as the lobes or segments of simple leaves, they are arranged in the same ways on the common petiole. Compound leaves accordingly occur under two general forms, the pinnate and the palmate (other- wise called digitate). 290. The pinnate form is produced when a leaf of the pinnately veined sort becomes compound ; that is, the leaflets are situated along the sides of the common petiole. There are several modifica- tions of the pinnate leaf. It is abruptly pinnate, when the leaflets are even in number, and none is borne on the very apex of the petiole or its branches, as in Cassia (Fig. 290), and also in the Vetch tribe, where, however, the apex of the petiole is generally prolonged into a tendril (Fig. 287, 289). It is impari-pinnate, or pinnate with an odd leaflet, when the petiole is terminated with a FIG. 288 - 290. Simply pinnate leaves of various forms. 164 THE LEAVES. leaflet (Fig. 281, 288). There are some subordinate modifications ; sucli as lyrately pinnate, when the blade of a lyrate leaf (Fig. 278) is completely divided, as in Fig. 285 ; and interruptedly pinnate, when some minute leaflets are irregularly intermixed with larger ones, as is also shown to some extent in the figure last cited. The number of leaflets varies from a great number to very few. When reduced to a small number, such a leaf is said to be pinnately seven-, or jive-, or tri-foliolate, as the case may be. A pinnate leaf of three or five leaflets is often called ternate or quinate ; which terms, how- ever, are equally applied to a palmately compound leaf, and also, and more appropriately, to the case of three or five simple leaves growing on the same node. A pinnately trifoliolate leaf (Fig. 286) is readily distinguished by having the two lateral leaflets attached to the petiole at some distance below its apex, and by the joint which is observable at some point between their insertion and the lamina of the terminal leaflet. Such a leaf may even be reduced to a single leaflet ; as in the Orange (Fig. 283) and the primordial leaves of the common Barberry. This is distinguished from a really simple leaf by the joint at the junction of the partial with the general petiole. 291. The palmate or digitate form is produced when a leaf of the palmately veined sort becomes compound ; in which case the leaflets are necessarily all attached to the apex of the common petiole, as in the Horsechestnut and Buckeye (Fig. 277), and the common Clover (Fig. 304). Such leaves of three, five, or any definite number of leaflets, are termed palmately (or digitately) trifoliolate, five-foliolate, &c. A leaf of two leaflets, which rarely occurs, is unijugate (one- paired) or binate. By this nomenclature, the distinction between pinnately and palmately compound leaves is readily kept up, and every important character of a leaf is expressed with brevity and accuracy. 292. The stalk of a leaflet is called a partial petiole (petiolule) ; and the leaflet thus supported is petiolulate. The partial petioles may bear a set of leaflets, instead of a single one, when the leaf becomes doubly or twice compound. Thus a pinnate leaf again com- pounded in the same way becomes bipinnate (Fig. 282), or if still a third time divided it is tripinnate, &c. In these cases the main divisions or branches of the common petiole are called pinnae, or the pairs jugce. So a trifoliolate leaf twice compound becomes biternate (Fig. 284) ; or thrice, tritemate, &c. When the primary division VERTICAL AND PERFOLIATE LEAVES. 165 is digitate, the secondary division is often pinnate, thus combining the two modes in the same leaf. A leaf irregularly or indeter- minately several times compounded, in whatever mode, is said to be decompound. 293. Leaves of Peculiar Conformation. The blade of a leaf is almost always symmetrical, that is, the portions on each side of the midrib or axis are similar ; but occasionally one side is more developed than the other, when the leaf is oblique, as is strikingly the case in the species of Begonia (Fig. 246) of our conservatories. 294. Vertical and Equitant Leaves. The blade is also commonly horizontal, presenting one surface to the sky, and the other to the earth ; in which case the two surfaces differ in structure (262) as well as in appearance, each being fitted for its peculiar of- fices : if artificially reversed, they spontaneously resume their natural position, or soon perish if prevented from doing so. But in erect and verti- cal leaves, the two surfaces are equally exposed to the light, and are similar in structure and ap- pearance. In such erect and equitant leaves as those of Iris (Fig. 291), it is really the lower sur- face that is presented to the air ; for the leaf is folded together lengthwise (con-duplicate), and consoli- dated while in the nascent state, so that the true upper surface is concealed in the interior, except near the base, where they alternately cover over each other in the equitant manner (258, Fig. 292). True vertical leaves, which present their edges instead of their surfaces to the earth and sky, generally assume this position by a twisting of the base or the petiole ; as is strikingly seen in the Callistemon and many other Australian trees of the Myrtle family, some of which are now com- mon in green-houses. 295. Perfoliate Leaves. While in Iris the two halves of the FIG. 291. Equitant erect leaves of Iris, with the rootstock. FIG. 292. A section across these leaves at the base, showiDg their equitant character. 166 THE LEAVES, upper surface of a folded leaf cohere, those of some other plants ex- hibit a cohesion by their contiguous edges, and give rise to a differ- ent anomaly. This is illustrated by peltate leaves (Fig. 248), and more strikingly by what are termed perfoliate leaves. These in some cases originate from the union of the bases of a pair of opposite sessile leaves (con- nate^perfoliate), as in Silphium perfoliatum, Triosteum perfo- liatum, and the upper pairs of true Honeysuckle (Fig. 294). In others they con- sist of a single clasping leaf, the posterior lobes of which encompass the stem and cohere on the opposite side, as is seen in Bu- pleurum rotundifolium, Uvularia perfo- liata, and Baptisia perfoliata (Fig. 293). 296. Leaves with no distinction of Blade and Petiole. The leaves of the Iris, as well as those of the Daffodil, the Onion, and of many other Endogens, show no distinction of blade and petiole. In some the leaf of this sort may be regarded as a sessile blade ; in others, rather as a petiole per- forming the functions of a blade. Leaves are not always expanded bodies. Sometimes they are filiform or thread-shaped, as those of Asparagus : some are acicular, acerose, or needle-shaped, as in Pines and Larches (Fig. 212, 213) ; others are subulate or awl-shaped, as in Juniper, &c. The Red Cedar and Arbor Vitas (Fig. 295) exhibit both awl-shaped and scale-shaped leaves on different branchlets. 297. Succulent or Fleshy Leaves, like those of Stonecrop, House- leek, Mesembryanthemum or Ice-Plant, and the Agave or Century- Plant, usually assume shapes more or less unlike ordinary foliage. Some of them are terete, like stems, or at least have no distinct upper and lower surface. These greatly thickened leaves serve a FIG. 293. Perfoliate (single) leaves of Baptisia perfoliata. FIG. 294. Connate-perfoliate leaves of a wild Honeysuckle (Lonicera flava). AS BUD-SCALES, TENDRILS, SPINES, ETC. 167 double purpose, being not only organs for assimilation, — the general office of foliage, — but also repositories in which assimilated matter is stored up, just as in the root of the Beet and Radish (Fig. 138), or in subter- ranean stems or branches in rootstocks, tubers, and corms ( 188 - 190, 194). The bases of those leaves which form the scales of bulbs (191) are turned to the same use. In Fig. 176 we have a leaf the blade of which acts as foliage in the ordi- nary manner of leaves, while its subterranean thickened base serves as a repository of nutri- ment which the blade has elaborated. The very first leaves of the plant, viz. the cotyledons or seed-leaves (120 — 123) are commonly subservi- ent to this purpose, and some- times to no other, as in the Pea, Horsechestnut, Oak, &c. (124), where these leaves are mere repositories of food for the use of the germinating plant. '298. Leaves as Bud-scales, &c. (161) exhibit the same organ under a different modification, and subserving a different special purpose. Of the same nature are the degenerated or abortive scale-like leaves on the vernal stems of peren- nial herbs near or beneath the surface of the ground, and on Asparagus shoots, and also those scales which colored parasitic plants produce in place of foliage (152). The primary leaves of Pines are all thin and dry bud-scales ; the actual foliage originating from a branch in the axil of each (Fig. 212). 299. Leaves as Tendrils are seen in the proper Pea tribe ; where however only the extremity of the common petiole is transformed in this manner (Fig. 287, 289) ; but in one plant of the kind (Lathyrus Aphaca) the whole leaf becomes a tendril. 300. Leaves as Spines occur in several plants. The primary leaves FIG. 295. A twig of American Arbor Vitse, exhibiting both awl-shaped and scale-shaped leaves. FIG. 296. A summer shoot of the Barberry, showing a lower leaf in the normal state ; the next partially, those still higher completely, transformed into spines. 168 THE LEAVES, of the shoots of the common Barberry offer a familiar instance of the kind (Fig. 29G). The most extraordinary modification of the leaf occurs in the 301. Fly-traps of Dionrea muscipula, the Venus's Fly-trap of North Carolina (which is found only in the vicinity of Wilming- ton, where it abounds in wet and sandy bogs). Each i leaf of this most curious plant bears at its summit an append- age (answering, perhaps, to the proper blade), which opens and shuts : fringed with strong bristles or slender teeth on its margin, it bears some resemblance to a steel-trap, and operates much like one. For when open, as it commonly is when the sun shines, no sooner does a fly alight on its surface, and brush against any one of the several long bristles that grow there, than the trap suddenly closes, often capturing the intruder, pressing it all the harder for its struggles, and commonly depriving it of life. After all movement has ceased within, the trap slowly opens, and is ready for another capture. Why this plant catches insects, we are unable to say ; and as to the mechanism of the movement it is no more and no less explicable than the much slower movements of ordinary leaves in changing their position. FIG. 297. A plant of Dionaea muscipula, reduced in size. 298. Three of the leaves, of nearly the natural size ; one of them open, the others closed. AS ASCIDIA OR PITCHERS. 169 302. Ascidia or Pitchers, or tubes open at the summit, represent another remarkable form of leaves. These occur in several plants of widely different families. If we conceive the margins of the dilated part of the leaf of Dionasa to curve inwards until they meet, and cohere with each other, there would result a leaf in form not unlike that of Sarracenia purpurea, the common Pitcher-plant or Sidesaddle Flower of the Northern United States (Fig. 300). So the tube or pitcher has been supposed to answer to the petiole, and the hood at the summit to the blade. And this view is strengthened by a Pitcher-plant of the same family (Heliamphora, Fig. 299), discovered by Mr. Schomburgk in the mountains of British Guiana, in which the pitcher is not always completed quite to the summit, and the hood is represented by a small concave terminal appendage. In the curious Nepenthes (Fig. 301), the petiole is first dilated into a kind of lamina, then contracted into a tendril, and finally dilated into a pitcher, containing fluid secreted by the plant itself; the orifice being accurately closed by a lid, which from analogy was supposed to represent the real blade of the leaf. The study of the development, however (recently made by Dr. Hooker), does not confirm this hypothesis. The whole pitcher of Nepenthes is only an anom- alous appendage of the tendril-like prolongation of the midrib of the real blade of the leaf. A new Pitcher-plant of the Sarracenia family (the Darlingtonia), discovered by Mr. Brackenridge in California, FIG. 299. Pitchers of Heliamphora ; 300, of Sarracenia purpurea ; 301, of Nepenthes. 302. A phyllodiuin of a New Holland Acacia. 303. The same, bearing a reduced compound blade. 15 170 THE LEAVES. has recently been made known by Dr. Torrey. In this the enlarged summit of the tube is strongly arched like a hood (as in Sarracenia psittacina of the Southern States), and is abruptly terminated by a singular two-lobed foliaceous appendage, resembling the forked tail of a fish. 303. TllC Petiole, or Leafstalk, is usually either round, or half-cylin- drical and channelled on the upper side. But in the Aspen, it is strongly flattened at right angles with the blade, so that the slightest breath of air puts the leaves in motion. It is not unfrequently fur- nished with a leaf-like border, or ring ; which, in the Sweet Pea of the gardens, extends downward along the stem, on which the leaves are then said to be decurrent ; or the stalk or stem thus bordered is said to be alate or winged. In many Umbelliferous plants, the petiole is dilated below into a broad and membranaceous inflated sheath ; and in a great number of Endogenous plants the petiole consists of a sheath, embracing the stem, which in Grasses is fur- nished at the summit with a membranous appendage, in some sort equivalent to the stipules, called the ligide (Fig. 237). The woody and vascular tissue runs lengthwise through the petiole, in the form usually of a definite number of parallel threads, to be ramified in the blade. The ends of these threads are apparent on the base of the leafstalk when it falls off, and on the scar left on the stem, as so many round dots (Fig. 153, b), of a uniform number and arrange- ment in each species. 304. Fhyllodia (Fig. 302, 303). Occasionally the whole petiole dilates into a kind of blade, traversed by ribs, mostly of the parallel- veined kind. In these cases the proper blade of the leaf commonly disappears ; this substitute, called a Phyllodium (meaning a leaf-like body), taking its place. These phyllodia constitute the whole foliage of the numerous Australian Acacias. Here they are at once dis- tinguished from leaves with a true blade by being entire and parallel- veined ; while their proper leaves (of which the earlier ones uni- formly appear in germination, and also later ones in casual instances) are compound and netted-veined. They are also to be recognized by their uniformly vertical position, presenting their margins instead of their surfaces to the earth and sky ; and they sometimes bear a true compound lamina at the apex, as in Fig. 303. 305. Stipules (259, Fig. 229) are lateral appendages of leaves, usually appearing as small foliaceous bodies, one on each side of the base of the petiole. They are not found at all in a great number of STIPULES. 171 plants ; but their presence or absence is usually uniform throughout a natural order. Stipules assume a great variety of forms analogous to those of the blade. Like it they are sometimes membranaceous or scale-like, and sometimes transformed into spines, as in the Locust- tree, &c. They are sometimes present on developing shoots only ; as in the Beech, the Fig, and the Magnolia (Fig. 155, 15G), where they form the covering of the buds, but fall away as the leaves expand. They have a strong tendency to cohere with each other, or with the base of the petiole. Thus, in the Clover (Fig. 304), the Strawberry, and the Rose (Fig. 281), a stipule ad- heres to each side of the base of the petiole ; in the Plane-tree, the two are free from the petiole, but cohere by their outer margins, so as to form an apparently single stipule opposite the leaf. In other cases, both margins are united, forming a sheath around the stem, just above the leaf: these are called intrafoliaceous stipules ; and when membranaceous, as in Polygo- num (Fig. 305), they have been termed ochrece. When opposite leaves have stipules, they usually occupy the space between the petioles on each side, and are termed interpetiolar. The stipules of each leaf (one on each side), being thus placed in contact, frequently unite mi so as to form apparently but a single pair of stipules for each pair of leaves ; instances of which are very common in the order Eubiaceae. 306. Leaves furnished with stipules are said to be stipulate : when destitute of them, exstipulate. The leaflets of compound leaves are sometimes provided with small stipules (termed stipelles) of their own, as in the Bean (Fig. 286) ; Avhen they are said to be stipellate. FIG. 304. A leaf of Red Clover, with its three leaflets at the summit of the leafstalk, to which at the base the stipules (st) are adherent, one on each side. FIG. 305. Part of a leaf of Polygonum orientale, with its stipules united into a sheath {ochrea) and surrounding the stem. 172 THE LEAVES. Sect. III. The Duration of Leaves, and the General Action of Foliage. 307. Leaves last only for a limited period, and are thrown off, or else perish and decay on the stem, after having fulfilled their office for a certain time. 308. Duration Of Leaves. In view of their duration, leaves are called fugacious, when they fall off soon after their appearance ; deciduous, when they last only for a single season ; and persist- ent, when they remain through the cold season, or other interval during which vegetation is interrupted, and until after the appear- ance of new leaves, so that the stem is never leafless ; as in Ever- greens. 309. Leaves last only for a single year in many Evergreens, as well as in deciduous-leaved plants ; the old leaves falling soon after those of the ensuing season are expanded, or, if they remain longer, ceasing to bear any active part in the economy of the vegetable, and soon losing their vitality altogether. In Pines and Firs, how- ever, although there is an annual fall of leaves either in autumn or spring, yet these were the produce of some season earlier than the last ; and the branches are continually clothed with the foliage of from two to five, or even eight or ten, successive years. On the other hand, it is seldom that all the leaves of an herb endure through the whole growing season, the earlier foliage near the base of the stem perishing while fresh leaves are still appearing above. In our deciduous trees and shrubs, however, the leaves of the season are mostly developed within a short period, and they all perish nearly at the same time. They are not destroyed by frost, as is commonly supposed ; for they begin to languish, and often assume their autumnal tints (as happens with the Red Maple especially), or even fall, before the earlier frosts ; and when vernal vegetation is destroyed by frost, the leaves blacken and wither, but do not fall off entire, as they do in autumn. Some leaves are cast off, indeed, while their tissues have by no means lost their vital- ity. Death is often rather a consequence than the cause of the fall. Others die and decay on the stem without falling, as in Palms and most Endogens. In some cases many of the dead leaves hang on the branches through the winter, as in the Beech, falling only Avhen the new buds expand, the following spring. We THEIR DEATH AND FALL. 173 must therefore distinguish between the death and the fall of the leaf. 310. The Fall Of the Leaf is owing to an organic separation, through an articulation, or joint, which forms between the base of the petiole and the surface of the stem on which it rests. The forma- tion of the articulation is a vital process, a kind of disintegration of a transverse layer of cells, which cuts off the petiole by a regular line, in a perfectly uniform manner in each species, leaving a clean scar at the insertion (Fig. 153, 155). The solution of continuity begins in the epidermis, where a faint line marks the position of the future joint while the leaf is still young and vigorous : later, the line of demarcation becomes well marked, internally as well as ex- ternally ; the disintegrating process advances from without inwards, until it reaches the woody bundles ; and the side next the stem, which is to form the surface of the scar, has a layer of cells con- densed into what appears like a prolongation of the epidermis, so that, when the leaf separates, "the tree does not suffer from the effects of an open wound." " The provision for the separation being once complete, it requires little to effect it ; a desiccation of one side of the leafstalk, by causing an effort of torsion, will readily break through the small remains of the fibro-vascular bundles ; or the in- creased size of the coming leaf-bud will snap them ; or, if these causes are not in operation, a gust of wind, a heavy shower, or even the simple weight of the lamina, will be enough to disrupt the small connections and send the suicidal member to its grave. Such is the history of the fall of the leaf. "We have found that it is not an ac- cidental occurrence, arising simply from the vicissitudes of tempera- ture and the like, but a regular and vital process, which commences with the first formation of the organ, and is completed only when that is no longer useful ; and we cannot help admiring the wonder- ful provision that heals the wound even before it is absolutely made, and affords a covering from atmospheric changes before the part can be subjected to them." * Leaves fall by an articulation in most Exogenous plants, where the insertion usually occupies only a moderate part of the circumference of the stem, and especially in those with woody stems which continue to increase in diameter. When they are not cast off in autumn, therefore, the disruption inevitably takes place the next spring, or whenever the circumfer- * Dr. Inman, in Ilenfrey's Botanical Gazette, Vol. 1. p. 61. 15* 174 THE LEAVES. ence further enlarges. But in most Endogenous plants, where the leaves are scarcely, if at all, articulated with the stem, which in- creases little in diameter subsequent to its early growth, they are not thrown off, but simply wither and decay ; their dead bases or petioles being often persistent for a long time. 311. The Death of the Leaf, however, in these and other cases, is still to be explained. Why have leaves such a temporary exist- ence ? Why in ordinary cases do they last only for a single year, or a single summer ? An answer to this question is to be found in the anatomical structure of the leaf, and the nature and amount of the fluid which it receives and exhales. The water continually absorbed by the roots dissolves, as it percolates the soil, a small portion of earthy matter. In limestone districts especially, it takes up a sensible quantity of carbonate and sulphate of lime, and be- comes hard. It likewise dissolves a smaller proportion of silex, magnesia, potash, &c. A part of this mineral matter (44, 93) is at once deposited in the woody tissue of the stem ; but a larger por- tion is carried into the leaves, where, as the water is exhaled pure, all this earthy substance, not being volatile, must be left be- hind to incrust the delicate cells of the parenchyma, much as the vessels in which water is boiled for culinary purposes are in time incrusted with an earthy deposit. Tins earthy incrustation, in con- nection with the deposition of organic solidified matter, must grad- ually choke the tissue of the leaf, and finally unfit it for the per- formance of its offices. Hence the fresh leaves most actively fulfil their functions in spring and early summer ; but languish towards autumn, and erelong inevitably perish. Hence, although the roots and branches may be permanent, the necessity that the leaves should be annually renewed. But the former are, in fact, annually renewed likewise ; and life abandons the annual layers of wood and bark almost as soon as it does the leaves they supply (224, 231), and for similar reasons ; although their situation is such that they become part of a permanent structure, and serve to convey the sap, even when no longer endowed with vitality. 312. The general correctness of this view may be tested by direct microscopical observation. In Fig. 223, 224, some superficial paren- chyma thus obstructed by long use is represented ; and similar illustrations may be obtained from ordinary leaves. That this deposit consists in great part of earthy matter, is shown by care- fully burning away the organic materials of an autumnal leaf over EXHALATION AND THE RISE OF THE SAP. 175 a lamp, and examining the ashes by the microscope ; which will be found very perfectly to exhibit the form of the cells. The ashes which remain when a leaf or other vegetable substance is burned in the open air, represent the earthy materials which it has accu- mulated. A vernal leaf leaves only a small quantity of ashes ; an autumnal leaf yields a very large proportion, — from ten to thirty times as much as the wood of the same species ; although the leaves contain the deposit of a single season only, while the heart-wood is loaded with the accumulations of successive years.* 313. Exhalation from the Leaves. The quantity of water exhaled from the leaves during active vegetation is very great. In one of the well-known experiments of Hales, a Sunflower tliree and a half feet high, with a surface of 5,616 square inches exposed to the air, was found to perspire at the rate of twenty to thirty ounces avoirdu- pois every twelve hours, or seventeen times more than a man. A Vine, with twelve square feet of foliage, exhaled at the rate of five or six ounces a day ; and a seedling Apple-tree, with eleven square feet of foliage, lost nine ounces a day. The amount varies with the degree of warmth and dryness of the air, and of exposure to light ; and is also very different in different species, some exhaling more copiously even than the Sunflower. But when we consider the vast perspiring surface presented by a large tree in full leaf, it is evident that the quantity of watery vapor it exhales must be immense. This exhalation is dependent on the capacity of the air for moisture at the time, and upon the presence of the sun ; often it is scarcely perceptible during the night. The Sunflower, in the experiment of Hales, lost only three ounces in a warm, dry night, and underwent no diminution during a dewy night. 314. Rise of the Sap. Now this exhalation by the leaves requires a corresponding absorption by the roots. The one is the measure of the other. If the leaves exhale more in a given time than the roots can restore by absorption from the soil, the foliage droops ; as we see in a hot and dry summer afternoon, when the drain by * The dried leaves of the Elm contain more than eleven per cent of ashes, while the wood contains less than two per cent ; those of the Willow, more than eight per cent, while the wood has only 0.45 ; those of the Beech, 6.6$, the wood only 0.36 ; those of the (European) Oak, 4.05, the wood only 0.21 ; those of the Pitch-Pine, 3.15, the wood only 0.25 per cent. Hence the decaying foliage in our forests restores to the soil a large proportion of the inorganic matter which the trees from year to year take from it. 176 THE LEAVES. exhalation is very great, while a further supply of moisture can hardly be extorted from the parched soil ; — as we observe also in a leafy plant newly transplanted, where the injured rootlets are not immediately in a fit condition for absorption. Ordinarily, how- ever, exhalation by the leaves and absorption by the roots are in direct ratio to each other, and the loss sustained by the leaves is immediately restored (by endosmosis, 40) through the ascent of the sap from the branches, the latter being constantly supplied by the stem ; so that, during active vegetation, the sap ascends from the remotest rootlets to the highest leaves, at a rate corresponding to the amount of exhalation. The action of the leaves is, therefore, the principal mechanical cause of the ascent of the sap. This is well illustrated when a graft has a different time of leafing from that of the stock upon which it is made to grow, the graft wholly regulating the season or temperature at which the sap is put in motion, and controlling the habits of the original stock. Also by introducing the branches of a tree into a conservatory during winter ; when, as their buds expand, the sap in the trunk without is set unseasonably into motion to supply the demand. 315. During the summer's vegetation, Avhile the sap is consumed or exhaled almost as fast as it enters the plant, no considerable ac- cumulation can take place : but in autumn, when the leaves perish, the rootlets, buried in the soil beyond the influence of the cold, Avhich checks all vegetation above ground, continue for a time slowly to absorb the fluid presented to them. Thus the trunks of many trees are at this season gorged with sap, which will flow from in- cisions made into the wood. This sap undergoes a gradual change during the winter, and deposits its solid matter in the cells of the wood. The absorption recommences in the spring, before new leaves are expanded to consume the fluid ; chemical changes take place ; the soluble matters in the tissue of the stem are redissolved, and the trunk is consequently again gorged with sap, which will flow, or bleed, when wounded. But when the leaves resume their functions, or when flowers are developed before the leaves appear, as in many forest-trees, this stock of rich sap is rapidly consumed, and the sap will no longer flow from an incision. It is not, there- fore, at the period when the trunk is most gorged with sap, in spring and autumn, but when least so, during summer, that the sap is prob- ably most rapidly ascending. PHYSIOLOGY OF VEGETATION. 177 CHAPTER VI. OF THE FOOD AND NUTRITION OF PLANTS. Sect. I. The General Physiology of Vegetation. 316. The Organs of Vegetation or Nutrition (those by which plants grow and form their various products) having now been con- sidered, both as to their structure and to some extent as to their action, Ave are prepared to take a comprehensive survey of the general results of vegetation ; to inquire into the elementary com- position of plants, the nature of the food by which they are nour- ished, the sources from which this food is derived, and the transfor- mations it undergoes in their system. It is in vegetable digestion, or, to use a better term, in assimilation, that the essential nature of vegetation is to be sought, since it is in this process alone that min- eral, unorganized matter is converted into the tissue of plants and other forms of organized matter (1, 12-16). From this point of view, therefore, the reciprocal relations and influences of the min- eral, vegetable, and animal kingdoms may be most advantageously contemplated, and the office of plants in the general economy of the world best understood. This portion of general physiology is inti- mately connected with chemistry, and some knowledge of that sci- ence is requisite for understanding it. We are here restricted to the bare statement of the leading facts which are thought to be established, and the more important deductions which may be drawn from them. 317. While the organs of vegetation have been considered ana- tomically and morphologically, or in view of their structure and development, still the leading points of their physiology, or connected action in the life and growth of the plant, have from time to time been explained or assumed. 318. The functions of nutrition, which, in the higher animals, comprise a variety of distinct processes, are reduced to the greatest degree of simplicity in vegetables. Imbibition, assimilation, and growth essentially include the whole. 319. Plants absorb their food, entirely in a liquid or gaseous form, by imbibition, according to the law of endosmosis (40), through the 178 THE FOOD AND NUTRITION OF PLANTS. walls of the cells that form the surface, principally those of the newest roots and their fibrils (133). The fluid absorbed by the roots, mingled in the cells with some previously assimilated matter they contain in solution (26, 79), is diffused by exosmosis and endos- mosis from cell to cell, rising principally in the wood (224, 230) ; and is attracted into the leaves (or to other parts of the surface of the plant exposed to the air and light) by the exhalation which takes place from them (314), and the consequent inspissation of the sap. Here, exposed to the light of the sun, the crude sap is assimi- lated, or converted into organizable matter (79) ; and, thus prepared to form vegetable tissue or any organic product, the elaborated fluid is attracted into growing parts by endosmosis, in consequence of its consumption and condensation there, or is diffused through the newer tissues. There is no movement in plants of the nature of the cir- culation in animals. Even in the so-called vessels of the latex there is merely a mechanical flow from the turgid tubes towards the place where the liquid is escaping when wounded, or from a part placed under increased pressure (63). The only circulation, or directly vital movement of fluid, in vegetable tissue, is the cyclosis, or the system of currents in the layer of protoplasm in young and active cells (36) : this movement is confined to the individual cell, and can have no influence in the transference of the sap from cell to cell. Respiration is likewise a function of animals alone. What is generally so called in vegetables is connected with assimilation, and is of entirely different physiological significance, as will pres- ently be shown. None of the secretions of plants appeal', like many of those of animals, to play any part, at least any essential part, in nutrition. Many, if not all of them, are purely chemical transformations of the general assimilated products of plants, — are excretions rather than secretions (88 - 90). 320. The appropriation of assimilated matter in vegetable growth, and the production and multiplication of cells, which make up the fabric of the plant, have already been treated of (25-34). We have now mainly to consider what the food of plants is, whence it is derived, and how it is elaborated. THEIR ELEMENTARY CONSTITUENTS. 179 Sect. II. The Food and the Elementary Composition of Plants. 321. The Food and the elementary composition of plants stand in a necessary relation to each other. Since it is not to be sup- posed that plants possess the power of creating any simple element, whatever they consist of must have been derived from without. Their composition indicates their food, and vice versa. If we have learned the chemical composition of a vegetable, and also what it gives back to the soil and the air, Ave know consequently what it must have derived from without, that is, its food. Or, if we have ascertained Avhat the plant takes from the soil and air, and what it returns to them, we have learned its chemical composition, namely, the difference between these two. And when we compare the na- ture and condition of the materials which the plant takes from the soil and the air with what it- gives back to them, we may form a correct notion of the influence of vegetation upon the mineral king- dom. By considering the materials of which plants are composed, we may learn what their food must necessarily contain. 322. The Constituents Of Plants are of two kinds ; the earthy or in- organic, and the organic. It has been stated (93) that various earthy matters, dissolved by the water which the roots absorb, are drawn into the plant, and at length deposited in the wood, leaves, &c. These form the ashes which are left on burning a leaf or a piece of wood. Although these mineral matters are often turned to account by the plant, and some of them are necessary in the formation of certain products, (as the silex which gives needful firmness to the stalk of Wheat, and the phosphates which are found in the grain,) yet none of them are essential to simple vegetation, which may, to a certain extent, proceed without them. These materials, the presence of which is in some sort accidental, although for certain purposes essential, are distinguished as the earthy, or mineral, or inorganic constituents of plants. This class may be left entirely out of view for the present. But the analysis of any newly formed vegetable tissue, or of any part of the plant, such as a piece of Avood, after the incrusting mineral matter has been chemically removed, invariably yields but three or four ele- ments. These, which are indispensable to vegetation, and make up at least from eighty-eight to ninety-nine per cent of every vege- 180 THE FOOD AND NUTRITION OF PLANTS. table substance, are termed the universal, organic constituents of plants. They are Carbon, Hydrogen, Oxygen, and Nitrogen (10, 27). The proper vegetable structure, that is, the tissue itself, consists of only three of these elements, namely, carbon, hydrogen, and oxygen ; while the fourth, nitrogen, is an essential constituent of the protoplasm, which plays so important a part in the formation of the cells and is an element of one class of vegetable products. 323. The Organic Constituents. These four elements must be fur- nished by the food upon which the vegetable lives ; — they must be drawn from the soil and the air ; in some cases, doubtless, from the latter source, as in Epiphytes, or Air-plants (149), but gener- ally and principally by absorption through the roots. The plant's nourishment is wholly received either in the gaseous or the liquid form ; for the leaves can imbibe air or vapor only, and the roots are incapable of taking in particles of solid matter, however minutely di- vided (40, 133). 324. In whatever mode imbibed,- evidently the main vehicle of the plant's nourishment is water, which as a liquid or as vapor is continually in contact with its roots, and in the state of vapor always surrounds its leaves. We have seen how copiously water is taken up by the growing plant, and have formed some general idea of its amount by the quantity that is exhaled unconsumed by the leaves (313). But pure water, although indispensable, is insufficient for the nourishment of plants. It consists of oxygen and hydrogen ; and therefore may furnish, and doubtless does principally furnish, these two essential elements of the vegetable structure. But it can- not supply what it does not itself contain, namely, the carbon and nitrogen which the plant also requires. 325. Yet the question arises, whether the water which the plant actually imbibes contains in fact a quantity of these remaining elements. Though pure water cannot, may not rain-water supply the needful carbon and nitrogen ? It is evident that, if the water which in such large quantities rises through the plant, and is ex- haled from its leaves, contain even a very minute quantity of these ingredients, in such a form that they may be detained when the superfluous water is exhaled, this might furnish the whole organic food of the vegetable ; since the plant may condense and accumu- late the carbon and nitrogen, just as the extremely minute quantity of earthy matter which the water contains is in time largely accu- mulated in the leaves and wood. SOURCE OF THEIR ORGANIC CONSTITUENTS. 181 326. As respects the nitrogen, nearly seventy-nine per cent of the atmosphere consists of this gas in an uncombined or free state, that is, merely mingled with oxygen. And, being soluble to some extent in water, every rain-drop that falls through the air absorbs and brings to the ground a minute quantity of it, which is therefore necessarily introduced into the plant with the water which the roots imbibe. This accounts for the free nitrogen which is always pres- ent in plants. 327. The plant also receives nitrogen in the form of ammonia (or hartshorn), a compound of hydrogen and nitrogen, which is always produced when any animal and almost any vegetable sub- stance decays, and which, being very volatile, continually rises into the air from these and other sources. Besides, it appears to be formed in the atmosphere, through electrical action in thunder-storms (in the form of nitrate of ammonia). The extreme solubility of am- monia and all its compounds prevents its accumulation in the atmos- phere, from which it is greedily absorbed by aqueous vapor, and brought down to the ground by rain. That the roots actually ab- sorb it may be inferred from the familiar facts, that plants grow most luxuriantly when the soil is supplied with substances which yield much ammonia, such as animal manures ; and that ammonia may be detected in the juices of almost all plants. That the am- monia in the air, and the nitre almost everywhere formed in a fertile soil, and not the free nitrogen of the atmosphere, take the principal part in the formation of the protoplasm and other quaternary ele- ments of plants, is demonstrated by Boussingault T s experiments, showing that a seedling from which all nitrogen is excluded except the free nitrogen of the air, as it vegetates does not increase the amount of azotized matter it originally had in the seed, but dimin- ishes it.* Rain-water, therefore, contains the third element of vegetation, namely, nitrogen, both in a separate form and in that of ammonia, &c. 328. The source of the remaining constituent, carbon, is still to be sought. Of this element plants must require a copious supply, since it forms much the largest portion of their bulk. If the carbon of a leaf or of a piece of wood be obtained separate from the other organic elements, — which may be done by charring, that is, by heating it out of contact with the air, so as to drive off the oxygen, * Comptes Rendus, November 28, 1853, and Ann. Sci. Naturdles, ser. 4, Vol. 1 & 2 (1854) ; also Vol. 7 (1857), showing the part which nitre plays. 16 182 THE FOOD AND NUTRITION OF PLANTS. hydrogen, and carbon, — although a small part of the carbon is necessarily lost in the operation, yet what remains perfectly pre- serves the shape of the original body, even to that of its most delicate cells and vessels. With the exception of the ashes, this consists of carbon, or charcoal, amounting to from forty to sixty per cent, by weight, of the original material. Carbon is itself a solid, absolutely insoluble in water, and therefore incapable of as- sumption by the plant. The chief, if not the only, fluid compound of carbon which is naturally presented to the plant, is that of car- bonic acid gas, which consists of carbon united with oxygen. This gas makes up on the average one 2500th of the bulk of the at- mosphere ; from which it may be directly absorbed by the leaves. But, being freely soluble in water up to a certain point, it must also be earned down by the rain and imbibed by the roots. The car- bonic acid of the atmosphere is therefore the great source of carbon for vegetation. 329. It appears, then, that the atmosphere — considering water in the state of vapor to form a component part of it — contains all the essential materials for the growth of vegetables, and in the form best adapted to their use, namely, in the fluid state. It furnishes water, which is not only food itself, inasmuch as it supplies oxygen and hydrogen, but is likewise the vehicle of the others, conveying to the roots what it has gathered from the air, namely, the requisite supply of nitrogen, either as such or in the form of ammonia, and of carbon in the form of carbonic acid. 330. These essential elements, the whole proper food of plants, may he absorbed by the leaves directly from the air, in the state of gas or vapor. Doubtless most plants actually take in no small part of their food in this way. Drooping foliage may be revived by sprinkling with water, or by exposure to a moist atmosphere. A vigorous branch of the common Live-for-ever (Sedum Telephium), or of many similar plants, it is well known, will live and grow for a whole season when pinned to a dry and bare wall ; and the Epi- phytes, or Air-plants (149), as they are aptly called, must derive their whole sustenance immediately from the air ; for they have no connection with the ground. That leaves absorb carbonic acid directly from the air is readily shown (348). 331. But, as a general statement, it may be said that plants, al- though they derive their food from the air, receive it mainly through their roots. The aqueous vapor, condensed into rain or dew, and SOURCE OF THEIR ORGANIC CONSTITUENTS. 183 bringing with it to the ground a portion of carbonic acid, and of nitrogen or ammonia, &c, supplies the appropriate food of the plant to the rootlets (sometimes in a liquid, but also much of it in a gaseous form). Imbibed by these, it is conveyed through the stem and into the leaves, where the superfluous water is restored to the atmosphere by exhalation,* while the residue is converted into the proper nour- ishment and substance of the vegetable. 332. The atmosphere is therefore the great storehouse from which A^egetables derive their nourishment ; and it might be clearly shown that all the constituents of plants, excepting the small earthy portion that many can do without, have at some period formed a part of the atmosphere. The vegetable kingdom represents an amount of matter, which plants have withdrawn from the air, organ- ized, and confined for a time to the surface. 333. Does it therefore follow, that the soil merely serves as a foothold to plants, and that all vegetables obtain their whole nour- ishment directly from the atmosphere ? This must have been the case with the first plants that grew, when no vegetable or animal matter existed in the soil ; and no less so with the first vegetation that covers small volcanic islands raised in our own times from the sea, or the surface of lava thrown from ordinary volcanoes. No vegetable matter is brought to these perfectly sterile mineral soils, except the minute portion contained in the seeds wafted thither by winds or waves. And yet in time a vast quantity is produced, which is represented not only by the existing vegetation, but by the mould that the decay of previous generations has imparted to the soil. We arrive at the same result by the simple experiment of causing a * The water exhaled may be again absorbed by the roots, laden with a new supply of the other elements from the air, again exhaled, and so on ; as is beautifully illustrated by the cultivation of plants in closed Ward cases, where plants are seen to flourish for a long time with a very limited supply of water, every particle of which (except the small portion actually consumed by the plants) must pass repeatedly through this circulation. This vegetable micro- cosm well exhibits the actual relations of water, &c. to vegetation on a large scale in nature ; where the water is alternately and repeatedly raised by evapo- ration and recondensed to such extent that what actually falls in rain is esti- mated to be re-evaporated and rained down (on an average throughout the world) ten or fifteen times in the course of a year. In this way the atmosphere is repeatedly washed by the rain ; and those vapors ivashed out which else by their accumulation would prove injurious to men and animals, and conveyed to the roots of plants, which they are especially adapted to nourish. 184 THE FOOD AND NUTRITION OF PLANTS. seed of known weight to germinate on powdered flints, or on a soil which has been heated to redness, and watering it with rain-water alone. "When the young plant has attained all the development it is capable of under these circumstances, it will be found to weigh (after due allowance for the silex it may have taken up) perhaps fifty or one hundred times as much as the original seed. There can be no question as to the source of this vegetable matter in all these cases. The requisite materials exist in the air. Plants possess the peculiar faculty of drawing them from the air. The air must have furnished the whole. This conclusion is amply confirmed by a great variety of familiar facts ; such as the continued accumulation of vegetable mat- ter hi peat-bogs, and of mould in neglected fields, in old forests, and generally wherever vegetation is undisturbed. Since this rich mould, instead of diminishing, regularly increases with the age of the forest and the luxuriance of vegetation, the trees must have drawn from the air, not only the vast amount of carbon, &c. that is stored up in their trunks, but an additional quantity which is im- parted to the soil in the annual fall of leaves, &c. 334. Still it by no means follows that each plant draws all its nourishment directly from the air. This unquestionably happens in some of the special cases just mentioned ; with Air-plants, and with those that first vegetate on volcanic earth, bare rocks, naked walls, or pure sand. But it is particularly to be remarked, that only certain tribes of jdants will continue to live under such cir- cumstances, and that none of the vegetables most useful as food for man or the higher animals will thus thrive and come to matu- rity. In nature, the races of plants that will grow at the entire expense of the air, such as Lichens, Mosses, Ferns, and certain tribes of succulent Flowering plants, gradually form a soil of vege- table mould during their life, which they increase in their decay ; and the successive generations live more vigorously upon the in- heritance, being supported partly upon what they draw from the air, and partly upon the ancestral accumulation of vegetable mould. Thus, each generation may enrich the soil, even when consisting of plants that draw largely upon vegetable matter thus accumulated ; for these annually restore a portion by their dead leaves, &c, and when they die they may bequeath to the soil, not only all that they took from it, but all that they drew from the air. It is in this way that the lower tribes and so-called useless plants create a soil, which will in time support the higher plants, of immediate importance t^ SOURCE OF THEIR ORGANIC CONSTITUENTS. 185 man and the higher animals, but which could never grow and per- fect their fruit, if left, like their humble but indispensable predeces- sors, to derive an unaided subsistence directly from the inorganic world. While it is strictly true, therefore, that all the organic ele- ments have been originally derived from the air, it is not true that what is contained in almost any given plant, or in any one crop, is immediately drawn from this source. A part of it is thus supplied, but in proportions varying greatly in different species and under different circumstances. Undisturbed vegetation consequently tends always to enrich the soil. But in agriculture the crop is ordinarily removed from the land, and with it not only what it has taken from the earth, but also what it has drawn from the air ; and the soil is accordingly impoverished. Hence the farmer finds it necessary to follow the example of nature, and to restore to the land, in the form of manure, an amount substantially equivalent to what he takes away. 335. The mode in which vegetable mould is turned to account by growing plants has not yet been sufficiently investigated. Ac- cording to Liebig, the decaying vegetable matter is not employed until it has been resolved into its original inorganic elements, namely, into water, carbonic acid, ammonia, &c. ; which are imbibed by the roots both directly in the gaseous state, and when taken up by the water as it percolates through the soil.* Others suppose that a portion of the food which plants derive from decaying vegetable matter may consist of soluble, still organic compounds. The econ- omy of the greenless parasitic plants (152) is adduced in confirma- tion of this view : but these are nourished by the foster plant just as its own flowers are nourished. Decisive evidence to the point is furnished by Fungi, the greater part of which live upon decaying organic matter, and have not the power of forming organizable pro- * While it may be rightly said, that the proportion of carbonic acid in the atmosphere is too minute directly to supply ordinary vegetation, especially that of esculent plants, with sufficient carbon, this cannot be said of the air contained in the pores and crevices of the soil, at least in any fertile soil. This air in the soil contains a far larger proportion of carbonic acid than the atmos- phere above ; the excess being derived partly by direct absorption or by the action of rain, and in an enriched soil more largely from the decay of the mate- rials of former generations of plants. In a recently manured soil, the carbonic acid ordinarily amounts even to 10 or 20 per cent. See Boussingault and Lewy, in Ann. Sci. Nat. ser. 3, Vol. 19, p. 13. 16* 186 THE FOOD AND NUTRITION OF PLANTS. ducts from inorganic materials ; and there is reason to think, that some Phosnogamous plants (of which our Monotropa, or Indian Pipe is one) are nourished in this way. 336. The Earthy Constituents. The mineral substances which form the inorganic constituents of plants (322) are furnished by the soil, and are primarily derived from the slow disintegration and decom- position of the rocks and earths that compose it.* These are dis- solved, for the most part in very minute proportions, in the water which percolates the soil, (aided, as to the more insoluble earthy salts, by the carbonic acid which this water contains,) and with this water are taken up by the roots. However minute their proportion in the water which the roots imbibe, the plant concentrates and accumulates them, by the exhalation of the water from the leaves, until they amount to an appreciable quantity, often to a pretty large percentage, of the solid matter of the vegetable. As might be ex- pected (312), the leaves contain a much larger amount of ashes, or earthy matter, than the wood, and herbaceous plants more than trees, in proportion to their weight when dry.f 337. The ashes left after combustion are mostly composed of the " alkaline chlorides, with the bases of potash and soda, earthy and metallic phosphates, caustic or carbonate of lime and magnesia, silica, and oxides of iron and of manganese. Several other sub- stances are also met with there, but in quantities so small that they may be neglected." Different species growing in the same soil appear to take in some portion of all such materials as are natu- * According to Licbig, the quantity of potash contained in a layer of soil formed by the disintegration of 40,000 square feet of the following rocks, &c, to the depth of twenty inches, is as follows. This quantity of Felspar (a large component of granite, &c.) contains . . . 1,152,000 lbs. Clinkstone, ..... from 200,000 to 400,000 " Basalt, ..... " 47,500 " 75,000 " Clay-slate, ....." 100,000 " 200,000 " Loam, . . . . . . " 87,000 " 300,000 " The silex yielded to the soil by the gradual decomposition of granite and other rocks is in the form of a silicate of potash or other alkali, which, though insoluble in pure water, is slowly acted upon and dissolved by the united action of water and carbonic acid, or more largely by water impregnated with carbon- ate of potash, which is abundantly liberated during the natural decomposition of these rocks. t The subjoined results, selected from Boussingault, exhibit in a tabular form the relative quantities of organic and inorganic constituents in several kinds of THEIR EARTHY CONSTITUENTS. 187 rally presented to them in solution, but not, however, in the same proportions, nor in proportion to the relative solubility of these several substances ; while, on the other hand, the same species in different localities, and also each of its particular parts or organs, contains, or tends to contain, the same mineral constituents in nearly the same proportion. One base, however, is often substituted for another, equivalent for equivalent, as magnesia for lime, soda for potash. The roots, therefore, appear to have a certain power of selection in respect to these mineral materials. Nor is it a valid objection to this view, that they absorb poisons which destroy them. These are either organic products, such as opium ; or else are cor- rosive substances, such as sulphate of copper, which disorganize the rootlets. For mutilated roots or stems absorb all dissolved materials of the proper density that are presented to them, not only in much larger quantity (so long as the cut is fresh) than do uninjured root- lets, but almost indifferently, and in the same proportion that they absorb the water they are dissolved in. 338. In the ashes, only the salts which resist the action of heat, such as the phosphates, sulphates, and hydrochlorates, are in the state in which they existed in the plant itself. A great part of the bases were combined with organic acids, formed in the plant, and most largely with the oxalic (86) : these compounds are by incinera- tion, or by exposure to the air, principally converted into carbonates. 339. It being indispensable to its well-being that a plant should find in the soil such mineral matters as are necessary to its growth, we perceive why various species Avill only flourish in particular soils or situations ; why plants which take up common salt, &c. are re- stricted to the sea-shore and to the vicinity of salt-springs ; why herbage, compared, in several cases, with the root or grain. The water was previously driven off by thorough drying. Carbon, Hydrogen, Oxygen, Nitrogen, Ashes, H °| -' Jl p. aj c3 ho s f-s <« 3 °^ o o PS Pi o o o fk 44.80 5.10 30.50 2.30 17.30 CI o o Peas. Clover-hay. Be a u % si 48.48 5.41 38.79 0.35 6.97 100.00 1 46.10 5.80 4340 2.27 2.43 100.00 38.10J 42.75 5.10 5.77 30.80 43.58 4.50 1.66 21.50 6.24 43.72 6.00 44.88 1.50 3.90 100.00 45.80 5.00 35.57 2.31 11.32 100.00 46.06 6.09 40.53 4.18 3.14 47.53 4.69 37.96 2.06 7.76 100.00 100.00 100.00 100.00 100.00 188 THE FOOD AND NUTRITION OF PLANTS. numerous weeds which grow chiefly around dwellings, and follow the footsteps of man and the domestic animals, flourish only in a soil abounding in nitrates (their ashes containing a notable quantity either of nitrate of potash or of lime) ; why the Vine requires alka- line manures, to replace the large amount of tartrate of potash which the grapes contain ; and why Pines and Firs, the ashes of which contain very little alkali, will thrive in thin or sterile soils, while the Beech, Maple, Elm, &c., abounding with potash, are only found in strong and fertile land. 340. Where vegetation is undisturbed by man, all these needful earthy materials, which are drawn from the soil during the growth of the herbage or forest, are in time restored to it by its decay, in an equally soluble form, along with organic matter which the vegetation has formed from the air. But in cultivation, the prod- uce is carried away, and with it the materials which have been slowly yielded by the soil. " A medium crop of Wheat takes from one acre of ground about 12 pounds, a crop of Beans about 20 pounds, and a crop of Beets about 11 pounds, of phosphoric acid, besides a very large quantity of potash and soda. It is obvious that such a process tends continually to exhaust arable land of the mineral substances useful to vegetation which it contains, and that a time must come, when, without supplies of such mineral matters, the land Avould become unproductive from their abstraction In the neighborhood of large and populous towns, for instance, where the interest of the farmer and market-gardener is to send the largest possible quantity of produce to market, consuming the least possible quantity on the spot, the want of saline principles in the soil would very soon be felt, were it not that for every wagon-load of greens and carrots, fruit and potatoes, corn and straw, that finds its way into the city, a wagon-load of dung, containing each and every one of these principles locked up in the several crops, is returned to the land, and proves enough, and often more than enough, to replace all that has been carried away from it." * The loss must either be made up by such equivalent return, or the land must lie fallow from * Boussingault, Eeonomie Rurale : from the Engl. Trans., p. 493. Further : " It may be inferred that, in the most frequent case, namely, that of arable lands not sufficiently rich to do without manure, there can be no continuous [independent] cultivation without annexation of meadow; in other words, one part of the farm must yield crops without consuming manure, so that this may replace the alkaline and earthy salts which are constantly withdrawn by sue- THEIR EARTHY CONSTITUENTS. 189 time to time until these soluble substances are restored by further disintegration of the materials of the soil : or meanwhile the more exhausting crops may be alternated with those that take least from the soil and most from the air ; or with one which, like clover, although it takes up 77 pounds of alkali per acre, may be consumed on the field, so as to restore most of this alkali in the manure for the succeeding crop. 341. It has been asserted that the advantage of preceding a wheat crop by one of Leguminous plants (such as Peas, Clover, Lucerne, &c), or of roots or tubers, is owing to the fact, that these leave the phosphates, &c. nearly untouched for the wheat which is to follow, and which largely abstracts them. The results of Bous- singault's experiments and analyses show that these products are far from having the deficiency of phosphates which was alleged. " For example, beans and haricots take 20 and 13.7 pounds of phosphoric acid from every acre of land ; potatoes and beet-root take 11 and 12.8 pounds of that acid, exactly what is found in a crop of wheat. Trefoil is equally rich in phosphates with the sheaves of corn that have gone before it." * His further re- cessive harvests from another part. Lands enriched by rivers alone permit of a total and continued export of their produce without exhaustion. Such are the fields fertilized by the inundations of the Nile ; and it is difficult to form an idea of the prodigious quantities of phosphoric acid, magnesia, and potash, which, in a succession of ages, have passed out of Egypt with her incessant exports of corn." — p. 503. * Boussingault, I. c, p. 497. — Subjoined is a table, from the same work, of the percentage of Mineral Substances taken up from the soil by various plants grown at Bechelbronn. Substances which yielded the Ashes. Acids. 1 o — 2.7 a j 1.8 0) to si a 5.4 o Pm 51.5 c3 ■3 o TO (3 53 a z o a ffl 3 o - n o „ is u "5 o .a u 8 § si Of s 3 A p. o si 11.3 Potatoes, 13.4; 7.1 traces 5.6 0.5 0.7 Man gel-Wurzel, 16.1 1 1.6 6.1 5.2 7.0 4.4 39.0 6.0 8.0 2.5 4.2 Turnips, 14.0 10.9 6.0 2.9 10.9 4.3 33.7 4.1 6.4 1.2 5.5 Potato-tops, 11.0. 22 10.8 1.6 2.3 1.8 44.5 traces 13 5.2 7.6 Wheat, 0.0 1.0 47.0 traces 2.9 15.9 29.5 traces 1.3 0.0 2.4 Wheat-straw, 00 1.0 3.1 0.6 8.5 5.0 9.2 0.3 67.6 1.0 3.7 Oats, 1.7 1.0 14.9 0.5 3.7 7.7 12.9 0.0 53.3 1.3 3.0 Oat-straw, 3.2 4.1 3.0 4.7 8.3 2.8 24.5 44 40.0 2.1 29 Clover, 25.0 2.5 6.3 2.6 246 6.3 266 0.5 5.3 0.3 00 Peas, 0.5 4.7 30.1 1.1 10.1 11.9 35.3 2.5 1.5 traces 2.3 French beans, 3.3 1.3 26.8 0.1 5.8 11.5 49.1 00 1.0 traces 1.1 Horse beans, 10 1.6 134.2 0.7 5.1 i 8.6i45.2 00 05 traces 3 1 190 THE FOOD AND NUTRITION OF PLANTS. searches seem to show that these crops exhaust the soil less than the cereal grains, in part at least, on account of the large quantity of organic matter, rich in nitrogen, which they leave to be incor- porated with the soil. The theory of rotation in crops, founded by De Candolle on the assumption that excretions from the roots of a plant accumulate in the soil until in time they become injurious to that crop, but furnish appropriate food for a different species, is entirely abandoned as an explanation ; and even the fact that such excretions are formed, at least to any considerable extent, is not made out. That they could accumulate and remain in the soil without undergoing decomposition is apparently impossible. Sect. III. Assimilation, or Vegetable Digestion, and its Results. 342. We have reached the conclusion, that the universal food of plants is rain-water, which has absorbed some carbonic acid gas and nitrogen (partly in the form of ammonia or of other compounds) from the air, or dissolved them from the remains of former vegeta- tion in the soil, whence it has also taken up a variable (yet more or less essential) quantity of earthy matter. 343. This fluid, imbibed by the roots, and carried upwards through the stem, receives the name of sap or crude sap (79). Upon its introduction into the plant, this is at once mingled with some elaborated sap or soluble organized matter it meets with ; thus becoming sweet in the Maple, &c, and acquiring different sensible properties in different species. This latter is already elab- orated food, and may therefore be immediately employed in vegeta- ble growth. But the crude sap itself is merely raw material, unor- ganized or mineral matter, as yet incapable of forming a part of the living structure. Its conversion into organized matter constitutes the process of 344. Assimilation, or what, from an analogy with animal life, is usually termed Vegetable Digestion. To undergo this important change, the crude sap is attracted into the leaves, or other green parts of the plant, which constitute the apparatus of assimilation, where it is exposed to the light of the sun, under which influence alone can this change be effected. Under the influence of solar light, the fabric is itself constructed, and the chlorophyll, or green ASSIMILATION*. 191 matter of plants, upon which, or in connection with winch, the light exerts its wonderful action, is first developed. When plants are made to grow in insufficient light, as when potatoes throw out shoots in cellars, this green matter is not formed. When light is with- drawn, it is soon decomposed ; as we see when Celery is blanched by heaping the soil around its stems. So, also, the naturally green- less leaves of plants parasitic upon the roots or stems of other species (152) have no direct power of assimilation, but feed upon and grow at the expense of already assimilated matter. But all green parts, such as the cellular outer bark of most herbs, act upon the sap in the same manner as leaves, even supplying their places in plants which produce few or no leaves, as in the Cactus, &c. Under the influence of light, an essential preliminary step in vegetable digestion is accomplished, namely, the concentration of the crude sap by the evaporation or exhalation of the now superfluous water, the mechan- ism and consequences of which have already been considered (313). 345. We have now to consider the further agency of light in vege- table digestion itself, namely, its action in the leaf upon the concen- trated sap. Here it accomplishes two unparalleled results, which es- sentially characterize vegetation, and upon which all organized exist- ence absolutely depends (1, 1G). These are, — 1st. The chemical decomposition of one or more of the substances in the sap which contain oxygen gas, and the liberation of this oxygen at the ordi- nary temperature of the air. The chemist can liberate oxygen gas from its compounds only by powerful reagents, or by great heat. 2d. The transformation of this mineral, inorganic food into organic matter, — the organized substance of living plants, and consequently of animals. These two operations, although separately stated, are in fact but different aspects of one great process. We contemplate the first, when we consider what the plant gives back to the air; the second, when we inquire what it retains as the materials of its own growth. The concentrated sap is decomposed ; the portion not required in the growth of the plant is returned to the air ; and the remaining elements are at the same time rearranged, so as to form peculiar organic products. 346. The principal material given back to the air, in this pro- cess, is oxygen gas,* that element of our atmosphere which alone * A small proportion of nitrogen gas is likewise almost constantly exhaled from the leaves ; but this appears to come from the nitrogen which the water 192 THE FOOD AND NUTRITION OF PLANTS. renders it fit for the breathing and life of animals. That the foliage of plants in sunshine is continually yielding oxygen gas to the sur- rounding air has been familiarly known since the days of Ingenhouss and Priestley, and may at any moment be verified by simple experi- ment. The readiest way is, to expose a few freshly gathered leaves to the sunshine in a glass vessel filled with water, and to collect the air-bubbles which presently arise while the light falls upon them, but which cease to appear when placed in shadow. This air, when examined, proves to be free oxygen gas. In nature, diffused day- light produces this effect ; but in our experiments, direct sunshine is generally necessary to show it. What is the source of this oxygen gas, which is given up to the air just in proportion to the vigor of assimilation in the leafy plant, or, in other words, to the consumption of crude sap ? 347. This will be manifest on comparing the materials with the general products of vegetation, — what the plant takes as its food, with what it makes of it, in growth. Suppose the plant is assimi- lating its food immediately into its fabric, viz. into Cellulose, or the substance of which its tissue consists (27). This matter, when in a pure state, and free from incrusting materials, has a perfectly uni- form composition in all plants. It is composed of carbon, hydrogen, and oxygen, the latter two existing in the same proportions as in water.* It may therefore be said to consist of carbon and the ele- ments of water. These materials are necessarily furnished by the plant's food. The mineral food of the plant, from which its fabric is made (329), is carbonic acid and water. If this be decomposed in vegetation, and the carbonic acid give up its oxygen, carbon and the elements of water remain, — the very composition of cellulose or vegetable tissue. Doubtless, then, the oxygen which is rendered to the air in vegetation comes from the carbonic acid which the plant took from the air (328). 348. This view may be confirmed by direct experiment. We imbibed by the roots had absorbed from the air (326), and which passes off un- altered from the leaves when this water is evaporated, or from nitrogen in the air which the rootlets directly absorb. In the course of vegetation, no more nitrogen is given out than what is thus taken in, and probably not so much. So that the exhalation of nitrogen may be left out of the general view of the changes which are brought about in vegetation. * Cellulose is chemically composed of 12 equivalents of Carbon, 10 of Hy- drogen, and 10 of Oxygen, viz. C12, H10, O10. ASSIMILATION. 193 have seen that many plants must, and all may, imbibe the whole or a part of their food directly from the air into their leaves (330). All leafy plants evidently obtain a part of their carbonic acid in this way. It is accordingly found, that when a current of carbonic acid is made slowly to traverse a glass globe containing a leafy plant ex- posed to full sunshine, some carbonic acid disappears, and an equal bulk of oxygen gas supplies its place. Now, since carbonic acid gas contains just its own bulk of oxygen, it is evident that what has thus been decomposed in the leaves has returned all its oxygen to the air. Plants take carbonic acid from the atmosphere, therefore (directly or indirectly) ; they retain its carbon ; they give back its oxygen.* 349. But cellulose, being the final, insoluble product of vegetation appropriated as tissue, can hardly be directly formed in the first in- stance. The substances from which it must originate, and which actually abound in the elaborated sap, are Dextrine or Vegetable Mucilage (79, 83), Sugar (80), &c The first of these is probably directly produced in assimilation. Its chemical composition is the same as that of pure cellulose : it consists, not only of the same three elements, but of the same elements in exactly the same pro- portion. Dextrine, vegetable mucilage, &c. are the primary, as yet unappropriated materials of vegetable tissue, or unsolidified cellu- lose, and their production from the crude sap is attended with the evolution of the oxygen which was contained in the carbonic acid of the plant's food, as already stated. Nor would the result in any respect be altered if Starch were directly produced. This substance is merely dextrine, which, instead of being immediately appropriated in growth, is condensed into solid grains, and in that compact and * At least, the result is as if the oxygen exhaled were all thus detached from the carhon of the carbonic acid. Just this amount is liberated, and the facts obviously point to the carbonic acid as its real source. But, on the other hand, it appears unlikely that a substance which holds oxygen with such strong affinity as carbon should yield the whole of it under these circumstances : and water is certainly decomposed, with the evolution of oxygen, in the formation of a class of vegetable products soon to be mentioned ; besides, Edwards and Colin have shown that water is directly decomposed during germination. Still, as no one supposes that the residue after the liberation of oxygen is carbon and water, but only the three elements in the proportions which would constitute them, it amounts to nearly the same thing whether we say that the oxygen of the carbonic acid, or an amount of oxygen equivalent to that of the carbonic acid, derived partly from it and partly from the water, is liberated in such cases. 17 194 THE FOOD AND NUTRITION OF PLANTS. temporarily insoluble form accumulated as the ready prepared ma- terials of future growth (82). Notwithstanding the difference in their properties and chemical reactions, these and other general ternary products (79) are strictly isomeric ; that is, they consist of the same elements, combined in the same proportions ; and physi- ologically they are merely different states of one and the same thing. Dextrine is the most soluble state, and is probably that originally formed in assimilation in the foliage : starch, amyloid (83), &c. are temporarily solidified states ; and cellulose is the ultimate and usu- ally permanent insoluble condition. Accordingly, whenever the ma- terials of growth are supplied from accumulations of nourishment, as especially from the seed in germination (123-125), from fleshy roots (145), rootstocks, tubers, &c. (188-194), the starch or its equivalent is dissolved in the sap, being spontaneously reconverted into dextrine and sugar, and attracted in a liquid state into the growing parts, where, transformed into cellulose, it becomes a por- tion of the permanent vegetable fabric. 350. If, however, we suppose sugar to be a direct product of the assimilation of carbonic acid and water, the amount of oxygen gas exhaled will be just the same as before. For this has the same elementary composition as dextrine, starch, and cellulose, with the addition of one or two equivalents of water according to the kind.* And when formed as a transformation of dextrine, then the latter has only to appropriate some water. In the origination of all these products, therefore, the same quantity of carbonic acid is consumed, and all its oxygen restored to the air.f It is more and more evident, * The formula for cane-sugar is Ci2, Hn, On ; for grape-sugar, Ci2, Hi2, O12. t Since all these neutral ternary substances are identical, or nearly so, in ele- mentary composition, and since, with the same amount of carbon, derived from the decomposition of carbonic acid, the plant can form them all, it will no longer appear surprising that they should be so readily convertible into each other in the living plant, and even in the hands of the chemist. But the chemistry of organic nature exceeds the resources of science, and constantly produces trans- formations which the chemist in his laboratory is unable to effect. The latter can change starch into dextrine, and dextrine into sugar ; but he cannot reverse the process, and convert sugar into dextrine, or dextrine into starch. In the plant, however, all these various transformations are continually taking place. Thus, the starch deposited in the seed of the Sugar-cane, Indian Corn, &c. is changed into sugar in germination ; and the sugar which fills the tissue of the stem at the time of flowering is rapidly carried into the flowers, where a portion is transformed into starch and again deposited in the newly-formed seeds. And ASSIMILATION. 195 therefore, that, by just so much as plants grow, they take carbonic acid from the air, they retain its carbon, and return its oxygen. 351. In the production of that modification of cellulose called Lignine (42), which abounds in wood (if this be really a simple product, and not a mixture), not only must a larger amount of car- bonic acid be decomposed, but a small portion of water also, Avith the liberation of its oxygen. For the composition attributed to it shows that it contains less oxygen than would suffice to convert its hydrogen into water.* 352. The whole class of fatty substances, including the Oils, Wax, Chlorophyll (84, 88, 92), &c, contain, some of them no oxygen at all (such as caoutchouc and Pine-oil), and all of them less oxygen than is requisite to convert their hydrogen into water. In their direct formation, if this be supposed, not only all the oxygen of the carbonic acid has been given out, but also a portion belonging to the water. If formed by a further deoxidation of neutral ternary pro- ducts, the same result is attained as respects the liberation of oxy- gen gas, but by two or more steps instead of one. The Resins, doubtless, are not direct vegetable products, but originate from the alternation and partial oxidation of the essential oils. Balsams, which exude from the bark of certain plants, are natural solutions of resins in their essential oils, as rosin, or Pine-resin, in the oil of tur- pentine. 353. An opposite class, the Vegetable Acids (8G), contain more oxygen than is necessary for the conversion of their hydrogen into water, but less than the- amount which exists in carbonic acid and water. Indeed, the most general vegetable acid, the oxalic (which may be formed artificially by the action of nitric acid on starch), has no hydrogen, except in the atom of water that is connected with it. Acids are sometimes formed in the leaves, as in the Sorrel, the although the chemist is unable to transform starch, sugar, &c. into cellulose, yet he readily effects the opposite change, by reconverting woody fibre, &c. (under the influence of sulphuric acid) into dextrine and sugar. The plant does the same thing in the ripening of fruits, during which a portion of tissue is often transformed into sugar. Starch-grains and cellulose can never be formed arti- ficially, because they are not merely organizable matter, but have an organic structure. * According to Payen, lignine, separated as much as possible from cellulose, consists of Carbon 53.8, Hydrogen 6.0, and Oxygen 40.2 per cent, = C35, H21, O so . 196 THE FOOD AND NUTRITION OF PLANTS. Grape-vine, &c, but usually in the fruit. If produced directly from the sap, as they may be in acid leaves, only a part of the oxygen in the carbonic acid which contributes to their formation would be ex- haled. But if formed from sugar, or any other of the general pro- ducts of the proper juice, the absorption of a portion of oxygen from the air would be required for the conversion ; and this absorption takes place (at least in some cases) when fruits acquire their acidity. Even their formation by the plant, therefore, is attended by the lib- eration of oxygen gas, though in less quantity than in ordinary vege- tation. 354. There is still another class of vegetable products of uni- versal occurrence, and, although comparatively small in quantity in plants, yet of as high importance as those which constitute their permanent fabric ; namely, the neutral quaternary organic com- pounds, of which nitrogen is a constituent (79). These, also, are mutually convertible bodies, related to each other as dextrine and sugar are to starch and cellulose, and playing the same part in the animal economy that the neutral ternary products do in the vege- table, i. e. forming the fabric of animals. The basis or type of these azotized products has received the name of Proteine (27) : hence they are sometimes collectively called proteine compounds. In their production from the plant's food, the ammonia, or other azotized matter it contains, plays an essential part ; and oxygen gas is restored to the air from the decomposition of all the carbonic acid concerned and of a part of the water.* 855. In living cells the proteine forms the protoplasm, or vitally active lining, which may be said to give origin to the vegetable structure, since the cellulose is deposited under its influence to form the permanent walls or fabric of the cells, as has already been explained (26-3G). When the cells have completed their growth * The chemical changes have been tabulated thus : — The materials : From which are formed the product : C. H. N. 0. C. H. N. 0. 74 of Water, 74 74 1 of Proteine, 48 36 6 14 94 of Carbonic acid, 94 188 4 of Cellulose, 48 40 40 2 of Carbonate of 212 of Oxygen lib- ammonia, 2 2 6 4 crated, 212 96 76 6 266 96 76 6 266 Besides, proteine cither contains or is naturally combined with a small quan- tity of sulphur and phosphorus (10). ASSIMILATION. 197 and transformation, the protoplasm abandons them, the portion which is not decomposed being constantly attracted onwards into forming and growing parts, where it incites new development. For this azotized matter has the remarkable peculiarity of inducing chemical changes in other organic products, especially the neutral ternary bodies, causing one kind to be transformed into another, or even the decomposition of a part into alcohol, acetic acid, and finally into carbonic acid and water (as in germination, &c), — itself remaining the while essentially unaltered. 356. The constant attraction of the protoplasm from the com- pleted into the forming parts of the plants explains how it is, that so small a percentage of azotized matter should be capable of playing such an all-important part in the vegetable economy. It does its work with little loss of material, and no portion of it is fixed in the tissues. At least, the little that remains in old parts is capa- ble of being washed out, showing that it forms no integral part of the fabric. This explains why the heartwood of trees yields barely a trace of nitrogen, while the sap-wood yields an appreciable amount, and the cambium-layer and all parts of recent formation, such as the buds, young shoots, and rootlets, always contain a notable proportion of it. This gives the reason, also, why sap-wood is so liable to decay (induced by the proteine), the more so in proportion to its newness and the quantity of sap it contains, while the completed heart-wood is so durable. The azotized matter rapidly diminishes in the stem and herbage during flowering, while it accumulates in the forming fruit, and is finally condensed in the seeds (which have a larger per- centage than any other organ), ready to subserve the same office in the development of the embryo plant it contains.* 357. When wheat-flour, kneaded into dough, is subjected to the prolonged action of water, the starch is washed away, and a tena- cious, elastic residue, the Gluten of the flour, which gives it the capability of being raised, remains. This contains nearly all the proteine compounds of the seed, mixed with some fatty matters (which may be removed by alcohol and ether) and with a little cellulose. The azotized products constitute from eight to thirty per cent of the weight of wheat-flour : the proportion varies greatly * The cotyledons of peas and beans, according to Mr. Rigg, contain from 100 to 140 parts, and the plumule about 200 parts, of nitrogen, to 1,000 parts of carbon. 17* 198 THE FOOD AND NUTRITION OF PLANTS. under different circumstances, but it is always largest when the soil is well supplied with manures that abound in nitrogen. The gluten of wheat is a mixture of four isomeric quaternary products, distin- guished by chemists under the names Fibrine (identical in nature with that which forms the muscles of animals), Albumen (of the same nature as animal albumen), Caseine (identical with the curd of milk), and Glutine. In beans and all kinds of pulse, or seeds of Legu- minous plants, the azotized matter principally occurs in the form of Legumine, which is nearly intermediate in character between albu- men and caseine. 358. Comparing now these principal products of assimilation in plants with the inorganic materials from which they must needs be formed, it may clearly be perceived that the principal result of vege- tation, as concerns the atmosphere, from which plants draw their food, consists in the withdrawal of water, of a little ammonia, and of a large proportion of carbonic acid, and of the restoration of oxygen. The latter is a constant effect of vegetation and the measure of its amount. As respects the fabric of the plant, the sole consequences of its formation upon the air are the withdrawal of a small quantity of water, and of a large amount of carbonic acid gas, and the resto- ration of the oxygen of the latter. In the formation of its azotized materials, a portion of ammonia or of some equn-alent compound of nitrogen is also withdrawn. It is time, indeed, that leaves decom- pose carbonic acid only in daylight ; and that they sometimes give a quantity of carbonic acid to the air in the night, especially when vegetation languishes, or even take from it a little oxygen. But this does not affect the general result, nor require any qualification of the general statement. The work simply ceases when light is withdrawn. The plant is then merely in a passive state. Yet, whenever exhalation from the leaves slowly continues in darkness, the carbonic acid Avhich the water holds necessarily flies off with it, during the interruption to vegetation, into the atmosphere from which the plant took it. So much of the crude sap, or raw mate- rial, merely runs to waste. Furthermore, it must be remembered that the decomposition of carbonic acid in vegetation is in direct op- position to ordinary chemical affinity ; or, in other words, that all organized matter is in a state corresponding to that of unstable equilibrium. Consequently, when light is withdrawn, ordinary chemical forces may perhaps to some extent resume their sway, the oxygen of the air combine with some of the newly deposited carbon INFLUENCE OF VEGETATION ON THE ATMOSPHERE. 199 to reproduce a little carbonic acid, and thus demolish a portion of the rising vegetable structure which the setting sun left, as it were, in an unfinished or unstable state. This is what actually takes place in a dead plant at all times, and whenever an herb is kept in pro- longed darkness ; chemical forces, exerting their power uncontrolled, demolish the whole vegetable fabric, beginning with the chlorophyll (as we observe in blanching Celery), and at length resolve it into the carbonic acid and water from which it was formed. But this must all be placed to the account of decomposing, not of groioing vegetation ; and even if it were a universal phenomenon, which is by no means the case,* would not affect the general statement, that, by so much as plants groiv, they decompose carbonic acid and give its oxygen to the air ; or, in other words, purify the air. 359. Every six pounds of carbon in existing plants have withdrawn twenty-two pounds of carbonic acid gas from the atmosphere, and replaced it with sixteen pounds of oxygen gas, occupying the same bulk. To form some general conception of the extent of the influ- ence of vegetation upon the air we breathe, therefore, we should compute the quantity of carbon, or charcoal, that is contained in the * It is stated that many ordinary plants, when in full health and vigorous vegetation, impart no carbonic acid to the air during the night. — See Pepys, in Philosophical Transactions, for 1 843. — Plants deteriorate the air only in their decay, and in peculiar processes, distinct from vegetation and directly the re- verse of assimilation ; as in germination, for instance, where the proteine in- duces the decomposition of a portion of the store of assimilated matter, in order that the rest may he brought into a serviceable condition. The evolution of carbonic acid by plants, therefore, when it occurs, is no part of vegetation. And it is by a false analogy that this loss which plants sustain in the night has been dignified with the name of vegetable respiration, and vegetables said to vitiate the atmosphere, just like animals, by their respiration, while they purify it by their digestion. If, indeed, this were a constant function, in any way contributing to maintain the life and health of the plant, it might be properly enough compared with the respiration of animals, which is itself a decomposing operation. But thus is not the case. And herein is a characteristic difference between vegetables and animals : the tissues of the latter require constant interstitial renewal by nutrition, new particles replacing the old, which are removed and restored to the mineral world by respiration : while in plants there is no such renewal, but the fabric, once completed, remains unchanged, ceases to be nourished, and conse- quently soon loses its vitality ; while new parts are continually formed farther on to take their places, to be in turn abandoned. Plants, therefore, having no decomposition and recomposition of any completed fabric, cannot properly be said to have the function of respiration. 200 THE FOOD AND NUTRITION OF PLANTS. forests and herbage of the world, and add to the estimate all that exists in the soil, as vegetable mould, peat, and in other forms ; all that is locked up in the vast deposits of coal (the product of the vegetation of bygone ages) ; and, finally, all that pertains to the whole existent animal kingdom ; — and we shall have the aggregate amount of a single, though the largest, element which vegetation has withdrawn from the atmosphere. By multiplying this vast amount of carbon by sixteen, and dividing it by six, we obtain an expression of the number of pounds of oxygen gas that have in this process been supplied to the atmosphere. 3 GO. Rightly to understand the object and consequences of this immense operation, which has been going on ever since vegetation began, it should be noted, that, so far as Ave know, vegetation is the only operation in nature which gives to the air free oxygen gas, that indispensable requisite to animal life. There is no other pro- vision for maintaining the supply. The prevailing chemical ten- dencies, on the contrary, take oxygen from the air. Few of the materials of the earth's crust are saturated with it ; some of them still absorb a portion from the air in the changes they undergo ; and none of them give it back in the free state in which they took it, — in a state to support animal life, — by any known natural process, at least upon any considerable scale. Animals all con- sume oxygen at every moment of their life, giving to the air carbonic acid in its room ; and when dead, their bodies consume a further por- tion in decomposition. Decomposing vegetable matter produces the same result. Its carbon, taking oxygen from the air, is likewise restored in the form of carbonic acid. Combustion, as in burning our fuel, amounts to precisely the same thing ; it is merely rapid decay. The carbon which the trees of the forest have been for centuries gathering from the air, their prostrate decaying trunks may almost as slowly restore to the air, in the original form of carbonic acid. But if set on fire, the same result may be accom- plished in a day. All these causes conspire to rob the air of its life-sustaining oxygen. The original supply is indeed so vast, that, were there no natural compensation, centuries upon centuries would elapse before the amount of oxygen could be so much reduced, or that of carbonic acid increased, as to affect the existence of the present races of animals. But such a period would eventually arrive, were there no natural provision for the decomposition of the carbonic acid constantly poured into the air from these various RELATIONS OF THE VEGETABLE AND ANIMAL KINGDOMS. 201 sources, and for the restoration of its oxygen. The needful com- pensation is found in the vegetable kingdom. While animals con- sume the oxygen of the air, and give back carbonic acid which is injurious to their life, this carbonic acid is the principal element of the food of vegetables, is consumed and decomposed by them, and its oxygen restored for the use of animals. Hence the perfect adap- tation of the two great kingdoms of living beings to each other ; — each removing from the atmosphere what would be noxious to the other; — each yielding to the atmosphere what is essential to the continued existence of the other.* 3G1. The relations of simple vegetation, under this aspect, to the mineral kingdom on the one hand, and the animal kingdom on the other, are simply set forth in the first part of the diagram placed at the close of this chapter. 3G2. But, besides this remotely essential office in purifying the air, the vegetable kingdom renders to the animal another service so immediate, that its failure for a single year would nearly depop- ulate the earth ; namely, in providing the necessary food for the whole animal kingdom. It is under this view that the great office of vegetation in the general economy of the world is to be contem- plated. Plants are the sole producers of nourishment. They alone transform mineral, chiefly atmospheric materials, they condense air, into organized matter. While they thus produce upon a vast scale, they consume or destroy comparatively little; and this never in proper vegetation, but in some special processes hereafter to be con- sidered (370). Often when they appear to consume their own pro- ducts, they only transform and transfer them, as when the starch of the potato is converted into new shoots and foliage. 363. Animals consume what vegetables produce. They them- selves produce nothing directly from the mineral world. The herbivorous animals take from vegetables the organized matter which they have produced ; — a part of it they consume, and in respiration restore the materials to the atmosphere, from which * It is plain, however, that, while the animal kingdom is entirely dependent on the vegetable, the latter is independent of the former, and might have existed alone. The decaying races of plants, giving back their carbon to the air and to the soil by decay, would furnish food for their successors. And since all the carbonic acid which animals render to the air in respiration they have derived from their vegetable food, this would in time have found its way back to the air, for the use of new generations of plants, without the intervention of animals. At most, they merely expedite its return. 202 THE FOOD AND NUTRITION OF PLANTS. plants derived them, in the veiy form in which they were taken, namely, as carbonic acid and water. The portion they accumulate in their tissues constitutes the food of carnivorous animals ; who consume and return to the air the greater part during life, and the remainder in decay after death. The atmosphere, therefore, out of which plants create nourishment, and to which animals as they con- sume return it, forms the necessary link between the animal and vegetable kingdoms, and completes the great cycle of organic exist- ence. Organized matter passes through various stages in vege- tables, through others in the herbivorous animals, and undergoes its final transformations in the carnivorous animals. Portions are con- sumed at every stage, and restored to the mineral kingdom, to which the whole, having accomplished its revolution, finally returns. 364. Moreover, plants not only furnish all the materials of the animal fabric, but furnish each principal constituent ready formed, so that the animal has only to appropriate it. The food of animals is of two kinds; — 1. that which serves to support respiration and maintain the animal heat ; 2. that which is capable of forming a portion of the animal fabric, of its flesh and bones. The ternary vegetable products furnish the first, in the form of sugar, vegetable jelly, stai*ch, oil, &c, and even cellulose ; substances which, contain- ing no nitrogen, cannot form an integral part of the animal frame, but, conveyed into the blood, are decomposed in respiration ; the carbon and the excess of hydrogen combining with the oxygen of the air, to which they are restored in the form of carbonic acid and water. Any portion not required by the immediate demands of res- piration is stored in the tissues in the form of fat, (which the animal may either accumulate directly from the oily and waxy matters in iis vegetable food, or produce by an alteration of the starch and sugar,) as a provision for future use : a deficiency of such materials subjects the tissues themselves, or the proper supporting food, to im- mediate decomposition in respiration. The quaternary or azotized products furnish the proper materials of the animal frame, the fibrine, caseine, albumen, &c. being directly appropriated from the vegetable food to form the blood, muscles, &c. ; while a slight trans- formation of them gives origin to gelatine, of which the sinews, carti- lages, and the organic part of the bones, consist. The earthy por- tion of the bones, the iron in the blood, and the saline ingredients of the animal body, are drawn from the earthy constituents (336) of the plants upon which the animal feeds. The animal merely ap- RELATIONS OF THE THREE KINGDOMS OF NATURE. 203 propriates and accumulates these already organizable materials, changing them, it may be, little by little, as he destroys them, but rendering them all back (those of the first class through the lungs, of the second through the kidneys) finally to the earth and air, from which, and in the condition in which, the vegetable took them. 865. The general relations of vegetation to the mineral and ani- mal kingdoms are exhibited in the subjoined diagram. H C2 •— I J5 OS o o - a . 'A H op ? < «!H < £ << % * fc O ° 3 § a fc Z 5 ° o w o H O M H ■< i-) W « H S ■ .-s ■a © 5-a 'Hoc! oo B to c § a S gj» o 5*5 s o a £ w o ^£ 2 3 Ec-a I >><„ 3 E 3 '3 ' = o 5 5 « | o a s t a o' o a 65 2 B 3 2 M :o 6 £ * OP 204 FLOWERING AND ITS CONSEQUENCES. CHAPTER VII. OP FLOWERING AND ITS CONSEQUENCES. 366. Plants have thus far heen considered only as respects their Organs of Vegetation, — those which essentially constitute the vegetable being, by which it grows, deriving its support from the surrounding air and soil, and converting these inorganic mate- rials into its own organized substance. As every additional supply of nourishment furnishes materials for the development of new branches, roots, and leaves, thus multiplying both those organs which receive food and those which assimilate it, it would seem that, apart from accidents, the increase and extension of plants would be limited only by the failure of an adequate supply of nourishment. After a certain period, however, varying in different species, but nearly con- stant in each, a change ensues, which controls this otherwise indefi- nite extent of the branches. A portion of the buds, instead of elon- gating into branches, are developed in the form of Flowers ; and nourishment which would otherwise contribute to the general in- crease of the plant, is devoted to their production, and to the matu- ration of the fruit and seeds. 367. Flowering an Exhaustive Process. Plants begin to bear flowers at a nearly determinate period for each species ; which is dependent partly upon constitutional causes, and partly upon the requisite sup- ply of nutritive matter in their system. For, since the flower and fruit draw largely upon the powers and nourishment of the plant, while they yield nothing in return, fructification is an exhaustive process, and a due accumulation of food is requisite to sustain it.* * "When the branch of a fruit-tree, which is sterile or does not perfect its blos- soms, is ringed or girdled (by the removal of a narrow ring of bark), the elab- orated juices, being arrested in their downward course, are accumulated in the branch, which is thus enabled to produce fruit abundantly ; while the shoots that appear below the ring, being fed by the much weaker ascending sap, do not blossom, but push forth into leafy branches. So the flowers of most trees and shrubs that bear large or fleshy fruit are produced from lateral buds, resting directly upon the wood of the previous year, in which a quantity of nutritive matter is deposited. So, also, a seedling shoot, which would not flower for several years if left to itself, blossoms the next season when inserted as a graft into an older trunk, from whose accumulated stock it draws. FLOWERING AN EXHAUSTIVE TROCESS. 205 Annuals flower in a few weeks or months after they spring from the seed, when they have little nourishment stored up in their tissue ; and their lives are destroyed by the process (144) : biennials flower after a longer period, rapidly exhausting the nourishment accumu- lated in the root during the previous season, and then perishing (145) ; while shrubs and trees do not commence flowering until they are sufficiently established to endure it. The exhaustion con- sequent upon flowering, however, is often exhibited in fruit-trees, which, after producing an excessive crop (especially of late fruits, such as apples), sometimes fail to bear the succeeding year. When the crop of one year fails, the nourishment which it would have ap- propriated accumulates, and the tree may bear more abundantly the following season, and so on alternately from year to year. 368. The actual consumption of nourishment in flowering may be shown in a variety of ways ; as by the rapid disappearance of the farinaceous or saccharine store in the roots of the Carrot, Beet, &c. when they begin to flower, leaving them light, dry, and empty ; and by the rapid diminution of the sugar in the stalks of the Sugar- cane and of Maize at the same period. The stalks are therefore cut for making sugar just before the flowers expand, when they contain the greatest amount of saccharine matter. 369. The consequences of this exhaustion upon the duration of plants are further illustrated by the facility with which annuals may be changed into biennials, or their life prolonged indefinitely by preventing their flowering ; while they perish whenever they bear flowers and seed, whether during the first or any succeeding year. Thus, a common annual Larkspur has given rise to a double-flowered variety in the gardens, which bears no seed, and has therefore be- come a perennial. Cabbage-stumps, which are planted for seed, may be made to bear heads the second year by destroying the flower- shoots as they arise ; and the process may be continued from year to year, thus converting a biennial into a kind of perennial plant. The effect of flowering upon the longevity of the individual is strikingly shown by the Agave, or Century-plant, — so called because it flow- ers in our conservatories only after the lapse of a hundred, or at least a great number of years ; although, in its native sultry climate, it generally flowers when five or six years old. But whenever this occurs, the sweet juice with which it is filled at the time (which by fermentation forms pulque, the inebriating drink of the Mexicans) is consumed at a rate answering to the astonishing rapidity with which 18 206 FLOWERING AND ITS CONSEQUENCES. its huge flower-stalk shoots forth (24), and the whole plant inevita- bly perishes when the seeds have ripened. So, also, the Corypha, or Talipot-tree, a magnificent Oriental Palm, which lives to a great age and attains an imposing altitude (bearing a crown of leaves, each blade of which is often thirty feet in circumference), flowers only once ; but it then bears an enormous number of blossoms, suc- ceeded by a crop of nuts sufficient to supply a large district with seed ; and the tree perishes from the exhaustion. 370. Flowering and fruiting, then, draw largely upon the plant's resources, Avhile they give back nothing in return. In these opera- tions, as also in germination, vegetables act as true consumers (like animals, 363), decomposing their own products, and giving back carbonic acid and water to the air, instead of taking these materials from the air. It is in flowering that they actually consume most. In fruiting, although a large quantity of nourishment is taken from the plants, this is mostly accumulated in the fruit and seed, in a con- centrated form, for the future use of the new individual in the seed. 371. The real consumption of nourishment by the flower is shown by the action of flowers upon the air, so different from that of leaves. "While the foliage withdraws carbonic acid from the air, and re- stores oxygen (346, 358), flowers take a small portion of oxygen from the air, and give back carbonic acid. "While leaves, therefore, purify the air we breathe, flowers contaminate it ; though, of course, only to a degree which is relatively and absolutely insignificant. This process is necessarily attended by the 372. Evolution Of Heat. When carbon is consumed as fuel, and by the oxygen of the air converted into carbonic acid, an amount of heat is evolved directly proportionate to the quantity of carbon consumed, or of carbonic acid produced. Precisely the same amount is more slowly generated during the gradual decomposition of the same quantity of vegetable matter by decay, — a heat which is employed by the gardener when he makes hot-beds of tan, decay- ing leaves, and manure, — or by the breathing of animals, which maintains their elevated temperature (364). The conversion of a given amount of carbon and hydrogen into carbonic acid and water, under whatever circumstances it may take place, and whether slowly or rapidly, generates in all cases the very same amount of heat. Now, since flowers consume carbon and produce carbonic acid, acting in this respect like animals, they ought to evolve heat in proportion to that consumption. This, in fact, they do. The evolution of heat EVOLUTION OF HEAT. 207 in blossoming was first observed by Lamarck, about seventy years ago, in tbe European Arum, which, just as the flowers open, " grows hot, as if it were about to burn." It was afterwards shown by Saus- sure in a number of flowers, such as those of the Bignonia, Gourd, and Tuberose, and the heat was shown to be in direct proportion to the consumption of the oxygen of the air, or, in other words, of the carbon of the plant. The increase of temperature, in these cases, was measured by common instruments. But now that themio-elec- tric apparatus affords the means of measuring variations inappre- ciable by the most delicate thermometer, the heat generated by an ordinary cluster of blossoms may be detected. The phenomenon is most striking in the case of some large tropical plants of the Arum family, where an immense number of blossoms are crowded together and muffled by a hooded leaf, or spathe (390), which confines and rever- berates the heat. In some of these, the temperature rises at times to twenty or even fifty degrees (Fahrenheit) above that of the sur- rounding air. This increase of temperature occurs daily, from the time the flowers open until they fade, but is most striking during the shedding of the pollen. At night, the temperature falls nearly to that of the surrounding air ; but in the course of the morning the heat comes on, as it were like a paroxysm of fever, attaining the maximum, day after day, very nearly at the same hour of the after- noon, and gradually declining toAvards evening. In ordinary cases, the heat of flowering is more than counterbalanced by the vaporiza- tion of the sap and the absorption of solar heat by the foliage ; so that the actual temperature of a leafy plant in summer is lower than that of the atmosphere. 373. We have remarked that the principal consumption takes place in the flower ; and that a store is laid up in the fruit and seed. But much even of this store is consumed when the seed germinates ; and in germination, as is seen in the malting of barley, a large amount of organic matter is decomposed into carbonic acid and water, and a proportionate quantity of heat is evolved. By a not veiy violent metaphor it may be said, therefore, that the fabled Phoe- nix is realized in the Century-plant (369), which, after living a hun- dred years, consumes itself in producing and giving life to its off- spring, who literally rise from its ashes. 374. Plants need a Season Of Rest. When plants are in luxuriant growth, rapidly pushing forth leafy branches, they are not apt to produce flower-buds. Our fruit-trees, in very moist seasons, or 208 FLOWERING AND ITS CONSEQUENCES. •when cultivated in too rich a soil, often grow luxuriantly, but do not blossom. The same thing is observed when our Northern fruit-trees are transported into tropical climates. On the other hand, -whatever checks this continuous growth, without affecting the health of the individual, causes blossoms to appear earlier and more abundantly than they otherwise would. It is for this reason that transplanted fruit-trees incline to blossom the first season after their removal, though they may not do so again for several years. A state of com- parative rest seems needful to the transformation by which flowers are formed. It is in autumn, or at least after the vigorous vegeta- tion of the season is over, that our trees and shrubs, and most peren- nial herbs, form the flower-buds of the ensuing year. 375. The requisite annual season of repose, which in temperate climates is attained by the lowering of the temperature in autumn and winter, is scarcely less marked in many tropical countries, where winter is unknown. But the result is there brought about, not by cold, but by heat and dryness. The Cape of Good Hope, the Canary Islands, and the southern and interior parts of California, may be taken as illustrations. In the Canaries, the growing season is from November to March, — the winter of the northern hemi- sphere ; — their winter also, as it is the coolest season, the mean temperature being 06° Fahr. But the rains fall regularly, and vegetation is active ; while in summer, from April to October, it very seldom rains, and the mean temperature is as high as 73°. During this dry season, when the scorching sun reduces the soil nearly to the dryness and consistence of brick, ordinary vegetation almost completely disappears ; and the Fig-Marigolds, Euphorbias, and other succulent plants, which, fitted to this condition of things, alone remain green, not unaptly represent the Firs and other ever- greens of high northern latitudes. The dry heat there brings about the same state of vegetable repose as cold with us. The roots and bulbs then lie dormant beneath the sunburnt crust, just as they do in our frozen soil. "When the rainy season sets in, and the crust is softened by moisture, they are excited into growth under a dimin- ished temperature, just as with us by heat ; and the ready-formed flower-buds are suddenly developed, clothing at once the arid waste with a profusion of blossoms (194). The vegetation of such regions consists mainly of succulents, which are able to live through the drought and exposure ; of bulbous plants, which run through their course before the drought becomes severe, then lose their THE INFLORESCENCE. 209 foliage, while the bud remains quiescent, safely protected under ground until the rainy season returns ; and of annuals, which make their whole growth in a few weeks, and ripen their seeds, in which state the species securely passes the arid season. 376. These considerations elucidate the process of forcing plants, and other operations of horticulture, by which we are enabled to obtain in winter the flowers and fruits of summer. The gardener accomplishes these results principally by skilful alterations of the natural period of repose. He gives the plant an artificial period of rest by dryness at the season when he cannot command cold, and then, by the influence of heat, light, and moisture, which he can always command, causes it to grow at a season when it would have been quiescent. Thus he retards or advances, at will, the periods of flowering and of rest, or in time completely inverts them. CHAPTER VIII. OP THE INFLORESCENCE. 377. Inflorescence is the term used to designate the arrangement of flowers upon the stem or branch. The flower, like the branch, is evolved from a bud. Flower-buds and leaf-buds are often so similar in appearance, that it is difficult to distinguish one from the other before their expansion. The most conspicuous parts of the flower are so obviously analogous to the leaves of a branch, that they are called in common language the leaves of the flower. Such a flower as the double Camellia appears as if composed of a rosette of white or colored leaves, resembling, except in their color and texture, the clusters of leaves which are crowded on the offsets of such plants as the Houseleek (Fig. 207). We therefore naturally regard a flower-bud as analogous to a leaf-bud ; and a flower, con- sequently, as analogous to a short leafy branch. 378. This analogy is confirmed by the position which flowers oc- cupy. They appear at the same situations as ordinary buds, and at no other ; that is, they occupy the extremity of the stem or branch, and the axil of the leaves (159, 1G5). Consequently, the arrange- 18* 210 THE INFLORESCENCE. ment of the leaves governs the whole arrangement of the blossoms, as well as that of the branches. The almost endless variety of modes in which flowers are clustered upon the stem, many of them exhibiting the most graceful of natural forms, all implicitly follow the general law which has controlled the whole development of the vege- table from the beginning. "We have, throughout, merely buds termi- nating the stem and branches, and buds from the axil of the leaves. 379. The simplest kind of inflorescence is, of course, that of a solitary flower, — a sin- gle flower-stalk bearing a single flower ; as in Fig. 306 and Fig. 327. The flower is solitary in both these instances ; but 3° 6 in the latter case it oc- cupies the summit of the stem, that is, it stands in the place of a terminal bud ; in the former it arises from the axil of a leaf, or represents an axillary bud. These two cases exhibit, in their great- est simplicity, the two plans of inflorescence, to one or the other of which all flower-clusters belong. 380. We begin with the second of these plans ; in which the flowers all spring from axillary buds ; while the terminal bud, de- veloping as an ordinary branch, continues the stem or axis indefi- nitely. For the stem in such case may continue to elongate, and produce a flower in the axil of every leaf, until its powers are ex- hausted (Fig. 307). This gives rise, therefore, to what is called 381. Indefinite or Indeterminate Inflorescence. The primary axis is here never terminated by a flower ; but the secondary axes (from axillary buds) are thus terminated. The various forms of indefi- nite inflorescence which in descriptive botany are distinguished by special names, as might be expected, run into one another through intermediate gradations. In nature they are not so absolutely fixed as in our written definitions ; and whether this or that name should be used in a particular case is often a matter of fancy. The sub- joined account of the principal kinds will at the same time bring to view the connection between them. 382. The principal kinds of indefinite inflorescence which have received distinctive names are the Raceme, the Corymb, the Umbel, the Spike, the Head, the Spadix, the Catkin, and the Panicle. [FIG. 306. A flowering branch of Moneywort, Lyshnachia nummularia. INDETERMINATE INFLORESCENCE. 211 383. Before illustrating these, one or two terms, of common oc- currence, may be denned. A flower which has no stalk to support it, but which sits directly on the stem or axis it proceeds from, is said to be sessile. If raised on a stalk, this is called its Peduncle. If the whole flower-cluster is raised on a stalk, this keeps the name of peduncle, or common peduncle (Fig. 307, jo) ; and the stalk of each particular flower, if it have any, takes the name of Pedicel or partial peduncle (p 1 ). The portion of the general stalk along which flowers are disposed is called the axis of in- florescence, or, when covered with sessile flowers, the rhachis (backbone), and sometimes (as when thick and covered with crowded flowers) the receptacle. The leaves of a flower-cluster generally are termed Bracts. But when we wish particularly to distin- guish their sorts, those on the peduncle, or main axis, and which have a flower in their axil, take the name of Bracts (Fig. 307, b) ; and those on the pedicels or partial flower-stalks, if any, that of Bractlets or Bracteoles (&'). The bracts are often reduced to a minute size, so as to escape ordinary notice : they very frequently fall off when the flower-bud in their axil expands, or even earlier ; and sometimes, as in the greater part of the Mustard family, they altogether fail to appear. 384. A Raceme (Fig. 307, 308, 315) is that form of flower-cluster in which the flowers, each on their own footstalk or pedicel, are arranged along a common stalk or axis of infloresence ; as in the Lily of the Valley, Currant, Choke-Cherry, Barberry, &c. The lowest blossoms of a raceme are of course the oldest, and therefore open first, and the order of blossoming is ascending, from the bot- tom to the top. The summit, never being stopped by a terminal flower, may go on to grow, and often does so (as in the Snowberry, Shepherd's Purse, &c), producing lateral flowers one after another throughout the season. In the raceme, the axis of inflorescence is more or less elongated, and the pedicels are about equal in length. 385. A Corymb (Fig. 309, 319) is the same as a raceme, except that the lower pedicels are elongated, so as to form a level-topped or slightly convex bunch of flowers ; as in the Hawthorn, &c. FIG. 307. A Raceme, -with a general peduncle (p), pedicels (p'), bracts (b), and bractlets (V). ¥ 212 THE INFLORESCENCE. 386. All Umbel (Fig. 310) differs from a corymb only in having all the pedicels arising from the same apparent point, so as to resem- ble the rays of an umbrella; — the general peduncle, in this case, bearing several flowers without any perceptible elongation of the axis of infloresence. The Primrose and the Milkweed afford familiar examples of the simple umbel. 387. A corymb being evidently the same as a raceme with a short main axis, and an umbel the same as a corymb with a still shorter axis, it is evident that the outer flowers of an umbel or corymb correspond to the lowermost in the raceme, and that these will first expand, the blossoming pro- ceeding regularly from the base to the apex, or (which is the same thing) from the circumference to the centre. This mode of development uniformly takes place when the flowers arise from axil- lary buds ; on which account the indefi- nite mode of inflorescence is also called the centripetal. 388. In all the foregoing cases, the flowers are raised on stalks, or pedicels. When these are wanting, or so short as not to be apparent, a Spike or Head is produced. 389. A Spike is the same as the raceme, except that the flowers are sessile ; as in the Plantain (Fig. 311) and Mullein. It is an in- FIG. 308. A raceme. 309. A corymb. 310. An umbel. FIG. 311. Young spike of Plantago major. 312. Catkin of White Birch. INDETERMINATE INFLORESCENCE. 213 determinate infloresence, with the primary axis elongated, and the flowers destitute of pedicels or with only very short ones. Two varieties of the spike have received independent names, viz. the Spadix and the Ament. 390. A Spadix is a fleshy spike enveloped by a large bract or mod- ified leaf, called a Spathe, as in Calla palustris (Fig. 313), the Indian Turnip (Fig. 314), and the Skunk Cabbage (Fig. 1205). 391. An Ament, or Catkin, is merely that kind of spike with scaly bracts borne by the Birch (Fig. 312), Poplar, Willow, and, as to one of the two sorts of flowers, by the Oak, Walnut, and Hickory, which are accordingly called amentaceous trees. Catkins usually fall off in one piece, after flowering or fruiting, especially sterile catkins. 392. The Head, or Capitulum, is a globular cluster of sessile flowers, like that of Clover, the Button-Bush (Fig. 320), and the balls of the Buttonwood or Plane-tree. It is a many-flowered centripetal in- florescence, in which neither the primary axis nor the secondary axes are at all lengthened. We may view it either as an umbel without any pedicels, or as a spike with a very short axis. Gen- erally it is of the latter character, as is evident in a Clover-head, where what was first a head frequently elongates into a spike as it grows older. FIG. 313, 314. Spadix of Calla and of Arum, with the spathe. 315. A raceme of Cherry. 317. A cyme. 318. Panicle of Meadow-Grass. 319. A corymb. 214 THE INFLORESCENCE. 393. The base both of the head and the umbel is frequently fur- nished with a number of imperfect leaves or bracts, crowded into a cluster or whorl, termed an Involucre. The involucre assumes a great variety of forms ; sometimes resembling a calyx ; and some- FIG. 320. Head of flowers of the Button-bush, Cephalanthus occidentals. FIG. 321. Plant of Cornus Canadensis, with its four-leaved involucre around a cluster of small flowers. 322. A separate flower enlarged. FIG. 323. Flowering branch of Cichory, with two heads of ligulate flowers. INDETERMINATE INFLORESCENCE. 215 times (as in Cornus Florida, or the common Dogwood, and C. Cana- densis, Fig. 321) becoming petal-like, and much more showy than the blossom itself. Here it is at once distinguished from the calyx or corolla by its including a number of flowers. Sometimes, how- ever, as in the Mallow and Hibiscus, the involucre forms a kind of outer calyx to each flower. 394. The axis, or rhachis (382), of a head is called its Recep- tacle. Frequently, instead of being globular or oblong, it is flat or depressed, and dilated horizontally, so as to allow a large number of flowers to stand on its level or merely convex surface ; as in the Sun- flower, Aster, Marigold, Dandelion, and Cichory (Fig. 323). Here, as in Fig. 321, a set of bracts form an involucre, surrounding the dense head of flowers. And as the involucre considerably resembles a calyx, Avhile the outer flowers, often of a peculiar sort, are readily mistaken for petals, the head in these and similar plants was called a compound jftower by the older botanists. Fig. 324 rep- resents a section through a head of such flowers in a Co- reopsis ; and Fig. 325 is a slice of the same, more enlarged, displaying some of the sepa- rate flowers. In Coreopsis, as in the Sunflower, Yarrow, 324 &c., each blossom of the head is subtended by its bract (b) ; and the bracts in such cases are called Palece or Chaff. 395. The Fig presents a case of very singular inflorescence FIG. 324. Vertical section of a head of flowers of a Coreopsis. FIG. 325. A slice of Fig. 324, more enlarged, with one tubular perfect flower (a) left stand- ing on the receptacle, and subtended by its bract or chaff (b); also one ligulate and neutral ray- flower (c), and part of another: d, section of bracts or leaves of the involucre. 216 THE INFLORESCENCE. (Fig. 590-592), where the flowers apparently occupy the inside instead of the outside of the axis, being enclosed within the fleshy receptacle, which is hollow and nearly closed at the top. So that while a Sunflower, or the like, is an inflorescence imitating a blos- som, a fig is an inflorescence imitating a fruit. Indeed, it is much like a mulberry (Fig. 593) or a pine-apple, turned inside out. 396. The foregoing are all forms of simple inflorescence ; the ramification not passing beyond the first step ; the lateral buds being at once terminated by a single flower. But the lateral flower- stalks may themselves branch, just as ordinary branches give rise to branchlets : then the inflorescence becomes compound. If the branches of a raceme are prolonged, and bear other flowers on pedi- cels similarly arranged, a compound raceme is produced ; or if the flowers are sessile, a compound sjrike is formed. A corymb, the branches of which are similarly divided, forms a compound corymb ; and an umbel, where the branches (often called rays) bear smaller umbels at their apex, is termed a compound um- bel ; as in the Caraway, Parsnip, and almost all the species of the family UmbeUiferse, which is so named on this account. 397. For these secondary umbels, a good Eng- lish name has been employed by Dr. Darlington, that of Umbellets. Their involucre, when they have any, is distinguished from that of the principal umbel by the name of Invoeucel. 398. When the inflorescence is compound, it is readily seen that the different kinds of inflores- cence may be combined ; the first ramification following one plan, and the subdivision another. The combination is usually expressed by a de- scriptive phrase, as " spikes racemose, or ra- cemed," " heads corymbose," &c. The combina- tion of the raceme and the corymb or the cyme gives rise to a form of inflorescence which has a technical name, viz. : — 399. The Panicle. This is formed when the secondary axes of a raceme branch in a corymbose manner, as in most Grasses (Fig. 318, 32 G), or when those of a corymb divide in the manner of a raceme. And the name is applied to almost any open FIG. 326. A panicle. (Compare with Fig. 307.) DETERMINATE INFLORESCENCE. 217 and more or less elongated inflorescence which is irregularly branched twice, thrice, or a greater number of times. 400. A Th)TSUS, or Thyi'SC, is a compact panicle of a pyramidal, oval, or oblong outline ; such as the cluster of flowers of the Lilac and Horsechestnut, a bunch of grapes, &c. 401. Definite or Determinate Inflorescence. In this class, the flowers all represent terminal buds (380). The primary axis is directly terminated by a single flower-bud, as in Fig. 327, and its growth is of course arrested. Here we have a solitary terminal flower. Further growth can take place only by the development of secondary axes from axillary buds. These may develop at once as peduncles, or as leafy branches ; but they are in either case arrested, sooner or later, by a flower-bud, just as the primary axis was (Fig. 328). If further development ensues, it is by the production of branches of the third order, from the axils of leaves or bracts on the branches of the second order (Fig. 329) ; and so on. Hence this mode of inflo- rescence is said to be definite or determinate, in contradistinction to the indeterminate mode, already treated of, where the primary or leading axes elongate indefinitely, or merely cease to grow from the failure of nourishment, or some other extrinsic cause. The most common and most regular cases of determinate inflorescence occur in opposite-leaved plants, for obvious reasons ; and such are accordingly chosen for the subjoined illustrations. But the Rose, Potentilla, and Buttercup furnish familiar examples of the kind in alternate-leaved plants. 402. The determinate mode of inflorescence assumes forms which may closely imitate those of the indeterminate kind, already de- scribed, and Avith which they have been confounded. When, for ex- ample, all the secondary axes connected with the inflorescence are arrested by terminal flowers, without any onward growth except FIG. 327 - 329. Diagrams of regular forms of determinate or centrifugal inflorefffnce. 19 218 THE INFLORESCENCE. what forms their footstalks or pedicels, and these are nearly equal in length, a raeerae-like inflorescence is produced, as in Fig. 330 ; or when the flowers have scarcely any pedicels, the spike is imitated. These are distinguished from the true raceme and spike, however, by the reverse order of development of the blossoms ; the terminal one opening earliest, and the others expanding in succession from above down- wards ; while the blossoming of the raceme proceeds from below upwards. Or when, by the elongation of the lower secondary axes, a corymb is imitated, the flowers are found to expand in succession from the centre of each ramification, beginning in the centre of the cluster, while the contrary occurs in the corymb. That is, Avhile the order in indeterminate inflorescence is centripetal (387), that of the determinate mode is centrifugal. When the determinate inflorescence as- sumes the flattish or convex form, which it more com- monly does, it has a distinctive name, viz. : — 403. The Cyme. This is a flat-topped, rounded or expanded in- florescence, whether simple or compound, of the determinate class ; of which those of the Laurustinus, Elder, Dogwood, and Hydrangea (Fig. 420) are fully developed and characteristic examples. In com- pound and compact cymes, such as those of the Laurustinus, Dogwood, &c, the leaves or bracts are usually minute, rudimentary, or abor- tive, and all the numerous flower-buds of the cluster are fully formed before any of them expand ; and the blossoming then runs through the whole cluster in a short time, commencing in the centre of the cyme, and then in the centre of each of its branches, and thence pro- ceeding centrifugally. But in the Chickweeds (Fig. 331), in Hy- pericum, and many similar plants, the successive production of the branches and the evolution of the flowers, beginning with that Avhich arrests the growth of the primary axis, go on gradually through the Avhole summer, until the powers of the plant are exhausted, or until all the branchlets or peduncles are reduced to single internodes, or pedicels destitute of leaves, bracts, or bractlets, when no further de- velopment can take place. Such cases enable us to study the deter- minate inflorescence to advantage, and to follow the successive steps of the ramification by direct observation. 404. A Cymule ( Cfymula) is a diminutive cyme, or a branch or cluster of a compound cyme. FIG. 330. Definite inflorescence imitating a raceme. DETERMINATE INFLORESCENCE. 219 405. The Fascicle is a very compact cyme, with upright or ap- pressed branches ; as in the Sweet "William. 406. A Glomcmle is a cyme condensed into a kind of head. It is to the cyme what the head is to the corymb or umbel. 407. There are several abnormal modifications of definite inflo- rescence, arising from irregular development, or the suppression of parts, such as the non-appearance sometimes of the central flower, or often of one of the lateral branches at each division ; as in the ultimate ramifications of Fig. 331, where one of the lateral pedicels is wanting. When this deviation is completely manifested, that is, when one of the side branches regularly fails, the cyme is apparently converted into a kind of one-sided raceme, and the flowers seem to expand from below upwards, or centripetally. The diagram, Fig. 332, when compared with Fig. 331, explains this anomaly. The place of the axillary branch which fails to develop at each ramifica- tion is indicated by the dotted lines. Cases like this occur in several Hypericums, and in some other opposite-leaved plants. An analogous case oc- curs in many alternate-leaved plants ; where the stem, being terminated by a flower, is con- tinued by a branch from the axil of the uppermost leaf or bract ; this, bearing a flower, 332 333 is similarly prolonged by a secondary branch ; that by a third, and so on ; as is shown in the diagram, Fig. 333. Such forms of inflo- FIG. 331. The open, progressively developed cyme of Alsine Michauxii. FIG. 332, 333. Plan of two modifications of helicoid cymes or false racemes. 220 THE INFLORESCENCE. rescence, which Ave may observe in Drosera, Sedum, and Hounds- tongue, imitate the raceme so nearly, that they have commonly been considered as of that kind. They are distinguishable, however, by the position of the flowers opposite the leaf or bract, or at least out of its axil ; while in the raceme, and in every modification of cen- tripetal inflorescence, the flowers necessarily spring from the axils. But if the bracts disappear, as they commonly do in the Forget-me- not, &c, the true nature of the inflorescence is not readily made out. The undeveloped summit is usually circinate, or coiled in a spiral manner (Fig. 219), gradually unrolling as the flowers grow and expand, and becoming straight in fruit On account of this coiled arrangement, such cymes or false racemes are said to be helicoid, or scorpioid. 408. The cyme, raceme, head, &c, as well as the one-flowered peduncle, may arise, either at the extremity of the stem or leafy branch (terminal), or in the axil of the leaves {axillary). The case of a peduncle opposite a leaf, as in the Poke, the Grape-vine, &c, is just that illustrated in Fig. 333, except that in these cases the peduncles bear a cluster of flowers instead of a single one. The tendrils of the Vine (Fig. 1G1) occupy the same position, and are of the same nature. In a growing Grape-vine, it is evident that the uppermost tendril really terminates the stem ; and that the latter is continued by the growth of the axillary bud, situated between the petiole and the peduncle ; the branch thus formed, assuming the direction of the main stem, and appearing to be its prolongation, throws the peduncle or tendril to the side opposite the leaf. 409. The extra-axillary peduncles of most species of Solanum, &c. are terminal peduncles, which have become lateral by the evolution of an axillary branch, with which the peduncle or the petiole is united for some distance. Such peduncles sometimes come from extra-axillary accessory buds (169). 410. In the Linden (Fig. 742) the peduncle appears to spring from the middle of a peculiar foliaceous bract. But this is rather a bractlet, inserted on the middle of the peduncle, and decurrent down to its base. 411. A peduncle which arises from the stem at or beneath the surface of the ground, as in Bloodroot, the Primrose, the so-called stemless Violets, &c, is called a radical peduncle, or a Scape. 412. A combination of the two classes of inflorescence is not un- usual, the general axis developing in one way, but the separate THE FLOWER. 221' flower-clusters in the other. Thus the heads of the Sunflower and of all the so-called compound flowers (394) are centripetal, the flowers expanding regularly from the margin or circumference to the centre ; while the branches that bear the heads ai-e developed in the centrifugal mode, the central heads being earliest to come into blos- som. This is exactly reversed in all Labiatre (plants of the Mint tribe) ; where the stem grows on indefinitely, producing axillary clusters in the form of a general raceme or spike, which blossoms from below upwards ; while the flowers of each cluster form a cyme, and expand in the centrifugal manner. These cymes, or cymules (404), are usually close and compact, and being situated one in each axil of the opposite leaves, the two together frequently form a clus- ter which surrounds the stem, like a whorl or verticil (as in the Catnip and Horehound) : hence such flowers are often said to be whorled or I'erticillate, which is not really the case, as they evidently all spring from the axils of the two leaves. Tho apparent verticil of this kind is sometimes termed a Verticillaster. 413. True whorled flowers occur only in some plants with whorled leaves, as in Hippuris and the Water Milfoil. CHAPTER IX. OP THE FLOWER. Sect. I. Its Organs, or Component Parts. 414. Having glanced at the circumstances which attend and con- trol the production of flowers, and considered the laws which govern their arrangement, we have next to inquire what the flower is com- posed of. 415. The Flower (117) assumes an endless variety of forms in different species, so that it is very difficult properly to define it. The name was earliest applied, as it is still in popular language generally applied, to the delicate and gayly colored leaves or petals, so different from the sober green of the foliage. But the petals, and all these bright hues, are entirely wanting in many flowers, while ordinary leaves sometimes assume the brilliant coloring of the 19* 222 THE FLOWKU. blossom The stamens and pistils are the characteristic organs of the flower ; hut sometimes one or the other of these disappear from 334 a particular flower, and both are absent from full double Roses, Camellias, &c, in which we have only a regular rosette of delicate leaves. This, however, is an unnatural state, the conse- quence of protracted cultivation. 416. The flower consists of the organs of re- production of a Phamogamous plant (114), and their envelopes. A complete flower consists of the essential organs of reproduction (viz. stamens and pistils), surrounded by two sets of leaves or envelopes which protect them. The latter are of course exterior or lower than the former, which in the bud they enclose. 417. The Floral Envelopes, then, are of two sorts, and occupy two circles, one above or Those of the lower circle, the exterior envelope in the flower-bud, form the Calyx : they commonly exhibit the green color and have much the appear- ance of ordinary leaves. Those of the inner circle, which are commonly of a more delicate texture and brighter color, and form the most showy part of the . blossom, compose the Corolla. The /\ 11 v\) \\ \ || several parts or leaves of the corolla are W Wilt called Petals : and the leaves of the 3iS calyx take the corresponding name of Sepals. One of the five sepals of the flower represented in Fig. 334 is separately shown in Fig. 336 ; and one of the petals in Fig. 337. The calyx and corolla, taken together, or the whole floral envelopes, whatever they may con- sist of, are sometimes called the Perianth (Periantkium or Peri- goniuni). 418. The Essential Organs of the flower are likewise of two kinds, and occupy two circles or rows, one within the other. The first of within the other. FIG. 334. The complete flower of a Crassula. 335. Diagram of its cross-section in the bud, showing the relative position of its parts. The five pieces of the exterior circle are sections of the sepals ; the next, of the petals ; the third, of the stamens through their anthers ; the in- nermost, of the five pistils. FIG. 336. A sepal ; 337, a petal ; 338, a stamen ; and 339, a pistil from the flower repre- sented in Fig. 334. ITS ORGANS OR TARTS. 223 these, those next within the petals, are the Stamens (Fig. 338). A stamen consists of a column or stalk, called the Filament (Fig. 340, a), and of a rounded hody, or case, termed the An- ther (b), filled with a powdery suhstance called Pol- len, which it discharges through one or more slits or openings. The older botanists had no general term for the stamens taken collectively, analogous to that of corolla for the entire whorl of petals, and of calyx for the whorl of sepals. A name has, however, recently been pro- posed for the staminate system of a flower, which it is occasionally convenient to use ; that of Andrcecium. 419. The remaining, or seed-bearing organs, which occupy the centre or summit of the flower, to whose protection and perfection all the other parts of the flower are in some way subservient, are termed the Pistils. To them collectively the name of Gyn^ecilm has been applied. One of them is separately shown in Fig. 339. This is seen more magnified and cut across in Fig. 342 ; and a dif- ferent one, longitudinally divided, so as to exhibit the whole length of its cavity, or cell, is represent- ed in Fig. 341. 420. A pistil is distinguished into three parts ; namely, the Ovary (Fig. 341, «), the hollow portion at the base which con- tains the Ovules, or bodies des- tined to become seeds ; the Style (b), or columnar prolongation of the apex of the ovary; and the Stigma (c), a portion of the sur- face of the style denuded of epidermis, sometimes a mere point or a small knob at the apex of the style, but often forming a single or double line running down a part of its inner face, and assum- ing a great diversity of appearance in different plants. FIG. 340. A stamen, with the anther (b) discharging its pollen : a, the filament. FIG. 341. Vertical section of a pistil, showing the interior of its ovary, a, to one side of which are attached numerous ovules, d : above is the style, b, tipped by the stigma, c. FIG. 342. A Pistil of Crassula, like that of Fig. 339, but more magnified, and cut across through the ovary, to show its cell, and the ovules it contains. At the summit of the style is Been a somewhat papillose portion, destitute of epidermis, extending a little way down the in- ner face : this is the stigma. 224 THE FLOWER. 421. All the organs of the flower are situated on, or grow out of, the apex of the flower-stalk, into which they are said, in botanical lan- guage, to be inserted, and which is called the Torus, or Receptacle. This is the axis of the flower, to which the floral organs are attached (just as leaves are to the stem) ; the calyx at its very base ; the petals just within or above the calyx ; the stamens just within the petals ; and the pistils within or above the stamens (Fig. 343). d c 422. Such is the struct- ure of a complete and regu- lar flower ; which we take as the type, or standard of comparison. The calyx and corolla are termed pro- tecting organs. In the bud, they envelope the other parts : the calyx sometimes forms a covering even for the fruit ; and when it retains its leaf-like texture and color, it as- similates the sap of the plant with the evolution of oxygen gas, in the same manner as do true leaves : the corolla elaborates honey or other secretions, for the nourishment, as is supposed, of the stamens and pistils. Neither the calyx nor corolla is essential to a flower, one or both being not unfrequently wanting. The stamens and pis- tils are, however, essential organs, since both are necessary to the production of seed. But even these are not always both present in the very same flower ; as will be seen when we come to notice the diverse forms which the blossom assumes, and to compare them with our pattern flower. Sect. II. The Theoretical Structure or General Mor- phology of the Flower. 423. To obtain at the outset a correct idea of the flower, it is needful here to consider the relation which its organs sustain to the organs of vegetation. Taking the blossom as a whole, we have recognized, in the chapter on Inflorescence (377), the identity of flower-buds and leaf-buds as to situation, &c. Flowers, consequently, FIG. 343. Parts of the flower of a Stonecrop, Sedum ternatum, two of each sort, and the receptacle, displayed : a, sepal : 6, petal : c, stamen : d, pistil. ITS THEORETICAL STRUCTURE. 225 are at least analogous to branches, and the leaves of the flower are analogous to ordinary leaves. 424 But the question which now arises is, whether the leaves of the stem and the leaves and the more peculiar organs of the flower are not homologous parts, that is, parts of the same fundamental nature, although developed in different shapes that they may sub- serve different offices in the vegetable economy ; — just as the arm of man, the fore-leg of quadrupeds, the wing-like fore-leg of the bat, the true wing of birds, and even the pectoral fin of fishes, all repre- sent one and the same organ, although developed under widely dif- ferent forms and subservient to more or less different ends. The plant continues for a considerable time to produce buds which de- velop into branches. At length it produces buds which expand into blossoms. Is there an entirely new system introduced when flowers appear ? Are the blossoms formed upon such a different plan, that the general laws of vegetation, which have sufficed for the interpre- tation of all the phenomena up to the inflorescence, are to afford no further clew ? Or, on the contrary, now that peculiar results are to be attained, are the simple and plastic organs of vegetation — the stem and leaves — developed in new and peculiar forms for the ac- complishment of these new ends ? The latter, doubtless, is the coi'- rect view. The plant does not produce essentially new kinds of organs to fulfil the new conditions, but adopts and. adapts the old. Notwithstanding these new conditions and the successively increas- ing difference in appearance, the fundamental laws of vegetation may be traced from the leafy branch into and through the flower. That is, the parts of the blossom are homologous with leaves, are leaves in other forms than that of foliage. 425. The student will have observed, that in vegetation no new organs are introduced to fulfil any particular condition, but the com- mon elements, the root, stem, and leaves, are developed in peculiar and fitting forms to subserve each special purpose. Thus, the same organ which constitutes the stem of an herb, or the trunk of a tree, we recognize in the trailing vine, or the twiner, spirally climbing other stems, in the straw of "Wheat and other Grasses, in the colum- nar trunk of the Palm, in the flattened and jointed Opuntia, or Prickly Pear, and in the rounded, lump-like body of the Melon- Cactus. So, also, branches harden into spines in the Thorn, or, by an opposite change, become flexible and attenuated tendrils in the Vine, and runners in the Strawberry ; or, when developed under 226 THE FLOWER. ground, they assume the aspect of creeping roots, and sometimes form thickened rootstalks, as in the Calamus and Solomon's Seal, or tubers, as in the Potato. But the type is readily seen through these disguises. They are all mere modifications of the stem. The leaves, as we have already seen, appear under a still greater variety of forms, some of them as "widely different from the common type of foliage as can be imagined ; such, for example, as the thickened and obese leaves of the Mesembryanthemums ; the intense scarlet or crimson floral leaves of the Euchroma, or Painted-Cup, of the Poinsettia of our conservatories, and of several Mexican Sages ; the tendrils of the Pea tribe ; the pitchers of Sarracenia (Fig- 300), and also those of Nepenthes (Fig. 301), which are leaf, tendril, and pitcher combined. The leaves also appear under very different aspects in the same individual plant, according to the purposes they are intended to subserve. The first pair of leaves, or cotyledons, when gorged with nutritive matter for the supply of the earliest wants of the embryo plant, as in the Almond, Bean, Pea, &c. (Fig. 108-120), would seem to be peculiar organs. But in some of these cases, when they have discharged this special office in ger- mination, by yielding to the young plant the store of nourishment with which they are laden, they imperfectly assume the color and appearance of foliage ; while in other cases, as in the Convolvulus (Fig. 123) and the Maple (Fig. 104), they are green and foliaceous from the first. As the stem develops, the successive leaves vary in form or size, according to the varying vigor of vegetation. In our trees, we trace the last leaves of the season into bud-scales ; and in the returning spring we may often trace the scales of opening buds through intermediate states back again into true leaves (161). 426. The analogies of vegetation would therefore lead us to ex- pect, that in flowering the leaves would be wrought into new forms, to subserve peculiar purposes. In the chapter on Inflorescence, we have already learned that the arrangement and situation of flowers upon the stem conform to this idea. In this respect, flowers are absolutely like branches. The aspect of the floral envelopes favors the same view. We plainly discern the leaf in the calyx, and again, more delicate and refined, in the petals. In numberless in- stances, we find a regular transition from ordinary leaves into sepals, and from sepals into petals. And, while even the petals are occa- sionally green and herbaceous, the undoubted foliage sometimes assumes a delicate texture and the brightest hues (425). The per- ITS THEORETICAL STRUCTURE. 227 feet gradation of leaves or bracts into sepals is extremely common. The transition of sepals into petals is exemplified in almost every case where there are more than two rows of floral envelopes ; as in the Magnolia, and especially in the White Water-Lily, various kinds of Cactus, the Ulicium, or Star- Anise of the Southern States, and the Calycanthus, or Carolina Allspice, which present several series of floral envelopes, all nearly alike in color, texture, and shape ; but how many of the innermost are to be called petals, and how the re- mainder are to be divided between sepals and bracts, is entirely a matter of arbitrary opinion. In fact, the only real difference be- tween the calyx and corolla is, that the former is the outer, and the latter an inner series of floral envelopes. Sometimes the gradation extends one step farther, and exhibits an evident transition of petals into stamens ; showing that these are of the same fundamental nature as the floral envelopes, which are manifestly traceable back to leaves. The White Water-Lily (Fig. 344) exhibits this latter transition, as evi- dently as it does that of sepals into petals. Here the petals occupy sev- eral whorls ; and while the exterior are nearly undis- tinguishahle from the calyx, the in- ner are reduced in- to organs which are neither well-formed petals nor stamens, but intermediate be- tween the two. They are merely petals of a smaller size, with their summits contracted and transformed into imperfect anthers, containing a few grains of pollen : those of the series next within are more reduced in size, and bear perfect anthers at the apex ; and a still further reduction of the lower part of the petal completes the transition into stamens of ordinary appearance. 427. By regular gradations, therefore, the leaf may be traced to FIG. 344. A sepal, petals, bodies intermediate between petals and stamens, and true sta- mens, of the White Water-Lily. 228 THE FLOWER. the petal and the stamen. But we could not expect to meet with intermediate states between a stamen and a pistil, except as a mon- strosity. The same organ could not fulfil such antagonistic offices. Nevertheless, stamens changing into pistils are occasionally found in monstrous blossoms. Cases of the kind are not very rare in Wil- lows, where anthers are found either half changed or else perfectly transformed into pistils, and bearing ovules instead of pollen. In gardens some stamens of the common Poppy have been found changed into perfect pistils, and imperfect attempts of the kind are more frequently to be detected in the large Oriental Poppy. Two Apple-trees in Ashburnham, Massachusetts, have long been known, which annually produce flowers in which the petals are replaced by five small foliaceous bodies, resembling sepals, and in place of sta- mens there are ten separate and accessory pistils, inserted on the throat of the calyx. 428. This transformation of one organ into another is called met- amorphosis. Assuming green foliage to be the natural state of leaves, the sepals and petals are said to be transformed or metamor- phosed leaves ; and the stamens and pistils are still more metamor- phosed, losing as they ordinarily do all appearance of leaves. Still, if these organs be, as it were, leaves developed in peculiar states, under the controlling agency of a power which has overborne the ordinary forces of vegetation, they must always have a tendency to 3 4 5 346 develop in their primitive form, when the causes that govern the production of blossoms are interfered with during their formation. They may then reverse the spell, and revert into some organ below them in the series, as from stamens into petals, or pass at once into the state of ordinary leaves. That is, organs which from their position should be stamens or pistils may develop as petals or floral leaves, or else may revert at once to the state of ordinary leaves. Such cases of retrograde metamorphosis frequently occur in cultivated flowers. 429. Thus we often meet with the actual reconversion of what FIG. 345. A small leaf in place of a pistil from the centre of a flower of the double Cherry. 346. An organ intermediate between a leaf and a pistil, from a similar flower. FIG. 347. Leaflet of a Brvophylluni, developing buds along its margins. ITS THEORETICAL STRUCTURE. 229 should be a pistil into a leaf in the double Garden Cherry, either completely (Fig. 345), or else incompletely, so that the resulting organ (as in Fig. 346) is something intermediate between the two. The change of tvhat should be stamens into petals is of common oc- currence in what are called double and semi-double flowers of the gardens ; as in Roses, Camellias, Carnations, &c. When such flow- ers have many stamens, these disappear as the supernumerary petals increase in number ; and the various bodies that may be often ob- served, intermediate between perfect stamens (if any remain) and the outer row of petals, — from imperfect petals, Avith a small lamina tapering into a slender stalk, to those which bear a small distorted lamina on one side and a half-formed anther on the other, — plainly reveal the nature of the transformation that has taken place. Car- ried a step farther, the pistils likewise disappear, to be replaced by a rosette of petals, as in fully double Buttercups. 430. In full double Buttercups we may often notice a tendency in the inner petals to turn green, that is, to retro- grade still farther into foli- aceous organs. And there is a monstrous state of the Strawberry blossom, well known in Europe, in which all the floral organs revert into green sepals, or imper- fect leaves. Fig. 348 ex- hibits a similar retrograde metamorphosis in a flower of the "White Clover, where the calyx, pistil, &c. are still recognizable, although partially transformed into leaves. And the ovary, which has opened down one side, bears on each edge a number of small and imperfect leaves ; much as the ordinary leaves, or rather leaflets, of Bryophyllum are apt to develop rudimentary tufts of leaves, or leaf-buds, on their margins (Fig. 347), which may grow into little plantlets, by which the species is often propagated. This retrograde metamorphosis of FIG. 348. A flower of the common White Clover reverting to a leafy branch; after Turpin. 20 230 THE FLOWER. a whole blossom into foliaceous parts has been termed chlorosis, from the green color thus assumed. 431. A somewhat different proof that the blossom is a sort of branch, and its parts leaves, is occasionally furnished by monstrous flowers in the production of a leafy branch from the centre of a flower, or of one flower out of the centre of another (as rose-buds out of roses). Here the receptacle or axis of the flower resumes the ordinary vegetative growth, as in Fig. 349, 350. In wet and warm springs, some of the flower- buds of the Pear and Apple are occasion- ally forced into vege- tation, so as com- pletely to break up the flower and change it into an ordinary leafy branch. This proves that the recep- tacle of a flower is of the nature of the stem. 432. An analogous kind of monstrosity, viz. the development of buds — either into leafy branches or into blossoms (Fig. 351) — in the axils of petals, or even of stamens or pistils, fur- nishes additional evidence that these bodies are of the nature of leaves ; for, whatever bears a bud or branch in its axil must represent a leaf. 433. The irresistible conclusion from all such evidence is, that the flower is one of the forms — the ultimate form — under which branches appear ; that the leaves of the stem, the leaves or petals of the flower, and even the stamens and pistils, are all forms of a common FIG. S49. Retrograde metamorphosis of a flower of the Fraxinella of the gardens, from Lindley "s Theory of Horticulture ; an internode elongated just above the stamens, and bearing a whorl of green leaves. FIG. 350. A monstrous pear, prolonged into a leafy branch ; from Bonnet. FIG. 351. A flower of False Bittersweet (Celastrus scandens), producing other flowers in the axils of the petals ; from Turpin. ITS THEORETICAL STRUCTURE. 231 type, only differing in their special development. And it may be added, that in an early stage of development they all appear nearly alike. That which, under the ordinary laws of vegetation, would have developed as a leafy branch, here developes as a flower ; its several organs appearing under forms, some of them slightly, and others extremely, different in aspect and in office from the foliage. But they all have a common nature and a common origin, or, in other words, are homologous parts (424). 434. Now, as we have no general name to comprehend all those organs which, as foliage, bud-scales, bracts, sepals, petals, stamens, &c, successively spring from the ascending axis or stem, having ascer- tained their essential identity, we naturally take some one of them as the type, and view the others as modifications or metamorphoses of it. The leaf is the form which earliest appears, and is the most general of all the organs of the vegetable ; it is the form which is indispensable to normal vegetation, since in it, as we have seen, as- similation is effected, and all organic matter is produced ; it is the form into which all the floral organs may sometimes be traced back by numerous gradations, and to which they are liable to revert when flowering is disturbed and the vegetative forces again prevail. Hence the leaf may be properly assumed as the type or pattern, to which all the others are to be referred. When, therefore, the floral organs are called modified or metamorphosed leaves, it is not to be supposed that a petal has ever actually been a green leaf, and has subsequently assumed a more delicate texture and hue, or that sta- mens and pistils have previously existed in the state of foliage ; but only that what is fundamentally one and the same organ develops, in the progressive evolution of the plant, under each or any of these various forms. When the individual organ has developed, its destiny is fixed. 435. The theory of vegetable morphology may be expressed in other and more hypothetical or transcendental forms. We have preferred to enunciate it in the simplest and most general terms. But, under whatever particular formula expressed, its adoption has not only greatly simplified, but has thrown a flood of light over the whole of Structural Botany, and has consequently placed the whole logic of Systematic Botany upon a new and philosophical basis. Our restricted limits will not allow us to trace its historical develop- ment. Suffice it to say, that the idea of the essential identity of the floral organs and the leaves was distinctly propounded by Lin- 232 THE FLOWER. nteus,* about the middle of the last century. It was newly taught by Caspar Frederic Wolff, about twenty years later, and again, after the lapse of nearly twenty years more, by the celebrated Goethe, who was entirely ignorant, as were his scientific contemporaries, of what Linnreus and Wolff had written on the subject. Goethe's curious and really scientific treatise was as completely forgotten or overlooked as the significant hints of Linnaeus had been. In ad- vance of the science of the day, and more or less encumbered with hypothetical speculations, none of these writings appear to have ex- erted any appreciable influence over the progress of the science, until it had reached a point, early in the present century, when the nearly simultaneous generalizations of several botanists, following different clews, were leading to the same conclusions. Ignorant of the writings of Goethe and Wolff, De Candolle was the first to de- velop, from an independent and original point of view, the idea of symmetry in the flower ; that the plan, or type, of the blossom is regular and symmetrical, but that this symmetry is more or less in- terfered with, modified, or disguised by secondary influences, such as suppressions, alterations, or irregularities, giving rise to the greatest diversity of forms. The reason of the prevailing symmetrical ar- rangement of parts in the blossom has only recently been made apparent, in the investigation of phyllotaxis (236) ; from which it appears that the general arrangement of the leaves upon the stem is carried out in the flower. Sect. III. The Symmetry of the Flower. 436. A Symmetrical Flower is one which has an equal number of parts in each circle or whorl of organs ; as, for example, in Fig. 334, where there are five sepals, five petals, five stamens, and five pistils. It is not less symmetrical, although less simple, when there are two or more circles of the same kind of organ ; as in Sedum (Fig. 361), where there are two sets of stamens, five in each; in the Barberry, where there are two or more sets of sepals, two of petals, and two of stamens, three in each set, &e. A complete floioer * " Principium florum etjbliorum idem est. Principium gemmarum et folio- rum idem est. Gemma constat folioram rudimentis. Pcrianthium sit ex con- iiatis foliorum rudimentis," etc. Philosophia Botanica, p. 301. ITS SYMMETRY. 233 of floral stamens (as already defined, 416) is one that possesses both sorts envelopes, calyx and corolla, and both essential organs, viz. and pistils. 437. The simplest possible complete and symmetrical flower would be one with the ca- lyx of a single sepal, a corolla of a single petal, a single stamen, and a single pistil ; as in the annexed diagram (Fig. 352), which represents the elements of a simple stem (Fig. 157), ter- minated by an equally simple flower. Each constituent of the blossom represents a phyton (1G3), with its stem part reduced to a mini- mum, and its leaf part developed in a peculiar way, according to the rank it sustains and the office it is to fulfil. That there are short inter- nodes between consecutive organs in the flower is usually apparent on minute inspection of its axis, or receptacle ; and some of them are con- spicuously prolonged in certain cases. But they are commonly so short that the organs are brought into juxtaposition, just as in a leaf- bud, and the higher or later-formed parts are interior or enclosed by the lower. 438. Perhaps the exact case of a flower at once so complete and so simple is not to be met with, the organs of the flower, or some of them, being generally multiplied. Thus we find a circle or whorl of each kind of organ, and often two or three circles, or a still larger and apparently indefinite number of parts. In fact, the floral organs usually occur in twos, threes, fours, or fives ; and the same number is apt to prevail throughout the several circles of the flower, which therefore displays a sym- 352 metrical arrangement, or a manifest tendency towards it* * Terms expressive of the number of parts which compose each whorl or kind of organ — which are sometimes very convenient to use — arc formed of FIG. 352. Diagram of a plant, with a distichous arrangement of the phytons, carried through the complete flower, of the simplest kind, consisting of, a, a sepal j b, a petal j c, a stamen ; and d, a pistil : br is the bract or uppermost proper leaf. 20* 234 THE FLOWER. 430. Having already noticed the symmetrical arrangement of the foliage (236-251), and remarked the transition of ordinary leaves into those of the blossom (426), we naturally seek to bring the two under the same general laws, and look upon each floral whorl as answering ei- ther to a cycle of alter- nate leaves with their 33i respective internodes undeveloped, or to a pair or verticil of opposite or verticillate leaves. Thus, the simplest com- bination, where the organs are dimerous, or in twos, may be compared with the alternate two- ranked arrangement (238), the calyx, the corolla, stamens, &c. each consisting of one cycle of two elements ; or else with the case of opposite leaves (250), when each set would answer to a pair of leaves. So, likewise, the organs of a trimerous flower (viz. one with its parts in threes, as in Fig. 353) may be taken either as cycles of alternate leaves of the tristichous mode (239), with the axis shortened, which would throw the parts into successive whorls of threes, or else as proper verticils of three leaves ; while those of a pentamerous or quinary flower (with the parts in fives, as in Fig. 354) would answer to the cycles of the § arrangement (240) of alternate leaves, or to proper five-leaved verticils. So the whorls of a tetra- merous flower are to be compared with the case of decussating op- the Greek numerals combined with fiepos, a part. Thus a flower with only one organ of each kind, as in the diagram, Fig. 352, is mo/wmerous : a flower or a whorl of two organs is dimerous (Fig. 373) ; of three (as in Fig. 353), trimerous ; of four, tetramerous (Fig. 405) ; of five (as in Fig. 334), pentamerous ; of six, hex- amcrous ; of ten, ckeamcrous, &c. These words arc often printed with figures, as 2-merous, S-merous, A-merous, 5-merous, and so on. FIG. 353. Parts of a symmetrical trimerous flower (Tillsea muscosa) : a, calyx ; b, corolla ; c, stamens ; d. pistils. FIG. 354. Ideal plan of a plant, with the simple stem terminated by a symmetrical penta- merous flower ; the different sets of organs separated to some distance from each other, to show the relative situation of the parts ; one of each, namely, o, a sepal, 6, a petal, c, a stamen, and d, a pistil, also shown, enlarged. ALTERNATION OF THE FLORAL ORGANS. 235 posite leaves, combined two by two, or with quaternary verticillate leaves (251) ; either of which would give sets of parts in fours. 440. The Alternation of the Floral Organs. We learn from obser- vation that, as a general rule, the parts of the successive circles of the flower alternate with each other. The five petals of the flower represented in Fig. 334, for ex- ample, are not opposed to the five sepals (that is, situated directly above or before them), but alter- nate with them, that is, or stand over the intervals between them ; the five stamens in like manner al- ternate with the petals, and the five pistils with the stamens, as is shown in the diagram, Fig. 335. The same is the case in Fig. 353, the several organs of a flower Avith its parts in threes ; and in fact this is the rule, the few exceptions to which have to be separately accounted for. 441. This comports with the more usual phyllotaxis in opposite and verticillate leaves, where the successive pairs decussate, or cross each other at right angles (251), or the leaves of one verticil several- ly correspond to the intervals of that underneath, making twice as many vertical ranks as there are parts in the whorl. The alternation of the floral organs is therefore most readily explained on the assump- tion that the several circles are true decussating verticils. But the inspection of a flower-bud with the parts imbricated in aestivation (494) shows that the several members of the same set do not origi- nate exactly in the same plane. The five petals, for example, in the cross-section of the pentamerous blossom shown in Fig. 335 (and the same arrangement is still more frequently seen in the calyx), are so situated, that two are exterior in the bud, and therefore in- serted lower on the axis than the rest, the third is intermediate, and two others are entirely interior, or inserted higher than the rest. In fact, they exactly correspond with a cycle of alternate leaves of the quincuncial or five-ranked arrangement, on an extremely abbreviated axis, or on a horizontal plane, as is at once seen by comparing the ground plan, Fig. 335, with Fig. 206. Compare also Fig. 355 with Fig. 203. Also, when the parts are in fours, two are almost always exterior in the bud, and two interior. Moreover, whenever the floral envelopes, or the stamens or pistils, are more numerous, so as to occupy several rows, the spiral disposition is the more manifest. It is most natural, accordingly, to assume that the calyx, corolla, FIG. 355. Cross-section of the flower-bud of Fig. 353, to show the alternation of parts. 236 THE FLOWER. stamens, &c. of a pentamerous flower are each a depressed spiral or cycle of the § mode of phyllotaxis, and those of the trimerons flower are similar spirals of the £ mode. But then the parts of the suc- cessive cycles should be superposed, or placed directly before each other on the depressed axis, as leaves are ; whereas, on the contrary, they almost always alternate with each other in the flower. 442. To reconcile this alternation with the laws of phyllotaxis in alternate leaves, Prof. Adrien de Jussieu has advanced an ingenious hypothesis. lie assumes the T 5 3 spiral arrangement as the basis of the floral structure both of the trimerous and pentamerous flower, (at least when the envelopes are imbricated in the bud,) this being the one that brings the successive parts most nearly into alternation, either in threes or in fives ; as will readily be observed on inspection of the tabular projection of that mode, given on page 139. The dif- ference between the position of parts in regular alternation, Avhether in threes or fives, and that assigned by an accurate spiral projection of the T 5 5 mode, is very slight as respects most of the organs, and in none does the deviation exceed one thirteenth of the circumference ; — a quantity which becomes nearly insignificant on an axis so small as that of most flowers. Moreover, if the interior organs of a regular and symmetrical flower were thus to originate in the bud nearly in alternation with those that precede them, they would almost necessa- rily be crowded a little, as they develop, into the position of least pres- sure, and thus fall into these intervals with all the exactness that is actually found in nature. For in living bodies, endowed as they are with plasticity and a certain power of adaptation to circumstances, the positions assumed are not mathematically accurate ; and the effect of unequal pressure in the bud in throwing the smaller parts more or less out of their normal position may be observed in almost any irregular flower. Moreover, in all the forms of phyllotaxis from T 5 g- onwards, it is doubtful whether what we term vertical ranks are exactly superposed. In tracing them upward to some extent, we perceive indications of a curviserial arrangement, where the superposition is continually approximated, but is never exactly at- tained (248). Lestibudois* has revived the older hypothesis of Jussieu, and others ; viz. that a second spiral is introduced with the petals and continued in the pistils. And Schimper and Braun im- agine a change of half the angular divergence (prosenthesis) to occur * In Annates des Sciences Naturelles, ser. 4, Vol. 2, p. 226. POSITION IN RESPECT TO THE BRACT AND AXIS. 237 in passing from one cycle to the next ; — which is rather describing the anomaly in other words than explaining it. 443. Whether we regard the floral circles as decussating verticils, or as cycles of alternate leaves in some way altered as to their suc- cession, we cannot fail to discern an end attained by such arrange- ment, namely, a disposition of parts which secures the greatest econ- omy of space on an abbreviated axis, and the greatest freedom from mutual pressure. 444. Position of the Flower as respects the Axis and subtending Bract. All axillary flowers are situated between a leaf and the stem, or, which is the same thing, between a bract and the axis of inflores- cence. These two fixed points enable us to indicate the relative position of the parts of the floral circles with precision. That part of the flower which lies next the leaf or bract from whose axil it arises is said to be anterior, or inferior (lower) : that which is dia- metrically opposite or next the axis is posterior, or superior (upper).* It is important to notice the relative position of parts in this re- spect. This is shown in a proper diagram by drawing a section of the bract in its true position under the section of the flower- bud, as in Fig. 358 : the position of the axis is necessarily dia- metrically opposite, and its section is sometimes indicated by a dot or small circle. In an axillary flower with the parts hi fours, one of * As if these were not terms enough, sometimes the organ, or side of the flower, which looks towards the bract, is likewise called exterior, and the organ or side next the axis, interior ; but these terms should be kept to designate the relative position of the members of the floral circles in aestivation (494). FIG. 356. Diagram of a Cruciferous flower (Erysimum) ; a, the axis of inflorescence. (The bract is abortive in this, as in most plants of this family.) FIG. 357. Diagram of a flower of a Rhus, with the axis, a, and the bract, b, to show the relative position of parts. FIG. 358. Diagram of a flower of the Pulse tribe : a, the axis, and 0, the bract. 238 THE FLOWER. the sepals will be anterior, one posterior, and two lateral, or right and left ; as in the annexed diagram of a Cruciferous blossom (Fig. 356) ; while the petals, alternating with the sepals, consist of an anterior and a posterior pair ; and the stamens, again, stand before the sepals. An axillary flower of five parts will have either one sepal superior or posterior and two inferior or anterior (as in Rhus, Fig. 357), or else, vice versa, one inferior and two superior, as in Papilionaceous flowers (Fig. 358) : in both cases the two remaining sepals are lateral. The petals will consequently stand one superior, two inferior, and two lateral, in the last-named case ; and one in- ferior, two superior, and two lateral, in the former. In terminal flowers (401), the position of parts in respect to the uppermost leaves or bracts should be noted. Sect. IV. The Various Modifications of the Flower. 445. The complete and symmetrical flowers, with all their organs in the most normal state, that have now been considered, will serve as the type or pattern, with which Ave may compare the almost num- berless variety of forms which blossoms exhibit, and note the char- acter of the differences observed. We proceed upon the supposi- tion, that all flowers are formed upon a common plan, — a plan essentially the same as that of the stem or branch, of which the flower is a modified continuation, — so that in the flower Ave are to expect no organs other than those that, Avhatever their form and office, ansAver either to the axis or to the leaves ; so that the differ- ences between one flower and another are to be explained as cir- cumstantial variations of one fundamental plan, — variations for the most part analogous to those Avhich occur in the organs of vegeta- tion themselves. Having assumed the type which represents our conception of the most complete, and at the same time the simplest floAver, Ave apply it to all the cases Avhich present themselves, and especially to those blossoms in Avhich the structure and symmetry are masked or obscured ; Avhere, like the disenchanting spear of Ithuriel, its application at once reveals the real character of the most disguised and complicated forms of structure. 446. Our pattern floAver consists of four circles, one of each kind of floral organ, and of an equal number of parts, successively alternat- ing Avith one another. It is complete, having both calyx and corolla, ITS VARIOUS MODIFICATIONS. 239 as well as stamens and pistils (41 G) ; symmetrical, having an equal number of parts in the successive whorls (43 G) ; regular, in having the different members of each circle all alike in size and shape ; it has but one circle of the same kind of organs ; and, moreover, all the parts are distinct or unconnected, so as to exhibit their separate origin from the axis or receptacle of the flower. This type may be presented under either of the four numerical forms which have been illustrated. That is, its circles may consist of parts in twos (when it is binary or dimerous), threes (ternary or trimerous), fours (qua- ternary or tetramerous), or fives (quinary or pentamerous). The first of these is the least common; the trimerous and the pentame- rous far the most so. The last is restricted to Dicotyledonous plants, where five is the prevailing number ; while the trimerous flower largely prevails in Monocotyledonous plants, although by no means wanting in the Dicotyledonous class, from which Fig. 353 is taken. 447. The principal deviations from the perfectly normal or pattern flower may be classified as follows. They arise, either from, — 1st. The production of additional circles of one or more of the floral organs (regular multiplication or augmentation) ; 2d. The production of a pair or a cluster of organs where there should normally be but one, that is, the multiplication of an organ by division (abnormal multiplication, also termed deduplication or chorisis) ; 3d. The anteposition (or opposition, instead of alternation) of the parts of successive circles ; 4th. The union of the members of the same circle (coalescence) ; 5th. The union of adjacent parts of different circles (adnation) ; Gth. The unequal growth or unequal union of different parts of the same circle [irregularity) ; or, 7th. The non-production or abortion of some parts of a circle, or of one or more complete circles (suppression or abortion). 8th. To which may be added, the abnormal development of the receptacle or axis of the flower. 448. Some of these deviations interfere with the symmetrical structure of the flower ; others merely render it irregular, or dis- guise the real origin or the real number of parts. These deviations, moreover, are seldom single ; but two, three, or more of the kinds fre- quently co-exist, so as to realize almost every conceivable variation. 449. Several of these kinds of deviation may often be observed 240 THE FLOWER. $$to o even in the same natural family of plants, where it cannot be doubt- ed that the blossoms are constructed upon a common plan in all the species. Even in the family Crassulaceae, for example, where the flowers are remarkably symmetrical, and from which our pattern flowers, Fig. 334 and 353, are derived, a considerable number of these di- versities are to be met with. In Crassula, we have the completely symmetrical and simple pentamerous flower (Fig. 359, 3G0), viz. with a calyx of five sepals, a corolla of five petals alter- nate with the former, an andrcecium (418) of five stamens alternating with the petals, and a gynsecium (419) of five pistils, which are alter- nate with the stamens ; and all the parts are regular and symmetrical, and also distinct and free from each other ; except that the sepals are somewhat united at the base, and the petals and 360 stamens slightly connected with the inside of the calyx, instead of arising directly from the recep- tacle or axis, just beneath the pistils. Five is the prevailing or normal number in this family. Nevertheless, in the related genus Tillrea, most of the species, like ours of the United States, have their parts in fours, but are otherwise similar, and one common European species has its parts in threes (Fig. 353) ; that is, one or two members are left out of each circle, which of course does not in- terfere with the symmetry of the blossom. So in the more conspic- uous genus Sedum (the Stonecrop, Live-for-ever, Orpine, &c), some species have their parts in fives ; others in fours ; and several, like our S. ter- natum, have those of the first blossom in fives, but all the rest in fours. But Sedum also illustrates the case of reg- ular augmentation (447, 1st) in its an- droecium, which consists of twice as many stamens as there are members in the other parts ; that is, an addi- 361 tional circle of stamens is introduced (Fig. 361), the members of which may be distinguished by being shorter or a little later than FIG. 359. Flower of a Crassula. 360. Cross-section of the bud. FIG. 361. Flower of a Sedum or Stonecrop. ITS VARIOUS MODIFICATIONS. 241 those of the primary circle, and by their alternation with these, which brings them directly opposite the petals. A third genus (Rochea) exhibits the same pentamerous and normal flower as Cras- sula, except that the contiguous edges of the petals slightly cohere about half their length, although a little force suffices to separate them: in another (Grammanthes, Fig. 362), the petals are firmly united into a tube for more than half their length, and so are the sepals likewise ; illustrating the fourth of the deviations above enumerated (447). Next, the allied genus Cotyledon (Fig. 363) exhibits in the same flower both this coalescence of similar parts, and an additional circle of stamens, as in Sedum. It likewise pre- sents the next order of deviations, in the union (adnation) of the base of its stamens to the base of the corolla, out of which they ap- parently arise, as is seen in Fig. 364, where the corolla is laid open and displayed. The pistils, although ordinarily exhibiting a strong tendency to unite, are perfectly distinct in all these cases, and in- deed throughout the order, with two exceptions ; one of which is seen in Penthorum, where the five ovaries (Fig. 365) are united below into a solid body, while their summits, as well as the styles, are separate. The same jdant also furnishes an example of the non- production (or supjyression) of one set of organs, that of the petals ; which, although said to exist in some specimens, are ordinarily Avant- ing altogether. Another instance of increase in the number of parts occurs in the Houseleek (Sempervivum), in which the sepals, petals, and pistils vary in different species from six to twenty, and the sta- mens from twelve to forty. 450. Some illustrations of the principal diversities of the flower, FIG. 362. Flower of Grammanthes. 363. Flower of a Cotyledon. 361. The corolla laid open, showing the two rows of stamens inserted into it. 365. The five pistils of Penthorum, united. 366. A cross-section of the same. 21 242 THE FLOWER. as classified above (447), may be drawn at random from different families of plants ; and most of the technical terms necessarily em- ployed in describing these modifications may be introduced, and explained, as we proceed. The multiplication of parts is usually in consequence of the 451. Augmentation of the Floral Circles. An increased number of circles or parts of all the floral organs occurs in the Magnolia family ; where the floral envelopes occupy three or four rows, of three leaves in each, to be divided between the calyx and corolla, while the stamens and pistils are very numerous, and compactly arranged on the elongated receptacle. Tbe Custard- Apple family, which is much like the last, has also two circles in the corolla, three petals in each, a great increase in the number of stamens, and, in our Papaw (Fig. 654), sometimes only one circle of pistils, viz. three, sometimes twice, thrice, or as many as five times that number. The Water-Lily, likewise, has all its parts augmented, the floral envelopes and the stamens especially occupying a great number of rows ; and the pistils are likewise numerous, although their number is disguised by being united into one body. "When the sepals, petals, or other parts of the flower are too numerous to be readily counted, or even exceed twelve, especially when the number is inconstant, as it commonly is in such cases, they are said to be indefinite ; and a floAver with numerous stamens is also termed polyandrous. 452. WTien such multiplication of the floral circles is perfectly regular, the number of the organs so increased is a multiple of that which forms the basis of the flower ; but this could scarcely be de- termined when the numbers are large, as in the stamens of a Butter- cup, for example, nor is there much constancy when the whorls of any organ exceed three or four. The doubling or trebling of any or all the floral circles does not interfere with the symmetry of the flower ; but it may obscure it (in the stamens and pistils especially), by the crowding of two or more circles of five members into what appears like one of ten, or two trimerous circles into what appears like one of six. The latter case occurs in most Endogenous plants. 453. The production of additional floral circles may account for most cases of increase of the normal number of organs, but not for all of them. It must, we think, be admitted that certain parts of the blossom are sometimes increased in number by the production of a double organ, or a pair or a group of organs which occupy the place of one ; namely, by what has been termed CHORISIS OR DEDUPLICATION. 243 454. CJlOl'isis Or Deduplication. The name dedoublement of Dunal, which has been translated deduplication, literally means unlining ; the original hypothesis being, that the organs in question unline, or tend to separate into two or more layers, each having the same structure. We may employ the word deduplication, in the sense of the doubling or multiplication of the number of parts, without adopting this hypothesis as to the nature of the process, which at best can well apply only to some special cases. The word chorisis (xwpto-ty, the act or state of separation or multiplication), also pro- posed by Dunal, does not involve any such assumption, and is ac- cordingly to be preferred. By regular multiplication, therefore, we mean the augmentation of the number of organs through the de- velopment of additional circles ; which does not alter the symmetry of the flower. By chorisis we denote the production of two or more organs in the place of one, in a manner analogous to the division of the blade of a leaf into a number of separate blades, or leaflets. 455. Chorisis, or the division of an organ into a pair or a cluster, may take place in two ways. In one case the parts or organs thus produced stand one before the other ; in the other case they stand side by side. The first is named transverse chorisis ; the second, collateral chorisis. Both must evidently disturb or disguise the normal symmetry of the blossom. 456. Collateral Chorisis is that in respect to which there is least doubt as to the nature of the process. We have a good example of it in the tetradynamous stamens (519) of the Mustard or Cress family (Fig. 40G). Here, in a flower with a symmetrical tetramerous calyx and corolla, we have six stamens ; of which the two lateral or shorter ones are alternate with the adjacent petals, as they normally should be, while the four are in two pairs, one pair before each remaining interval of the petals ; as is shown in the annexed diagram (Fig. 367). That is, on the anterior and on the posterior side of the flower we have two stamens where there normally should be but a single one, and where, FIG. 367. Diagram of a (tetradynamous) flower of the order Cruciferse. TIG. 368. Flower of Streptanthus hyacinthoides, from Texas (the sepals and stamens re- moved), showing a forked or double stamen in place of the anterior pair. 244 THE FLOWER. indeed, there is but one in a few plants of this family. Now it oc- casionally happens that the doubling of this stamen is, as it were, arrested before com- pletion, so that in place of two stamens we have a forked fila- ment bearing a pair of anthers ; as fre- quently happens in some species of Strep- tanthus (Fig. 368). Here the two stamens in place of one may be compared with a compound leaf of two leaflets. In the re- lated Fumitory fam- ily three stamens reg- ularly appear in the place of one. The circles of the flower are in twos through- out ; viz. there is, first, a pair of small scale-like sepals ; alternate with these, a pair of petals, which, in Dicentra, &c. (Fig. 369-371), are saccate or spurred below ; alternate and within these is a second pair of petals (Fig. 372) ; alternate with these are two clusters of three more or less united stamens, which plainly occupy the place of two single stamens. The arrangement of parts is shown in the annexed diagram (Fig. 373) ; where the lowest line indicates the subtending bract, and therefore the anterior side of the blossom; the two short lines in the same plane represent the sepals ; the two FIG. 369. Dicentra Cucullaria (Dutchman's-Breeches), with its kind of bulb, a leaf, and a scape in flower ; reduced in size. 370. A flower of the natural size. 371. The same, with the parts separated, except the sepals, one of which is seen at the base of the pistil. 372. The inner pair of petals, with their tips coherent. FIG. 373. Diagram (cross-section) of the similar flower of Adlumia. 374. One of the sta- mens increased into three by chorisis (the lower part of the common filament is cut away). CHORISIS OR DEDUPLICATION. 245 next within, the lateral and exterior petals; those alternate and within these, the inner circle of petals ; and alternate with these are the anthers of the two stamen-clusters. The centre is occupied by a section of the pistil, which consists of two united. The three sta- mens are lightly connected in Dicentra (Fig. 371) ; but in Corydalis and Adlumia there is only one strap-shaped filament on each side, which is three-forked at the tip, each fork bearing an anther (Fig. 374). We have a similar case in some Hypericums and in Elodea (Fig. 375), except that, while the floral envelopes are in fives, the circles within them are commonly in threes. The three members of the androecium are normally placed, alter- nating with the three members of the gynreciuni within, and also with three glands, which probably replace another circle of stamens. Now each real stamen is here multiplied into three, united below ; so that the Avhole compound body may be viewed as homologous with a compound trifoliolate leaf (289). If this be so, then each cluster of numerous stamens in the common St. Johns- wort may be regarded as answering to one stamen greatly multiplied in the same way, and as analogous to a sessile decompound leaf. And the same may be said of each stamen-cluster in the Linden (Fig. 383). The actual development of the cluster, from a protu- berance which in the forming flower-bud occupies the place of a single stamen, has been traced by Duchatre, Payer, &c. in this and other cases. 457. Thus far we are sustained by a clear analogy in the organs of vegetation. As the leaf frequently develops in the form of a lobed, divided, or compound leaf, — that is, as a cluster of partially or completely distinct organs from a common base, — so may the stamen, or even the pistil, become compound as it grows, and give rise to a clus- ter, instead of completing its growth as a solitary organ : and it appears that the organogeny is strikingly sim- ilar in the two cases. Nor is it very unusual for petals to become divided or deeply lobed in the same manner ; as, for example, those FIG. 375. Diagram (cross-section) of a flower of Elodea Virginica. 376. One of the three stamen-clusters, consisting of a trebled stamen, enlarged. FIG. 377. A petal of JMiguonette, enlarged. 21* 246 THK FLOWKR. of Mignonette (Fig. 377). In certain cases an analogous division ' takes place in the opposite direction, so that the parts or lobes are situated one before the other. An indication of this is also mani- fest in the petals of Mignonette, the lower part or broad claw of which is slightly extended at its summit, on each side, beyond the origin of the many-cleft limb or blade. Division in this direc- tion has been termed 458. Transverse or Vertical Chorisis. The most familiar case is that of the croivn, or small' and mostly two-lobed ap- pendage on the inside of the blade of the petals of Silene (Fig. 378) and of many other Caryo- phyllaceous plants. This is more like a case of real dedoublement or unlining, i. e. a partial sepa- ration of an inner lamella from the outer, and perhaps may be so viewed. Stamens sometimes bear a similar and more striking appendage, as in Larrea, for example (Fig. 379), and most other plants' of the Guaiacum family ; also in the 378 Dodder (Fig. 1044). Let it be noted that in all such cases the appendage occupies the inner side of the petal or stamen, and that it is commonly two-lobed. Again, before each petal of Parnassia (Fig. 381), although slightly if at all united with it, is found a body which in P. palustris is somewhat petal-like, with a considerable number of lobes, and in P. Cai'oliniana is divided almost to the base into three lobes, which look much like abortive stamens. The true stam- ineal circle, however, oc- cupies its proper place within these ambiguous bodies, alternate with the petals. We cannot doubt that the former are of the same nature as the scale of the stamens in Larrea, and the crown of the petals FIG. 37S- A petal of Silene Pennsylvania, with its crown or appendage. FIG. 379. A stamen of Larrea Mexicana, with a scale-like appendage cohering with its base on the inner side. FIG. 380. Diagram (cross-section) of the flower of Parnassia Oaroiiniana. 381. A petal, with the appendage that stands before it. CHORISIS OK DEDUPLICATION. 247 of Silene ; and we incline to consider the accessory body in such cases as homologous with the stipules of the leaf.* 459. It may also be noticed, that, while in collateral chorisis the. increased parts are usually all of the same nature, like so many similar leaflets of a compound leaf, in what is called transverse cho- risis there is seldom such a division into homogeneous parts ; but the original organ remains, as it were, intact, while it bears an append- age of some different appearance or function on its inner face, or at its base on that side. Thus the stamens of Larrea, &c. bear * For fuller illustrations of these theoretical points, the student is referred to the figures and text of The Genera of the United States Flora Illustrated, espe- cially to Vol. 2. — An able writer in Hooker's Journal of Botany and Kew Garden Miscellany, Vol. 1, p. 360, (with whom we are in accord as to the nature of col- lateral chorisis,) "being totally at a loss to find anything analogous in the ordinary stem-leaves " to this transverse or vertical multiplication of parts, in- clines to consider such appendages as those of the petals of Silene, Sapindus, Ranunculus, &c. as deformed glands, and the stamens thus situated, whether singly or in clusters, as developments of new parts in the axil of the petals, &c. It appears to us, however, that the leaves do furnish the proper analogue of such appendages as those of Fig. 378-381, and the similar petaloid scales of Sapindaceaj, Erythroxylea;, and the like, in the ligule of Grasses, and the stip- ules. The former occupies exactly the same position. The latter form an essential part of the leaf, and usually develop in a plane parallel with that of the blade, but between it and the axis ; particularly when they are of consider- able size, and serve as teguments of the bud, as, for example, in Magnolia (Fig. 156). The combined intrapctiolar stipules of Melianthus furnish a case in point, to be compared with the two-lobed internal scale of the stamens in Lar- rea, the two-cleft adnate appendage of the petals in Caryophyllea^ Sapindus, &c. ; and instances of cleft or appendaged stipules may readily be adduced to show that such bodies are as prone to multiplication by division as other foliar parts. The supposition of a true axillary origin of the organs in question, therefore, appears to be gratuitous, and it would certainly introduce needless complexity into the theory of the flower. Nor does it throw any light upon their morphology to call such appendages of petals " deformed glands " ; a term which is much too vague to have any assignable morphological value. In Linum true stipules are reduced to glands. At present, therefore, we think that the same general name may properly enough be employed both for the collateral and the vertical multiplication of organs, where two or more bodies occupy the place of one, carefully distinguishing, however, the two different cases. Some special term is needful for discriminating between such multiplication and that by the regular augmentation of floral organs through the development of addi- tional circles, and none the less so, because we recognize, in one or both kinds of chorisis, modes of division which are common to the floral organs and to the foliage. 248 THE FLOWER. 382 a scale-like appendage ; the petals of Sapindus, Cardiospermum, &c, a petaloid scale quite unlike the original petal ; the petals of Parnassia, a cluster of bodies resembling sterile filaments united below. 460. The Antepositioil or superposition of parts which normally alternate in the flower has in some cases been regarded as a case of transverse chorisis ; but it is susceptible of a simpler explanation. The principal case that occurs is that of the stamens, or the outer- most circle of stamens, being placed directly before the petals (in ordinary botanical lan- guage opposite the petals). The Vine (Fig. 384-386) and the Buckthorn families are good examples of this anomaly, as also is Clay- tonia in the Purslane fam- ily. And in Linden and many of its allies a cluster of stamens (Fig. 382, 383) stands be- fore each petal, the American Lindens 384 335 having also a petal-like scale in the centre of every cluster. The clusters must be viewed as multiplications of single stamens by collateral chorisis. The position of the stamens before the petals in these cases, as well as that of the numerous petals in certain double Camellias, arranged through- out in five vertical ranks, is most readily explained by supposing a re- turn to the regular f or five-ranked phyllotaxis of leaves (240). 461. In the genuine Geranium (Fig. 421) the position of the outer of the two sets of stamens before the petals evidently results from the abortion of an exterior circle (486) ; and perhaps this is the case in the Primrose family also. In the Barberry family there is an apparent anteposition of the sepals, petals, and stamens through- FIG. 382. Diagram of the flower of the American Linden, in a cross-section of the bud. 383. A cluster of stamens with the petal-like body in the middle. FIG. 3S4. Flower of the Grape, casting its petals before expansion. 385. The same, with- out the petals : both show the glands distinctly, within the stamens. 3S6. Diagram of the flower. COALESCENCE OF ITS PARTS. 249 out. But this arises from the symmetrical augmentation of each set of organs into two circles, which in the expanded flower appear like one. In the flower-bud of the Barberry the calyx is seen to consist of two alternating circles of sepals, three in each ; the corolla, of two circles of petals, three in each ; the three exterior petals alternating as they should with the inner circle of sepals, and the three interior ones alternating with these. But when the flower opens, the six petals, spreading apparently as one whorl, are necessarily opposed to the six sepals ; and the six stamens in two circles, which are still more confluent into one whorl, are equally opposed to these, taken six and six ; although they really alternate in circles of three. In other words, decussating verticils of threes necessarily form six vertical ranks (251, 441). It is just the same in the Lily, Crocus, and most Monocotyledonous plants ; where the perianth is composed of six similar leaves in two circles, and the andrcecium of six stamens in two circles, giving a regular alternation in threes ; although, when taken by the casual observer as composed of two circles of six, it gives the appearance of six stamens before as many petals. 462. The Coalescence or union of the parts of the same whorl or set of organs is so frequent, that few cases are to be found in which it does not occur, to a greater or less extent, in some portion of the flower. When the sepals are thus united into a cup or tube, the calyx is said to be monosepalous, or, more correctly, gamosepalous ; when the petals are united, the corolla is said to be monopetcdous, or gamopetalous. The latter is the appropriate term, as it denotes that the petals are combined ; but the former is in common use, al- though etymologically incorrect, as implying that the corolla consists of a single petal. The current names, in these cases, were given long before the structure was rightly understood. So, also, such a calyx or corolla is said to be entire, when the sepals or petals are united to their very summits ; or to be toothed, lobed, cleft, or parted, according to the degree in which the union is incomplete ; this lan- guage being employed just as in the case of the division of leaves (281). On the other hand, when the sepals are not united, the calyx is said to be polysepalous ; and when the petals are distinct, the corolla is said to be polypetalous ; that is, composed of several petals. 463. The union of the stamens with each other may occur either by their filaments, as in the Pea and most of the Pulse family, or by their anthers, as in the Sunflower and the whole Composite family, or 250 THE FLOWER. by both the filaments and the anthers, as in Lobelia and the Gourd. An account of the modes of such union, and of the terms employed to express them, may be found in Section VI. The union of the pistils is still more common than that of stamens, and is illustrated in Section VII. 464. The terms union, cohesion, and the like, must not be under- stood to imply that the organs in question were first formed as distinct parts, and subsequently cohei - ed. This is seldom the case. The union is congenital ; the members of a gamosepalous calyx, a gamopetalous corolla, &c. showed their union from the earliest period. The language we use has reference to our idea of these parts, as answering each to a single leaf. We might more cor- rectly say that the several leaves of the same circle have failed to isolate themselves as they grew. The same remark applies to the analogous case of 4G5. Adliatioil, or Consolidation, the union of different circles of floral organs with one another. This may take place in various de- grees. It presents the appearance of one circle or set of parts grow- ing out of another, as the corolla out of the calyx, the stamens out of the corolla, or all of them out of the pistil ; and therefore disguises the real origin of the floral organs from the receptacle or axis, in successive series, one within or above the other (421). The con- sideration of the flower as respects such consolidation, or its ab- sence, gives rise to three terms which are much used in descrip- tive botany, and which the student should thoroughly understand, viz. hypogynous, perigynous, and epigynous. 466. The first of these terms applies to the case in which there is no adnation or consolidation of unlike parts. That is, when the calyx, corolla, and stamens are borne (i. e. inserted) on the receptacle, they are said to be hypogynous (from two Greek words meaning under the pistil), as in Buttercup, Flax (Fig. 387), &c. The floral organs in such cases are also said to he free ; which is the term opposed to FIG. 387. Vertical section of a flower of the Common Flax, showing the normal or hypo- gynous insertion of parts. CONSOLIDATION OR ADNATION. 251 the adhesion of one organ to another, as that of distinct is to the cohesion of the parts of the same whorl or set of organs. Thus, the stamens are said to be distinct, when not united with each other, and to be free, when they contract no adhesion to the petals, sepals, or pistils ; and the same language is equally applied to all the floral organs. The word connate (born united) is applied either to the congenital union of homogeneous parts (as when we say that the two leaves of the upper pairs of the Honeysuckle are connate, Fi"-. 294, the sepals or stamens are connate into a tube, or the pistils into a compound pistil), or to the coalescence of heterogeneous parts (as that of the petals with the calyx, or of both with the pistil). But the word adnate belongs to the latter case only. 467. When such consolidation takes place, and the petals and stamens (which almost always accompany each other), or either of them, are inserted on the calyx, i. e. are adnate with the base of the calyx (as in the Cherry, Fig. 388, or Purslane, Fig. 389), they are said to be perigynous (liter- ally, placed around the pis- til). The real origin of the parts must be the same as in the former case, that is, the parts really belong to the re- ceptacle, in successive circles, one above or within the other, first the sepals, then the pet- als, within these the stamens, and within or above these the pistils ; but the true origin or position of some of the parts is here obscured by the adnation, at their base at least, of parts which are normally separate. In Fig. 388, the petals and stamens are adnate to the lower part of the calyx, but all are free from the pistil. But in Fig. 389, all four organs are consolidated below, as far as to the middle of the ovary. FIG. 3S3. Vertical section of a flower of the Cherry, to show the perigynous insertion of the petals and stamens. FIG 3S9. Similar section of the flower of the Purslane, showing an adnation of parts with the lower part of the overy. 252 THE FLOWER. 468. In the Apple, Hawthorn (Fig. 390), and many other plants, the consolidation extends farther, and the calyx is adnate to, i. e. . invests and coheres with the whole surface of the ovary, which accordingly appears to be under the rest of the flower, instead of the upper- most and innermost part, as it properly is. The earlier botanists called the flower, or calyx, in such cases, supe- rior, and the ovary and fruit inferior ; and when no such consolidation occurs, the flower, or calyx, &c. was said to be inferior, and the ovary superior. But these terms should be superseded by the equivalent and much more appropriate expressions of calyx adherent, in the one case, and calyx free, in the other ; or by that of ovary coherent with the calyx, and ovary free from the ccdyx, which is the same thing in other words.* More commonly the corolla and the stamens are adnate to the calyx beyond where these parts all separate from the pistil ; in which case they are still perigynous, or borne on the calyx. In some such cases, as in the Evening Primrose and Fuchsia, the tube of the calyx is prolonged far beyond the ovary, and the petals and stamens are inserted on it just below where it separates into its distinct lobes. 469. In other flowers the petals and the stamens are distinct at the line where the calyx separates from the top of the ovary, or are borne on the edge or face of a thickened disc (489) which crowns its summit, as in Aralia (Fig. 410), the Ivy, and all that family, in the whole Parsley family, the Cornel family, the Cranberry (Fig. 391), and the like. The stamens, &c, being then apparently borne on the ovary, are said to be epigynous (from two Greek words meaning " on the pistil "). * A favorite view at present is that the calyx in many eases (as in the Rose, Apple, &c.) actually begins at the place where it is distinct from the parts with- in, and that the so-called tube is the summit of the peduncle hollowed out, or developed around the pistils. This view can be correct in certain cases only, and the difference between it and the current view is really not so great as it seems. FIG. 390. Flower of Hawthorn vertically divided, to show the calyx adnate to the ovary. ITS IRREGULARITY. 253 470. In some few plants the stamens continue this adnation a little further, and cohere with the style, either with its base only, as in some species of Asarum, or with its whole length, as in Cypripedium fj (Fig. 468) and the whole Orchis | family. Then the flower is said \\ i\i| j \\ to be gynandrous ; — from two Greek words equivalent in mean- ing to stamens and pistil com- bined (519). 471. Irregularity. The flower is irregular when the parts of its different circles, or of one or 391 more of them, are not all alike in number, shape, or size. Irregularity may be the re- sult, therefore, either of the abortion or dis- appearance of some parts, or of their un- equal development or unequal union. The latter case may be first considered. 472. The Pea tribe affords a familiar illustration of irregular flowers arising from the unequal size and dissimilar form of the floral envelopes ; especially of the corolla, which, from a fancied resemblance to a butterfly in the flower of the Pea, Locust (Fig. 392), &c, has been called papilionaceous. The petals of such a corolla are dis- tinguished by separate names ; 6 the upper one, which is usually most conspicuous, being termed the vexillum, standard, or banner (Fig. 392', a) ; the two lateral 3 ^ ( (b) are called tvings {alee), and the two lower (c), which are usually somewhat united along their anterior edges, and together FIG. 391. Flower of Cranberry divided lengthwise, showing the petals and stamens epi- gynous. FIG. 392. Front view of a flower of the common Locust-tree (Hobinia Pseudacacia). FIG. 392'. Corolla of the same, the petals displayed. 22 254 THE FLOWER. form a body in shape resembling the keel, or rather the narrow prow, of an ancient vessel, are named the carina or heel. The calyx of the same blossom is slightly irregular by the unequal union of parts, the two upper sepals being united higher than the other three. In Baptisia these two sepals are coalescent to the tip, or nearly so, causing the calyx to ap- pear as if formed of four sepals instead of five In most Lupines, not only are the two upper sepals coa- lescent into one body near- ly or quite to the tip, but the three remaining ones are likewise united into one body, on the lower side of the flower, thus giving the calyx the appeai-ance of consisting of two petals in place of five. The ir- regularity of papilionaceous flowers likewise affects the stamens, which, although of symmetrical number, 396 viz. ten, or two circles, are in most cases unequally coalescent, nine of them being united by the cohesion of their filaments for the greater part of their length, while the tenth (the posterior) stamen is distinct ; as is illustrated in the sec- tion on the stamens (518). But in Amorpha (Fig. 395), which belongs to the same tribe of plants, the ten stamens are united barely at their base ; and there is a complete return to regularity in those of Baptisia (Fig. 394) and Sophora, which are perfectly distinct or separate. The Violet (Fig. 397) offers another very familiar form of irregu- lar flowers ; the irregularity belonging FIG. 393. Papilionaceous flower of Baptisia. 394. The same, with the petals removed, showing the ten distinct stamens. FIG. 395. Flower of Amorpha. 395'. The same, with the solitary petal removed, showing the slightly monadelphous stamens. FIG. 396. Flower of Viola sagittata. 397. Its sepals and petals displayed. SUPPRESSION OR ABORTION OF TARTS. 255 mainly to the corolla, the lower petal of which is prolonged back- ward into a sac or spur. The Larkspur and Monkshood (Fig. 398- 402) are irregular both in the calyx and the corolla, not only by a diversity in the size and shape of homologous parts, but also by the suppression of some of them. "We may therefore consider them under the next head. •473. Of irregular monopetalous flowers the most common form is the bilabiate or two-lipped, as in the corolla of the Sage, Snap- dragon, and most of the large families to which they belong (Fig. 4G0) : this, like the calyx of the Lupine, described above, arises from the unequal union of the parts. The same is the case with the two-lipped corolla of the "Woodbine and other Honeysuckles, only here, instead of two lobes or petals forming the upper lip and three the lower, four petals enter into the composition of the upper lip, leaving only one for the lower (Fig. 861). The Trumpet Honeysuckle returns nearly to regularity again, the whole five petals being coalescent into a tube to near the top, leaving an al- most equally five-lobed border. The corollas of Germander (Fig. 99 G) and of Lobelia (Fig. 902) are further irregular by a want of union on the upper side of the blossom : and the ligulate or open and strap-shaped corolla of Coreopsis (Fig. 325, c) and other Com- posite evidently answers to such a regular monopetalous corolla as a, split down on one side and outspread. 474. Suppression or Abortion, that is, the complete or the partial obliteration of some member, is a common cause of irregularity. The term suppressio?i is used when parts which belong to the plan of the blossom do not actually appear in it. The term abortion is applied not only to such disappearance, but to partial obliteration, as where a stamen is reduced to a naked filament, or to a mere rudi- ment or vestige, answering to a stamen and occupying the place of one, but incapable of performing its office. Such obliteration, whether partial or complete, may affect either a whole circle of organs or merely some of its members. The former interferes with the completeness of a flower, and may obscure the normal order of its parts. The latter directly interferes with the symmetry of the blossom, and may be first considered. 475. Suppression of some Parts of a Circle of Organs. The Larkspur and Aconite or Monkshood furnish good examples of flowers which are both irregular and symmetrical. The calyx of the Larkspur (Fig. 398, 399) is irregular by reason of the dissimilarity of the five 256 THE FLOWER. sepals, one of which, the uppermost and largest, is prolonged poste- riorly into a long and hollow spur. Within these, and alternate with them as far as they go, are the petals, only four in number, and these of two shapes, the two upper ones having long spurs which are re- FIG. 398. Flower of a Larkspur. 399. The five sepals (outer circle) and the four petals (inner circle) displayed. 400. Ground-plan of the calyx and corolla. FIG. 401. Flower of an Aconite or Monkshood 402. The five sepals and the two small and curiously-shaped petals displayed : also the stamens and pistils in the centre. 403. Ground-plan of the calyx and corolla ; the dotted lines, as in Fig. 400, representing the sup- pressed parts. SUPPRESSION OR ABORTION OF PARTS. 257 ceivecl into the spur of the upper sepal ; the two lateral ones having a small but broad blade raised on a stalk-like claw ; and the place which the fifth and lower petal should occupy (marked in the ground plan, Fig. 400, by a short clotted line) is vacant, this petal being sup- pressed, thereby rendering the blossom unsymmetrical. In Aconite, (Fig. 401, 402) the plan of the blossom is the same, but the upper- most and largest of the five dissimilar sepals forms a helmet-shaped or hood-like body ; and as to the petals, three are wanting altogether (their places are shown by the dotted lines in the ground plan, Fig. 403) ; the two upper ones, which extend under the hood, only re- main, and these are so reduced in size and so anomalous in shape that they would not ordinarily be recognized as petals. One of them enlarged is exhibited in Fig. 404. Petals, &c. of this and other extraordinary forms were termed by Linnaeus Nectaries, an unmeaning or mislead- ing name, as they are no more likely to secrete honey than ordinary petals are. 405 476. The papilionaceous corolla (472) becomes strikingly unsymmetrical by suppression in Amorpha (Fig. 395). Here the corolla is uniformly reduced to a solitary petal (the standard), the other four petals being totally obliterated. This obliteration is foreshadowed in Ery- thrina herbacea of the Southern States, and other species, in which all the petals except the standard are small and inconspicuous. While the blossom of the common Iiorsechestnut, although irregular, is symmetrical, so far as respects the calyx and corolla, that of our nearly related Buckeyes gener- ally wants one of the five petals, a vacant place on the anterior side of the flower indicating its absence. 477. The suppression or abortion of eome of the stamens requisite to the symmetry of the blossom is According to the ordinary view, the six stamens of the flowers of the Mustard family (Fig. 405, 406), where the sepals and petals are in fours, is explained by supposing that, out of two circles of stamens, four in each, two stamens of the outer circle are very common. FIG. 404. One of the petals of an Aconite or Monkshood, enlarged. FIG. 405. Flower of Mustard 406. Its six stamens and the pistil, enlarged. 22* 258 THE FLOWER. suppressed. But we incline to the opinion that this sort of flower is rendered unsymmetrical, not by the suppression of two short sta- mens, but by the chorisis or division of the two stamens each into a pair (456, Fig. 368). 478. Most flowers which are irregular by the unequal union of 407 the petals, especially those with a bi- labiate corolla (473, 511), are likewise unsymmetrical by the abortion of one or more of the stamens. In the Cat- nip, Balm, &c, and in the Snapdragon, Monkey-flower, Foxglove, and the like, as also in Gerardia (Fig. 407), where the corolla is only slightly ir- regular, four stamens occupy their proper places alternate with its lobes, but the fifth stamen is altogether want- ing. In its place, however, the corolla of the Figwort, belonging to the same family as the Snapdragon and Ge- rardia, bears a small scale, and that of Chelone and Pentstemon (Fig. 408) bears an antherless filament, which, from its position, must be the wanting stamen, in an abortive state ; and in one species it has actually been found with a perfect or an imperfect anther, completing the symmetry of the flow- er. The four perfect stamens in these cases are of unequal length, two of them being longer than the other two (i. e. they are didynamous, 520). The two shorter stamens also disappear in many such plants, as in Gratiola or Hedge-Hyssop, — sometimes leaving vestiges in their place, and sometimes not ; also in Sage, Horse-Mint, and the like. Here three stamens out of five are suppressed. So they commonly FIG. 407. Corolla of Gerardia purpurea laid open, with the four stamens the place which the fifth should occupy indicated by a cross. FIG. 408. Corolla of Pentstemon grandiflorus laid open, with its four stamens, and a sterile filament in the place of the fifth stamen. FIG. 409. Corolla of Catalpa laid open, with two perfect stamens and the vestiges of three abortive ones. SUPPRESSION OR ABORTION OF PARTS. 259 are in the blossom of Catalpa (Fig. 409), but their vestiges remain in the form of small sterile filaments, two o£, /which, however, occa- sionally bear anthers, either perfect or rudiniefrtary. 479. The suppression of a portion of the pistils required to com- plete the symmetry of the flower is exceedingly common. The tendency to obliteration seems to increase as we advance towards the centre of the blossom, owing, doubtless, to the greater pressure exerted on the central parts of the bud, and the progressively di- minished space the organs have to occupy on the conical receptacle. Thus, while the corolla, when present at all, almost always consists of as many leaves as the calyx, the members of the stamineal circle or circles are frequently fewer in number, and the pistils are still more commonly fewer, excepting where the axis is prolonged for the reception of numerous spiral cycles. Thus, the pistils, which present the symmetrical number in Sedum, and all plants of that family (Fig. 334, 335, 355, 3G1), are reduced to two, or rarely three, in the allied Saxifrage family, while the other floral circles are in fives. So, in the Wild Sarsaparilla (Fig. 410) and Spikenard, the flowers are pentamerous throughout, although the ovaries of the five pistils are united into one ; but they are reduced to three in the Ground-nut, and to two in the Ginseng, belonging to the same genus, as also in all Umbelliferous plants. Although the pistils are in- definitely augmented in the Rose, Strawberry, and the greater part of Rosaceous plants, or are of the normal number five in Spiraea, yet there are only two in Agrimonia, one or rarely two in Sangui- sorba, and uniformly one in the Plum and Cherry (Fig. 388), although the flowers of the whole order are formed on the pentame- rous, or sometimes the tetramerous plan, and with a strong tendency to augmentation of all the organs. And the Pulse family has, almost without exception, five members in its floral envelopes, and ten, or two circles, in its stamens, but only a single pistil (Fig. 358). 480. Suppression of one or more whole Circles. A complete flower, as already remarked (41 G), comprises four whorls or sets of organs; namely, calyx, corolla, stamens, and pistils. When any of these four circles or kinds of organs are wanting, the flower is said to be in- complete. The non-production of any one or more of the whorls is not uncommon. The calyx, however, is seldom if ever wanting when the corolla is present, or rather, when the floral envelopes con- sist of only one whorl of leaves, they are called calyx, whatever be their appearance, texture, or color, unless it can somehow be shown 260 THE FLOWER. that an outer circle is suppressed.* For since the calyx is fre- quently delicate and petal-like (in botanical language petahid or colored), and the corolla sometimes greenish or leaf-like, the only real difference between the two is, that the calyx represents the outer, and the corolla the inner series ; and even this distinction becomes more or less arbitrary when either, or both, of these or- gans consist of more than one circle. The apparent obliteration of the calyx in some cases is owing to the entire cohesion of the tube with the ovary, and the reduction of the free portion, or limb, to an obscure ring or border, either slightly toothed or entire, as in Aralia (Fig. 410), Fedia (Fig. 882), Cornus, the fertile flowers of Nyssa, &c. In Composite, the partially obliterated limb of the calyx, when present at all, consists of scales, teeth, bristles, or a ring of slender hairs (as in the Thistle), and receives the name of pappus. 481. The petals, however, are frequently absent; when the flower is said to be apetalous, as in the Anemone (Fig. 411), Clematis, Caltha, &c, in the Crowfoot family, other genera of which are furnished with both calyx and corolla ; and as in some species of Buckthorn, while others have manifest although small petals. They are constantly wanting in a large number of families of Ex- ogenous plants, which on this account form the division Apetalcs. When the calyx is present while the corolla is wanting, the flower is said to be monochlamydeous, that is, with a perianth (417) or floral envelope of only one kind ; as in the cases above mentioned. * In our Northern Zanthoxylum the monochlamydeous perianth which is present may, however, be justly held to be the corolla, and not the calyx, be- cause the five stamens alternate with it, just as they do with the undoubted petals of Z. Carolinianum : in this case, therefore, we may say that the calyx, and not the corolla, is suppressed. See Genera Illustrate!, Vol. 2, p. 148, tab. 156. FIG. 410. Flower of Aralia nudicaulis, vertically divided ; the limb of the calyx obsolete. FIG. 411. Flower of Anemone Pennsylvania ; apetalous, the calyx petaloid. SUPPRESSION OR ABORTION OF PARTS. 261 482. In some flowers, moreover, as in the Lizard's-tail (Fig. 412), both the calyx and the corolla are entirely wanting, and the blossom is achlamydeous, i. e. destitute of any perianth or floral envelopes whatever. Having the es- sential organs, viz. the stamens and pistils, how- ever, this flower also is perfect {hermaphrodite, or bisexual), although incomplete. 483. The abortion of all the stamens or all the pis- tils of a flower is common enough, as well in flowers that have as in those that have not complete floral envelopes ; but whenever either of these essential organs are abortive or wanting in some blossoms, they are present in others of the same species, either on the same or on different individuals. Flowers of this kind having stamens only or pistils only are said to be separated, diclinous, or unisexual. And the flower which has the stamens but no pistils, or only imperfect ones, is said to be staminate, sterile, or male ; while that provided with pistils, but with no stamens, or only im- perfect ones, is pis- tillate, fertile, or fe- male. Not to multi- ply examples, in Smi- lax and in Menisper- mum (Fig. 413, 414) we have good instan- ces of separated flow- ers in which the abor- tion is confined to the stamens or the pistils, the floral envelopes being present and 418 417 FIG. 412. Flower of Lizard's-tail (Saururus ceriums), magnified. FIG. 413. A staminate flower of Menispermum or Moonseed. 414. A pistillate flower of the same. The latter has six abortive stamens : the former, mere vestiges of pistils. FIG 415. A catkin of staminate flowers of Salix alba. 416. A single staminate flower de- tached and enlarged (the bract turned from the eye). 417. A pistillate catkin of the same species. 41S A detached pistillate flower, magnified. 262 THE FLOWER. complete. And in the "Willow (Fig. 415-418) we have separated flowers extremely simplified by abortion. The flowers are crowded in catkins, each one in the axil of a bract : the staminate flowers consist of a few stamens merely, in this species of only two (Fig- 41 G), and the pistillate, of a pistil merely (Fig. 418). That is, the flowers are wholly destitute of calyx and corolla (unless a little glandular scale on the upper side should be a rudimentary perianth of a single piece), and in one set of blossoms the stamens are also suppressed ; in another, the pistils. The stamens vary in number in different species, from two to five. If there were only one of the latter, an instance would be afforded of flowers reduced, not merely to one kind of organ, but to a single member. Now there is one species of Willow, which ap- pears to have its sterile blossoms reduced to a solitary stamen. It has therefore been named Salix monandra. But on in- spection this seemingly single stamen is found to consist of two united with each other quite to the top (Fig. 419). Here, as in many other cases, the normal condi- tion of the flower is not only much altered by the sup- pression of most of the organs, but disguised by the coa- lescence of those that remain. 484. In separated flowers the two kinds of blossoms may be borne either upon different parts of the same individual, or upon entirely different individuals. The flowers are said to be monoecious when both kinds are borne on the same plant ^ as in Indian Corn, the Birch, the Oak, Beech, Hazel, Hickory, &c. if and they are called dioecious when borne by different individuals ; as in the Willow and Poplar, the Sassafras, the Prickly Ash, the Hemp and Hop, Moonseed (Fig. 413, 414), &c. Occasionally, while some of the flowers are staminate only, and others pistillate only, a por- tion are perfect, the different kinds occurring either on the same or different individuals ; as in most Palms, in many species of Maple, &c. : plants with such flowers are said to be polygamous. 485. In some of the blossoms of certain plants both stamens and pistils are wanting. This is the case with those that occupy the margin of the cymes of the Hobblebush and some-other Viburnums, and of Hydrangea (Fig. 420), or even with the whole cluster in cultivated monstrous states, as in the Snowball or Guelder-Rose of the gardens (Viburnum Opulus). Here the enlarged corollas FIG. 419. A staminate flower of Salix purpurea (or monandra), with the stamens coalescent (monadelphous anil syngenesious), so as to appear like a single one. SUPPRESSION OR ABORTION OF PARTS. 263 make the whole blossom. Such flowers, being neither staminate nor pistillate, are said to be neutral. In so-called compound flowers (394) the strap-shaped marginal flowers are sometimes neutral, as in Coreopsis (Fig. 324, 325), Mayweed, and Sunflower. In some Grasses and other plants such neutral flowers want the floral en- velopes also, or are reduced to an abortive rudiment. 486. The suppression or abortion of a whole circle of organs in a symmetrical flower does not destroy its symmetry, if we take note of the absent members. Thus a monochlamydeous flower, with a single full circle of stamens, usually has the latter placed opposite the leaves of the perianth, that is, of the calyx, the corolla or in- tervening circle having failed to appear. But when, with the abor- tion of the primary circle, say of the stamens, we have an augmenta- tion of one or more additional circles of the same kind of organ, the law of alternation appears to be violated; the stamens that are present, or the outer circle of them, standing before the petals, in- stead of alternate with them. It is customary to assume this ex- planation for all cases of the anteposition of the stamens to the pet- als, whether in the Primrose family, in Claytonia, in the Vine (Fig. FIG. 420. Cyme of Hydrangea arborescens, with the large marginal flowers neutral 2G4 THE FLOWER. 384), or the Buckthorn, &c. But more probable explanations for some such cases have already been given (459, 4G0). It can no longer be deemed sufficient to assume the obliteration of a normal floral circle, and the production of a second one, when no traces of the former can be detected and no clear analogy shown with some strictly parallel instance. Yet we may confidently apply this view when we do find traces of obliterated organs, as in the Geranium family, for example. The pentamerous flower of Geranium exhibits ten stamens, plainly occupying two rows, the five of the exterior circle shorter than the others. One set of these stamens alternates with the petals, the other is opposed to them. But on close exami- nation, we perceive that it is the inner circle of stamens that alter- nates with the petals ; those of the outer circle stand directly before them. This is a not uncommon case where there are just twice as many stamens as there are petals or sepals. In this instance the explanation of the anomaly is furnished by the five little bodies, called by the vague and convenient name of glands, which stand on the receptacle between the petals and the sta- mens, and regularly alternate with the former. They accordingly occupy the exact position of the original stamineal circle : wherefore, as 421 situation is the best indication of the nature of organs, we may regard them as the abortive rudiments of the five proper stamens, here obliterated. In the annexed diagram (Fig. 421) these are accordingly laid down in the third circle, as five small oval spots, slightly shaded. The actual stamens consequently belong to two augmented circles, those of the exterior and shorter set of which (represented by the larger, unshaded figures), normally alternating with the glands, are of course opposed to the petals, and those of the inner and larger set, normally alternating with the preceding, neces- sarily alternate with the petals. This view is further elucidated by the closely allied genus Erodium, where all the parts are just the same, except that the five exterior actual stamens are shorter still, and are destitute of anthers ; that is, the disposition to suppression, which has caused the obliteration of the primary circle of stamens and somewhat reduced the second in Geranium, has in Erodium FIG. 421. Diagram (cross-section ) of the flower of Geranium marulatum, exhibiting the relative position of parts, especially the glands alternate with the petals, and the two rows of stamens within them. SUPPRESSION OR ABORTION OF PARTS. 2G5 rendered the latter abortive also, leaving those of the third row alone to fulfil their proper office. And in a South African genus, Monso- nia, five stamens actually occur in the place of these glands, making fifteen real stamens, or three circles. The general plan of the flower is the same in the Flax family, except that the glands which answer to the outer rank of stamens are still less conspicuous, and those of the next circle are reduced to small abortive filaments, or to minute teeth in the ring formed by the union of all the filaments into a cup at the base, leav- ing five perfect stamens, which, though they alternate with the petals indeed, belong to a third circle (Fig. 422, 423). In a few species of Flax, this second circle of stamens is perfectly obliterated, so that no vestige is to be seen. 487. The complete suppression of two or three of the circles be- longing to the complete flower, and of a part of the members of what remains, reduces a blossom to the last degree of simplicity. Among the simplest of perfect flowers are those of Callitriche (Fig. 1136- 1138), which have neither calyx nor corolla; and only one stamen, as is expressed in the annexed diagram (Fig. 424) ; yet the four- lobed pistil shows that the blossom was constructed on the o o plan of four. And 424 "1 Zs X ^ S X even this stamen is suppressed in cer- tain blossoms, and the pistil in others. In Euphorbia (also to be illustrated under the family to which it belongs, Fig. 1143) the flowers are always separated, and the staminate blossom is reduced to a single stamen, the pistillate to a single three-lobed pistil (Fig.425). And in the Willow, as already noticed (438), the pair of stamens which represents one sort of blossom, and the single pistil which repre- sents the other, are widely separated, being borne on distinct trees. FIG. 422. Flower of Linuni perenne. 423. Its stamens and pistils enlarged. FIG. 424. Diagram of a perfect flower of Callitriche, with no floral envelopes, one stamen, and a four-celled pistil. FIG. 425. Diagram of the moncecious flowers of Euphorbia : o, the pistillate flower re- duced to a mere three-celled pistil ; and b, one of the staminate flowers reduced to a single stamen. FIG. 426. Diagram of the dioecious flowers of the Willow : a, one of the pistillate flowers reduced to a solitary pistil ; 6, a staminate flower reduced to a pair of stamens. 23 as & . o 266 THE FLOWER. 4S8. Unusual States of the Receptacle. The receptacle (421) is commonly small, short, and inconspicuous, being merely the extrem- ity of the flower-stalk upon which the sev- eral organs are inserted (Fig. 343). Some- times, however, it is remarkably enlarged or elongated. A striking instance of an en- larged receptacle is found in Nelumbium, where it is dilated into a large top-shaped body, nearly enclosing the pistils in sep- arate cavities (Fig. 427). Whenever the pistils of a flower are very numerous, the receptacle is more or less enlarged for their insertion, as in Magnolia, the Raspberry and Blackberry, &c. In the Strawberry the enlarged and conical receptacle (Fig. 428), bearing the pistils on its surface, becomes the edible portion in fruit. In the Rose (Fig. 429) the receptacle is deeply concave, instead of convex, being urn- shaped, invested by the adnate tube of the calyx, and bearing the petals and stamens on its bor- der and the numerous pistils on its whole hol- low surface (Fig. 429). It is much the same in Calycanthus (Fig. 814- 819). In Geranium, and 423 many allied plants, the receptacle is prolonged between the ovaries, and coheres with their styles (Fig. 430) ; these, however, separating at maturity (Fig. 431). In Umbelliferous plants a similar but more slender prolongation of the receptacle is extended upwards between the contiguous faces of the two united ovaries which form the fruit FIG. 427. The enlarged, top-shaped receptacle of Nelumbium, bearing the pistils, im- mersed in hollows of its upper face. FIG. 428. Longitudinal section of a young strawberry, enlarged. FIG. 429. Similar section of a young Rose-hip. FIG. 430. Gynaecium of Geranium maculatum, or Cranesbill, enlarged. FIG. 431. The same at maturity, with the fire pistils splitting away from the long beak or receptacle and hanging from its top by their styles. THE RECEPTACLE, DISK, ETC. 267 in that family. Occasionally one or more of the internodes between successive floral circles elongate ; as between the calyx and the corolla in Pinks, and especially in Silene, forming a stalk within the calyx, on which the rest of the flower is raised (Fig. 432) ; while in many Gentians the inter- node above the circle of stamens is developed, rais- ing the pod on a stalk of its own. This is a common case in the Caper family ; in which the genus Gynan- dropsis (Fig. 433) exhibits a remarkable development of the whole receptacle. It is enlarged into a flattened disk, where it bears the pet- als, and is then prolonged 4S2 into a conspicuous stalk which bears the stamens, — or rather, to which the bases of the stamens are adnate, — and then into a shorter and more slender stalk for the pistil ; thus separating the four circles or sets of organs, like so many whorls of verticillate leaves. The general name for this kind of stalk, as contradistinguished from the pedicel or stalk of the flower, is the Stipe ; and whatever organ or set of organs is thus elevated is said to be stipitate. Whenever it is necessary to particularize the portion of the receptacle thus devel- oped, the stipe is termed the Anthophore when it appears just above the calyx, and elevates the petals, stamens, and pis- tils ; the Gonophore, when it supports both the sta- mens and pistils ; and the Gynophore, Gynobase, or Carpophore, when it bears the gynajcium alone. The stalk which sometimes supports each simple pistil of the gynrecium (as in Coptis or the Goldthread) is called a Thecaphore. This, however, does not belong to the receptacle at all, but to the pistil itself, and is ho- mologous with the leafstalk. «4 489. A Disk is a part of the receptacle, or a growth from it, en- larged under or around the pistil. Like the other parts of the flower, FIG. 432. Section of a flower of Silene Pennsylvania, showing the stipe or anthophore. FIG. 433. Flower of Gynandropsis, with a remarkably elongated receptacle. FIG. 434. Disk of the Orange, underneath the pistil (hypogynous). 2GS THE KLOWElt. it is hypogynous (4GG), when free from all union either with the pis- til or the calyx, as in the Rue and the Orange (Fig. 434). It is perigynous (4G7), when it adheres to the hase of the calyx, as in the Buckthorn (Fig. 435, 436) ; and where the calyx is adnate to the ovary, as in the Apple, Hawthorn (Fig. 390), &c., there is commonly a disk in- terposed between the two. The disk is sometimes expanded on the summit of such an ovary, when it is said to he epigynous (469), as in Cornus, and all Umbelliferous plants. Sect. V. The Floral Envelopes in Particular. 490. Their Development, or Organogeny, first requires a brief notice. The flower-bud is formed in the same way as the leaf-bud ; and what has been stated as to the fonnation of the leaves of the branch (273) equally applies to the leaves of the flower. The sepals are necessarily the earliest to appear, which they do in the form of so many cellular protuberances, at first distinct, inasmuch as then their tips only are eliminated from the axis. Each one may complete its development separately, like an ordinary leaf, when the sepals re- main distinct. Or the lower and later-eliminated portions of the forming organs of the circle coalesce as they grow into a ring, which, further developed in union, forms the cup or tube of the gamophyl- lous calyx. In some cases, it would appear that the sepals may at first grow separately, and afterwards, though only at a very early period, coalesce by the cohesion of their contiguous parts. The sev- eral parts of an irregular calyx are at first equal and similar ; the irregularity appears in their subsequent unequal growth. The pet- als or parts of the corolla originate in the same way, a little later than the sepals. Their coalescence in the gamopetalous corolla is congenital ; the ring which forms its tube appearing nearly as early as do the slight projections which become its lobes and answer to the summits of the component petals. The rudiments of the petals are visible earlier than those of the stamens : but their growth is at first FIG. 435. Flower of a Buckthorn, showing a large perigynous disk. 436. Vertical section of the same. AESTIVATION OR PIMiFLOKATION. 269 retarded, so that the stamens are earlier completed, and their anthers surpass them, or often finish their growth, while the petals are still minute scales : at length they make a rapid growth, and enclose the organs that belong above or within them. Unlike the sepals in this respect, the base of the petal is frequently narrowed into a portion which corresponds, more or less evidently, to the petiole (the claw), and which, like the petiole, does not appear until some time after the blade or expanded part ; the summit being al- ways the earliest and the base the latest portion formed. As the envelopes of the flower grow and expand, those of each circle adapt themselves to each other in various ways, and acquire the relative positions which they occupy in the flower-bud. Their arrangement in this state is termed 491. Their Estivation or Prrcfloration. The latter would be the preferable term ; but the former is in common use ; the word Esti- vation (literally the summer state) having been devised for the purpose by Linnreus ; — for no obvious reason except that he had already applied the name of Vernation (the spring state) to express the analogous manner in which leaves are disposed in the leaf-bud. The same terms are employed, and in nearly the same way, in the two cases, but with some peculiarities. As to the disposition of each leaf taken by itself, the corresponding terms of vernation (257) wholly apply to aestivation. The arrangement in the bud of the several members of the same floral circle in respect to each other, is of much importance in systematic botany, on account of the nearly constant characters that it furnishes, and also in structural botany, from the aid it often affords in determining the true relative super- position or succession of parts on the axis of the flower, by observ- ing the order in which they overlie or envelope each other. 492. The various forms of aestivation that have been distinguished by botanists may be reduced to three essential kinds, namely, the imbricative, the contorted or convolutive, and the valvular.* 493. Imbricative aestivation, in a general sense, comprises all the modes of disposition in which some members of a floral circle are exterior to the others, and therefore overlie or enclose them in * "We should properly say of the (estivation that it is imbricative, eonvolutive, valvular, &c, and of the calyx and corolla, or of the sepals, &c, that they arc imbricate or imbricated, convolute, valvate, &c. in aestivation ; but such precision of language is seldom attended to. 270 THE FLOWER. the bud. This must almost necessarily occur wherever the parts are inserted at distinguishable different heights, and is the natural result of a spiral arrangement. The name^fc most significant when successive leaves are only partially covered by the preceding, as in Fig. 207. Here they manifestly break joints, or are disposed like tiles or shingles on a roof, as the term imbricated denotes. It is therefore equivalent to the spiral arrangement : and, on the other hand, we properly apply the term imbricated to any continuous succession of such partly overlying members ; as when we say of appressed and crowded leaves that they are imbricated on the stem, or thus express the whole arrangement of the scales of a bud (Fig. 153), or a bulb (Fig. 172), or of a catkin or cone (Fig. 209). The alternation of the petals with the sepals, &c. necessarily renders the floral envelopes likewise imbricated in the bud, taken as a whole. But in proper aestivation, what we have to designate is the arrangement of the parts of the same floral circle (say the five sepals or the five petals) in respect to each other. 494. Now when the sepals or -^===5;^ ^ ?s===:t v * ne P e * a ^ s are three in number, /^ "\\ /v^^ ==== X\\ anc ^ are re g u l ai 'ty imbricated in " " Ul m\ lhc bud ' as in Fi °' 437 ' tlie tliree leaves are arranged just as in three-ranked phyllotaxis (238, «7 438 Fig. 203) ; that is, with the first petal exterior to the others, the second is covered by the first on one side while it covers the third on the other. When they are five (as in the calyx of Geranium, Fig. 439), they are disposed just as in five-ranked or quincuncial phyllotaxis with the axis shortened (240, Fig. 20G) ; viz. two leaves are exterior, two wholly interior, and one (the third) with one edge covered by No. 1 on one side while it covers No. 5 with its other edge. So that this, the regular mode of imbrication when the parts are in fives, is termed quincuncial aes- tivation, or the parts are said to be quincuncially FIG. 437. Diagram of a three-leaved (trimerous) calyx and corolla, both imbricated in aestivation. FIG 438. Diagram of the estivation of three petals (or one circle of the petals) of Magno- lia, similarly imbricated, but strongly enwrapping, each making nearly a circle. FIG. 439. Diagram of the imbricative aestivation of the calyx and the convolutive aestiva- tion of the corolla of Geranium ; the sepals numbered. ^estivation or pr^efloration. m 271 imbricated. We have here the advantage of being able to number the successive sepals, or petals, since the third leaf is not only recog- nizable by its iutajdWiaR position, but also indicates the direction in which the spfl BEJS- 20G and Fig. 439). 495. It must ber^WI Weed, in the comparison, that the parts of successive cycles are superposed in the foliage, while those of the floral circles alternate. Regular imbrication in the 4-merous flower gives two outer and two inner members in aestivation (as in the calyx of Cruciferous blossom-;, Fig. 3G7), on the principle of two decussating pairs of leaves (441) ; or it may sometimes be refer- able to a modification of some alternate spiral arrangement. 496. The degree of overlapping depends upon the breadth of the parts and the state of the bud ; it naturally grows less and less as the bud expands and is ready to open. It is from the full-grown flower-bud, just before anthesis (or the .opening of the blossom), that our diagrams are usually taken ; in which the parts are represented as moderately or slightly overlapping. The same overlapping car- ried to a greater extent will cause the outer leaf to envelope all the rest, and each succeeding one to envelop those within ; as shown in Fig. 438 from one circle of petals of a Magnolia taken in an early state of the bud. To this, however, has not improperly been applied the name of convolute, from its similarity to the convolute vernation of the leaves of the branch (257), similarly rolled up one within the other. But it is practically inconvenient, and wrong in principle, to designate different degrees of the very same mode by distinct names ; furthermore, it is to the next general mode of aestivation that the name of convolute is more commonly applied, at least in recent sys- tematic botanical writings. 497. There are numerous cases of imbricative aestivation, espe- cially in irregular flowers, where the overlapping of parts does not altogether accord with what must needs be their order of succes- sion on the axis. In the 5-merous calyx and corolla of all truly papilionaceous flowers, for example, one edge of the sepal or the petal No. 2 is placed under, instead of over, the adjacent edge of No. 4, in consequence of which three, instead of only one, of the leaves have one edge covered and the other external ; as is shown in Fig. 358. Since, in the corolla of this kind of blossom, the ex- terior petal, here the vexillum (472), is the larger, and at first em- braces all the rest, this modification of imbricative aestivation has received the name of vexillary. As nearly the same thing occurs 272 THE FLOWER. ^^ in the Violet, it is probably caused by some slight dislocation that takes place during the early growth of organs in the irregular blos- som. It is not restricted to irregular flowers, however, but occurs as a casual variation, or perhaps more frequent- ly than the quincuncial, in the regular corolla of the Linden (as is shown in Fig. 440). A slight obliquity in the position of the petal No. 2, assumed at an early period, would account for the whole anomaly. That this suggests the true explanation is almost demonstrated by 440 the varying aestivation of the corolla of the Linden ; in which the same bunch of blossoms often furnishes in- stances of regular quincuncial imbrication, of the modification here referred to, and of a similar disposition of the fifth petal, throwing one of its edges outwards also. If the first petal were also to par- take of this slight obliquity, the imbricative would be completely converted into what is variously named 498. The contorted, twisted, or convolutive aestivation (Fig. 439, 441, the corolla, and 442). In this mode, the leaves of the circle are all, at least apparently, inserted at the same height, and all occupy the same relative position : one edge of each, being directed ob- liquely inwards, is covered by the adjacent leaf on that side, while the other covers the corresponding margin of the contiguous leaf on the other side. This is owing to a torsion or twisting of each member on its axis early in its development ; so that the leaves of the floral verticil, instead of forming arcs of a circle, or sides of a polygon having for its centre that of the blossom, severally assume an oblique direction, by which one edge is carried partly inward and the other outward. This contorted aestivation is rare in the calyx, but com- FIG. 440. Diagram of the plan and restivation of the flower of the Linden. FIG. 441. Diagram of the imbricated calyx of Wallflower (two outer and two inner sepals), and within the strongly contorted or convolute corolla. 442. Corolla of the latter more open. 443. Cross-section of the plaited tube of the corolla of Campanula. 444. Similar section of the plaited and supervolute corolla of CoutoIvuIus. AESTIVATION OB PR;EFLORATION. 273 mon enough in the corolla. When this obliquity of position is stromr, the petals themselves are usually oblique, or unequal-sided, from the lesser growth of the overlapped side. This is well seen in the pet- als of most Malvaceous plants, and in those of the St. Johnswort. In the Pink, however, and in many other instances, the petals are symmetrica], although strongly convolute in aestivation. When the petals are broad, this convolute arrangement is frequently conspicu- ous in the fully expanded flower, as well as in the bud. The con- volution in the bud is often so great, that the petals appear as if strongly twisted or rolled up together, each being almost completely overlapped by the preceding, so that they become convolute nearly in the sense in which the term is used in vernation ; as in the Wall- flower (Fig. 441, 442). Although there is some diversity of usage, the terms convolute and contorted in aestivation are now for the most part employed interchangeably, or nearly so. 499. The valvular or valvate aestivation is that in which the parts of a floral circle are placed in contact, edge to edge, throughout their whole length, without any overlapping, as in the calyx of the Mal- low and Linden, Fig. 440. Here the members of the circle stand in an exact circle, no one being in the least degree lower or exterior. The edges of the sepals or petals in tins case are generally abrupt, or as thick as the rest of the organ ; by which mark the valvate aes- tivation may commonly be recognized in the expanded flower. 500. By inflexion of the edges, the valvate aestivation passes by gradations into the induplicate (Fig. 445), and this, when the margins are in- /^fjL f^pl rolled, into the involute (Fig. 446), as is (( ^^ (o) ^ exemplified by the calyx of different spe- cies of Clematis. On the other hand, the valvate calyx of many Malvaceous plants has the margins projecting outwards into salient ridges, or is redupli- cate, in aestivation. 501. In the Mignonette, and some other flowers, the aestivation is open ; that is, the calyx and corolla are not closed at all over the other parts of the flower in the bud. 502. The form of the tube of the calyx or corolla in the bud sometimes has to be considered. Sometimes it is plicate, or plaited 'lengthwise ; and the plaits may be turned either inwards, as in the FIG. 445. Diagram of the valvate-iuduplicate aestivation of the calyx of Clematis Virgini- ana. 44G. Same of Clematis Viticella, the margins involute. 274 THE FLOWKR. corolla of Gentians, or outwards, as in that of Campanula (Fig. 443). When these plaits are laid over one another in a convolute manner, as in the unopened corolla of the Morning-Glory (Fig. 444) and Stramonium (Fig. 447, 448), the aestivation is said to be supervolute. 503. The direction of the spire or the overlap- ping of parts may be either from left to right, or from right to left ; and this direction is generally uniform. In indicating the direction, it is most natural to suppose the observer to stand before the flower-bud. DeCandolle, indeed, supposes the observer to occupy the centre of the flower, Avhich would reverse the direction ; but the former is the prevalent view. The direction is frequently re- versed in passing from the calyx to the corolla, sometimes with remarkable uniformity ; while again the two occur almost indifferently in many cases. The kind of aestivation, although often the same both in the calyx and corolla, — as in Parnassia (Fig. 381) and Elodea (Fig. 375), where both are quincuncially imbricated, — is as frequently different ; and the difference is often characteristic of families or genera. Thus, the calyx is valvate and the corolla convolute in all Malvaceae ; the calyx imbricated and the corolla convolute in Hypericum, in the proper Pink tribe, &c. Solitary exceptions now and then occur in a family. Thus, the corolla in Rosacea? is imbri- cated, so far as known, except in Gillenia, where it is convolute. In general it may be said, that the aestivation of the corolla is less con- stant than that of the calyx. 504. The Calyx. In treating of the general structure and diver- sities of the flower, we have already noticed the principal modifi- cations of the calyx and corolla, as well as many of the terms em- ployed to designate them ; which need not be here repeated. 505. The number of sepals that enter into the composition of a calyx is indicated by adjectives formed from the corresponding Greek numerals prefixed to the name ; as, disepalous, for a calyx of two sepals ; trisepalous, of three sepals ; tetrasepalous, of four ; pen- (asepalous, of five ; hexasepalous, of six sepals ; and so on. Very commonly, however, the Greek word for leaves, phylla, is used in FIG 447. Summit of the unexpanded corolla of Datura meteloides. 448. Transverse sec- tion of the same. THE CALYX AND COKOLLA. 275 such composition ; and the calyx is said to be diphyllous, triphyllous, tetraplnjllous, pentaphyllous, hexaphyllous, &c, according as it is com- posed of two, three, four, five, or six leaves or sepals respectively. These terms imply that the leaves of the calyx are distinct, or nearly so. When they are united into a cup or tube, the calyx was by the earlier botanists incorrectly said to be monophyllous (literally one- leaved) ; — a term which Ave continue to use, guarding, however, against the erroneous idea which its etymology involves, and bearing in mind that the older technical language in botany is founded upon external appearance, and not the real structure, as we now under- stand it. The correct term, calyx gamophyllous, is now coming into use : this literally expresses the true state of the case, and is equiva- lent to the phrase sepals united ; the degree of coalescence being in- dicated by adding " at the base," " to the middle," or " to the sum- mit," as the case may be. Still, in botanical descriptions, it is usual and ordinarily more convenient to regard the calyx as a whole, and to express the degree of union or separation by the same terms as those which designate the degree of division of the blade of a leaf (281 — 287) : as, for example, Calyx Jive-toothed, when the sepals of a pentaphyllous calyx are united almost to the top ; Jive-cleft, when united to about the middle ; Jive-parted, when they are separate almost to the base ; and Jive-lobed, for any degree of division less than five-parted, without reference to its particular extent. 506. The united portion of a gamophyllous calyx is called its tube ; the distinct portions of the sepals are termed the teeth, seg- ments, or lobes, according to their length as compared with the tube ; and the orifice or summit of the tube is named the throat. The calyx is said to be entire, when the leaves of the calyx are so com- pletely confluent that the margin is continuous and even. The terms regular and irregular (44G, 471) ai*e applied to the calyx or corolla separately, as well as to the Avhole flower. The counterpart term to calyx monophyllous or monosepalous, is polyphyllous or polysepalous (viz. of many leaves or sepals). This is equivalent to the phrase sepals distinct ; and does not mean, as the etymology might lead one to suppose, that they arc unusually numerous. 507. The Corolla has corresponding terms applied to its modifica- tions. When its petals are distinct or unconnected, it is said to be polypetalous ; when united, at least at the base, monopetalous, or more properly gamopetalous, as already explained. Various de- grees of such union are shown in Fig. 450 - 4G0. The united por- 276 THE FLO AVER. tions in the latter case form the tube of the corolla ; the distinct parts are the lobes, segments, &c. ; and the orifice is called the throat, just as in the calyx. The number of parts that compose the corolla is designated in the manner ah'eady mentioned for the calyx ; viz. a corolla of two petals is dipetalous ; of three, tripetalous ; of four, tetrapetcdous ; of five, pentapetalous ; of six, hexapetcdous ; of seven, hepta]jetalous ; of eight, octopetalous ; of nine, enneapetalous ; often, decapetalous. 508. Frequently the petals (and rarely the sepals) taper into a stalk or narrow base, analogous to the petiole of a leaf, which is called the claw (unguis) ; and hence the petal is said to be unguicu- late ; as in Crucifei-ous flowers (Fig. 405), the Pink family (Fig. 432), and Gynandropsis (Fig. 433), &c. ; the expanded portion, like that of the leaf, being distinguished by the name of the lamina, limb, or blade. 509. Some kinds of polypetalous flowers receive particular names, from the form or arrangement of their floral envelopes, especially of the corolla. They may be divided into the regular and the irregular, — terms which have already been defined (446, 471). Among the regidar forms we may mention the rosaceous flower, like that of the Rose, Apple, &c, where the five spreading petals have no claws, or very short ones ; the liliaceous, of which the Lily is the type, where the claws or base of the petals or sepals are erect, and gradually spread towards their summits ; the caryophyllaceous, as in the Pink and its allies (Fig. 449), where the five petals have long and narrow FIG. 449. Corolla of Soapwort, of five separate, long-clawed or unguiculate petals. FIG. 450. Flower of Gilia or Ipomopsis coronopifolia ; the parts answering to the claws of the petals of the last figure here all united into a tube. FIG. 451. Flower of the Cypress-A f ine ; the petals a little farther united into a five-lobed ppreading border. FIG. 452. Flower of the small Scarlet Morning-Glory, the five petals it is composed of per- fectly united into a trumpet-shaped tube, and a nearly entire spreading border. THE COROLLA. 277 claws, which are enclosed in the tube of the calyx ; and the cruciate, or cruciform, which gives its name to the Mustard family, where the four unguiculate petals, diverging equally from one another, are necessarily disposed in the form of a cross, as in the Mustard (Fig. 405). Among the irregular polypeta- /7/1 ^J— \ lous flowers, which are extremely varied in different families, the papilionaceous or but- terfly-shaped corolla of the Pulse family is the most familiar, and has already been illustrated (471, Fig. 392). 510. Several forms of the gamopetalous corolla, or gamophyl- lous calyx, have been distinguished by particular names. These are likewise divided into the regular, where their parts are equal in size, or equally united ; and the irregular, where their size or de- gree of union is unequal (471). Among the former are the cam- panulate or bell-shaped, as the corolla of the Harebell (Fig. 456), which enlarges gradually and regularly from the base to the summit ; the infundibuliform, or funnel-shaped, where the tube enlarges very gradually below, but expands widely at the summit, as in the corolla of Morning-Glory (Fig. 1035 and 452) ; tubular, where the form is somewhat cylindrical throughout, as in Trumpet Honeysuckle ; hypo- craterifarm (more correctly hypocraterimorphous), or salver-shaped, Rotate or wheel-shaped and five-parted corolla of the Bittersweet (Solarium FIR. 453. Dulcamara). FIR. 454. FIR. 455. FIR. 456. Wheel-shaped and five-cleft corolla of the common Potato. The almost entire and open bell-shaped corolla of a Ground Cherry (Physalis,). Campanulate corolla of the Harebell, Campanula rotundifolia. 45". Salver- shaped corolla of Phlox. 458. Labiate (ringent) corolla of Lamium ; a side view. 459. Per- sonate corolla of Antirrhinum. 460. Personate corolla of Linaria, spurred at the base. 24 278 THE FLOWEK. where the limb spreads at right angles with the summit of the more or less elongated tube, as in the corolla of Cypress-Vine (Fig. 451) and Phlox (Fig. 457) ; and rotate, or wheel-shaped, when a hypo- crateriform corolla has a very short tube, as in the Forget-me-not, Bit- tersweet (Fig. 453), and Potato (Fig. 454). 511. The principal irregular gamopetalous or gamophyllous forms that have received a separate appellation are the ligulate or strap- shaped, winch has already been explained (473), and the labiate or bilabiate. The latter, as already stated, is produced by the unequal union of the sepals or petals (473), so as to form an upper and a lower part, or two lips, as they are called, from an obvious resemblance to the open mouth of an animal (Fig. 458 - 460). This variety is al- most universally exhibited by the corolla of the Sage or Mint family ( which is therefore called Labiatte), as well as of several related families ; and the calyx is frequently bilabiate also, as in the Sage. And since, in the corolla of these families, two of the five petals enter into the composition of the upper lip, and three into that of the lower, this is necessarily inverted in the bilabiate calyx, three of the sepals combining to form the upper lip, and two to form the lower. 512. "When the upper lip is arched, as in the corolla of Lamium (Fig. 458), it is sometimes called the galea, or helmet. "When the two lips are thus gaping and the throat open, the corolla is said to be rinyent. When the mouth is closed, or partly so, by an elevated portion or protuberance of the lower lip, called the palate, as in the Snapdragon and Toadflax (Fig. 459, 460), the corolla is said to be personate, or masked. 513. In the Snapdragon, the base of the corolla is somewhat pro- tuberant, or saccate, on the anterior side ; in the Toadflax, the pro- tuberance is extended into a hollow spur. A projection of this kind is not uncommon, in various families of plants. One petal of the Violet is thus spurred or calcarate (Fig. 397) ; so is one of the outer petals in the Fumitory, and each of them in Dicentra (Fig. 370). So, also, one of the sepals is spurred or strongly sac-shaped in the Jewel- weed (Impatiens), and the Larkspur (Fig. 398) ; and all five petals take this shape in the Columbine. A monster of the Toadflax is occasionally found, in which the four remaining petals of the five which enter into its composition, affect the same irregularity, and so bring back the flower to a singular abnormal state of regularity. This was called by Linnajus Peloria ; a name which is now used to designate the same sort of monstrosity in different flowers. THE STAMKNS. 279 514. The petals are sometimes furnished with appendages on their inner surface, such as the crown at the summit of the claw in Silene (Fig. 378, 449), and the scales similarly situated on the gamopetalous corolla of the Comfrey, &c. These appendages some- times represent a circle of sterile and metamorphosed stamens ; but more commonly they seem really to belong to the petal. 515. As to duration, sometimes the floral envelopes are caducous, i. e. falling off when the blossom opens, as the calyx in the Poppy fam- ily and the corolla of the Grape- Vine (Fig. 384). More commonly they are deciduous, or fall after expansion, but before the fruit forms. When they remain until the fruit is formed or matured, they are persistent, which is often the case with the calyx, especially when it has a green color and foliaceous texture. When they persist in a dry or withering state, as the corolla of Heaths, Campanula, &c, they are said to be marcescent. 516. Besides serving as organs of protection, the sepals, when green, assimilate sap, and act upon the air like ordinary foliage (344, 345). The petals, like other uncolored (that is greenless) parts, do not evolve oxygen, but abstract it from the air, and give off carbonic acid ; in other words, they decompose assimilated matter, — a pro- cess which appears to be needful in flowering, and to subserve some important end at the time (3G8-373). The tissue of a petal is much the same as that of a leaf, except that it is much more delicate and the fibre-vascular system is generally reduced to slender bundles of a few spiral vessels, &c, which form its veins. Sect. VI. The Stamens. 517. The Stamens have already been considered in a general way (418). Before describing their structure more particularly, the principal terms which relate to their number, connection, and posi- tion may be mentioned. Most of these terms were devised by Lin- naeus as names of the classes of his Ai-tificial System of classification (Part II. Chap. IV.), founded mainly upon characters furnished by the stamens. Their number in a flower is accordingly expressed by the names of the eleven or twelve earlier Linnaean classes (990), put into adjective form. Thus, a flower with one stamen is said to be monandrous ; with two, diandrous ; with three, trimidrous ; with four, tetrandrous ; with five, pentandrous ; with six, hexandrous ; 280 THE FLOWER. with seven, heptandrous ; with eight, octandrous ; with nine, ennean- drous ; with ten, decandrous ; with twelve, dodecandrous. When more than twelve, and inserted on the calyx, they are isocandrous, or when inserted on the receptacle, polyandrous. 518. As to their union with each other, this may take place in various ways. Sometimes the filaments are combined, while the anthers are distinct. When thus united by their filaments into one set, they are said to be monadelphous ; as in the Lupine, &c. (Fig. 462) and Mallow. When united by their filaments into two sets, they ai'e diadel- phous, as in most plants of the Pulse family, where nine stamens form one set and the tenth is soli- tary (Fig. 461); and in Dicentra (Fig. 369 - 371), where the six stamens are equally com- bined in two sets. When united or ar- ranged in three sets or parcels, they are said to be triadelphous, as in the com- mon St. Johnswort ; or if in several, polyadelphous ; as in Linden. When stamens are united by their anthers into a tube or ring, they are said to be syn- genesious (Fig. 463, 464). This occurs in the Avhole vast order of Composite. Here the five filaments are distinct ; whereas in Lobelia, and also in the Melon and Gourd (Fig. 465, 466), both the filaments and the anthers are united ; that is, the stamens are monadelphous as well as syngenesious. 519. As to insertion, stamens are hypogynous (466) when borne on the receptacle, that is, when not adnate to any other organ ; FIG. 461. Diadelphous stamens (9 and 1) of a Pea. 462. Monadelphous stamens of a Lupine. FIG. 463. Five syngenesious stamens of a Composita. 464. The same, laid open. FIG. 465. Column of stamens, at once triadelphous and syngenesious, of the Gourd : the floral envelopes cut away. 466. A cross-section of the united anthers, nearly the natural size. 467. A sinuous anther of the Melon. THE STAMENS. 281 perigynoits (4G7) when borne on or adnate to any part of the calyx ; epipetalous, when borne on the corolla, as in the greater number of monopetalous flowers ; and epigynous (469), when borne on the ovary. In some cases the adnation proceeds further, and the stamens are inserted on, i. e. are consolidated with, the style, as in the Orchis family ; then they are said to be gynandrous (Fig. 4G8). 520. There are two cases in which inequal- ity in the length of the filaments is expressed by a technical term. Namely, the stamens are said to be didynamous when, being only four in number, they are in pairs, and one pair is 468 longer than the other ; as in Gerardia (Fig. 407), and in most flowers with a bilabiate corolla^p^nd they are tetradynamous when, being six in number, two are shorter than the remaining four, as in Mus- tard and all that family of plants with Cruciferous flowers (Fig. 406). 521. A stamen consists of its filament and its anther (418). The filament, being a mere stalk or support of the anther, is not an essential part ; it is to the anther what the petiole is to the blade of a leaf. Sometimes, therefore, it is wanting, when the anther is sessile. The anther is essential to a perfect stamen. But sometimes a stamen, or what stands in the place of one, is destitute of an anther, i. e. is sterile, as in Fig. 408 ; and also the upper one in Fig. 468, st, which is a sterile filament enlarged into a petal-like body. The true nature of the organ is known by its position. 522. Tlie Filament, although usually slender and stalk-like, assumes a great variety of forms : it is sometimes dilated so as to resemble a petal, except by its bearing an anther ; as in the transition states be- tween the true petals and stamens of the Water-Lily (Fig. 344). The filament is anatomically composed of a central bundle of spiral ves- sels or ducts, which represent the fibro-vascular system of the leaf, in the same state as in the petiole, enveloped by parenchyma ; the outer stratum of which forms a delicate epidermis. 523. The Anther, which is the essential part of the stamen, is usu- ally borne on the apex of the filament ; and commonly consists of two lobes, or cells (thecce), placed side by side, and connected by a prolongation of the filament, called the connectivum, or connective. FIG. 468. Stamens and style of a Cypripedium, united into one body or column: a, a, anthers : st. a sterile stamen : stig. the stigma. 24* 282 THE FLOWER. 524. The attachment of the anther to the filament presents three principal modes. 1st. When the base of the connective exactly corresponds with the apex of the filament and with the axis of the anther, the latter is termed innate, and rests firmly upon the summit of the filament, as in Fig. 469. 2d. When the lobes of the anther adhere for their whole length to a prolonga- tion of the filament, or to a broad connective (whichever it be called), so as to appear lateral, it is said to be adnate ; as in Magnolia, Lirio- dendron (Fig. 470), &c. Here the anther must be either extrorse or in- trorse. It is introrse, or tuiiied in- 4=9 4rj in wards, when it occupies the inner side of the connective, and faces the pistils, as in Magnolia ; but when the anther looks away from the pistils and towards the petals or sepals, it is said to be extrorse, or turned outwards, as in Iris, Liriodendron, and Asarum (Fig. 472). 3d. When the anther is fixed by a point near its middle to the apex of the filament, on which it lightly swings, it is said to be versatile ; as in all Grasses, in the Lily, and in the Evening Primrose (Fig. 471), &c. In this case, as in the preceding, the anther is said to be introrse, or incumbent, when it is turned towards the pistil, which is the most common way ; and extrorse, when it faces outwards. 525. The connective is often inconspicuous or wholly wanting, so that the lobes of the anther are directly in contact on the apex of the filament ; but it is commonly evident. It is often produced into an appendage at the tip of the anther, as in Magnolia and Liriodendron (Fig. 470), the Papaw (Fig. 956, where it forms a rounded top), and Asarum (Fig. 472). Appendages or processes from the back of the connective are seen in the stamens of the Violet and of many Ericaceous plants. i:i 526. Each of the two cells or lobes of the anther is marked with a lateral line or furrow, running from top to bottom ; this is the FIG. 469. A stamen of Isopyrum biternatum, with an innate anther 470. Stamen of Lirio- dendron, or Tulip-tree, -with an adnate extrorse anther. 471. Stamen of (Enothera glauca, with the anther fixed by its middle and versatile. FIG. 472. A stamen of Asarum Canadense, with an adnate anther. THE ANTHER. 2S3 suture, or line of dehiscence, by which the anther opens at maturity to discharge the pollen (Fig. 473). This line is for the most part exactly lateral in innate anthers ; hut it looks more or less evidently, and often directly, inward in introrse, and outward in extrorse anthers. In certain cases the cells of the anther open only at the summit, by a pore or hole, as in Py- rola (Fig. 474) and most Fricaceous plants. In the Whortleberry family each cell or lobe is commonly pro- longed into a tube, which opens only at the apex ( Fig. 391). In the Bar- berry (Fig. 475), and in nearly all plants of the Barberry family, the whole face of each anther-cell sepa- rates by a continuous line, forming a kind of door, which is attached at the top, and turns back, as if on a hinge : in this case the anthers are said to open by valves. In the Sassafras (Fig. 1114), and many other plants of the Laurel family, each lobe of the anther opens by two such valves, like trap-doors. 527. Sometimes the anthers are one-celled by the suppression of one lobe, being dimidiate, or reduced as it were to half-stamens, as in Gomphrenaor Globe-Amaranth (Fig. 478). But most one-celled anthers are the result of the confluence of the two cells into one. A comparison of the two-celled anther of Pent- stemon pubescens, where the two cells diverge below and are somewhat united at the top (Fig. 47 G) with the kidney-shaped one-celled anther of a Mallow, opening by a continuous line all round the margin (Fig. 477), shows how this result is brought about. As to anatomical structure, each lobe of the full-grown anther consists of an epidermal membrane, lined with a delicate fibrous tissue, and surrounding a cavity filled with pollen. This 528. FIG. 473. A stamen, with its anther, b, opening in the normal manner down the whole length of the outer side of each cell : a, the filament. FIG. 474. Stamen of a Pyrola ; each cell of the anther opening by a terminal orifice. FIG. 475. Stamen of a Barberry ; the cells of the anther opening by an uplifted valve. FIG. 476. A stamen of Pentstemon pubescens ; anther-cells slightly confluent. FIG. 477. Stamen of Mallow ; the two cells confluent into one, opening round the margin. FIG. 478. Anther of Globe Amaranth, of only one cell ; the other cell obliterated. 284 THE FLOWER. fibrous lining (a little of which is shown in Fig. 45, from the anther of Cobrea) is composed of simple or branching threads or bands, which formed the thickening deposit on the walls of large paren- chymatous cells ; all the membrane between the bands becoming ob- literated as the anther approaches maturity, the latter alone remain, as a set of delicate fibres. This fibrous layer gradually diminishes in thickness as it approaches the line of dehiscence of the cell, and there it is completely interrupted. These very elastic and hygro- metric threads lengthen or contract in different ways, according as the anther is dry or moist, and are thought to favor the egress of the pollen. The outer stratum of the wall of the anther in dry- ing contracts more than the inner, and so opens the cell, in many cases turning the walls inside out after dehiscence, as in Lilies and Grasses. 529. Of all the floral organs, the anther shows least likeness to a leaf. Nevertheless, the early development is nearly the same. Like the leaf, the apex is earliest formed, appearing first as a solid protuberance, and the anther is completed before the filament, which answers to the leafstalk, makes its appearance. At first, the anther is of a greenish hue, although at maturity the cells assume a differ- ent color, more commonly yellow. A transverse section of the form- ing anther shows four places in which the transformation of the paren- chyma into pollen commences, which answer to the centre of the four divisions of the parenchyma of a leaf, viz. the two sides of the blade, each distinguished into its upper and its lower stratum. So that the anther is primarily and typically four-celled ; each lobe being divided by a portion of untransformed tissue, stretching from the connective to the opposite side, which corresponds to the margin of the leaf and the line of dehiscence. This appearance is presented by a large number of full-grown anthers : but the par- tition usually disappears before the anther opens, when each lobe becomes single celled. The normal anther is consequently considered as two-celled. In Meni- spermum and Cocculus, however, the anther is strongly four-lobed externally, and each lobe forms a distinct 479 cell at maturity. 530. Viewed morphologically, therefore, the filament answers to FIG. 479. Plan of a stamen as answering to a leaf; the upper part of the anther cut away, and the summit of a leaf represented above it. THE POLLEN. 285 the petiole of a leaf; the anther, to the blade. The connective represents the midrib ; the lobes or cells of the anther represent the two symmetrical halves of the blade ; and the line of dehiscence is normally along the margins of the transformed leaf. What in the leaf would be cells of parenchyma develop as 531. Pollen. This usually powdery substance consists of grains, of definite size and shape, uniform in the same plant, but often very different in different species or families. The grains are commonly single cells, globular or oval in shape, and of a yellow color. But in Spiderwort they are oblong ; in the Cichory and Thistle tribes many-sided (Fig. 485) ; in the Musk-plant spirally grooved (Fig. 480) ; in the Mallow family (Fig. 483) and the Squash and Pump- kin, beset with bristly projections, &c. The pollen .of Pine (Fig. 486), as well as that of the Onagracerc (Fig. 487, 489), is not so simple, but appears to consist of three or four blended cells ; that of all true Ericacere evidently consists of four grains or cells united (Fig. 488). The most extraordinary shape is that of Zostera, or the Eel-grass of salt-water, in which the grains (destitute of the outer coat) consist of long and slender threads, which, as they lie side by side in the anthei-, resemble a skein of silk. 532. Pollen-grains are usually formed in fours, by the division of the living contents of mother cells first into two, and these again into two parts, which, acquiring a coat of cellulose, become specialized cells (36). As the pollen completes its growth, the walls of the mother cells are usually oblit- erated. But sometimes the enclosing cells persist, and collect the FIG. 480-489. Forms of pollen : 4S0, from Mimulus mosehatus : 481, Sicyos: 482, Echi- nocystis : 483, Hibiscus : 4S4, Lily : 485, Cichory : 4S6, Pine : 48", Circasa : 4SS, Kalmia : 489, Evening Primrose. 286 THE FLOWER. pollen-grains into coherent masses of various consistence, as is re- markably the case in the Orchis and Milkweed families (Fig. 543, &c). Such pollen-masses are sometimes termed pollinia. 533. The threads, resembling cobweb, that are loosely mixed with the pollen of the Evening Primrose, are the vestiges of obliterated mother cells. 534. Pollen-grains have two coats. The outer coat, called the extine, is comparatively thick, and often granular or fleshy. This is later formed than the inner, and by a kind of secretion from it : to it all the markings belong. The inner coat, or intine, which is the proper cell-membrane, is a very thin and delicate, transparent and colorless membrane, of considerable strength for its thickness. The pollen of Zostera and of some other aquatic plants is destitute of the outer coat (531). 535. The cavity enclosed by the coats is filled with a viscid liquid, rich in protoplasm, Avhich often appears slightly turbid under the higher powers of ordinary microscopes, and, when submitted to a magnifying power of about three hundred diameters, is found to contain a multitude of minute particles (fovillce), the larger of which are from the four-thousandth to the five-thousandth of an inch in length, and the smaller only one fourth or one sixth of this size. The smaller exhibit the constant molecular motion of all such mi- nute particles when suspended in a liquid and viewed under suffi- cient magnifying power. When wetted, the grains of pollen prompt- ly absorb water by endosmosis (37), and are distended, changing their shape somewhat, and obliterating the longitudinal folds, one or more in number, which many grains exhibit in the dry state. Soon the more extensible and elastic inner coat inclines to force its Avay through the Aveaker parts of the outer, especially at one or more thin points or pores ; sometimes forming a projection of considerable length, when the absorption is slow and the exterior coating tough. If the absorption continues, the distention soon overcomes the resist- ance of the elastic inner coat, which bursts, and the contents are dis- charged. 536. When fresh, living pollen falls upon the stigma, however, which is barely moist, it does not burst, but the inner membrane is slowly projected, often through particular points, clefts, or openings of the outer coat, in the form of an attenuated transparent tube (Fig. 537-547), filled with its fluid contents, and which penetrates the naked and loose cellular tissue of the stigma, and buries itself in THE PISTILS. 287 the style. This is not a mechanical protrusion, but a true growth, the materials for which are supplied by nourishment imbibed from the stigma and style. Its further course and the office it subserves will be considered after the structure of the pistil is made known. (Sect. IX.) Sect. VII. The Pistils. 537. The Pistils (419) occupy the centre of the flower, and ter- minate the axis of growth. Linnaeus established the orders of his Artificial System mainly upon the pistils, and this introduced a se- ries of terms expressive of their number in a flower, analogous to those used for the number of stamens (517). Thus a flower with a single pistil is said to be monogynous ; with two, digynous ; with three, trigynous ; with four, tetragynous ; with five, pentagynous ; and so on : when more numerous or indefinite, the flower is polygynous. 538. It is comparatively seldom that the pistils are exactly equal to the petals or sepals in number ; they are sometimes more numer- ous, and arranged in several rows upon the enlarged or prolonged receptacle, as in the Magnolia, the Strawberry, &c, and perhaps more frequently they are reduced to less than the symmetrical num- ber, or to a single one. Yet often what appears to be a single pistil is not so in reality, but a compound organ, formed by the union of two, three, or a greater number of simple pistils ; these organs being subject to coalescence in the same way as the stamens (518) and the petals (507, 462). 539. A simple and complete pistil, as already described (420), is composed of three parts : the Ovary, or seed-bearing portion ; the Style, or tapering portion, into which the apex of the ovary is pro- longed ; and the Stigjia, usually situated at the summit of the style, consisting of a part, or sometimes a mere point, of the latter, divested of epidermis, with its moist cellular tissue exposed to the air. The ovary, which contains the ovules, or bodies which are to become seeds, is of course a necessary part of the pistil ; the stigma, which receives from the anthers the pollen (531) by which the ovules are fertilized, is no less necessary ; but the intervening style is no more essential to the pistil than the filament is to the stamen, and is there- fore not uncommonly wanting. In the latter case, the stigma is sessile upon the apex of the ovary. In Tasmannia it actually occu- pies the side of the ovary for nearly its whole length, and is sepa- 2«3 THE FLOWER. rated from the line to which the ovules are attached only by the thickness of the walls : it is nearly the same in our Schizandra (Fig. 493), another plant of the Magnolia family. The style some- times proceeds from the side, or even from near the apparent base of the ovary ; as in the Strawberry (Fig. 428). 540. When the pistil is single, or when several coalesce into one, it will necessarily terminate the axis, and appear to be a direct con- tinuation of it. When there are two pistils in the flower, they al- ways stand opposite each other (so that if they coalesce it is by their inner faces) ; and are either lateral as respects the flower, that is, one on the right side and the other on the left, in a plane at right angles to the bract and axis (444), as in the Mustard family, the Gentian family, and a few others ; or, more commonly, anterior and posterior, one before the axis and the other before the bract of the axillary flower. When they accord in number with the sepals or petals, they are either opposed to or alternate with them; and the two positions in this respect are sometimes found in nearly related genera, so as to baffle our attempts at explaining the cause of the difference. In Pavonia, for example, the five pistils are opposite the petals ; in Malvaviscus and Hibiscus, alternate with them. In Sida (when five) they stand opposite the petals ; in Abutilon, opposite the sepals. 541. Pistils occur under such a diversity of forms, and exhibit such various complications, that the plan of their structure and the distinction between simple and compound pistils require to be well understood. Commencing, therefore, with the most natural forms, and proceeding gradually to the more complex or disguised, we first consider 542. The Simple Pistil, and the way in which it answers to a leaf. A simple pistil answers to a single leaf. A compound pistil answers to two or more leaves combined, just as a monopetalous corolla answers to two or more petals, or leaves of the flower, united into one body. As to its morphology, the botanist regards a simple pistil as consisting of the blade of a leaf, curved inwards until its margins meet and unite, forming in this way a closed case, or pod, which is the ovary. So that the upper face of the altered leaf answers to the inner surface of the ovary, and the lower, to its outer surface. And the ovules are borne on what answers to the united edges of the leaf. The tapering summit, rolled together and prolonged, forms the style, when there is any ; and the edges THE SIMPLE PISTIL. 289 of the altered leaf turned outwards, either at the tip or along the inner side of the style, form the stigma. This will be clearly un- derstood on comparing Fig. 342 and Fig. 491, which are pistils transversely divided, with Fig. 490, a leaf curved inwards until its margins nearly meet, and with Fig. 492, a simple pistil of Caltha or Marsh-Marigold which has matured, split open along the inner side to discharge the seeds it bore, and spread out into the shape of a leaf. 543. The line formed by the union of the margins of the leaf is called the Inner or Ventral Suture, and always looks towards the axis of the flower. This is a true suture, or seam, as the word denotes. The opposite line, answering to the mid- rib, is sometimes apparent as a thickened line, and is termed the Outer or Dorsal Suture. The ovules or young seeds are borne (in all ordinary cases at least) on the inner suture, or some part of it ; that is, on what answers to the united margins of the infolded and transformed leaf. The part in the cell of the ovary to which the ovules are attached, and which is commonly more or less enlarged or projecting when the ovules are numerous, is named 544. The Placenta. As this corresponds with the ventral suture, and is in fact a part of it, or a cellular growth from it, it always belongs next the axis of the flower ; as is evidently the case when two, three, or more pistils are present. Each placenta necessarily consists of two parts, one belonging to each margin of the transformed leaf. It therefore is frequently two-lobed, or of two diverg- 494 495 ing lamellae (Fig. 342). This shows why the ovules are apt to occupy two longitudinal rows, as in FIG. 490. A leaf infolded, to illustrate the theory of the formation of the pistil. FIG. 491. Pistil of Isopyrum biternatum, cut across ; the inner or ovule-bearing side turned towards the observer. FIG. 492. Ripe pistil of Caltha palustris, after opening and discharging the seeds. FIG. 493. Vertical section of a pistil of Schizandra coccinea ; a side view. 494. Tistil of Hydrastis. 495. Pistil of Actsea rubra, cut across, so as to show the interior of the ovary (the ventral suture turned towards the observer). 25 290 THE FLOWER. the figure last cited, and in Fig. 491, 495, &c, one row belonging to each margin of the leaf. A simple pistil, accordingly, can have only one placenta ; but that is structurally double. 545. So a single pistil can have only one style and one stigma. But as the stigma answers to the margins of the apex of the leaf, this must also be double in its nature. And this is evidently the case in the Peony and Isopyrum (Fig. 491), in the Tulip, as well as in Fig. 493 - 495, and in almost all cases in which the stigma extends down the inner face of the style, as it frequently does. Such unilateral stigmas Ave accordingly take to be the typical form ; and say that, while the united margins of the transformed leaf which compose the ventral suture are turned inwards into the cell of the ovary to bear the ovules, in the simple style they are exposed external- ly to form the stigma. Where the stigma is terminal, or occupies only the apex of the style, we suppose that these margins are in- folded in the style also, and form in its interior the loose conducting tissue through which a communication is established between the stigma and the interior of the ovary. 546. The ovary of a simple pistil obviously can have but one cavity or cell ; except from some condition out of the natural order of things. But the converse does not hold true : all pistils of a sin- gle cell are not simple. Many compound pistils are one-celled, as will presently be explained. 547. A leaf or member of the gynrecium then, when separate, forms a simple pistil ; when combined with others, it makes part of a compound pistil. It is convenient to have a name which shall desig- nate a single pistil-leaf, whether occurring as a distinct simple pistil, or as an element of a compound pistil. For this purpose the name of Caepel has been devised. A carpel is either a simple pistil, or is one of a circle of leaves which compose a compound pistil. When the pistils are distinct from each other, they are said to be apocarpous ; when united into one body, syncarpous. This union produces a 548. Compound Pistil. All degrees of union of the carpels may be observed, from the coalescence of the lower part of their ovaries, their summits remaining separate (as in Fig. 49 G), or from the com- plete union of the ovaries into one body,-the styles remaining sepa- rate (as in Fig. 497), to the complete coalescence of the styles also (Fig. 498), and even of the stigmas (Fig. 499), into one body. It is evidently the same as if two or more pistils (in Fig. 497 - 499, three THE COMPOUND PISTIL. 291 pistils) were pressed together as they grew and consolidated more or less completely into one. And in this, the most normal case, Ave have as the result compound pistils 549. With two or more Cells and Axilc Placenta. For it is evident that, if the contiguous parts of a whorl of three or more closed car- pels cohere, the resulting compound ovary will have as many cavi- ties, or cells, as there are carpels in its composition, and the placentae (one in the inner angle of each carpel) will all he brought together in the axis of the compound pistil. And the partitions, or Dissep- iments, which divide the compound ovary into cells, manifestly consist of the united contiguous portions of the walls of the carpels. These necessarily are composed of two layers, one belonging to each carpel ; and in ripe pods they often split into the two layers. True dissepiments must always be equal in number to the carpels of which the compound pistil is composed. 550. In certain cases, indeed, there are addi- 50 ° tional partitions, or false dissepiments. These are commonly projec- FIG. 49C. Pistil of a Saxifrage, composed of two carpels or simple pistils united below, but distinct above ; cut across both above and below. FIG. 497. Pistil of common St. Johnswort, of three united ovaries ; their styles distinct. FIG. 498. The same of another species of St. Johnswort (Hypericum prolificuin), the styles also united into one, which, however, split apart in the fruit. FIG. 499. Pistil of Tradescantia or Spiderwort, even the three stigmas united into one. The ovary in all cut across to show the internal structure. FIG. 500. Cross-section of a flower of Flax ; each of the five cells of the ovary partly divided by an imperfect false partition from the back. 292 THE FLOWER. DOo. tions or growths from the dorsal suture ; whether in a simple pistil (as that of most species of Astragalus, Fig. 805), or from the back of each proper cell of a compound pistil, as in the Service-berry, the Blueberry, and the common Flax (Fig. 500). 551. "We have considered only the case of compound pistils of two or more cells in the ovary. But compound pistils also not unfre- quently occur 552. Witll Only one Cell. And of these there are two kinds to be noticed, those with axile, and those with parietal jplacentce. That is, in the first, the ovules are borne in the axis or centre of the ovary, either at the base or on a column which occupies the centre ; in the second, they are borne on some part of the parietes or walls of the ovary. The first, viz. With a Free Central Placenta, is found in the Primrose, Purslane (Fig. 889), and Pink families (Fig. 432, 501, 502). In the Pink family this evidently results from the ob- literation of the dissepiments (as many as there are styles or stigmas) ; and vestiges of these may be de- tected at an early stage, and sometimes at the base of the full-grown ovary ; while certain plants of the same family, of otherwise identical structure, retain the par- titions even in the ripe pod. In other instances, as in Diona^a, Thrift, &c, this is doubtless a modification of parietal placentation, with ovules produced only at the bottom. This brings us to the case of compound one- celled pistils 554. With Parietal PlaceiltBB, that is, with the placenta? borne on the sides or parie- tes of the ovary, as in the Poppy, Caper, Cistus or Rock-Rose (Fig. 507), Violet, Sun- dew (Fig. 510), and Currant families, and many others To comprehend this per- FIG. 501. Vertical section through the compound tricarpellary ovary of a plant of Spergu- laria rubra, showing the free central placenta. 502. Transverse section of the same. FIG. 503-505. Diagrams illustrating parietal and free central placentation. 503. Cross- section of a tricarpellary ovary, with a free central placenta, produced by the obliteration of the dissepiments. 501. Section of an ovary with three strictly parietal placentae. 505. Same, except that there are incomplete partitions. THE COMPOUND PISTIL. 293 fectly, we have only to imagine two, three, or any number of pistil- leaves (like Fig. 490), arranged in a circle, to unite Avith one another by their contiguous edges, either without any intro- flexion or infolding at all (Fig. 504), or at least without their infolded edges having reached the cen- tre and united there (Fig. 505, 506). The combina- tion is accordingly much like that by which petals unite to form a monopetalous corolla, only the edges of the pistil-leaves are always turned in, Avhere they bear the ovules. Such an ovary may well be compared Avith the valvate un- opened calyx of Clematis, the margins of the sepals more or less turned in- wards (Fig. 445). Every gradation is found between axile and parietal pla- 507 centation, especially in the St. Johns- 506 wort family (Fig. 508, 509) and in the Gourd family. 555. An ovary with parietal placentae is necessarily one-celled; except it be divided by an anomalous partition, such as is found in Cruciferous plants, and in the Trum- pet Creeper. 556. It Avill be seen that parietal placenta) are necessarily double, like the placenta of a simple ovary, or of each carpel of a compound several- celled ovary ; but Avith this difference, that in these the two portions belong to the two margins of the same carpel ; Avhile in parietal placentae they are formed from the coalescent margins of two adjacent carpels. 557. The number of carpels of which a compound ovaiy consists is indicated by the number of true dissepiments when these exist ; or by the number of placenta?, when these are parietal ; or by the number of styles or stigmas, when these are not Avholly united into one body. Thus a simple pistil has a single cell, a single placenta, FIG. 506. Plan of a one-celled ovary with three parietal placentae, cut across below ; the upper part showing the top of the three leaves it is composed of, approaching, but not united. FIG. 507. Ovary of Ilelianthemum Canadense, cut across, showing the ovules on three parietal placenta;. FIG. 50S. Transverse section of the ovary of Hypericum graveolens ; the three large placentas meeting in the centre, but not cohering. 509. Similar section of a ripe pod of the same ; the placentas now evidently parietal. 25* 294 THE FLOWER. and a single style. A pistil of two carpels may be two-celled, with two placentae, two styles, or two stigmas, &c* * There are, however, some exceptions which qualify these statements : — 1. Each placenta being a double organ (556), it occasionally happens that the two portions are separated more or less, as in Orobanchaceous plants, where a dicarpellary ovary appears on this account to have four parietal placenta; ; either approximate in pairs (as in our Cancer-root, Conopholis), or equidis- tant (as in Aphyllon). 2. Analogous to this is the case where the two constituent elements of the stigma (the only essential part of the style) separate into two half-stigmas, as is partially seen in Fig. 494, 495. The stigma, no less than the placenta, belongs to the margins of the infolded leaf (545), these margins being ovuliferous in the ovary and stigmatiferous in the style ; as Mr. Brown, the most profound botanist of this or any age, has clearly shown. These two constituent portions of the style or stigma occasionally separate, cither entirely or in part, as in Euphorbiaceous plants, in Grasses, and especially in Drosera (Fig. 510), where there are consequently twice as many nearly distinct styles as there are parietal placenta; in the compound ovary If the two component parts of the style of each carpel were reunited into one, in the usual manner, their number le, Aggre- gate, Accessory or Anthocarpous, and Multiple Fruits. 593. Simple Fl'UitS are those which result from the ripening of a single pistil, whether Avith or without a calyx or other parts adnate to it. This division comprises most of the kinds of fruit which have distinctive names, and those of the other classes are mainly aggre- gations or combinations of these. 594. Simple Fruits may be conveniently divided into Fleshy fruits, Stone fruits, and Dry fruits. The leading kind of the first division is 595. The Berry (Bacca), an indehiscent fruit which is fleshy or pulpy throughout. The grape, gooseberry, currant, cranberry, and tomato are familiar examples. 596. The Ilesperidium (orange, lemon, and lime) is merely a berry with a leathery rind. 312 THE FRUIT. 597. TllC Pepo, or Goiird-frilit, is also a modification of the berry, with a hard rind, which occurs in the Gourd family. The cucum- ber, melon, and squash are familiar illustrations. A Pepo is an indehiscent, externally firm and internally pulpy fruit, composed usually of three carpels, and with an adnate calyx. In the ovary it is either one-celled with three broad and revolute parietal placentas, or these placenta?, borne on slender dissepiments, meet in the axis, enlarge, and spread, unite with their fellows on each side, and are reflected to the walls of the pericarp, next which they bear their ovules (Fig. 560, 561). As the fruit enlarges, the seed-bearing placentas usually cohere with the walls, and the partitions are oblit- erated, giving the appearance of a peculiar abnormal placentation, which only the study of the ovary readily explains. 598. A Pome, such as the apple, pear, and quince (Fig. 809, 812), is a fruit composed of two or more carpels, either papery, cartilagi- nous, or bony, usually more or less involved in a pulpy expansion of the receptacle or disk, and the whole invested by the thickened and succulent tube of the calyx. It may be readily understood by comparing a rose-hip with an apple. The calyx makes the princi- pal thickness of the flesh of the apple, and the whole of that of the quince. 599. Tlic Drupe, or Stonc- Frilit, is a one-celled, one or two seeded indehiscent fruit, with the inner part of the peri- carp (endocarp, or putamen, 588) hard or bony, while the outer (exocarp,ov sorcocarp) is fleshy or pulpy It is the latter which in these fruits so readily takes an increased development in cultivation. The name is strictly FIG. 560. Section of the ovary of the Gourd. 561. Diagram of one of its constituent carpels. FIG. 562. A'ertical section of a peach. 563. An almond ; where the exocarp, the portion of the pericarp that represents the pulp of the peach, remains thin and juiceless, and at leDgth separates by dehiscence from the endocarp, or shell. ITS KINDS. 313 applicable only to fruits produced by the ripening of a one-celled pistil; as the plum, peach (Fig. 562), &c. ; but it is extended in a general way to such fruits with two or more bony 564 cells enclosed in pulp, as that of the Dogwood, &c. 600. The raspberry and blackberry (Fig. 564) are composed of a great number of miniature stone- fruits, or drupelets, as they might be called, in struc- ture resembling cherries (Fig. 5G5), aggregated upon an elongated receptacle. 601. Dry Fruits may be either dehiscent or indehis- cent (589). Of indehiscent dry fruits one of the simplest kinds is 602. The Achenium, or Akene (Fig. 566-573). This includes all one- seeded, dry and hard, indehiscent and seed- like, small fruits, such as are popularly taken for naked seeds. But that they are true pistils or 566 ovaries ripened is evident from the styles or stigmas they bear, or from the scar left by their fall ; and a section brings to view the seed within, provided with its own proper integuments. The name has been restricted to the seed- like fruits of simple pistils, as those of the Buttercup (Fig. 566, 567), Anemone, Clematis, and Geum (where the persist- FIG. 564. Magnified vertical section of half of a blackberry. 565. Section of one of the grains, or drupekts, more magnified. FIG. 566. Achenium of a common Buttercup, enlarged. 567. Vertical section of the same, showing the seed within. FIG. 568. Achenium of Mayweed (no pappus). 569. That of Cichory (its pappus a shal- low cup). 570. Of Sunflower (pappus of two deciduous scales). 571. Of Sneczeweed (Hele- nium), with its pappus of five scales. 572. Of Sow-Thistle, with its pappus of delicate downy hairs. 573. Of the Dandelion, its pappus raised on a long beak. 27 314 THE FRUIT. ent style usually remains on the fruit as a long tail), and the minute grains of the strawberry (Fig. 559). But it may be extended, as is now generally done, to all such one-celled seed-like fruits result- ing from a compound ovary, and even when invested with an adnate calyx-tube. Of this kind is the fruit of all Composite (Fig. 568- 573). Here the tube of the calyx is incorporated with the surface of the ovary, and its limb or border, obsolete in some cases (Fig. 568), in others appears as a crown (Fig. 569), cup, a set of teeth or of scales (Fig. 570, 571), or as a tuft of bristles or hairs (Fig. 572, 573), &c, called the pappus. In the Lettuce and Dandelion (Fig. 573), the achenium is rostrate, i. e. its summit is extended into a slender beak. 603. A Utricle is the same as an achenium, only with a thin and bladdery loose pericarp, like that of Goosefoot and Amaranth (Fig. 574, 575). The thin coat commonly bursts irregularly, discharging the seed. In the true Amaranths it opens by a circular line, and the upper part falls as a lid, converting the fruit into a small pyxis (619). 604. A Caryopsis or Grain differs from the last in hav- ing the seed completely filling the cell, and its coat firmly consolidated throughout with the very thin peri- carp, as in wheat, Indian corn, and other cereal grains (Fig. 622 - 624). Of all fruits this is the kind most likely to be mistaken for a seed. 605. A Nut is a hard, one-celled and one-seeded, indehiscent fruit, like an achenium, but larger, and usually produced from an ovary of two or more cells with one or more ovules in each, all but a single ovule and cell having disappeared during its growth (586) ; as in the Hazel, Beech, Oak (Fig. 576, 1166), Chestnut, Cocoa-nut, &c. The nut is often enclosed or sur- rounded by a kind of involucre, termed a Cupule ; as the cup at the base of the acorn, the bur of the chestnut, and the leaf-like covering of the hazel-nut. 606. A Samara or Key-fruit is a name applied to a nut, or achenium, having a winged apex or margin ; as in the Birch, Elm (Fig. 578), FIG. 574. Utricle of Chenopodium album, or common Goosefoot. 575. Utricle, or pyxis, of an Amaranth. FIG. 576. Acorn (nut) of White Oak, with its cup or cupule. ITS KINDS. 315 and Ash (Fig. 577). The fruit of the Maple consists of two such fruits belonging to one flower, united by their bases (Fig. 787). 607. Dehiscent Fruits, or Pods, are distinguishable into a those consisting of a simple pistil, and those resulting |}|jj|j| from a compound pistil. 608. Of those originating from simple pistils, the principal kinds are the Follicle and the Legume. These may be taken as the type, of simple fruits. 609. A Follicle is a pod formed of a simple pistil, and dehiscent by the ventral or inner suture alone ; as in the Milkweed, Larkspur, Columbine, Peony, and Marsh-Marigold (Fig. 579). "When it opens widely, the pistil may be said to revert to its natural state of a leaf, and it often looks much like one, as in Fig. 492. 610. A Legume is a pod formed by the ripen- 579 ing of a simple pistil which dehisces by both sutures, and so divides into two valves or pieces, as in the Bean and Pea (Fig. 580). This being the ordinary fruit of the Pulse family, accordingly named Leguminosce (or Leguminous plants), the name has been extended to it in descriptive botany, in all cases, whatever the form, and whether dehiscent or not. The legume will be found to exhibit no small diversity in this large fam- ily (799). Among its forms is one termed 611. A Loment. This is a legume divided transversely into two or more one-seeded joints, which usually fall apart at maturity (Fig. 581). Commonly these joints remain closed, as in Desmodium ; sometimes they split into two valves, as in Mimosa. 612. A Capsule is the pod, or dehiscent fruit, of any compound pistil. When regularly dehis- cent, as already stated (591), the pod splits lengthwise into pieces or valves. 613. A capsule, necessarily consisting of two or more carpels or FIG. 577. Samara of White Ash. 578. Samara of American Elm. FIG. 579. Follicle of Caltha palustris, the Marsh-Marigold. FIG. 5S0. Legume of a Sweet Pea, already dehiscent. 581. Loment of a Tick-Trefoil or Desmodium. 316 THE FRUIT. simple pistils united into one body, will normally dehisce in one of two ways. Namely, either the carpels will separate at the line of junction, thus resolving the pod into its constituent elements ; or else, these parts remaining united, each cell will open on the back by a splitting of the dorsal suture. The former constitutes 614. Septicidal Dehiscence (Fig. 582, 584), so named because the capsule splits through the septa or partitions (dissepi- ments), each one separating into its two constituent layers, one belonging to each carpel. This occurs in Azalea and its allies, in St. Johnswort, &c. The car- pels, thus becoming separate, in these cases open down their inner suture, 582 like a follicle, and discharge the seeds. When the cells are only one-seeded, after separating septicidally, they often remain closed and fall away separately, as in Mallow, Vervain (Fig. 985), &c. Such closed or nearly closed cells or car- pels of a compound pistil are termed cocci. 615. Loculicidal Dehis- cence is that in which the splitting opens into the loculaments (in Latin, locidi) or cells ; that is, each carpel dehisces by its dorsal suture (Fig. 583, 585), as in Iris, the Lily, Hibiscus, Evening Prim- rose, &c. The dissepiments here are necessarily borne on the mid- dle of the valves. 616. In the Violet, &c. we have the loculicidal, and in several kinds of St. Johnswort the septicidal, plan of dehiscence in one- celled capsules ; the placenta? (answering to the partitions) being borne in the former upon the middle of the valves ; while in the latter each placenta is split in two, and one half borne on each mar- gin of a valve. FIG. 582. Dehiscent capsule of Elodea, enlarged, showing septicidal dehiscence. FIG. 583. Dehiscent capsule of Iris, showing loculicidal dehiscence ; the lower part cut across, showing the dissepiments borne on the middle of the valves. FIG. 584. Diagram (in cross-section) of septicidal, and, 585, of loculicidal, dehiscence. ITS KINDS. 317 617. Septifragal Dehiscence is a modification of either the loculicidal or the septicidal, in which the valves fall away, leaving the dissepi- ments behind attached to the axis. Fig. 586 is a diagram representing this in a case of loculicidal opening. Fig. 587, from the common Morn- ing-Glory, is this modifica- tion of the septicidal mode. 618. Instead of splitting into separate pieces, the sutures of the pericarp sometimes open for a short distance at their apex only, as in Cerastium and some other Chickweeds, in Tobacco (Fig. 1050), and in the Primrose (Fig. 943) ; or by mere pores, as in the Poppy. The pod of the Snap- dragon opens by the bursting of a hole towards the top of each cell, not corresponding, perhaps, with any suture. Another anomalous mode of dehiscence, namely, the circu??icissile, characterizes 619. The Pyxis or Pyxidium, a pod which opens by a circular hor- izontal line cutting off the upper part as a lid. The fruits of the Plantain, Henbane, Amaranth (Fig. 575, which is otherwise a utricle), Pimpernel, and Purslane (Fig. 588) are of this kind. 620. A Silique is a slender two-valved capsule, with two parietal placentae, from which the valves separate in dehiscence ; as in plants of the Cruciferous or Mustard family (Fig. 589), to the fruit of which the term prop- erly belongs. Usually a false partition is stretched across between the two placenta 3 , rendering the pod two-celled in an anomalous manner. 621. A Silicle or Pouch is merely a short silique, its length not more than twice its breadth ; as that of Shep- herd's-Purse, Candytuft, &c. 622. Aggregate Fruits are those in which a cluster of carpels, all belonging to one flower, are crowded on the receptacle into one mass, as in the raspberry and .blackberry taken as a whole (Fig. 564), where the constituent fruits, or ripened carpels, FIG. 5S6. Septifragal modification of loculicidal, and. 5S7, of septicidal, dehiscence. FIG. 5S8. Pyxis or pod of Purslane, the top separating as a lid. FIG. 5S9. Silique of Cardamiue, in dehiscence. 27* 318 THE FRUIT. are little drupes ; also the cone-like fleshy fruit of Magnolia, where the component carpels are a sort of drupaceous follicles, at length opening on the back and summit ; and the dry cone of the Tulip-tree, where each carpel forms a sort of samara. None of these aggregate fruits have special names in ordinary use. In descriptive botany it is sufficient to state the kind of fruit the carpels themselves form, and their mode or degree of aggregation. 623. Accessory or Antliocarpous Fruits are those of which the most conspicuous portion, although often appearing like a pericarp, neither belongs to the pistil nor is organically united Avith it. The apparent berry of Gaultheria, in which a succulent free calyx invests a dry pod and appears to form the real fruit (Fig. 912-914) has already been adverted to (583) ; and the calyx of Shepherdia is similar, forming what appears to be the sarcocarp of a drupe, although it is really free from the achenium it encloses. So, also, the apparent achenium or nut of Mirabilis, or Four-o'clock, is the thickened and indurated base of the tube of a free calyx, which contracts at the apex and encloses the true pericarp as a utricle or thin achenium, but does not cohere with it. The rose-hip, a hollow calyx-tube lined with a hollow receptacle (Fig. 429), and the strawberry (Fig. 428, 558, 559), consisting of a conical enlarged receptacle bearing many minute achenia, may also be regarded as forms of antliocar- pous fruit. G24. Multiple Or Collective Fruits are those which result from the aggregation of several flowers into one mass. The simplest of these are those of the Partridge-Berry (Mitchella) and of some species of Honeysuckle (Fig. 859), consisting of the ovaries of two blossoms united into one double berry. The more usual sorts are such as the pine-apple, mulberry, and the fig. These are, in fact, dense forms of inflorescence, with the fruits or floral envelopes matted together or coherent with each other ; and all or some of the parts become succulent. The grains of the mulberry (Fig. 593, 594) are not the ovaries of a single flower, like those of the blackberry which it super- ficially resembles (Fig. 564), but belong to as many separate flow- ers ; and the pulp of these pertains to the floral envelopes instead of the pericarp. So that the mulberry is an anthocarpous (623) as well as a multiple fruit. The pine-apple is very similar ; only the ovaries or pericarps never ripen any seeds, but all are blended, with the floral envelopes, the bracts, and the axis of the stem they thickly cover, into one fleshy and juicy mass. The fig (Fig. 590 -592) ITS KINDS. 319 differs from the pine-apple in having this succulent axis or receptacle 591 590 593 on the outside. It may be compared with such an anthocarpous fruit as a rose-hip (Fig. 429). It results from a multitude of flow- ers concealed in a hollow flower-stalk, if it may be so called, which becomes pulpy and edible when ripe ; and thus the fruit seems to grow directly from the axil of a leaf, without being preceded by a blossom. The minute flowers concealed within, or some of them, ripen their ova- ries into very small achenia, which are commonly taken for seeds. The principal form of multiple fruit which has received a substantive name is 625. The Strobile or Cone, a scaly multiple fruit, resulting from the FIG. 590- A young fig. 591. Vertical section of the same, enlarged. 592. A small slice of the same, more magnified, showing the flowers on the inside. FIG. 593. A young mulberry. 594. One of the grains, magnified, showing it to be a pis- tillate flower, with a succulent calyx embracing the ovary 595. The same, less magnified, the succulent calyx cut away. FIG. 596. Strobile or Cone of a Pitch Pine, Pinus rigida. 597. Inside view of one of the scales, showing one of the seeds, and the place from which the other, 598, has been detached. 320 THE SEKD. ripening of some sort of catkin. The name is applied to the fruit of the Hop, where the large and thin scales are bracts ; but it more especially belongs to the Pine or Fir cone, the peculiar fruit of Co- nifera (Fig. 596), the scales of which are open carpels (560), bear- ing two or more naked seeds upon their upper or inner face (Fig. 597). A more or less fleshy and closed cone, such as that of Taxo- dium, and especially that of Juniper (Savin, Red Cedar, &c), which at maturity imitates a berry, has been termed a Galbalus. CHAPTER XI. OF THE SEED. Sect. I. Its Structure and Parts. 626. The Seed, like the ovule (561), of which it is the fertilized and matured state, consists of a Nucleus, or kernel, usually en- closed within two Integuments. 627. Its Integuments, &C- The outer, or proper seed-coat, corresponding to the ex- terior coat of the ovule, is variously termed the Epispeem, Spermoderm, or more com- monly the Testa (Fig. 599, b). It varies greatly in texture, from membranaceous or papery to crustaceous or bony (as in the Papaw, Nutmeg, &c), and also in form, being sometimes closely applied (conformed) to the nucleus, and in other cases loose and cellular (as in Pyrola, Fig. 927, and Sullivantia, Fig. 843), or ex- panded into wings (as in the Catalpa and Trumpet-Creeper, Fig. 601), which render the seeds buoyant, and facilitate their dispersion by the wind ; whence winged seeds are only met with in dehiscent fruits. The wing of the seed of Pines (Fig. 598) is a part of the surface of the scale or carpel to which it is attached, and which separates with it. For the same purpose, the testa is sometimes FIG. 599. Vertical magnified section of the (anatropous) seed of the American Linden : a. the hilum ; b, the testa ; c , the tegmen ; d, the albumen ; e, the embryo. 600. Vertical section of the (orthotropous) seed of Ilelianthemum Canadense : a, the funiculus. ITS STRUCTURE AND PARTS. 321 provided with a tuft of hairs at one end, termed a Coma ; as in Epilobium and Milkweed (Fig. 602). In the Cotton-plant, the whole surface of the seed is covered with long wool. It should likewise be noticed, that the integument of numerous small seeds is furnished with a coating of small hairs containing spiral threads (one form of which is represented in Fig. 44), and usually appressed and con- fined to the surface by a film of mucilage. "When the seed is moistened, the mucilage softens, and these hairs spread in every direction. They are often ruptured, and the extremely attenuated elastic threads they contain uncoil, and are protruded in the greatest abundance and to a very considerable length. This minute mechanism subserves an obvious purpose in fixing these small seeds to the moist soil upon which they lodge, when dis- persed by the wind. Under the microscope, these threads may be observed on the seeds of most Polemoniaeeous plants, and on the achenia of Labiate and Composite plants, as, for example, in many species of Senecio, or Groundsel. In Peony the testa becomes fleshy or baccate ; in Magnolia it imitates a drupe. 628. The inner integument of the seed, called the Tegmen or Exdopleura, although frequently very obvious (as in Fig. 599, c), is often indistinguishable from its being coherent with the testa, and is sometimes altogether wanting. 629. The stalk of the seed, as of the ovule, is called the Fu- niculus (Fig. 600, a). The scar left on the face of the seed, by its separation from the funiculus at maturity, is termed the Hil-um. The chalaza and rhaphe, when present, are commonly obvious in the mature seed, as well as in the ovule (564-568), and the name and relations of these several parts in the seed are the same as in the ovule. Also the terms orthotropous, anatropous, eampylotrojious, &c, originally applied to the ovules, are extended to the seeds which result from them ; so that we may say, Seeds anatropous, as well as Ovules anatropous, &c. 630. Aril or Al'illus. Some seeds are furnished with a covering, (usually incomplete and of a fleshy texture,) wholly exterior to their proper integuments, arising from an expansion of the apex of the FIG. 601. The winged peed of Trumpet-Creeper. FIG. 602. Seed of Milkweed (Asclepias Coruuti), with its coma or tuft. 322 THE SEED. seed-stalk, or funiculus, or of the placenta itself when there is no manifest seed-stalk. This is called the Aril. It forms the pulpy envelope of the seed of Podophyllum, Euonymus, and Ce- lastrus, or it appears as a mere lateral scale in Turnera, or as a tough and lacerated body, known by the name of mace, in the Nutmeg. In the White Water-Lily it is a thin and delicate cellular bag, open at the end (Fig. G03). The Aril does not appear in the ovule, but is developed subse- 603 quent to fertilization, during the growth of the seed. Of the same or similar nature is the Caruncle found at the hilum in Polygala, forming a loose lateral appendage. Strictly speaking, it is to be distinguished from the Strophiole (like that of Euphor- bia), which is a cellular growth from the micropyle ; but the two are not well discriminated. An analogous cellular growth takes place on the rhaphe of the Bloodroot, of the Prickly Poppy, and of Dicen- tra, forming a conspicuous crest on the whole side of the seed. 631. The Nucleus, or Kernel of the seed, consists of the Albumen, when this substance is present, and the Embryo. 632. The Albumen, which has also been termed the Perisperm or the Endosperm, has already been described (125) as the floury part of those seeds in which an amount of nourishment for the germi- nating plantlet is stored up outside of the embryo. This was called by Gartner the albumen of the seed, from some fancied anal- ogy with the white of an egg as to situation or function ; — an un- fortunate term, on account of its liability to be confounded with the quaternary chemical substance of the same name (357), one of the forms of proteine. Being in general use, the term cannot now well be discarded. 633. The Albumen of the seed consists of whatever portion of the tissue of the ovule persists, and becomes loaded with nutritive mat- ter accumulated in its cells, — sometimes in the form of starch- grains principally, as in wheat and the other cereal grains ; some- times as a continuous, often dense, incrusting deposit, as in the cocoa- nut, the date, the coffee-grain, &c. When it consists chiefly of starch-grains, and may readily be broken down into a powder, it is said to be farinaceous, or mealy, as in the cereal grains generally, in buckwheat, &c When a fixed oil is largely mixed with this, it becomes oily, as in the seed of the Poppy, &c. ; when more compact, but still capable of being readily cut with a knife, it isjles/iy, as in FIG. 603. A seed of the White Water-Lily, with its sac-like arillus, magnified. THK ALBUMKN AND EMBRYO. 323 the Barberry, &c. ; when it chiefly consists of mucilage or vegetable jelly, as in the Morning-Glory and the Mallow, it is said to be muci- laginous ; when it hardens more, and becomes dense and tough, so as to offer much resistance to the knife, as in the Coffee, the Blue Cohosh, &c, it is corneous, that is, of the texture of horn. Between these all gradations occur. Commonly the albumen is a uniform deposit. But in the nutmeg, as also in the seeds of the Papaw (Fig. 658), and of all plants of the Custard-Apple Family, it presents a wrinkled or variegated appearance, owing to numerous transverse divisions, which are probably caused by inflections of the innermost integument of the seed : in these cases the albumen is said to be rumi- nated. The albumen may originate from new tissue formed either within the embryo-sac (579), which is probably the more common case ; or in the nucleus of the ovule exterior to the embryo-sac, which is certainly the case in the Water-Lily and its allies, and in Saururus ; for here the thickened embryo-sac persists within or at one extremity of the copious albumen ; or both kinds may coexist. When this is the case, the outer albumen may be distinguished as the perisperm, and the inner as the endosperm. G34. Seeds provided with albumen (as in Fig. 599, 600, 605, 606, 609, 610-616, 622, &c.) are said to be albuminous; those destitute of it (as in Fig. 607, 629, 110, 120, &c.) are exalbuminous. The comparative amount of the albumen, and its relation to the embryo in various seeds, may be seen on inspection of many of the subjoined figures. 635. The Embryo, or Germ, being an initial plantlet or individual, is of course the most important part of the seed : to its production, protec- FIG. 604. Seed of a Violet (anatropous), enlarged: a, hilum or scar ; b, rhapbe ; c, chalaza. FIG. 605. Vertical section of the same, showing the straight embryo in the axis of the mealy- albumen. FIG. 606. Vertical section of the (orthotropous) seed of Buckwheat, showing the embryo folded round in the mealy albumen. FIG. 607. Vertical section of the (anatropous) seed of Elodea Virginica, the embryo com- pletely filling the coats. FIG. 608. Seed of Delphinium tricome (anatropous), enlarged ; a, the hilum ; b, the rhapbe ; c, the chalaza. 609. Vertical section of the same : c, the chalaza ; d, the testa ; e, the tegmen ; /, the albumen ; g-, the minute embryo near the hilum, a. 324 THE SEED. tion, and support all the other parts of the fruit and flower are sub- servient. It becomes a plant by the mere development of its parts : it therefore possesses, in a rudimentary or undeveloped state, all the essential organs of vegetation, namely, a root, stem, and leaves. Its general structure and development have already been explained in considerable detail (118 - 130). G36. In albuminous seeds it is naturally the smaller and its parts the less developed in proportion to the amount of albumen, and the 6io 612 en 6i6 several organs are developed or even formed in germina- tion. In exalbumi- nous seeds, where the embryo con- stitutes the whole kernel, its several parts are ordina- rily conspicuous, although they are often more or less disguised by thickening; as the cotyledons in the Almond (Fig. 108) and Cherry (Fig. Ill), and especially in the Pea (Fig. 118), the Acorn (Fig. 120), the Horsechestnut (Fig. 630), and the like. 637. The parts of the embryo, as already illus- trated (120) are the Radicle, the Cotyledons, and the Plumule. The radicle is the axis, or rudimen- tary stem, — the first internode of the axis (121, 157), from the lower extremity of which the root is produced, while the other bears the cotyledons, i. e. the leaves of the first node ; and the plumule is the bud which crowns the summit of the radicle. 638. Owing to the mode of its formation (580), the radicle of the FIG. 610. Vertical section of the seed of a Peony, showing a small embryo near the base of the copious albumen. 611. The embryo, detached, and more magnified. FIG. 612. Section of a seed of Barberry, with a straight embryo in the axis of the albu- men. 613. Its embryo, detached. FIG. 614. Section of a Potato-seed, showing the embryo coiled in the albumen. 615. Its embryo, detached. FIG. 616. Section of the seed of Mirabilis or Four-o"clock, showing the embryo coiled round the outside of the albumen. 617. Its embryo, detached, and partly spread out. FIG. 618. Embryo of the Pumpkin, with its short radicle and large and flat cotyledons, seen flatwise. 619. A vertical section of the same, viewed edgewise. THE EMBRYO. 325 embryo is always near to and points towards the micropyle of the seed, viz. to what was the orifice of the ovule; and if the embryo be straight (as in Fig. 605), or merely partakes of the curvature of the seed, the cotyledons point to the opposite extremity of the seed, that is, to the chalaza. The position of the radicle as respects the hilum varies with the different kind of seed. In the orthotropous form, as in Helianthemum (Fig. 600) and Buckwheat (Fig. 606), the radicle necessarily points directly away from the hilum. In the anatropous form, as in the seed of the Lin- den (Fig. 599) and Violet (Fig. 604, 605), the extremity of the radicle is brought to the immediate vicinity of the hilum ; and so it is, although in a different way in the campylotropous seed (Fig. 620, 621) ; while in the amphitro- pous, the radicle points away from the hilum laterally, at a right angle to the funiculus. As the nature of the ovule and seed may usually be ascertained by external inspection, so therefore the situa- tion of the embryo within, and of its parts, may often be inferred without dissection. But the dissection of seeds is not generally a difficult operation. 639. The position of the embryo as respects the albumen, when that is present, is various. Although more commonly in the axis, it is often excentric, or even external to the albumen, as in all Grasses and cereal Grains (Fig. 622-624), in Polygonum (Fig. 1111), &c. When external or nearly so, and curved circularly around the albu- men, as in Goosefoot, Chickweed (Fig. 621), and Mirabilis (Fig. 616), it is said to be peripheric. When bent or folded in such a FIG. 620. Campylotropous seed of the common Chickweed (Stellaria media), magnified. FIG. 621. Section of the same, showing the embryo coiled around the outside of albumen. FIG. 622. Vertical section of a grain of Indian Corn, passing through the embryo : c, the cotyledon ; p, the plumule ; r, the radicle. (A highly magnified portion of the albumen, which makes up the principal bulk of the grain, is shown in Fig. 70, p. 54.) 623. Similar section of a grain of Rice. 624. Vertical section of an Oat-grain : a, the albumen ; c, the cotyledon ; p, the plumule ; and r, the radicle of the embryo. 28 326 THE SEED. way that the radicle lies along the edges of the cotyledons, the latter are said to be accumbent (Fig. 700) ; or when the radicle rests against the back of one of them, or in j:>roxirnity to it (Fig. 705), they are incumbent. 640. The direction of the embryo with respect to the pericarp is also particularly noticed by systematic writers ; who employ the terms ascending, or radicle superior, when the latter points to the apex of the fruit ; descending, or radicle inferior, when it points to its base ; centripetal, when the radicle is turned towards the axis of the fruit ; centrifugal, when turned towards the sides ; and vague, when it bears no evident or uniform relation of the kind to the pericarp. 641. As to the number of its cotyledons, or the degree of com- plexity or simplicity of the embryo, the principal types have already been considered (128). The plan of the embryo in Exogenous plants is to have a pair of opposite cotyledons ; that is, the embryo is dicotyledonous, and such plants are denominated Dicotyledo- nous Plants. 642. A modification of this plan occurs in Pines and most other Coniferre, in which the cotyledons are increased to three, four, six, or even to fifteen, in a whorl (Fig. 133, 134) ; and this embryo of highest complexity is called polycotyledonous. The embryos of some Leguminous or Cruciferous plants are occasionally found, with three cotyledons, as an accidental deviation. 643. But in all Endogenous plants only one cotyledon appears, i. e. only one seed-leaf on the primary node ; if two or more rudi- mentary leaves are present, they are alternate, and all but the first belong to the plumule. Here the em- bryo is monocotyledonoui, and hence % I \ / \ Endogens are also termed Monocoty- ledonous Plants. The monocoty- ledonous embryo does not usually pre- sent a manifest distinction into radicle, v ^ \_1/ cotyledons, and plumule, as the dicoty- ledonous ; but often appears like a ho- mogeneous and undivided cylindrical or club-shaped body, as in Iris FIG. 625. Seed of Triglochin palustre ; the rhaphe, leading to the strong chalaza at the eummit, turned towards the eye. 626. The embryo detached from the seed-coats, showing the longitudinal chink at the base of the cotyledon ; the short part below is the radicle. 627. Same, with the chink turned laterally, and half the cotyledon cut away, bringing to view the plumule concealed within. 628 A cross-section through the plumule, more magnified. THE EMBRYO. 327 (Fig. 131) and Triglochin (Fig. 626). In the latter, however, close inspection reveals a vertical slit or chink just above the radicular extremity, through which the plumule is protruded in germination. If the embryo be divided parallel with this slit, the plumule is brought into view ; as in Fig. G27. If a horizontal section be made at this point (as in Fig. G28), the cotyledon is found to be wrapped around the enclosed plumule, sheathing it, much as the bud and the 3-ounger parts of the stem are sheathed by the bases of the leaves in most monocotyledonous plants. The plumule is more manifest in Grasses, especially in the cereal grains, and more complex, ex- hibiting the rudiments of several concentric leaves, or of a strong bud, previous to germination (Fig. 622-624, and 126-128). In many cases, however, no distinction of parts is apparent until ger- mination commences ; as in the Onion, Iris (Fig. 131), &c. G-44. In several Dicotyledonous plants one cotyledon is smaller than the other, viz. the inner one, when the embryo is coiled or folded. And in all the species of Abronia this cotyledon is wanting, so that the embryo becomes tech- nically monocotyledonous. In the Dodder, a genus of leafless parasitic plants of the Convolvu- lus family, the embryo also is entirely destitute of cotyledons (Fig. 148). Here these organs are suppressed in an embryo of considerable size ; but in most such parasites, the embryo is very minute, as well as reduced to the greatest degree of simplicity, and seems to remain until germination in a very rudimentary state. 645. Sometimes the two cotyle- dons of a dicotyledonous embryo are consolidated, or more or less coherent by their contiguous faces into one mass, when they are said to be conferruminate, as in the Horsechestnut, Buckeye (Fig. 629, 630), and the Chestnut. In these, as in other embryos with very thick cotyledons, the latter are FIG. 629. Section of the seed of a liuckeye. 630. A Buckeye in germination. 328 THE SEED. necessarily hypogceous in germination (124, 126), that is, they re- main underground, enclosed within the coats of the seed, yielding their abundant store of nourishment to the radicle and the plumule ; and the first leaves that appear are those of the plumule. Sect. II. Germination. 646. Germination is the initial act of growth, by which the embryo in a seed develops into a plantlet. The steps of the early growth have already been sufficiently explained in an early part of this vol- ume (119-132). 647. The seeds of some plants (such as the Red Maple) germi- nate shortly after falling to the ground ; those of most other plants not until the next year, or even later. How long seeds may retain the power of germinating is uncertain, and is extremely variable in different species and families. Those of many plants under ordinary circumstances can rarely be made to grow after two or three years ; some will germinate pretty well after several years keeping ; and the seeds of certain Leguminous plants have been known to germi- nate when sixty years old. But the current accounts of wheat, &c. being raised from grain taken from ancient mummies, circumstan- tially authenticated as some of them appear to be, must be received with the greatest misgiving, if not with entire incredulity. One of the most probable cases of germination of ancient seeds on record is that given by Dr. Lindley, of some Raspberries, " raised in the gar- den of the Horticultural Society from seeds taken from the stomach of a man, whose skeleton was found thirty feet below the surface of the earth, at the bottom of a barrow which was opened near Dorches- ter. He had been buried with some coins of the Emperor Hadrian ; and it is therefore probable that the seeds toere sixteen or seventeen hundred years old." Most seeds, when buried deep in the soil, where they are subject to a uniform and moderate temperature, and removed from the influence of the air and light, may be in a favorable state for the preservation of vitality, and would be likely to germi- nate when brought to the surface after a considerable interval. But the possibility of mistake or of collusion must be more thoroughly eliminated before a case of such extraordinary tenacity of life, under conditions in some respects very unfavorable, can be considered as well established. GERMINATION. 329 648. The conditions requisite to germination are exposure to moisture and to a certain amount of heat, varying from 50° to 80° (Fahrenheit) for the plants of temperate climates, to which must be added a free communication with the air. Direct light, so essential to subsequent vegetation, is unnecessary, and generally unfavorable, to germination. The degree of heat required to excite the latent vitality of the embryo is nearly uniform in the same species, but widely different in different plants ; since the common Chickweed will germinate at a temperature not far above the freezing-point of water, while the seeds of many tropical plants require a heat of 90° to 110° (Fahrenheit) to call them into action, and are often exposed to a considerably higher temperature. Seeds are in the most favorable condition for germination in spring or summer, when loosely covered with soil, which excludes the light while it freely admits the air, moistened by showers, and warmed by the rajs of the sun. The water which is slowly absorbed softens all parts of the seed ; the embryo swells, and bursts its envelopes, or the elon- gating radicle is protruded from them, and all the parts grow or unfold in the manner already described, each organ in its proper medium, the root being developed in the soil, and the stem and leaves in the air. 649. The nourishment which the embryo requires during germi- nation is furnished by the starch, &c. of the albumen (682), when this substance is present in the seed ; or by starchy or other nutri- tive matter accumulated in its own tissue (636, 123). But as starch is insoluble in cold water, certain chemical changes are necessary to bring it into a fluid state, so that it may nourish the embryo. These changes are incited by the proteine or neutral azotized products (354), which are largely accumulated in the seed, either in the albumen or in the embryo itself, and which take the initiative in all the transformations of vegetable matter (27). In the germinating seed, just as in growth from a bulb or tuber, the changes essentially consist in the transformation of the starch, first into dextrine, or gum, and thence into sugar, a part of which is destroyed by resolu- tion, first into acetic acid, and finally into carbonic acid and water, with the abstraction of oxygen from the air, and the evolution of heat (349, 370-373), while the remainder is rendered directly sub- servient to the groAvth of the plantlet. The reason why light, so essential to subsequent growth, impedes or prevents incipient ger- mination, becomes evident when we remember that it incites the 28* 330 REPRODUCTION IN decomposition of carbonic acid, and the fixation of carbon by the plant (344 — 350) ; while germination is necessarily attended by an opposite transformation, namely, the destruction of a portion of or- ganized matter, with the evolution of carbonic acid.* In germina- tion, as in any other act in which matter is transformed or trans- ferred, there is a certain expenditure of force and loss of organized material. The plantlet is obliged to decompose and destroy a part of the starch or other material provided for its initial growth, in order that it may transform the rest into dextrine and sugar, and this again into cellulose or the material of the new cells formed in its growth. 650. The study of the seed, and of the development of the em- bryo it contains into a plantlet, completes the cycle of A^egetable life in the higher grade of Phamogamous plants, and brings us back to our starting-point (118, 119). CHAPTER XII. OF REPRODUCTION IN CRYPTOGAMOUS OR FLOWERLESS PLANTS. * 651. The lower grade of Cryptogamous or Flowerless Plants (Chap. II. Sect. I.) would now require to be considered, both as to the vegetation and their reproduction. But the plan of structure in each principal Cryptogamous family is so peculiar, and the organs of fructification especially so diverse, that their morphology cannot be presented under one common type, as in Pha?- nogamous vegetation. Each great family or group would have to be separately treated, and with much fulness of illustration, to make * Seeds may casually germinate while attached to the parent plant, especially such as arc surrounded with pulp, like those of the Cucumber and Melon. The process is liable to commence in wheat and other grain, when protracted warm and rainy weather occurs at the period of ripening ; and the albumen becomes glutinous and sweet, from the partial transformation of the starch into dextrine and sugar. In the Mangrove, which forms dense thickets along tropical coasts, germination habitually commences in the pericarp while the fruit remains on the tree ; and the radicle, piercing the integuments which enclose it, elongates in the air ; such a plant being, as it were, viviparous. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 331 the subject intelligible to tbe unpractised student. This can hardly be done in so elementary a work as the present, but requires a sepa- rate treatise. The student who has intelligently studied the present volume up to the present point, is prepared for the more difficult study of the structure of Cryptogamous plants, in the only general work of the kind that has yet appeared in the English language, viz. Berke- ley's Introduction to Cryptogamic Botany. An enumeration of the Cryptogamous orders, with a brief notice of their structure and sub- ordinate divisions, may be found in the systematic part of the pres- ent work. A slight sketch of their grades of development as to vegetation has already been given (97-113). We here attempt to present merely a very brief and general account of their plan of reproduction, divested as far as possible of technical terms. 652. Taken collectively, we distinguish this lower series of the vegetable kingdom by negative characters only ; saying that these plants do not bear true flowers (consisting essentially of stamens and pistils), and accordingly do not produce seeds, or bodies consisting of a distinguishable embryo plantlet, developed in an ovule through fertilization by pollen. Their spores (97), or the bodies produced in their fructification by which they are jn-opagated, and which there- fore answer to seeds, are single cells, at least in most cases. These, as they germinate in the soil, or whatever medium they live in, un- dergo a development at the time of their germination which has been compared with that of the embryonal vesicle (579) during its devel- opment into the embryo in the ovule ; and by growth directly give rise to the plant. 653. It was once thought probable, that these spores were pro- duced, and were capable of developing into the plant without being fertilized by other cells answering to pollen ; or at least that this was the case in all the lower orders, such as Algas and Fungi, and in some of the highest, such as Ferns. But the sagacious Linna?us, by nam- ing them Cryptogamous plants (i. e. plants with concealed organs of reproduction) seems to have recorded his belief that they were really bisexual, or furnished with two sorts of organs, the fertilizing and the fertilized. A series of important discoveries, for the most part of recent date, have proved this to be so, — have made known a true fecundation in numerous species of every Cryptogamous order, and in their lowest as well as their highest forms, thus leaving no doubt of its universality. The apparatus and the processes of reproduction, however, are wonderfully varied in the different groups of Cryp- 332 REPRODUCTION IN togamous plants. A few examples may be adduced, illustrative of the principal modes, beginning with the simplest plants. 654. Reproduction in Plants of a Single Cell (100). All such simple one-celled plants as Protococcus and the like (Fig. 79 - 83, 18 - 22), Desmidiaceas and Diatomaceae, are freely propagated by cell-multi- plication (33 - 3G), — the division of their protoplasm or whole living mass into bodies which directly become new cells like the parent, — or by original cell-formation in their interior (29). This is non- sexual reproduction, and essentially answers to the well-known prop- agation of Phoenogamous plants by buds, bulbs, offsets, &c. It is probable that this may not go on indefinitely in any plant. At any rate, not only do all the higher plants propagate in a different way, viz. by flowers, producing seeds, but probably all plants of the lower grade also have a sexual reproduction in some form or other. It is certainly the case in many one-celled plants, and in others almost equally simple in structure. As in Phamogainous plants, sexual reproduction essentially depends upon the mingling of the materials of two distinct cells (as the pollen-cell and the embryonal vesicle, 579) ; and these cells in the lowest forms of vegetation represent individual plants. The simplest mode of such reproduction in the lowest plants, and that longest known, is what has been termed 655. Conjugation. This is the mode in which two vast tribes of microscopic one-celled aquatic plants, the Desmidiaceaa and Diato- maceoe, are reproduced. They multi- ply rapidly, and apparently without Jimit, by successive division into two equal parts, which separate, each be- coming like the original. But at length two of these individuals, being en- dowed with the power of movement, come into contact ; the firm or often silicious cell-wall ruptures or gives way in a definite manner at the place of junction, and the whole contents of the two conjugating cells or individu- als are commingled into one mass of protoplasm, &c. ; this soon has a coat of cellulose formed around it, FIG. 631. Magnified individual of Closterium aeutum, after Ilalfs. 632. Two individuals more magnified, in conjugation ; their cells opening one into the other, and the contents min- gled ; in 633, condensing ; in 634, collected and formed into a spore. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 333 and is new a spore, which when it grows begins a new series of in- dividuals developed by successive division. 656. In Algae consisting of a Single Row of Cells one tribe presents the same mode of reproduction, and the various species of Zygnema or Spirogyra, found in almost every pool of fresh water at different times in spring and summer, afford the readiest illustrations of conjugation, which low powers of the microscope suffice to exhibit. These green threads when magnified are seen to consist of single rows of cylindrical cells joined end to end. The cells being all alike and equally capable of conjugation, each is as it were an individual. At a certain season, a protuberance appears on the corresponding parts of certain cells of two adjacent threads ; the budding growth continues until the two come into contact ; the intervening walls are then absorbed, opening a free communication between the cavities of the two cells ; mean- while the green matter and protoplasm, before arranged in some definite shape in each species (more commonly in one or more spiral bands), break up into a granular mass floating in the water of the cell ; this all passes over from one cell to the other, — sometimes to the one plant and sometimes to the other in adjacent cells, — and is mingled with the similar contents of the cell which receives it ; and the united product is condensed into a green protoplasmic mass, which, acquiring a coat of cellulose, be- comes a new cell or spore, in due time germinating into a iicav plant. 657. In reproduction by conjugation, the two cells or individuals concerned are alike ; one is as much the fertilizer or the fertilized as the other. But the clear distinction of sexes which all the higher Cryptogamous no less than Phasnogamous plants exhibit, is also mani- fested in those of the simplest structure, viz. in plants consisting of single cells, or of rows or clusters of similar and essentially inde- pendent cells. That is, even these afford examples of FIO. 635. Magnified view of two conjugating filaments of Zygnema, showing all the stages of the process by which the cells from two filaments form each a corresponding protuberance, these come into contact, the intervening walls are absorbed, and the contents pass from one cell into the other, condense, acquire an investing membrane, and so form a spore : the stages are represented from above downwards ; a completed spore is seen at the bottom, on the right. 334 REPRODUCTION IN 658. Direct Fertilization of Spores by Spermatozoids from an Anthc- l'idium ; the latter answering to the anther, or essential part of the stamen, of Phsenogamous plants. Colin * has shown that even Volvox — an undoubted vegetable, consisting of microscopic one- celled plants of rounded form, grouped into a spherical colony — has a true sexual propagation, like that of the higher green Alga?, some of the individuals or cells of the sphere producing antheridia or fer- tilizing cells, while others produce spores, or bodies which become such on being fertilized by the antheridia, which alone renders them capable of germination. A good general idea of bisexual reproduction in the simplest Algaj may best be obtained from a brief abstract of Avhat has lately been discovered by Pringsheim and Cohn in two or three common species of comparatively easy investigation. 659. Vaucheria is a genus of several species of green Alga?, con- sisting of simple but indefinitely branching cells (Fig. 89). In fruc- tification, the whole contents of the more or less enlarged extremity of some of the branches, or of a special projection from the side of the cell, separate from the general contents of the plant, con- dense into a globular green mass (Fig. 89 a), and become a spore, which at length escapes by a rupture of the walls (Fig. 90), moves freely about in the water for some hours, then fixes itself, and ger- minates, elongating directly into a thread-like and at length branch- ing plant, like the parent. Here there appears, and was generally thought to be, reproduction without fecundation. Vaucher, however, more than half a century ago, noticed one or more horn-shaped pro- jections in the vicinity of the spore-bearing portion, which he sus- pected to be the analogues of the anther. Nothing had been found to verify this view until the year 1854, when Pringsheim, of Berlin, discovered the fecundation and verified this conjecture. The horn- shaped body is an antheridium, or the analogue of the anther. It produces myriads of extremely minute corpuscles, of oblong shape, and furnished with a bristle or cilia at each end, by the vibration of which they move freely in the water. These are spermatozoids (so called from their obvious resemblance to the spermatozoa of ani- mals), and the analogues of pollen. At the proper time the anthe- ridium bursts at the summit, and discharges the spermatozoids ; at this time the wall of the projection which contains the spore likewise opens ; numbers of the free-moving spermatozoids find their way * In Comples Rendus, vol. 43, 185G, and Ann. Set. Nat. scr. 4, vol. 5, p. 323. CRYPTOGAIMOUS OR FLOWERLESS PLANTS. 33a into the opening and into contact with the forming spore, or even penetrate its substance ; it being an amorphous mass, coated with protoplasm only. But, as a consequence of fecundation by one or more spermatozoids, a wall of cellulose is presently formed on its surface, converting it into a proper specialized cell or spore.* 660. JEdogonium is a genus of simple Alga? of the Conferva tribe, consisting of a row of cylindrical cells placed end to end, as in Fig. 639. Some of these cells, usually shorter than the rest, become tumid, and, without conjugation, have their whole green contents transformed into a spore resembling that of Zygnema (Fig. 635) and Vaucheria (Fig. 90). The fertilization of this spore has re- cently been discovered by Pringsheim.f He ascertained that other cells of the same little plant produce a great number of minute ovoid bodies, which he names Androspores : these escape by the opening of the mother cell, moving about freely by the vibration of a crown of cilia attached near the smaller end. One or more of these androspores fix themselves by the smaller end upon the surface of the cell in which a large ordinary spore is forming, or in the vicinity, and germinate there, growing longer and narrower at the point of attachment, while near the free end a cross partition forms, and some- times another, making one or two small cells ; this is the true anthe- ridium ; for in it a crowd of spermatozoids are formed, also endowed with motivity by means of vibratile cilia. Now the top of the an- theridium falls off as a lid, the spermatozoids escape ; the spore-cell at this time opens at the top ; one of the spermatozoids enters the opening, its pointed end foremost ; this becomes stationary upon or slightly penetrates the surface of the young spore, into which its contents are probably transferred, by rupture or by endosmosis, and a coat of cellulose is then, but not till then, deposited upon it, com- pleting its organization as a spore. This spore, as in the preceding cases, in due time germinates, and grows directly into a plant like the parent. But in Bolbochsete, according to Pringsheim, and in Sphreroplea, as investigated by Cohn,j the spore in germination converts its contents by successive division into a large number of small, oval or oblong bodies, furnished with two long cilia on a short * Pringsheim, in the Proceedings of the Royal Academy of Sciences, Berlin, March, 1855, and Ann. Sci. Nat. ser. 4, vol. 3, p. 363. t Op. supra cit. May, 1856, and Ann. Sci. Nat. ser. 4, vol. 5, p. 250. t Op. supra cit. May, 1855, and Ann. Sci. Nat. 1. c. p. 186, pi. 12, 13. 336 REPRODUCTION IN beak at one end, and which from their extreme resemblance to ani- malcules and their lively movements are called Zoospores. And these zoospores germinate by elongation and the formation of trans- verse partitions into adult thread-like plants, consisting of a row of cells. The whole contents of the cells of some adult individuals of Sphaeroplea are formed into large green spores, as yet without a coat ; those of different individuals give rise to myriads of slender sperma- tozoids, moving by means of a pair of cilia fixed at the narrow end. These escape from the parent cell through a small perforation which now appears, enter the spore-bearing cells of the fertile plant through a similar perforation, play around the spores, and at length one or more of them drives its pointed extremity into their naked surface ; after which, fertilization being accomplished, a thick coat of cellulose is deposited to complete the spore. 6G1. That in the Fucaceoe or olive-green SeaAveeds, the highest tribe of Algo?, the large spores are fecundated by spermatozoids, or minute lively-moving cells produced in antheridia, was demonstrated by Thuret in the year 1850.* And in more recent memoirs | he has shown that the fertilization takes place through direct contact of the spermatozoids with the naked surface of the unimpregnated spore, then having only a protoplasmic coating ; and that these spores will not develop unless so fertilized. Through the researches of Thuret and others, antheridia are now well known in the remaining or rose-red series of Algoe, although their spermatozoids are not known to be endowed with motivity. The same appears to be the case with Lichens, the bodies described by Itsigsohn,j being probably of the nature of spermatozoids or fertilizing cells. In the vast family of Fungi there arc similar indications of antheridia and spermatozoids, but the fecundation is not yet clearly made out. GG2. Fertilization by Spermatozoids of a Cell in a Pislilidium, which becomes a Sporangium. In all the foregoing cases, the spores them- selves are the subjects of direct fertilization. But in Mosses, Liverworts, &c. (in which the two kinds of organs have long been recognized and their functions to some extent understood), the contents of the antheridium act upon an organ which, in conse- * Ann. Sci. Nat. scr. 3, vol. 14 and 16, 1850-1. See Harvey, Nereis Bor. Amer. in Smithsonian Contributions, 1852, &c. t Op. cit. ser. 4, vol. 2 and 3, 1854, 1855. J In Botanische Zeilung, 1850. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 337 quence of fertilization, develops into a sort of pod, the Sporangium or Spore-case, filled with a multitude of spores which receive no in- dividual fecundation ; this organ, from its general analogy to the pistil, has been termed a Pistillidium. The antheridia of Mosses and the like occur either in the axils of the leaves, or collected into a head at the summit of the stem. They are found either in the same heads as the pistillidia, or in distinct heads on the same individuals (monoecious), or on separate individuals (dioe- cious). The antheridium (Fig. 1307) is merely a cylindrical or club-shaped sac, composed of a single layer of cells, united to form a delicate membrane ; within which are developed vast numbers of minute, very delicate cells, completely filling the sac. The sac bursting at its apex when mature, the delicate vesicles are discharged. Each of these contains a slender filament, thick- ened at one end and tapering off to a fine point at the other : it may be seen through the transparent walls, spirally coiled up in the interior of each vesicle. When these vesicles are extruded in water under the microscope, the contained filaments may be seen to execute lively movements, wheeling round and round in the vesicle, or, when dis- engaged from the latter, and assuming a corkscrew form, at the same time advancing forward, the thin end of the filament almost always preceding. Minute observation, which is very difficult, both from the rapidity of the motion (which, however, is arrested by poisons) and from the great delicacy of the whole structure, shows that the movements arise from two long and extremely delicate cilia, attached to the tapering end of the filament. These are the spermatozoids, or true fertilizing organs. The pistillidia (Fig. 1306), which ap- pear at the same time as the antheridia, and often mixed with them, are flask-shaped bodies (like an ovary in shape), with a long neck (resembling a style), composed of a cellular membrane. The neck is perforated by an open canal, leading to a cavity below, at the base of which a single cell is the germ of the future sporangium or spore- case. Upon this the spermatozoids, or spiral filaments of the an- theridia, act, one or more of them reaching it by finding their way down the canal of the pistillidium. Then this cell commences a special development, divides into two, and proceeds by ordinary cell- multiplication to build up the sporangium or capsule, in which a countless number of minute spores are produced. The spores of Mosses are formed in the same way as pollen-grains, which they much resemble in structure, being single cells with a double coat, of 29 338 REPRODUCTION IN which the inner is the true cell-wall, and the outer a sort of secre- tion from it. In germination, the inner or proper membrane of the spore swells, and protrudes, from any part of its surface favorably situated, a tubular process, which forms partitions as it elongates and branches, giving rise to what has been fancifully named a pro- embryo, or, better, a prothallus, — a rudimentary plantlet very unlike a Moss, but closely resembling a branched Conferva, consisting, as it does, merely of ramified threads, or rows of cells. After a time certain cells of its A'arious branches, taking a special development, produce buds, which are soon covered with a tuft of rudimentary leaves, and grow up into the leafy stems of the perfected plant. Here a single spore — or rather a peculiar transitory plantlet developed from it — gives rise at once to a number of individuals. And in fecundation it is not the spores themselves that are fertilized, but a cell which by its development gives origin to a sj)ore-case, and this to a vast number of spores* 6G3. Fertilization of a Cell of a Prothallus, or peculiar germinating Plantlet, which thereupon develops into a Plant. Tins most extraordi- nary mode of fecundation has recently been discovered in the Ferns and other of the higher Cryptogamous orders. The fructification of F'erns consists of spore-cases alone, which are borne on the back, margins, or some other part of their leaves (Fig. 1287-1294), and are filled with spores resembling those of Mosses. Since Mosses have long been known to have organs answering in function to stamens, as well as those answering to pistils, and since Ferns are regarded as plants of higher rank than Mosses, their antheridia were diligent- ly sought for upon the fructifying plants, but in vain ; and botanists were therefore forced to the unwilling conclusion, that the highest organized of Cryptogamous plants were asexual. But antheridia, essentially like those of Mosses, have been at length detected, not upon the mature and fructifying plant, but upon the germinating plantlet. The germination of the spores of Ferns had long since been ob- served. The process begins in the same manner as in Mosses ; but the extremity of the tubular prolongation of the spore, converted by partitions into a row of cells, is developed into an expanded, leaf- like body (the pro-embryo, or prothallus as it is now called), which * The fullest account is by Hofmeister, Vergleichende Untersuchungcn der Keimung, Entfaltung, und Fruchtbildung Hoherer Kryptogamen, etc. — Leipsic, 1851. CRYFTOGAMOUS OR FLOWERLESS PLANTS. 339 on a small scale resembles a frondose liverwort. Upon this body, Niigeli, in 1844, found moving spiral filaments, like tbose of the an- theridia of Mosses, &c. This, as Henfrey remarks, " seemed to destroy all grounds for the assumption of distinct sexes, not only in the Ferns, but in the other Crypt ogamia ; for it Avas argued that the existence of these cellular organs producing moving spiral filaments (the so-called spermatozoa) upon the germinating fronds, proved that they were not to be regarded as in any way connected with the reproductive processes. But an essay published by the Count Suminski in 1848 totally changed the face of the question." On the under side of the delicate, Marchantia-like, germinating frond, Suminski found a number of cellular organs of two distinct kinds, answering to antheridia and pistillidia. The former, which are the more numerous, are cells elevated on the surface of the germinating frond, in the cavity of which are formed other cells, filled with minute vesicles containing each a spiral filament coiled up in its in- terior. The organ bursts at its summit, and discharges the vesicles in a mucilaginous mass ; the spiral filaments moving within the vesicles at length make their way out of them and swim about in the water. These filaments, or spermatozoids, resemble those of Mosses, but are flat and ribbon-like, as in Chara, and possess accord- ing to Suminski about six, according to Thuret numerous cilia, by whose vibrations they are moved. The pistillidia, if they may be so called, are rounded cavities in the cellular tissue of the same body, opening on the under side, in the bottom of which is a single glob- ular cell, from which the future growth proceeds. One or more of the active spermatic filaments, liberated by the bursting of the an- theridia, have been found to enter the open pistillidium, and to come to rest and then wither away in contact with this specialized cell. The latter now develops into a bud, or embryo, as it may perhaps be termed, winch grows in the ordinary way, producing an abbrevi- ated axis, sending roots downward and leaf after leaf upwards ; and so producing the mature Fern.* And, as most Ferns are perennial plants, they produce year after year their fructification (consisting * The English reader is referred to Hcnfrey's Translation of Mohl's Anatomy and Pliysiolor/y of the Vegetable Cell ; and Henfrey's Report on the Reproduction and supposed Existence of Sexual Organs in the higher Crijptogamous Plants, in the Report of the BritislT Association for the Advancement of Science, for 1851, reprinted in Silliman's Journal, Vol. 14 and 15 ; from which the above account has been condensed. 340 SPECIAL DIRECTIONS AND merely of spores in spore-cases), without any known limit, and with- out any other fecundation than that which occurred at first upon the germinating plantlet. 664. In Ferns, accordingly, it is not the sporangium that is fer- tilized, still less the spores, but a cell of a peculiar transitory plant- let formed by the germination of a spore. This cell otherwise will not develop at all ; but when thus fecundated, it develops like a bud, and grows into a plant of indefinite longevity, capable of fructifying by a true parthenogenesis (571) throughout its long existence. This is also known to be the case with Equisetaceaa ; and the Lycopodia- ceae or Club-Mosses and other vascular Cryptogamous Plants are thought to have analogous fecundation, although the details as yet are not well made out. CHAPTER XIII. OF THE SPONTANEOUS MOVEJMENTS AND VITALITY OF PLANTS. 665. The facts brought to view in the preceding chapter, namely, that either the spores or the fertilizing corpuscles or filaments of most Cryptogamous plants of every order are temporarily endowed with motivity, naturally raises the inquiry whether such phenomena are altogether exceptional in the vegetable kingdom, or whether the power of executing movements is not a general endowment of plants as well as of animals, although in lesser degree. As we pass in re- view the various phenomena exhibited Jby plants in this respect, and at the same time consider that self-caused motion, internal or exter- nal, or the faculty of directing motion, is a necessary concomitant of life, we shall probably arrive at the conclusion, that this surprising activity of the microscopic spores and spennatozoids of Cryptogamous plants is not altogether anomalous, — that these are merely more vivid manifestations of a power which they share with ordinary vege- tables, — that plants are endowed with life no less really than ani- mals, — that the distinction between plants and the lower animals in this respect is one of degree rather than of kind, — and that it is a characteristic of living things to move. SPONTANEOUS MOVEMENTS IN PLANTS. 341 666. The Special Directions which the parts of all plants assume are the result of self-caused movements, although such movements are mostly much too slow to be directly observed. Among these the most universal are the descent of the root in germination, the ascent of the stem into the light and air, and the turning of branches and the upper surface of leaves towards the light (120, 131, 294). These directions evidently are not the result of mere growth. It is not that the root grows downwards and the stem upwards ; but the root end of the elongating radicle bends or curves in the course of its growth so as to point downwards if not already in that position, and the other extremity, with the plumule, curves upwards, and the young stem, after reaching the light, if unequally illuminated, bends towards the stronger light. 667. Strenuous attempts have been made to explain these changes of direction upon mechanical principles. Mr. Knight thought that the descent of the root and the ascent of the stem were caused by gravitation ; and he seemed to show tliis by his celebrated experi- ments of removing germinating seeds from the influence of gravita- tion, and causing the root and stem to take a different direction in obedience to a different force. He fixed some beans ready to ger- minate in a quantity of moss upon the circumference of a wheel, and made it to revolve vertically at a rapid rate ; replacing the effect of gravity by centrifugal force. On examination, after some days, the young root was found to have turned towards the circumference, and the stem towards the centre of the wheel. The same result took place when the wheel was made to revolve horizontally with con- siderable rapidity ; but when the velocity was moderate, the roots were directed obliquely downwards and outwards, and the stems obliquely upwards and inwards, in obedience both to the centrifugal force and the power of gravitation, acting at right angles to each other. It remained for Mr. Knight to explain how the same force, gravitation, could produce such opposite effects, causing the stem to ascend as well as the root to descend. This he ingeniously at- tributed to their different mode of growth. The root growing at its extremity only, he supposed that the soft substance of the growing point would be acted upon by gravity like an imperfect solid, and accumulated on the lower side ; while the stem, growing by the elongation of an internode or a series of internodes already formed, its solid tissues would be unaffected by gravity, which could affect only its nutritive juices, causing their accumulation on the lower side of a 29* 342 SPECIAL DIRECTIONS AND stem out of the perpendicular line ; which side, thus more actively nourished, would grow more vigorously than the upper, and so cause the stem to turn upwards. To show how baseless this ingenious hypothesis is, we have only to remember, on the one hand, that the fluid contents of the cells of plants arrange themselves in obedience to other forces than gravity, and freely rise against its influence to the summit of the loftiest trees, so that gravity could establish no difference within the diameter of a germinating stem ; and on the other, that the root in germination, if fixed upon its surface, will pen- etrate a fluid of greater weight than itself, such as mercury. More- over, Schultz and Mohl have shown that, by careful management in reversing the ordinary conditions, — as by germinating seeds in damp moss, so arranged that the only light they could receive was reflected from a mirror, which threw the solar rays upon them directly from below, — the ordinary direction of the organs could be reversed, the roots turning upwards into the dark and damp moss, and the stems downAvard into the light. This would prove that light has more effect than gravitation, or any other imaginable influence of the mass of the earth. Yet, — what shows that there is some real relation between the direction assumed by the plant and the earth, — stems which grow in complete darkness always point to the zenith, as is seen in the shoots of vegetables in perfectly dark cellars, and in the elongated, constantly upright stemlet of germinating seeds too deeply buried to receive any light before they reach the surface of the soil. 668. The influence of a mass in some way analogous to attrac- tion is also observed in the germination of the Mistletoe. Its form- ing root turns regularly to the trunk or branch upon which it is parasitic, just as those of ordinary plants turn to the earth. And that it is the mass and not the quality of the body which determines the direction, is seen when germinating seeds of the Mistletoe are fixed close to the surface of a cannon-ball : all the roots as they grow point to its centre and advance to its surface, just as they do to the branch of a tree which they penetrate. 669. When the stem has emerged from the earth into the light of day, this exerts a controlling influence over its direction. Young and green stems always tend to expose themselves as much as possi- ble to the light, and bend, very promptly when delicate, towards the most illuminated side, as is well observed when plants are raised in an apartment lighted from a single aperture : and consequently in the open air, being equally illuminated on all sides, they grow up- SPONTANEOUS MOVEMENTS IN PLANTS. 343 right. De Candolle attempted a mechanical explanation of this bending of green stems towards the light, connecting it with assimi- lation and growth. He supposed that, as the side upon which the light strikes will fix most carbon by the decomposition of carbonic acid (34G - 348), so its tissue will solidify faster, and therefore elon- gate less, than the shaded side (which will become drawn, as the gardener terms it) ; and the stem or branch will necessarily bend towards the shorter or illuminated side. But when the light is equally diffused around a plant, the decomposition of carbonic acid will take place uniformly on all sides, and the perpendicular direc- tion naturally be maintained. Two facts at once demolish this in- genious theory. 1. It is now well known that, under the solar spectrum, the decomposition of carbonic acid in the green parts of plants is effected chiefly by the most luminous rays, that is, by yellow light, and next to this by orange and red ; whereas the bending is strongest under the violet and blue rays, the yellow producing little curvature, and the red none at all. 2. When a stem curved under the light is split from the apex downwards, so as to separate the illuminated from the shaded side, the former curves more than be- fore, while the latter tends to straighten, — showing that it was pulled over by the contraction of the concave side, and not pushed over by its own greater growth. From all this it clearly appears that the turning of parts towards the light, and the other special directions of plants, are independent of growth, and apparently are effected by some inherent power. At least, they have thus far proved no more susceptible of mechanical explanation than the more marked movements of animals. 670. In leaves it is the denser and deeper green upper surface (262) that is presented to the light, while the paler lower surface, of looser tissue, avoids it. The recovery of the natural position, when the leaf is artificially reversed, is the more promptly effected in pro- portion to the difference in structure and hue between the two strata. This movement is so prompt in some plants, that their leaves follow the daily course of the sun. The leaf is more capable of executing such movements, on account of its extended surface, and its pliancy, and aho on account of its usual attachment by an articulation. Here the slender vascular bundles oppose little resistance to lateral motion, while the soft and usually cellular enlargement favors it. Indeed, the efficient cause of the movement appears to be exerted here, and to be connected with the unequal tension or turgescence of 344 SPECIAL DIRECTIONS AND the cells on the two sides. "We might therefore expect more prompt and obvious changes of position in leaves than in stems. Familiar examples of the kind are met with in the altered nocturnal position of the leaves, &c. of many plants (often drooping, or folded as if in repose), which Linnaeus designated by the fanciful name of 671. The Sleep of Plants. This is Avell seen in the foliage of the Locust and of most Leguminous plants, and in those of Oxalis, or Wood-Sorrel. It is most striking hi the leaflets of compound leaves. The nocturnal position is various in different species, but uniform in the same species, showing that the phenomenon is not mechanical. Nor is it a passive state, for, instead of drooping, as do those of the common Locust-tree, the leaflets are very commonly turned upwards, as those of Honey-Locust, or upwards and forwards, as in the Sensi- tive-Plant, contrary to the position into which they would fall from their own weight. De Candolle found that most plants could be made to acknowledge an artificial day and night, by keeping them in darkness during the day, and by illuminating artificially at night. The sensibility to light appeal's to reside in the petiole, and not in the blade of the leaf or leaflet ; for these movements are similarly executed, when nearly the whole surface of the latter is cut away. 672. The leaves of the blossom also assume various positions, according to the intensity and duration of the light. Many expand their blossoms in the morning and close them towards evening, never to be opened again, as those of Cistus, Portulaca, and Spider- wort ; while others, like the Crocus, close when the sun is with- drawn, but expand again the following morning. On the other hand, the Evening Primrose, Silene noctiflora, &c. unfold their petals at twilight, and close at sunrise. The White Water-Lily (Nymphaea) expands in the full light of day, but uniformly closes near the mid- dle of the afternoon, and is then usually withdrawn beneath the sur- face of the Avater. The Morning-Glory opens at the dawn ; the Lettuce, and most Cichoraceous plants, a few hours later, but close under the noonday sun ; the Mirabilis is called Four-o'clock, because opening nearly at that hour in the afternoon, and it closes the next morning ; and so of other species, — each having its own hour or amount of light in which its blossoms open or close. Berthelot men- tions an Acacia at Teneriffe, whose leaflets regularly close at sunset and unfold at sunrise, while its flowers close at sunrise and unfold at sunset. Although these movements, both in leaves and blossoms, are undoubtedly dependent on the light, they are by no means directly SPONTANEOUS MOVEMENTS IN PLANTS. 345 governed by it. The so-called sleep of the common Sensitive Plant, for instance, begins just before sunset, but its waking frequently pre- cedes the dawn of day ; showing that it is not the mere amount of the light which governs the position, in the manner of a mechanical power.* 673. Sensible Movements from Irritation. All the changes of posi- tion already described — like those of the hands of a clock or of the shadow on a dial — are too slow for the motion to be directly seen. But a greater exaltation apparently of this common faculty is observed in the leaflets of various Leguminous plants, especially of the Mimosa tribe, which, when roughly touched, assume their peculiar nocturnal position, or one like it, by a visible and sometimes a rapid movement. The Sensitive Plant of the gardens (Mimosa pudica) is a familiar instance of the kind, suddenly changing the position of its leaflets on being touched or jarred, and applying them one over the other close upon the secondary petiole ; if more strongly irritated, the secondary petioles also bend forward and approach each other, and the general petiole itself sinks by a bend- ing at the articulation with the stem. Similar although less vivid irritability is shown by the Mimosa strigillosa and the Sehrankia of the Southern States, where the leaflets promptly fold up when brushed with the hand. The most remarkable instance of the kind, however, is presented by another native plant of the United States, the Diona?a muscipula, or Venus's Fly-trap (Fig. 297, 298) ; in which the touch even of an insect, alighting upon the upper surface of the outspread lamina, causes its sides to close suddenly, the strong bristles of the marginal fringe crossing each other like the teeth of a steel-trap, and the two surfaces pressing together with considerable force, so as to retain, if not to destroy, the intruder, Avhose struggles only increase the pressure which this animated trap exerts. This most extraordinary plant abounds in the damp, sandy savannas in the neighborhood of Cape Fear Elver, from Wilmington to Fayette- * The odors of flowers, also, are sometimes given off continually, as in the Orange and the Violet, or flowers may nearly lose their fragrance during the heat of mid-day, as in most cases ; while others, such as Pelargonium triste, Hesperia tristis, and most dingy flowers, which are almost scentless during the day, ex- hale a powerful fragrance at night. The night-flowering Cereus grandiflorus emits its powerful fragrance at intervals ; sudden emanations of odor being given off about every quarter of an hour, during the brief period of the expan- sion of the flower. 346 SPONTANEOUS MOVEMENTS IN PLANTS. ville, North Carolina, where it is exceedingly abundant ; but it is not elsewhere found. 674. A familiar, although less striking, instance of the same kind is seen in the stamens of the common Barberry, which are so excit- able, that the filament approaches the pistil with a sudden jerk, when touched with a point, or brushed by an insect, near the base on the inner side. The object of this motion seems plainly to be the dis- lodgement of the pollen from the cells of the anther, and its projec- tion upon the stigma. But in the Dionrea it is difficult to conceive what end is subserved by the capture of insects. In a species of Stylidium of New Holland, not uncommon in conservatories, the column, consisting of the united stamens and styles, is bent over to one side of the corolla ; but if slightly irritated, it instantly springs over to the opposite side of the flower. These are among the more remarkable cases of the kind, but by no means the only ones. Anatomical investigation brings to view no peculiarity in the struc- ture of such plants which might explain these movements. Some other movements, which have been likened to these, are entirely mechanical ; as that of the stamens of Kalmia, where the ten an- thers are in the bud received into as many pouches of the mono- petalous corolla, and are carried outwards and downwards when the corolla expands. In this way the slender filaments are strongly re- curved, like so many springs ; until at length, when the anthers are liberated by the full expansion of the corolla, or by the touch of a large insect or other extraneous body, they fly upwards elastically, projecting a mass of pollen in the direction of the stigma. 675. The twining of stems round a support, and the coiling of tendrils, are attributed by Mold to a dull irritability ; and this is the most plausible explanation that has been offered. The inner side, which becomes concave and has smaller cells, is in this, as in other cases, the irritable portion. "When a foreign body is reached, a contraction of this side causes the tendril partially to embrace the support : this brings the portion just above into contact with it, which is in like manner incited to curve ; and so the hold is secured, or the twining stem continues to wind around the support. In ten- drils this irritability, propagated downward along the concave side, would appear to cause its contraction, which throws the whole into a spiral coil, or, when fixed at both ends, into two opposite spiral coils, thus approximating the growing stem to the supporting body. SPONTANEOUS MOVEMENTS IN PLANTS. 347 676. In all these cases, whether of slow or rapid change of posi- tion, the immediate cause of the movement, however incited, must he either the shortening of the cells on the concave side, or their elongation on the convex side. The fact that stems curved towards the light tend to curve still more when the convex side is cut away (669) points to a contraction of the cells on the concave side as the cause of the curvature. The elastically bursting pods of the Balsam or Touch-me-not (Impatiens), &c. confirm this view. Here the valves of the capsule curve inwards very strongly when liber- ated in dehiscence ; and that this is owing to the shortening of the cells of the inner layer, and not to the enlargement or turgescence of those of the thick outer layer, is readily shown by gently paring away the whole outer portion before dehiscence ; for the inner layer when liberated still incurves and rolls itself up as strongly as before. The short valves at the summit of the pod of Echinocystis slowly curve outwards in dehiscence ; here the cells of the outer layer of the valve are longer and narrower than those of the inner, and the latter are stretched and torn in opening ; so that here the con- traction of the cells on the side which becomes concave is undoubt- edly the cause of the movement. And since muscular movements are effected by the contraction of the cells which, placed end to end, compose a muscular fibril, Ave may suspect that vital movements generally, both in vegetables and in animals, are so far analogous, that they are brought about in the same general way, viz. by the shortening of cells. Even the opening and closing of the stomata of the leaves (268) appear to be controlled by the vital force, and to be effected by a self-caused change in the form of the guardian cells. How the light, or external irritation, or any other influence, acts in inciting this change of form of the cells of some part of a plant, we know no more, and no less, than we know how a nerve, or an electrical current, acts upon a muscle of an animal to bring about the contraction or change of shape of its component cells. If animals make 677. Spontaneous or Automatic Movements, so also do some plants execute brisk and repeated movements irrespective of extraneous force, or even of extraneous excitation, and which, indeed, are ar- rested by the touch. An instance of such spontaneous and contin- ued motion, of the most remarkable kind, is furnished by the trifoli- olate leaves of Desmodium gyrans, an East-Indian Leguminous plant. The terminal leaflet does not move, except to change from the 348 SPONTANEOUS MOVEMENTS IN PLANTS. diurnal to the nocturnal position, and the contrary ; but the lateral ones are continually rising and falling, both day and night, by a suc- cession of little jerks, like the second-hand of a time-keeper ; the one rising Avhile the other falls. Exposure to cold, or cold water poured upon the plant, stops the motion, which is immediately re- newed by warmth. The late Dr. Baldwin is said by Nuttall to have Avitnessed the same thing in our oavii Desmodium cuspidatum, in Georgia ; but the obseiwation has never been confirmed. In several tropical Orchideous plants, and especially in a species of Megaclinium, the loAver petal, or labellum, executes similar spontane- ous moA'ements, A\ r ith great freedom and pertinacity. Such phenom- ena, occurring as they do in Phamogamous plants of ordinary struc- ture may serve to render more credible the true vegetable character of the G78. Free Movements of the SporCS of Algae, and the cor- puscles or spiral filaments of the antheridia of most Cryp- togamous plants, already re- ferred to (G59 - G63). The spores of most of the lower Algas are noAV knoAvn to ex- hibit this peculiar activity at the time of their discharge from the parent cell, when, for some moments, or usual- i ^ 'I'// ly for several hours, they behave like mfusory ani- mals, executing spontaneous moA-ements in the water, until they are about to ger- minate. This singular move- ment Avas first detected many years ago in Vaucheria FIG. 636. Fruiting end of a plant of A'aucheria geminata (after Thuret) ; one of the branches still containing its spore. 637. Moving spore just escaped from the apex of the other branch ; the ciliary apparatus seen oyer the whole surface. 638. Spore in germination. FIG. 639-642. Successive steps in the germination of (Edogoniuin (Conferva) vesicata. 643. The plant developed into a series of cells, four of which display the successive steps in the formation of a spore. 644. The locomotive spore with its vibratile cilia (copied from Thuret). AVhen the movement ceases, and it begins to germinate, it appears as in 639. (The antheridia or fertilizing apparatus of these plants were not known when these figures were made.) SPONTANEOUS MOVEMENTS IN PLANTS. 349 (Fig. 89, G36). Immediately on its discharge from the mother plant the spore begins to move freely in the "water, and continues to do so for some hours, when it fixes itself and begins to grow (Fig. 638). Its movements, moreover, like those of the antheridial fila- ments or corpuscles, may be enfeebled or arrested by the application of a weak solution of opium or chloroform. Through these means it has been ascertained that they are caused by the vibrations of minute cilia which cover the surface, which are rendered visible by thus enfeebling their movement, and which exhibit the closest resemblance to the vibratile cilia of animals, especially those of the polygastric animalcules. In the Conferva tribe generally the vibra- tile cilia occupy one end of the spore, and are in some cases numer- ous (as in Fig. 644), in others only two or three in number. The spores are small, and of about the same specific gravity as the water in which they live, so that a slight force suffices to propel them. 679. Locomotion of Adult Microscopic Plants. The spores of Vau- cheria and the like, becoming quiescent before germination, grow into fixed thread-like plants of considerable size, endowed with no greater degree of motivity than ordinary vegetables. A multitude of still simpler Algre, however, swarm in every pool or stream, so minute in size as to be individually totally invisible to the naked eye (most of them when full grown are very much smaller than the spores of Vaucheria, &c.) ; and these are endowed, even at maturity, with such powers of locomotion that their vegetable character, although now well made out, was long in question on this account alone. Of this kind are the various species of Oscillaria (Fig. 84), so named from the writhing movement they exhibit, the Desmidi- acere, to which Closterium (Fig. 631) belongs, and the nearly allied Diatomacea?, — the lowest, minutest, and the most freely moving of plants, but clearly members of the vegetable kingdom notwithstanding. These execute free movements of translation, in some cases slow, in others rapid ; but the mechanism of the motion is still unknown. 680. Not only, therefore, do plants generally manifest impressi- bility or sensitiveness to external agents, and execute more or less decided, though slow, movements ; but many species of the higher grades exhibit certain vivid motions, either spontaneous or in conse- quence of extraneous irritation ; while the lowest tribes of aquatic plants, as they diminish in size and in complexity of organization, habitually execute, at some period at least, varied spontaneous move- 30 350 SPONTANEOUS MOVEMENTS IN PLANTS. merits, which we are unable to distinguish in character from those of the lowest animals. It is at their lowest confines, accordingly, that the vegetable and the animal kingdoms approach or meet, and even seem to blend their characters. G81. When Ave consider that the excitability of sensitive plants is often transmitted, as if by a sort of sympathy, from one part to another ; that it is soon exhausted by repeated excitation (as is certainly the case in Dionoea, the Sensitive-Plant, &c), to be re- newed only after a period of repose ; that all plants require a season of repose ; that they consume their products and evolve heat under special circumstances with the same results as in the animal kingdom (Chap. VII.) ; that, as if by a kind of instinct, the various organs of the vegetable assume the positions or the directions most favorable to the proper exercise of their functions and the supply of their wants, to this end surmounting intervening obstacles ; when we consider in this connection the still more striking cases of spon- taneous motion that the lower Alga; exhibit ; and that all these motions are arrested by narcotics, or other poisons, — the narcotic and acrid poisons even producing etfects upon vegetables respectively analogous to their different effects upon the animal economy ; we cannot avoid attributing to plants a vitality and a power of " making movements tending to a determinate end," not different in nature, perhaps, from those of the lowest animals. Probably life is essen- tially the same in the two kingdoms ; and to vegetable life faculties are superadded in the lower animals, some of which are here and there not indistinctly foreshadowed in plants. 682. The essential differences between plants and animals were enumerated at the commencement of this work (1G), and have been illustrated in its progress. Distinct as are the general structure and the offices of the two great kinds of organized beings, it is still doubtful whether the discrimination is absolute, or whether the functions of the vegetable and the animal may not, in some micro- scopic organisms, be imposed upon the same individual. PART II. SYSTEMATIC BOTANY. 683. In the preceding chapters plants have been considered in view of their structure and action. And when different plants have been referred to and their diversities noticed, it has been in eluci- dation of their morphology, — of the exuberantly varied forms or modifications under which the simple common plan of vegetation is worked out, as it were, in rich detail. The vegetable kingdom, that is, vegetation taken as a great whole, presents to our view an im- mense number of different kinds of plants, more or less resembling each other, more or less nearly related to each other. It is the object of Systematic Botany to treat of plants as members of a system, or orderly parts of a whole, — and therefore to consider them as to their kinds, marked by differences and resemblances, and to contemplate the relations which the kinds, or individual members of the great whole, sustain to each other. To tins end the botanist classifies them, so as to exhibit their relationships, or degrees of resemblance, and expresses these in a systematic arrangement or classification, — designates them by appropriate appellations, and distinguishes them by clear and precise descriptions in scientific lan- guage ; so that not only may the name and place in the system, the known properties, and the whole history of any given plant, be read- ily and surely obtained by the learner, but likewise an interesting view may be obtained of the general scheme or plan of the Cre- ator in the Vegetable World. G84. Our present endeavor will be to explain the general prin- ciples of natural-history classification, and the foundation, or facts in nature, upon which it rests, and then cursorily to show how these are applied to the actual arrangement of the known species of plants. 352 PRINCIPLES OF CLASSIFICATION. CHAPTER I. OF THE PRINCIPLES OF CLASSIFICATION. 685. Plants and animals — the members of the organic king- doms of nature — exist as individuals (13), of definite kinds, each endowed with the characteristic power of producing like individuals and so of continuing the succession. The different sorts (1.) are re- produced true to their essential characteristics from generation to generation ; and (2.) they exhibit unequal and very various degrees of resemblance or of dissimilarity among themselves. These simple propositions lie at the foundation of all classification and system in natural history. Upon the first rests the idea of species ; upon the second that of genera, orders, and all groups higher than species. 686. Individuals. The idea of individuality is derived from man and ordinary animals, and thence naturally extended to vegetables. Individuals are beings, owing their existence and their characteris- tics to similar antecedent beings, and composed of parts which together constitute an independent whole, indivisible except by mu- tilation. Individuality is perfectly exemplified in all the higher and most of the lower animals, which multiply by sexual propagation only, and in which the offspring, or the ovum, early separates from tbe parent ; but it is incompletely realized in those animals of the lower grade which are propagated by buds or offshoots as Avell as by ova, and where the offspring may remain more or less intimately connected with the parent. Still more is this so in plants, which in every grade are or may be propagated by buds or offshoots ; which in vegetation develop an indefinite number of similar parts ; which produce branches like the parent plant, and capable either of continuing to grow in connection with it, or of becoming independent (232). The individual jdant, therefore, is evidently not a simple and true individual in the proper sense of the word, — in the sense that an ordinary animal is. A kind of social or corporate individu- ality in the complex radiated animals often gives a certain limita- tion and shape to the congeries or polypidom, and in many of them even subordinates certain parts to the common whole, assigning to them special functions for the common weal : and this is universally and more strikingly the case with plants, except the very simplest. INDIVIDUALS. 353 So that for practical purposes, and in a loose, general sense, we take the whole plant as an individual, so long as it forms one con- nected mass, and no longer. But in a philosophical view we cannot well regard this congeries as the true vegetable individual. 687. Accordingly many botanists (of whom are Thouars at the beginning of the present century, and Braun * at the present day) regard as the true individual the shoot, or simple axis with its foli- age, &c, whether this be the primary stem with its roots implanted in the soil, or a branch implanted on the stem. This view simpli- fies our conception of a vegetable, but is itself open to all the objec- tions it raises against the individuality of the plant as a whole. For just as the herb, shrub, or tree is divisible into shoots or series of similar axes, so the shoot is divisible into similar component parts, or phytons (163), indefinitely repeated, and which may equally give rise to independent plants. Those philosophical naturalists, there- fore, who find no stable ground in this position, are forced towards one of two opposite extremes. Some, justly viewing sexual repro- duction as of the highest import, are led to regard the whole vege- tative product of a seed as theoretically constituting one individual, whether the successive growths remain united, or whether they form a thousand or a million of vegetables, as may often happen. Ac- cording to this view, all the Weeping-Willow trees of this country are parts of one individual ; and most of our Potato plants must be- long to one multitudinous individual, while others wholly similar, but freshly grown from seed, are each individuals of themselves ; — a view which apparently amounts to an absurdity in terms and in fact. Others, following out the idea mentioned above, and laying the main stress upon simplicity and indivisibility, rather than upon tendency to separation, regard the phyton in ordinary plants, and the cell in those of lowest grade, as on the Avhole best answering, in the vege- table kingdom, to the simple individual in the animal. But this is merely a question of greater or less analogy. For the individual, in the proper sense of the term, is more or less confluent into a vegeta- tive cycle in all plants, and in many of the lower animals, and attains full realization only in the higher grades of organized existence. * See his elaborate treatise, On the Vegetable Individual in its Relation to Species (of which a translation from the German, by C. F. Stone, was published in the American Journal of Science and the Arts, vols. 19 and 20, 1855), for the com- pletest development of this view, and for the history of the subject generally. 30* 354 PRINCIPLES OF CLASSIFICATION. 688. But, whatever it may be which we practically or philosophi- cally regard as the vegetable individual, it is evident that plants as well as animals occur in a continued succession of organisms or beings which stand in the relation of parent and offspring. Each particular sort is a chain, of which the individuals are the links. To this chain, or (as expressed by Linnaeus) this perennial succes- sion of individuals, the natural-historian applies the name of 689. Species (14). Every one knows that the several sorts of plants and animals steadily reproduce themselves, or, in other words, keep up a succession of essentially similar individuals, and under favorable circumstances increase their numbers. Each particular kind of cultivated plant or domesticated animal is represented before our eyes in a mass of individuals, which Ave know from observation to a certain extent, and from necessary inference, have sprung from the same stock. And common observation has led people everywhere to expect that the different sorts will continue true to their kind, or at least to conclude that the different sorts of plants or of animals do not shade off one into another by insensible grada- tions, like the colors of the rainbow, as would have been the case if there were not distinct kinds at the beginning, and if their distinc- tions were not kept up, unmingled, and transmitted essentially un- altered, from generation to generation. So we naturally assume that the Creator established a definite, although a vast, number of types or sorts of plants and animals, and endowed them with the faculty of propagation each after its kind ; and that these have so continued unchanged in all their essential characteristics. Out of these gen- eral observations and conceptions the idea of species must have origi- nated ; from them we deduce its scientific definition. Namely, that the species is, abstractly, the type or original of each sort of plant, or animal, thus represented in time by a perennial succession of like individuals, or, concretely, that it is the sum of such series or con- geries of individuals ; and that all the descendants of the same stock, and of no other, compose one species. And, conversely, as we can never trace back the genealogy far, Ave naturally infer community of origin from fraternal resemblance ; that is, Ave refer to the same species those indiA'iduals which are as much alike as those are Avhich Ave knoAV to have sprung from the same stock.* * We use the word stock advisedly, (and in one of its proper meanings, that of the original or originals of a lineage,) to avoid the assertion or denial of the SPECIES AND VARIETIES. 355 690. Specific identity is not of course inferred from every strongly marked resemblance ; for the resemblance may be only that of genus, and individuals so related are inferred not to have had fi common origin. Nor is it denied on account of every difference ; for individu- als of the same stock may differ considerably ; in fact, no two plants are exactly alike, any more than two men are. Such differences when they become distinctly marked give rise to 691. Varieties. If two seeds from the same pod are sown in dif- ferent soils, and submitted to different conditions as respects heat, light, and moisture, the plants that spring from them will show marks of this different treatment in their appearance. Such differ- ences are continually arising in the natural course of things, and to produce and increase them artificially is one of the objects of culti- vation. Such variations in nature are transient ; the plant often outlasting the cause or outgrowing its influence, or else perishing from the continued and graver operation of the modifying influ- ences. But in the more marked varieties which alone deserve the name, the cause of the deviation is occult and constitutional ; the deviation occurs we know not Avhy, and continues throughout the existence and growth of the herb, shrub, or tree, and consequently through all that proceeds from it by propagation from buds, as by off- sets, layers, cuttings, grafts, &c. In this way choice varieties of Ap- ples, Pears, Potatoes, and the like, are multiplied and perpetuated. 692. Since the progeny inherits or tends to inherit all the char- acters and properties of the parent, constitutional varieties must have a tendency to be reproduced by seed, — a tendency which might often prevail, within certain limits, over that general influence which would remand the variety to the normal state, were it not for the commingling which so commonly occurs in nature, through the cas- ual fertilization of the ovules of one individual by the pollen of other individuals of the same species. By assiduously pursuing the oppo- origin of each species from a single individual or a single pair, — a question which science does not furnish grounds for deciding. It is evidently more simple to assume the single origin, where there is no presumption to the con- trary, as there may be in the case of triceeious or of organically associated plants or animals ; but the contrary supposition does not affect our idea of species, if we suppose the originals to have been as much alike as individuals proceeding from the same parent are, and to have had a common birthplace. The investi- gation of the geographical distribution of plants more and more favors the idea of the dissemination of each species from a centre of its own. 356 PRINCIPLES OP CLASSIFICATION. site course in domesticated plants, that is, by constantly insuring the fertilization of the ovules of a marked variety by the pollen of the same, and by saving seed only from such of the resulting progeny as possess the desired peculiarity in the highest degree, and so on for several generations, it would appear that 693. Races, viz. varieties whose characteristics are transmissible by seed with considerable certainty, may generally be produced. Of this kind are the particular sorts of Indian Corn, Rye, Cabbage, Lettuce, Radishes, &c, and indeed of nearly all our varieties of culti- vated annual and biennial esculent plants, as well as of several per- ennials, many of which have been fixed through centuries of domes- tication. What is now taking place with the Peach in this country may convince us that races may be developed in trees as well as in herbs, and in the same manner ; and that the reason why most of our cultivated races are annuals or biennials is because these can be perpetuated in no other way, and because the desired result is obtainable in fewer years than in shrubs or trees. Although races hardly exist independently of man, he cannot be said to origi- nate their peculiarities, nor is it known how they originate. The sports, as the gardener calls them, appear as it were accidentally in cultivated plants. The cultivator merely selects the most promis- ing sorts for preservation, leaving the others to their fate. By par- ticular care he develops the characteristic feature, and strengthens and fixes, in the manner already explained, the tendency to become hereditary, so securing the transmissibility of the variety as long as he takes sufficient care of it. If not duly cared for, they dwindle and lose their peculiarities, or else perish ; if allowed to mix with normal forms, they revert to the common state of the species. "Were culti- vation to cease, all these valued products of man's care and skill would doubtless speedily disappear ; the greater part, perhaps, would perish outright ; the remainder would revert, in a few generations of spontaneous growth, to the character of the primitive stock. 694. Although man has no power to create the peculiarities of such varieties, he may manage so as not only largely to increase them, but also to combine the peculiarities of widely different varie- ties of a species, and thereby produce novel results. This is effected by Cross-breeding, i. e. by fertilizing the pistil of one variety Avith the pollen of another variety of the same species. In this way most esteemed new varieties of flowers and fruits are originated, which combine the separate excellences of both parents. The cultivator RACES, HYBRIDS, ETC. 357 often proceeds one step farther, in certain cases, and gives rise to a different kind of cross-breeds, viz. 695. Hybrids. These are cross-breeds from different but nearly related species. It is well known that, by proper precautions, the pistil of a flower of one species may often be fertilized by the pollen of another of a similar constitution, and that the plants raised from the seeds so produced combine the characters and properties of both parents. Some kinds, such as Azaleas and Pelargoniums, hy- bridize very readily ; in others hybridism is effected with difficulty between nearly related species. The gardener produces hybrids among most of Ms favorite plants, and variously cross-breeds and mingles them, so as to confuse the limits of many cultivated species. But in nature hybrids rarely occur. Not more than fifty wild kinds are clearly known as of continued or frequent occurrence. Others may perhaps be originated from time to time ; but their existence is transient. For hybrids are generally, if not always, sterile, and therefore incapable of perpetuation by seed. But their ovules may be fertilized by the pollen of either of their parents, when the progeny reverts to that species, probably retaining, however, some traces of the mixture, unless this should be obliterated by successive fertilizations from individuals of the same parent species. It is probable that cross-fertilization between different individuals of the same species is more common than is generally supposed, and that it is one of Nature's means for repressing variation. On the other hand, continued self-fertilization (or breeding in and in) is almost sure to perpetuate, as well as farther to develop, individual peculiari- ties, i. e. those of variety or race. 696. However plants may be modified by art and man's device, the systematic botanist proceeds upon the ground that the distinc- tions between species, whether small or great, are real, and in nature are permanent, — that variation, wide as it may be, is naturally re- stricted within certain limits. And this appears to be true. As dis- tinctions subordinate to species are in nature both indefinite and transitory, these, however important to the cultivator, are of little account with the systematic botanist. 697. Species are the true subjects of classification. And the end and aim of systematic botany is to ascertain and to express their relationship to each other. The whole ground in nature for the classification of species is the obvious fact that species resemble or differ from each other unequally and in extremely various de- 358 PRINCIPLES OF CLASSIFICATION. grees. If this were not so, or if related species differed one from another hy a constant quantity, so that, when arranged according to their resemblances, the first differed from the second about as much as the second from the third, and the third from the fourth, and so on thi-oughout, — then, with all the diversity in the vege- table kingdom there actually is, there could be no natural founda- tion for their classification. The multitude of species would render it necessary to classify them, but the classification would be wholly artificial and arbitrary. The actual constitution of the vegetable kingdom, however, as appears from observation, is, that some species resemble each other very closely indeed, others differ as widely as possible, and between these the most numerous and the most various grades of resemblance or difference are presented, but always with a manifest tendency to compose groups or associations of resembling species, — groups the more numerous and apparently the less defi- nite in proportion to the number and the nearness of the points of resemblance. These various associations the naturalist endeavors to express, as far as is necessary or practicable, by a series of generali- zations, — of which the lower or particular are included in the higher, — based on the more striking, or what he deems the most important (i. e. the most definite or least exceptional) points of re- semblance of several grades. Linnaeus and the naturalists of his day mainly recognized three grades of association, or groups supe- rior to species, viz. the genus, the order, and the class ; and these are still the principal members of classification. Of these 698. Genera (plural of Genus) are the more particular or special groups of related species. They are groups of species which are most alike in all or most respects, — which are constructed, so to say, upon the same particular model, with only circumstantial dif- ferences in the details. They are not necessarily nor generally the lowest definable groups of species, but are the lowest most clearly defoiable groups which the botanist recognizes and accounts worthy to bear the generic name ; for the name of the genus with that of the species added to it is the scientific appellation of the plant or animal. Constituted as the vegetable and animal kingdoms are, the recognition of genera, or groups of kindred species, is as natural an operation of the mind as is the conception of species from the asso- ciation of like individuals. This is because many genera are so strongly marked, or at least appear to be so, as far as ordinary ob- servation extends. Every one knows the Rose genus, composed of GENERA AND ORDERS. 359 the various species of Roses and Sweetbriers ; the Bramble genus, comprising Raspberries, &c, is popularly distinguished to a cer- tain extent ; the Oak genus is distinguished from the Chestnut and the Beech genus, &c. : each is a group of species whose mutual resemblance is greater than that of any one of them to any other plant. The number of species in such a group is immaterial, and in fact is very diverse. A genus may be represented by a single known species, when its peculiarities are equivalent in degree to those which characterize other genera, — a case which often occurs ; although if this were generally so, genus and species would be equivalent terms. If only one species of Oak were known, the Oak genus would have been as explicitly discerned as it is now that the species amount to two hundred ; it would have been equally distin- guished by its acorn and cup from the Chestnut, Beech, Hazel, &c. Familiar illustrations of genera in the animal kingdom are furnished by the Cat kind, to which belong the domestic Cat, the Catamount, the Panther, the Lion, the Tiger, the Leopard, &c. ; and by the Dog kind, which includes with the Dog the different species of Foxes and Wolves, the Jackal, &c. The languages of the most barbarous people show that they have recognized such groups. Naturalists merely give to them a greater degree of precision, and indicate what the points of agreement are. 699. If all such groups were as definite and as conspicuously marked out as those from which illustrations are generally taken, genera might be as natural as species. But unfortunately the pure- ly popular genera are comparatively few, and although often cor- rectly founded by the unscientific, yet they are as frequently wrongly limited, or based upon fanciful resemblances. Popular nomencla- ture, embodying the common ideas of people, merely shows that generic groups are recognizable in a considerable number of cases, but not that the whole vegetable or the whole animal kingdom is divisible into a definite number of such groups of equally or some- what equally related species. Whether this proves to be so or not, and whether genera are actually limited groups throughout, this is not the place to consider. Suffice it to say, that there is a ground in nature for genera, and that the naturalist is obliged to treat them, for systematic purposes, as strictly definite groups of species. While genera represent the closer relationships of species, 700. Orders or Families (as they are interchangeably called in botany) express remoter relationships or more general resemblances. 360 PRINCIPLES OF CLASSIFICATION. They are groups of kindred genera, or rather genera of a higher grade. For example, Oaks, Chestnuts, Beeches, Hazels, and Horn- beams constitute so many genera, which, although quite distinct, have so strong a family likeness, and are so much alike in their general structure and properties, that they are associated into one order or family group (the Oak family) ; while the Birches and the Alders form another order not very different in character, and the Walnuts and Hickories another. So the Pines, Firs or Spruces, Larches, Cedars, &c, obviously related among themselves so much more than they are to any other genera, are members of the Pine family ; the Raspberry, Blackberry, and Strawberry, Avith many others, are as- sociated with the Pose in the Pose family ; and so on. 701. Classes are to orders what these are to genera. They ex- press more extensive, or the most extensive relations of species, each class embracing all those species which are framed upon the same general plan of structure, however differently that plan may be carried out in particulars. Thus all Exogenous or Dicotyledonous plants constitute one class, their stems, their embryo, their leaves, &c. being constructed upon the same general plan in all the species, while Endogenous or Moncotyledonous plants for the same reasons compose another class. 702. The sequence of groups, rising from particular to universal, is Species, Genus, Order, Class ; or, in descending from the univer- sal to the particular, Class, Order, Genus, Species. 703. These are the common framework of all methods of classifi- cation, both in the animal and the vegetable kingdoms. But these do not exhaust our powers of analysis, nor express all the gradations which we may observe in the relationship of species. They merely gather up what are deemed the most essential indications of re- lationship, and express them under three grades superior to species, which always carry with them distinctive names. But a more elab- orate analysis is often requisite, on account of the large number of objects to be arranged, and the various degrees of relationship which may come into view. And these, when needful, are expressed in a series of intermediate groups or divisions, which may or may not require distinctive names. Karnes for them are, however, a ORDERS, CLASSES, AND THEIR SUBDIVISIONS. 361 great convenience, especially for those which are most natural and definite. For some of these intermediate groups may be as dis- tinctly marked as are those which we call genera or orders. 704. The great advantages and proper use of this intermediate grouping are, that it secures all the benefits of complete analysis without undue multiplication of genera and orders, and that, by ex- tending the scale, more grades of relationship may be noted, and the Avhole expressed in our systems in truer perspective. Accordingly, when groups of species below what we take for genera are recog- nized, and found to be so well marked that by a little lowering of the scale they would be received as genera, they are denominated Subgenera. If less definite, Ave term them merely Sections. For example, Pyrus, the Pear genus, embraces Apples, Pears, Crab- apples and the like ; and the Pear itself is the type or normal rep- resentative. From this the Apple and the several species of Crab- apple differ considerably, but not quite enough to warrant generic separation: they are therefore recognized as forming a subgenus, Mains, of the genus Pyrus. Again, the Bramble genus, Rubus, com- prises both Raspberries and Blackberries, which, although distin- guished by everybody, are not so much or so definitely different from each other as Apples and Crab-apples are from Pears ; so they are ranked merely as sections of the Bramble genus. If we were to receive all such particular groups of species as genera, and give them substantive names, as many naturalists are doing, the nicer grada- tions of affinity would be disregarded, while genera would be reck- oned by tens of thousands ; at length half our species would become genera with substantive names, and the whole advantage of classifi- cation and nomenclature would be lost. The proper discrimination of genera is the real test of a naturalist. 705. When groups intermediate between genera and orders are admitted, they are generally denominated Tribes, and their divis- ions, if any, Subtribes. But the highest divisions of orders, when marked by characters of such importance that it might fairly be questioned whether they ought not to be received as independent orders, take the name of Suborders. For example, the great Rose family, as Ave receiA T e it, embraces three suborders ; one of them represented by the Plum, Peach, Almond, &c. ; a second, by the Pear, Quince, HaAvthorn, and the like ; and the third, by the Rose itself and its immediate relatives. Some botanists receive these three as so many orders : Ave regard them as suborders, be- 31 362 PRINCIPLES OF CLASSIFICATION. cause of the strong family likeness which pervades the whole, and of the transitions between them. In the larger of these suborders, or the proper Rose family, we recognize three tribes : one repre- sented by the Rose genus itself; one by the Bramble genus, with the Strawberry, Cinquefoil, Avens, &c. ; and the third by Spiraea and its near relations. And, again, the second and larger of these embraces genera winch are different enough to be ranked under several subtribes. 706. Upon the same principles, groups may be interposed between the orders and the classes, of which the highest kind will take the name of Subclasses. And even above classes we have the most comprehensive division of all plants into a higher and a lower grade or Series (98) ; which brings us up to the vegetable Kingdom, one of the three great departments of Nature. 707. To exhibit the whole sequence or stages of natural-history classification, so«that the student may see the relative rank of groups, designated by the terms which have now been explained, they are here presented, arranged in a descending series, beginning with the primary division of natural objects into kingdoms, and indicating by small capitals those of fundamental importance and universal use in classification. Kingdoms, Series, Classes, Subclasses, Orders or Families, Suborders, Tribes, Subtribes, Genera, Subgenera, Species, Varieties, Individuals. 708. Characters. An enumeration of the distinguishing marks, or points of difference between one class or order, &c. and the others, is termed its character. Characters accordingly properly embrace only those points which are common to all plants of the group, but not to the other groups of the same rank. The characters of classes, &c. are restricted to those general peculiarities of structure upon which these great groups are established : the ordinal charac- ter recites the particulars in which the plants it comprises differ CHARACTERS. BINOMIAL NOMENCLATURE. 363 from all others of the class ; the generic character enumerates those points which distinguish the plants of the genus in question from all others of the same order or suborder ; the specific character indicates the differences between species of the same genus ; — to which in botanical works more or less of general description, accord- ing to the plan and extent of the work, is generally added. 709. A complete system of Botany will therefore comprise a methodical distribution of plants according to their organization, Avith their characters arranged in proper subordination ; so that the investigation of any one particular species will bring to view, not only its name (which separately considered is of little importance), but also its plan of structure, both in general and in particular, its relationships, essential qualities, and whole natural history. The classification and the method of investigation in natural history con- stitute not only the most complete arrangement known for the col- location of a vast amount of facts, but also the best system of prac- tical logic ; and the study exercises and sharpens at once both the powers of reasoning and of observation, more, probably, than any other pursuit. As a system for collocating facts for convenient ref- erence, a great practical advantage of natural history is secured by its happily devised 710. Binomial Nomenclature. Since the time of Linnams, who in- troduced the system, the scientific name of every plant is expressed by two words, viz. by the name of its species appended to that of its genus, each of a single word. That of the genus, i. e. the ge- neric name, is a substantive ; that of the species, or the specific name, is an adjective adjunct. The same name is never employed for different genera ; the same specific name is not available for more than one species of the same genus, but may be used in any other genus. A few thousand names accordingly serve completely to designate something like 8,000 genera and nearly 100,000 species of plants, in a manner which obviates all confusion, and does not greatly burden the memory. The generic name of a plant answers to the surname of a person, as Brown or Jones ; the specific name answers to the baptismal name, as John or James. Thus, Quercus alba is the botanical appellation of the White Oak ; Quercus being the substantive name for the genus, and alba (white) the adjec- tive name for this particular species ; while the Red Oak is named Quercus rubra ; the Scarlet Oak, Quercus coccinea ; the Live Oak, Quercus virens ; the Bur Oak, Quercus macrocarpa ; and so on. 364 PRINCIPLES OP CLASSIFICATION. The scientific names of plants are all Latin or Latinized ; and that of the species always follows that of the genus. 711. Generic names in botany are derived from various sources. Those of plants known to the ancients generally preserve their clas- sical appellations ; as, for example, Qicercus, Fagus, Corylus, Prunus, Myrtus, Viola, &c. For plants since made known, even their barba- rous names are often adopted, when susceptible of a Latin termina- tion, and not too uncouth ; for example, Thcea and Coffcea, for the Tea and Coffee plants, Patnbusa for the Bamboo, Yucca, Negundo, &c. But more commonly, new generic names, when wanted, have been framed by botanists to express some botanical character, habit, or obvious peculiarity of the plants they designate ; such as Arena- ria, for a plant winch grows in sandy places ; Dentaria, for a plant with toothed roots ; Lunaria, for one with moon-like pods ; Sanguinaria, for the Bloodroot with its sanguine juice ; Crassula, for some plants with remarkably thick leaves. These are instances of Latin derivatives ; but recourse is more commonly had to the Greek language, in which compounds of two words are much more readily made, expressive of peculiarities ; such as Menispermum, or Moonseed ; Lithospermum, for a plant with stony seeds ; Melanthium, for a genus whose flowers turn black or dusky; Epidendrum, for certain Orchideous plants which grow upon trees ; Liriodendron, for a tree which bears lily-shaped flowers, &c. Genera are also dedicated to distinguished persons ; a practice commenced by the ancients ; as Pceonia, which bears the name of Preon, who is said to have employed the plant in medicine ; and Euphorbia, Artemisia, and Asclepias are also examples of the kind. Modern names of this kind are freely given in commemoration of botanists, or of persons who have contributed to the advancement of natural history. Mag- nolia, Bignonia, Lobelia, and Lonicera, dedicated to Magnol, Big- non, Lobel, and Lonicer, are early instances ; Linncea, Tournefortia, Jussicea, HaUeria, and Gronovia, bear the names of the most cel- ebrated botanists of the eighteenth century ; and at the present day almost every devotee of the science is thus commemorated. 712. Specific names are adjuncts, and mostly adjectives, adopted on similar principles. Most of them are expressive of some char- acteristic or obvious trait of the species ; as, Magnolia grandijlora, the Large-flowered Magnolia ; M. macropliylla, the Large-leaved Magnolia ; M. glauca, which has the foliage glaucous or whitened underneath ; or Viola tricolor, from the three-colored corolla of the NATURAL AND ARTIFICIAL SYSTEMS. 365 Pansy ; V. rostrata, a remarkably long-spurred species ; V. rotundi- folia, with rounded leaves ; V. lanceolata, with lanceolate leaves ; V.pedata, with pedately parted leaves ; V. primulcefolia, where the leaves are compared to those of the Primrose ; and V. pubescens, with pubescent or hairy herbage. Sometimes the specific name re- fers to the country which the plant inhabits or was first found in, as Viola Canadensis, the Canadian Violet ; or to the station where it naturally grows, as V. palustris (Marsh Violet). Sometimes it com- memorates the discoverer or describer, when it rightly takes the genitive form, as Viola Muhlenbergii, V. Nuttallii, &c. When com- memorative names are given merely in compliment to a botanist un- connected with the discovery or history of the plant, the adjective form is preferred ; as, Carex Torreyana, C Hookeriana, &c. : but this rule is not universally followed. Specific names are sometimes substantive ; as, Magnolia Umbrella, Ranunculus Flammula, Hypericum Sarothra, Linaria Cymbalaria, &c. (most of these being old generic names used as specific) ; when they do not necessarily accord with the genus in gender. These, as well as all specific names taken from persons or countries, are to be written with a capital initial letter. 713. Varieties may be designated by names when they are re- markable enough to require it. The name of the variety, when used at all, follows that of the species, and is formed on the same plan. Subgenera need to be designated by names, which are sub- stantive, and on the same principle as generic names. These are convenient to refer to, but are not a part of the proper name of a plant, which is that of the genus and species only. 714. The names of genera and species are the same in all botani- cal systems, and therefore are properly alluded to here. But those of orders, and all other groups higher than genera, vary in plan with the system adopted. Classifications are of two sorts, viz. 715. Natural and Artificial Systems. A natural system carries out in practice as perfectly as possible the principles sketched in this chapter, arranging all known species in groups of various grades in view of their whole plan of structure, so placing each genus, tribe, order, &c. next to those it most resembles in all respects. An arti- ficial system arranges the genera by some one character, or set of characters, chosen for convenience, disregarding other considerations. It aims only to provide an easy mode of ascertaining the names of plants, and does not attempt to express their points of resemblance generally, but serves nearly the same purpose as a dictionary. 31* 366 THE PRINCIPLES OF 716. Artificial systems are no longer used in botany, except as keys or helps in referring plants to their proper groups in natural arrangements. But the celebrated Artificial System of Linnaeus so long prevailed, and has exerted so great an influence over the progress of the science, that it is still desirable for the student to understand it. It will therefore be explained, after we have illus- trated the principles of the Natural System of Botany. CHAPTER II. OF THE NATURAL SYSTEM OF BOTANY. 717. The object proposed by the Natural System of Botany is to bi'ing together into groups those plants which most nearly resem- ble each other, not in a single and perhaps relatively unimportant point (as in an artificial classification), but in all essential particu- lars ; and to combine the subordinate groups into successively more comprehensive natural assemblages, so as to embrace the whole vegetable kingdom in a methodical arrangement. All the charac- ters which plants present, that is, all their points of agreement or difference, are employed in the classification ; those which are com- mon to the greatest number of plants being used for the primary grand divisions ; those less comprehensive, for subordinate groups, &c. ; so that the character, or description of each group, when fully given, actually expresses the main particulars in which the plants it embraces agree among themselves, and differ from other groups of the same rank. This complete analysis being carried through the system, from the primary divisions down to the species, it is evident that the study of a single plant of each group Avill give a correct general idea of the structure, habits, and even the sensible proper- ties, of the whole. 718. For it is evident that the relationships of plants are real; that there is not only a general plan of vegetation (with which the student has already become familiar), but also a plan in the relations which subsist between one plant and another ; that the species sustain to each other the relation of parts to a whole, — so that this whole, or vegetable kingdom, is an organized system. And this system, as THE NATURAL SYSTEM OF CLASSIFICATION. 367 far as comprehended, may be to a good degree expressed in our classification. This idea of plan and system in nature supposes a Planner, or a mind which has ordered things so, with intelligence and purpose •, and it is this plan, or its evidences and results, which the naturalist is endeavoring to investigate. The botanist, accordingly, does not undertake to contrive a system, but he strives to express in a classification, as well as he can, the System of Nature, or, in other words, the Plan of the Creator in the Vegetable Kingdom. 719. " So there can be only one natural system of botany, if by the term we mean the plan according to which the vegetable crea- tion was called into being, with all its grades and diversities among the species, as well of past as of the present time. But there may be many natural systems, if Ave mean the attempts of men to inter- pret and express the plan of the vegetable creation, — systems which Avill vary with our advancing knowledge, and with the judg- ment and skill of different botanists, — and which must all be very imperfect. They will all bear the impress of individual minds, and be shaped by the current philosophy of the age. But the endeavor always is to make the classification a reflection of Nature, as far as any system can be which has to express such a vast and ever in- creasing array of facts, and most various and intricate relations, in a series of definite propositions, and have its divisions and subdi- visions following each other in some fixed order." Our so-called natural methods must always fail to give more than an imperfect and considerably distorted reflection, not merely of the plan of the vegetable kingdom, but even of our knowledge of it ; and every form of it yet devised, or likely to be, is more or less artificial, in some of its parts or details. This is inevitable, because, — 720. (1st.) The relationships of any group cannot always be right- ly estimated before all its members are known, and their whole structure understood ; so that the views of botanists are liable to be modified with the discoveries of every year. The discovery of a single plant, or of a point of structure before misunderstood, has sometimes changed materially the position of a considerable group in the system, and minor alterations are continually made by our in- creasing knowledge. (2d.) The groups which we recognize, and dis- tinguish as genera, tribes, orders, &c, are not always, and perhaps not generally, completely circumscribed in nature, as we are obliged to assume them to be in our classification. This might be expected from the nature of the case. For the naturalist's groups, of what- 3G8 THE PRINCIPLES OP ever grade, are not realities, but ideas ; their consideration involves questions, not of things, between which absolute distinctions might be drawn, but of degrees of resemblance, which may be expected to present infinite gradations. (3d.) Although the grades of affinity among species are most various, if not wholly indefinite, the nat- uralist reduces them all to a few, and treats his genera, tribes, &c. as equal units, or as distinguished by characters of about equal value throughout, — which is far from being the case. (4th.) The nat- uralist in his works is obliged to arrange the groups he recognizes in a lineal series ; but each genus, or order, &c. is very often about equally related to three or four others ; so that only a part of the relationship of plants can practically be indicated in the published arrangement. 721. The natural system as sketched by Bernard and A. L. Jus- sieu, and improved by the labors of succeeding botanists, essentially consists of an arrangement of the known genera according to their af- finities under two hundred or more natural orders, and of these under a few great types or classes. What is now most wanted to complete the system is a truly natural arrangement of the orders under the great classes, like that of the genera under their respective orders. Until this is done, the series in which the orders follow one another in botanical works must not be regarded as a part of the system of nature. Different authors adopt different modes of arranging them ; and all of them that a learner could use are avowedly more or less artificial. 722. Omitting all historical details and statements of more or less conflicting views, we will briefly sketch the outlines of the principal divisions of the vegetable kingdom, according to the natural system as we now practically receive it. In explaining the principles of classification, we proceeded from the individual to the class. In ex- amining the actual construction of the system of botany, it is simpler to regard the vegetable kingdom as a Avhole, and show how it is nat- urally divided and subdivided. This is the course a student must follow with an unknown plant before him, which he wishes to refer first to its class, then to its order, and finally to its genus and species. 723. The long and complex series, stretching from the highest organized vegetable down to the simplest and minutest of the Fungi and Algre, is most naturally divided, as we have already seen, into two parts, forming a higher and a lower grade or series (98), viz. THE NATURAL SYSTEM OF CLASSIFICATION. 369 Scries I. Pelenogamous (or Phanerogamous) or Flower- ing Plants (114, 117), which produce flowers and seeds, the latter containing a ready-formed embryo. Series II. Cryptogamous or Flowerless Plants (113, 117, 651), whose organs of reproduction are not flowers, but some more or less analogous apparatus, and which are propagated by spores or specialized cells. 724. "We have next to consider how these two series may be themselves divided, in view of the most general and important points of difference which the plants they comprise exhibit. Whenever Phamogamous plants rise to arborescent forms, a difference in port and aspect at once ax-rests attention ; that which distinguishes our common trees and shrubs from Palms and the like (Fig. 184). On examination, this is found to accompany a well-marked important difference in the structure of the stem or wood, and in its mode of growth. The former present the exogenous, the latter the endoge- nous structure or growth (200-203, 207, &c.). This difference is equally discernible, if not so striking, in the annual or herbaceous stems of these two sorts of Phamoganious plants. A difference is also apparent in their foliage ; the former generally have reticulat- ed, or netted-veined, the latter parallel-veined leaves (276). The leaves of the former usually fall off by an articulation ; those of the latter decay on the stem (309, 310). The Phamogamous series, therefore, divides into two great classes, namely, into Exogenous and Endogenous plants, more briefly named Exogens and Endo- gens. The difference between the two not only pervades their whole port and aspect, but is manifest from the earliest stage, in the plan of the embryo. The embryo of Exogens, as already shown, is provided with a pair of cotyledons (or sometimes with more than one pair) ; that of Endogens, with only one ; whence the former are also termed Dicotyledonous, and the latter Monocotyledo- nous plants (128, 641-643): names introduced by Jussieu, the father of this branch of botany.* Taking these divisions for classes, Ave have * There is, perhaps, no real and complete exception to the coincidence of an exogenous stem with a dicotyledonous (or polycotyledonous) embryo, and of an endogenous stem with a monocotyledonous embryo. Nyctaginaceous plants and some others have a few vascular bundles scattered through their pith, but the rest of the wood is regularly exogenous. The stalk of Podophyllum imi- tates an Endogen, but the subterranean rootstock is truly exogenous, as it should 370 THE PRINCIPLES OF Class I. Exogenous or Dicotyledonous Plants ; those with endogenous stems, netted-veinecl leaves, and dicotyledonous (or rarely polycotyledonous) embryo ; Class II. Endogenous or Monocotyledonous Plants ; those with endogenous stems, mostly parallel-veined leaves, and monocotyledonous embryo. 725. Without entering here into a particular explanation of the diversities of structure which Cryptogamous plants present, suffice it to say that they exhibit three grades of simplification as to their vegetation, which appear to correspond with three different modes of fertilization. Plants of the highest grades of the Cryptogamous series have wood and ducts in their composition (i. e. they are vascu- lar plants, 111), and display the ordinary type of vegetation, viz. with an axis or stem, bearing distinct foliage. But this stem in structure is neither endogenous nor exogenous, and grows from the apex only, having no primary root ; whence these vascular Flower- less plants have been called Acrogens, or Acrogenous plants. Of this kind are Ferns, Lycopodiacea?, Equisetaceoe or Horsetails, &c. These plants, it appears, produce their organs analogous to flowers, and have their fecundation effected, once for all, upon the infantile or germinating plantlet, and the result is the origination of a bud, which develops into the adult plant ; and that bears the fruit, in the form of spore-cases and spores (6G3). Here then are the characters of Class III. Acrogenous Plants ; Cryptogamous plants, with a distinct axis and mostly with foliage, having wood and ducts in their composition : fertilization occurring upon a transient germinat- ing plantlet, and giving rise to the adult plant. 726. The other Cryptogamous plants, being composed of paren- chyma only, (or with slight exceptions,) are' called Cellular plants (111). Among them the Mosses and Liverworts present for the most part the ordinary plan of vegetation ; their organs analogous to flowers appear in the adult plant ; and the fertilization of the pistillidium gives origin to a sporangium in which a multitude of spores, capable of germination, are developed. These compose Class IV. Anophytes : cellular Cryptogamous plants, with distinct stem and foliage, or sometimes these parts confluent into a be. The trunks or rootstocks of Water-Lilies appear to be endogenous ; but those who have investigated them minutely, declare that they are not really so. THE NATURAL SYSTEM OF CLASSIFICATION. 371 frond, composed of parenchyma alone : fertilization giving rise to a sporangium filled with spores. 727. The remaining and lower grade consists of plants such as Lichens, Seaweeds or Alga}, and Fungi, which exhibit no clear dis- tinction into stem, root, and leaves, but consist of single cells or rows of cells in their loAvest grades, and in the higher, of masses of cells disposed in almost every shape, but tending mostly to flat strata or expansions ; hence the vegetation is termed a thallus (or bed), and this word gives a name to the class, viz. Class V. Thallophytes : cellular Cryptogamous plants with no distinction of axis and foliage ; their spores mostly directly fer- tilized (as explained in another place, 656-661). 728. These five classes are unequal in extent and diversity ; the Exogenous class containing much the largest number of orders ; the Endogens also comprising a considerable number ; the others com- prise few orders or main types, but are most of them very rich in tribes, genera, and species. 729. Only the first or highest class presents such marked diver- sity of type among the plants it comprises as to call for the estab- lishment of subclasses, that is, of groups of such importance as to raise the question whether they should not be regarded as classes. This question is raised by the peculiarities of Coniferre (Pines, Cy- presses, the Yew, &c), and by the tropical order of Cycadaceae ; in which, not only are the flowers reduced to the greatest simplicity, but the fertile ones consist of naked ovules merely, borne on the margins or surface of a sort of open leaf, or else of an ovule, without anything answering to a pistil at all. But as these plants are truly exogenous and dicotyledonous (or often polycotyledonous), the better opinion is that they should be ranked under the Exogenous or Dicotyledonous class, as a subclass. So that, while the main body of the first class consists of Subclass I. Angiospermous Exogens : viz. those with proper pistils enclosing their ovules in an ovary, in the ordinary manner ; the pollen to fertilize the ovules received upon a stigma (420, 559, 574), — the others form the Subclass II. Gymnospermous Exogens : those with naked ovules and seeds (as the name denotes), which are fertilized by direct application of the pollen (560, 573, 625). 730. The general plan of the classes and subclasses may be pre- sented in one view, as in the subjoined synopsis. 372 THE NATURAL CLASSES. r/j - S fe eh CM H tH o C 3 15 o Cm ►j P4 O 3 S S3 w DQ a. W X ILLUSTRATIONS OF THE NATURAL ORDERS. 373 731. The arrangement and general character of the principal orders under each class form the subject of the ensuing chapter. Before entering upon it, the 732. Nomenclature of Orders, Tribes, &C. requires some explanation. The names of such groups are in the plural number. As a gen- eral rule, the name of an order is that of some leading or well-known genus in it, prolonged into the adjective termination acecB. Thus, the plants of the order Avhich comprises the Mallow {Malva) are called Malvaceae ; that is, Plantae Malvaceae, or, in English, Malva- ceous plants : those of which the Rose {Rosa) is the well-known representative are Rosaceae, or Rosaceous plants, &c. Some few ordinal names, however, are differently formed, and directly indicate a characteristic feature of the group ; as, for instance, Leguminosce, or the Leguminous plants, such as the Pea, Bean, &c, whose fruit is a legume (610) ; Umbelliferae, or Umbelliferous plants, so named from having the flowers in umbels ; Composite, an order having what were termed compound flowers by the earlier botanists (394) ; Labiate, so called from the labiate or two-lipped corolla which nearly all the species exhibit ; Cruciferae, which have their four petals disposed somewhat in the form of a cross (Fig. 405). 733. Suborders, tribes, and all other groups between orders and genera, bear names framed upon the same principles, that is, they are plural, substantively-taken adjectives, derived from the name of some characteristic genus of the group. Thus the genus Rosa gives name to a particular tribe, Roseae, of the order Rosaceae ; the genus Malva to the tribe Malveae, of the order Malvaceae, &c, — the termination in aceae being avoided, because reserved for ordinal CHAPTER III. ILLUSTRATIONS OF THE NATURAL ORDERS OR FAMILIES. 734. Some authors (such as Jussieu and Endlicher) commence with the lower extremity of the series, and end with the higher ; while others (as De Candolle) pursue the opposite course, beginning with the more perfect Flowering plants, and concluding with the 32 374 ILLUSTRATIONS OF THE NATURAL ORDERS. lowest grade of Flowerless plants. The first mode possesses the theoretical advantage of ascending by successive steps from the simplest to the most complex structure ; the second, the great prac- tical advantage of beginning with the most complete and best under- stood, and proceeding gradually to the most reduced and least known forms, or, in other words, from the easiest to the most dif- ficult ; and is therefore the best plan for the student. 735. Until the orders shall have been successfully associated into natural alliances or superior groups, (of whatever name,) it is most convenient to follow De Candolle's arrangement of them, in a gen- eral way, with such minor alterations as may be called for. The principal Floras now in use are arranged upon this general method. It commences with the Exogenous class, with those orders of it which are generally provided with complete flowers, and which ex- hibit the floral organs in the most normal condition, according to our theory of the blossom (Chap. IX., Sect. I. - III.), that is, which have most of the several parts free and separate. It pro- ceeds to those which are characterized by the union or consolida- tion of their floral organs, and then to those which are reduced or simplified by the suppression or obliteration of parts, ending with the Gymnospermous subclass, the flowers of which are extremely simpli- fied. The Endogenous class succeeds, with a somewhat analogous arrangement, ending Avith Grasses ; and the classes of the Cryp- togamous series follow in the order of their rank. 736. The following cursory sketch takes in the principal orders, freely omitting, however, small and obscure ones, as well as certain well-characterized groups which have no interest to the ordinary student, and no indigenous, naturalized, or commonly cultivated rep- resentatives in the United States. Certain exotic orders are also omitted from the synopsis of the classes or large divisions, for greater simplicity, but are briefly mentioned in their proper place. Fuller accounts of the natural orders, and of their systematic arrangement, structure, properties, &c, must be sought in more extensive works, such as Lindley's Vegetable Kingdom, De Candolle's Prodromus, &c. As applied to the botany of this country, what is essential is comprised in the Manual of the Botany of the Northern United States, by the present writer, and in similar Floras. The characters of the orders, &c. are drawn up in ordinary botanical language. For explanation of the technical terms used, the reader may consult the Glossary at the end of the volume. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 375 Series I. Flowering or Pflenogamous Plants. Plants furnished with flowers (essentially consisting of stamens and pistils), and producing proper seeds. Class I. Exogenous or Dicotyledonous Plants. Stem consisting of a distinct bark and pith, which are separated by an interposed layer of woody fibre and vessels, forming wood in all perennial stems : increase in diameter effected by the annual deposition of new layers between the old wood and the bark, which are arranged in concentric zones and traversed by medullary rays. Leaves commonly articulated with the stems, their veins branching and reticulated. Sepals and petals, when present, more commonly in fives or fours, and very rarely in threes. Embryo with two (or rarely more) cotyledons. Subclass 1. Angiospermous Exogenous Plants. Ovules produced in a closed ovary, and fertilized by the action of pollen through the medium of a stigma. Embryo Avith a pair of op- posite cotyledons. (For convenience, the very numerous orders of this subclass are divided into those with polypetalous, monopetalous, and apetalous flowers. This holds in a general way ; but a good many genera and species of mainly polypetalous, and some of mono- petalous orders, are apetalous. The character of the following divis- ion must therefore be regarded as liable to exception in this respect. For example, many of the genera of the first order have apetalous flowers. — The earlier groups of this division are mostly hypogy- nous ; those that succeed, perigynous ; the last are epigynous.) Division I. Polypetalous Exogenous Plants. Calyx and corolla both present ; and the petals distinct. Conspectus of the Orders. Group 1. Ovaries several or numerous (in a few cases solitary), distinct, when in several rows sometimes cohering in a mass, but not united into a com- pound pistil. Petals and stamens hypogynous. Seeds albuminous. * Stamens or pistils (one or both) numerous or indefinite. Herbs without stipules. Ranunculace^e. Shrubs or trees. Corolla imbricated in the bud. Magnoliace^e. Shrubs or trees. Corolla valvate in the bud. Anonace^;. 376 ILLUSTRATIONS OF THE NATURAL ORDERS. * * Stamens few or definite, mostly before the petals. Pistils one or few. Climbing plants. Dioecious or monoecious. Menispermace^e. Not climbing. Flowers perfect. Anthers opening by valves. Berberidace^e. Group 2. Ovaries several and distinct, or perfectly united into a compound pistil of several cells. Embryo enclosed in a sac at the end of the albu- men, or, in Nelumbium, without albumen. Aquatic herbs. Carpels distinct, immersed in a dilated top-shaped torus. Nelumbiace^:. Carpels united into a several-celled and many-ovuled ovary. NyiiPHiEACEiE. Carpels distinct and free. Stamens 6 - 18. Cabombaceje. Group 3. Ovary compound, 5-celled, with the placenta? in the axis. Sta- mens hypogynous, indefinite. Seeds numerous, anatropous, albuminous, with a small embryo. Marsh herbs, with singular pitcher-shaped or tubular leaves. Sarraceniace^e. Group 4. Ovary compound, with parietal placentae. Petals and sepals 2 or 4, deciduous. Stamens hypogynous. Flower unsymmetrical. Embryo small, in copious albumen, or coiled when there is no albumen. Seeds albuminous : embryo small or minute. Polyandrous : flower regular. Juice milky or colored. Papa ve raceme. Diadelphous or hexandrous : flower irregular. Fumariace.^:. Seeds without albumen : styles and stigmas united into one. Pod two-celled. Radicle folded on the cotyledons. Crucifer^:. Pod one-celled. Embryo rolled up. Capparidaceje. Seeds without albumen : styles or stigmas several. Resedace^e. Group 5. Ovary compound, with parietal placental. Floral envelopes mostly 5-merous ; calyx persistent. Stamens hypogynous. Seeds albuminous. Anthers (5) adnate, introrse, connate. Corolla irregular. Violaceje. Anthers extrorse, or innate, distinct. Corolla regular. Vernation circulate. Petals marcescent. Droserace^e. Vernation straight. Petals usually caducous. Cistace;e. Group 6. Ovary compound, with the placentas parietal, or 2 - 5-celled from their meeting in the axis. Stamens hypogynous. Seeds with a straight embryo and little or no albumen. Sterile filaments or a lobed appendage before each petal. Parnassiace^e. Sterile filaments none : leaves opposite. Stipules none : leaves dotted. Stamens unsymmetrical. Hypericace^. Stipules present : leaves dotless. Stamens symmetrical. Elatinace^e. Group 7. Ovary compound, one-celled with a free central placenta, or 2 - several-celled with the placenta in the axis. Calyx free or nearly so. Stamens hypogynous or perigynous. Embryo peripheric, coiled more or less around the outside of mealy albumen. Petals and stamens numerous. Ovary many-celled. Mesembr y anthem ace^e. Petals 3 - 5 or 6, sometimes wanting. Floral envelopes symmetrical. Stamens 10 or fewer. Caryophyllace^e. Floral envelopes unsymmetrical, or stamens many. Portulacacejj:. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 37.7 Group 8. Ovary compound and several-celled, with the placentas in the axis ; or the numerous carpels more or less coherent with each other or with a central axis. Calyx free from the ovary, with a valvate aestivation. Sta- mens mostly indefinite, monadelphous, or polyadelphous, inserted with the petals into the receptacle or base of the petals. Anthers 1-celled, reniform. Stamens monadelphous. Malvaceae. Anthers 2-celled. Fertile stamens few, monadelphous. Byttneriaceje. Anthers 2-celled. Stamens polyandrous or polyadelphous. Tiliaceje. Group 9. Ovary compound, with two or more cells, and the placenta; in the axis, free from the calyx, which is imbricated in aestivation. Stamens in- definite, or twice as many as the petals, usually monadelphous, hypogy- nous. — Trees or shrubs. Leaves simple, not dotted. Stamens indefinite. Camelliace^e. Leaves pellucid-punctate, mostly compound. Aurantiace^e. Leaves compound, dotless. Stamens 10 or less, monadelphous. Seeds single in each cell, wingless. Meliace^e. Seeds several in each cell, winged. Cedrelace^e. Group 10. Ovary compound, or of several carpels adhering to a central axis, (or rarely distinct in the last two), free from the calyx, which is mostly im- bricated in aestivation. Stamens as many or twice as many as the petals, inserted on the receptacle, often monadelphous at the base. Embryo large. Albumen little or none. Flowers perfect, except in some Rutacece. * Flower irregular and unsymmetrieal. Albumen none. Stamens united over the pistil. Ovules several in each cell. Balsaminace^s. Stamens distinct. Ovules single in each cell. TROPiEOLACEiE. * * Flower regular and mostly symmetrical. Leaves not punctate with transparent dots. Calyx valvate. Albumen none : cotyledons very thick. Limnanthace;e. Calyx imbricated in aestivation. Embryo conduplicate : the radicle bent down on the convolute cotyledons. Geraniaceje. Embryo straight or nearly so. Stamens (fertile) 5. Leaves simple, entire. Linaceje. Stamens 10. Leaves opposite, compound. Zygophyllace.e. Stamens 10. Leaves alternate, mostly compound. Ovules more than one in each cell. Oxaeidace.i;. Ovules only one in each cell. Sijiarubace^k. Leaves punctate with transparent dots. Rutace^c. Group 11. Ovary one, or several and distinct or combined into one, with one or rarely two ovules in each cell. Calyx free ; stamens more or less perigynous, as many or twice as many as the petals. Embryo large : albumen none. Shrubs or trees with a resinous or viscid-milky juice, and mostly polygamous or dioecious flowers. Leaves not punctate. — Intem- perate climates represented only by Anacardiace.e. 32* 378 ILLUSTRATIONS OF THE NATURAL ORDERS. Group 12. Ovary compound, 1 - 5-celled, with one or two ovules erect from the base of the cells. Calyx free or partly adherent. Stamens as many as the petals or sepals and opposite the former. Seeds anatropous, albumi- nous. Woody plants, with a colorless juice. Flowers regular. Leaves alternate. Calyx obscure. Petals valvate, caducous. Embryo minute. Vitaceje. Calyx more conspicuous than the petals, valvate. Rhamnace/e. Group 13. Ovary compound, 2 -5-celled, with only one or two ovules in each cell. Stamens as many as the petals and alternate with them, perigynous. Seeds furnished with an arillus, albuminous, with a large straight embryo. "Woody plants, with regular flowers and simple leaves. — Represented mainly by Celastrace^e. Group 14. Ovary compound and 2-3-celled, with one or two (rarely 3 or 4) ovules in each cell, free from the calyx, which is imbricated in aestivation. Flowers often irregular, and sometimes unsymmetrical. Stamens definite, hypogynous or perigynous. Shrubs, trees, or herbs. Leaves opposite or alternate, not punctate. Stamens distinct, inserted on a hypogynous or perigynous disk. Embryo (except in Staphylea) variously curved or coiled, and destitute of albumen. Sapindace^e. Stamens hypogynous, without a disk. Stamens mostly monadelphous, 10. Flowers regular. Embryo curved ; albumen none. Malpighiace^e. Stamens monadelphous or diadelphous, 6 or 8. Flower irregu- lar and unsymmetrical. Embryo straight in albumen. Polygalace;e. Group 15. Ovary simple and solitary, free from the calyx; the fruit a pod. Flower 5-merous, the odd sepal anterior. Corolla papilionaceous, irregu- lar, or sometimes regular. Stamens monadelphous, diadelphous, or dis- tinct, mostly perigynous. Seeds destitute of albumen Stamens hypogynous, the anterior wanting. Stipules none. Krameriace^e. Stamens mostly perigynous. Fruit a legume. Leguminos.e. Group 16. Ovaries one or several, either simple and distinct, or combined into a compound ovary with two or more cells and the placentae in the axis. Petals and the distinct stamens perigynous. Seeds destitute of albumen. * Calyx free, although often enclosing the ovaries in its tube, except when the latter are united, when it is adnate to the compound ovary, and the sta- mens are indefinite. Leaves alternate, stipulate. Cotyledons plane. Rosaceje. Leaves opposite, not stipulate, nor pellucid-punctate. Calycanthace/E. Leaves opposite, not stipulate, pellucid-punctate. Myrtace.e. * * Calyx free from the compound ovary. Stamens definite. Lythrace^b. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 379 * * * Calyx-tube adnate to the compound ovary. Stamens definite. Anthers opening by a pore at the apex. Melastomace^e. Anthers opening longitudinally. Stipules between the petioles. Leaves opposite. Rhizophorace;e. Stipules none. Calyx valvate. Cotyledons convolute. Fruit indehiscent, 1-celled. Combretace^e. Cotyledons plane. Fruit mostly 2- 4-celled. Onagrace^e. Group 17. Ovary compound, one-celled, with parietal placentas. Petals and (with one exception) stamens inserted on the throat of the calyx. Flowers perfect, except in Papayacete. * Calyx adherent to the ovary. Albumen none or very little. Petals and stamens indefinite. Cactace-s:. Albumen very copious. Embryo minute. Stamens 5. Grossulaceje. Albumen present. Embryo rather large. Stamens indefinite. Loasace-S. * * Calyx free from the ovary. Flowers perfect. Stamens 5. Stamens distinct and perigynous. Turnerace^;. Stamens monadelphous, adnate to the gynophore. Passiflorace^e. Flowers dioecious. Stamens 10, on the corolla. Papayace^e. Group 18. Ovary compound, one - several-celled, the placenta? parietal (either truly or falsely so). Calyx adnate. Corolla frequently monopetalous. Stamens mostly united either by their filaments or anthers. Flowers dioecious or monoecious. Albumen none. Succulent or tender vines with tendrils. Cucurbitace^e. Group 19. Ovaries two or more, many-ovuled, distinct, or partly, sometimes completely, united, when the compound ovary is one-celled with parietal placenta;, or 2 - many-celled with the placentae in the axis. Calyx either free from the ovary or more or less adherent to it. Petals and stamens inserted on the calyx ; the latter mostly definite. Seeds albuminous, nu- merous. Pistils of the same number as the sepals. Crassulace^e. Pistils fewer than the sepals, more or less united. Saxifragace^e. Group 20. Ovary compound, 2- (rarely 3-5-) celled, with a single ovule sus- pended from the apex of each cell. Stamens usually as many as the pet- als or the lobes of the adherent calyx. Embryo small, in hard albumen. * Summit of the (often 2-lobed) ovary free from the calyx ; the petals and sta- mens inserted on the throat of the calyx. Hamamelace^:. * * Calyx-tube entirely adherent to the ovary. Stamens and petals epigynous. Fruit separable into two dry carpels. Flowers umbellate. Umbellifer^:. Fruit drupaceous, usually of more than two carpels. Araliace-e. Fruit a 1 - 2-celled drape. Flowers cymose or capitate. Cornace^;. 380 ILLUSTRATIONS OF THE NATURAL ORDERS. 737. Ord. RannilCUlaceaB {Crowfoot Family). Herbaceous, occa- sionally climbing plants, with an acrid watery juice, and usually palmately or ternately lobed or divided leaves, without stipules. Calyx of three to six, usually five, distinct sepals, deciduous, except in Paeonia and Helleborus. Petals five to fifteen, or often none. Stamens indefi- nite, distinct. Ovaries nu- merous, rarely few or soli- tary, distinct, in fruit becoming achenia (Fig. 566, 567) or follicles (Fig. 579, 648, 649), or in Aetata a berry. Embryo minute, at the base of firm albumen (Fig. 650, 610). — Ex. Ranunculus, the But- tercup (Fig. 645), which has regular flowers with petals. Clematis (Vir- gin's Bower, which is the type of a tribe), Anemone (Fig. 411), Hepatica (Liver-leaf), &c. have no petals, but the calyx is petaloid. In these the flow- ers are regular. The Larkspur (Fig. 398) and Monkshood (Fig. 401) have the flowers irregular, and the Colum- bine (Fig. 646) has petals in the form of spurs. Aetata (Baneberry) and one Larkspur have a solitary ovary : in the latter the petals are consoli- dated. Zanthorhiza (Yellow-root) has only five or ten stamens. — The juice of all Banunculaceous plants is acrid, or even caustic : some, as the Aconite, are virulent narcotico-acrid poisons. 738. Ord. DilleniaceSB, consisting chiefly of tropical and Australian shrubs and trees, probably includes Crossosoma of Nuttall, a singu- lar Californian genus. The order ranks between the preceding and succeeding, but is nearer the former, from which it is known by its arillate seeds. FIG. 645. Vertical section of the flower of a Buttercup. FIG. 646. Flower and part of a leaf of Aquilegia Canadensis (Wild Columbine). 647. A detached petal. 648. The five carpels of the fruit. 649. A separate follicle. 650. Vertical section of the seed, showing the minute embryo. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 381 739. Ord. MagllOliacefE (Magnolia Family). Trees or shrubs; with ample and coriaceous, alternate, entire or lobecl leaves, usually punctate with minute transparent dots : stipules membranaceous, en- veloping the bud, falling off when the leaves expand. Flowers soli- tary, large and showy. Calyx of three deciduous sepals, colored like the petals ; the latter in two or more series of three. Stamens nu- merous, with adnate anthers. Carpels either several in a single row, or numerous and spicate on the prolonged receptacle ; in the latter case usually more or less cohering Avith each other, and form- ing a fruit like a cone or strobile. Seeds mostly one or two in each carpel, sometimes drupaceous and suspended, when the carpels open, by an extensile thread, composed of unrolled spiral vessels. Em- bryo minute, at the base of homogeneous fleshy albumen. There are three well-marked suborders, by many ranked as orders, viz. : — 740. Subord. Magnolieffi (Magnolia Family proper), characterized principally as above, especially by the stipules and the imbricated spiked carpels : — represented by Magnolia and Liriodendron. The bark, &c. is bitter and aromatic, with some acridity. 741. Subord. WilltereSB (Winter 's-Bark Family) has no stipules, and the carpels occupy only a single verticil. These have more FIG. 651. Magnolia glauca. 652. A stamen, seen from the inside, showing the two lobes of the adnate anther. 653. The carpels in fruit, persistent on the receptacle, and opening by the dorsal suture ; the seeds suspended by their extensile cord of spiral vessels. 382 ILLUSTRATIONS OF THE NATURAL ORDERS. pungent and purer aromatic properties ; as in Micium, the Star- Anise, the seeds and pods of which furnish the aromatic oil of this name. 742. Sllbord. SchizandreSB is monoecious or dioecious, with the pis- tils spicate or capitate on a prolonged receptacle ; the stamens often monadelphous. Leaves sometimes toothed, destitute of stipules. — Ex. Schizandra. These are mucilaginous, with little aroma. 743. Ol'd. HIoilillliacecE is a small group, found in the southern hemisphere, with pungent ai'omatic properties, most allied to the last order according to Dr. Hooker (or to Calycanthaceos, according to Tulasne), but chiefly apetalous, and with opposite leaves. 744. Ol'd. AnonaceEB {Custard-Apple Family). Trees or shrubs, with alternate entire leaves, destitute of stipules. Flowers large, but dull-colored. Sepals 3. Petals 6, in two rows, valvate in aesti- vation. Stamens numerous, in many rows, with extrorse anthers. Carpels few, or mostly numerous and closely packed together, some- times cohering and forming a fleshy or pulpy mass in the mature FIG. 654. Flowering branch of the Papaw (Asimina triloba) of the natural size. 655 The receptacle, with all but the pistils removed. 656. A stamen, magnified. 657. A'iew of three baccate pods from the same receptacle (much reduced in size) ; one cut across, another length- wise, to show the large bony seeds. 658. Section of the seed, to show the ruminated albumen. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 383 fruit. Seeds one or more in each carpel, with a hard and brittle testa: embryo minute, at the base of hard, ruminated albumen. The four species of our so-called Papaw (Asimina) are our only rep- resentatives of this chiefly tropical order, which furnishes the lus- cious custard-apples of the East and West Indies, &c. Aromatic properties, with some acridity in the bark, &c., prevail in the order. Monodora yields the calabash-nutmeg. 745. Ord. MjTisticacefC {Nutmeg Family), consisting of a few tropi- cal trees (which bear nutmegs), differs from Anonacea? in havin°* monoecious or dioecious and apetalous flowers, &c. The aril and the albumen of the seeds are fine aromatics. The common nutmeg is the seed of Myristica moschata (a native of the Moluccas) deprived of the testa : mace is the aril of the same species. The ruminated albumen is nearly peculiar to this family and the Anonaceas. 746. Ord. MenispermacetE {Moonseed Family). Climbing or twin- ing shrubby plants, with alternate and simple palmately-veined leaves, destitute of stipules ; and small flowers in racemes or panicles, mostly dioecious, the parts commonly in two or more rows of three or four each. Calyx of three to twelve sepals, in one to three rows, deciduous. Petals as many as the sepals or fewer, small, or some- times wanting in the pistillate flowers. Stamens as many as the petals, and opposite them, or two to four times as many : anthers often four-celled. Carpels usually several, but only one or two of them commonly fructify, at first straight, but during their growth FIG. 659. Staminate flower of Menispermum Canadense. 660. A stamen, with its four- lobed anther. 661. A pistillate flower of the same. 662. A solitary fruit. 663. Two drupes on the same receptacle, cut across ; one through the pulpy exocarp only, the other through the bony endocarp and seed. 664. A drupe divided vertically (the embryo here is turned the wrong way). 665. The seed, and, 666, the coiled embryo detached. 384 ILLUSTRATIONS OF THE NATURAL ORDERS. often curved into a ring ; in fruit becoming berries or drupes. Seeds solitary, filling the cavity of the bony endocarp : embryo large, curved or coiled in the thin fleshy albumen. — Menispermum, or Moonseed (Fig. 413, 414, 659-666), Cocculus. The roots are bitter and tonic (e. g. Colombo Root of the materia medica) ; but the fruit is often narcotic and acrid ; as, for instance, the very poisonous Cocculus Indiciis of the shops, once used for rendering malt liquors more intoxicating, and for stupefying fishes. 747. Ord. BerberidaceSB (Barberry Family). Herbs or shrubs, with a watery juice ; the leaves alternate, compound or divided, usu- ally without stipules. Flowers perfect. Calyx of three to nine sepals, imbricated in one to several rows, often colored. Petals as many as the sepals and in two sets, or twice as many, often with a pore, spur, or glandular appendage at the base. Stamens equal in FIG. 668. A shoot of Berberis vulgaris, the common Barberry. 669. A flowering branch from the axil of one of its leaves or spines, the following year. 670. An expanded flower. 671. A petal, nectariferous near the base. 672. A stamen ; the anther opening by uplifted valves. 673. Cross-section of a young fruit. 674. Vertical section ; the seeds attached at the base. 675. Vertical section of a seed enlarged, showing the large embryo with foliaceous cotyledons and a taper radicle, surrounded by albumen. 676. The embryo separate. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 385 number to the petals and opposite them, or rarely more numerous ; anthers extrorse, the cells commonly opening by an uplifted valve (Fig. 475, G72). Carpel solitary, often gibbous or oblique, forming a one-celled pod or berry in fruit. Seeds sometimes with an aril : embryo (often minute) surrounded with a fleshy or horny albumen. — Ex. The Barberry, the sharp spines of which are transformed leaves ; the Mahonias are Barberries with pinnated leaves. Caulo- phyllum thalictroides, the Blue Cohosh, is remarkable for its eva- nescent jjericarp (559), and the consequent naked seeds, which resemble drupes Podophyllum peltatum (the Mandrake) presents an exception to the ordinal character, having somewhat numerous stamens, with anthers which do not open by valves ; but the latter anomaly is also found in Nandina. The order is remarkable for this valvular dehiscence of the anthers, and for the situation of both the stamens and petals opposite the sepals. But this latter pecu- liarity is easily explained away (4G1). The fruit is innocent or eatable ; the roots, and also the herbage, sometimes drastic or poison- ous, as in Podophyllum. 748. Ol'd. NelumbiacCiE {JSfelumbo Family). Aquatic herbs, with large leaves and flowers, on long stalks arising from a prostrate trunk or rhizoma, which has a somewhat milky juice : the leaves orbicular and centrally peltate. Calyx of four or five sepals, decid- uous. Petals numerous, inserted in several rows into the base of a large and fleshy obconical torus, deciduous. Stamens inserted into the torus in several rows : the filaments petaloid ; the anthers ad- nate and introrse. Carpels several, separately immersed in hollows of the enlarged flat-topped torus or receptacle (Fig. 427), each con- taining a single anatropous ovule ; in fruit forming hard, round nuts. Seed without albumen : embryo very large, with two fleshy cotyle- dons, and a highly developed plumule. — Ex. The order consists of the single genus Nelumbium, embracing two species ; one a native of Asia, the other of North America. They are chiefly remarkable for their large and showy leaves and flowers. The nuts are eatable. It should be regarded rather as a suborder of the next. 749. Ol'd. NymphaiacCfE {Water-Lily Family). Aquatic herbs, with showy flowers and cordate or peltate leaves, arising from a prostrate trunk or rhizoma, and raised on long stalks above the water, or floating on its surface. Calyx and corolla of several or numerous imbricated sepals and petals, which gradually pass into each other ; persistent ; the latter inserted on the fleshy torus which surrounds 33 386 ILLUSTRATIONS OF THE NATURAL ORDERS. or partly encloses and adheres to the pistil ; the inner series gradu- ally changing into stamens. Stamens numerous, in several rows, inserted into the torus with or above the petals ; many of the outer filaments petaloid (Fig. 344), the adnate anthers introrse. Fruit in- dehiscent, pulpy when ripe, many-celled, crowned with the radiate stigmas ; the anatropous seeds covering the spongy dissepiments. Embryo small, enclosed in a membranous bag, which is next the hilum, and half immersed in the mealy albumen. Structure of the trunk appearing rather endogenous than exogenous. — Ex. Nym- phsea, the White Water-Lily ; Nuphar, the Yellow Pond-Lily ; and the magnificent Victoria of tropical South America, the most gigan- tic and showy of aquatics, both as to its flowers and its leaves. Mu- cilaginous plants, with slight astringency ; no important properties. 750. Ord. CabombaccSB {Water-shield Family) is really merely a simplified state of the last, with only one series of sepals and petals, FIG. 677. Open flower, with a flower-bud and leaf of the White Water-Lily (Nymphasa odorata) ; the inner petals passing into stamens. 678. A flower with all the parts around the pistil cut away except one of the petaloid stamens, one intermediate, and one proper stamen. 679. An inner petal, with the imperfect rudiments of an anther at the tip. 680. Transyerse section of an ovary. EXOGENOUS OK DICOTYLEDONOUS PLANTS. 387 definite stamens, or nearly so, with innate anthers, and the gynrcciuni of few apocarpous, free, and few-ovuled pistils ; the ovules chiefly on the dorsal suture. Brasenia and Cabomba are all the genera. 751. Ord. SarmceniaCCiT (Water-Pitcher Family). Perennial herbs, growing in bogs ; the (purplish or yellowish-green) leaves all radical and hollow, pitcher-shaped (Fig. 299, 300), or trumpet-shaped. Calyx of five persistent sepals, with three small bracts at its base. Corolla of five petals. Stamens numerous. Summit of the com- bined styles very large and petaloid, five-angled, covering the five- celled ovai-y, persistent. Fruit five-celled, five-valved, with a large placenta projecting from the axis into the cells. Seeds numerous, albuminous, with a small embryo. — Sarracenia, from which the above character is taken, was the only known genus of the order, until the recent discovery of Heliamphora in Guiana, which is apeta- lous, its scape bearing several flowers ; as does that of a third genus, FIG. 681. Brasenia peltata (Water-shield); the lower flower with the floral envelopes and a part of the stamens removed. 6S2. A magnified stamen. 683. A magnified carpel. 684. The same, divided lengthwise, showing the ovules attached to the outer or dorsal suture ! C85. Sec- tion of a carpel, in fruit. 686. A magnified seed, with half the outer integument removed, displaying at the upper extremity the bag which contains the embryo. 687. A magnified sec- tion through the middle of the albumen, &c. ; bringing to view the minute embryo enclosed in its sac, lying outside of the albumen, which forma the principal bulk of the seed. 388 ILLUSTRATIONS OF THE NATURAL ORDERS. Darlingtonia, Torr., recently discovered in California, Avith calyx and corolla not very unlike those of Sarracenia, but without the umbrella- like style. The species of Sarracenia are all Eastern North Amer- ican. The affinities of the group are unsettled. 752. Ord. PapaveraceOB (Poppy Family). Herbs with a milky or colored juice, and alternate leaves without stipules. Calyx of two (rarely three) caducous sepals. Corolla of four to six regular petals. Stamens eight to twenty-four, or numerous. Fruit one-celled, with two to five or numerous parietal placentae, from which the valves often separate in dehiscence. Seeds numerous, with a minute em- bryo, and copious fleshy and oily albumen. — Ex. The Poppy (Pa- paver), the leading representative of this small but important family, is remarkable for the extension of the placentas so as almost to divide the cavity of the ovary into several cells, and for the dehiscence of the capsule by mere chinks or pores under the edge of the crown FIG. 688. Sanguinaria Canadensis (the Bloodroot). 689 The pod, divided transversely, showing the parietal attachment of the seeds 690 Longitudinal section of a magnified seed with its large rhaphe, showing the minute embryo, near the extremity of the albumen. 691. Flower-bud of Eschscholtzia. 692. The calyptriforni calyx detached from the base. 693. Pod of the same. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 389 formed by the radiate stigmas. Eschscholtzia, now common in gardens, is remarkable for the expanded apex of the peduncle, and for the union of the two sepals into a calyptra, like a candle-extin- guisher, which, separating at the base, is thrown off by the expan- sion of the petals. The colored juice is narcotic and stimulant. That of the Poppy yields Opium. That of the Celandine and of the Bloodroot (Sanguinaria) is acrid. 752'. Ord. FamariaceiC {Fumitory Family). Smooth herbs, Avith brittle stems, and a watery juice, alternate dissected leaves, and no stipules. Flowers irregular. Calyx of two sepals. Corolla of four petals, in pairs ; the two outer, or one of them, spurred or sac-like at the base ; the two inner, callous and cohering at the apex, includ- ing the anthers and stigma. Stamens six, in two parcels opposite the outer petals ; the filaments of each set usually more or less united ; the middle one bearing a two-celled anther ; the lateral, with one-celled anthers. Fruit a one-celled and two-valved pod, or round and indehiscent. Seeds with fleshy albumen and a small embryo. — Ex. Fumaria, Dicentra (Fig. 3G9-374), Corydalis. A small and unimportant tribe of plants, chiefly re- markable for their singular irregular flowers ; by which, with their watery juice, they are distin- guished, and that not very definitely, from the pre- ceding family. 753. Ord. Crncifcra {Mustard Family). Herbs, with a pungent or acrid watery juice, and alternate leaves without stipules ; the flowers in racemes or corymbs, with no bracts to the pedicels. Calyx of four sepals, deciduous. Corolla of four regular petals, with claws, their spreading limbs forming a cross (Fig. 694). Stamens six, two of them short- er {tetradynamous, Fig. 695, 589). Fruit a pod (called a silique when much longer than broad, or a silicle when short, Fig. 703), winch is two-celled by a membranous partition that unites the two marginal placentae, from which the two valves usually fall away. Seeds with no albumen : embryo with the cotyledons folded on the radicle. — Ex. The Water-Cress, Radish, Mustard, Cabbage, &c. A very natural order, perfectly distinguished by having six tetra- dynamous stamens along Avith four petals and four sepals, and by the FIG. 694. Flower of Mustard. 695. The stamens and pistil. 33* 390 ILLUSTRATIONS OF THE NATURAL ORDERS. peculiar pod. The peculiarity of the stamens is explained, and the singular symmetry of the flower illustrated, on p. 243. All these plants have a peculiar volatile acridity (and often an ethe- real oil, which abounds in sulphur) dispersed through every part, from which they derive their peculiar odor and sharp taste, and their stimulant, rubefacient, and antiscorbutic properties. The roots of some perennial species, such as the Horseradish, or the seeds of annual species, as the Mustard, are used as condiments. In some cultivated plants, the acrid principle is dispersed among abundance of saccharine and mucilaginous matter, affording wholesome food ; as the root of the Turnip and Radish, and the leaves and stalks of the Cabbage and Cauliflower. None are really poisonous plants, although some are very acrid. Several species are in FIG. 096. A Cruciferous flower. 697. The same, with the calyx and corolla removed, show- ing the tetradynamous stamens. 698. Siliquts of Arabis Canadensis ; one of them with one of the valves detached, showing the seeds lying on the false partition ; the other valve also falling away. 699. A magnified cross-section of one of the winged seeds, showing the embryo with the radicle applied to the edge of the cotyledons (cotyledons accambent). 700. The embryo detached. 701. The raceme of Draba verna, in fruit. 702. A cross-section of one of the sili- cles, magnified, exhibiting the parietal insertion of the seeds, and the false partition. 703. A silicle of Shepherd's Purse (Capsella Bursa Pastoris). 704. The same, with one of the boat- shaped valves removed, presenting a longitudinal view of the narrow partition, &c. 705. A magnified cross-section of one of the seeds, showing the embryo with the radicle applied to the side of the cotyledon (cotyledons incumbent). EXOGENOUS OK DICOTYLEDONOUS PLANTS. 391 cultivation, for their beauty or fragrance ; such as the Wall-flower, Stock, &e. 754. Ord. Cappai'idaceSG {Caper Family). Herbs, or in tbe tropics often shrubs or trees ; differing from Cruciferae in the one-celled pod (which is often stalked) being destitute of any false partition ; in the kidney-shaped seeds ; and in the stamens, which, when six, are scarcely tetradynarnous, and are often more numerous. — Fx. Cle- ome, Polanisia, Gynandropsis ; chiefly tropical or subtropical. Many have the pungency of Cruciferre, but are more acrid. Capers are the pickled flowei'-buds of Capparis spinosa of the Levant, &c. The roots and herbage or bark are bitter, nauseous, and sometimes poisonous. 710 709 755. Ord. Resedacea) {Mignonette Family). Herbs, with a watery juice, and alternate leaves without stipules, except a pair of glands be so considered : the flowers in terminal racemes, small, and often fragrant. — Calyx persistent, of four to seven sepals, somewhat united at the base. Corolla of two to seven usually unequal and lacerated petals, with broad or thickened claws (Fig. 377). A fleshy disk is commonly present, enlarged posteriorly between the petals and the stamens, and bearing the latter, which vary from three to forty in number, and are not covered by the petals and sepals in the bud. Fruit a one-celled pod, with three to six parietal placenta?, three to six-lobed at the apex, where it opens along the FIG. 706. Flower of Gynandropsis. 707. Flower of Polanisia graveolens. 708. Fructified ovary of the same, a portion cut away by a vertical and horizontal section, to show the single cell and two parietal placentae. 709. Cross-sectioa of the ovary. 710. Section of the seed and embryo. 392 ILLUSTRATIONS OP THE NATURAL ORDERS. inner sutures, usually long before the seeds are ripe. Seeds several or many, curved or kidney-sliaped, •with, no albumen ; the embryo incurved. — Ex. The common representatives of this order are the Mignonette (Reseda odorata), prized for its fragrant flowers, and the Weld (R. Luteola), which yields a poor dye. 75G. Ord. FlaCOUrtiacCfC, a group of tropical shrubs and trees, placed in this vicinity, is best known by Bixa Orellana, which yields Arnatto, the orange-red dried pulp of the pod, surrounding the seeds. 757. Ord. YiolaceSD ( Violet Family). Herbs (in tropical countries sometimes shrubby plants), with mostly alternate simple leaves, on petioles, furnished with stipules; and irregular flowers (Fig. 896, 397). Calyx of five persistent sepals, often auricled at the base. Corolla of five unequal petals, one of them larger than the others and commonly bearing a spur or a sac at the base : aestivation imbri- cative. Stamens five, with short and broad filaments, which are usually elongated beyond the (adnate introrse) anthers ; two of them commonly bearing a gland or a slender appendage which is concealed in the spur of the corolla : the anthers approaching each other, or united in a ring or tube. Style usually turned to one side FIG. 711. Viola sagittata. 712. One of the stamens without appendage, seen from within ; and one furnished with a spur -like appendage on the back. 712 a . A capsule which has opened and separated into three valves ; the calyx still persistent. 712 J . A vertical section of the seed and embryo. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 393 and thickened at the apex. Fruit a one-celled capsule, opening by three valves, each bearing a parietal placenta on its middle. Seeds several or numerous, anatropous, with a crustaceous integument, and a straight embryo, nearly the length of the fleshy albumen (Fig. G04, G05). — Ex. The Violet is the principal genus of this order; some species, like the Pansy, are cultivated for the beauty of their flow- ers ; others, for their delicate fragrance. The roots of all are acrid, and emetic. Those of some South American species of Ionidium furnish a part of the Ipecacuanha of commerce. 758. Ol'tl. CistaceOB {Rock-Rose Family). Low shrubby plants or herbs, with simple and entire leaves (at least the lower opposite). Calyx of five persistent sepals ; the three inner with a convolute aestivation ; the two outer small or sometimes wanting. Corolla of five, or rarely three, regular petals, convolute in aestivation in the direction contrary to that of the sepals, often crumpled, usually ephemeral, sometimes wanting, at least a portion of the flowers. Stamens few or numerous, distinct, with short innate anthers. Fruit a one-celled capsule with parietal placentae, or imperfectly three to five-celled by dissepiments arising from the middle of the valves (dehiscence therefore loculicidal), and bearing the placentae at or near the axis. Seeds few or numerous, mostly orthotropous, with mealy FIG. 713. The Rock-Rose, Helianthemum Canadense. 714. Flower from -which the petals and stamens have fallen. 715 Magnified cross-section of the ovary ; with a single stamen, showing its hypogynous insertion. 716. Cross-section of a capsule, loculicidally dehiscent ; the seeds therefore borne on the middle of each valve. 717. An ovule. 71S. Plan of the flower. 719. Section of a seed, showing the curved embryo. 394 ILLUSTRATIONS OF THE NATURAL ORDERS. albumen. Embryo curved, or variously coiled or bent. — Ex. Cistus, Helianthemum : a small family ; the flowers often showy. No im- portant properties. Several exude a balsamic resin, such as Lada- num from a Cistus of the Levant. 759. Ol'd. DroseraceSB (Sundeio Family). Small herbs, growing in swamps, usually covered with gland-bearing hairs ; with the leaves rolled up from the apex to the base in vernation (circinnate) : stip- ules none, except a fringe of hairs or bristles at the base of the petioles. Calyx of five equal sepals, persistent. Corolla of five regular petals, withering and persistent, convolute in aestivation. Stamens as many as the petals and alternate with them, or some- times two or three times as many, distinct, withering ; anthers ex- trorse. Styles three to five, distinct or neaidy so, and each two- parted (so as to be taken for ten styles, Fig. 510), and these divis- ions sometimes two-lobed or many-cleft at the apex. Fruit a one- celled capsule, opening loculicidally by three to five valves, with three to five parietal placenta? ; in Dionaea membranaceous, burst- ing irregularly, and with a thick placenta at the base. Seeds usu- ally numerous. Embryo small, at the base of cartilaginous or fleshy albumen. — Ex. Drosera, the Sundew ; and Dionaea (Venus's Fly- trap, Fig. 297, 298), so remarkable for its sensitive leaves, which suddenly close when touched. The styles of the latter are all united into one. 760. Ol'd. PamaSSiacCBB is for the present made for the genus Par- nassia, which was formerly appended to Droseraceoe (for no good reason), and has since been placed by some next to Hypericaceae, by others referred to Saxifragaceas. It is remarkable for having the four or five stigmas situated directly over the pai-ietal placentae (p. 294, note), and for the curious appendages resembling sterile sta- mens before each petal (Fig. 380, 381). 761. Ol'd. IlypericaceBE (St. Johnsioort Family). Shrubs or herbs, with a resinous or limpid juice, and opposite entire leaves, destitute of stipules, and punctate with pellucid or blackish dots. Flowers regular. Calyx of four or five persistent sepals, the two exterior often smaller. Petals four or five, convolute in aestivation, often beset with black dots. Stamens commonly polyadelphous and numer- ous. Ovary one-celled with parietal placentae, or 4 - 5-celled (Fig. 375, 497, 498, 508, 509). Capsule with septicidal dehiscence (Fig. 582), many-seeded. — Ex. Hypericum (St. Johnswort) is the type of this small family. Embryo straight ; albumen little or none. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 395 The plants yield a resinous acrid juice, and a bitter, balsamic ex- tractive matter. 762. Ord. Elaliliacca: (Waterwort Family). Small annual weeds with membranaceous stipules between the opposite leaves, and mi- nute axillary flowers. Sepals and petals three to five. Stamens as many or twice as many as the petals, distinct. Capsule 2 — 5-celled, septicidal or septifragal ; the numerous seeds attached to a persist- ent central axis. Albumen none. — Ex. Elatine is the type of this order, containing a few insignificant weeds. 763. Ord. Caryopliyllaceae (Fink Family). Herbs, with opposite entire leaves ; the stems tumid at the nodes. Flowers regular. Calyx of four or five sepals. Corolla of four or five petals, or sometimes wanting. Stamens as many, or commonly twice as many, as the petals, sometimes reduced to two or three. Styles two to five, stigmatose down the inside. Ovary mostly one-celled, with a central or basilar placenta, forming a pod in fruit. Embryo periph- eric, curved or coiled around the outside of mealy albumen (Fig. 620, 621, 726). — There are five principal suborders, viz. : — 764. Subord. SileilCflB {Pink Family proper) ; in which the sepals are united into a tube, and the petals (mostly convolute in aestiva- tion) and stamens are inserted on the stipe of the ovary, the former with long claws (Fig. 432, 449), and there are no stipules. — Ex. Silene, Dianthus (Pink, Carnation). 765. Subord. Alsilieae (Chickweed Family) ; in which there are no FIG. 720. Hypericum perforatum (St. Johnswort). 721. Its tricarpellary pistil. Cross-section of the capsule. 723. Vertical section of a seed and its embryo. 722. 396 ILLUSTRATIONS OF THE NATURAL ORDERS. stipules, the ovary is sessile, the sepals and petals (imbricated in aestivation) are nearly or quite distinct ; the petals destitute of claws ; and the stamens are inserted into the margin of a small hypogynous disk, which, however, occasionally coheres with the base of the calyx, and becomes perigynous. — Ex. Stellaria, Arenaria, &c. (Chick- weeds). Some are ornamental ; others, such as the common Chickweed, are in- significant weeds. 766. Subord. Ille- cebrecD {Knot wort Family) ; differing from the last main- ly in having sca- rious stipules ; the sepals often united below ; the petals often wanting or ru- dimentary ; the sta- mens manifestly pe- rigynous ; and the fruit more commonly a one-seeded utricle — Ex. Paronychia and Anychia. Spergula has conspicuous petals, and many-seeded capsules ; and so differs from Alsineos only in its stipules. Insignificant weeds. 767. Subord. SclerantheCB {Knawel Family) is like the last, only there are no stipules. — Ex. Scleranthus. 768. Subord. MolluginCiE {Carpet-weed Family) is apetalous with- out stipules, and has the stamens alternate with the sepals when of the same number ; thus effecting a transition to 769. Ol'd. Poi'tulacaccSB {Purslane Family). Succulent or fleshy herbs, with entire exstipulate leaves and usually ephemeral flowers. Calyx mostly of two or three sepals, sometimes cohering with the base of the ovary. Petals five, or rarely more numerous, sometimes none. Stamens variable in number, but when equal to the petals situated opposite them. Styles two to eight, united below. Capsule FIG. 724. Moehringia lateriflora. 725. A magnified flower. 726. Magnified section of a seed, showing the embryo coiled into a ring around the albumen. 727. A'ertical section of a pistil of Spergularia. EXOGENOUS OR DICOTYLEDONOUS TLANTS. 397 with few or numerous seeds, attached to a central basilar placenta, often by slender funiculi. Seed and embryo as in Caryophyllaceoe. — Ex. Portulaca (Purslane, Fig. 389, 588) Claytonia. Chiefly natives of dry places in the warmer parts of the world ; except Claytonia. Insipid or slightly bitter : several are pot-herbs, as the Purslane. Some are ornamental. The farinaceous root of Lewisia rediviva, a native of the dry interior plains of Oregon, is an impor- tant article of food with the natives. 770. Ord. MesembryantliemacCEB {Fig-Marigold Family) consists of succulent plants, with showy flowers opening only under bright sun- shine, containing an indefinite number of petals and stamens, and a many-celled and many-seeded capsule : otherwise much as in Caryo- phyllaceae. — Ex. Mesembryanthemum (Fig-Marigold, Ice-plant) ; chiefly natives of the Cape of Good Hope, flourishing in the most arid situations. 771. Ord. Malvaceae {Mallow Family). Herbs, shrubs, or rarely trees. Leaves alternate, palmately veined, with stipules. Flowers regular, often with an involucel, forming a double calyx. Calyx mostly of five sepals, more or less united at the base, valvate in FIG. 728. Flower of the Purslane ; the calyx cut away at the point where it adheres to the ovary, and laid open. 729. A capsule (pyxis) of the same, transversely dehiscent. 730. Clay- tonia Yirginica (Spring-Beauty). 731. Diagram of the flower. 732. Young fruit and the per- sistent two-leaved calyx. 733. Section of the dehiscing capsule. 734. A seed. 735. The same, vertically divided. 736. The embryo, detached. 34 398 ILLUSTRATIONS OF THE NATURAL ORDERS. aestivation. Petals as many as the sepals, convolute in aestivation, hypogynous. Stamens indefinite, monadelphous, united with the claws of the petals : anthers reniform, confluently one-celled. Pollen hispid (Fig. 483). Ovary several-celled, with the placenta? in the axis; or ovaries several. Fruit capsular, or the carpels separate or separable. Seeds with a little mucilaginous or fleshy albumen. Embryo large, with foliaceous cotyledons, variously incurved or folded. — Ex. Malva (Mallow), Althaea (Hollyhock), Gossypium (Cotton), &c. : a rather large and important family, the herbage, &c. commonly abounding in mucilage, and entirely destitute of un- wholesome qualities. The unripe fruit of Abelmoschus or Hibiscus esculentus (Okra) is used in soups. Althaea officinalis is the Marsh Mallow of Europe, the Guimauve of the French. The tenacious inner bark of many species is employed for cordage. Cotton is the hairy covering of the seeds of Gossypium : the long and slender tubes, or attenuated cells, collapse and twist as the seed ripens, which renders the substance capable of being spun. Cotton-seed yields a good fixed oil. Some species are cultivated for ornament. 772. Ofd. Byttnci'iacece is distinguished from the foregoing by its usually definite stamens, and the two-celled anthers (the cells par- allel), with smooth pollen. — A Melochia and a Hermannia are found in Texas. The rest of the order is tropical or subtropical. Chocolate is made of the roasted and comminuted seeds of Theo- brorna Cacao (a South American tree), mixed with sugar, arnotto, vanilla, and other ingredients. The roasted integuments of the seeds, also, are used as a substitute for coffee. FIG. 737. The Marsh Mallow (Althaea officinalis). 738. One of the kidney-shaped one-celled anthers, magnified. 739. The pistils, magnified. 740. Capsule of Hibiscus Moscheutos, with the persistent calyx and involucel. 741. The same, loculicidally dehiscent. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 399 773. Orel. SterCllIiacefC, very closely allied to the last two, and con- sisting of tropical trees, possesses the same mucilaginous properties (as well as oily seeds), with which bitter and astringent qualities are often combined. The seeds of Bombax, the Silk-cotton tree, are enveloped in a kind of cotton, which belongs to the endocarp and not to the seed ; and the hairs, being perfectly smooth and even, can- not be spun. Canoes are made from the trunk of the huge Bombax Ceiba, in the West Indies. To this order belongs the famous Baobab, or Monkey-bread, of Senegal (Adansonia digitata), some trunks of which are from sixty to eighty feet in circumference ! The fruit resembles a gourd, and serves for vessels ; it contains a subacid and refrigerant, somewhat astringent pulp ; the mucilagi- nous young leaves are also used for food in time of scarcity ; the dried leaves (Lalo) are ordinarily mixed with food, and the bark furnishes a coarse thread, which is made into cordage or woven into cloth. Cheirostemon platanoides is the remarkable Hand-flower tree of Mexico. A plant of the family (Fremontia, Torr.) nearly allied to Cheirostemon has been found in California, by Fremont. 774. Ord. TiliaceOB {Linden Family). Trees or shrubby plants, with alternate leaves, furnished with deciduous stipules, and small jjJecies (such as our Cnidoscolus stimulosus) sting like Nettles. Box- wood is invaluable to the wood-engraver. The purple dye called Turnsole is from Crozophora tinctoria. Another most important product of this order is Caoutchouc, which is yielded by various plants of different families ; but the principal supply of the article (that of Para, Demarara, and Surinam) is furnished by species of Siphonia. 910. Ord. EmpetracCBB {Crowberry Family). Low, shrubby ever- greens, with the aspect of Heaths ; the leaves crowded and acerose, with small (dioecious or polygamous) flowers produced in the axils. Calyx consisting of regular imbricated sepals, or represented by im- bricated bracts. Stamens few : pollen of four grains coherent in one, as in Heath. Ovaiy three- to nine-celled, with a single erect ovule in each cell : style short or none : stigmas lobed and often laciniated. Fruit a drupe, with from three to nine bony nucules. Seeds albuminous ; the radicle inferior. — Ex. Empetrum, Ceratiola, Corema; unimportant plants. Probably no more than apetalous Ericaceae ; but the stigmas are peculiar. 911. Ord. UrticaceSB {Nettle Family), shrubs, or herbs, with stipules, often with milky juice, and diclinous or polygamous, rarely perfect flowers, furnished with a regular calyx ; which is free from the one- FIG. 1148. Branch of Ceratiola ericoides in fruit. 1149. Magnified staminate flower, with its bracts. 1150. The two stamens, with an inner bract or sepal. 1151. Magnified pistillate flower, with its imbricated bracts. 1152. The pistil separate ; one of the cells laid open by a vertical section, showing the erect ovule. 1153. Drupe, with the persistent scales at the base. 1154. Transverse section of its endocarp, or two nucules, with the enclosed seed and embryo. 1155. Vertical section of the seed. 40* 474 ILLUSTRATIONS OP THE NATURAL ORDERS. celled (sometimes two-celled) ovary and the always one-celled and one-seeded fruit, but sometimes enclosing it. Stamens as many as the lobes of the calyx and opposite them, or sometimes fewer. Em- bryo large ; cotyledons mostly broad ; the radicle superior in the fruit. Stipules often deciduous. A large and greatly diversified order, comprising at least four well-marked suborders. 912. Suboi'd. UimaceSB (Elm Family). Trees or shrubs, with a watery juice, alternate rough leaves, perfect or merely polygamous flowers, two styles or stigmas ; the ovary either one- or two-celled, with one ovule suspended from the summit of each. Fruit either a samara (Fig. 578), with a straight embryo and no albumen, as in ^m ^»£| m^ <7 the Elm (Uhnus) ; or a drupe with a curved embryo and scanty albumen, as in Celtis (Hackberry), the type of the tribe Celtide^e. Timber-trees. The inner bark of the Slippery Elm is highly charged with mucilage. Hackberries are edible. 913. Subord. ArtocarpeSB (Bread-fruit Family) ; which are chiefly tropical trees or shrubs with a milky or yellow juice ; the monoe- cious or dioecious flowers mostly aggregated into fleshy heads, and FIG. 1156. Flower of the Slippery Elm. 1157. Calyx laid open and the ovary divided ver- tically. 1158. Fruit, the cell laid open to show the single seed. 1159. The latter magnified. 1160. Its embryo. FIG. 1161. Branch of Celtis Americana, in flower. 1162. Enlarged flower, divided verti- cally. 1163. Drupe, the flesh divided to show the stone. 1163'. The coiled embryo. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 475 forming a multiple fruit, or else enclosed in a dry or succulent invo- lucre. Styles or stigmas commonly two. Ovary ripening into an achenium. Seeds with or without albumen. — Ex. Artocarpus (the Bread-fruit), Morus (the Mulberry, Fig. 593-595), Madura (the Osage Orange), Ficus (the Fig, Fig. 590-592). The fruit is often innocent and edible, at least when cooked ; while the milky juice is more or less acrid or deleterious. It also abounds in Caout- chouc. ; much of which is obtained from some South American trees of this order, and from Fiscus elastica in Java. In one instance, how- ever, the milky juice is perfectly innocent ; that of the famous Cow- tree of South America, which yields a rich and wholesome milk. One of the most virulent of poisons, the Bohon Lpas, is the concrete juice of Antiaris toxicaria of the Indian Archipelago. The Bread- fruit is the fleshy receptacle and multiple fruit of Artocarpus. Fustic is the wood of the South American Madura tinctoria ; the wood of our own Madura or Osage Orange is used by the "Western Indians for bows. The resin called Gttm Lac exudes and forms small grains on the branches of the celebrated Banyan-tree (Ficus Indica, Fig. 142). 914. SubOl'd. UrticeSB (True Nettle Family) ; which are herbs in colder countries, but often shrubs or trees in the tropics, with a watery juice, often with stinging hairs ; the monoecious or dioecious flowers mostly loose, spicate, or panicled. Ovule orthotropous. Ovary always one-celled, and style or stigma one ; the achenium usually surrounded by a dry and membranous calyx. Embryo straight, in fleshy albumen. — Ex. Urtica (the Nettle), &c. Innoc- uous plants, except for the stinging hairs of many species. The inner bark of Nettles yields very tough and slender fibres. 915. Subord. CannabillCSD (Hemp Family). Annual erect herbs, or perennial twining plants, with a watery juice and dioecious flow- ers ; the staminate flowers racemose or panicled ; the pistillate glom- erate, or imbricated with bracts, and forming a kind of strobile-like anient ; their calyx one-leaved. Stigmas two. Ovary one-celled, with an erect orthotropous ovule. Embryo coiled or bent : albumen none. — Ex. Cannabis (the Hemp), Humulus (the Hop). Hops are the catkins with large bracts ; the bitter and sedative principle chiefly resides in the yellow grains that cohere to the scales and cover the fruit. The leaves of Hemp, when grown in a hot climate, are powerfully stimulant and narcotic, and are used in the East for intoxication. The inner bark is used for cordage, &c. 476 ILLUSTRATIONS OF THE NATURAL ORDERS. 916. Ord. Plataiiacesc (Plane-tree Family) consists of the single genus Platanus (Plane-tree, Button-ball), with one Asiatic and one or more North- American species : fine trees, with a watery juice, and alternate palmately-lobed leaves, with sheathing stipules. Flow- ers in globose amentaceous heads ; both kinds destitute of floral envelopes. Fruit a one-seeded club-shaped little nut, the base fur- nished with bristly hairs. Seed albuminous. 917. Ord. JllglaildaceEE {Walnut Family). Trees, with alternate pinnated leaves, and no stipules. Flowers monoecious. Sterile flowers in aments, with a membranous irregular calyx, and indefinite stamens. Fertile flowers few, clustered, with the calyx adherent to the incompletely two- to four-celled but one-ovuled ovary, the limb small, three- to five-parted ; sometimes with as many small petals. Ovule orthotropous. Fruit drupaceous ; the exocarp fibrous-fleshy and coherent, or else coriaceous and dehiscent : endocarp bony. Seed four-lobed, without albumen. Embryo oily : cotyledons cor- rugate, two-cleft. — Ex. Juglans (Walnut, Butternut), Carya (Hick- ory, Pecan, &c). — The greater part of the order is North Ameri- can. The timber is valuable ; especially that of Black Walnut, for cabinet-work, and that of Hickory, for its great elasticity and strength. The young fruit is acrid : the seeds of several are de- licious ; those of the Walnut abound in a drying oil. 918. Ol'd. CupilliferSB {Oak Family). Trees or shrubs, with alter- nate and simple straight-veined leaves, and deciduous stipules. Flowers usually monoecious. Sterile flowers in aments, with a scale-like or regular calyx, and the stamens one to three times the number of its lobes. Fertile flowers solitary, two to three together, or in clusters, furnished with an involucre which encloses the fruit or forms a cupule at its base. Ovary adnate to the calyx, and crowned by its minute or obsolete limb, two- to six-celled with one or two pendulous ovules in each cell : but the fruit is a one-celled and one-seeded nut (Fig. 576). Seed without albumen. Embryo with thick and fleshy cotyledons, which are sometimes coalescent. — Ex. Quercus (the Oak), Fagus (the Beech), Corylus (the Hazel- nut), Castanea (the Chestnut), &c. Some of the principal forest- trees in northern temperate regions. The valuable timber and edible nuts they furnish are too well known to need enumeration. The astringent bark and leaves of the Oak abound in tannin, gallic acid, and a bitter extractive called Quercine ; they are used in tan- ning and dyeing. Quercitron is obtained from the Quercus tine- EXOGENOUS OR DICOTYLEDONOUS PLANTS. 477 toria. Galls are swellings on the leafstalks, &c., when wounded hy certain insects ; those of commerce are derived from Q. infectoria of Asia Minor. Cork is the exterior corky layer of the bark of the Spanish Quercus Suber. 919. Ord. Myricacece (Sweet- Gale Family). Shrubs, with alter- nate and simple aromatic resinous-dotted leaves, monoecious or dioe- cious. Differs from the next principally by the one-celled ovary, with a single erect orthotropous ovule, and a drupe-like nut. — Ex. Myrica, Comptonia, the Sweet Fern. The drupes of M. cerifera (our Candleberry or Bayberry) yield a natural wax. 920. Ol'd. BetlllaceSB (Birch Family). Trees or shrubs, with al- ternate and simple straight-veined leaves, and deciduous stipules. Flowers monoecious ; those of both kinds in aments (Fig. 312), and commonly achlamydeous, placed three together in the axil of each three-lobed bract. Stamens definite. Ovary two-celled, each cell with one suspended ovule : styles or stigmas distinct. Fruit mem- branaceous or samara-like, one-celled and one-seeded, forming with the three-lobed bracts a kind of strobile. Albumen none. — Ex. Betula (the Birch), Alnus (Alder). The bark is sometimes astrin- FIG. 1164. Quercus Chinquapin in fruit : a, cluster of sterile aments. 1165. A magnified Btaminate flower. 1166. Transverse section of an ovary, showing the three cells with two ovules in each. 1167. The immature seed, with the accompanying abortive ovule. 1168. The nut (acorn), in its scaly involucre, or cupule. 1169. Vertical section of the same, and of the included seed and embryo, showing the thick cotyledons. 478 ILLUSTRATIONS OF THE NATURAL ORDERS. gent, and that of the Birch is aromatic. The peculiar odor of Russia leather is said to be owing to a pyroligneous oil obtained from Betula alba, or White Birch. 921. Ol'd. SalicaceOB (Willow Family). Trees or shrubs, with al- ternate simple leaves, furnished with stipules. Flowers dioecious ; both kinds in aments, and destitute of floral envelopes (achlamyde- ous), one under each bract. Stamens two to several, sometimes monadelphous. Ovary one-celled, many-ovuled ! Styles or stigmas two, often two-cleft. Fruit a kind of follicle opening by two valves. Seeds numerous, ascending, furnished with a silky coma ! Albu- men none. — Ex. Salix (Willow, Fig. 415-419), and Populus (the Poplar). Trees with light and soft wood : the slender, flexible shoots of several Willows are employed for wicker-work. The bark is bitter and tonic, and contains a peculiar substance (Salicine), which possesses febrifugal qualities. The buds of several Poplars exude a fragrant balsamic resin. FIG. 1170. Young ament of staminate flowers of a Birch (Betulafruticosa?). 1171. One of the three-lobed scales of the same, enlarged, showing the flowers (stamens) on the inner side. 1172. Ament of pistillate flowers. 1173. Branch in fruit. 1173'. One of the scales with its three flowers (pistils) seen from within. 1174. Magnified section of one of the two-celled pis- tils, displaying the ovule suspended from the summit of each cell. 1175. The pistils (with their subtending bract) in a more advanced state. 1176. Magnified cross-section of one of the ovaries. 1177. The mature fruit, with the cell divided vertically ; the single seed occupying the cavity ; a mere trace of the other cell being visible. 1178. The seed removed. 1179. The embryo. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 479 Subclass 2. Gymnospermous Exogenous Plants. Ovules, and consequently the seeds, naked, that is, not enclosed in an ovary (560) ; the carpel being represented either by an open scale, as in Pines ; or by a more evident leaf, as in Cycas ; or else wanting altogether, as in the Yew. 922. Ol'd. ConiferSC {Pine Family). Trees or shrubs, with branch- ing trunks, abounding in resinous juice (the wood chiefly consisting of a tissue somewhat intermediate between ordinary woody fibre and vessels, and marked with circular disks) ; the leaves mostly evergreen, scattered or fascicled, usually rigid and needle-shaped or FIG. 1180. Carpellary scale of Cupressus sempervirens (the true Cypress), seen from with- in, and showing the numerous orthotropous ovules that stand on its hase. 1181. Branch of Abies Canadensis (Hemlock Spruce), with lateral staminate flowers, and a fertile strobile. 1182. Staminate anient, magnified. 1183. Carpellary scale of a fertile anient, with its bract. 1184. Similar fertile scale, more magnified and seen from within ; showing the two ovules ad- herent to its base: one of them (the left) laid open. 1185. The scale in front, nearly of the natural size, its inner surface occupied by the two seeds. 1186. Polycotyledonous embryos of Abies and Cypress. 1187. Vertical section of an embryo. 1188. Strobile of Taxodium dis- tichum (Suborder Cupressineae). 480 ILLUSTRATIONS OF THE NATURAL ORDERS. linear, entire. Flowers monoecious or dioecious, commonly amenta- ceous. Staminate flowers consisting of one or more (often mona- delphous) stamens, destitute of calyx or corolla, ai*ranged on a com- mon rhachis so as to form a kind of loose anient. — The particular structure of the flowers and fruit varies in the subordinate groups, chiefly as follows : — 923. Sllboril. AbietineBB {Fir, or Pine Family proper). Fertile aments formed of imbricated scales ; which are the flat and open carpels, and bear a pair of ovules adherent to their base, with the foramen turned downwards (Fig. 511). Scales subtended by bracts. Fruit a strobile or cone (Fig. 596). Integument of the seed cori- aceous or woody, more or less firmly adherent to the scale. Em- bryo in the axis of fleshy albumen, with two to fifteen cotyledons. Buds scaly. 924. Sllboril. ClipressineOB {Cypress Family). Fertile aments of few scales crowded on a short axis, or more numerous and peltate, not bracteate. Ovules one, two, or several, borne on the base of the scale, erect (the foramen looking towards its apex, Fig. 516, 1180). Fruit an indurated strobile, or sometimes fleshy and with the scales concreted, forming a kind of drupe. Integument of the seed mem- branous or bony. Cotyledons two or more. Anthers of several parallel cells, placed under a shield-like connective. Buds naked. — Ex. Cupressus (Cypress), Taxodium (American Cypress), Juni- perus (Juniper, Bed Cedar). 925. Sllbord. Taxilieae (Yeto Family). Fertile flowers solitary, terminal, consisting merely of an ovule, forming a drupaceous or nut- like seed at maturity. There are, therefore, no strobiles and no carpellary scales. Embryo with two cotyledons. Buds scaly. — Ex. Taxus (the Yew), Torreya. 926. It is unnecessary to specify the important uses of this large and characteristic family, which comprises the most important tim- ber-trees of cold countries, and also furnishes resinous products of great importance, such as turpentine, resin, pitch, tar, Canada bal- sam, &c. The terebinthine Juniper-berries are the fruit of Juni- perus communis. The Larch yields Venetian turpentine. The powerful and rubefacient Oil of Savin is derived from J. Sabina of Europe : for which our nearly allied J. Virginiana (Bed Cedar) may be substituted. The leaves of the Yew are narcotic and dele- terious. The bark of Larch, and especially of the Hemlock-Spruce, is used for tanning. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 481 927. Ord. CycadaccCB {Cycas Family). Tropical plants, with an unbranched cylindrical trunk, increasing, like Palms, by a single terminal bud ; the leaves pinnate and their segments more or less rolled up from the apex (circulate) in vernation, in the manner of Ferns. Flowers dioecious ; the staminate in a strobile or cone ; the pistillate also in strobiles, or else (in Cycas) occupying contracted and partly metamorphosed leaves ; the naked ovules borne on its margins. — Ex. Cycas, Zamia. — A kind of Arroioroot is obtained from these thickened stems, or caudexes, as from our dwarf Florida species (the Coontie of the aborigines) ; and a coarse Sago from the trunk of Cycas. FIG. 1189. Zamia integrifolia (the Coontie of Florida). 1190. Section of the sterile ament. 1191. One of its scales detached, bearing scattered anthers. 1192. Fertile anient, from which a quarter-section is removed. 1193. A pistillate flower, consisting of two ovules pendent from the thickened summit of the carpellary scale. 1194. A drupaceous seed, from which a part of the pulpy outer portion, at the apex, is removed. 1195. Vertical section through the seed (of the natural size), showing the pulpy outer coat, the hard inner integument, the albumen, and the embryo. 41 482 ILLUSTRATIONS OF THE NATURAL ORDERS. Class II. Endogenous or Monocotyledonous Plants. Stem not distinguishable into bark, pith, and wood ; but the latter consisting of bundles of fibres and vessels irregularly imbeded in cellular tissue ; the rind firmly adherent ; no medullary rays, and no appearance of concentric layers : increase in diameter effected by the deposition of new fibrous bundles, which at their commence- ment occupy the central part of the stem. Leaves seldom falling off by an articulation, sheathing at the base, usually alternate, entire, and with simple parallel veins (nerved). Floral envelopes when present mostly in threes, never in fives ; the calyx and corolla most commonly undistinguishable in texture and appearance. Embryo with a single cotyledon ; or, if the second is present, it is much smaller than the other, and alternate with it. Conspectus of the Orders. Group 1. Flowers on a spadix, furnished with a double and free perianth (answering to calyx and corolla). Ovary one- to three-celled, with a single ovule in each cell. Embryo in hard albumen. — Trees with unbranched columnar trunks. Palm^e. Group 2. Flowers on a spadix ; with the perianth simple and free, or reduced to a few scales, or commonly altogether wanting. — Cbiefly herbs. Terrestrial. Fruit nut-like, or comose, one-seeded. Typhace^e. Terrestrial, mostly with a spathe. Fruit baccate. Arace^;. Aquatic (floating or immersed). Flowers developed from the edge of the floating frond. LemnacevE. Flowers axillary or on a spadix. Naiadace>e. Group 3. Flowers not spadiceous, furnished with a double and free perianth (calyx and corolla). Ovaries several, distinct, or sometimes united. Aquat- ic herbs. Alismace2E. Group 4. Flowers with a simple or doable perianth, which is adherent to the ovary, regular, developed from a spathe, polygamous or diclinous. Ovary one-celled with parietal placenta?, or 3 - 9-celled. Seeds destitute of albu- men. — Aquatics. Hydrocharidace;e. Group 5. Flowers perfect with the double or 6-merous perianth adherent to the ovary (or more or less free in some Hamiodoracea; and Bromeliacea;). Seeds with albumen, except perhaps the very minute ones of Orchidacere, &c. Leaves parallel-veined. ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS. 483 Stamens gynandrous, 1 or 2 fertile. Flower irregular. Orchidace^e. Stamens not gynandrous. Flower irregular. Fertile stamen I, inferior. Zingii!Erace^;. Fertile stamen 1, superior. Cannace^e. Fertile stamens mostly 5, the sixth abortive. Musaceje. Stamens not gynandrous, regularly 3 or 6. Anthers extrorse. Stamens 3, before the sepals. Iridace;e. Anthers introrse, when 3 before the inner perianth. Anther-cells separated by a broad connective. Burmanniace;e. Anther-cells approximate or joined. Leaves not scurfy. Stems from bulbs. Amaryllidace^e. Leaves scurfy or woolly. No bulbs. Terrestrial. Stamens 3 or 6. Hjemodoracejs. Mostly epiphytes. Stamens 6. Bromeliace.e. Group 6. Flowers dioecious, with a 6-merous perianth adherent to the ovary. Seeds with a minute embryo in hard albumen. Leaves ribbed and netted- veined, articulated with the stem. Dioscoreace^e. Group 7. Flowers dioecious or perfect ; the regular perianth free from the ovary. Styles or sessile stigmas distinct. Embryo minute in hard albumen. Leaves more or less netted-veined. Smilace;e. Group 8. Flowers perfect, not from a spathe, with the regular 6-merous peri- anth free from the ovary. Seeds anatropous, with albumen. Perianth not glumaceous. Leaves parallel-veined. Anthers introrse. Styles united into one. Liliace^e. Anthers extrorse. Styles mostly separate. Melanthace.e. Perianth glumaceous. Styles united into one. Juncace^;. Group 9. Flowers perfect, developed from a spathe, commonly somewhat ir- regular, the 6-merous perianth free from the ovary. Seeds anatropous, with albumen. Aquatics. Pontederiace-E. Group 10. Flowers with a double or imbricated perianth, free from the ovary ; the exterior divisions (sepals) herbaceous or glumaceous ; the inner (pet- als) petaloid, free from the one- to three-celled ovary. Seeds 2, 3, or many, orthotropous ; the embryo at the extremity of the albumen farthest from the hilum. Flowers perfect. Sepals herbaceous. Petals colored. CojimelynacEjE. Flowers perfect, capitate. Sepals and bracts glumaceous. Xyridaceje. Flowers monoecious or dioecious, capitate. Eriocaulonace^e. Group 11. Flowers imbricated with glumaceous bracts (glumes), and disposed in spikelets ; the proper perianth none or rudimentary. Ovary one-celled, one-ovuled. Seeds anatropous. Embryo at the extremity of the albumen next the hilum. Sheaths of the leaves closed. Glume or bract single. Cyperace.£:. Sheaths open. Glumes mostly in pairs. Gramine^e. 484 ILLUSTRATIONS OF THE NATURAL ORDERS. 928. Ol'd. Palms (Palms). Chiefly trees, with unbranched cylin- drical trunks growing by a terminal bud. Leaves large, clustered, fan-shaped or pinnated, plaited in vernation. Flowers small, per- fect or polygamous, mostly with a double (6-merous) perianth ; the stamens usually as many as the petals and sepals together. Ovary 1 _ 3-celled, with a single ovule in each cell. Fruit a drupe or berry. Seeds with a cartilaginous albumen, often hollow ; the embryo placed in a small separate cavity. — Ex. Palms, the most majestic race of plants within the tropics, and of the highest value to mankind, are scarcely found beyond the limits of these favored regions. The Date-tree (Phoenix dactylifera, the leaves of which are the Palms of Scripture), a native of Northern Africa, endures the climate of the opposite shores of the Mediterranean : while in the New World, Chamrerops Palmetto (Fig. 184), the only arborescent species of the United States, and one or two low Palms with a creeping caudex (Dwarf Palmetto), extend from Florida to North Carolina. Palms afford food and raiment, wine, oil, wax, flour, sugar, salt, thread, weapons, utensils, and habitations. The Cocoanut (Cocos nucifera) is perhaps the most important, as well as the most widely diffused species. Besides its well-known fruit, and the beverage it contains, the hard trunks are employed in the construction of huts ; the ter- minal bud (as in our Palmetto and other Cabbage Palms) is a deli- cious article of food ; the leaves are used for thatching, for making FIG. 1195. Branch of the inflorescence of Chamacrops hystrix (Blue Palmetto). 1197. A sterile flower. 1198. Perfect flower, with the calyx and corolla removed. 1199. Same, with three of the stamens removed, so as more distinctly to show the three somewhat united carpels. 1200. One of the carpels enlarged, seen laterally. 1201. Same, with a section of its inner face, showing the ovule or young seed. 1202. Vertical section of a young cocoanut, showing the hollow albumen ; and also the small embryo in a separate little cavity. 1203 Section of a Palm-stem. ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS- 485 hats, baskets, mats, fences, for torches, and for writing upon ; the stalk and midrib for oars ; their ashes yield abundance of potash ; the juice of the flowers and stems (replete with sugar, which is sometimes separated under the name of Jagery) is fermented into a kind of wine, or distilled into Arrack ; from its spathes (as from some other Palms), when wounded, flows a grateful laxative bever- age, known in India by the name of Toddy ; the rind of the fruit is used for culinary vessels ; its tough, fibrous, outer portion is made into very strong cordage {Coir rope) ; and an excellent fixed oil is copiously expressed from the kernel. Sago is procured from the trunks of many Palms, but chiefly from species of Sagus of Eastern India. Canes and Rattans are the slender, often prostrate, stems of species of Calamus. — The Phytelephas, or so-called Ivory Palm, of Central America, the seeds of which are the Vegetable Ivory now so commonly used by the turner, in place of ivory, for small articles, is not a genuine Palm, having polygamo-dioecious flowers with a rudimentary perianth, or none at all, &c. It is proposed as the type of an order (Phytelepiianteje) ; but may for the present be ap- pended to the Palms ; between Avhich and the succeeding orders stands the 929. Ord. PaildanaceSB ; tropical arborescent plants, of Palm-like port, but their simplified diclinous flowers destitute of a perianth, the one-celled ovary many-ovuled. The seeds of Pandanus (the Screw- Pine, Fig. 140), &c. are eatable. From the young leaves of Car- ludovica the famous Panama hats are braided. 930. Ol'd. TypliaceOE {the Cat-tail Family) consists of two genera ; namely, Typha (the Cat-tail), and Sparganium (Bur-reed), of no important use. They are spadiceous plants with excessively re- duced flowers, having no perianth. 931. Ol'd. Araceae {Arum Family). Herbs, with a fleshy corm or rhizoma, often shrubby or climbing plants in the tropics ; the leaves sometimes compound or divided, commonly netted-veined. Flowers mostly on a spadix (often naked at the extremity), usually surround- ed by a spathe or hood (Fig. 313, 314). Flowers commonly monoe- cious, and destitute of envelopes, or with a single perianth. Ovary one- to several-celled, with one or more ovules. Fruit a berry. Seeds with or without albumen. — Ex. Arum, Calla, Symplocarpus (Skunk-Cabbage), Orontium, Acorus (Sweet Flag) : the three latter bear flowers furnished with a perianth. — All are endowed with an acrid volatile principle, which is merely pungent and aromatic in 41* 48 G ILLUSTRATIONS OF THE NATURAL ORDERS. Sweet Flag (Acorus Calamus), but extremely sharp in Arum, Indian Turnip, &c. The acrid principle of these plants is volatile, and is dissipated by heat or in drying. "When cooked, their farina- ceous conns are eatable. That of Taro of the South Sea Islands, and some other species of Colocasia, are important articles of food. Symplocarpus fcetida exhales a strong odor, very like that of the skunk, whence, as it has large and roundish leaves in a radical clus- ter, it is called Skunk Cabbage. The roots have been used in medi- cine as an antispasmodic. 932. Ord. LeiMaceEB (Duckweed Family), consisting chiefly of Lemna (Duckweed or Water Flax-seed) ; floating plants, with their roots (if any) arising from the bottom of a flat frond, and hanging loose in the water ; their flowers produced from the margin of the frond, bursting through a membranous spathe ; the sterile, of one or FIG. 1204. Young leaf, and 1205, spathes and flowers, of Symplocarpus foetida. 1206. A separate flower when young. 1207. A detached sepal and stamen seen from within. 120S. An anther seen from the front. 1209. The spadix or collective head in fruit ; a quarter-section removed, showing sections of the immersed seeds. 1210. A seed detached, of the natural size. 1211. Section of the seed, with its large globular embryo and plumule : in this plant there i3 no albumen. ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS. 487 two stamens ; the fertile, of a one-celled ovary ; in fruit a utricle : they are a kind of minute and greatly reduced AraceaB, connecting that order with the next. 933. Ord. MadaceSB (Pondiceed Family). "Water-plants, with cellular leaves, and sheathing stipules or bases : the flowers incon- spicuous, sometimes perfect. Perianth simple and scale-like, or none. Stamens definite. Ovaries solitary, or two to four and dis- tinct, one-seeded. Albumen none. Embryo straight or curved. — Ex. Potamogeton (Pondweed), Najas, Ruppia, Zostera ; the two latter in salt or brackish water. 934. Ord. AlismaceCB {Water-Plantain Family). Marsh herbs, with the leaves and scapes usually arising from a creeping rhizoma ; the former either linear, or bearing a flat limb, which is ribbed or nerved, but the veinlets commonly reticulated. Flowers regular, perfect or polygamous, mostly in racemes or panicles, not on a spa- dix. Perianth double, the three petals commonly different from the sepals, so as evidently to represent a calyx and a corolla. Seeds soli- tary in each carpel or cell, straight or curved, destitute of albumen. — Ex. Alisma (Water-Plantain), Sagittaria (Arrowhead); belong- ing to the proper Alisma Family, which has the seed (and conse- FIO. 1212. Whole plant of Lemna minor, magnified, bearing a staminate monandrous flow- er. 1213. An individual with a diandrous perfect flower ; which at 1214 is seen separate, with its spathe, highly magnified. 1215. Flower of Lemna gibba, much magnified. 1216. Vertical highly magnified section of the pistil and the contained ovule of Lemna minor. 1217. The fruit, and 1218, its section, showing the seed. 1219. Section through the highly magnified seed and large embryo. 488 ILLUSTRATIONS OF THE NATURAL ORDERS. quently the embryo) curved or doubled upon itself. Triglochin and Scheuchzeria chiefly constitute the suborder Juncagineje ; where the seed and embryo are straight, and the petals (if present) are greenish like the calyx. Slightly acrid plants, and some of them astringent. 935. Ord. BlltomacefE, represented by Butomus, the Flowering- Rush of Europe, and three small tropical genera, is a form of the last with many ovules attached to the whole face of the carpels : these are separate or combined. Some have a milky juice. 936. Ord. Hydrocliaridaceffi (Frog's-bit Family) consists of a few aquatic herbs, with dioecious or polygamous regular flowers on scape- like peduncles from a spathe, and simple or double floral envelopes, which in the fertile flowers are united in a tube, and adnate to the 1 — 6-celled ovary, more commonly one-celled with three parietal placentas. Seeds numerous, without albumen. — Ex. Limnobium, Vallisneria, Anacharis. 937. Ol'd. Orcllidaceae (Orchis Family). Herbs, of varied aspect and form ; distinguished from the other orders with an adnate ovary, and from all other plants, by their irregular flowers, with a perianth FIG. 1220. Raceme or spike of Triglochin palustre. 1221. Enlarged flower. 1222. A petal and stamen. 1223. The club-shaped capsule. 1224. A magnified seed, exhibiting the rhaphe and chalaza. 1225. Embryo of the same. 1226. Vertical section of the same, bringing the plumule to view. 1227. Cross-section (more magnified), showing the cotyledon wrapped around the plumule. FIG. 1228. Leaf, and 1229, flower, of Alisma Plantago. 1230. More enlarged flower, with the petals removed. 1231. Carpel, with the ovary divided, showing the doubled ovule. 1232. Vertical section of the germinating seed of Alisma Damasonium ; a, the cotyledon ; 6, the plu- mule ; c, the protruding radicle. ENDOGENOUS OR MONOCOTYLEDONOUS TLANTS. 489 of six parts ; their single fertile stamen (or in Cypripeclium their two stamens) coherent with the style (composing the column) ; their pollen usually combined into two or more granular or waxy masses (pollinia) ; the ovary one-celled, with three parietal placentae, covered with numerous minute seeds. — Ex. Orchis, Cypripedium (Ladies' Slipper), Arethusa, &c. In the tropics many are Epiphytes (149, Fig. 144). Many are cultivated for their beauty and singu- larity. The tuberiferous roots are often filled with a very dense mucilaginous or glutinous substance (as those of our Aplectrum, thence called Putty-root). Of this nature is the Salep of commerce, the produce of some unascertained species of Middle Asia. The fragrant Vanilla is the fleshy fruit of Vanilla planifoha and other tropical American species. The roots of Cypripedium are used as a substitute for Valerian. 938. Oril. ZingibCMCete {Ginger Family) consists of some mostly showy tropical aromatic herbs, the nerves of their leaves diverging FIG. 1233. Orchis spectabilis : a, a separate flower. 1234. Column (somewhat magnified), from which the other parts are cut away : the two anther-cells opening and showing the pollen- masses. 1235. Magnified pollen-mass, with its stalk. 1236. Arethusa bulbosa. 1237. The column, enlarged : the anther terminal and opening by a lid. 1238. Magnified anther, with the lid removed, showing the two pollen-masses in each cell. 490 ILLUSTRATIONS OF THE NATURAL ORDERS. from a midrib ; the adnate perianth irregular and triple (having a corolla of two series as well as a calyx) ; fertile stamen one, on the anterior side of the flower, free ; the fruit a three-celled capsule or berry ; the seeds several : with the embryo in a little sac at one extremity of the farinaceous albumen. — There are, in fact, six stamens in the androecium, the three exterior petaloid and forming the so-called inner corolla, and two of the inner verticel are sterile. — Their properties and economical uses are well represented by the pungent aromatic rootstock of Ginger (Zingiber officinale), Galin- gale (Alpinia Galanga, &c), the seeds of Cardamon, &c. The same cordial qualities in lesser degree exist in the roots of Curcuma longa, &c. which furnish the coloring matter called Turmeric ; while other species yield starch, like the closely allied 939. Ol'd. CannaceOB {Arrowroot Family), which also consists of trop- ical plants, differs from the preceding chiefly in the want of aroma, and in having the single fertile stamen posterior, with a one-celled anther. — Ex. Maranta arundinacea, Avhich yields the Arrowroot of the "West Indies ; the tubers of which are filled with starch. 940. Ol'd. MusaceSB {Banana Family). Tropical plants, of which the Banana and Plantain are the type ; distinguished by their simple perianth and five or six perfect stamens. The fruit is an important staple of food in the tropics ; the gigantic leaves are used in thatching ; and the fibres of Musa textilis yield Manilla hemp, as well as a finer fibre from which some of the most delicate India mus- lins are made. 941. Ol'd. Burinaillliacese consists of small, mostly tropical, annual herbs, commonly with a one-celled ovary and three parietal placentas, (but in several the ovary is three-celled) ; differing from Orchidaceae by their regular flowers with three stamens ; and from Iridaceaa by the position of these before the inner divisions of the perianth, the introrse anthers, &c. — Ex. Burmannia and Apteria, of the South- ern States. 942. Ord. Il'idaceSB {Iris Family). Perennial herbs ; the flower- stems springing from bulbs, corms, or rhizomas, rarely with fibrous roots, mostly with equitant leaves. Flowers regular or irregular, showy, often springing from a spathe. Perianth with the tube ad- herent to the three-celled ovary, and usually elongated above it ; the limb six-parted, in two series. Stamens three, distinct or monadel- phous ; the anthers extrorse ! Stigmas three, dilated or petaloid ! Seeds with hard albumen. — Ex. Iris, Crocus. The rootstocks, ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS. 491 corms, &c. contain starch, with some volatile acrid matter. Those of Iris cristata are very pungent ; those of I. versicolor, &c. are drastic. Orris-root is the dried rhizoma of Iris florentina, of South- ern Europe. The true Saffron consists of the dried orange-colored stigmas of Crocus sativus. 943. Ord. AraaryllidacCEB (Amaryllis Family). Bulbous plants (sometimes with fibrous roots), bearing showy flowers mostly on scapes. Perianth regular, or nearly so ; the tube adherent to the ovary, and often produced above it, six-parted. Stamens six, dis- tinct, with introrse anthers. Stigma undivided or three-lobed. Fruit a three-celled capsule or berry. Seeds with fleshy albumen. — Ex. Amaryllis, Narcissus, Crinum, &c. ; mostly ornamental plants. The bulbs acrid, emetic, &c. : those of Hamaanthus (with whose juice the Hottentots poison their arrows) are extremely venomous. The fermented juice of Agave is the intoxicating Pulque of the Mexicans. Hypoxys, which has been taken as the type of an order, may prop- erly be referred to this family. FIO. 1239. Iris cristata. 1240. The summit of the style, petaloid stigmas, and stamens. 1241. Vertical section of the ovary (the equitant leaves cut away) and long tube of the peri- anth. 1242. Cross-section of the pod. 1243. Seed. 1244. Enlarged section of the same, show- ing the embryo, &c. 492 ILLUSTRATIONS OF THE NATURAL ORDERS. 944. Ol'd. BromeliaceEB {Pine-Apple Family) consists of American and chiefly tropical plants ; with rigid and dry channelled leaves, often with a scurfy surface, a mostly adnate perianth of three sepals and three petals, and six or more stamens ; the seeds with mealy albumen. — Ex. Ananassa, the Pine- Apple ; the fine fruit of which is formed by the consolidation of the imperfect flowers, bracts, and receptacle into a succulent mass. Tillandsia, the Black Moss or Long Moss (which, like most Bromelias, grows on the trunks and branches of trees in the warmer and humid parts of America), has the ovary free from the perianth. 945. Ol'd. IIiClllOlloraceBB {Bloodioort Family) is composed of peren- nial herbs, with fibrous roots, equitant or ensiform leaves ; which, with the stems and flowers, are commonly densely clothed with woolly hairs or scurf. Perianth with the tube either nearly free from, or commonly adherent to, the three-celled ovary; the limb six-cleft, regular. Stamens six, or only three, with introrse anthers. Style single, the stigma standing over the dissepiments of the ovary. Embryo in cartilaginous albumen. — Ex. Lachnanthes (Red-Eoot), Lophiola. — Some have a red juice. The roots are astringent and tonic, especially in Aletris. 946. Ol'd. DiosCOl'eaceoe ( Tarn Family) consists of a few twining plants, with large tuberous roots or knotted rootstocks ; distinguished among Endogens by their ribbed and netted-veined leaves, with dis- tinct petioles, and by their inconspicuous dioecious flowers, with the perianth in the pistillate flowers adherent to the ovary; the limb six-cleft in two series. Stamens six. Ovary three-celled, with only one or two ovules in each cell : styles nearly distinct. Fruit often a three-winged capsule. Albumen cartilaginous. — Ex. Dioscorea. The tubers of one or or more species, filled with starch and mucilage (but more or less acrid until cooked), are Yams, an important article of food in tropical countries. 947. Ol'd. SmilacefB (Smilax Family) is also remarkable among Endogens for netted-veined leaves. It consists both of herbs and of shrubby plants climbing by tendrils ; the perianth is free from the ovary ; the mostly three styles or sessile stigmas are entirely dis- tinct ; the anthers are introrse ; and the fruit is a berry. Embryo minute, in hard albumen. — In the True Smilax Family, the flowers are dioecious and axillary; the six divisions of the perianth are alike ; the anthers are one-celled, and the few seeds are orthotropous and pendulous. They are mostly shrubby and alternate-leaved ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS. 493 plants. Ex. Smilax (Greenbrier, &c.) ; far the most important species is S. officinalis of tropical America, the rootstocks of which are the officinal Sarsaparilla. 948. Subord. Trilliaceee {Trillium Family) consists of low herbs, with whorled leaves and per- fect flowers, which in the largest genus, Trillium, have a green calyx and a colored corolla; the anthers are two-celled ; the seeds anatropous and rather numerous. — The short rootstock of Trillium (Fig. 169), called Birthroot, has a place in the popular materia medica ; but it is doubtful if it really possesses any useful properties. 949. Ol*d. LiliaCGCE {Lily Family). Herbs, with the flower-stems springing from bulbs, tubers, or with fibrous or fascicled roots. Leaves simple, sheathing or clasping at the base, parallel-veined. Flowers regular, per- fect. Perianth colored, mostly of six parts, or six-cleft. Stamens six: anthers introrse. 1216 Ovary free, three-celled : the styles united into one. Fruit capsular or baccate, with several or numerous seeds in each cell. Albumen fleshy. — This large and widely diffused order comprises a great variety of forms : the Lily, Dog-tooth Violet, and Tulip represent one division ; the Tuberose, a second ; the Aloe and Yucca, a third ; the Hyacinth, the Onion, Leek, and Garlic (Allium), and the As- phodel, a fourth ; the Asparagus, Lily of the Valley, and Solomon's Seal, a fifth, which is nearly allied to the order Smilacerc. Acrid and often bitter principles prevail in the order, and are most concen- trated in the bulbs, &c, which abound in starchy or mucilaginous matter, and are often edible when cooked. Squills are the bulbs of Scilla maritima of the South of Europe. Aloes is the acrid and bitter inspissated juice of the succulent leaves of species of Aloe. The original Dragon's-blood Avas derived from the juice of the fa- mous Dragon-tree (Dracama Draco) of the East. — The leaves of Phormium tenax yield the New Zealand hemp, one of the FIG. 1245. A flower of Trillium erectum ; a front view. 1246. A diagram of the same. 42 494 ILLUSTRATIONS OF THE NATURAL ORDERS. strongest vegetable fibres known. Many are the ornaments of our gardens and conservatories. 950. Ord, MelanthaceSB {Colchicum Family). Herbs, with bulbs, corms, or fasciculated roots. Perianth regular, in a double series ; the sepals and petals either distinct, or united below into a tube. Stamens six, with extrorse anthers (except in Tofieldia and Pleea). Ovary free, three-celled, several-seeded : styles distinct. Albumen fleshy. The true Melanthaceae, or 951. Suboi'd. MelfintllieBB have a mostly septicidal capsule and a marcescent or persistent perianth. — Ex. Colchicum has a perianth with a long tube, arising from a subterranean ovary ; it is also re- markable for flowering in the autumn, when it is leafless, ripening its fruit and producing its leaves the following spring. In most of the order, the leaves of the perianth are uncombined ; as in Vera- trum ("White Hellebore), Helonias, &c. Acrid and drastic poison- ous plants, with more or less narcotic qualities ; chiefly due to a peculiar alkaloid principle, named Veratria, which is largely ex- FIG. 1247. Erythronium Americanum (Dog-tooth Violet, Adder's-tongue). 1248. The bulb. 1249. Perianth laid opeiij with the stamens. 1250. The Pistil. 1251. Cross-section of the capsule. ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS. 495 tracted from the seeds of Sabadilla, or Cebadilla; the produce of Schcenocaulon officinale, &c. of the Mexican Andes. The seeds and the corms of Colchicum are used in medicine. 952. Subord. UvularieS (Bellwort Family) has a few-seeded loculi- cidal capsule or berry, more or less united styles, and a deciduous perianth ; the stems from rootstocks. — Ex. Uvularia. 953. Ord. JuncaceSD {Rush Family). Herbaceous, mostly grass- like plants, often leafless ; the small glumaceous flowers in clusters, cymes, or heads. Perianth mostly dry, greenish or brownish, of six leaves (sepals and petals) in two series. Stamens six, or three : anthers introrse. Ovary free, three-celled, or one-celled from the placenta? not reaching the axis ; their styles united into one : stig- mas three. Capsule three-valved, few- or many-seeded. Albumen fleshy. — Ex. Juncus (Rush). 954. Ord. FoiltederiaCCSB (Pickerel-weed Family) comprises a few aquatic plants, with the flowers, either solitary or spicate, arising from a spathe or from a fissure of the petiole ; the six-cleft and colored perianth persistent and withei'ing, often adherent to the base of the three-celled ovary ; the stamens three, and inserted on the FIG. 1252. Colchicum autumnale ; a flowering plant. 1253. Perianth laid open. 1254. Pistil, with the long distinct styles. 1255. Leafy stem and fruit (capsule opening by septi- cidal dehiscence). 1256. Capsule divided transversely. 1257. Section of a seed, and a sep- arate embryo. 496 ILLUSTRATIONS OF THE NATURAL ORDERS. throat of the perianth, or six, and unequal in situation. Ovules anatropous, numerous ; hut the fruit often one-celled and one-seeded. — Ex. Pontederia (Pickerel-weed), Heteranthera, &c. 955. Ord. ComilielynaceiC {Spiderwort Family), with usually sheath- ing leaves ; distinguished from other Endogens (except Alismaceoe and Trillium) by the manifest distinction between the calyx and corolla ; the former of three herbaceous sepals ; the latter of as many delicate colored petals. Stamens six, or fewer : anthers with two separated cells : filaments often clothed with jointed hairs, hypogynous. Ovary two- or three-celled : styles united into one. Capsule few-seeded, loculicidal. Seeds orthotropous. Embryo small, pulley-shaped, partly sunk in the apex of the albumen. — Ex. Commelyna, Tradescantia (Spiderwort) Mucilaginous plants. 956. Ol'd. Xjl'idaceSB. Low, rush-like plants ; with ensiform, grassy or filiform radical leaves, sheathing the base of a simple scape, which bears a head of flowers at the apex, imbricated with bracts. Calyx of three glumaceous sepals, caducous. Petals three, with claws, more or less united into a monopctalous tube. Stamens six, inserted on the corolla ; three of them bearing extrorse anthers, the others mere sterile filaments. Ovary one-celled, with three parietal placentae, or three-celled : styles partly united : stigmas lobed. Capsule many-seeded. Seeds orthotropous, albuminous. — Ex. Xyris (Yellow-eyed Grass). 957. Ord. EriocaillonacetB {Pipewort Family). Aquatic or marsh herbs, with much the structure of the preceding ; their leaves cel- lular or fleshy ; their minute flowers (monoecious or dioecious) crowded, along with scales or hairs, into a very compact head : the corolla less petaloid than in Xyridacea? ; the six stamens often all perfect ; the ovules and seeds solitary in each cell. — Ex. Eriocaulon. 958. Ord. Restiaceae consists of South African and Australian Rush-like plants, with the aspect of Cyperaceae, but with one-celled anthers and orthoti'opous seeds. 959. Ol'd. CyperaeeSB {Sedge Family). Stems {culms) usually solid, casspitose. Sheaths of the leaves closed. Flowers one in the axil of each glumaceous bract. Perianth none, or a few bristles. Stamens mostly three, hypogynous. Styles two or three, more or less united. Fruit an achenium. Embryo small, at the extremity of the seed next the hilum. — Ex. Cyperus, Scirpus, Carex (Sedges). The herbage is little eaten by cattle. Some Clubrushes are used for making mats, chair-bottoms, &c. The papyrus of the Egyptians ENDOGENOUS OR MONOCOTYLEDONOUS PLANTS. 497 was made from the stems of Cyperus Papyrus. The tubers of C. esculentus are sweet and edible, but are too small to be of much value for food. 1262 960. Ol'd. GramilieSB ( Grass Family). Stems (culms) cylindrical, mostly hollow, and closed at the nodes. Sheaths of the leaves split or open. Flowers in little spikelets, consisting of two-ranked imbri- cated bracts ; of which the exterior are called glumes, and the two that immediately enclose each flWer, palece. Perianth none, or in the form of very small and membranous hypogynous scales, from one to three in number, distinct or united (termed squamulce, squa- mellce, or lodiculce). Stamens commonly three : anthers versatile. Styles or stigmas two ; the latter feathery. Fruit a caryopsis. Embryo situated on the outside of the farinaceous albumen, next the FIG. 1258. Scirpus triqueter, -with its cluster of spikelets. 1259. A separate flower, en- larged, showing its rudimentary perianth of a few denticulate bristles, its three stamens, and pistil with a three-cleft style : a, section of the seed, showing the minute embryo. 1260. Ca- rex Careyana, reduced in size (flowers monoecious, the two kinds in different spikes). 1261. Stem, with the staminate and upper pistillate spike, of the size of nature. 1262. A scale of the staminate spike, with the flower (consisting merely of three stamens) in its axil. 1263. Magnified pistillate flower, with its scale or bract : the ovary enclosed in a kind of sac (perigy- nium), formed by the union of two bractlets. 1264. Cross-section of the perigynium; with the pistil, p, removed. 1265. Vertical section of the achenium, showing the seed. 42* 498 ILLUSTRATIONS OF THE NATURAL ORDERS. hilum (Fig. 126-128, G22 - C24). — J5r. Agrostis, Phleum, Poa, Festuca, which are the principal meadow and pasture grasses : Ory- za (Rice), Zea (Maize), Avena (the Oat), Triticum (Wheat), Secale (Rye), Hordeum (Barley), are the chief cereal plants, cultivated for their farinaceous seeds. This universally diffused order is one of the largest of the vegetable kingdom, and doubtless the most impor- tant ; the floury albumen of the seeds and the nutritious herbage constituting the chief support of man and the herbivorous animals. No unwholesome properties are known in the family except in the grain of Darnel, which is deleterious. Ergot, or Spurred Rye, is no exception, being a morbid growth, caused by a parasitic fungus. The stems of grasses frequently contain sugar in considerable quan- tity (especially when they are solid) ; as in Maize, the sweet variety of Sorghum vulgare, or Broom-Corn, and in Sugar-Cane (Saccharum ofncinarum), which affords the principal supply of this article. 1271 1275 1278 1277 1278 FIG. 126G. One-flowered spikelet or loeusta of Alopecurus, with the glumes separated. 1267. Same, with the glumes removed : an awn on the back of the outer palea. 1268. One- flowered spikelet of an Agrostis. 1269. Pistil of a Grass, showing the two feathery stigmas, and the two hypogynous scales or squamuhe, larger than usual (representing the perianth). 1270. Two-flowered spikelet of an Avena ; with the glumes spreading. 1271. One of the flow- ers with its paleee ; the exterior pointed, with two bristles or cusps at the apex, and with a bent awn on the back. 1272. Many-flowered spikelet of Glyeeria fluitans. 1273. An enlarged separate flower of the same, seen from within, showing the inner palea;, &c. 1274. The fruit (caryopsis) of the Wheat, with an oblique section through the integuments of the embryo, which is exterior to the albumen. 1275. Detached magnified embryo : a, the imperfect cotyle- don ; b, the first leaf of the plumule; c, the second leaf of the plumule ; rf, the radicle. 1276. The caryopsis of Hordeum (Barley;. 1277. A cross-section. 1278. A vertical section, show- ing the external embryo at the base. 1279. Magnified detached embryo, with its broad cotyle- don and the plumule. 1280. More magnified vertical section of the same : a, the plumule ; b, the radicle. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 499 Series II. Cryptogamous or Flowerless Plants. Plants destitute of proper flowers (stamens and pistils), and propagated by spores instead of seeds. Class III. Acrogenous Plants.* Vegetables with a distinct axis, growing from the apex, with no provision for subsequent increase in diameter (containing woody and vascular tissue), and usually with distinct foliage. 9G1. Ol'd. EquisetacefC {Horsetail Family). Leafless plants ; with striated, jointed, simple or ]282 1231 branched stems (containing ducts and some spiral vessels), which are hollow and closed at the joints ; each joint terminating in a toothed sheath, which surrounds the base of the one above it. In- florescence consisting of peltate scales crowded in a terminal spike, or kind of strobile : each with several thecce attached to its lower surface, longitudinally de- hiscent. Spores numerous, with four elastic club-shaped bodies (of unknown use), wrapped around them when moist, or spreading when dry. — Ex. Equi- setum. The epidermis of Equi- setum hyemale (the well-known Scouring Rush) contains so much silex that it is used for polishing. * For illustrations of Classes III. and IV. see the plates of Manual of the Botany of the Northern United States. FIG. 1281. Summit of the stem of Equisetum sylvaticum. 1282. Part of the axis of the fructification, with some of the fruit-bearing organs, shown magnified in Fig. 1283, a view from underneath. 1284. A separate theca, or spore-case, more magnified. 1285, 12S6. Spores, with the club-shaped appendages more magnified. 500 ILLUSTRATIONS OF THE NATURAL ORDERS. 962. Ord. Filices (Ferns). Leafy plants ; with the leaves (fronds) spirally rolled up or circinate in vernation (except in one suborder), usually rising from prostrate or subterranean rootstocks, or in tree- Ferns from an erect arborescent trunk (Fig. 100), and bearing on the veins of their lower surface, or along the margins, the simple fructification, which consists of one-celled spore-cases (thecce or spo- rangia), opening in various ways, and discharging the numerous minute spores. The stalk or petiole of the frond is termed a stipe. — There are four principal suborders, viz. : — FIG. 1287. Camptosorus rhizophyllus (Walking Fern) ; the fronds rooting, as they fre- quently do, at the apex ; the sori occupying the reticulated veins on the back. 1238. Division (pinnula) of a frond of Aspidium Goldianum ; the roundish sori attached to the simple veins, and covered with an indusium, which is fastened in the centre, and opens all around the mar- gin. 1289. Magnified sporangium of this division of Ferns, with its stalk, and elastic ring partly surrounding it ; which, tending to straighten itself when dry, tears open the sporangium, shedding the minute spores (1290). 1291. Sehizsea pusilla of about the natural size, with simple and slender radical leaves ; the contracted fertile frond pinnate. 1292. A division (pinna) of the fertile frond, magnified, showing the sessile sporangia occupying its lower surface. 1293. One of the sporangia more magnified ; they have no proper ring, and open by a longitudinal cleft. 1294. Ophioglossum vulgatum (Adder's-tongue) ; the sporangia forming a two-ranked spike on a transformed and contracted frond : a, portion of the spike enlarged, showing the co- riaceous sporangia, destitute of a ring, and opening transversely. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 501 963. Subord, PolypodinCiT. Sporangia collected in dots, lines, or variously shaped clusters (sori or fruit-dots) on the hack or margins of the frond or its divisions, or rarely covering the whole surface, stalked, cellulai'-reticulated, the stalk running into a vertical incom- plete ring, which hy straightening at maturity ruptures the sporan- gium transversely on the inner side, discharging the spores. Fruit- dots often covered, at least when young, by a membrane called the involucre, or more properly the indusium. 964. Subord. Ilyilieiiophyllea:. Sporangia borne on a vein extended beyond the margin of the frond into a setiform receptacle, sessile, and surrounded by a horizontal complete ring ; otherwise as in the last. — Ex. Hymenophyllum, Trichomanes. Ferns of very delicate texture, chiefly tropical. 965. Subord. OsmillldineEC. Sporangia variously collected, cellular- reticulated, destitute of any ring (as in Osmunda or Flowering Fern), or with an imperfect trans- 1236 verse ring around the top (as in Schizrca, Fig. 1293), opening lengthwise by a regular slit. 966. Subord. Ophioglossesc. Spo- rangia spiked, closely sessile, naked, coriaceous and opaque, not reticu- lated, destitute of a ring, opening by a transverse slit into two valves, discharging the very copious spores Avhich appear like floury dust. Fronds straight, never rolled up (or circinate) in the bud ! 967. Ord. Lycopodiacea; (Club-3foss Family). Plants with creeping or erect leafy stems, mostly branching ; the crowded leaves lanceolate or subulate, one-nerved. Sporangia single and sessile in the axils of the leaves, sometimes all crowded m5 at the summit under leaves which are changed into bracts and form FIG. 1295. Lycopodium Carolinianum, of the natural size. 1296. A leaf from the spike of fructification, with the spore-case in its axil, and spores falling out. 1297. A group of four larger spores (oophoridia) of Selaginella, magnified. 1298. The same, separated. 1299. A burst spore-case of Selaginella apus, with its four large spores. 502 ILLUSTRATIONS OF THE NATURAL ORDERS. a kind of anient, one-celled, or rarely two- to three-celled, dehiscent, containing either minute grains, appearing like line powder, or a few rather large sporules ; both kinds often found in the same plant. — Ex. Lycopodium (Club-Moss, Ground Pine), Selaginella. — Append- ed to this family, rather than to the next (with which it has gener- ally been associated), is the 968. Suboi'd. Isoctilieae (Quillwort Family), consisting of a few acaulescent submersed aquatics, with their sporangia in the axils and immersed in the inflated base of the grassy subulate leaves. — Ex. Isoetes. 9G9. Ol'd. Ilydl'Opterides. Aquatic or marshy cryptogamous plants, of diverse habit, with the fructification borne at the bases of the leaves, or on submerged branches : this consists of two sorts of or- gans, contained in indehiscent or irregularly bursting involucres (sporocarps). It comprises the 970. Sllbord. Mai'SilaceOC (Pepperwort Family) ; with creeping stems ; the leaves long-stalked, circulate in vernation, and of four obcordate leaflets in Marsilea, or filiform and destitute of leaflets in Pilularia (the Pillwort). 971. Suboi'd. SalvinieSB ; which are free floating plants, with alter- nate and sometimes imbricated sessile leaves ; the fructification borne on the stem or branches underneath. — Ex. Salvinia, Azolla. (For illustrations, see Manual of Botany, Plate 14.) Class IV. Anophytes. Vegetables composed of parenchyma alone, with acrogenous growth, usually with distinct foliage, sometimes the stem and foliage confluent into a frond. 972. Ol'd. Musci {Mosses). Low, tufted plants, always with a stem and distinct (sessile) leaves, producing spore-cases which mostly open by a terminal lid, and contain innumerable simple spores. The fertilizing organs, or antheridia, have been elsewhere mentioned. In Mosses these accompany the pistillidia ; the latter develop into the capsule, or more properly the sporangium or spore-case. This is rarely (in Andraia) dehiscent into four valves, or irregularly rup- tured (in Phascum, &c). It usually opens by a lid {ppercidum) : beneath the lid and arising from the mouth of the capsule are com- monly either one or two rows of rigid processes (collectively the CRYPTOGAHOUS OK FLOWERLESS PLANTS. 503 peristome), which are always some multiple of four: those of the outer row are called teeth, of the inner, cilia. The spores which fill the cavity commonly appear like an impalpable greenish powder. The pedicel continued through the capsule forms the columella : en- larged under the capsule it sometimes forms an apophysis. The calyptra separating early at its base is carried up on the apex of the capsule ; if it splits on one side, it is hood-shaped or cuculliform, if not, it is mitre-shaped or mitriform. The particular structure of all our genera of Mosses, and of the following order, is illustrated in the plates of the Manual of the Botany of the Northern United States ; to which the student is referred for details. 973. Ofll. HepatiCfB {Liverworts). Frondose or Moss-like plants, of a loose cellular texture, usually procumbent and emitting rootlets from beneath ; the calyptra not separating from the base, but usually rupturing at the apex ; the sporangium or capsule not opening by a FIG. 1300. Mnium cuspidatum. 1301. The calyptra detached from the spore-case. 1302. Magnified spore-case, from which the lid or operculum, 1303, has been removed, showing the peristome. 1304. A portion of the annulus or ring under the lid, more magnified. 1305. A portion of the outer and inner peristome, highly magnified. 1306. The so-called flowers in a young state, consisting of the pistillidia $, and the antheridia -c.) are parasitic (150, 153) flowerless plants, either in a strict sense, as living upon and draw- ing their nourishment from living, though more commonly languish- ing, plants and animals, or else as appropriating the organized mat- ter of dead and decaying animal and vegetable bodies. Hence they fulfil an office in the economy of creation analogous to that of the infusory animalcules. Those Fungi which produce Rust, Smut, Mildew, &c. are of the first kind ; those which produce Dry-rot, &e. hold a somewhat intermediate place ; and Mushrooms, Puff-balls, &c. are examples of the second. Fungi are consequently not only destitute of anything like foliage, but also of the green matter, or chlorophyll, which appears to play an essential part in vegetable assimilation. A full account of the diversified modifications of struc- ture that Fungi display, and of the remarkable points in their economy, would require a large volume. We will notice three sorts only, which may represent the highest, and nearly the lowest, forms of this vast order or class of plants. They all begin (in germina- tion or by offsets) with the production of copious filamentous threads, or series of attenuated cells, appearing like the roots of the fungus that arises from them (Fig. 1328, 1330), and to a certain extent performing the functions of roots : this is called the mycelium, and is the true vegetation of Fungi. The subsequent developments properly belong to the fructification, or are analogous to tubers, rhizomas, &c. In one part of the order, the masses that arise, of various definite shapes, and often attaining a large size, contain in their interior a multitude of asci (Fig. 1329), enclosing simple or double sporules, just as in Lichens. The esculent Morel has this kind of fructification ; as well as the less conspicuous Sphaeria (Fig. 1328), which is in other respects of a lower grade. The Agarics, like the Edible Mushroom (Fig. 1330), produce their spores in a different way. Rounded tubercles appear on the mycelium ; some of these rapidly enlarge, burst an outer covering which is left at the base (the volva, or wrapper), and protrude a thick stalk (stipes), bearing at its summit a rounded body that soon expands into the pileus, or cap. The lamellce, or gills (Jtymenium), that occupy its lower surface, consist of parallel plates (Fig. 1331), which bear naked sporules over their whole surface. A careful inspection with the microscope shows that these sporules are grouped in fours ; and a view of a section of one of the gills shows their true origin (Fig. 1332). Certain of the cells (basidia), one of which is shown more 508 ILLUSTRATIONS OP THE NATURAL ORDERS. magnified at Fig. 1333, produce four small cells at their free sum- mit, apparently by gemmation and constriction : these are the spores. It is maintained that the larger intermingled cells, (of which one is shown at Fig. 1332, a,) filled with an attenuated form of matter, are the analogues of antheridia. The lowest Fungi produce from their mycelium only simple or branching series of cells (Fig. 92-94). The mycelium itself either ramifies through decaying organized matter, as the Moulds, &c. ; or else — like the Blight and Rust in grain, and the 3fuscardine so destructive to silkworms, and others so destructive to the Grape, the Potato, &c. — it attacks and spreads throughout living tissues, often producing great havoc before its fructification is revealed at the surface. Sometimes the last cells of the stalks swell into a vesicle, in which the minute sporules are formed ; as in Fig. 92. Sometimes the branching stalks bear single sporules, like a bunch of grapes (Fig. 94), or long series of cells, or FIG. 1328. Sphseria rosella. 1329. Asci from its interior, containing sporules, highly mag- nified. 1330. Agaricus campestris, the Edible mushroom, in its various stages. 1331. Section through the pileus, to display the gills. 1332. A small piece of a slice through the thick- ness of one of the gills, magnified ; showing the spores borue on the summit of salient cells of both surfaces. 1333. One of the sporule-bearing cells, with some subjacent tissue, more magnified. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 509 sporules, in rows, like the beads of a necklace (Fig. 93), which, separating, become the rudiments of new plants. 980. Ol'd. AlgSB (Seaioeeds). This vast order consists of aquatic plants, for the most part strictly so, but some grow in humid ter- restrial situations. The highest forms are the proper Seaweeds ( Wrack, Tang, Dulse, Tangle, &c.) ; " some of which have stems ex- ceeding in length (although not in diameter) the trunks of the tallest forest-trees, while others have leaves (fronds) which rival in expan- sion those of the Palm." " Others again are so minute as to be wholly invisible, except in masses, to the naked eye, and require the highest powers of our microscopes to ascertain their form and struc- ture." Some have the distinction of steins and fronds ; others show simple or branching solid stems only ; and others flat foliaceous ex- pansions alone (Fig. 95), either green, olive, or rose-red in hue. From these we descend by successive gradations to simple or branching series of cells placed end to end, such as the green Con- fervas of our pools, and many marine forms : we meet with congeries of such cells capable of spontaneous disarticulation, each joint of which becomes a new plant, so that the organs of vegetation and of fructification become at length perfectly identical, both reduced to mere cells ; and finally, as the last and lowest term of possible vege- tation, we have the plant reduced to a single cell, giving rise to new ones in its interior, each of which becomes an independent plant (Fig. 79 - 83, 18 - 22). Our Alga? should be studied by the aid of the admirable Nereis Boreali-Americana, or History of the Marine AlgcB of North America, by Professor Harvey, published by the Smithsonian Institution. For the fresh-water species we have no American work. The main divisions of Alga? are into the following suborders. 981. Subord. MelanospermCflB, or FucaceSE, the Olive-green Seaweeds; having dark-colored spores and generally an olive-green color, such as the common Rockweed, Gulfweed, &c. The fertilization of these spores has already been described (661). 982. Subord. Rliodosperiliere, or Floridefe, the Hose-red Seaioeeds, so called from their prevailing color. These, the most beautiful of Alga? (including the Dulse, Laver, &c.) have two kinds of spores ; one large, simple, and superficial ; the others dispersed through the interior of the frond, and formed four together in a mother cell. 983. Sllbord. Clllorospermerc, the Bright-green Alga;, the spores and the vegetation of which are generally of a lively green hue, are more 43* 510 ILLUSTRATIONS OF THE NATURAL ORDERS. simple in structure, and include the fresh-water kinds generally, as well as numerous marine species ; among them those of single rows of cells, or of single cells (100-105, 656 - 660). Some of these fruc- tify by conjugation (655 — 657), as is the case in those simplified forms which compose the 984. Sllbord. DcsmidiaceSB, which are microscopic and infusory green Alga3 of single cells (Fig. 100, 655), often of crystal-like forms, in- vested with mucus, and belonging to fresh water. They multiply largely by division, but strictly propagate only by conjugation. Many of them have long been claimed for the animal kingdom, or es- teemed of ambiguous nature, on account of the free movements they exhibit ; but this affords no real distinc- tion. (Chap. XII., XIII.) More ambiguous still, and on the lowest confines of the vegeta- ble kingdom, are those minute vegetables, as they doubtless are, which constitute the 985. Subord. Diatomaccrc. These differ from the last chiefly in the brown instead of green color of their contents, in the siliceous and durable nature of their cell-wall, and in being natives of salt instead of fresh water. Their movements, as they break up from their connections, are still more vivid and varied. Some are fixed ; others are free. Some are extremely minute : others form clusters of cells of considerable size. All require a compound microscope for their study, and a full treatise is needed to do them justice. 986. Ord. Characese. The Chara Family consists of a few aquatic plants, which have all the simplicity of the lower Algae in their vegetation, being composed of simple tubular cells placed end to end, and often with a set of smaller tubes applied to the surface of the main one (Fig. 1335, 1336). Hence they have been placed among Algae. But their fructification is of a higher order. It con- sists of two kinds of bodies (both shown in Fig. 1335), of which FIG. 1334. Branch of the common Chara, nearly the natural size. 1335 A portion magni- fied, showing the lateral tubes enclosing a large central one (a portion more magnified at 1336) ; also a spore, invested by a set of tubes twisted spirally around it ; and the antheridium borne at its base. THE ARTIFICIAL SYSTEM OF LINN.EUS. 511 the smaller (and lower) contains antheridia of curious structure, provided with slender and active spermatozoids, while the upper and larger is a sporocarp, formed of a budding cluster of leaves wrapped around a nucleus, which is a spore or sporangium. The order might perhaps have been introduced between the Equise- tacere (to which the verticillate branches show some analogy) and the Hydropterides ; but its true position is hard to determine. CHAPTER IV. OF THE ARTIFICIAL SYSTEM OF LINN.EUS. 987. The difference in principle between an artificial and a natu- ral system of classification has already been indicated (715). No one better understood this than Linnceus, when, finding it impossible in his day to make a natural classification available for ordinary use, he proposed, as a temporary substitute, the elegant artificial scheme which bears his name. As this system is identified with the history of the science, which in its time it so greatly promoted, and as most systematic works have until recently been arranged upon its plan, it is still necessary for the student to understand it. Its principles are so simple, that a brief space will amply suffice for its explanation. 988. It must be kept in mind, that an artificial scheme does not attempt to fulfil all the conditions of natural-history classification. Its principal object is to furnish an easy mode of ascertaining the names of plants ; their relationships being only so far expressed as the plan of the scheme admits. All higher considerations are of course sacrificed to facility. In the Linnsean classification, the species of a genus are always kept together, whether or not they all accord with the class or order under which they are placed. Its lower divisions, therefore, namely, the genera and species, are the same as in a natural system. But the genera are arranged in arti- ficial classes and orders, founded on some single technical character, and have no necessary agreement in any other respect ; just as words are alphabetically arranged in a dictionary, for the sake of convenience, although those which stand next each other have, it may be, nothing in common beyond the initial letter. 512 THE ARTIFICIAL SYSTEM OF LINNAEUS. 989. The classes and orders Linnaeus founded entirely upon the number, situation, and connection of the stamens and pistils ; the office and importance of which he had just set in a clear light. 990. The classes, twenty-four in number, were founded upon modifications of the stamens, and have names of Greek derivation expressive of their character. The first eleven comprise all plants with perfect flowers, and with a definite number of equal and un- connected stamens. They are distinguished by the absolute number of these organs, and are designated by names compounded of Greek numerals and the word andria (from uvrjp), which is used meta- phorically for stamen, as follows : — Class 1. Monandria includes all such plants with one stamen to the flower ; as in Hippuris. 2. Diandria, those with two stamens, as in the Lilac. 3. Triandria, with three stamens, as in the Valerian, &c. 4. Tetrandria, with four stamens, as in the Scabious. 5. Pentandria, with five stamens, the most frequent case. 6. Hexandria, with six stamens, as in the Lily Family, &c. 7. Heptandria, with seven stamens, as in Horsechestnut. 8. Octandria, with eight stamens, as in Evening Primrose, &c. 9. Enneandria, with nine stamens, as in the Rhubarb. 10. Decandria, with ten stamens, as in Rhododendron. 11. Dodec andria, with twelve stamens, as in Asarum and the Mignonette ; extended also to include those with from thirteen to nineteen stamens. 991. The two succeeding classes include plants with perfect flow- ers, having twenty or more unconnected stamens, which, in 12. Icosandria, are inserted on the calyx (perigynous, 467), as in the Rose Family ; and in 13. Polyandria, on the receptacle (hypogynous, 466), as in the Buttercup, Anemone, &c. 992. Their essential characters are not indicated by their names ; the former merely denoting that the stamens are twenty in number ; the latter, that they are numerous. — The two following depend upon the relative length of the stamens, namely, 14. Did yn ami a, including those with two long and two short stamens (Fig. 407) ; and 15. Tetrad ynamia, those with four long and two short sta- mens, as in Cruciferous flowers (Fig. 406). THE ARTIFICIAL SYSTEM OF LINN^US. 513 998. Their names ai'e Greek derivatives, signifying in the former that two stamens, and in the latter that four stamens, are most pow- erful. — The four succeeding are founded on the connection of the stamens: — 16. Monadelpiha (meaning a single fraternity), with the filaments united in a single set, tube, or column, as in all the Mallow Family, &c. 17. Diadelphia (two fraternities), with the filaments united in two sets or parcels. 18. Polyadelphia (many fraternities), with the filaments united in more than two sets or parcels. 19. Syngenesia (from Greek Avords signifying to grow to- gether), with the anthers united in a ring or tube, as in all Compositaj (844). 994. The next class, as its name denotes, is founded on the union of the stamens to the style : — 20. Gynandria, with the stamens and styles consolidated, as in the Orchis Family (Fig. 468). 995. In the three following classes, the stamens and pistils are found in separate blossoms : — 21. Moncecia (one household) includes all plants where the stamens and pistils are in separate flowers on the same individual ; as in the Oak, &c. 22. Diozcia (two households), where they occupy separate flowers on different individuals ; as in the Willow, Pop- lar, Moonseed (Fig. 413, 414), &c. 23. Polygamia, where the stamens and pistils are separate in some flowers and united in others, either on the same, or two or three different plants ; as in most Maples. 996. The only remaining class, 24. Cryptogamia, is inferred to have concealed stamens and pistils (as the name imports), or the analogues of these organs, and includes the Ferns, Mosses, Lichens, &c., which are now commonly termed Cryptogamous or Flow- erless Plants (651). 997. The characters of the classes may be presented at a single view, as in the subjoined analysis : — 514 THE ARTIFICIAL SYSTEM OF LINN.EUS. w H O w S> H] o M H O ; OS Pi ; ft ft : «' h ! H R i W M CH ftlt j3 2 « ; cS ft i S5 5 o < IhPh P 6-1 (*sa ft, oa O o rH c-i co 3 jy )C3 o o g c<5 fo M a o o 9 w ^J "^ a a w to d • S 3 II ft ,-, 2 h£ a a a . o o • ci s a Iff g 1 o o ■0*2 S 3 s-a HNM-^IOCDNOOOIOHOH g* JS.3.2 a rHrilNN tfttfttn a 3 §1 hhhh >>-,>>>> oj.ft ft-3 »5 -v a c-§3^" a a th tain •urn 2 o ■a" W MlM I "3 o ta 9 03 .2 ft. '3. § ■^ ; a C3 5 «- a s -^ logue in Mosses of the pistil. Arcuate : curved like a bent bow. Areola, pi. areolae : spaces marked out on a surface. Are'olate: marked out into definite spaces. Arhizal : destitute of root Aril, arillus : an accessory covering or appendage of a seed formed by a growth from the funiculus, hilum, or placenta after the completion of , the ovule, 321, fig. 603. Arillate : furnished with an arillus. Arillode : a false aril, or covering of the seed appearing like an aril. Aristate : furnished with an awn (arista). Aristoloehiaceas, 462. Arnatto, 392. Arre'ct : pointing upwards. Arrowroot, 481, 490. Arrow-shaped, or arrow-headed : see Sa- gittate ; fig. 252. Artichokes, 437. Articulated: jointed, i. e. separating by an articulation or joint, as most leaves from the stem in autumn, or having the appearance of a joint, 92, 163, 173. Artificial classification, 365, 511. Artocarpese, 474. Ascending : rising obliquely upwards, 102. Ascending axis, 72, 91. Asci: the spore-cases of certain Lichens and Fungi, 506, 507. Ascidium : a pitcher-shaped or sac- shaped leaf, 169. Asclepiadaceae, 458. Ashes of plants, 58, 174, 186. Aspergilliform : shaped like an aspergil- lus, or brush used to sprinkle holy water, as the stigmas of most Grasses. Assafcetida, 427. Assimilation, 19, 21, 61, 177, 190. Assurgent : same as ascending. Atropous or dtropal (ovules) : same as orthotropous, 298. Attar of Koses, 417. Attenuate : tapering gradually to a thin or narrow extremity. Augmentation of parts, 242. Aurantiaceoe, 401. Auriculate : eared ; furnished with au- ricles or small lobes at the base. Automatic movements, 347. Ava, 469. Avocado Pear, 467. Awl-shaped: narrow and terete, or near- ly so, and tapering to a point ; 166. Awn : a bristle-shaped appendage, like the beard of Barley, &c. Awned : see Aristate. Axil {axilla, the armpit) : the angle be- tween a leaf and the stem, on the upper side, 97. Axile, or axial : belonging to the axis, , 292. Axillary : belonging to or growing in the axil. Axillary buds, &c, 97, 210. Axis : the stem and root, 67, 72 ; the central line of any body, as the Axis of inflorescence, 211. Baccate : berry-like ; of a fleshy or pulpy texture like a berry (bacca), 311. Balm of Gilead, &c, 407. Balsams, 145, 407, 414, 480. Balsamiflua?, 425. Balsaminaceai, 403. Banner : same as vexillum, 253. Barbate : bearded ; bearing tufts, spots, or lines of hairs. Bdrbellate : beset with short and stiff hairs, like the pappus of Liatris spicata, &c. Barbe'llulate : a diminutive of the last. Barberry, 384. Bark, 120, 126. Barley, 498. Basal : belonging or relating to the base of an organ. Basellacese, 464. Basidia : cells of the fructification of Mushrooms, &c, which bear the spores, 507. Bdsiflxed : attached by the base. Basilar : seated on the base of anything. Bassorin, 55. Bast, or bass, 400 : bast-cells or tissue, 44, 120. Bauerieaa, 425. Bavberry, 477. Bdellium, 407. GLOSSARY AND LNDEX. 525 Beaked : ending in a prolonged narrow tip. Bearded: beset with hairs, especially stiff or long hairs. Beard is some- times used for awn. Bell-shaped : having the shape of a bell ; 277, fig. 456. Benzoic Acid, Benzoin, 443. Berberidaceaj, 384. Bergamot, 401. Berry : a fruit fleshy or pulpy through- out, 311. Betel, 469. Betulaceae, 477. Bi- (or bis), as a prefix, means twice, as in the following : Biaciiminate : two-pointed. Biarticidate : two-jointed. Biauriculate : two-eared. Bibrdeteate : with two bracts. Bibrdcteolate : with two bractlets. Bicdllose : bearing two callosities or lit- tle protuberances. Bicipital : having two stalks or legs, as the keel of a papilionaceous corolla, fig. 392. Bicdnjugate : twice-pahed, as when the petiole of a compound leaf forks twice. Bicomute : two-horned. Bide'ntate : having two teeth (not twice dentate or doubly toothed). Biennial: lasting more than one year, but not more than two years, 83. Bifai-ious : two-ranked ; arranged in two vertical rows. Bifid : two-cleft to the middle or there- abouts, 159. Biflorous : two-flowered. Bifdliate : two-leaved. Bifdliolate : of two leaflets. Bifurcate : two-forked, or, sometimes, twice-forked. Bigeminate : twice-paired. Bigener : a hybrid between two plants of different genera. Bignoniacese, 447. Bijugate : a pinnate leaf with two pairs of leaflets. Bilabiate: two-lipped, 255, 258, 278. Bildmellate, or bildmellar : of two plates or lamella;. Bilberry, 439. Bildbate, or bilobed: two-lobed, 159. Bildcular : two-celled. Binary : the parts in twos, 239. Binate : in twos ; produced or borne in pairs, 164. Binomial nomenclature (of two names), 363. Bipartite : two-parted. Bipinnate : doubly or twice pinnate ; 164, fig. 282. Bipinnately : twice pinnately, 161. Bipinndtijid: doubly or twice pinnati- fid; 161,fig. 280- Bipinndtisect : twice-pinnately divided, 161. Biplicate : twice folded, or having two folds. Bipdrose : opening by two small holes or pores, fig. 474. Biradiate : consisting of two rays. Birdlime, 469. Birimose : opening by two slits, as do most anthers, fig. 473. Bise'ptate: having two partitions. Bise'rial, or bise'riate : occupying two rows, one within or above the other. Biserrate : doubly serrate, i. e. the teeth themselves serrate. Bisexual : having both stamens and pis- tils, 261. Bisulcate : having two furrows. Bite'rnate : twice ternate ; i. e. divided into three parts, and these again into three ; 164, fig. 284. Blackberry, 416. Bladdery : thin and inflated, like a blad- der. Blade of a leaf, petal, &c, 145, 276. Bloom, 56, 144. Blueberry, 439. Boat-shaped: concave within and con- vex (and often keeled) without. Bohon-Upas, 475. Borraginacea?, 450. Bothre'nchyma , 45, 46. Brdchiate : with opposite branches, the successive pairs spreading at right angles with each other. Bract (Latin, bractea) : the leaves of an inflorescence, especially the leaf which subtends a flower, 143, 211. Brdcteate : subtended by a bract. Brdcteolate : subtended by Bractlets, brdc.teoles (Latin, bracteolos) : bracts of a second order, &c, or bracts on the pedicel or the flower- stalk, 211. Branches, and brancMets, 97. Brazil-wood, 414. Bread-fruit, 475. Breathing-pores, 52, 150. Bristles: stiff short hairs (52), or hair- like bodies. Bristly : beset with stiff bristles. Bromeliacea?, 492. Bryology : same as Muscology. Buckwheat, 466. Bud : a stem or branch in an undevel- oped state, 93. Budding, 100. Bud-scales, 95, 167. Buffalo-berry, 468. 526 GLOSSARY AND INDEX. Bulb: a permanent bud with fleshy scales, mostly subterranean, 109. Bulbiferous : producing bulbs. Bulb'lets : little bulbs above ground, 109. Bulbose, or bulbous : bulb-like in shape. Bulbo-tuber : same as a corm. Bullate : a surface appearing as if blis- tered, puckered, or bladdery (from bulla, a bubble). Burmanniacese, 490. Burseracere, 406. Bursiculate : provided with pouch-like appendages (bursiculte). Butomacere, 487. Butterfly-shaped corolla, 253, 277. Butternut, 476. Byssaceous : composed of fine entangled threads (byssus, or fine flax). Byttneriaceas, 398. Cabombacea?, 386. Cactacete, 421. Caducous: falling off at the time of expansion, as the calyx of the Poppy, 279. Csesalpinea;, 413. Ccesious : lavender-colored. Ccespitose, or cespitose : growing in tufts or turfs. Cajeput oil, 418. Calabash, 447. Calabash-Nutmeg, 383. Calat/ridium : a name for the head of Composite. Caldthiform : cup-shaped. Cdlcarate : bearing a spur (calcar), 278 ; as the Violet, fig. 396, and Lark- spur, fig. 398. Cdlceolate, or cdlciform, slipper-shaped. Callitrichacese, 470. Callose : furnished with callosities (calli) or hardened or protuberant spots. Calvous : bald. Calycanthaceae, 417. Cd/ycine : relating to the calyx. Calyculate, or caliculate : furnished with an outer accessory calyx (calyculus), or set of bractlets resembling a ca- lyx, as in Dianthus. Cahjptra : the hood or veil of the spore- case of a Moss, 503, 504 ; or a body like it, 389. Cahjptrate : furnished with a calyptra, or something like it. Cahjptriform : shaped like a calyptra or candle-extinguisher, as the calyx of Eschscholtzia, p. 389, fig. 692. Calyx : the exterior floral envelope, or leaves of the flower, 222, 274. Cambium, Cambium-layer, 122. Camelliaceaj, 400. Campanulacece, 438. Campdmdate : bell-shaped ; 277, fig. 456. Camphor, 400, 467. Campylospe'rmous : wlien a seed or seed- like fruit is rolled up so as to form a longitudinal furrow down one side, as that of Sweet Cicely. Campyldtropous or campyldtropal ovule or seed, 298, 299, fig. 527. Canada Balsam, 480. Canaliculate : longitudinally channelled. Cdncellate: resembling lattice- work. Candleberry, 477. Canescent: whitened or hoary with fine and close pubescence. Cannabineas, 475. Cannacese, 490. Caoutchouc, 57, 458, 473, 475. Capers, 391. Capillary, or capilldceous : hair-like. Capitate : headed ; having a globular apex like the head of a pin ; or col- lected into a head. Capitel/ate : diminutive of capitate. Capitidum : a head of flowers, as of Clover, Button-bush, &c. ; 213, fig. 320. Capparidacea?, 391. Capre'olate : furnished with tendrils. Caprifoliacese, 431. Capsular : relating to a Capsule : any compound dehiscent fruit ; 315, fig. 582, 583. Cardamon, 490. Carina : a keel ; the two anterior petals of a papilionaceous flower ; 254, fig. 392, c. Cdrinate: keeled ; furnished with a pro- jecting longitudinal ridge along the under side. Cariopsis, or carydpsis : a grain, 314. Cameous : flesh-colored. Carnose : fleshy in texture. Carpel (carpel lum or carpidium) : a sim- ple pistil, or one of the elements of a compound one, 290. Cdrpellary : pertaining to a carpel. Carpolocjy : the department of Botany that relates to fruits. Carpophore : the stalk of a pistil, 267. Carrot, 426. Cartilaginous : tough, like cartilage. Cdruncle : an excrescence at the hilum of certain seeds, 322. Carunculate : furnished with a caruncle. Caryophyllacea?, 395. Caryophyllaceous (corolla) : pink-like, 276. Carydpsis : a grain, 314. Caseine, 198. Cashew, 406. Cassava, 472. GLOSSARY AND INDEX. 527 Cassia-bark, 467. Castor-oil, 472. Castrate (stamen) : with no anther or one containing no pollen. Catapetalous : where the petals are unit- ed with each other at the base and with the base of the stamens, as in the Mallow family. Catechu, 414. Cate'nulate : composed of parts united end to end, like the links of a chain. Catkin: see Anient, 213. Caudate : tailed or tail-pointed. Caudex, 101. Caudicle : a little stalk, like that of the pollen-mass of Orchis, &c., fig. 1235 Caulescent : obviously having a stem. Caulicle : a little stem, or a rudimentary stem ; the radicle, 71. Cauline, or caulinar: relating to a Caulis : the main stem, 91. Cayenne pepper, 456. Cedrelacece, 401. Cedron, 405. Celastracese, 408. Cell : a cavity of an anther, ovary, &c., 281, 291. In vegetable anatomy, one of the vesicles, or elements of which a plant is composed, 23. Cell-formation, 27. Cell-growth, 30. Cell-multiplication, 28. Cellular bark, or envelope, 121. Cellular Plants, 68. Cellular tissue, or structure, 23. Cellule: same as Cell (in veg. anatomy). Cellulose, 27, 192. Celtidea?, 474. Centrifugal inflorescence, 218. " radicle, 326. Centripetal inflorescence, 212. " radicle, 326. Ceratophyllaceae, 470. Cereal : belonging to corn or corn- plants ; these having been called the gift of Ceres. Cernuous : nodding. Chaff: the scales or bracts on the re- ceptacle which subtend each a flow- er in the heads of many Composite, as the Sunflower; also the glumes, &c. of Grasses ; 215, 435. Chaffy : provided with, or of the texture of chaff". Chaldza : the part of the ovule where the coats, nucleus, &c. are all unit- ed; 298, fig. 521, d, 526, c. Channelled: see Canaliculate. Characeai, 510. Characters : the essential marks distin- guishing one species, genus, &c. from those most resembling it, 362. Chartaceous : of the texture of paper or parchment. Chcckerberry, 441. Chenopodiacea;, 464. Cherry, 417. Chestnut, 477. Chldrophyll : leaf-green, 58. Chlorosis : a loss of color ; a reversion of the petals, &c. of a blossom to green leaves. Chlorospermeae, 509. Chocolate, 398. Chdrisis : the division of one organ into two or more, 243. Chromule: the coloring matter of plants, especially of petals, &c. Chrysobalanacece, 415. Cicatrix : a scar left by the fall of a leaf or other organ. Cilia (sing, cilium, the eyelash) : hairs or bristles fringing the margin of any- thing ; those of the inner peristome of a Moss, 502. Ciliate : the margin fringed with hairs. Cinchona, 432. Cinchoneae, 432. Cinenchyina, 49. Cinereous, cineraceous : ash-gray. Cinnamon, 467. Circinate: involute from the top; 144, fig. 219. Circulation in cells, 31, 178. Circumcissile, or circumscissile : opening or divided by a transverse circular line; 317, fig. 588. Circumscription : the general outline. Cirrhose, cirrhiferous : tendril-bearing, or with organs serving as a Cirrhus : a tendril. Cistaceas, 393. Cistdma : a kind of sac lining the cham- ber under a stomate in certain plants. Classes, 360. Classification, 352. Clathrate : latticed. Clavate, claviform : club-shaped; narrow below and thickened towards the summit. Claviculate : with tendrils, or leafstalks acting as such (clavicular). Claiv: the narrowed base of a petal, &c, 276. Cleft : cut to about the middle, and with narrow or acute sinuses ; 159, fig. 261, 265. Climbing : rising by laying hold of oth- er objects in any way, 102. Clindnthium : the receptacle of the flow- ers in Composite. Cloves, 418. Club-shaped: see Clavate. 528 GLOSSARY AND INDEX. Clusiaceie, 400. Clustered : collected into a bunch. Clypeate : buckler-shaped. Coacervate : heaped together. Coddunate : cohering ; united at the base or farther. Coalescence, 249. Coalescent : growing together. Coarctute : crowded together. Coated : composed of layers ; or fur- nished with a rind. Cobwehbed, or cobwebby : bearing long hairs, like cobweb or gossamer. Cocculus Indicus, 384. Coccus (pi. cocci) : anciently a berry; now used for the closed carpels into which many fruits split (316), as those of Euphorbia, fig. 1143, 1 145, and Verbena, fig. 985. Cochledriform: shaped like a spoon (coch- lear). Cocldeate : like a snail-shell (cochlea). Cocoa-plum, 415. Cielospe'rmous : i. e. hollow-seeded ; the top and bottom incurved, as in Co- riander-seed. Coffee, 433. Coherent : united together. Cohesion of parts, 250, &c. Coleorhiza (root-sheath) : the sheath or covering (belonging to the cotyle- don or plumule) through which the radicle of most Endogens bursts in germination. Collar, collum : the neck or line of junc- tion between the primary stem and root. Collective fruits, 318. Coloeynth, 423. Colored: of some other color than green. Columbo-root, 384, 457. Columella : the axis, or central column, of a pod or spore-case. Column : the united filaments of mon- adelphous stamens, or the united filaments and style in gynandrous flowers; 281, fig. 468. Columnar : pillar-shaped. Coma : a tuft of any sort, especially a tuft of hairs on a seed, 321, fig. 602 ; the whole head of a tree, &c. Comate, or comose : bearing a coma. Combrctacca?, 419. Commelynacea;, or Commelinaceae, 496. Commissure : the line of junction of two carpels ; used mostly in Umbel- liferas, 426. Common: used as "general," opposed to partial. Cdmplanate : flattened. Complete flower : having all the kinds of organs, 222, 238. Complicate : folded upon itself. Compositai, 435. Compound flower, 215, fig. 323-325, and 435, fig. 887, &c. Compound leaf: one composed of two or more blades, 1 63. Compound pistil, 290. Compound spike, raceme, umbel, &c, 216. Compressed : flattened on two opposite sides. Concentric layers of wood, 112, 123. Conchiform : shell-shaped. Concolored : all of one color. Conduplicate ; folded together length- wise, 144, 165. Cone: see Strobile, 319. Conferruminate : stuck together by their adjacent faces, as the cotyledons of Ilorsechestnut, 327. Confcrted: crowded. Confluent : running together, or blended into one. Conformed : similar to ; or closely fitted to, as the skin to the kernel of a seed. Congested : crowded together. Conglobate: clustered into a ball. Conglomerate : thickly clustered. Coniferas, 479. Coniferous: cone-bearing. Conjugate : coupled; in single pairs. Conjugation, 332. Connate: united or grown together from the earliest state, 251. Connate-perfoliate, 166, fig. 294. Connective, connectivum : the part of the anther connecting its two cells or lobes, 281, 282. Connivent : converging. Conoidal: approaching a conical form. Consolidated: when unlike parts are grown together. Consolidation, 250. Continuous : not interrupted. Contorted: twisted, 272. Contortuplicate : twisted and folded. Contracted : either narrowed or short- ened. Contrary : opposite in direction to some- thing it is compared with, as the pod of Shepherd's Purse flattened contrary to the partition. Convolute (rolled up) or cdnvolutive aesti- vation, 272. Convolute vernation : rolled up length- wise in the bud, 144. Convolvulaeeze, 454. Copaiva, 414. Copal, 414. Copalche-bark, 434. Cordate : heart-shaped ; shaped like a heart as painted upon cards, the GLOSSARY AND INDEX. 529 sinus, or notched end, being at the base ; fig. 244. Cordiaceae, 451. Coriaceous : of a leathery consistence. Cork, 477. Corky : of the texture of cork. Corky envelope or layer of the bark, 121, 127. Conn (cormus) : a solid bulb, 108. Cormophytes : plants having an axis (root and stem), in contradistinc- tion to Thallophytes, 371 Cornacese, 428. Corneous: of the consistence of horn. Corniculate: furnished with a small horn. Cornine, 428. Cormtte: furnished with a horn (eormi). Corolla : the inner of the two floral en- velopes, 222, 275. Corol/dceous, cdrolline : like a corolla in appearance or texture, or belong- ing to the corolla. Cortina : a crown, such as the append- age at the top of the claw of the petals of Silene ; 246, fig. 378. Coronate : bearing a crown. Cortex : the bark or rind. Cortical: pertaining to the bark. Corticate : furnished with a distinct rind. Corymb : a convex or flat-topped flower- cluster, 211. Ctirymbose: disposed in, or resembling, corymbs. Costa : a rib, or midrib. Costate : ribbed, or with a midrib. Cotton, 44, 398. Cotyle'dons : the first leaves of the em- bryo ; seed-leaves, 71, 324. Cotyliform : dish-shaped. Coumarin, 414. Cowitch, 415. Cranberry, 439. Crassulaeeas, 423. Crate'riform : goblet-shaped. Creeping : running on or beneath the ground and rooting, 102. Cremocurp : the fruit of Umbelliferoe, 425. Crenate, or crenellcd: the margin fur- nished with even and rounded notches or scallops ; 159, fig. 256. Cre'nulate : diminutive of Crenate. Crescentieae, 447. Crested: see Cristate. Cribrose : pierced with holes like a sieve. Crinite : bearded with long hairs. Crispate : curled. Cristate : crested ; bearing any elevated appendage on its surface. Cross-breeds : individuals originated by 45 fertilizing one variety or species bv another, 356, 357. Crowberry, 474. Crown (246, 279, fig. 378) : see Corona. Crowned: see Coronate. Crowning : borne on the apex of any organ. Cruciate, or cruciform : cross-shaped, 277, as the corolla of the Mustard family, fig. 405. Cruciferse, 389. Crude sap, 53, 190. Crustaceous : crusty in texture, hard and brittle. Cryptogamia, 513. Cryptogamous or cryptogenic : relat- ing to Cryptogamous Plants, 69, 330, 499. Crystals, 59. Cucullate, or cuculliform : hooded or hood-shaped ; rolled up like a cor- net of paper, 503. Cucumber, 423. Cucurbitacese, 423. Culm: a straw, or straw-like stem, 101. Cultrate: shaped like a broad knife- blade. Ciineale, or cuneiform : wedge-shaped ; broad above, and narrowed to the base, with straight sides ; fig. 235. Cunoniacea?, or Cuuonieaj, 525. Cupressinese, 480. Cup-shaped, cupuliform : hemispherical, and hollow above. Cupulate : furnished with a Cupule, or cupula : the acorn-eup, 314. Cupulifera?, 476. Curled: irregularly folded and crimped. Currant, 421. Curvinerved, 158, fig. 236. Curvi serial : in curved ranks, 141. Cuscutea?, or Cuscutinea?, 455. Cushion : the swollen base of a leaf- stalk, or the enlargement below the insertion of many leaves. Cuspidate : tipped with a cusp, or sharp and rigid point ; 162, fig. 275. Custard-Apple, 382. Cut : see Incised, or Dissected. Cuticle : the outer skin or pellicle of the epidermis, 149. Cydthiform : cup-shaped. Cycadacese, 481. Cycle : one complete turn of a spire ; a circle. Cyclical : coiled into a full circle. Cyc/tisis : circulation in cells, 31. Cyl indraceous : approaching to the Cylindrical: circular in transverse out- line and tapering gradually, if at all, as in most stems. Cymbccform : boat-shaped. 530 GLOSSARY AND INDEX. Cyme (cyma) : a cluster of centrifugal inflorescences, 218. Ci/mose : bearing cymes, or cyme-like. Cymule (cymula) : a cymelet, or little cyme, 218. Cynarrhodium : such a fruit as that of Hose (fig. 429) and Calycanthus, fig. 815,819. CyperacesB, 496. Cypsela : an achenium with an adher- ent calyx-tube, as in Composite. Cystidium : a utricle. Cystoliih.es, 60. Cytoblast: the nucleus of a vegetable cell. Dammcr Pitch, 400. Deca-, in words of Greek derivation : ten ; as in Decagy'nia, 515. Decdgynous : with ten pistils or styles. Decdmerous : the parts in tens, 234. Decandria, 512. Decandrous : with ten stamens, 280. Decape'talous : with ten petals, 276. Deciduous : falling off, or subject to fall ; as petals falling after blos- soming, 279, and leaves before winter, 172. Declinate, declined: turned to one side. Decompound: several times compound- ed, 165. Decumbent : reclined on the ground, the summit rising, 102. Decurrent: prolonged below the inser- tion, as the leaves of the Thistle, 170. Decussate : the successive pairs crossing each other at right angles, 142. Deduplication (dedoublement) , 243. Definite : of a fixed number, and not above twelve or twenty. Definite growth, 100. Definite inflorescence, 217. Deflexed : bent downwards. Dfldrate : past the flowering state. Defoliate : having cast its leaves. Dehiscent fruits, &c, 315 ; opening by Dehiscence : splitting, as do pods,3 11,316. " of anthers, 283. Deliquescent : the stem dissolving into branches, 99. Deltoid: shaped like the Greek capital A. Demersed: growing under water. Dendroid, dendritic : tree-like. Dentate : same as toothed ; 159, fig. 255. Denticulate : furnished with fine teeth, or denticulations. Denudate : made naked. Depauperate : dwarfed in size. Depressed: flattened vertically or from above. Descending : tending gradually down- wards. Descending axis, 72, 79. Dcsmiduc, or Dcsmidiaccce, 510. Determinate inflorescence, 217. Descriptive Botany, 15. Development, 19. Dextrine, 54, 193. Dextrorse : towards the right. Di-, in Greek compounds ; two. Diadelphia, 513. Diade'lphous : stamens united by their filaments in two sets ; 280, fig. 40 1. Diandria, 512. Didndrous : with two stamens, 279. Diagnosis : a brief essential character. Dialype'talous : of distinct petals. Diapensiaccas, 454. Diaphanous : transparent. Diatomacese, 510. Dicdrpellary : of two carpels. Dichlamydeous : with both calyx and corolla. Dichondrcae, 455. Dichdlomous : forking into two branches. Diclinous : with the stamens and pistils in separate blossoms, 261. Dicdccous : separable into two cocci. Dicotyledonous : having a pair of cotyle- dons, 78, 326. Dicotyledons, Dicotyledonous Plants, 114,326,370. Didymous : twin. Didynamia, 512. Didynamous : with two long and two shorter stamens, 258, 281. Difformed: of unusual shape. Diffuse: widely and loosely spreading. Digamous : having flowers of two dif- ferent sexes. Digestion, 190. Digitate (fingered) : compound, with the parts all arising from the same point ; 163, fig. 277. Digitately tri-plurifoliolate, 164. Digynia, 515. Digynous : with two pistils or styles, 287. Di'lieniaceas, 380. Dimerous : the parts in twos, 234, 239. Dimidiate: halved, or appearing as if one half or side were wanting, 283. Dimdrphous : of two forms. Dicecia, 513. Diacious : with stamens and pistils in separate blossoms on different individuals, 262. Dioscoreaceas, 492. Diosmeos, 407. Dipetalous : of two petals, 276. Diphyllous : two-leaved, 275. Diploste'monous : stamens double the petals or sepals in number. GLOSSARY AND INDEX. 531 Dipsaceae, 435. Dipterocarpeas, 400. Dipterous : two-winged. Disciform: disk-shape; flat and circu- lar, like a disk or quoit. Discoidal, discoid : like a disk ; or be- longing to the disk ; destitute of rays, 436. Dise'palous • of two sepals. Disk, or disc: a fleshy expansion of the receptacle of a flower, 267 : the central part of a head of flowers, as opposed to the border, 436 ; the face of any flat body, as opposed to the margins. Disk-bearing woody tissue, 43. Disk-flowers, 436. Dissected : cut into pieces, or nearly so. Disse'piment : the partition of a pod, 291. Dissident : bursting in pieces. Distichous: in two vertical ranks, 134. Distinct : when parts of the same name are unconnected, 251. Divaricate : straddling widely. Divergent : separating, their summits inclining from each other. Divided: cut into distinct portions; 160, fig. 263, 267. Dodeca- : in Greek derivatives ; twelve. Dodecagynia, 515. Dodecdgynous : with twelve pistils or styles. Dodecandria, 512. Dodecdndrous : with twelve (or from twelve to nineteen) stamens, 280. Doldbriform : axe-shaped. Dorsal : belonging to the back (dorsum). Dorsal suture, 289. Dotted ducts, 38. Dotted leaves, &c. : marked with small spots, either colored, or transparent and appearing like punctures. Double flowers : monstrous blossoms, with the petals unduly multiplied, 222 229. Douhhj compound, 164. Downy : clothed with soft pubescence. Dragon's blood, 414, 493. Droseraeea?, 394. Drupaceous : like or pertaining to a Drupe: a stone-fruit, 312. Drupelet: a diminutive drupe, 313. Dryadese, 418. Ducts, 45. Dumose: bushy. Duplicate : doubled or folded. Duramen: heart-wood, 126. Dwarf: comparatively low in stature. E-, or Ex-, as a prefix, means destitute of ; as, ecostate, riblcss ; exalbumi- nous, without albumen, &c. Eared: see Auriculate. Earthy constituents of plants, 179, 186. Ebenaceae, 442. Ebe'neous : black like ebony. Ebony, 442. Ebrdcteale : destitute of bracts. Ebrdcteolate : destitute of bractlets. Eburncous : white like ivory. Ecldnate: beset with prickles (like a hedgehog). Echimdate : rough with small prickles. Ede'ntate : toothless. Ejffete: past the perfect or productive state. Effuse : very loosely spreading. Efjlandulose : destitute of glands. Elaborated sap, 53. Elasagnaceas, 467. Elaters, 40, 505. Elatinaceee, 395. Elementary constituents of plants, 179. Elementary structure of plants, 17. Ellipsoidal : approaching the form of Elliptical: oval or oblong, and witli both ends similar and regularly rounded. Eman/inate: notched at the end ; 162, fig. 273. Embracing : surrounding, as by abroad . attachment. Embryo: the rudimentary plantlet in a seed, 71,323. Emliryo-sac, 304. Embryogenij : the formation of the em- bryo, 304. Embryonal vesicle, 306. Emersed : raised out of water. Emetine, 433. Enantiobldstous : with the embryo at the end of the (orthotropous) seed dia- metrically opposite the hilum, as in Tradescantia. Endecagynia, 515. Endecdgynous : with eleven pistils or , styles. Endocarp : the inner laver of a pericarp, , 310, 312. Endochrome : the coloring matter of , Alga;. Endopen, Endocenae, Endogenous Plants, 113, 370, 482. Endogenous structure, 113, 114. Endophldum : inner bark, 120. Endopleura : the innermost seed-coat, 321. Endorhizse : a synonyme for Endogens. Endorldzal : said of an embryo which has the radicle sheathed by the cotyledon or plumule wrapped around it. Endosmdse, or Endosmdsis, 33. E'ndosperm : the albumen of the seed, 532 GLOSSARY AND INDEX. especially when this is formed in the , embryo-sac of the ovule, 322, 323. Endostome : the orifice of the inner coat of the ovule, 298. Endothelium: the inner lining of the cells of an anther. Enerved : nerveless. Ennea- : nine ; as in Enneagynia, 515. Enneugynous : with nine pistils or styles. Enneandria, 512. Enncdndrous : with nine stamens. Enneape'talous : nine-petalled, 276. Enddal: without a node. Ensate : same as Ensiform : sword-shaped. Entire : the margin whole and even, not toothed or cut, 158, 275. Entophytcs : plants parasitic within oth- er plants. Epacridc.T, 440. Ephemeral : lasting but a day. Epi-, in Greek compounds : upon. Epicdlyx : an involuccl resembling an exterior calyx, as in Mallow. Epical p: the outermost layer of a peri- carp, 310. Epichilium : the upper part of the lip of an Orchid, when different from the lower. Epicdrolline : upon the corolla. Epidermal : relating to the Epidermis: the skin of a plant; 51, 122, 148. Epigeeous : growing on or close to the ground. Epigynous : upon the ovary, 252, 268, 281. Epipetalous : upon the corolla, 281. Epiphldum : outer or corky bark, 121. Epipkyllous : upon a leaf. Epiphytal, or epiphytic : relating to E'piphytes, plants growing affixed to another plant, but not nourished by it, 87. Epipterous : winged at the top. Epispcrm : the outer seed-coat, 320. Equal: regular, or of the same length or number, as the case may be. Equilateral: equal- sided. Equisetacece, 499. E'quitant: riding straddle, 145, 165. Erianthous : woolly-flowered. Ericaceae, 439. Ergot, 498. Eriocaulonacese, 496. Eriogoneai, 466. Erose: eroded, as if gnawed. Erostrate : not beaked. Escalloniere, 425. Essential organs of the flower, 222. Estivation : see ^Estivation. Etozrio : a name for such a fruit as a raspberry and blackberry. Euphorbiacea:, 471. Evalved, or evdlvular : valveless. Evergreen : holding the leaves over win- ter or longer, 172. Exalbuminous : without albumen, 323. Excentric : out of the centre, 325 ; one- sided. Excretions, 57, 178. Excurrent : protruding beyond the apex, as when the midrib of a leaf pro- jects : or running to the very sum- mit, as the main stem of a Fir, 99. Exhalation, 175. E'xocarp : the outer layer of a pericarp, , 312. Exogcn, Exogense, Exogenous Plants, 113, 370. Exogenous structure, 113, 116. Exorhiza} : a synonyme of Exogens ; the radicle in these being Exorhizal: not enclosed or sheathed by the cotyledons or plumule. Exosmdse, or Exosmosis, 33. E'xostome : the orifice of the outer coat of an ovule, 298. Exostosis : an indmated protuberance. Exotheciitm : outer coat of the anther. E'xplanate : outspread or broadly flat- tened. Exserted, exse'rt : protruding beyond, as the stamens out of the corolla in fig. 450. Exstijndate : destitute of stipules, 171. Exterior : as applied to the parts of a blossom, the same as anterior. Extine : the outer coat of a pollen-grain, 286. Extra-axillary : out of the axil, 99, 220. Extrorse : turned outwards, 282. Faries : the general aspect. Falcate, falciform : scythe-shaped ; flat and curved, the edges parallel. Families, 359. Fan-shaped : see Flabelliform. Farina : starch, 54. Farinaceous : mealy; containing starch. Farinose : covered with mealy powder. Fdsciate : banded ; applied also to mon- strous stems which grow flat. Fasciation : the singular monstrous ex- pansion of stems, &c. as in the gar- den Cock's-comb. Fascicle : a close cyme or cluster of flowers, 219; a bundle of leaves crowded like those of the Larch, fig. 213. Fascicled : growing in tufts or clusters, 84, 142. GLOSSARY AND INDEX. 533 Fasciculate : in small tufts. Fastigiate: close, parallel, and upright. Faux (pi. fauces) : the gorge or throat. Fdveolate, /arose : with deep pits, like honeycomb. Feather-veined: having veins all pro- ceeding from a midrib, 155. Feather)/ : see plumose. Ferula: starch, 54. Female flower : see Fertile flower. Fene'strate: pierced with one or more holes, like windows. Ferrugineous or ferruginous : of the color of iron-rust. Fertile: capable of producing fruit. Stamens are also said to be fertile when their anthers contain good pollen. Fertile flower: one having pistils, 261. Fertilization, 300. Fibre, 41. Fibril : a delicate fibre-like body ; the root-hairs, 81. Fibrilliform tissue, 48. Fibrillose: bearing fibrils : diminutive of fibrous. Fibrine, 198. Fibrous or fibrose : composed of slender threads or fibres. Fibro-vascular tissue or system, 50. Ficldle-shaped : obovate and contracted on each side. Fig, 215, 475, and fig. 590-592. Filament : the stalk of an anther, 223, 281. Or any slender thread. Filamentous, or filamentose : composed of threads or filaments. Filices (Ferns), 500. Filicology : the part of Botany which treats of Ferns. Filiform : shaped like a thread ; slender and terete, 166. Filipe'ndulous : hanging from a thread, as the tuberous roots of Spiraea fili- pendula. Fimbriate : fringed ; bordered by slen- der processes or appendages. Fimbrillate or fimbrilliferous : diminu- tive of the last. Fingered: see Digitate. Fissiparous : propagating by division into two portions. Fistular or Fistulose: hollow through its length, as the leaves of Onion. Fldbellate, or flabe'lliform : fan-shaped ; broadly wedge-shaped with the summit rounded. Flacourtiaeeai, 392. Fldgellate: bearing flagella, i. e. runners, like those of the Strawberry. Flageiliform : long, taper, and supple, 45 * like the thong of a whip ; runner- like. Flavescent : yellowish or pale yellow. Flavous : }-ellow. Flax, 402. Fleshy : succulent, or of the consistence of flesh, 84. Fle'xuose, or flexuous : zigzag ; bent alter- nately inwards and outwards. Floating : growing on the surface of water. Floccose : bearing or clothed with locks of soft hairs or wool. Flora (the goddess of flowers) : the ag- gregate of the species of plants of a country ; or a work systematically describing them. Floral : belonging to the flower. Floral envelopes : flower-leaves, 222, 268 Florescence: same as anthesis. Floret : a small flower, or a separate blossom of a so-called compound flower. Florideai, 509. Floriferous : flower-bearing. Fldsculous: composed of or bearing flos- culi, i. e. florets ; or composed of tubular flowers only. Flower, 70, 221. Flower-bud, 209, 224. Flowering, 204. Flowering Plants, 69, 369, 375. Flowerless Plants, 69, 330, 499. Fluitant : floating on water. Fluviatile : belonging to flowing water. Fly-traps, 168. Foliaceous: leaf-like, i. e. thin, membra- naceous and green; or bearing leaves. Foliar: belonging to leaves (folia). Foliation : leafing out. Foliate : clothed with leaves ; or, with a numeral prefix, denoting the num- ber of leaves ; as, bifoliate, two- leaved : trifoliate, three-leaved, &c. Fdliolate: consisting of leaflets (fo- liola) ; as, bifoliate, a leaf having two leaflets, or trifoliolate, having three leaflets, &c. Fdliose : bearing numerous leaves. Follicle: a simple pod opening down one side ; 315, fig. 579. Follicular, of the nature of a follicle. Foramen : an aperture or orifice, 298. Forami'nulose : pierced with small holes. Fdrcipate : forked like a pair of pincers. Forked: branching into two or more divisions. Fornicate : arched over, bearing a Fornix, pi. fdrnices : little arched scales in the' throat of a corolla, as in that of Hound's-tongue. 534 GLOSSARY AND INDKX. Fdveate : pitted, having fovea or depres- sions of the surface. Fdveolate : marked with little pits or de- pressions (fove'olce). Fovilloz: minute particles in the fluid contained in pollen, 286. Free : separate ; not uuited with dis- similar parts, 250. Fringed : see Fimbriate. Frond: the foliage or Ferns (500), Liverworts (504), &c., 67. Frondescence : the act of leafing. Frondose : leafy, or more commonly it now means frond-like, or producing a frond instead of ordinary foliage, 504. Fructification : fruiting, or the fruit and what attends it. Fructification, organs of: the stamens and pistils. Fruit, 308. Fruit-dots, of Ferns, 501. Frumentaceous : producing starch, or re- lating to corn (frumentum). Fnistulose : consisting of small portions or fragments. Frutescent : becoming shrubby. Fruticulose : very small and shrubby. Fruticose : shrubby ; relating to a Frutex : a shrub. Fucaceae, 509. Fugacious : falling off or perishing very early, as the calyx of the Poppy, and the corolla of Cistus ; 172. Fulcrate : belonging to or furnished with fulcra (props), i. e. with append- ages such as tendrils, prickles, stip- ules, &c. Fidiginous, or fuliginose : sooty ; dark and deep Drown. Fulvous : tawny : orange-yellow mixed with gray. Fumariacea% 389. Fundamental organs, 70. Fungi, 507. Fungiform : mushroom-shaped. Fungilliform : diminutive of the last. Fungose : spongy in texture. Funiculus : the seed-stalk, 297, 321. Funnel-shaped, funnel-form : sec Infun- dibuliform, 277. Furcate : forked, the forks spreading. Furfuraceous : scurfy. Furrowed: see Sulcate. Fuscous : grayish-brown. FUsiform : spindle-shaped ; 84, fig. 138. Fustic, 475. Galbanum, 427. Gallmlus : a fleshy and closed strobile imitating a berry, as a Juniper- berry, 320. Galea: a helmet; an arched sepal or petal, 278, fig. 458. Gdleate : having, or shaped like, a hel- met. Galingale, 490. Galls, 477. Gamboge, 400. Gdmoplii/llous : composed of leaves united by their edges, 275. Gamope'talous : composed of united pe- tals, 249, 275. Gamose'palous : of united sepals, 249. Gelatinous coils in cells, 40. Geminate : in pairs. Gemma : a bud or growing point. Gemmation : budding growth, 31. Ge'mmule : a young bud ; the plumule. Genera : plural of genus. General : the opposite of partial ; as the General involucre of a compound um- bel, &c, 216; Generic: relating to the genus. Geniculate: bent abruptly like a knee. Gentianacese, 456. Gentianine (Gentian), 457. Genus, 358. Geographical Botany : the study of plants in respect to their geograph- ical distribution. Geraniacea:, 403. Germ : the eye of a bud ; or any grow- ing point ; or an embryo, 323. Germen : an old name for the ovary. Germinal vesicle, 306. Germination : growth of the embryo from the seed, 71, 328. Gerontoijoious : belonging to the Old World. Gesncriaceoe, 447 Gibber: an enlargement, or gibbosity of any sort, on one side of a calyx, a fruit, &c. Gibberose or gibbous: swollen or en- larged on one side. Gills of Fungi, 500. Ginger, 490. Ginseng, 428. Glabrous : smooth, i. e. destitute of hair- iness. Glabrate : smoothed, or becoming near- ly glabrous. Glddiate : sword-shaped. Glands : any secreting apparatus, 52. The name is also given to any pro- jection or appendage the nature and function of which is not obvi- ous, 264. Glans is also the classi- cal name of an acorn and chestnut. Glandular, glanduliferous, glandulose : bearing glands, or gland-like in texture. Glandular hairs, 52. GLOSSARY AND INDEX. 535 Glandular icoody tissue, 43. Glarcose: growing in gravelly places. Glaucescent : verging upon or slightly Glaucous: covered with a whitish bloom, which rubs off, as the surface of a cabbage-leaf or a plum, or so whitened as to appear to have a bloom, 56. Globose : spherical or nearly so. Globular : nearly globose or spheri- cal. Glochideou?, or glochidiate : barbed ; hooked back at the point, like the barb of a fish-hook, or with two or more such barbs at the point. Glomerate : clustered into a Gldmerule : a capitate cyme, i. e. a cyme condensed into a head, 219. Glossology: the department of Botany which explains the technical terms of the science, 15. Gluniaceous: bearing, or resembling glumes. Glume : one of the husks or chaff of Grasses, &c., 497. Glumelle : an inner glume or palea. Gluten, 197. Glutine, 198. Go'nophore : a stalk elevating both sta- mens and pistil, 267. Gooseberry, 421. Gossijpine: cottony. Gourd (a pepo), 423. Grafting, 100. Grain, 314. Graminese, 497. Granadilla, 422. Granular : composed of grains or gran- ules. Granulate: composed of little kernels or coarse grains. Granules: anv minute particles. Grape, 408. Green layer of the bark, 121. Grossulacea?, 420. Grumous, or grumose: consisting of clustered grains. Guaiacum, 405. Guava, 418. Gum Animi, 400. Gum Arabic, 414. Gum Elemi, 407. Gum Traga- canth and Senegal, 414. Gutta-percha, 57. Guttate : sprinkled with colored dots or small spots. Guttiferae, 400. Gymnocdrpous : naked-fruited. Gymnospermia, 315. Gymiwspermous : naked-seeded, 296. Gymnosperms, or Gvmnospermous Plants, 297, 371, 479. Gyiuicium : the pistils of a flower, 223. Gynandria, 513 Gyndndrous : stamens borne on the pis- til, especially on the stvle; 253, 281, fig. 468. Gynobase : the base of a style, or sum- mit of a receptacle, on or around which two or more carpels are in- serted, as in Rue, Sage, Geranium, &c, 267. Gynophore : the stalk of a pistil, 267. Gyrate or gyrose : bent round, or bent back and forth. Habit (Habitus): the general aspect of a plant. Habitat: the habitation, or situation in which a plant is naturally found. Hackbcrry, 474. Haematine, 414. Hannodoracece, 492. Hairs, 52. Hairy : clothed or beset with hairs, which are separately distinguish- able. Halberd-shaped, or Halberd-headed: see Hastate. Halorageas, 420. Halved: sec Dimidiate ; appearing as if one half was absent. Hamamelacess, 425. Hamate, ovhamose: hooked. Hdmulose: diminutive of hamate. Hastate : halberd-beaded ; shaped like a halberd, viz. with a spreading lobe at the base on each side ; 157, fig. 250. Hazel-nut, 476. Head: see Capitulum ; 213, fig. 320, &c. Headed: same as capitate. Heart-shaped: see Cordate. Heart-wood, 35, 124, 126. * Hebetate : blunted, having a soft obtuse point. Helicoid : coiled into a helix or snail- shell, or tending to be rolled up ; as in Fig. 332. Helmet: see Galea, 278. Helobious : living in marshes. Heivolous : grayish-yellow mixed with some red. Hemi- in Greek derivatives : halved or half; as Hemi-andtropous : half-anatropous. He'micarp : a half-fruit of Umbelliferae ; same as mericarp. Hemitropal, or hemitropous : nearly the same as amphitropous. Hemp, 475. Hepatica;, 503. Hepta : the Greek numeral seven, used in the following compounds. 536 GLOSSARY AND INDEX. Heptagynia, 515. Heptdgynous : having seven pistils or styles. Heptdmerous : the parts in sevens. Heptandria, 512. Heptdndrous : with seven stamens, 280. Heptape'talous : of seven petals, 276. Herb, 101. Herbaceous : not woody ; of a soft text- ure like an herb, 101, 102. Herbarium : the botanist's collection of dried specimens of plants, 518. Hermaphrodite: bisexual, 261. Hesperidium : a firm-rinded berry like an orange, 311. Hetero-, in Greek derivatives : unlike ; as Heierocdrpous: having two kinds of fruit. Heteroceplialous : bearing two kinds of heads ; as in Baccharis. Heterodrdmous, 140. Heterdgamous : bearing two sorts of flowers, 436. Heterogeneous : of two or more kinds. Heterdtropous, or heterutropal, ovule or seed : same as amphitropous, 300. Hexa-, in Greek derivatives ; six. Hexagynia, 515. Hexdgynous: having six pistils or styles. Hexdmerous : the parts in sixes, 234. Hexandria, 512. Hexdndrons : with six stamens, 279. Hexape'talous : six-pctalled, 276. HexaplnjUous : six-leaved, 275. Hexdpterous : six-winged. Hexase'palous : with six sepals, 272. Hexasle'monous : having six stamens. Hickory-nut, 476. Hidden-veined : where the veins are not visible, as those of the leaves of Pinks and Houseleeks. Hilar : relating to the hilum. Hilum: the scar, or point of attachment of the seed, 297, 321. Hippocastanaceaj, or Hippocastaneas, 410. Hippocre'piform : horseshoe-shaped. Hirsute: clothed with coarse hairs. Hispid : beset with stiff bristly hairs. Hoary : grayish-white from a fine pu- bescence. Homocarpous : bearing fruits all of one kind. Homodrdmous, or homodromal, 140. Ilomdgamous : when all the flowers of a head, &c. are alike, 436. Homogeneous : all of the same nature or structure. Homologous : of the same name ; said of parts which are of the same morphological nature ; e. g. bracts, sepals, petals, stamens, and sim- ple pistils are homologous with leaves; 225, 231. See Analogous. Homologue : an homologous part. Homdmallous (leaves, &c.) : originating all round an organ, but directed or curved round to one side of it. Homomdrphous : of one form. Homotropous, or homotropal (embryo) : curved in the same way as the seed, as in the Cliickweed, fig. 621. Hops, 475. Horny: see Corneous. Horizontal system, 50, 112. Hortus Siccus: same as herbarium. Huckleberry, 439. Humifuse : spreading flat on the ground. Humus, Humic acid, 57. Hyaline : transparent, or partly so. Hybrid: a cross-breed between individ- uals of two species, 357. Hydrangiens, 425. Hydrocharidacese, 487. Hydroleacea?, or Hydrolese, 452. Hydrophyllaceae, 451. Hydrophyte : a water-plant. Hydropterides, 502. Hycmal : belonging to winter. Hyinc'nium : the gills of Mushrooms, &c, 507. Hymcnophyllere, 501. Hypdnthium : a naked fleshy receptacle, like a fig. Hypcricaceas, 394. Hypo-, in Greek derivatives : under. Hypochilium : the under part of the lip of Orchids, when jointed or other- wise distinguishable. Hypocrateriform, or, moi - e properly, Ilypocraterimdrphous : salver-shaped ; i. e. with a limb spreading flat at right angles to the tube; 277, fig. 457. Hypogceous, or hypogcean (flowers or fruits) : borne under ground, 76, 78, 328. Hypdgynous: growing under the pistil, and free, 250, 268, 280. Ilypophyllous : growing on the lower side of a leaf. Hysteranthous : plants whose leaves ap- pear later than the blossoms, as the Eed Maple. Hysterophytal : living on a matrix, either of dead or living organic matter. Hysterophytes : same as Fungi, &c. Icos-, in Greek compounds : twenty. Icosandria, 512. Icosdndrous : having 20 stamens or more inserted on the calyx, 280. Illecebrese, 396. Imbibition, 177. GLOSSARY AND INDEX. 537 Imbricate, imbricated, imbrieative : over- lapping, the outer covering the in- ner, and breaking joints, like tiles on a roof, 144, 269. Immarginate : not margined. Immersed: growing wholly under water. Impari-pinnate : pinnate with an odd leaflet; 163, fig. 288. Imperfect flowers: wanting either sta- mens or pistils. Impregnation : same as fertilization. Inane: empty. Incanous: hoary-white. Incised: cut irregularly and sharply; 159, fig. 259. Included: not projecting beyond; en- closed. Incomplete floicer : wanting some one or more kinds of organs, 259. Incrassated : thickened. Incrustations in cells, 58. 1'ncubous : the apex of each leaf lying over the base of the next, as in many Hepaticre. Incumbent : leaning or lying upon : said of the cotyledons when the radicle lays against the back of one of them/ 390, 326, fig. 705 ; or when the anther lies on the inner side of the filament, 282. Incurred: bent or curved inwards. Indefinite: either uncertain in num- ber, or too many to be readily counted, 242. Indefinite growth, 100. ltd finite inflorescence, 210. Indchiscent (fruits) : not opening, at least not in a regular way, 310, 313. Indeterminate inflorescence, 210. India-rubber, 57. Indigenous : of spontaneous and original growth in a country. Indigo, 414, 415. Individual, 20, 131, 352. Individuality, 132, 352. Indumentum : any hairiness or downy covering. Indiiplicate: bent or folded inwards, 145, 273. Indiisium : the proper covering of the fruit-dots of Ferns ; any peculiar membranous covering, 501. Inequilateral : unequal-sided. Inferior: underneath, 252; or same as anterior : thus the inferior petal, &c. is the same as the anterior one, 237. Inflated: bladdery. Indexed: abruptly bent inwards. Inflorescence, 209. Infra-axillary: originating below the axil. Infundibular, infundibuliform : funnel- shaped ; i. e. a tube enlarging up- wards ; 277, fig. 1049. Innate : borne directly on the apex of a thing, 282. Innovations : new shoots or new growths. Inorganic : unorganized. Inorganic constituents, I'd. Inosculating : opening into each other ; anastomosing, 49. Inserted: attached to, 224, 250. Insertion: the place or the mode of junc- tion of leaves with the stem, &c., 133. Inter-, in composition : between ; as Intercellular : between the cells. Intercellular spaces or passages, 24, 50. Intercellular system, 50. Interlaced tissue, 48. Internal glands, 51. Internodes, 92. Interpe'tiolar : between the petioles, 171. Interruptedly pinnate, 164, fig. 285. Intine: the inner coat of a pollen-grain. Intrafoliaceous : within or before a leaf, 171, as the stipules in fig. 305. Introflexed: bent strongly inwards. Intrdrse: turned inwards towards the axis, 282. Intruse: appearing as if pushed inwards or indented. Inverse: inverted; suspended. Involucellate : furnished with an Involuce'llum, or involved: a secondary or partial involucre, 216. Involucrate : provided with an Involucrum, or involucre : an outer or accessory covering ; a set of bracts surrounding a flower-cluster ; 214, fig. 321, &c. Involute : rolled inwards, 144, 273. Ipecacuanha, 393, 433. Iridacece, 490. Irregular : unequal in size or in shape, 253, 277. Irregularity, 253. Irritability, 345. Isdchroiis : one-colored. Isoetineas, 502. Isdmerous, or isomeric : the parts equal in number. Isoste'monous : the stamens as many as the petals or sepals. Jalap, 455. Jasminacens, 459. Jelly, 55, 310. Jointed: separate or separable trans- versely into pieces (joints), 92. Juba: a loose panicle, as of Grasses. Juga : the ridges of the fruit of Umbel- lifera3, 426. 538 GLOSSARY AND INDEX. Jugce : the pairs of partial petioles or leaflets of a pinnately-compound leaf, 164. Juglandaceaj, 476. Jujube, 408. Julus : a name for a catkin. Julaceous : shaped like or resembling a catkin. Juncacea?, 495. Juncagineae, 487. Jungcrmanniacese, 505. Juniper-berries, 480. Jute, 400. Keel: see Carina, 254. Keeled: furnished with a keel or sharp ridge underneath. Kernel of an ovule, 297, or seed, 322. Key-fruit, 314. Kidney-shaped: see Kcniform ; 157, fig. 245. Kingdom, 362, 15. Kinic acid, 433. Kino, 414. Knot : see Node, 92. Knotted: a cylindrical body swollen into knobs at intervals. Krameriacea:, 412. Labe'llum : the lip, or lower petal of an Orchidcous flower. Labiatse, 450. Labiate: two-lipped, 278. Labiatiflorse, 436. Lac, 475. Laciniate : slashed ; cut into narrow in- cisions ; these are called laciniaz. Lactescent : yielding milky juice. Ldcunose: full of depressions or exca- vations (laciince). Lacustrine: belonging to lakes. Ladanum, 394. Lcevigate : smooth as if polished. Lage'niform: shaped like a Florence flask (lagena). Lalo, 399. Lame'lloz : thin plates, like the gills of an Agaric, 507, &c. Lamellar, or lamellate : composed of fiat plates. Lamina (a plate) : the blade of a leaf, petal, &c, 145, 276. Lanate, lanose: woolly; i. e. clothed with soft interlaced hairs. Lanceolate: lance-shaped; fig. 239. Lanuginous : cottony or woolly. Latent buds, 167. Lateral : belonging, or attached to, the sides of an organ. Latex : milky or proper juice, 49. L^aticiferous tissue or vessels, 49. Lauracese, or Laurinese, 466. Lax: loose; the opposite of close or crowded. Layer inq, 102. Leaf, 133. Leaf-arranaement (phyllotaxis), 133. Leaf bud, 72, 93. Leaf-green, 58. Leaflet : a separate piece or partial blade of a compound leaf, 163. Leafstalk, 145, 170. Leaf-scars, 94. Leathery : see Foliaceous. Legume: a fruit like a Pea-pod, 315. Legumine, 198. Leguminosag (Leguminous Plants), 412. Leguminous : relating to legumes. Lemnaecae, 486. Lemon, 401. Lentibulacea?, 445. Lenticels: little spots on the bark, whence roots often issue. Lenticular : lens-shaped ; double-convex. Lentiginose: freckled, or dusty-dotted. Leptus : sterile transformed stamens. Lepidote : leprous ; scaly or scurfy, 52. L,eucanthous : white-flowered. Liber : the inner fibrous bark, 120, 127. Lid: see Operculum, 502. Lichenes (Lichens), 505. Lichenology : the part of Botany devoted to Lichens. Licorice, 414. Ligneous: woody in texture. Lignine, 36, 195. Lignum-vitaa, 405. Ligidate: strap-shaped, 255 ; having a Ligule: a strap-shaped corolla, 255, fig. 325, d ; the appendage between the blade and the sheath of the leaf in Grasses, 170. Ligulifloroe, 436. Liguliforous : when a head consists of ligulate flowers only, as Cichory, fig. 323. Liliacese, 493. Liliaceous: lily-like, 276. Limb (limbus, a border) ; the expanded part or border of a corolla, calyx, &c, or the lamina or blade of a petal, &c, 145, 276. Limbate : bordered. Lime, 401. Limnanthaceoe, 404. Linacere, 402. LJne : the twelfth of an inch. (In deci- mal measures, the tenth of an inch.) Linear : narrow and much longer than broad, the two margins parallel ; fig. 240. Lineate : marked with lines. Lineolate : marked with fine or obscure lines. GLOSSARY AND IXDEX. 539 Linguiform, or Ungulate: tongue-shaped, as the leaves of Hound's-tongue. Lip: the two lobes a bilabiate calyx or corolla ; the lower petal of an Orchidcous plant. Littoral, or litoral: growing on shores. Livid : pale lead-color. Loasacete, 421. Lobe : any division or projecting part of an organ, especially a rounded one, 275. Lobed, lobate : divided into lobes ; fig. 260, 264. Lobeliacere, 438. Ldbulate : bearing small lobes (lobuli). Ldcellate: having secondaiy cells (or locelli). Loce'llus (plural, locelli) : a secondary cell, or a division of a cell. Ldculament, 316 ; same as loculus. Ldcular : having cells. Loculicidal, or loculicide : dehiscence opening directly into the back of a cell; 316, fig. 583, 585. Ldculose : partitioned off into cells, as the pith of Poke, &c. Loculus (plural, loculi): the cells of an ovary, anther, &c. Lociista : a spikelet or flower-cluster of Grasses. Lddicules (lodiculce); the minute scales inside of the paleae of Grasses, 497. Loganiaceas, 433. Logwood, 414. Loment: a jointed legume; 315, fig. 581. Lomentaceous : bearing or resembling a loment. Longitudinal tissue or system, 45, 50, 112. Lonicerere, 431. Loranthacea?, 469. Lorate : thong-shaped. Lucid: shining. Lunate : crescent or half-moon shaped. Liinulate : diminutive of the last. LMpuline : waxy grains on the scales of Hops. Lurid: dingy brown. Lutescent : yellowish. (Luteus : yellow). Lycopodiacese, 501. Lycdtropous, or lycdtropal : an orthotro- pous ovule curved into a horse- shoe form. Lyrate, lyre-shaped, 161, fig. 138, 278. Lyrately pinnate, 164, fig. 285. Lythraceae, or Lythariea?, 418. Mace: the arillus of Nutmeg, 322, 383. Maculate : spotted or blotched. Madder, 432. Magnoliaceas, 381. Mahogany, 401. Maize, 498. Male flower, 261. Malp'ighiaceae, 409. Malpighiaceous hairs: hairs fixed by their middle, as in the foregoing order, in Cornus, &c. Malvaceae, 397. Mdmillate, or mdmillar : bearing little prominences on the surface. Mdmmceform : teat-shaped. Mammee-apple, 400. Mammose : bearing larger prominences, like breasts. Mango, 406. Mangosteen, 400. Manicate (gloved) : covered with a woolly coat which may be stripped off whole. Manilla hemp, 490. Manna, 460. Many-cleft : cut as far as the middle into several divisions, 159. Many-headed : see Multicipital. Marantaceae : see Cannacese. Marcescent: gradually withering with- out falling off, 279. Marchantiacese, 504. Marginal : belonging to the margin. Marginate : furnished with a margin of different texture or color from the rest. Maritime : belonging to the sea-shore. Markings on cells, 3, 6. Marmorate : marbled. Marsiliacese, 502. Mas : male, masculine ; belonging to the stamens. Masked: see Personate, 278. Mealy : see Farinaceous. Medial: belonging to the middle. Medulla: pith, 118. Me'dullary rays, 117, 119. Medullary sheath, 119. Medullose, or medullary : pith-like. Meioste'monous : having fewer stamens than petals. Melanospermese, 509. Melanthaces, 494. Melastomacea?, 418. Meliacese, 401. Melon, 423. Membranaceous, or membranous: thin and soft, like a membrane. Meniscoid: shaped like a meniscus or concavo-convex lens. Menispermaceas, 383. MenyanthideaB, 457. Mere'nchyma, 41. Me'ricarp: half a cremocarp, 426. Merismdtic: dividing into parts, 28. Me'rithall : a name for an internode. Merous, in Greek compounds : the parts 540 GLOSSARY AND INDEX. of a flower : sec Dimerous, Trime- rous, &c. Mesembryanthemacea3, 397. Me'socarp : the middle layer of a peri- carp, 310. Mesophldum : the middle bark or green layer, 121. Mesophyllum : the parenchyma of a leaf between the skin of the two sur- faces. Metamorphosed: that which has under- gone. Metamorphosis : the transformation of one or^an into another homologous one, 228,231. Micropyle: the orifice of a seed, 29S. Midrib : the central or main rib, 155 Milky juice, 49. Mimoseffi, 413. Mineral constituents of plants, 179. Miniate : vermilion-color. Mitriform : mitre-shaped, 503. Molluginea;, 395. Monadclphia, 513. Monadelphous : with filaments united into a tube, or ring ; 280, fig. 462. Monandria, 512. Mondndrous : with a single stamen, 279. Mondnlhous : one-flowered. Monihform : nceklacc-shaped ; cylin- drical and contracted at intervals. Monimiacese, 382. Monkey-bread, 399. Mono-, in Greek compounds : one or single. Monocdrpellary : of one carpel. Monocdrpic, or monocdrpian : once-fruit- ing, 101. Monocephalous : bearing a single head. Monochlamydeous : with a single floral envelope ; i. c. apetalous, 260. Monoclinous : hermaphrodite. Monocotyle'donous : one-cotyledbned, 79, 326. Monocotyledons or Monocotvledonous Plants, 113, 326, 370, 482. Moi'oecia, 513. Monoecious : stamens and pistils in sep- arate flowers on the same individ- ual, 262. Monogamia, 516. Monogynia, 515. Mondgynous: with one pistil or style, 287. Monoicous : same as monoecious. Mondmerous: the parts of the flower single, 234. Monope'talous : one-petalled, but it is used for gamopetalous, viz. petals more or less united into one bodv, 249, 275. Monophyllous : one-leaved, of one piece, 275. Mondpterous : one-winged. Monopyrenous : one-stoned. Monosepalous : the calyx of one piece, 249. Monospe'rmous : one-seeded. Mondstichous : in one vertical rank, 134. Hfondsfylous : with one style. Monotropeas, or Monotropaceie, 440. Monster, monstrous (430) : developed in an unnatural manner. Morphine, 57. Morphology, 14, 60, 224. Mdrphosis : the manner of development. Moschate : exhaling the odor of musk. Moulds, 65. Mucilage : dissolved vegetable jelly, or dextrine, 55, 193. M^ucilaginous, mucose, or mucous: slimy. Mucro : a short, sharp point. Mucronate: abruptly tipped with a mu- cro ; 162, fig. 2*76, 231. Mucrdnulate: tipped with a minute mu- cro. Mulberry, 475. Mule : a hybrid. Multangular : many-angled. Multi-, in Latin derivatives : many; as, Multicipital (nuilticeps) : many-headed; where several buds or shoots pro- ceed from the crown of one root. Multifarious : many-sided. Multi fid: many-cleft, 159. M^ultifidrous : many-flowered. Multijugate : in many pairs. Multildcular : many-celled. Multiple : compound. Multiple fruits, 309, 318. Multise'rial : in several horizontal ranks. Multiseptate : many-partitioned. Miiricate: rough with short and hard points. Muriculate : minutely muricate. Musaceas, 490. Muscardine, 508. Muscariform : brush-shaped. Musci (Mosses), 502. Musciform : moss-like. Muscology: the department of Botany which treats of Mosses. Mustard, 389. Miiticous : pointless ; blunt. Mi/celium, 507. Mycology, or Mycetdlogy : the depart- ment of Botany which treats oi v Fungi. Mycropyle : see Micropyle. Myricaceee, 477. Myrsinacese, 443. Myristicaceae, 383. Myrrh, 407. MyrtacesE, 418. GLOSSARY AND INDEX. 541 Naiadaccae, 487. Naked flowers : same as achlamydeous ; or destitute of involucre, &c. Naked ovules and seeds, 296, 320. Karnes of species and genera, 363 ; of orders, tribes, &c, 373. Ndpiform: turnip-shaped, 84. Natant: floating under water. Natural system, 365, 366. Naturalized: species introduced, but growing completely spontaneous, and propagating by seed. Navicular : boat-shaped . Nelmlose : clouded. Neck: the junction of root and stem. Necklace-shaped: see Moniliform. Nectar : the honey of a flower, or any sweetish exudation. Nectary (nectarium) : a place or thing in which nectar is secreted : for- merly applied also to any anoma- lous part or appendage of a flower, whether known to secrete honey or not, as to the spur-shaped petals of Aquilegia, fig. 647, or the two singular-shaped petals of Aconi- tum, 257, fig. 402, 404. Needle-shaped : see Acerose. Nelumbiaceae (Nelumbo), 385. Nemeous : filamentose ; composed of threads. Nervation : the arrangement of the Nerves: parallel and simple veins. Nerved : nervate ; furnished with nerves, 154. Nervose : abounding in nerves. Netted: same as reticulated. Nelted-veined, 1 54. Neurose : same as nervose. Neutral : without sexes. Neutral flowers : having neither stamen nor pistil, 263, 436. Neutral quaternary products, 196. New Zealand Hemp, 492. Niduhmt : nestling in. Nitid (nitidus) : smooth and shining. Niveous : snow-white. Nodding: curved so that the apex hangs down. Node (knot) : the place on a stem where a leaf is attached, 92. Nodose : knotty ; swollen in some parts, contracted at others. Nodulose: diminutive of the last. Normal : according to rule. Notate : marked by spots or lines. Notorhizal : the radicle bent round to the back of one cotyledon ; same as incumbent. Niirumentaceous : nut-like. Niicelle : same as nucleus. Nut-form : nut-like. 46 Nucleus: the kernel, 297, 320, 322. Nucleus of a cell, 26. Nuculanium : a name for a berry like a grape. Nucule : a diminutive nut, stone, or kernel. Niiculose: containing nucules or nut- lets. Numerous: same as indefinite. Nut, 314. Nutlet : a small nut, or the small stone of a berry -like drupe. Nutmeg, 383. Nutant : nodding. Nutrition, 61, 177. Nux- vomica, 434. Nyctaginacea;, 463. Nymphaaaeeas, 385. Oat, 498. Ob- (over against) signifies inversely; as, Obcom pressed : flattened fore and aft, in- stead of laterally. Obcdrdate : heart-shaped inverted ; 1 62, fig. 274, 233. Obldnceolate : lance-shaped, but broader upwards. Oblique, referring to shape, unequal- sided, 165. Obliteration, 309. Oblong: elliptical, or approaching it, and much longer than wide ; fig. 242. Obdvate: inversely ovate ; 157, fig. 232. Obtuse: blunt; the apex an obtuse an- gle; 162, fig. 270, 236. Obverse: same as ob. O'bvolute : a modification of convolute, 145. Oce'llate : eyed ; a circular patch of , color within another patch. Ochrea (a boot) : a tubular stipule ; , 171, fig. 305. Ochreate : furnished with ochrcee. Ochroleiicous : ochre-colored (pale dull yellow) verging to white. Octo- : eight ; in composition in such words as the following. Octagijnia, 515. Octdgi/nous : with eight pistils or styles. Octdmerous : the parts in eights. Octandria, 512. Octdndrous : with eight stamens. Octope'talous : of eight petals, 276. O'culate: eyed; same as ocellate. Officinal (belonging to the shop) : ap- plied to plants, &c. used in medi- cine or the arts. Offset, 102. Oilnut, 469. Oils, 56, 57. 542 GLOSSARY AND INDEX. Okra, 398. Oleaccas, 459. Oleraceous : of the nature of, or fit for, pot-herbs. Oligo-, in Greek derivatives : few ; as Oligandrous : having few stamens. Olirjospe'rmous : few-seeded. Olive, Olive-oil, 4G0. Onagraceae, 419. One-celled plants, 61. One-sided: see Secund and Unilateral. Oophoridia : the larger and compound spores of Lycopodiaceas. Opaque : the reverse of shining ; dull. Ope'rculate : furnished with a lid or Operculum: a lid, such as that of the spore-case of Mosses, 502. Ophioglosscaj, 501. Opium, 389. Opposite (leaves, &c.) : opposed to alter- nate, that is, placed over against each other, 78,97, 133, 141. A stamen, &c. is said to be opposite a petal, when it stands before it (248), as in fig. 435 and 670. Oppositifolious : opposite a leaf, as the tendrils of Vitis, fig. 767, and the peduncles of Phytolacca, fig. 1086. Orange, 401. Orbicular : circular in outline. Orchidaceae, 488. Orders, 359. Ordinal : relating to orders. Organic constituents, 179, 180. Organization, 17. Organography, 14, 60. Organogeny : the development or for- mation of organs, 268. Organs, 18. Organs of Reproduction, 70. Organs of Vegetation, 68, 70, 204. Orobanchaceae, 446. Orris-root, 491. Ort/iopldceous (embryo) : with incum- bent and conduplicate cotyledons, as in Mustard. Orthdtropous, or orthdtropal ovule ; 298, fig. 526. The term when applied to the embryo is used as the con- trary of antitropous, i. e. having the radicle next the hilum, as in an anatropous seed. Osage Orange, 475. Osmundaceaj, or Osmundinese, 501. Osseous : of the texture of bone. Ouari Poison, 434. Oval: broadly elliptical; 157, fig. 229. O'vury : the ovule-bearing portion of a , pistil, 223, 287. Ovate : egg-shaped, or like the longitu- dinal section of an egg, fig. 241. Ovoid : a solid ovate or oval. Ovulate, ovuled, or ovuliferous : bear- , ing ovules. Ovule : an unimpregnated seed or body destined to become a seed, 223, 297. Oxalidaccae, 404. Palate : an inward projection of the lower lip of a personate corolla; 278, fig. 459, 460. Pdlea, or palet : a chaff ; one of the bracts on the receptacle of Com- posite, 215, 435 ; one of the inner bracts or glumes of Grasses, 497. Paleaceous : chaff-like, or bearing chaff. Pa/e'ola : diminutive of palea ; one of the minute innermost scales of the flower of Grasses. See Squa- mella. Palmae (Palms), 484. Palmate : lobed or divided so that the sinuses all point to the apex of the petiole, either moderately, as in a Maple-leaf, or so as to make the leaf compound, as in Horsechest- nnt, when it is the same as Digitate ; 161, 163, 164. Palmalely lobed, cleft, parted, &c, 161. Palmalely 2 - plurifoliolate, 164. Palmate! >/ veined, 156. Palmdtifid: pal mately cleft ; fig. 265. Palmdtisect : palmatcly divided ; fig. 267. Paludose, palustrine : inhabiting marshes. Pandanacea?, 485. Pdndurate, or pandiiriform : same as fiddle-shaped. Panicle : a raceme, branched irregular- ly; 216, fig. 326. Panic/cd, or paniculate: arranged in a panicle. Papaveracete, 388. Papaw, 383, 422. Papayaceae, 422. Papery : of the consistence of letter- paper. Papilionaceae, 413. Papilionaceous: butterfly-like, 253. Papillose, or papillate : bearing small, soft projections (papillae, nipples or pimples). Pappose, or pappiferous : bearing a Pappus (thistle-down), 260, 314, 435. Papyraceous : papery. Papyrus, 496. Paracorolla : an appendage or duplicate of a corolla, such as was once called a nectary. Parallel-veined or nerved, 154. Pardphgsis : jointed thread-like bodies accompanying the pistillidia of Mosses. GLOSSARY AND INDEX. 543 Parasitic plants, or Parasites: living on the juices of other plants, 88. Parastemon : same as Staminodium. Parenchyma: soft cellular tissue, 41. Parietal : attached or belonging to the walls, 292. Parietes : -walls of an ovary, &c. Paripinnate: same as abruptly pinnate, 163. Parnassiacere, 394. Parsnip, 426. Parted, or partite : cut almost through ; 160, fig. 262, 266. Partial peduncle, 211. Partial pet iole, 164. Partial umbel, 216. Parthenogenesis, 300, 340. Passifloracese (Passion-flowers), 422. Patelliform : kneepan-shaped. Patent : spreading wide open. Patulous : moderately spreading. Pauci-, in Latin derivatives : few ; as Paucijldrous : few-flowered. Peach, 415. Pear, 416. Pear-shaped : ovoid at the extremity, conical at the base. Pe'ctinate : pinnatifid with close-set and equal lobes, like the teeth of a comb (pecten), 160. Pcctine, and Pectic acid, 55, 310. Pedate : palmate, with the lateral lobes asjaiu lobed ; appearing like a bird's foot, 161, fig. 249. Pedately : in a pedate mode. Pe'dicel : the stalk of a particular flower, 211. Pedicellate, pedicelled: having a pedi- cel. Peduncle : a flower-stalk in general. either of one blossom or a whole cluster, 211. Pedunculate-, peduncled : having a pe- duncle. Peloria, 278. Peltate : shield-form or target-shaped ; fixed by the centre or some part of the lower surface ; fig. 248, 681. Peltinerved : peltately veined. Pelviform : open cup-shaped. Pendent, pendulous : hanging down. Penicillate, penicilliform : tipped with a brush of hairs, like a camel's-hair pencil. Parnate: same as pinnate. Penniform : feather-like. Penninerved : same as pinnately nerved or veined. Penta-, in Greek derivatives : five ; as Pentacdrpellary : of five carpels. Pentacdccous : of five cocci. Pentagynia, 515. Pentdqynous : with five pistils or styles, 287. Pentdmerous : of five parts ; 234, 239, fig. 354. Pentandria, 512. Pentdndrous : having five stamens, 279. Pentapetalous : of five petals, 276. Pentaphyllous : five-leaved, 275. Pentdpterous : five-winged. Pentasepalous : of five sepals, 274. Pentdstichous : in live vertical ranks, 135. Pepo: a Gourd-fruit, 312. Pepper, 456, 469. Perennial: lasting year after year, 84. Perfect flower : one having both stamens and pistils, 261. Perfoliate: when the stem appears to pass through the leaf; 165, fig. 293. 294. Perforate : pierced with holes, or having transparent dots which look like holes. Pergame'neous, or pergamentdceous : like parchment. Peri-, in Greek derivatives : around. Pe'rianih (peridnthium) : the floral en- velopes collectively, either of one set (calyx) or of two sets (calyx and corolla), 222. Pericarp : the ovary in fruit, 308. Pericdrpic ; belonging to the pericarp. Perichatial : relating to the Pe'richazlh, or perichatium : the cluster of peculiar leaves surrounding the base of the fruit-stalk of Mosses. Pcriclinium : a name for the involucre of Composite. Pe'riderm : same as Epiphlceum. Pe'rigone, or perigonium : same as Peri- anth. Perigynium : bristles or other organs, of doubtful nature, around the pistil in Cyperacea:, 497. Perigynous : borne on the calyx ; liter- ally around the ovary ; i. e. when the petals or stamens are adnate to the base of the ovary or to the calyx ; 251, 268, fig. 3S8, 3S9, 281. Peripetalous : around the petals. Peripheric: surrounding the circumfer- ence, 325 ; as the embryo around the albumen in fig. 621. Pe'risperm : the albumen of the seed, 322, or that albumen which is formed in the tissue of the nucleus, 323. Pe'ristome, 502. Peritropous, peritropal (seed) : horizon- tal to the axis of the fruit. Perpendicular system of the stem, 112. Persimmon, 443. 544 GLOSSARY AND INDEX. Persistent : remaining, as the leaves of evergreens through the winter, 172 ; and the calyx, &c. of many plants until the fruit is formed, 279. Pe'rsonate : masked ; 278, fig. 459, 460. Pertuse : having slits or holes. Pe'rulate: having peruke or bud-seales. Peruvian Bark, 432. Petal : a leaf of the corolla, 222. Petalme, or pe'tcdoid: petal-like, in color and texture, 260. Pe'tiolar : borne on the petiole. Pe'tiolate, petioled : having a petiole. Petiole: leafstalk, 145, 170. Petidlulate: the leaflet stalked, 164. Petiolule: the stalk of a leaflet, 164. Phcendgamous, or phanerdgamous : hav- ing manifest flowers, 69. Phoenogamous or Phanerogamous Plants, 69, 369, 375. Phalanges: bundles of adelphous or clustered stamens. Phordnthium : the receptacle of Com- positae. Phrymacese, 450. Phyrdlogy : same as Algology. Phylla: leaves, 274. -phyllous : leaved, as 3-phyllons, three-leaved, &c. Phyllodtneous : bearing or resembling a P/iyllddium : a dilated petiole taking the place of a blade, 170. Phylhtdxis, or phyllatdxy, 133. Physiological Botany, 14, 17. Phytelephantere, 485. Phytdgraphy : descriptive Botany. Phytolaecacece, 463. Phytdlogy : Botany in general. Phyton : a simple plant-individual, or plant-element, 96. Phytdtomy : vegetable anatomy, 14. Pileale, pileiform : like a cap or Pilots, 507. Pileorhiza : the cap of a root, as found in some aquatic plants ; fig. 102. Piltferous : bearing or tipped with hairs [pili). Pilose ; hairy, as distinguished from woolly or downy ; i. c. distinct and straight, but not rigid hairs. Pilosity : hairiness. Pimento, 418. Pine-apple, 492. Piney Tallow, 400. Pink-root, 435. Pinna : one of the primary divisions of a pinnatcly compound leaf, 164. Pinnate, pinnated: a compound leaf with leaflets arranged along the sides of a common petiole ; 163, fig. 288-290. Pinnately cleft, lobed, parted, &c, 160. Pinnately 3-plurifoliolate, &c, 164. Pinnately veined, 155, 160. Pinndtijid: pinnately cleft; fig. 261. Pinndtisect: pinnately divided; fig. 263. Pinnule : a secondary division of a pin- nately compound leaf. Piperacese, 469. Piperine, 469. Pisiform : pea-shaped. Pistachio-nut, 406. Pistil: the ovule-bearing organ of a flower, 223, 287. Pistillate : furnished with pistils, or pis- tils only, 261. Pistillidium, 337. Pitch, 480. Pitchers: see Ascidium ; 169, 387, fig. 299-301. Pitcher-shaped : campanulate or tubular, but with a narrower mouth. Pith, 118. Pits, 37. Pitted : marked with small depressions. Pitted tissue, 45. Placenta : the place or part of the ovary which bears the ovides or seeds, 289. Placentation : the arrangement of pla- centa?. Placentiferous : bearing the placenta;. Placdntiform : nearly the same as quoit- shaped. Plaited: see Plicate, 273. Plane: flat. Plantaginacea3, 444. Platanacea;, 476. Platycdrpous : broad-fruited. Pleio-, in Greek derivatives : full of, or many ; as Pleiospermous : many-seeded, &c. Pleure'nchyma : woody tissue, 41. Pleurorhizal : embryo with the radicle lying against the side or edge of the cotyledons ; same as accum- bent. Plicate, plicative : thrown into longitu- dinal plaits (plicie); folded, 144, 273. Plum, 415. Plumbaginacea;, 444. Plumose : feathered ; when bristles, &c. have fine hairs on each side like the plume of a feather, as the pap- pus of Thistles, &c. ; fig. 890. Plumule : the bud or growing point of the embryo above the cotyledons, 71, 324. Pluri-, in words of Latin origin : sev- eral, at least more than one ; as Plurifidrous : several-flowered. Plurifdliolate : bearing several leaflets. GLOSSARY AND INDEX. 545 Plurildcular : several-celled. Pdculiform : deep cup-shaped. Pod: a dry dehiscent fruit, 315. Pddosperm: seed-stalk, 297. Podostemacea3, 471. Pointless : see Muticous. Poiniletted: same as Apiculate. Polemoniacece, 453. Pollen : the contents of the anther, 223, 285. Pollen-tube, 286, 302. Pollinia : pollen-masses, 286, 489. Polliniferous : bearing pollen. Poly-, in Greek compounds : numerous. Polyadelphia, 513. Polyadelphous : having the filaments in several sets, 280. Polyandria, 512. Polydndrous : with numerous stamens, especially when inserted on the receptacle, 242, 280. Polydnthous : many-flowered. Polycdrpic: fruiting many times, i. e. year after year; perennial. 101. Polyce'phalous : bearing many heads. Polycladous : much-branched. Polycdccous : of several cocci. Polycotyle'donous : having several cotyle- dons, 79, 326. Polygalacese, 411. Polygamia, 513, 515. Polygamous : having both perfect and separated flowers, 262. Polygonacea?, 465. Polygonous : many-angled. Polygyria, 515. Polygynous: with numerous pistils or styles, 287. Polymerous: formed of many members. Polymorphous : various in form. Polypeta/ous : having distinct petals, 249, 275. Pdlyphore ; a common receptacle of many carpels, as in Strawberry. Polyphyllous : many-leaved or several- leaved, 275. Polypodiacea;, or Polypodinese, 501. Polyrhizal : many-rooted. Polysepalous : of two or more distinct sepals, 249, 275. Polyspe'rmous : many-seeded. Polysporous: containing many spores. Polyste'monous : with many stamens. Pome: an apple, pear, &c, 312. Pomeee, or Pomacese, 416. Pomegranate, 418. Pomiferous : pome-bearing. Pomology: the department of Botany relating to fruits. Pontederiacese, 495. Porose: porous, having holes. Portulacaccaj, 396, 46* Posterior (in the flower) : next the com- mon axis, 237. Pdsticous: same as extrorse. Potato, 456, 455. Pouch: see Silicle, 317. Prafloration : same as ^Estivation, 269. Pra-foliation : same as Vernation, 143. Praimdrse : as if bitten off. Prickly : armed with Prickles, 52. Primine : outer coat of the ovule, 298. Primordial leaves, 143 ; utricle, 26. Primulaceffl, 443. Prismatic, prismatical : with flat longi- tudinal faces, separated by angles. Process : any projection from a surface. Procumbent : lying along the ground, 102. Produced : prolonged or extended. Pro-embryo, 338. Proliferous (bearing offspring) : develop- ing new branches, flowers, &c. from the older ones, or from unusual places. Prone : lying face downwards. Proper juices, 57. Prose'nchyma, 41. Prose'nthesis, 236. Prostrate : lying flat on the ground, 102. Proteaceag, 468. Proteine, 27, 53, 57, 196. Proterdnthous : where flowers arc pro- duced earlier than the leaves. Prothdllus, or protothallus, 338. Protophytes : Algae and Lichenes are so called. Protoplasm, 26, 53, 57, 196. Priiinate, priiinose : as if frosted over. Pi-uniform : plum-shaped. Pseudo-bulb : a kind of corm,.as of epi- phytic Orchidaceae. Pseudo-parasitic: same as epiphytic. Pterocdrpous : wing-fruited. Pteroid: wing-like. Pube'scent : clothed with soft or downy hairs, or pubescence. Puqidniform : dagger-shaped. Pulque, 491. Pulse, 413. Pulveraceous, or pidve'rulent : dusty or powdery on the surface. Puh'inate : cushioned. Pulvinus (a cushion) : an enlargement at or below the base of a leafstalk. Pumpkin, 423. Punctate: dotted as if by punctures. Pungent : pricking ; rigid-pointed. Piistulate : blistered. Putdmen : the stone or shell of a drupe, 310, 312. Pyre'nce : the stones of small drupes ; same as nucules. 546 GLOSSARY AND INDEX. Piriform : pear-shaped. Pyroleas, or Pyrolacese, 440. Pyxidate : furnished with a lid, like a Pyxidium, or pyxis : a pod opening by a lid; 317, fig. 575, 588, 950, &c. Quadrangular : four-angled. Quadri-, in Latin compounds : four. Quadrifarious : in four vertical ranks. Quddnfid : four-cleft. Quadr [foliate : four-leaved. Quadrifoliolate : of four leaflets. Quadrijugate : four-paired. Quadripartite : four-parted. Quandang-nuts, 460. Quassia, 405. Quaternary : consisting of four, 239. Quaternary products, 53, 57, 196. Quate'rnate: in fours. Quercitron, Quercine, 476. Quin-, in Latin compounds : five in number. Quinary : consisting of five, 234, 239. Quinate : in fives. Quince, 416. Quincuncial: five-ranked; in a quincunx, 135, 270. Quinine, Quinia, 57, 433. Quinquefarious : five-ranked. Quinquefoliate : five-leaved. Quinquefdliolate : of five leaflets. Quinquelocular : five-celled. Quinquina Bark, 433. Quintuple : dividing into five parts. Quintuple-ribbed, or Quintupli-nerved, 156. Race: a variety perpetuable by seed, 356. Raceme : an indefinite inflorescence with single pedicelled flowers arranged along a prolonged axis; 211, fig. 307. Racemiferous : bearing racemes. Race'miform: resembling a raceme. Racemose : bearing or resembling ra- cemes. Rachis : see Rhachis. Radial : belonging to the border or ray. Radiate, radiant : spreading from or arranged around a centre ; having rays. Rddiated-veined, 156. Radical: relating to the root (radix). Radical leaves : those apparently spring- ing from the root, 143. Rddicant: rooting. Radicel: a diminutive root or rootlet. Radicifldrous : flowering from the root, or apparently so. Radiciform : appearing like a root. Radicle : a diminutive root ; the part of an embryo below the cotyledons, 71, 324. Radii: rays. Rafflesiaceoe, 463. Ramal, or rameal : relating to branches, 143. Rame'nta, raments : thin chaffy scales in place of hairs. Ramentdceous : bearing raments, as the stalks of many Ferns. Ramification, 97. Rdmijlorous : flowering on the brandies. Ramose: bearing branches (rami) ; branchy.* Rdmulose : bearing many branchlets (rdmuli). Ranunculaceae, 380. Raphe : see Rhaphe. Raphides : crystals in plants, 59 Rare : thinly set ; sparse or few. Raspberry, 416. Ray : the marginal flowers of a head, when different from the rest, 436 ; the branches of an umbel, &c. Ray -flower, 436. Receptacle of the flower, 224, 266. Receptacle of inflorescence, 211, 215. Recess: same as sinus. Re'clinate, reclined: falling or turned downwards. Re'clinerved : parallel-veined. Rectiserial: in rectilinear ranks, 141. Recurved: curved, especially curved backwards. Reduplicate, reduplicative, 273. Refle'xed : bent downwards or back- wards. Refracted: suddenly bent backwards. Regular : the members alike in size and form, 239, 277. Reniform: kidney-shaped ; same as round-heart-shaped, but the breadth greater than the length ; fig. 245. Repdnd: bowed, the margin obscurely sinuate, 159, fig. 257. Repent: same as creeping, 102. Replicate : folded back. Re'plum (a door-case) ; the frame-like placenta? of Papaveracese, &c. from which the valves of the pod fall away in dehiscence. Reproduction, 20, 21, 61 ; — in Cryptoga- mous plants, 330. Reproductive organs, 70. Reptant : same as repent. Resedacese, 391. Resins, 195. Respiration, 178, 199, 202. Restiacese, 496. Resiipinate : underside up, or having that appearance. Reticulated: netted, 154. GLOSSARY AND INDEX. 547 Reticulated ducts, 46. Retinaculum : a stay or holdfast : ap- plied to the processes bearing the seeds of Acanthaceas, &c. Re'tinerved : same as reticulated. Retroairved : same as recurved. Retrofle'xed : same as reflexcd. Retrofracted : same as refracted. Retrorse : backwards, directed back- wards. Retrove'rted : turned upside down. Refuse : slightly notched at a rounded apex; 162, fig. 272. Re'volute, resolutive : rolled backwards, 144. Rhachis (back-bone) : the axis of a spike, &c, 211. Rhamnaeea?, 408. Rhaphe of an ovule or seed, 299, fig. 529, r. Rhatany, 412. Rhizdnthous : root-flowered; as when a flower (like Raffiesia, fig. 150), or a cluster of flowers, &c. without green foliage (like Beech-drops), is parasitic by what answers to roots, on some foster plant. Rhizocdrpous (root-fruiting) : having a perennial root. Rhizdma: rootstock, 106. Rhizomorphous : root-like. Rhizophoraceas, 419. Rhodospermeas, 509. Rhombic : rhomb-shaped. Rhomboidal : approaching a rhomboid in form. Rhubarb, 466. Rib : a strong nerve or part of the frame- work of a leaf, &c, 145, 155. Ribbed: when strong nerves or ribs run lengthwise through a leaf, &c. Ricciacese, 504. Rice, 498. Rimose: with chinks or clefts (rimce). Ring of Ferns, 501 ; of Mosses, 503. Ringent : grinning ; when a bilabiate corolla is open, 278. Riparious : along water-courses. Root, 79. Root-hairs, 81. Rootlet : a very small root, or ultimate branch of a root. Rootstock : same as rhizoma, 106. Rosacea?, 415. Rosaceous : rose-like, 276. Rdstellate : diminutive of rostrate. Rosteilum : a little beak. Rdstrate : beaked, bearing a Rostrum : a beak-like projection. Rdsular, or rosulate : shaped like a ro- sette. Rotate : wheel-shaped ; 278, fig. 454. Rotation in cells : see Cyclosis, 31. Rotund, rotundate : of rounded outline. Rough : see Scabrid or Scabrous. Rubescent, rubicund : reddish or rosy. Rubiaceoe, 431. Rubiginose : rusty reddish. Ruderal : growing in rubbish. Rudimentary : imperfectly or incom- pletely developed. Rufescent : approaching to Rufous : brown-red. Rugose: wrinkled (ruga, a wrinkle). Ruminated (albumen) : penetrated with holes or channels ; 323, 383, fig. 658. Runcinate : saw-toothed, the teeth turned backwards, 161, fig. 279. Runner, 102. Running, 102. Rupestrine : growing naturally on rocks. Ruptile : bursting irregularly. Rusty: see Ferrugineous. Rutacea;, 405. Rye, 498. Sdbuline, or sdbulose : growing in sand. Saccate, sacciform : sac-shaped, 278. Sac of the amnios, 304. Saffron, 491, 437. Sagittate : arrow-headed, or arrow- shaped ; lanceolate with a lobe a$ the base on each side pointing backwards ; fig. 252. Sago, 481, 485. Salep, 489. Salicaceae, or Salicinia?, 478. Salicine, 478. Saline, salsuginous : growing in salt places, or impregnated with salt. Salver-shaped: tubular and the border spreading flat at right angles to the tube ; 277, fig. 457. Salviniea?, 502. Samara : a key or winged indehiscent fruit, 314, fig. 577, 578. Sdmaroid: resembling a samara. Sambuceas, 431. Sandal-wood, 414, 469. Santalaceai, 468. Sap, 53, 190. Sapindacece, 409. Sap-green, 408. Sapodilla Plum, 443. Sapotaceoe, 443. Sap-wood, 35, 124, 126. Sdrcocarp : the fleshy part of a drupe, 310, 312. Sarmentdceous : bearing or resembling Sarments : runners or long and flexible branches. Sarraceniacese, 387. Sarsaparilla, 493. 548 GLOSSARY AND INDEX. Saururaceas, 469. Saw-toothed: same as Serrate. Sdxatile : living in rocky places. Saxifragacea;, 424. Scabrate, scabrid, or scabrous : rough to the touch. Scaldriform : ladder-shaped, or barred. Scalariform ducts, 46. Scales : any thin scale-like appendages ; usually degenerated leaves, 105. Scalloped: same as Crenate. Scaly : furnished with scales, 95, 191. Scammony, 455. Scandent : climbing. Scape: a flower-stalk rising from the ground or near it, 220. Scdpiform, or scapoid : resembling a scape. .Scar : see Leaf-scar and Hilum. Scdriose, or scdrious : thin, dry, and membranaceous. Scattered : either sparse, or without ap- parent symmetry of arrangement. Schizandreae, 382. Scion : a shoot, especially one used for grafting. Sciuroid: like a squirrel's tail. Sclerantheaj, 396. Scle'roqen : same as Lignine, 36. Scobiform, or scobicular: like sawdust. Scorpioid : coiled round like a scorpion, as the branches of the cyme of Heliotrope. Scrobiculate : pitted. Scrophulariacece, 448. Scrdtiform : pouch-shaped. Scurf: minute or bran-like scales on the epidermis, 52. Scutate, scutiform : shield-shaped. Scute'lliform : shaped like a platter (scu- tella). Secretions, 51. Sectile : divided into portions. Secund : all turned to one side of an axis. Secundine : the second coat of an ovule, 298. Seed, 70, 320. Seed-vessel, 308. Segment : one of the divisions or lobes of a leaf or other organ ; 159, 275. Segregate : kept separate. Semi-, in Latin compounds : half. Semi-adherent : the lower half adherent. Semi-amplexicaul : half-clasping. Semicordate: hah heart-shaped (divided lengthwise). Semi-double : half-double. Semi-floscular : when the flowers of a head are ligulate. Semilunar, or semilunate : like a crescent or half-moon. Seminal : relating or belonging to the seed. Seminiferous : seed-bearing. Semiorbicular : half-round. Semioval : half of an oval, and Semiovate : half of an ovate figure, di- vided longitudinally. Semisagittate : arrow-headed with one lobe wanting. Semiseptate : a partition reaching partly across. Semiterete : half-cylindrical. Sempervirent : evergreen. Senna, 414. Sensitive plants, 345. Sepal: a calyx-leaf, 222. Se'paline, sepalous : relating to sepals. Se'paloid : resembling a sepal. Separated flowers : the stamens and the pistils occupying separate blossoms, 261. Septate: with a partition (septum). Septicidal, or se'pticide : dehiscent through the partitions, i. e. by the lines of junction; 316, fig. 582, 584. Septiferous : bearing a partition. Septifragal : where the valves separate from the dissepiments, 317. Septum (plural septa) : a partition of any kind, 316. Se'rial, or striate : arranged in rows. Sericeous : silky. Series: rank. Serotinous : flowering or fruiting late. Serrate: beset with teeth pointing for- wards, like those of a saw, 159, fig. 254. Serratures : the teeth of a serrate body. Serrulate : serrate with fine teeth. Sesameae, 447. Sdssile (sitting) : not stalked, 145, 211, 281. Seta : a bristle, or bristle-like body, 52. Setaceous, setiform : like a bristle. Setigerous : bristle-bearing. Setose : bearing or abounding with bris- tles. Se'tula : diminutive of Seta. Se'tulose : bearing minute bristles. Sex : six ; as in Sexangular : six-angled. Sexfarious : six-rowed. Sexpartite : six-parted, &c. Shaggy : see Villous. Sheath : a tubular body, enclosing or surrounding some other ; as the base of the leaves of Grasses ; 1 7G, fig. 237. Sheathing : forming a sheath ; see Va- ginate. Shields : see Apothecia, 506. GLOSSARY AND INDEX. 549 Shield-shaped: see Peltate, 158, fig. 248, 681. Shoot : any fresh branch. Shrub, shrubby, 101. Sigillate : as if marked with the impres- sion of a seal, as in Solomon's Seal, fig. 168. Sigmoid : curved like the Greek sigma, or letter S. Signs used in Botany, 517. Sileneas, 395. Silicle : a pouch, or short pod of Cru- ciferaj, 317, fig. 703. Siliculosa, 515. Siliculose: having or resembling a sili- cle. Silique : a long pod of Cruciferae ; 317, fig. 589. Siliquosa, 516. Siliquose: like a silique. Silk-cotton, 399. Silky : clothed with fine, appressed, and glossy hairs, producing a satiny surface. Silver-berry, 468. Silver-grain, 120. Simarubacese, 405. Simple : of one piece or rank. Simple fruits, 309, 311; leaves, 162; pistil, 288. Sinistrdrse : turned to the left. Sinuate : strongly wavy on the margin, with alternate convexities and con- cavities ; 159, fig. 258. Sinus : a re-entering angle or recess. Slashed : same as Laciniate. Sleep of plants, 344. Smilaceas, 492. Smooth : not pubescent or hairy, or else (and more strictly) not rough. Snake-root, 412, 462. Soap-berry, 410. Soboliferous : bearing shoots (sobofes). Social (plants) : growing gregariously. Solanacese, 456. Solitary : single ; alone. Soluble : separating into parts. Sore'diate : bearing little patches on the surface. Sorose : heaped, or bearing. Sorosis : a fleshy multiple fruit, like a mulberry. Sori (sing, sorus) : heaps or patches, as those of the spore-cases of most Ferns, called in English fruit-dots, 501. Spadiceous : bearing a Spadix : a sort of flesby spike, 213. Span : the length spanned between the thumb and little finger ; seven or eight inches. Sparse : scattered and generally scanty. Spathdceous : bearing a Spathe : the enveloping bract of a spa- dix, 213. Spdthulate, or spatulate: shaped like a druggist's spatula. Special directions, 341. Species, 19, 354. Specific : relating to species. Spe~rmaphore : a name for the placenta, or the funiculus of the seed. Spermatozoids, 334. Spermic, or spermous : relating to the seed. Spe'rmoderm : the outer seed-coat, 320. Spicate: relating to or disposed in a spike. Spiciform : spike-like. Spicula : a spikelet. Spike: a prolonged indefinite inflo- rescence with sessile flowers, 212. Spikelet: a diminutive or secondary spike ; the ultimate flower-clusters of Grasses. Spikenard, 435. Spindle-shaped, 84, fig. 138. Spine, 104, 167. Spinescent: tipped with a spine, 104. Spinose: spiny, 104. Spinidose: bearing diminutive spines. Spiral : as if wound round an axis. Spiral arrangement of leaves, 134. Spiral markings on cells, 39. Spiral vessels or ducts, 46. Spireae, 416. Spithamceous : a span high. Spongioles, or spongelets, 80. Spongy : of the texture of sponge. Spontaneous movements, 340, 347. Sporadic : widely dispersed. Sporangium : a spore-case, 337, 500, &c. Spore: the body in Cryptogamous plants which answers to the seed in the Phajnogamous, 61, 70, 331. Spore-case, 337. Sporiferous : spore-bearing. Spdrocarp : a kind of sporangium, 502. Sports, 356. Spdrule : a spore, or small spore. Sporulifcrous : bearing sporules. Spumescent, spumose : froth-like. Spur: any tubular projection, 278. Spurred: bearing a spur, 278. Spiamate, squamose, squamiferous : fur- nished with scales (squamce). Squdmellate : with or resembling minute and narrow scales (squamelloz, 497). Squdmiform : scale-shaped. Squdmidiform : like a small scale, or Squdmula, 497. Squdmulose : covered with small scales. Squairose: where scales, small leaves, or other bodies, spread widely from 550 GLOSSARY AND INDEX. the axis on which they are crowded. Squdrrulose : diminutive of Squarrose. Squash, 423. Squills, 493. Stalked : furnished with a stalk, stem, or any lengthened support. Stalked (/lands, 52. Stalklet: a diminutive or secondary stalk. Stamen : the fertilizing organ of a flow- er, 223. Stdminate, or stamineal: relating to the stamens. A staminate flower has no pistils, 261. Staminiferous : bearing stamens. Staminddium: an altered and sterile sta- men, or a body occupying the place of a stamen. Standard: the posterior petal of a pa- pilionaceous corolla, 253. Staphyleacece, 409. Star-apple, 443 . Starch, 54, 193. Staticese, 445. Station: the locality or kind of situa- tion in which a nlant naturally grows. Stellatae, 432. Stellate: starry, star-shaped; arranged in rays, like the points of a star. Stellate hairs, 52. Ste'llulate : diminutive of Stellate. Stem, 91. Stemless : having no obvious stem, 91. Slemlet : a diminutive stem ; the first internode of the plumule. Sterculiacere, 399. Sterigma : the adherent base or down- ward prolongation of a decurrent leaf. Sterile: barren. Sterile flower : one having no pistils, 261. Sterile stamens or Jllaments : those des- titute of anthers, or with the anther imperfect, 281. Stigma : the part of a pistil which re- ceives the pollen, 223, 287. Stigmdtic, or stigmatose : relating to or bearing the stigma. Stings, stinging hairs, 52. Stipe (stipes) : a stalk of an ovary (267), of a Mushroom (507), and the leaf-stalk of a Fern. Slipel : the stipule of a leaflet ; 1 7 1 , fig. 286. Stipellate: furnished with stipels, 171. Stipitate: having a stipe, 267. Stipitiform : shaped like a stipe. Stipiddceous, stipular : belonging to or resembling stipules. Stipulate, stipuled: possessing stipules, 171. Stipule: an accessory part of a leaf, one on each side of the base, 145, 170. Stock, 355. Stole, stolon: a rooting branch, 102. Stoloniferous : bearing stolons. Stoma (plural stdmata), stomate: a breathing-pore, 52, 150. Stomatiferous : bearing stomates. Stone : the endocarp of a drupe. Stone-fruit, 312. Stool : the plant from which layers arc propagated. Storax, 425, 442. Stramineous : straw-like. Strangulated : irregularly contracted. Strap-shaped: see Ligulate. Stratum : a layer. Strawberry, 416. Striate : marked with longitudinal streaks or furrows (strioz). Strict : very straight or close, or very upright. Strigillose : same as Strigose. Strigose : clothed with sharp and stout close-pressed hairs or scale-like bristles (strigce). Strobildceous : relating to, or resem- bling a Strdbile : the cone of a Pine, &c., 319. Strobiliferous : bearing strobiles. Strombuliferous : spirally twisted, like a corkscrew or a strombus. Strdphiole : same as a Caruncle, 322. Structural Botany, 14. Strumose : swollen on one side, bearing a struma or wen. Strychnine, 57, 434. Stupose: tow-like. Style : a columnar or slender part of the pistil above the ovary, 223, 287. Styliferous : style-bearing. Styliform : style-shaped. Stylopddium : an enlargement or fleshy disk at the base of a style, as in Umbelliferse. Styraceas, 442. Sub-, as a prefix, means somewhat, or slightly ; as Subacute : somewhat acute. Subclass, 362. Subcordate ; slightly heart-shaped, &c. Siiberose : of a corky texture. Subgenus, 361, 362. Submerged : growing under water. Suborder, 361. Subspecies : a marked variety. Subtribe, 361. Subterranean : growing beneath the sur- face of the ground. GLOSSARY AND INDEX. 551 Subulate, subidiform : awl-shaped ; nar- row, and tapering to a sharp rigid point, as the leaves of Juniper, &e. 166. Succise : as if cut off at the end. Succose, succulent: juicy. Siiccubous: the apex of each leaf cov- ered by the base of the next, as in Jungermannia. Succulent leaves, 166. Sucker, 102. Suffrute'scent : slightly shrubby, 101. Suffnitex : an undershrub. Suffriiticose: low and shrubby, or shrub- by at the base, 101. Sugar, 53, 193, 194. Sulcate : longitudinally grooved. Supe>--, above ; as Super