EDUCATION DEPT SECOND BOOK OF BOTANY, A PRACTICAL GUIDE OBSERVATION AND STUDY OF PLANTS. BY ELIZA A. YOUMANS, AUTHOR OP "THE FIRST BOOK OF BOTANY," EDITOR OF HENSLOW'S BOTANICAL CHARTS. NEW YORK: D. APPLETON & COMPANY, 549 & 551 BROADWA.Y. 1873. E<* ^ ENTERED a$cfc$ng't* ^ct'pV^OEgress, to the yfrar 1873, by ''*' ' '' J.' APPEETON In the ofllce of the Librarian of Congress, at Washington. EOUCATtON INTEODUCTION. THE First Book of Botany, for the use of beginners, was designed to cultivate the observing powers of the young by making plants themselves the regular objects of study. It was published three years ago, and adopted by numerous schools, and, upon trial, it proved so satisfactory that there have been frequent and urgent calls for a more advanced book upon the same method. After much delay, which I regret, but have been unable to avoid, a Second Book, carrying out the plan, is now ready, together with an instructive series of Botanical Charts, which will be helpful to both teachers and pupils. In the preface to the First Book, and in an Essay reprinted at the end of the present volume, I have stated the purpose that led to these publications : the present extension of the method affords a suitable occasion for presenting some further considerations in illustration of it. I had two objects in view, one relating to the subject of Botany, and the other to the mental cultivation of the young. As regards the science itself, it seemed to me to be very badly dealt with in the schools. In many it is not taught at all, and in others it is regarded as a kind of superfluous side- study, of such secondary importance that it matters little in what way it is treated. And so it is subordinated to the school routine, and pursued in a hurried and desultory manner, by books and recitations, and by memorizing second-hand informa- tion. It is perfectly well known that, in institutions of all grades, students often " go through " the botanical text-books 961676 2 INTRODUCTION. Without giving; atfy attention whatever to the objects they de- jserjbe';' or,, if .they, do so-gt all, it is generally in an incidental 'ah'd' ,Jtatitfn!a|l ;wa^ 7 V^)erhaps by attacking the most complex part of the plant first, and picking flowers to pieces, so that the pupil may quickly indulge in the shallow pedantry of giving them their technical names. All this is unjust to the science. Like arithmetic, Botany is only to be acquired by first master- ing its rudiments. And as, in arithmetic, the student is com- pelled to exercise his mind directly upon numbers, and work out the problems for himself, so in Botany, if worth pursuing at all, it should be studied in its actual objects. The char- acters of plants must become familiarly known by the detailed and repeated examination and accurate description of large numbers of specimens. The pupil must proceed step by step in this preliminary work, digesting his observations, and mak- ing the facts his own, until he becomes intelligent in regard to all the common varieties of plant forms and structures. It is because the text-books of Botany hitherto in use fail to provide for and to enforce this thoroughness of introductory study of the characters of plants fail in the very groundwork of the subject that the present plan of study has been prepared. But, it will be asked, " Is botanical science, after all, worth acquiring in so painstaking a way ? " This is an important question, and brings me to the higher purpose I had in the arrangement of these books. The uses of Botany are by no means to be measured by the interest or utility of the knowl- edge of plants. A thorough acquaintance with the science will be serviceable on its own account through life ; but its merit is that it leads to an end beyond itself: it has great value as a means of mental cultivation. That branch of Natu- ral History which treats of the vegetable kingdom ought to be, and can be, made corrective of a fundamental defect in our educational system. This deficiency is a lack of any provision for thoroughly exercising the minds of the young upon natural objects. Our plan of general education includes not a single subject that can secure the mental advantages arising from the direct and systematic study of Nature. We do a great deal in the way of " mental discipline," but the order and truth of things around us are not allowed to contribute to it. We train the faculty of calculation and drill the memory in lesson- INTRODUCTION. 3 learning, but the realities of Nature find no place at our schools as means of mental unfolding for training in observation, and for working the higher faculties of reason and judgment upon natural things. In short, for calling out the more important powers of the mind, by actual exercise upon the objects of sur- rounding experience, our educational system makes no pro- vision whatever. Neither reading, writing, arithmetic, gram- mar, nor geography, brings the mind into contact with Nature at all ; and even the sciences of physics, chemistry, physiology, and botany, are usually acquired from books, and with so little regard to the real objects of which they treat, that as means of mental improvement they are of very slight service. That modern education, in all its gradations, is profoundly deficient in this respect, has long been recognized and de- plored by the most enlightened educators. Dr. Whewell, for example, late Master of Trinity College, Cambridge, in one of his able works upon Education, says: "The period appears now to be arrived when we may venture, or rather, when we are bound to endeavor, to include a new class of fundamental ideas in the elementary discipline of the human intellect. This is indispensable if we wish to educe the powers which we know it possesses." Again, he remarks: "There are perverse intellectual habits very commonly prevalent in the cultivated classes, which ought, ere now, to have been corrected by the general teaching of Natural History. We may detect, among speculative men, many prejudices respecting the nature and rules of reasoning which arise from pure mathematics having been so long and so universally the instrument of intellectual cultivation." And again: "In order that Natural History may produce such an effect, it must be studied by the inspec- tion of the objects themselves, and not by the reading of books only. Its lesson is that we must, in all cases of doubt or ob- scurity, refer, not to words or definitions, but to things. The Book of Nature is its dictionary ; it is there that the natural historian looks to find the meaning of the words which he uses." * To gain the mental benefits of the study of Natural History here proposed, the pupil's attention requires to be concen- trated upon a limited portion of it, which is to be thoroughly i " Novum Organum Renovatum," p. 170. 4 INTBODUCTION. mastered, and Botany presents special and eminent advantages for this purpose. He is brought face to face with Nature, and his first and constant work is the observation of phenom- ena; not merely looking with the eye, but recognizing with the 'mind. The science consists of a comprehensive system of organized and closely-dependent truths, which it is the business of the student to trace out and rediscover for him- self. From the beginning he is engaged in comparing his observations, and reasoning upon his facts. As nothing can be done without terms, to mark his discriminations, he commences their use at the outset ; and, as the language of Botany is more precise than that of any other science, there is constant drill in accuracy of description. As he ex- tends his familiarity with plant characters, the work of com- parison and grouping calls for a higher exercise of thought. Finally, in classification, which is the goal of all his prepara- tory study, he engages with problems of increasing complexity the grouping of plants by masses of resemblances distinc- tion of kinds and classes of things by likenesses and differ- ences of unequal values, and the formation of groups in subor- dination to each other all of which involve the highest ex- ercise of judgment. Thus, the thorough study of Botany as a branch of Natu- ral History, and as a means of education, not only " communi- cates precision, clearness, and method to the intellect, through a great range of its operations," but its discipline is corrective of the most common defects of education, and is eminently applicable in forming judgments upon the ordinary affairs of life. Carelessness in observation, looseness in the application of words, hasty inferences from partial data, and lack of method in the contents of the mind, are common faults even among the cultivated, and it is precisely these faults that the study of botanical science, by the method here proposed, is calculated to remedy. That the habit of systematic arrange- ment, in which the study of botanical classification affords so admirable a training, is equally valuable in methodizing all the results of thought, is testified to by one of the most intel- lectual and influential men of our time, Mr. John Stuart Mill. He was a regular field botanist, and cultivated the subject with a view to its important mental advantages ; and his INTRODUCTION. 5 great work on logic took a form which, could not have been given it if the author had not been a working naturalist as well as a logician. In the second volume of his <* System of Logic "Mr. Mill says: " Although the scientific arrangements of organic Nature afford as yet the only complete example of the true principles of rational classification, whether as to the formation of groups or of series, these principles are applicable to all cases in which mankind are called upon to bring the various parts of any ex- tensive subject into mental coordination. They are as much to the point when objects are to be classed for purposes of art or business, as for those of science. The proper arrangement, for example, of a code of laws, depends on the same scientific conditions as the classifications in natural history ; nor could there be a better preparatory discipline for that important function than the study of the principles of a natural arrange- ment, not only in the abstract, but in their actual application to the class of phenomena for which they were first elaborated, and which are still the best school for learning their use." If, therefore, the object of education is the completest cul- tivation of the powers of the mind, botanical science evidently has a very strong claim to a regular and leading place in our scheme of school-studies. But it will be a grave mistake to suppose that its benefits can be secured by the mere use of text- books, however full and valuable the information they con- tain. Nor are they to be gained by the casual examination of plants, nor by the analyses of a few flowers, with the aid of keys and dictionaries, nor in the limited time usually allotted to the subject. The study must be commenced early and pur- sued steadily by the method of direct observation, until its elementary facts and principles are made entirely familiar. It is the claim of the First and Second Books of Botany that they lead the pupil over this indispensable ground, and, if faithfully followed, they will lay the solid foundation of the science, and will contribute to that desirable bent and habit of the intellect which natural-history studies are best calculated to impart. They are not intended to supersede the regular treatises upon the science, but to supplement them and prepare for them. They are guides to self-education, and are adapted for use in school or out, by teachers and mothers, whether D INTRODUCTION. they know any thing of the subject or not, and by pupils with- out any assistance at all. A large amount of time will not be required, but the exercises should be so frequent and regular as to keep the subject prominently in mind, and maintain the interest in vegetable forms. The Second Book begins where the First left off. The use of magnifying-glasses and microscopes is commenced, and the work now becomes more close and thorough. As soon as the more important features of the flower are known, the pupil is introduced to the leading principles by which plants are arranged, and set to making groups of those that most nearly resemble each other in important characters. He is here called upon to do his own thinking, and to form opinions as to the amount of resemblance between different plants. He has to decide whether a certain group of characters presented by his specimen is most like one or another group presented by other plants, and this leads on to the comparison and estimate of the relations of different groups with each other. It is thus that the discipline of the judgment and reason begins to be secured at an early stage of the study, and is continued with more and more completeness as it goes on. I am much indebted to the kindness of Mr. George C. Woolson for having carefully revised the proofs of the present volume, and have also to thank Prof. George Thurber for valu- able suggestions, both in regard to the present work and the revised edition of Prof. Henslow's Charts. E. A. T. NEW YOKK, June, 1873. HENSLOW'S BOTANICAL CHAETS. LARGE colored diagrams for teaching botany are so valua- ble that, in the absence of any publications for the full and sys- tematic illustration of the subject, lecturers have been in the habit of roughly preparing them for class-room use. Recog- nizing this want of schools and students, Prof. J. S. Henslow, the eminent English botanist, who has done so much to sim- plify and improve the elementary teaching of the subject, took the matter up ; and one of the last works of his life was to prepare a set of botanical charts for educational purposes. There was perhaps no other living man so competent to the task, as his thorough knowledge of the science, his experience as a lecturer to the Cambridge students when he was profess- or in that university, and his subsequent teaching of the par- ish children at Hitcham, qualified him to meet the wants of all grades of learners. He prepared a series of nine large sheets, and, as their publication was expensive, it was undertaken as an important educational work by the Science and Art Depart- ment of the English Educational Council. " Henslow's Botan- ical Diagrams " have had a high reputation for their scientific accuracy, their completeness of illustration, their judicious se- lection of typical specimens, and their skilful arrangement for the purposes of education. In bringing out a method of ele- mentary botany, which desires to give every advantage in its thorough acquisition, the author of the First and Second Books felt the need of large colored diagrams, and, as there is nothing of the kind in this country, while the importation of Henslow's series is costly, her publishers were induced to incur the very considerable expense of publishing a revised edition of the English charts. This revision and reissue were the more necessary, as the foreign edition has one very serious defect ; it was compressed into so small a space that the figures often overlapped, producing an indistinct and confused effect. 8 HENSLOW's BOTANICAL CHARTS. The American edition consists of six large charts, and the pictures are spread over twice the original area, giving much greater distinctness and a very attractive aspect to the series. Several American specimens have been substituted for English species which do not occur in this country, and illustrations of the classes of flowerless plants have been added, for which Prof. Henslow did not seem to find room. In the plan of the charts, the plant is first represented of its natural size and colors ; then a magnified section of one of its flowers is given, showing the relations of the parts to each other. Separate magnified views of the different floral organs, exhibiting all the botanical characters that belong to the group of which it is a type, are also represented. The charts contain nearly five hundred figures colored to the life, and which represent twenty-four orders and more than forty spe- cies of plants, showing a great variety of forms and structures of leaf, stem, root, inflorescence, flower, fruit, and seed, with numerous incidental characters peculiar to limited groups. All these are so presented as to be readily compared and con- trasted with each other. The charts are not designed to supersede the study of plants, but only to facilitate it. Their office is the same as the illustrations of the book ; but they are more perfect, and bring the pupil a step nearer to the objects themselves. Many plant characters are so minute that they are difficult to find, and much is gained by referring first to the enlarged and col- ored representations. Besides this special assistance in object-study, the charts will be of chief value in bringing into a narrow compass a complete view of the structures and relations of the leading types of the vegetable kingdom. In fact, they are designed to present, fully and clearly, those groupings of characters upon which orders depend in classification ; while in several cases of large and diversified orders the characters of leading genera are also given by typical specimens. The charts will thus be found equally valuable to the beginner, the intermediate pu- pil, and the advanced student. A Key accompanies the charts, and they can be used with any botanical text-books, and dur- ing the season of plants they should be upon the walls of every school-room where botany is studied.^ TO TEACHEES. THE First Book of Botany was prepared for young children, and was made very simple and elementary, to meet the wants of juvenile minds; but it provides for a course of rudimentary observations which are not to be dispensed with by beginners of any age. As, however, pupils twelve or fifteen years old will hardly be content to go slowly over exercises adapted to young children, it may be asked how these should proceed with the First Book. In reply, it may be said, that Chap- ter IV. of the First Book, upon the flower, and which contains the first part of the flower-schedule, is the only portion of it that is indispensable to entering upon the Second Book. After this is acquired, there need be no difficulty in using both books at the same time. I would suggest that an excellent way for older pupils to familiarize themselves with the plant characters pointed out in the First Book, is at once to set about the preservation of plants, as described in Chapter XXI. of the Second Book. They may begin by putting a variety of leaves in press, having first carefully compared them with the pictures and definitions of Chapter I., First Book. At each change of the driers, the features of these leaves will be observed, and the names denoting them recalled, and by the time they are dried for mounting, it will be possible, by the aid of the last sched- ule of the chapter, to write, upon the paper holding the spe- cimen, an accurate scientific description of it. Let this be fol- lowed by the pressing of entire plants, after comparing their different organs with the examples shown in the chapters on the Stem, Inflorescence, and Roots. The attention thus drawn to their characters will be kept alive in changing them 10 TO TEACHERS. and caring for them, and the attempt completely to describe them, when dried and mounted, will go far toward fixing in the mind ideas of the forms and structures of the various organs, and the terms needed in description. But the constant temptation of such pupils will be toward haste and inadequate observation. The danger is that plants enough will not be collected, and that the parts of such as are collected will not be studied with sufficient care. The influ- ence of the teacher will therefore be constantly needed to check the too rapid passage of older pupils over that portion of Botany included in the primary book. CONTENTS. COURSE FIEST. PAGE DESCRIPTIVE BOTANY 15 CHAPTER I. THE FLOWER 15 Ex. 1. The Symmetry of Flowers 15 2. Complete and Incomplete Flowers 18 3. Essential Organs and Protecting Organs 19 4. Dichlamydeous, Monochlamydeous, and Achlamyde- ous Flowers 20 5. Perfect, Imperfect, and Neutral Flowers 22 6. Monoecious, Dioscious, and Polygamous Plants 24 7. Form of Receptacle and Insertion of Floral Organs. . 26 8. On Polyandrous Stamens 28 9. The Growing together of Stamens 30 10. The Growing together of Carpels. 32 11. Union of Floral Whorls with each other Calyx and Pistil 41 12. Union of Floral Whorls with each other Corolla. . . 43 13. Union of Floral Whorls with each other Stamens. . 46 14. The Receptacle 53 15. Appendages of the Receptacle 56 CHAP. II. COMPARING AND CLASSIFYING PLANTS. ... 59 Ex. 16. Plant Characters and Affinities 59 1Y. How to begin Classification 64 12 CONTENTS. PAGE CHAP. III. THE STAMENS 69 Ex. 18. Parts of Stamens 69 19. Number and Shape of Anther-Lobes 71 20. Dehiscence of Anther 73 21. Introrse and Extrorse Anthers 74 22. Attachment of Filament and Anther 76 23. Forms of Filaments 78 24. Structure and Forms of Pollen 79 25. Forms of Connective 81 26. General Features of Stamens. . . 83 CHAP. IV. THE PISTIL 85 Ex. 27. Kinds of Stigma 85 28. Form and Position of Styles 86 29. Kinds of Pistil 86 80. Structure of Ovaries 87 81. Placentation 91 32. Modes of Dehiscence 94 33. Direction of Ovules and Seeds 97 34. Parts of the Ovule 98 35. Kinds of Ovule 100 CHAP. V. THE FRUIT AND SEED 102 Ex. 36. The Composition of Fruit 102 37. Parts of the Pericarp 104 38. The Classification of Fruit 106 39. The Seed. Its Form and Surface 113 40. Position of the Embryo in Seeds 115 CHAP. VI FLORAL SYMMETRY, PHYLLOTAXY, PREFO- LIATION, CYMOSE INFLORESCENCE, ETC... 119 Ex. 41. Numerical Plan of the Flower 119 42. Alternation of Parts in Flowers 120 43. Leaf Arrangement. Phyllotaxis 122 44. Arrangement of Floral Leaves in the Bud. ^Estiva- tion, or Prsefloration 128 45. Cymose, or Definite Inflorescence 132 46. Duration of Floral Envelops 137 47. Surfaces . . .138 CONTENTS. 13 PAGE CHAP. VII. THE COMPOSITE 139 Ex 48. Parts of Flower-Heads 139 49. The Florets 143 50. Characters of Composite 148 CHAP. VIII. THE CRUCIFER^E, OR CROSS-BEARERS 152 Ex. 51. Characters of the Cruciferse 152 CHAP. IX. THE UMBELLIFER^E 154 Ex. 52. Structure of its Flowers and Fruit 154 53. Classification of Umbel-bearing Plants 158 CHAP. X. THE LABIATE 162 Ex. 54. Characters of the Labiates 162 CHAP. X[.-THE CONIFERS iee Ex. 55. Characters of the Coniferae 166 CHAP. XII. THE ORCHID ACE^J 174 Ex. 56. Characters of the Orchidacese 174 CHAP. XIII. THE GRAMINE^E 178 Ex. 57. Characters of the Gramineae 178 CHAP. XIV. FLOWERLESS PLANTS 184 Ex. 58. Ferns 184 . 59. Reproduction of Ferns 186 60. Mosses 189 61. Fungi 191 COURSE SECOND. VEGETABLE ANATOMY AND PHYSIOLOGY 194 CHAP. XV. THE INTERNAL STRUCTURES OF PLANTS. . . 1 95 Ex. tJ2. Cells and Cellular Tissue 195 63. Structure and Production of Cells 197 64. Vessels or Ducts, and Fibres 201 65. The Contents of Cells .208 14 CONTENTS. PAGE CHAP. XVI. THE STRUCTURE OF STEMS 212 Ex. 66. Structure of Dicotyledonous Stems. First Year's Growth 212 67. Structure of a Woody Bundle 215 68. The First Year's Growth ( Continued) 217 69. Second Year's Growth of Dicotyledonous Stems. . 221 70. Stalk of Monocotyledons 227 CHAP. XVII. THE ROOT 233 Ex. 71. True Roots and Adventitious Roots 233 72. The Minute Structure of Roots 235 73. Duration of Roots 238 CHAP. XVIII. THE LEAF 239 Ex. 74. The Minute Structure of Leaves 239 CHAP. XIX. THE PLANT IN ACTION 246 Ex. 75. Absorption of Food by Plants 246 76. Evaporation and Digestion 249 77. The Circulation of Plants 253 78. The Reproduction of Plants 255 79. The Movements of Plants 258 CHAP. XX. COLLECTING AND PRESERVING PLANTS. 268 Ex. 80. How to gather, press, and mount Plants 268 81. Labelling and arranging Plants 272 AN EXPLANATION OF THE ABBREVIATIONS USED IN THE BOTANI- CAL CHARTS 275 GLOSSARY.. . .. 277 APPENDIX. The Educational Claims of Botany 285 THE SECOND BOOK OF BOTANY, COUBSE FIRST. DESCRIPTIVE BOTANY. C H A P T E K I . THE FLOWER. WITH the present book, we are to continue the method of studying plants that was commenced with "The First Book of Botany." It is assumed that the pupil has begun the work of practical observa- tion, and made himself familiar with the general features of plants, as far as the " First Book " goes. As before, the indispensable condition of the method is-, to collect a large variety of specimens to be stud- ied. The first duty of each pupil is, to assist in gath- ering these plant-specimens, and this should be in every way encouraged, and positively required, by the teacher. EXERCISE I. The Symmetry of Flowers. Having gathered a variety of flowers, look care- fully at the pictures and definitions given in the fol- 16 THE SECOND BOOK OF BOTANY. lowing exercise. When you have found their mean- ing, you will be prepared to study your flowers. A SYMMETRICAL FLOWER is one having the same number of parts in each of its whorls, or, if not the same, then multiples of the prevailing number. FIG. 1. FIG. 2. Quinary Symmetry. Quinary Symmetry (Gray). Figs. 1 and 2 represent a symmetrical flower. It consists of five sepals, five petals, five stamens, and five carpels. It would still be symmetrical if the number of sepals, or of petals, or stamens, or car- pels, were ten, twenty, or any multiple of five. A flower with its parts arranged in twos, or multiples of two, has dimerous, or binary symmetry (Fig. 3). FIG. 8. FIG. 4. Binary Symmetry. Ternary Symmetry. THE FLOWER. IT When the parts of the floral whorls are in threes, the symmetry is trimerous^ or ternary (Fig. 4). When the parts are in fours, the symmetry is te- tramerous, or quaternary. When the parts are in fives, the symmetry is said to be pentamerouS) or quinary (Tigs. 1 and 2), If you have the botanical charts, look at the mag- nified flowers represented on them, and point out the symmetrical ones, naming the kind of symmetry they exhibit. Then examine your living specimens. These will, of course, vary with the season. We will sup- pose, for example, that you have the pea, morning- glory, violet, portulacca, buttercup, Saint- John' s- wort, hollyhock, potato-blossom, evening primrose, lily, etc. Decide which are symmetrical and which are unsymmetrical, placing the two kinds apart. Re- examine the symmetrical ones, and tell which have binary symmetry, which ternary, which quaternary, and which quinary. Binary From the Latin Mnarius, compounded of two, parts in twos. Ternary Latin ternarius, consisting of threes. Quaternary Latin quaternarius, containing four, by fours. Quinary Latin quinus, five, arranged in fives. Dimerous From two Greek words, meaning twofold and part. Trimerous From two Greek words, meaning three, or thrice, and part. TetramerousFrom two Greek words, signifying four and part. Pentamerous From two Greek words, meaning five and part. 18 THE SECOND BOOK OF BOTANY. EXEKCISE II. Complete and Incomplete Flowers. The collection of flowers that in the previous ex- ercise were separated into symmetrical and unsym- metrical ones, may now be rearranged, separating the complete from the incomplete, according to the following definitions : COMPLETE FLOWEES consist of calyx, corolla, sta- mens, and pistil (Fig. 5). FIG. 5. Complete Flower. INCOMPLETE FLOWEES have one or more of the floral whorls absent (Figs. 6 and 7). FIG. 6. FIG. 7. Incomplete Flower. Incomplete Flower. THE FLOWER. 19 Find upon the charts examples of complete and incomplete flowers. If any of the flowers present strange appearances, let them pass ; by-and-by, after further study, you can put them where they belong. EXERCISE III. Essential Organs and Protecting Organs. The chief purpose of the flower is the production of seed ; but, to this end, some of its parts are more necessary than others: for example, the action of both stamens and pistil is needed in the formation of seeds, while they are often produced without the presence of either calyx or corolla. The stamens and pistil are therefore called the essential organs of flow- ers ; and, as the calyx and corolla cover and nourish these, they have been called the protecting organs. Point out upon the charts the protecting organs of flowers. Point out the essential organs. Do you find both sets in all the flowers represented ? Examine your collection of flowers, and point out in each specimen the essential organs and the pro- tecting organs. NOTE. The same kinds of flowers will be used over and over in observing their different features in successive exercises. But, as pupils proceed, new kinds should be constantly sought for, and, when obtained, they must be examined, with reference to all the points of the preceding exercises. New kinds of flowers are constantly opening as the season advances ; these, as they appear, should be observed with reference to all the points that have been before studied. 20 THE SECOND BOOK OF BOTANY. EXERCISE IV. Dichlamyd'eous, MonoMamyd'eous, and Achla- myd'eous Flowers. When the protecting organs, calyx and corolla, are present in a flower, it is said to be dichlamydeous (Fig. 8). FIG. 8. Dichlamydeous Flower (Gray). When there is but one whorl of protecting organs, whatever its color or texture, it is called a calyx, and the flower is monochlamydeous (Figs. 9 and 10). FIG. 9. FIG. 10. Monochlamydeous Flower. Monochlamydeous Flower. THE FLOWEK. 21 A flower destitute of protecting organs is ackla- mydeous (Fig. 11). FIG. 11. Achlamydeous Flower. Achlamydeous flowers are said to be naked. After observing the pictures, and reading the defi- nitions of this exercise, you may find upon the charts all the pictures of dichlamydeous flowers ; of mono- chlamydeous flowers ; of achlamydeous, or naked, flowers. Then look over your living specimens again, putting the dichlamydeous ones by themselves ; the mqnochlamydeous ; the achlamydeous. Pay no at- tention to the doubtful instances ; there will be fewer and fewer of these as your observations proceed. Dichlamydeous From two Greek words, signifying twice and mantle, having two coverings, calyx and corolla. Both calyx and corolla, Monochlamydeous From two Greek words, signifying sin- gle and cloalc, having a single covering; that is, a calyx without a corolla, or a corolla without a calyx. "With a single floral envelope. Achlamydeous From two Greek words, signifying without and garment. Naked, having no floral envelope. 22 THB SECOND BOOK OF BOTANY. EXERCISE V. Perfect, Imperfect, and Neutral Flowers. Pictures, illustrating this and the following exer- cise, may be found upon the charts. Living speci- mens of the kinds described will, perhaps, but rarely occur in the collections made for study. It would be well, therefore, to keep a constant lookout for them. You are likely to get them in this way before a long time, and a special search might not be successful. FIG. 12. FIG. 13. FIG. 14. A Perfect Flower. Imperfect Flowers. A PERFECT FLOWER has both the essential organs (Fig. 12). An IMPERFECT, or DICLINOUS, flower has but one of the essential organs. If it have stamens only, it is said to be staminate (Fig. 13) ; if pistil only, it is said to be pistillate (Fig. 14). NEUTRAL FLOWERS are destitute of both stamens and pistil (Fig. 15). When imperfect flowers are staminate (Fig. 13), they are said to be sterile, because they never produce seed. Sometimes they are spoken of as male flowers. THE FLOWER. 23 FIG. 15. A Neutral Flower. When imperfect flowers are pistillate (Fig. 14), they are said to be fertile, because they bear seed. They are also called female flowers. Perfect flowers, like Fig. 12, are said to be her- maphrodite, because both sexes are united in the same individual. It will be well firmly to associate the following characters with the kinds of flowers they represent : A perfect flower is indicated thus, A staminate, sterile, or male flower, thus, <$ . A pistillate, fertile, or female flower, thus, ? . Look over the charts for examples of perfect, im- perfect, and neutral flowers. Diclinous From two Greek words, signifying twofold and led, having the stamens and pistils in separate flowers. 2 24r THE SECOND BOOK OF BOTANY. EXERCISE VI. Monoecious, Dioecious, and Polygamous Plants. When both staminate and pistillate flowers grow upon the same plant (Fig. 16), it is said to be moncz- cious. FIG. 16. A Monoecious Plant When staminate and pistillate flowers grow upon separate plants (Figs. 18 and 19), such plants are said to be dioecious. Fig. 17 represents a pistillate flower from the female catkin (Fig. 18). Fig. 20 represents a staminate flower from the male catkin (Fig. 19). THE FLOWER. 25 These catkins grow upon different trees ; so the wil- low from which they were taken is dioecious. FIG. 17. FIG. 18. Pistillate Flower, from Catkin (Fig. 18). FIG. 19. Female Catkin of a Dioecious Plant. Fia. 20. Male Catkin of a Dioecious Plant. Staminate Flower, from Catkin (Fig. 19). 26 THE SECOND BOOK OF BOTANY. When staminate, pistillate, and perfect flowers are all found upon the same plant, it is polygamous. Point out upon the charts examples of monoe- cious, dioecious, and polygamous plants. Let the pupil answer the following questions con- cerning each flower of his collection : Is your flower symmetrical or unsymmetrical ? Is it complete or incomplete ? Is it dichlamydeous, monochlamydeous, or achla- mydeous ? Is it perfect or imperfect ? Did it grow upon a monoecious, dioecious, or po- lygamous plant ? Monoecious From two Greek words, signifying single and house, having the stamens and pistils in distinct flowers, but both growing upon the same plant. Dioecious From two Greek words, signifying two, or double, and house, having the stamens on one plant and the pistil on another. Polygamous From two Greek words, polus, many, and gamos, marriage, having both perfect and imperfect, or dicli- nous, flowers. EXERCISE VII. Form of the Receptacle and Insertion of Floral Organs. INSERTION. In botanical language, organs are said to be inserted at the place from which they apparently arise. For instance, in Fig. 21 it will be seen that the pistil is inserted upon the receptacle, the stamens are inserted upon the corolla, the corolla is inserted THE FLOWER. 27 upon the receptacle, and the calyx also is inserted upon the receptacle. FIG. 21. Look at the magnified flowers shown in section on chart 1, and point out the receptacle in each case. Are all these receptacles alike in form ? State, in re- gard to each flower, where the pistil is inserted ; where the stamens ; where the corolla ; and where the calyx. Which floral whorl in each flower occupies most space upon the receptacle ? Are these flowers perfect ? Are they complete ? Are they symmetrical ? Repeat these observations upon the magnified flowers shown in section in chart 2 ; in charts 3, 4, 5, 6. Make a longitudinal section of each of your liv- ing flowers, and look for the insertion of the floral organs. If you sometimes fail to discover it, do not be discouraged. It will not, of course, be as clearly visible as it is shown to be on the chart. Try again another time. Make frequent attempts, as failure is often due to lack of experience. ISO THE SECOND BOOK OF BOTANY. EXERCISE VIII. On Polyandrous Stamens. We now take up the study of the flower at just the point where it was left in " The First Book of Botany." While using that book you learned the names of the floral organs, and observed their num- ber. You also examined the calyx and corolla to learn whether or not their parts were grown to- gether. If the sepals were not grown together, the calyx was described as polysepalous, and, if they were grown together, it was said to be gamosepalous. So, also, when the petals of the corolla were distinct, the corolla was said to be polypetalous, and, when grown together, gamopetalous. We will proceed to an examination of the essen- tial organs in this respect. Gather all the flowers you can find, and observe the stamens, to see if they are grown together. Put aside all that have united stamens, whatever their de- gree of union. Now inspect the flowers with distinct stamens, and put by themselves all that have more than twelve. A flower with more than twelve distinct stamens is said to have its stamens indefinite. They are definite when there is a fixed number not above twelve. Separate those with indefinite stamens, and label them polyandrous (from poly, many, and andria, stamens), which means many distinct stamens. IsTow examine the flowers with definite stamens, and label each one with the name that, in the follow- THE FLOWER. 29 ing table, is placed opposite its number of stamens. The Greek numeral prefix denotes the number of distinct stamens : Mon-androus one stamen. Di-androus two stamens. Tri-androus three stamens. Tetr-androus four stamens. Pent-androus five stamens. Hex-androus six stamens. Poly-androus- Hept-androus seven stamens. Oct-androus eight stamens, Enne-androus nine stamens. Dec-androus ten stamens. Dodec-androus twelve sta- inens. -more than twelve. Like the word polyandrous, these terms apply only to distinct stamens ; at the same time they have the important advantage of giving the precise number. But, if a tetrandrous flower has two stamens long and two short (Fig. 22), it is said to be didynamous, Fia. 22. Fm. 23. Didynamous Stamens. Tetradynamous Stamens. and, if an hexandrous flower has four stamens long and two short (Fig. 23), it is said to be tetradynamous. These words, applied to the stamens of a flower, 30 THE SECOND BOOK OF BOTANY. give at the same time their number T the fact that they are distinct, and the proportion of long to short ones. Can you find upon the charts any flowers with tetradynamous stamens ? Have any of them didyna- mous stamens ? EXERCISE IX. The Growing together of Stamens. Having disposed of all your flowers with distinct stamens, next examine those with united stamens. First observe whether they have grown together by their filaments, or by their anthers. All those having their anthers united, whether into a tube, around the pistil, or in any other way, may be put together and labelled syngenesious (Figs. 25 and 26). FIG. 24, FIG. 25. Syngenesious Stamens, Syngenesious Stamens. THE FLOWER. 31 Fig. 24 shows this tube laid open. Those that have grown together by their filaments have to be further studied. Are all the filaments grown together in one bundle ? If so, the stamens are monadelphous (Fig. 27). Are they grown together in two bundles ? Then they are diadelphous (Fig. 28). FIG. 2T. Fia. 28. Monadelphous Stamens. Diadelphous Stamens. Are they in three or more bundles? Then we say they are polyadelphous (Figs. 29 and 30). In Fig. 29 one bundle is cut away. FIG. 29. FIG. 30. Tri- or Polyadelphous. Polyadelphous. 32 THE SECOND BOOK OF BOTANY. The number and length of the hard words in this exercise may embarrass the pupils, but a little use will make them familiar, and they will then greatly help the process of description. Collect all the plants in the neighborhood, from garden, road-side, fields, and woods, and in describing their stamens you will become well acquainted with all the necessary terms. Syngenesious (sun, Gr., together ; genesis, origin). Monadelphous (monos, Gr., one ; adelphos, brother). Diadelphous (dis, Gr., twice). Polyadelphous (polus, Gr., many). EXERCISE X. The Growing together of Carpels. You have been accustomed to counting the car- pels of flowers, and you are now to find whether or not they are grown together. All such as are not grown together at all you may label apocarpous (Fig. 31). FIG. 81. Apocarpous Pistil. THE FLOWER. 33 Those that are grown together, whether slightly at the base of the ovary or through the whole length of the pistil, you label syncarpow (Figs. 32 and 33). FIG. 32. FIG. 33. Syncarpous Pistil. Syncarpous Pistil. Find all the apocarpous ovaries pictured upon the charts. All the syncarpous ones. Find also the apocarpous ovaries in your collec- tion of flowers. The syncarpous ones. For this exercise, faded flowers, and even those that have lost their floral leaves, will serve better than such as are freshly opened. Apocarpous (apo, Gr., apart ; karpos, fruit). Syncarpous (sun, Gr., together ; Tcarpos, fruit). COHESION. In botany this word is used for the growing together of parts with their fellows, as of petals with petals, carpels with carpels. Figs. 38 and 42 illustrate this. "We now resume the use of the schedule in its appli- cation to the examination and description of flowers. The last schedule given in "The First Book" 34 THE SECOND BOOK OF BOTANY. had the word description written over its third column, and under this title could be placed all kinds of observations. But, as in this book we enter upon more careful and minute work, we shall be much aided in arranging our discoveries by adopt- ing the plan of Prof. Henslow, who places the word cohesion above this column, and devotes it to obser- vations upon the cohesion of parts in flowers. Fig. 34 represents half a buttercup. It has been sliced down through the middle, making what is called a vertical section of the flower, that you may see the structure of the stamens and pistil. This flower is used for the first schedule because of its simplicity, its parts being all quite distinct from each other. It is without cohesion, and, in describing it, you have to use terms which apply to distinct sta- mens and carpels. The learner will, of course, provide himself with a real flower, and fill out a schedule from his own ex- amination of it. The buttercup is easily found, for it grows almost everywhere, and blossoms through- out the summer. I must insist that the pupil be not content with simply looking over the description in the book. The example is given, not as a substitute for your own effort, but as a means of testing your observations ; of letting you know whether your own way of carrying out the schedule description is the correct one. Any lack of confidence you may feel in beginning a new process will disappear upon find- ing that your own observations and expressions agree with the printed ones. A schedule or two thus em- ployed, when you are beginning to use new terms, will assist you in gaining self-reliance. THE FLOWEK, FIG. 34. 35 Schedule First, describing Fig. 34, gives this ar- rangement : SCHEDULE FIRST. Organs. No. Cohesion. Cal yx ? Sepals. 5 Poly sepal ous. Corolla ? Petals. 5 Polypetalous. Stamens ? 00 Polyandrous, Pistil? Carpels. 00 Apocarpous. Questions upon the Buttercup (Fig. 34) and Schedule First. Is there cohesion in the calyx ? What word in the schedule expresses this ? Is there cohesion in the corolla ? How is this stated in the schedule ? Are the stamens definite or indefinite ? 36 THE SECOND BOOK OF BOTANY. Are they grown to each other ? What word in the schedule answers this question ? Do the carpels cohere ? How is this expressed ? Questions reviewing the Subject of Cohesion in the Parts of a Flower. What is meant by cohesion in botany ? How do you describe a calyx with no cohesion (Fig. 35)? A corolla (Fig. 37)? Stamens (Exercise VIII.)? Pistil (Fig. 41) ? When the sepals are coherent, how do you de- scribe the calyx (Fig. 36) ? The corolla (Fig. 38) ? FIG. 85. FIG. 86. Polysepalous, no Cohesion. Gamosepalous, coherent. When stamens cohere by their anthers, what word do you use in describing them (Figs. 24, 25, and 26) ? When, by their filaments in one bundle, what word is used (Fig. 27) ? In two bundles (Fig. 28) ? In three or more bundles (Figs. 29 and 30) ? How do you describe a coherent pistil (Fig. 42) ? There are a few common flowers found every- where in the country, in which there is no cohesion ; but, in most flowers, the parts of some of the floral circles will be found more or less united. Polypetalous, no Cohesion. FIG. 39. Polyandrous, Stamens not coherent. FIG. 41. Gainopetalous, coherent. FIG. 40. Triadelphous, Stamens coherent. FIG. 42. Apocarpous, no Cohesion. Syncarpous, coherent. 38 THE SECOND BOOK OF BOTANY. Figs. 43, 44, and 45 represent the flower of the Saint-John's-wort. Fig. 44 is a vertical section of the flower, and Fig. 45 one of the bundles of sta- mens. FIG. 43. FIG 44. FIG. 45. THE FLOWER. 39 Schedule Second, describing Fig. 44, is an ex- ample where cohesion of stamens and pistil is de- scribed. SCHEDULE SECOND. Organs. No. Cohesion. Calyx? Sepals. 5 Polysepalous. Corolla ? Petals. 5 Polypetalous. Stamens ? GO Tri- or Polyadelphous. Pistil ? Carpels. 3 Syncarpous. By turning to page 48 you will see that another column is there added to the schedule. After three more exercises, which introduce new observations and new terms, this addition becomes necessary. Your attention is called to it now, to give urgency to the advice that you make diligent use of the present schedule in describing all kinds and degrees of co- hesion in all sorts of flowers. If you do this, when the time comes to add this third column, your mind will be free to attend to the new features that belong to it. The terms expressing cohesion being familiar, there will be no confusion of thought, and you will enter upon the new observations with ease and pleas- ure. FIG. 46 THE FLOWEK. SCHEDULE THIRD. 41 Organs. No. Cohesion. Calyx ? Sepals. 5 Polysepalous. Corolla? Petals. 5 Polypetalous. Stamens ? 10 Monadelphous. Pistil? Carpels. 5 Syncarpous. EXERCISE XL Union of Floral Whorls with each other Calyx and Pistil. In your study of fruits (" First Book of Botany," Ex. LXVII.) did you always find the calyx at the base of the ovary ? Have you ever seen upon the apex of ripened fruit the withered calyx, or the scar left by its fall? Point out upon the charts all the cases where the calyx is below the ovary. Point to those where the calyx is above it. Is the calyx in all the pictures upon the chart either at the base or at the apex of the ovary ? For this exercise select flowers that have their parts so well developed that you can see distinctly 42 THE SECOND BOOK OF BOTANY. where each organ is inserted. Take, for example, the morning-glory, and observe whether the calyx arises below the ovary or not. If you find it is in- serted below the ovary, label it calyx below, or infe- rior (Fig. 47), and lay it aside. If the calyx is in- serted above the ovary, label it calyx above, or supe- rior (Fig. 48). Of course, if the calyx is below the FIG. 47. FIG. 48. FIG. 49. Inferior Calyx. Superior Ovary. Superior Calyx. Inferior Ovary. ovary, or inferior, the ovary will be above the calyx, or superior / and, when the calyx is superior ', the ovary will be inferior. Examine all your flowers in the same way, giving each its proper label. If some specimens have the calyx inserted neither at the bottom nor at the top THE FLOWEE. 43 of the ovary, but somewhere along its side (Fig. 50), you describe these as having the calyx half inferior, and the ovary half superior. FIG. 50. Calyx, half inferior. Ovary, half superior. NOTE. When the calyx seems to be inserted at the top of the ovary (Fig. 48), you are to regard it as really inserted on the receptacle, but as having its tube grown to the ovary, and so appearing to be inserted at its summit. The words superior and inferior came into use before the real relation of the parts was understood. The true expression is "calyx adherent to ovary," in place of calyx superior; and "calyx free from ovary," in place of calyx inferior. But the words superior and inferior are in general use, and, being short, are retained in schedule description. EXERCISE XII. The Union of Floral Whorls with each other. Corolla. You are now to determine the insertion of the corolla. Compare the arrangement of parts in each of your flowers with that shown in Fig. 51, and, when you 44: THE SECOND BOOK OF BOTANY. find the corolla inserted below the ovary, and free from the calyx, label the specimen corolla, kypogynous. FIG. 51. Corolla, hypogynous (Gray). Examine the remainder of your flowers, and, when you find one with the corolla inserted, as shown in Fig. 52, say corolla upon the calyx, or perigynous. FIG. 52. Corolla, perigynous (Gray). How is the corolla inserted in Fig. 53? Point out upon the charts where the corolla has a similar insertion. Look at the flowers not yet described, and, if you find cases where the corolla is inserted upon the ovary, describe them as epigynous, from epi, upon, and gynia, pistil (Fig. 53). THE FLOWEK. 45 FTG. 53. Corolla, epigynous. If not quite certain about these characters in your specimens, write your label with a mark of interro- gation, to show doubt. Do not be discouraged if these points of structure remain for some time trouble- some ones to discover. Try to find them out, and, if you succeed, it is well ; but, if not, it is well also. As some flowers upon the same plant are more perfectly developed than others, you should gather several of each kind, and examine them all, to find the best examples of the structure you are studying. Look at the flowers in chart 1, .and observe in each case whether the corolla arises from the re- ceptacle, and whether the calyx is free from the corolla. Find upon the other charts all the cases where the corolla is inserted under the ovary, and is free from the calyx. Observe the flowers on chart 2. Where is the corolla inserted in these figures ? Can you find upon the other charts any pictures of flowers where the corolla has a similar insertion ? 46 THE SECOND BOOK OF BOTANY. EXEEOISE XIII. Union of Floral Whorls with each other Stamens. If the stamens have the same insertion as the corolla, use the same words to describe them. For instance, in Fig. 54 the stamens are hypogynous ; in Fig. 55, perigynous ; in Fig. 56, epigynous, FIG. 54. Stamens, hypogynous. FIG. 55. FIG. 56. Stamens, perigynous. Stamens, epigynous. When you find them arising from the corolla, as seen in Fig. 57, they are said to be epipetalous. THE FLOWER. Sometimes they are consolidated with the pistil, as shown in Fig. 58 ; then they are gynandrous, or upon the pistil. FIG 57. Epipetalous Stamens. Gynandrous Pistil. Examine all the flowers you can find, and label them by the insertion of the stamens ; as, stamens un'der the ovary, or hypogynous ; stamens upon the calyx, or perigynous / stamens upon the ovary, or epigynous ; stamens upon the corolla, or epipetalous ; stamens consolidated with the pistil, or gynandrous. Adhesion in botany means the growing together of different floral whorls, while cohesion, as you have seen, means the growing together of the parts of the same whorl. The word free is used to express absence of ad- hesion, and the word distinct, absence of cohesion. In Fig. 59 there is neither cohesion nor adhesion. FIG. 59. Parts, distinct. Organs, free. THE SECOND BOOK OF BOTANY. Not only are the sepals and petals distinct from each other, not only is each stamen and each carpel distinct, but the whorl of sepals is inserted upon the receptacle, and is free from the whorls within it. The corolla is inserted upon the receptacle, and is also free. The stamens and pistil are also inserted upon the receptacle, and are likewise free. The last column of Schedule Fourth is for the record of observations on adhesion. SCHEDULE FOUBTH. Organs. No. Cohesion. Adhesion. Calyx? Sepals. 5 Polysepalous. Inferior. Corolla? Petals. 5 Polypetalous. Hypogynous. Stamens ? 00 Polyadelphous. Hypogynous. Pistil? Carpels. 3 Apocarpous. Superior. THE FLOWER. 49 Questions upon the Buttercup (Fig. 60) and its Schedule. Is the calyx free or adherent ? How is this expressed in the schedule ? Where is the corolla inserted ? How is this stated in the schedule ? Are the stamens free or adherent ? Where are they inserted ? How is this expressed in the schedule ? Is the pistil free or adherent ? How is this written in the schedule ? We have now reached the complete schedule of Prof. Henslow, which he called the flower-schedule, and which was used by his classes both at Cambridge University and at his parish school at Hitcham. Corn-- plaints have been made that it was difficult. Pupils who commence its use before they fully understand the features of plants to which it calls attention, will, no doubt, get confused when they attempt to fill up the blanks one after another, but those who have ex- amined a variety of flowers, in connection with the foregoing pages, will have no such trouble. The presence or absence of cohesion and adhe- sion in flowers is of great importance in determining the relationships of plants, and scholars cannot do better than continue the use of this schedule through- out the summer season, along with the making of an herbarium. Do not fail to fill out schedules of the following flowers, from your own observation. Never write a word of description unless it be of something your own eyes have seen, and that you could point out to any one who might contradict you. 50 THE SECOND BOOK OF BOTANY. Be careful not to copy statements from the book. I have known cases where the book was made wrong on purpose to mislead unwary and indolent scholars. FIG. 61. Fig. 61 represents a flower of cow-parsnip. That of the carrot, or any umbelliferous plant, will do as well. We give some further examples of the use of the schedule in flowers of very unlike structure. SCHEDULE FIFTH. Organs. No. Cohesion. Adhesion. Calyx? Sepals. 5 Gamosepalous. Superior. Corolla? Petals. 5 Polypetalous. Epigynous. Stamens ? 5 2 Pentandrous. Epigynous. Pistil? Carpels. Syncarpous. Inferior. THE FLOWER. 51 Fig. 62 shows a vertical section of the flower of daffodil. It is common enough in gardens ; but, if there are pupils who can get neither this flower, nor the jonquil, nor the snow-drop, they can certainly find a lily of some kind, wild or cultivated, and ob- serve the features in which it is unlike this picture. SCHEDULE SIXTH. Organs. No. Cohesion. Adhesion. Perianth ? Leaves. 6 Gamophyllous. Superior. Stamens ? 6 Hexandrous. Perigynous. Pistil ? Carpels. 3 Syncarpous. Inferior. 52 THE SECOND BOOK OF BOTANY. Fig. 63 is a blossom of wild geranium. Figs. 64 and 65 are the stamens and pistil of the same. The flower of the garden geranium will serve in its place, if it can be more easily obtained. In Fig. 70 this pistil is again shown. FIG. 63. FIG. 64. FIG. 65. SCHEDULE SEVENTH. Organs. No. Cohesion. Adhesion. Calyx ? Sepals. 5 Polysepalous. Inferior. Corolla ? Petals. . 5 Polypetalous. ( Hypogynous. Stamens ? 10 Decandrous. Hypogynous. Pistil ? Carpels. 5 Syncarpous. Superior. THE FLOWER. 53 EXEKOISE XIV. The Receptacle. The peculiarities of plants pointed out in this and the following exercise are not very common. But pupils who are using the flower-schedule, and collecting all the plants they can find, will be sure to meet with examples of them sooner or later. These exercises should, therefore, be carefully read, and borne in mind, so that, when the features they de- scribe are met with, they may be recognized. Before passing to the more minute observation of the floral organs, the receptacle requires further study. You have seen it forming a central convexity, like that of Fig. 66, and gradually expanding into a structure like Figs. 67 and 68. Sometimes the re- FIG. 66. Convex Receptacle. FIG. 6T. FIG. 68. Receptacle, enlarged, and shown in Section. The same, fully developed. 54: THE SECOND BOOK OF BOTANY. ceptacle is prolonged between the carpels, and co- heres with their styles, which separate from it at maturity, as seen in Figs. 69 and 70 (Gray). PIG. 69. FIG. 70. It sometimes appears as a cup-shaped depression (Fig. 71), in which the pistil is almost concealed, and again as shown in Fig. 72. FIG. 71. FIG. 72. Cup-shaped Eeceptacle. Elevated Fleshy Eeceptacle. THE FLO WEB. 55 Whenever the receptacle becomes elongated, so that one circle of floral organs is separated from another by a stalk-like internode, the circle thus raised is said to be stipitate, and the stalk supporting it is called a stipe. In Figs. 73 and 74-, the stamens, pistil, and corolla, are stipitate, and the stalk which bears them is the stipe. FIG. 73. Authophoiv. 6, Gonophore ; o, Gynopbore, Gynobase, or Carpophore (Gray). 56 THE SECOND BOOK OF BOTANY. When the stipe supports corolla, stamens, and pistil, it is called an aitfhophore (Fig. 73). When it supports only stamens and pistil, it is known as the gonopJiore (Fig. 75, 5) ; the gynophore^ gynobase, or carpophore, when it bears the pistil alone (Fig. 75, c). Thalamus The receptacle of the flower, or the part of the peduncle into which the floral organs are inserted. Torus Another name for thalamus. Receptacle (recipio, I receive). Thalamus A bed. Torus A couch. EXERCISE XV. Appendages of the Receptacle. Examine the receptacle in the magnified flowers upon charts 1, 2, 3, and 4. Carefully observe the space between the calyx and ovary in the figures opposite. You see a sort of fleshy cushion at the base of the ovary in one case, at the base of the style in another. The raised rim around the pistil is called a disk. It takes on very different shapes in different plants. In Figs. 76 and 77 it is merely a raised cushion ; in Fig. 78 it is seen partly enclosing the ovary. In Figs. 79 and 80 the disk is seen surrounding the ovary, while in Figs. 81 and 82 it is shown above the ovary, and at the base of the style. FIG. 76. THE FLOWEK. FIG. 77. Hypogynous Disk. Hypogynous Disk. FIG. 79. Fro. 78. Hypogynous Disk. Perigynous Disk. Epigynous Disk. Epigynous Disk. 58 THE SECOND BOOK OF BOTANY. The little glands upon the receptacle are known as nectaries. They contain sweet fluids, and are found among the stamens (Figs. 83 and 84), or at the base of the pistil, forming a part of the disk (Figs. 85, 86, and 87). FIG. 83. FIG. 84. FIG. 85. FIG. 86. FIG. 87. CHAPTER II. COMPARING AND CLASSIFYING PLANTS. EXEKCISE XVI. Plant Characters and Affinities. You are now to take a step forward in the study of plants. Having acquired considerable knowledge of their parts by direct observation, you will begin to compare them to note their resemblances and differences as wholes, and, by these resemblances, to 60 THE SECOND BOOK OF BOTANY. arrange, or group, them in a systematic way. This is classification. You have been doing something of the kind ever since you commenced observing plants. For in- stance, those with parallel-veined leaves have been classed by themselves, and those with flowers in um- bels have been associated together, and kept distinct from such as blossom in heads or in panicles; but your groupings have thus far been made upon single features of plants, as was inevitable in the beginning of study. You are now prepared to gi-asp at once in thought more parts of structure, and make your com- parisons more full and complete. If, for example, you have put into one group all square-stemmed plants, simply because they have square stems, it is time to consider whether these plants are alike in other features. " Oh, yes," some of you will say, " they have opposite leaves." Well, look at their inflorescence ; do they all agree in that ? Is it always axillary ? Are the flowers similar in all the square-stemmed plants you know ? When you have answered these questions, you will understand what I mean by studying plants as wholes. And now, how shall you set to work ? First, provide yourself with the following plants : The buttercup (which is found almost everywhere), the wild-columbine, and the poppy. If the columbine is not to be found, get monk's-hood, or larkspur, or anemone, and proceed with them in the way pointed out for the columbine. If the poppy cannot be found, you might substitute blood-root, or celandine. Having got the plants, proceed according to the plan laid down, and do not accept the statements or con- COMPARING AND CLASSIFYING PLANTS. 61 elusions of the book, unless, on comparing them with your own plants, you see that they are true. There are two botanical expressions, of which, at the outset, you should learn the meaning. One of these is the characters of plants, and the other the affinities of plants. And, first, what is meant by plant-characters f If you will describe a buttercup, I think we can easily find just what is meant. You say, " CALYX, sepals, 5, polysepalous, inferior ; COROLLA, petals, 5, polypetalous, hypogynous; STA- MENS, many, hypogynous ; PISTIL, carpels, many, apo- carpous, superior." Yes; but what about the rest of the plant? You answer: "It has simple, exstipu- late, alternate, divided leaves; petiole spreading at base ; stem, erect ; flowers, in a loose cluster ; juice, watery, acrid. Now, this is the description of a particular but- tercup, and yet it applies to all buttercups. Are all buttercups, therefore, exactly alike? By no means. They differ in size, shape, thriftiness, number of blossoms, etc. ; but, in our botanical description, we do not record these individual peculiarities. "Well, the points of form and structure in which all buttercups agree, that is, their permanent feat- ures, are called by botanists the characters of the buttercup. All such unchanging features of plants are plant-characters. A plant is simply an assem- blage of characters, and the description of a plant is but a list of its characters. Now, it is by comparing groups of characters that we reach the idea of affinities. If, as we have seen, each plant bears a fixed group of characters, the re- 62 THE SECOND BOOK OF BOTANY. semblance of one plant to another is only the resem- blance of one group of characters to another. Let us make such a comparison between the buttercup and columbine. Do not rely upon the descriptions in the book, but make similar tables yourself. BUTTERCUP. Flower. Calyx. Sepals, 5, polysepa- lous, inferior. Corolla. Petals, 5, polypeta- lous, hypogynous, obcordate, yellow. Stamens. o>, hypogynous. Pistil. Carpels, o>, apocar- pous, superior. COLUMBINE. Flower. Calyx. Sepals, 5, polysepa- lous, inferior, colored like the petals. Corolla. Petals, 5, polypeta - lous, hypogynous, spurred, red. Stamens. oo, hypogynous. Pistil. Carpels, 5, apocar- pous, superior. Comparing the above lists, you see agreements and differences. The calyx and corolla of one plant agree with those of the other in number of parts and in the position of parts. They differ only in color and outline. The stamens of one are like those of the other in being numerous and hypogynous. The pis- tils agree in structure, but differ in the number of carpels. If you compare the leaves, stems, inflores- cence, etc., you also get a list of their resemblances and differences. This is comparing plants by the groups of characters they present. These resemblances of character among plants are called their affinities. The degree of affinity between plants depends upon two circumstances: first, upon tho kind of COMPARING AND CLASSIFYING PLANTS. 63 characters in which they agree; and, second, upon the number of characters in which they agree. The characters of plants differ in importance. Such kinds of character as color, size, and odor, being usually more variable than such kinds as position, size, and number, they are said to be less important than these. The characters of the leaf, for the same reason, are not usually as important as the characters of the flower. In the beginning of study, you may safely assume that those plants are most alike, have the strongest affinities, that re- semble each other most in the characters recorded in the cohesion and adhesion columns of the schedule. To make this plainer, compare the poppy and buttercup, as, before^ you compared the columbine and buttercup. BUTTERCUP. Calyx. Sepals, 5, lous, inferior. Corolla. Petals, 5, polypeta- lous, hypogynous. Stamens. Polyandrous, hypo- gynous. Pistil. Carpels, many, apo- carpous, superior. Leaves. Net- veined, divided. Juice. Watery. POPPY. Calyx. Sepals, 2, polysepa- lous, inferior. Corolla. Petals, 4, polypeta- lous, hypogynous. Stamens. Polyandrous, hypo- gynous. Pistil. Carpels, many, syn- carpous, superior. Leaves. N"et-veined, divided. Juice. Milky. To find which has the strongest affinity for the buttercup, the columbine, or the poppy, all that is necessary, at present, is, to ascertain which of them is nearest like the buttercup in respect to cohesion and adhesion of the parts of the flower. 64 THE SECOND BOOK OF BOTANY. On examination, you see that the columbine, like the buttercup, is perfectly destitute of cohesion, while in the poppy you have a coherent, or syncarpous, pistil. This settles the question. The affinity of the columbine for the buttercup is greater than that of the poppy. If you compare their leaves, you will find those of the poppy more like buttercup-leaves than are those of the columbine, but differences in leaf-struct- ure do not usually signify as much in classification as differences in the pistil. Compare, in the same way, the hollyhock and the Saint- John's- wort with mallows, and decide which has the strongest affinity for the mallows. Compare the flower of the locust and of the gera- nium with that of the pea or bean. I mention these plants, not because they are use- ful above all others for your purpose, but to start you in the work. It really matters little what plants you take, if you only carefully compare the group of characters of each one with that of the others, and endeavor to discover the affinities they present. EXERCISE XVII. Sow to begin Classification. If you have made the comparisons pointed out in Ex. XVL, you are prepared for an explanation of the plan by which you are to begin to classify plants. As COMPARING AND CLASSIFYING PLANTS. 65 we made use of the buttercup and columbine to learn the meaning of affinity in botany, a little further statement about them will, perhaps, be helpful be- fore we pass to the regular work of the exercise. The buttercup is said to be more thrifty, more at home in low, damp places. It is like frogs in this respect ; and, because of this, it is named after them. Its botanical name is Ranunculus, from Eana, a frog. The Kanunculus has certain characters with which you are familiar. Now, when you find other plants which are very much like it, that is, which present nearly the same group of characters, particularly those of cohe- sion and adhesion, you class them with it, you say they belong with the buttercup ; or, in more botani- cal language, they belong to the Kanunculacese. In some regions this plant, from the form of its leaf, is called the Crowfoot, and plants closely resembling it are said, therefore, to belong to the Crowfoot family. Now, the resemblance of the columbine to the butter- cup entitles it to belong to the Ranunculacese. The monk's-hood and larkspur also belong to the same family, and this will give you some idea of the degree of similarity that should exist between members of one family. Our object in the present exercise is, to fix upon a method by which to begin the work of classifying plants, by comparing the groups of characters they present, and putting together those that are most alike. Get a pocket note-book. Write in it, boldly and plainly, the flower-schedules of the following plants : Buttercup, shepherd' s-purse, mustard or radish, catch- 66 THE SECOND BOOK OF BOTANY. fly, mallows, Saint- John's- wort, clover, pea or bean, wild-rose, strawberry, geranium, violet, morning- glory. Now, why have we put these particular schedules into the note-book ? Compare them with each other. Do you not see that the statements in the cohesion and adhesion columns are widely unlike? This is why we have chosen them. They are so many dif- ferent patterns of the make-up of flowers, and you have simply to compare each flower you describe with one and another of these patterns, to see which is the best fit. If none of them fit at all, then set up your new acquaintance as another pattern, and see if you can find any of its relations in the course of the sum- mer. So, do not confine yourself to comparisons be- tween your specimens and the patterns in your note- book. Compare them freely with each other, and you will soon have many little collections of plants bearing very strong resemblances to each other. Your thought will be something like this : While you are observing and describing a plant, you will ask yourself, " Have I ever before described one like it in the matters of cohesion and adhesion I " If you can think of none, you will try to recall those near- est like it. By pursuing this plan, you will be sur- prised to find how quickly many of the plants of a region, that were never before thought of as at all alike, fall into company on the ground of these deeper resemblances which your studies have led you to dis- cover. The reason why you are set systematically to clas- sifying plants now, and have not been asked to do it before, is, that among the characters of plants that COMPARING AND CLASSIFYING PLANTS. 67 belong to roots, leaves, stems, etc., there are none that are so uniform throughout large numbers of dif- ferent plants as these features of cohesion and adhe- sion in flowers. Since you began to observe plants, you have not been taught to notice any points of structure that would serve so well for uniting plants into groups, the members of which are truly and somewhat nearly related to each other. But the grounds on which you are to begin to classify plants, although important, and, in many cases, quite sufficient, are not the only ones on which classification is based. Though they may sometimes be found too narrow, yet you must begin somewhere, and, to make your beginning as free as possible from complexities, you start with the features named in the flower-schedule. In working with this, much of your experience will be clear and satisfactory, but you may meet with difficulties. By-and-by, however, the sub- ject will be resumed, and, if you have sometimes been confused and puzzled in classifying by the flower- schedule alone, new ideas will be all the more wel- come. Students who have the botanical charts will find them very helpful in the work of classification. Upon these charts there are pictured in the colors of Nature some forty pattern-plants, magnified, and shown in section, so that their structure is easily seen. These plants have been selected because the differences they present are just those broad contrasts that separate groups of plants in Nature. At this stage of your study, while your thoughts are confined to the feat- ures of the flower-schedule^ the first, second, third, and fifth charts present pattern-plants of all varieties 68 . THE SECOND BOOK OF BOTANY. in these respects. Their great value to the pupil, in classification, at the beginning of study, lies in the distinctness of the idea he gets from them as to how his pattern-plant is constructed. The work of classification being now entered upon, it will be resumed, from time to time, with further explanations as we proceed, particularly when we come to study such groups of plants as the grains and grasses, the cone-bearing plants, the Composite, fa- miliarly known as compound flowers, the Umbel- liferae, etc. These striking natural orders will intro- duce us to new principles in judging of affinities, and pupils who are specially fond of this part of the study, and are apt in tracing resemblances, will do well to look over the chapters upon these plants without waiting to reach them in the course of regular study. NOTE. There is often, among both teachers and pupils, an aversion to skipping about. The idea of thoroughness with them seems to imply moving steadily on from page to page of a book, without ever deviating from its order. But in such a science as botany it is not necessary to proceed in this way. The subject cannot be marked off sharply into parts that must be learned in a certain order. Of course, plant characters must be known before they can be used in classification ; but, when a few are known, they may be at once put to service. A pupil cannot do better than to acquaint himself with the group of cruciferous plants as soon as the special characters that be- long to this group are familiar. Any group of plants may be classified as soon as the characters upon which it is founded are fairly known. To get a knowledge of classification requires much time, and its study should, therefore, be commenced at the earliest possible moment. There is another reason for skipping about, which will be at once appreciated. It is this: Plants have their time to flower, and their flowers must be studied at that time. For CHAPTEE III. THE STAMENS. EXEKCISE XVIII. Parts of Stamens, COMMENCE this exercise by examining the parts of a well-formed stamen. Select, for this purpose, a flower with stamens having large anthers. If they have not yet shed their pollen, all the better. Com- pare this anther with Fig. 88, and look for the parts pointed out in the picture. FIG. 88. \ . Connective. J Anther Lobe, or Cell. Anther Lobe. example: the Conifer blossom in spring, and spring is the time to study them. Stamens may be found throughout the entire season, and so may be studied at any time. It would be folly, therefore, to let the period pass in which the Conifers might be studied, because you u hadn't come to them " in the book, and pursue the study of stamens because they are next in order. Again, the characters of orchids are illustrated by a plant which has its season, and the time to study orchids is when this plant makes its appearance. 70 THE SECOND BOOK OF BOTANY. Do you see in your specimen a groove down the middle of the anther on one of its sides ? Is there any thing like a ridge on the other side of the an- ther, opposite the groove ? Can you divide the anther at this place without coming upon the pollen ? What name is given to this part of the anther in Fig. 88 ? What are the two halves it connects called ? Look at your living anther for the line along each lobe, called the line of dehiscence in the figure. What name is given in Fig. 89 to the sides of the anther-cells ? (Of course, each lobe has two valves ; but, as they are opposite, only one can be shown in a picture.) ANTHER-LOBE. The cell which holds the pollen (Fig. 88). CONNECTIVE. A continuation of the filament which unites the two lobes of the anther. It is often inconspicuous or absent, but is sometimes easi- ly seen (Fig. 88). VALVES. The sides of an anther-lobe. LINE, OR POINT, OF DEHISCENCE. The opening through which the pollen escapes. It may help the learner in forming a distinct idea of these different parts of the anther, to know that the stamen is looked upon by botanists as a sort of leaf, the filament answering to the petiole, and the anther to the blade. The connective corresponds to the mid -rib of a leaf, and the line of dehiscence to its margin, each lobe being half of a leaf-blade, and THE STAMENS. 71 the valves of an anther corresponding to the upper and under sides of a leaf. Examine the anthers of as many different flowers as possible, and try to find the cells, connective, line of dehiscence, valves. Do not be disappointed or discouraged if, in many cases, you fail to distinguish some of the parts. Look at the magnified stamens on the charts, and find, if you can, the parts of the anther named in this exercise. EXEEOISE XIX. Number and Shape of Anther- Lobes. NUMBER OF ANTHEB-LOBES. FIG. 90. FHJ. 91. FIG. 92. One-celled Anther. Two-celled Anther. 4 Four-celled Anther. 72 THE SECOND BOOK OF BOTANY. FIG. 93. SHAPE OF ANTHEE-LOBE8. FIG. 94. FIG. 95. Arrow-shaped Anther. Oblong Anthers. FIG. 96. Emarginate Anthers. Sinuous Anthers. EMARGINATE. When the summit, or base, of the anther-cell extends upward or downward, a little be- yond the connective (Fig. 96). Label each flower of your collection with the number and shape of the anther-cells of its stamens. THE STAMENS. Y3 Find, if you can, upon the charts instances of one- celled anthers, of two-celled anthers, of four-celled anthers. Mention the form of each anther-lobe pict- ured upon the charts. EXERCISE XX. Dehiscence of the Anther. FIG. 98. FIG. 99. FIG. 101. FIG. 102. FIG. 103. Vertical, or Longitudinal. Transverse. Porous. Valvular. Valvular. VERTICAL, OR LONGITUDINAL DEHISCENCE. When the anther opens by a slit along its length to emit the pollen (Fig. 98). TRANSVERSE. When the line of dehiscence is across the anther (Fig. 99). POROUS. When the anthers emit the pollen through little pores (Fig. 101). VALVULAR. When a portion of the anther is lifted up to emit the pollen (Figs. 102 and 103). 74: THE SECOND BOOK OF BOTANY. In describing the stamens of flowers you will now observe the kind of dehiscence the anther exhibits. Name the various modes of dehiscence of anther- cells shown upon the charts. EXERCISE XXI. Introrse and Extrorse Anthers. When the valves of the anther are of equal size, the dehiscence will occur laterally (Fig. 106) ; but, if one valve be wider than the other, it will throw the line of dehiscence nearer to the connective on one side than on the other. The narrowed valves are usually on the projecting side of the anther-cell, and this is called the face of the anther (Fig. 104). FIG. 104. FIG. 105. Face. Back. The other side, where the connective is usually visible, if seen at all, and where the filament is at- tached in most cases, is called the l)ack of the anther (Fig. 105). NOTE. The projecting side of the anther-cell is called its face, and the opposite side is called its ~back, whether the valves are unequal or not. THE STAMENS. 75 FIG. 106. FACING THE PISTIL. FIG. 107. Lateral Dehiscence. Introrse Anthers. Anthers are INTKOKSE when the line of dehiscence, or face, of the anther, is toward the pistil. FACING THE COROLLA. FIG. 108. FIG. 109. Extrorse Anthers. Extrorse Anthers. Anthers are EXTKOKSE when the line of dehis- cence, or face of the anther, is turned toward the corolla (Figs. 108 and 109). 76 THE SECOND BOOK OF BOTANY. Look over the charts for examples of extrorse and introrse anthers. In future observe the stamens of living^ flowers with reference to this feature. EXERCISE XXII. Attachment of Filament to Anther. FIG. 111. FIG. 112. Innate. Innate. INNATE. Anthers are innate, or fosifi&ed, when the filament runs directly into the base of the con- nective (Figs. Ill, 112, and 116). ADNATE. Anthers are adnate, or dorsifixed, when the filament runs up the back of the anther, joining the connective in such a way that the anther is hung in front of it (Figs. 113 and 114). VERSATILE. If the filament is attached by a slen- der apex to the middle of the anther, the ends of which swing freely up and down, the attachment is said to be versatile (Fig. 115). FIG. 113. THE STAMENS. Fra. 114. FIG. 115. Adnate. FIG. 116. Basifixed. Dorsifixed. ' v- Apsffixed. The modes of attachment, pictured and named above, shade into each other, so that, in practice, it is often difficult to determine them. The versatile passes into the adnate, and the adnate into the in- nate, and a nice exercise of judgment is sometimes needed in describing this feature of flowers. Find these several modes of attachment on the charts. Determine and describe the mode of attach- ment in each of your living specimens. 78 THE SECOND BOOK OF BOTANY. EXERCISE XXIII. Forms of Filaments. FIG. 122; FIG. 123. FIG. 124. Filiform. Sub-ulate. Capillary. FILIFORM filaments are thread-like, as the name de- notes, but strong enough to support the anther (Fig. 122). SUB-TIL ATE filaments taper like an awl (Fig. 123). CAPILLARY filaments are hair-like, and too slender to support the anther (Fig. 124). DILATED filaments are flattened out like Fig. 126. PETALOID filaments resemble petals in form, and bear the anther at the summit, as seen in Figs. 127 and 128. BI-DENTATE, or Bi-cuspiD, filaments are toothed at the summit or at the base, as seen in Figs. 129 and 130. Find examples of the several kinds of filaments upon the charts. Describe the different forms of filaments in your collection of plants. FIG. 125. THE STAMENS. FIG. 126. FIG. 127. Fro. 128. 79 FIG. 129. Dilated. Petaloid. Bi-dentate. Bi-dentate. EXERCISE XXIV. Structure and Forms of Pollen. The pollen-grain is generally composed of two membranes, or coats, filled with a thick liquid sub- stance containing minute grains, which is its essential portion. The outer coat is frequently marked with bands, lines, and grooves, or covered with bristling points (Fig. 131). The inner coat is very thin, and swells when wetted. If you moisten pollen-grains ? you may often see, with a microscope, the expanded inner coat protruding through openings in the outer coat (Fig. 131). EXTTNE. The outer coat of a pollen-grain, usually with openings, or very thin in certain places (Figs. 131, 132, and 133). INTINE. The inner coat of a pollen -grain, very 80 THE SECOND BOOK OF BOTANY. thin, tough, and elastic, often seen protruding through holes in the extine (Figs. 132 and 133). FOVILLA. The rich protoplasmic liquid contained within the intine (Fig. 133). FIG. 181. FIG. 132. FIG. 182*. FIG. 183. FIG. 134. Intine. Fovilla. Extine. Polinia. POLINIA. Pollen-grains cohering in masses. In Fig. 134 they are in pairs, and are furnished with stalk-like processes ; but in some plants they are sin- gle, and without a stalk. FIG. 185. FIG. 136. THE STAMENS. 81 Pollen-grains display a great variety of shapes. Besides the round and oblong (Figs. 135 and 136), you will find them angular, lobed, and joined to- gether in various ways (compound pollen) by threes, fours, and even larger numbers (Fig. 132). Look at the various forms of pollen pictured upon the charts. Examine the pollen of flowers with your magni- fying-glass, and note the shape of the grains, and the kind of surface they present. Observe the moistened pollen of various plants under the microscope. EXERCISE XXV. Forms of Connective. FIG. 187. FIG. 138. FIG. 139, FIG, 140. FIG. 141. Appendicular. Connective, widened. 82 THE SECOND BOOK OF BOTANY. FIG. 142. Anther. Connective. Abortive Anther '^_^ Filament Dimidiate. APPENDKKJLAR. When the connective, extending above or below the anther, takes the form of a feather, or a lengthened point, or a fleshy mass, or spur-like appendages, or stipules (Figs. 137, 138, and 140). When one lobe of an anther is abortive, or sup- pressed, the anther is said to be dimidiate. Fig. 142 represents a dimidiate anther and a connective de- veloped into arms, so that the lobes are entirely dis- connected. Observe the abortive anther-lobe of Fig. 142. The entire stamen, as well as each of its parts, is liable to suppression, abortion, or imperfect develop- ment. The symmetry of flowers is often 'destroyed in this way. In some plants the non-development of organs that exist in the rudimentary state is a constant character, and should be regarded in de- scribing them. Observe the figures on the chart which illustrate these forms of connective. Look over the flowers of your collections, and in future describe the form of connective when you can distinguish it. THE STAMENS. EXERCISE XXYI. General Features of Stamens* 83 FIG. 143. FIG. 144. EXSEETED. Stamens are said to be exserted when they extend beyond the corolla (Fig. 143). INCLUDED. When the stamens are not as long as the corolla, they are said to be included (Fig. 144). The entire whorl of stamens is called the androe- cium. When the filament is wanting, the anther is de- scribed as sessile. When the anther is wanting, the stamen is said to be sterile. Converging stamens are said to be connivant. 84 THE SECOND BOOK OF BOTANY. In observing and describing stamens, the follow- ing schedule will be found useful by calling attention to the several characters pointed out in the present chapter : Stamen Schedule. Parts ? Number of anther-lobes ? Shape of anther-lobes ? Attachment of filament and anther? Facing ? Form of filament ? Form of pollen ? Form of connective ? General features ? Adnate (Lat., adnascor, I grow to) Grown fast to, or formed in union with, another body. Appendicular (Lat., appendo, I hang up) Having an ap- pendage. Basifixed (Lat., basis, the base) Attached by the base. Dimidiate (Lat., dimidiatus, halved) Appearing as if one half were wanting. Dorsifixed (Lat., dorsum, the back) Fixed upon the back. Extrorse (Lat., extra, externally; orsus, originating) Turned outward. FomlloB (Lat., foveo, I nourish) Minute particles in the fluid contained in pollen. Innate (Lat., innatus, inbred) Borne directly on the apex of a thing. Intine (Lat., internus, internal) The inner lining of pollen- grains. Introrse (Lat., introrsus, inwardly) Turned toward the axis. Subulate (Lat., subula, an awl) Awl-shaped. Versatile (Lat., versatilis, that turns easily) Swinging to and fro. * CHAPTEE IY. THE PISTIL. FIG. 144. EXERCISE XXVII. Kinds of Stigma FIG. 145. FIG. 146. FIG. 147. Scrolled. Globose. Lobed. 86 THE SECOND BOOK OF BOTANY. EXERCISE XXVIII. Form and Position of Styles. FIG. 155. FIG. 156. FIG. 157. FIG. 158. Sigmoid. Lateral. Basal. Terminal The shapes of styles may be named by the same words as the shapes of filaments. Observe, in faded flowers and young fruit, whether the styles are persistent or deciduous. EXERCISE XXIX. Kinds of Pistil. It will be convenient to apply the following names to certain distinctions among pistils with which pupils are now familiar : FIG. 159. A Compound Pistil. A COMPOUND PISTIL (Fig. 159) consists of several united carpels is syncarpous. FIG. 160. THE PISTIL. FIG. 161. 87 FIG. 162. A Simple Pistil. Multiple Pistil. Multiple Pistil. A SIMPLE PISTIL (Fig. 160) consists of only a sin- gle carpel, and is, of course, apocarpous. A MULTIPLE PISTIL (Figs. 161 and 162) consists of several distinct carpels is also apocarpous. EXERCISE XXX. The Structure of Ovaries. "Whether a pistil is simple, multiple, or compound, each carpel may be looked upon as a single leaf. The simple pistil of the pea, for instance, may be regarded as the blade of a leaf folded at the midrib, so that its inner portion answers to the upper face of a leaf, and its outer portion to the under face. Its dorsal suture will correspond to the midrib, and its ventral suture to the margin of the leaf. To make this plainer, take any strong oblong leaf (Fig. 163), and fashion it into a carpel, like the pea- pod, taking the upper part of the leaf for the inner 88 THE SECOND BOOK OF BOTANY. part of the carpel. Fold in the margins slightly to represent the placentae (Fig. 164). (See " First Book," Ex. LXVIII.) If the fold will not stay in place, take a stitch or two along it with a needle and thread. Now double it at the midrib (Fig. 165), and compare it with a pea-pod. Find the valves; the dorsal and ventral portions ; the stigma ; the base. FIG. 164. FIG. 165. Gather some old, faded pea-blossoms, in which the ovary is somewhat enlarged, and observe that the ventral suture is turned inward ; that is, it lies along the central line, or axis, of the flower. It is along this axis, then, that the double placentae are formed. Observe the position of the dorsal suture, or back of the pod. It is important to bear in mind that, in the case of the simple pistil, the ovules are attached cen- trally along the axis of the flower. THE PISTIL. 89 Roughly to imitate a multiple pistil, you have only to bind together, by their petioles, several leaf- blades that have been converted into carpels, as above. Observe the placentation of any multiple pistil, and you will invariably find that the placenta of each carpel is central in the same way that, in the artificial one, you have made the margins of your carpellary leaves turn inward, and the midribs out- ward. After thus preparing simple and multiple pistils from foliage leaves, let us try to construct a com- pound pistil from leaf-blades. If we can do this, it will give us a clear understanding of the structure of syncarpous ovaries. Form, from foliage leaves, an artificial ovary, of three coherent carpels. A three-celled compound pistil consists of three carpellary leaves grown to- gether. It is as if, by pressing together the carpels of your multiple pistil, they should unite by their sides. To make an artificial compound pistil, then, you have only to select three large symmetrical foli- age leaves, and pin or stitch them together in such a way that their margins will meet in the centre, and their under surfaces will form its outer wall. If you cannot get leaves of firm texture that will hold a pin or stitch without tearing, try lining them with some thin cloth or paper. Fold each of the leaves at the midrib, with the upper surface inward, as seen in Fig. 166. Fasten the left half of one leaf-blade' to the right half of another, so that the united portions will form a double wall between the cells, and the six edges will meet together at the centre, as repre- sented in Fig. 167. 90 THE SECOND BOOK OF BOTANY. Your aim being simply to understand how, and from what, each part of a compound pistil is formed, you need not care for the clumsiness or shapelessness of your manufactured ovary. Point out its cells. Its dissepiments. Explain why they are double. Point out the dorsal and ven- tral suture of each carpel of your syncarpous struct- ure. Where should you look for ovules in this pistil ? Fio. 166. FIG. 167. FIG. 168. Prepare a compound ovary by joining three leaves at their margins, as seen in Fig. 168. In what part of an ovary so formed are the leaf-margins? In what part of the ovary would you look for the ovules ? The theory of the pistil is important, because it gives clear ideas of the varied and complex charac- ters of ovaries ; and these characters are of the first importance in classification. THE PISTIL. 91 EXERCISE XXXI. Placentation. After studying the structure of ovaries as ex- plained in Ex. XXX., the following definitions will be easily understood : PLACENTATION. The arrangement of placentae is called placentation. To determine the mode of placentation of a plant, slice its ovary across, and compare its appearance with the following figures. The formation and arrange- ment of placentae are so various, that we have given an unusual number of drawings to illustrate the defi- nitions. AXILLARY PLACENTATION. When the ovules are found along the central line, or axis of the pistil, the placentation is called axillary r , or axile (Figs. 169, 170, ITl, 172, and 173). Fio. 169. FIG. 170. FIG. 171. FIG. 172. FIG. 173. 92 THE SECOND BOOK OF BOTANY. FKEE-CENTKAL PLACENTATION. "When the dissepi- ments, or double partitions, between the cells are ab- sent, leaving the placentae and ovules at the centre, and all the cells opening into one chamber, the pla- centation is said to be free-central (Figs. 174, 175, 176, and 177). FIG. 174. FIG. 175. FIG. 176. FIG. 177. PARIETAL PLACENTATION is seen when the placen- tae are attached to the walls, or projections from the walls, of the ovary, as is illustrated in the following figures (178-185) : THE PISTIL. 93 FIG. 178. FIG. 179. FIG. 180. FIG. 181. FIG. 182. FIG. 183. FIG. 184. FIG. 185. FALSE DISSEPIMENTS. It will be well to know that, in many ovaries, there are partitions not formed in the way described in Ex. XXX. The following are instances of what are known as false dissepiments : FIG. 186. FIG. 187. Observe in Fig. 186 a partition going inward from the dorsal suture, and nearly reaching the centre of the flower. Fig. 1ST shows a similar false partition not quite so much extended. 94: THE SECOND BOOK OF BOTANY. FIG. 188. FIG. 189. FIG. 190. V. Fig. 188 is a section across the middle of an ovary, and Fig. 189 is a section across the upper part of the same ovary. The partitions that appear in one and are not seen in the other, must be false they cannot be formed by the sides of adjacent carpels. In Fig. 190 the placentae are parietal, but a mem- brane is formed, reaching across the ovary, and form- ing a false dissepiment. These false dissepiments, you see, are developed, in some cases, from the dorsal suture ; in others, from the placentae. It may sometimes be difficult to decide between true and false dissepiments ; but, as your knowledge of plants increases, the different members of the same group will often be found to afford transitional char- acters that make evident what otherwise would be uncertain. EXERCISE XXXH. Modes of Dehiscence. To understand the modes of dehiscence, pictured in this exercise, you have only to prepare a three- celled compound ovary, as directed in Ex. XXX., THE PISTIL. 95 observing the place of the dorsal and ventral sutures, the relations of the valves, and that the partitions are double. REGULAR OR VALVULAR DEHISCENCE. Dehiscence is said to be valvular when the ovary separates into the regular pieces called valves. FIG. 191. FIG. 192. FIG. 193. The dehiscence is SEPTICIDAL when the ovary splits through the partitions, each dissepiment separating into its two layers, one belonging to each carpel (Figs. 191, 192, and 193). FIG. 194. FIG. 195. The dehiscence is LOCULICIDAL when the splitting opens into the cells by the dorsal suture, as seen in Fig. 195, which represents the ovary of a violet, where 5 THE SECOND BOOK OF BOTANY. the carpels flatten out as soon as they are released from each other. FIG. 196. FIG. 197. FIG. 198. Septifragal. The dehiscence is SEPTIFEAGAL where the valves fall away, leaving the dissepiments behind attached to the axis (Figs. 196 and 197). IRREGULAR DEHISCENCE. Seeds are sometimes dis- charged through chinks, or pores (porous dehiscence) (Fig. 198), or the ovary may burst in some part irregu-. larly. Now compare the capsules in your collection with the figures and definitions given in this exercise, and determine, if you can, the mode of dehiscence of each of them. How would you produce loculicidal dehiscence in the compound ovary you have made with leaves, as directed in the opening of this exercise ? How septicidal ? How septifragal ? THE PISTIL. 97 EXERCISE XXXIII. Direction of Ovules and Seeds. Ovules have an horizontal direction when they are neither turned upward nor downward, as in Figs. 199 and 200. They are ascending when rising ob- liquely upward, as in Fig. 201. FIG. 199. FIG. 200. FIG. 201. Ovules are said to be erect when rising upright from the base of the cell (Fig. 202). They are sus- pended when hanging perpendicularly from the sum- mit of the cell (Fig. 203). They are pendulous when hanging from near the top (Fig. 204). FIG. 202. FIG. 203. FIG. 204. 98 THE SECOND BOOK OF BOTANY. EXERCISE XXXIV. Parts of the Ovule. FIG. 205. Primine. Apex of Ovule. Secundine. Base of Ovule - BASE or OVULE. The point of union of the fti- niculus and ovule ; not of the funiculus and placenta (Fig. 205). APEX. The part of the ovule opposite the base (Fig. 205). PRIMINE. The outer sac of an ovule (Fig. 205). SECUNDINE. The inner sac of an ovule (Fig. 205). These parts are again shown in Figs. 206 and 207, along with others that appear when we make a section of the ovule. FIG. 206. Apex of Ovule. Micropyle. Base of Nucleus. Bhaphe. -- \ Chalaza. THE PISTIL. 99 FIG. 207. Chalaza. Base of Nucleus. Primine ... _ --Rhaphe ,-. ,. r- \ \ :! **.-:* f-vr.vT J.W.M.^/AA^ Secundme Nucleus.-- --N MICROPYLE. The opening in the coats of an ovule, or seed (Figs. 206 and 207). NUCLEUS. The substance contained within the sacs, in which the embryo is formed (Figs. 206 and 207). RHAPHE. The connection between the base of the nucleus and the base of the ovule. In Fig. 206 the rhaphe is short, and concealed within the ovule, but in Fig. 207, where the position of the nucleus is so changed as to bring its base round to the apex of the ovule, the rhaphe is visible, and extends along one side, still connecting the base of the nucleus with the base of the ovule. CHALAZA. The place where the coats and nucleus grow together. HILUM. The scar left by the separation of a seed from its placenta. It is not supposed that pupils will find all these parts of the ovule in plants. Some of them are usu- ally discernible, and they may all be understood in their proper relations by studying the diagrams. 100 THE SECOND BOOK OF BOTANY. EXERCISE XXXV. Kinds of Ovule. FIG. 208. FIG. 209. Micropyle. Straight, or Orthotropous. Curved, or Campy lotropous. The STRAIGHT, or ORTHOTROPOUS OVULE, has the base of the nucleus and the base of the ovule in the same position, while the micropyle is at the apex (Fig. 208). In the CURVED, or CAMPYLOTROPOUS OVULE, the micropyle, or apex, is bent over close to the base (Fig. 209). FIG. 210. FIG. 211. Rhaphe.-- f m jf J|_ Micropyle . Chalaza \1K__._ Micropyle . / ^ Jf ~" - Chalaza. Ehaphe.'' Inverted, or Anatropous. Half-inverted, or Amphitropous. In the INVERTED, or ANATROPOUS OVULE, the fu- niculus lengthens, and bends round, growing fast to the coat, until the base of the nucleus is at the apex of the ovule (Fig. 210). In the HALF-INVERTED, or AMPHITROPOUS OVULE, the funiculus only lengthens till the ovule turns a quarter of the way over, as in Fig. 211. THE PISTIL, " w ' 101 (The pupil is referred to page 118,' the close of the chapter on fruit, for a list of questions a sort of pistil-schedule to be used as a guide in describing this organ.) Amphitropal (Gr., amphi, about ; trepo, I turn). Anatropal (Gr., ana, over ; trepo, I turn) An ovule turned over, so as to bring the micropyle to the hilum. Axile (Lat., axis, an axle-tree) Belonging to the centre, or axis. Campylotropal (Gr., campulus, curved; trepo, I turn) An ovule, or seed, bent so as to bring the apex near to the hilum. CJialaza (Gr., a spot on the skin) The place in a seed where the nucleus joins the integuments. Dehiscence (Lat., dehisco, I gape) Splitting into parts. Dissepiment (Lat., dissepio, I separate) Partitions in a fruit. Hilum (Lat., the black scar of a bean) The scar left by the separation of a seed from its placenta. Loculicidal (Lat., loculus, a cell) A mode of dehiscence through the back of a carpel. Micropyle (Gr., mikros, small; pule, gate) The scar in the skin of a seed, which was the foramen in the ovule. Nucleus (Lat., a kernel) The centre of an ovule, where the embryo is formed. Ortliotropal (Gr., ortlios, straight; trepo, I turn) An erect ovule, with the foramen or micropyle opposite the hilum. Parietal (Lat., paries, a wall) Growing to the walls of an ovary. Placentation (Lat., placenta, a cheese-cake) The way the placentae are developed. Primine (Lat., primus, first). RJiapJie (Gr., rhapJie, a seam) The thread connecting the placenta and nucleus. Seeundine (Lat., secundus, second). Septicidal (Lat., septum, a hedge; ccedo, I cut) A mode of dehiscence dividing the dissepiment. Septifragal (Lat., septum, a hedge; frango, I break) A mode of dehiscence where the valves fall away from the dis- sepiment. CHAPTEE Y. THE FRUIT AND SEED. EXEKCISE XXXYT. The Composition of Fruit. FRUIT. The ripened ovary, witli its contents, is the fruit of plants. Whatever adheres to the ovary also becomes part of the fruit. In studying fruit, observe with care what parts, besides the pistil, have been concerned in its forma- tion. In describing flowers, you note whether the pistil is inferior or superior ; is there any reason to suppose that inferior fruit would be most likely to have other parts of the flower besides the pistil united with it ? Did you observe the flowers of the cherry, plum, or peach trees, and those of apple and pear trees when they were in blossom ? and if so, will you compare your recollection of them with the appear- ances presented by their fruit ? If you have forgot- ten their structure, perhaps you have kept a descrip- tion of them, and can refresh your memory. Observe the ripe fruit of the cherry. Look at the top of the peduncle for scars left by the parts of the fallen flower. Look for a dot at the top of the fruit, showing the place of the style. Has any thing but the pistil entered into the formation of this fruit ? Observe the plum, peach, grape, currant, etc., and see if they are like the cherry in these respects. THE FKTJIT AND SEED. 103 Now examine an apple or pear. What do you find at the top of the fruit, opposite the peduncle ? It must be the remains of the calyx-limb, the tube of which you saw united to the pistil when you studied it in flowering-time. Of what, then, does the fruit consist? Divide an apple or pear, as shown in Fig. 212. Find the parts shown in this diagram. The re- M mains of the flower are seen at C. The calyx-tube, grown fleshy and succulent, is marked T. The outer border of the ovary is seen at E. From what part of the flower is the eatable portion of a pear or apple developed? To repeat our former question, would the fruit of a superior pistil be more likely than that of an inferior pistil to consist of the ovary alone ? I have illustrated the composition of fruit with apples and cherries because they are so common ; but these observations may, and should be, repeated upon every variety of fruit that can be found. Trace the formation of each of the fruits pictured upon the charts, and point out those that consist of the pistil alone, and those which do not. In the lat- ter case, name the parts that are consolidated with the pistil in the fruit. 104: THE SECOND BOOK OF BOTANY. When fruit is formed from the pistil alone, the wall of the ovary is called a pericarp (from peri, around). Gather specimens of every kind of fruit that grows within reach. In late summer or early au- tumn, the fruit of garden, field, and forest, if care- fully collected, will give you a large and various as- sortment. For example : you may have at the same time cucumbers, melons, beans, peas, grapes, apples, pears, elder and pokeweed berries, chestnuts, wal- nuts, pumpkins, etc., and the less conspicuous seed- vessels of mullein, Saint- John's- wort, lettuce, radish, cabbage, etc., etc. Earlier in the season the list will be different, and it will vary somewhat with the lo- cality, but, wherever collected, and whatever its com- ponents, be sure to gather every kind that can be had. Look over your collection, and separate the supe- rior from the inferior fruits. Observe the structure of those formed from inferior pistils, and point out the pericarp in those formed from superior pistils. Preserve, for further study, the specimens you have gathered. EXERCISE XXXVII. Farts of the Pericarp. EPICARP. When the walls of a pericarp are formed of two or more layers of different texture, as in the peach, plum, or cherry, the outer one (the skin, in the case of these fruits) is called the epicarp. ENDOCARP. The stony case around the seed of the THE FRUIT AND SEED. 105 peach, plum, or cherry, is called the endocarp. But the endocarp of fruits is not always stony. "Whatever its texture, the inner layer of a pericarp is named the endocarp. MESOCAKP. Sometimes, between the outer and inner parts of a pericarp, there is found a third layer of different aspect, like the pulp of a peach. This third layer is called the mesocarp. The distinction between the epicarp and mesocarp is often very slight, and then both together are called the epicarp. FIG. 213. In Fig. 213 e is the endocarp, s the mesocarp, and g the epicarp. In Fig. 212 E is the epicarp, N the endocarp, and S the seeds. At N is shown a slight development of the mesocarp. Point out these parts in an apple and a peach. Point out the parts of the pericarp in the different fruits pictured upon the charts. Classify your collection of fruits by the structure of the pericarp. Put by themselves all those that have but one layer in the pericarp. Put those with two layers an epicarp and endocarp by themselves, leaving those with three layers epicarp, mesocarp, and endocarp. Describe the layers that make up the fruit ; that is, say whether, in each case, the layer is pulpy, woody, stony, membranous, leathery, etc. 106 THE SECOND BOOK OF BOTANY. Preserve your collection for further study, and add to it all you can get. EXERCISE XXXVIII. The Classification of Fruit. Look over your collection and separate the dehis- cent from the indehiscent fruits. The indehiscent group may now be further separated into juicy fruits and dry fruits. Compare your specimens of juicy fruit, one by one, with the following pictures and definitions of fruits. The first picture is that of a berry ; so you may first find the berries of your col- lection. To determine whether a particular fruit is a berry or not, cut it across, and see if it agrees in structure with Fig. 214, and the requirements of the definition. Never mind whether your conclusion ac- cords with common speech or not ; whether a straw- berry turns out to be a berry or not ; but follow the definition wherever it leads. Indehiscent Juicy Fruits. BEEET. A thin-skinned, indehiscent, fleshy fruit, having the seeds embedded in the pulpy mass (Figs. 214 and 215). FIG. 214. FIG. 215. THE FRUIT AND SEED. 107 HESPERIDIUM. A kind of berry with a leathery rind (Fig. 216). (Example, lemon and orange.) FIG. 216. PEPO. The pepo is an indehiscent, fleshy fruit, with seeds borne on parietal placentae, and with the epicarp more or less thickened and hardened. (Ex- ample, squash.) POME is the term applied to a fleshy, indehiscent, several-celled fruit, with a leathery, or cartilaginous, endocarp, enclosed by the calyx-tube. Figs. 217 and 218 are transverse and vertical sections of a pome. (Example ; apple and pear.) FIG. 217. FIG. 218. DRUPE (example, peach or cherry) is a pulpy, in- dehiscent, one-celled, one or two seeded fruit, with a succulent or fibrous epicarp, and hard, stony, dis- tinct endocarp (Figs. 219 and 220). 108 THE SECOND BOOK OF BOTANY. FIG. 219. FIG. 220. If you have blackberries, raspberries, and the like, among your fruits, compare one of the little cells that make up this kind of fruit with this definition of a drupe. Indehiscent Dry Fruits. Select from among your dry indehiscent fruits all those that resemble Figs. 221, 222, 223, and 224, and that are usually miscalled seeds. You will find upon many of them such appendages as hairs, teeth, plumes, bristles, etc. FIG. 221. FIG. Vertical Section of Carpel of Buttercup. THE FRUIT AND SEED. 109 FIG. 223. FIG. 224. They are achenia. An ACHENIUM is a dry, inde- hiscent, one-seeded fruit, with a separable pericarp, tipped with the remains of the style (Figs. 222-224). UTRICLE. By this term is understood a kind of achenium, with a thin, bladdery pericarp which is sometimes dehiscent. FIG. 225. FIG. 226. CARYOPSIS. A dry, indehiscent, one-celled, one- seeded fruit, with the pericarp adherent to the seed, as seen in wheat, barley, oats, maize, etc. (Fig. 226). CREMOCARP. Pendant achenia. (See Ex. LII). CYPSELA. Still another variety of achenium, 110 THE SECOND BOOK OF BOTANY. with an adherent calyx-tube, as in composite (Fig. 222). FIG. 227. FIG. 228. Nwr. A hard, one-celled, one-seeded, indehiscent fruit, produced from a several-celled ovary, in which the cells have been obliterated, and all but one of the ovules have disappeared during growth. It is often enclosed in an involucre, called a cupule (Fig. 227), or it has bracts at the base. SAMARA, or KEY-FRUIT (example, the elm). A dry, indehiscent fruit, growing single or in pairs, with a winged apex, or margin (Fig. 228). Dehiscent Fruits. Any dry, dehiscent fruit, whether simple or com- pound, may properly be called a pod. FOLLICLE. A pod of a single carpel, with no ap- parent dorsal suture, and dehiscing by the ventral suture. You will seldom find an ovary consisting of but one follicle ; but it is a common kind of carpel in multiple pistils. Observe the ripe ovary of colum- THE FKDTT AND SEED. Ill bine or pseonia. Each carpel is a follicle, and you may find them slightly coherent at the base, as if forming a transition between the apocarpous and syncarpous pistil. LEGUME. A pod of a single carpel, with dorsal and ventral sutures and dehiscing by both or either, as the pea and bean pod. It assumes many different forms. One of these, the LOMENT, is a sort of legume with transverse joints between the seeds, and falling to pieces at these joints (Fig. 229). Another variety, the SILIQTJE, is a two-valved, slender pod, with a false dissepiment, from which the valves separate in dehiscence. It has two parie- tal placentae (Fig. 230). FIG. 229. FIG. 230. FIG. 231. FIG. 232. SILICLE. A short, broad silique (Fig. 231). PYXIS. A pod which dehisces by the falling off of a sort of lid (Fig. 232). 112 THE SECOND BOOK OF BOTANY. CAPSULE. The pod of a compound pistil ; the dry, dehiscent fruit of syncarpous pistils (Figs. 233 and 234). The pieces into which a capsule falls at dehis- cence are called valves, the same as in one-carpelled fruit. Fia. 233. FIG. 234. Those fruits that consist of achenia on a dry re- ceptacle, as the sunflower, or on an enlarged, pulpy receptacle, as the strawberry, or those which consist of small drupes on a dry, spongy receptacle, crowded almost into one mass, as the blackberry, are aggregate fruits. They are sometimes called etcerio. Accessory, or anthocarpous fruits, are such as con- sist of other parts of the flower only apparently joined with the ovary. MULTIPLE, COLLECTIVE, or CONFLUENT Furors, are formed by the union of many separate flowers into one mass (Figs. 235 and 236). The sorosis is a kind of multiple fruit, to which THE FRUIT AND SEED. 113 the pineapple (Fig. 235) belongs. The fig is a mul- tiple fruit of the kind known as syconus, while strobilus is the name given to the multiple fruit of trees of the pine family. FIG. 235. Fia. 236. EXEKOISE XXXIX. The Seed. Its Form and Surface. The forms of seeds vary very much. They may be globular, ovoid, reniform, oblong, cylindrical, topshaped, angular, etc. Some seeds are small and fine, like sawdust ; others are flattened and bordered, as seen in Fig. 237. FIG. 237. 114 THE SECOND BOOK OF BOTANY. The surfaces of seeds may be smooth, striated, ribbed, furrowed, netted, and tubercular, as shown in the following figures : FIG. 238. D Smooth. FIG. 241. FIG. 289. FIG. 240. Netted. Tubercular. Furrowed. Seeds are said to be definite when few and con- stant in number ; indefinite when numerous and va- riable. Seeds are solitary when single in the ovary, or in a cell of the ovary. The albumen of seeds is the mass of tissue in which the embryo is embedded. It is said to be mealy when it may be readily broken down into a starchy powder ; oily, when loaded with oil ; mucilaginous, when tough, swelling up readily in water ; and horny, when hard, and more or less elastic. ALBUMINOUS SEEDS are those which have albumen. EXALBUMINOUS SEEDS are those in which the body consists of the embryo alone. THE FRUIT AND SEED. 115 The relations of embryo to albumen in various seeds are here shown. Your own observation, how- ever, must have already supplied you with much in- formation upon this subject. FIG. 244. FIG. 245. FIG. 246. FIG. 247. FIG. 248. EXERCISE XL. Position of the Embryo in Seeds. As the dissection of seeds is such an easy opera- tion, you must be familiar with the different aspects of the embryo in many different seeds. You have seen it large and small, straight and curved, outside the albumen and embedded within it; sometimes with flat cotyledons, and sometimes with cotyledons folded or coiled in various ways and degrees. We are now to observe its relation to the parts of the In studying ovules, you found the hilum and the micropyle, and you may find the same parts in the seeds that were once ovules. The hilum of seeds is 116 THE SECOND BOOK OF BOTANY. usually obvious enough, and the micropyle may be easily found. You have only to soak the seed till its coats are distended with water, and, on squeezing, the micropyle, or orifice in the coats, is made appar- ent by the escape of water at that point. The place of the micropyle is important, because the radicle of the embryo always points toward it, and, in sprout- ing, issues through it, and the relation of the micro- pyle to the hilum determines the attitude of the em- bryo. Seeds are straight, half inverted, inverted, and curved, the same as ovules, and the same terms are used to express these facts in regard to them. In a straight or orthotropous seed (Fig. 249), the micro- pyle being at the apex, you find an inverted embryo, like Fig. 250. In this case the embryo is said to be antitropal, or reversed. FIG. 249. FIG. 250. Micropyle. ; Hilum. If the micropyle be turned to one side, as in Fig. 251, an amphitropous seed, the embryo, will be ob- FIG. 251. FIG. 252. FIG. 253. THE FRUIT AOT) SEED. 117 lique, as seen in Fig. 253. In this case the embryo is said to be heterotropal. Fig. 252 represents the seed which is shown in section in Fig. 253. If the seed be inverted, or antitropous (Fig. 254), the embryo will be erect, as shown in Fig. 255. Here the embryo is said to be orthotropaL FIG. 254. FIG. 255. Micropyle. In Fig. 256, which represents a seed curved upon itself so as to bring the orifice next the hilum, or point of attachment (campylotropous seed), you may find the embryo presenting the appearance shown in Fig. 257. FIG. 256. FIG. 257. Hilum. :^f v Micropyle. When the embryo is in the centre of the albumen (Fig. 255), it is said to be axial; and when not in the centre, it is said to be excentric. Among the various modes of folding to which the embryo is subject, there are two which have been specially noticed and named, because they occur so uniformly in certain groups of plants. They are cotyledons accumbent ; that is, with the radicle folded against their edges ; and cotyledons incumbent, having the radicle folded against the back of one of them. 118 THE SECOND BOOK OF BOTANY. The following questions, forming a pistil-schedule, may now be used as a guide for pupils in describing this important organ of plants : Form and position of stigma ? Form and position of style ? Kind of pistil ? Placentation ? Dehiscence ? Direction of ovules ? Kinds of ovules ? Fruit? Seed? Embryo ? Achenium (Gr., #, not ; chaino, I open). Capsule (Lat., capsula, a little chest). Caryopsis (Gr., Icare, a head ; opsis, appearance). Cremocarp (Gr., Icremao, I hang; karpos, fruit). Cypsela (Lat., a martin, or swallow). Drupe (Lat., drupcz, unripe olives). Epicarp (Gr., epi, upon; Tcarpos, fruit). Endocarp (Gr., endon, within). Etcerio (Gr., etarios, a companion). Follicle (Lai., folliculus, a little bag). Legume (Lat., legumen, pulse). Loment (Lat., bean, meal). Mesocarp (Gr., mesos, middle ; karpos, fruit). Pome (Lat., pomum, an apple). PT/zis (Lat., a little box). Silique (Lat., siliqua, a husk, or pod). Sorosis (Gr., sThe growth of plants takes place, either by the expansion of existing cells, or by the formation of new ones, and principally by the latter method. "The contents of the cells of the growing part divide into two, and between the halved contents there forms a thin layer, which di- vides each cell into two distinct cells. The new cells, then, increase in size until they become as large as their parent-cell, when they each divide again, and the process is repeated. The process is modified according as the cells are to lengthen or to remain short." The rate at which cells are formed may be gath- ered from such a fact as the growth of a huge puff- ball, sometimes nearly a foot across, in a single day. In this sudden growth it has been estimated that 300,000,000 or 400,000,000 cells are produced in an hour. Century -plants, growing in conservatories, after many years produce a flowering stem six inches in diameter. The entire vigor of the plant is devoted to the growth of this stalk, which ascends at the rate of a foot in twenty-four hours. Estimating the cells at -gfa of an inch in diameter, there are formed more than 20,000,000,000 a day. EXERCISE LXIV. Vessels or Ducts, and Fibres. EXPERIMENT. Take some of the boiled pulp of any soft vegetable substance, as rhubarb, that can be picked to pieces with needles. Put a bit of this 202 THE SECOND BOOK OF BOTANY. stringy pulp ID a little water, and separate from it some of its smallest threads. Put these on the glass with a drop of water, and arrange the thin cover as FIG. 364. FIG. 365. before. "When magnified, you will see among the cells long, tube-like bodies, having their walls marked with rings and spirals, such as are shown in Fig. 364. Examine slices taken both across and lengthwise from the young, succulent, fast- growing shoots of any plant ; from the ribs, petiole, or veins of leaves ; from parts of the flower, of roots, or of underground stems. By carefully looking at these sec- tions, you will again see embedded among the cells tubes of varying length, and with different aspects. These tubes are called ducts. EXPERIMENT. Take a small bit of soft wood, half the size of a pea, and boil it in a few drops of nitric acid for several sec- onds. Rinse it carefully with water three or four times, to cleanse it from acid, and pick it to pieces, as you did the fibre of rhubarb. Examine a minute portion of this wood under the microscope. You will THE INTEKNAL STRUCTURES OF PLANTS. 203 see long, tapering threads overlapping each other, something like Fig. 365, and called fibres. Vessels, or Ducts, as Prof. Gray prefers to call them, are continuous tubes of considerable length, of which the walls are never smooth, but marked with dots, bars, rings, spirals, etc. They are sometimes cylindrical, and some- times tapering in form, and contract a lit- tle from place to place along their length, as seen in Fig. 366, where circles are formed by the constriction. The meaning of these constrictions may be gathered from the following EXPERIMENT. Select from vegetable pulp some of the stringy portion contain- ing vessels, and pour upon it boiling water, sharpened by a few drops of nitric acid. The vessels will break up into fragments at the places of these circles. At these points, also, you will find partitions across the vessel, more or less perforated and broken, or mem- branous folds, that may come from the breaking of these partitions. Hence, it appears that a vessel is formed from a row of cells, placed end to end ; the partitions, which at first separated these cells, being more or less completely removed. Vessels, or ducts, like cells, are named from the markings on their walls. There are dotted, barred, spiral, and annular vessels (Figs. 367-370). Fig. 371 represents scalariform ducts, so named from the lad- der-like markings on their walls. Fibres, also, are produced from cells; they are cells altered in certain ways. All vegetable tissue is at first cellular, and it is by the elongation of cells 204 THE SECOND BOOK OF BOTANY. into fibres, as well as by their union and modification in various ways, that all the elements of vegetable structures are produced. FIG. 867. FIG. 863. FIG. 869. FIG. 870. FIG. 871. Fibres vary in length, and their walls thicken with age by the deposit upon their interior of new layers filling up the cavity. As long as any cavi- ty remains it will be round, while, by pressure, the external wall becomes flattened and prismatic (Fig. 372). In fibrous tissue (Fig. 373) you see the taper- ing, overlapping extremities, making the texture close and solid. The largest fibres of wood are found in trees of the pine family cone-bearing trees where they are as much as -g-J-g- or ^-i-g- of an inch in diameter. Their size varies in different families of THE INTERNAL STRUCTURES OP PLANTS. 205 plants as much as does that of cells. The fibres of basswood are about yVo" f an i ncn diameter. FIG. 372. FIG. 373. But the compactness of fibrous tissue depends more upon the thickness of the walls of its fibres than upon their fineness. Hence the density of the old heart- wood of trees, where the cavities of the fibres are en- tirely filled by deposited matter. Woody fibres rarely exceed -% of an inch in length, while the fibres of some kinds of wood are only y^-g- of an inch long. Tissues formed of elongated cells, particularly of such cells as have tapering extremities, are called prosenchyma. The cells of prosenchyma vary much in length and proportions. Woody tissue is made up chiefly of prosenchyma, yet some wood consist 3 largely of parenchyma, in which the cells have be- come solid by the deposits upon their interior. At first the elongated cells of wood have their ends nearly square, but, as they lengthen and crowd each other, they become wedge-shaped. The blending of cells, fibres, and vessels, in the tissues of a plant, is shown in Fig. 374, which repre- 206 THE SECOND BOOK OF BOTANY. sents a greatly-magnified section of the Indian reed. At the left you see cellular tissue, or parenchyma ; then annular and spiral vessels, dotted ducts, and fibres. FIG. 374. Again, Figs. 375 and 376 are drawn from sections of the wood of the plane-tree. In Fig. 376 you see the open mouths of the ducts, which are shown ver- tically in Fig. 375. EXPERIMENT. To observe the coiled threads upon the walls of vessels, tear gently the young shoots of the rose-bush or elder, or carefully pull asunder the petiole, or one of the veins of a strawberry-leaf, just breaking the cuticle, and only stretching the internal parts. Or, even, if the parts are quite separated, you may see with the naked eye, at the point of fracture, THE INTERNAL STRUCTURES OF PLANTS. 207 the broken, mutilated coils of spiral vessels. The uncoiling, spiral thread is thus easily seen, but the wall of the vessel is difficult to find. FIG. 875. FIG. 376. FIG. 377. These membranous threads of spiral vessels con- tinue, without interruption, from one end of the ves- sel to the other. In most cases they are simple, but sometimes they are found double (Fig. 377), triple, etc. Even twenty juxtaposed threads have been seen forming a ribbon, and unrolling all together. Spiral threads, that at first were simple, sometimes split into several very fine threads. The spiral thread is neither tubular nor channelled ; it may be round, flat, or square. The markings of annular vessels, like Fig. 377, and vessels that have at the same time both annular and spiral threads (Fig. 369), reticulated, scalariform, and dotted vessels, are produced in the same way as are simi- lar markings upon cells, as explained on page 199. " When you break a stalk or leaf of milkweed, let- 208 THE SECOND BOOK OF BOTANY. FIG. 378. tuce, dandelion, etc., there exudes a milky sap, called latex. There is a peculiar system of vessels containing this milky juice, known as laticiferous vessels. They form an irregular net-work, as seen in Fig. 378. It is thought that these so-called laticiferous vessels are not true vessels made up of cells placed end to end, but only intercellular spaces with walls formed by a deposit from the fluid that fills them. They never have markings up- on their walls like the vessels we have been studying. When young, laticiferous vessels are extremely small, averaging less than -^Vfr of an inch in diame- ter, and can only be seen under high magnifying powers. Old vessels, when swollen from accumulations of their milky sap, are more ap- parent. As you see by Fig. 378, they are cylindrical, and the branches are as large as the veins, forming a sort of net-work. But this kind of vegetable struct- ure is not well understood. EXERCISE LXV. The Contents of Cells. The contents of cells vary with their stage of growth. When very young they usually contain only the nucleus and protoplasm, but, as they approach THE INTERNAL STRUCTURES OF PLANTS. 209 maturity, various substances are found within them, of different kinds and amounts in different species of plants. Look at a section of potato under the micro- scope, and observe the minute grains within the cells. Compare your specimen with Fig. 379. Fig. 380 represents some of the cells more highly magnified. FIG. 879. FIG. 380. EXPERIMENT. Place upon the freshly-cut surface of potato, apple, or almost any fresh vegetable, a drop of tincture of iodine. These starch-granules will be colored violet, indigo-blue, or deep-blackish blue, depending up- on the strength of the solution used. If there are albuminous granules in the cell, they will be colored brown or yellow by the iodine. By this means the con- tents of the cell are made more distinct, and the cell-wall is ren- dered more obvious. Starch-grains are either irregular, spheroidal, or egg-shaped bodies (Fig. 380), having their surfaces marked with concentric circles around points. These 210 THE SECOND BOOK OF BOTANY. circles indicate so many layers superposed around a little kernel indicated by the central point. In looking, with the microscope, at sections of leaves, you will see gelatinous flocks of green matter swimming in the colorless liquid of the cells, or de- posited on the cell-walls and grains of starch. This substance, to which vegetation owes its green color, is called chlorophyll. The yellow coloring-matter of plants is like chlorophyll in every respect, except its color, but the red, violet, and blue coloring-matters are always liquid. The colorless sap of plants, which fills the cells and vessels, holds in solution all the materials of cell- growth, and of the substances contained in cells. Su- gar, dextrine, and gum, dissolved in water, are found in the cells, the intercellular spaces, and lacunes, but, being held in solution, they cannot be detected by the microscope. The intercellular spaces, also, fre- quently contain air. The fixed oils found in seeds and fruits, and other parts of the plant, form isolated glo- bules, that, by pressure, flow together into large glo- bules. Essential oils, turpentine, and caoutchouc, are usually accumulated in intercellular cavities, or given oif at the surface when the plant is wounded. Yarious mineral matters are also taken up by the roots from the soil, dissolved in water, and deposited in the structure of the plant. They occur sometimes in the crystalline form in cells. Indeed, it is said that almost every herbaceous plant contains them in more or less abundance. Fig. 381 represents cells of rhubarb, from one of which needle-shaped crystals, called raphides, are being ejected. Cells of this kind in the stalks of rhubarb, when moistened with water, THE INTERNAL STRUCTURES OF PLANTS. 211 become distended so as to burst, and force out the con- tents, as here shown. Cells with similar contents are also found in the leaves of four-o'clock, Indian tur- nip, and calla. These cell-crystals are sometimes ag- glomerated into masses of angular crystals (Fig. 382). FIG. 882. That these crystal are formed in the cells is proved by the fact that the shape of the cell determines the form of the crystal. SUea, the substance known every- where as sand, exists, dissolved, in the sap of plants, and is deposited in the stalk of grains in such quanti- ties as to give them the requisite stiffness. CHAPTEK XYI. THE STRUCTURE OF STEMS, Now that you have seen the various kinds of cells, fibres, and ducts, and the tissues they form, the next step is to discover how they are put together in the construction of roots, stems, leaves, flowers, fruit, and seeds. To do this we begin with the embryo, and trace its development from germination to maturity. As the growing radicle, the chief part of the embryo, from which roots, stem, and leaves proceed, is itself stem, we will study the stem first. EXERCISE LXVI. Structure of Dicotyledonous Stems. First Year's Growth. The monocotyledonous embryo starts with a sin- gle lobe, turned a little to one side of the plumule, while the dicotyledonous embryo develops two oppo- site lobes, spreading away laterally from the plumule. This is but the beginning of a series of differences in structure, which these two classes of plants will pre- sent as growth proceeds ; hence, they must be studied separately. We begin with dicotyledons. You are familiar with the succession of external ap- pearances presented by the growing plantlet. In Fig. 383 (Gray) you see the part which was the embryo ending above, in the plumule, and below, in the root. THE STRUCTURE OF STEMS. 213 The plant is again shown in Fig. 384 (Gray), after the production of two internodes and two pairs of leaves. The stem still ends with a bud, and the root FIG. 388. FIG. 384 has undergone further development. Now, what in- ternal changes have accompanied these external ones ? Cells have elongated into fibres, or united into ducts, and, if we examine a thin section of a young stem, we may observe the way in which these ele- ments are arranged. Whether we take our section from a sprouting maple, which would represent the woody plants of temperate regions, or from a sprout- 214 THE SECOND BOOK OF BOTANY. ing melon, as an example of herbaceous ones, the appearances at first presented would be nearly the same. Fig. .385 represents a section of the stem of a melon. You see it is a mass of cellular tissue, with several wedge-shaped bodies, forming a circle midway be- tween the centre and the cir- cumference. Make such a sec- tion of a young dicotyledonous stem, and observe it with your microscope. Look for the cen- tral cellular portion called the pithy marked M in the figure. Observe that the outer portion is cellular, and that central and outer cells are con- nected by cellular strips (KM), which separate patches of denser matter. If you make a vertical section through some of these denser patches, you will find them largely composed of fibres and ducts. Passing from the centre outward, the parts you have noticed are the following : PITH, or MEDULLA. The central cellular portion (M, Fig. 385). MEDULLARY RAYS. The radiating cellular bands that connect the pith with the circumference (K M). WOODY, or FEBRO- VASCULAR BUNDLES. The wedge- shaped bundles of fibres and ducts. CORTICAL LAYER. The green cellular envelop of the other parts. Carefully peel off some of the skin from the same stem, and examine it under the magnify ing-glass. You see it consists of flattened, irregular cells, closely THE STRUCTURE OF STEMS. 215 united into a firm membrane. This is the epidermis, and, excepting the stigma, it covers all the parts of a plant exposed to the air. By suitable means the epi- dermis may be separated into two parts, the outer of which is not cellular, and exists sometimes in the lower plants when the cellular portion is wanting. A great French chemist, named Fremy, has shown that it is like caoutchouc, and is named the cuticle. EXERCISE LXVII. Structure of a Woody Bundle. As the woody bundles of dicotyledons are essen- tially alike, and as they make up the main substance of the stem, we shall get the best idea of stem-struct- ure by observing their composition. Fig. 386 repre- FIG. 386. sents a highly-magnified section of one of these bun- dles, with its surrounding cellular tissue. Observe the region marked C. It is made up of greenish cells of extreme delicacy, and it is from these cells that all the other parts are produced. New cells are constantly forming here, and old ones are changing 10 216 THE SECOND BOOK OF BOTANY. into fibres and vessels of various kinds. This is the cambium layer. Outside of this layer, and by a transformation of its outer cells, the bark is formed ; within the circle made by the cambium and by trans- formations of its inner cells wood is produced. The narrow end of this woody bundle, which lies next the pith, and is marked T in Fig. 386, con- sists of spiral ducts and thick-walled fibres ; between these and the cambium layer is the true woody re- gion, comprising about half the bundle. It is made up of woody fibre, with annular, barred, and dotted ducts interspersed. The line E.M points to the medullary ray, F to the woody fibres and small annular fibres, VP to large ducts of various kinds. Beyond the cambium we come upon L, the inner bark, or liber, and then follows the outer bark. The lower half of Fig. 387 represents a vertical FIG. 387. section of the woody bundle shown in the upper half of the picture. Observe in the horizontal section the cambium layer, marked c ; the true wood is seen THE STRUCTURE OF STEMS. 217 passing from A at the right ; and the bark, with its different layers, at the left. Trace these different portions in the vertical section. EXEKCISE LXYIII. The First Year's Growth. (CONTINUED.) The number and compactness of the woody bun- dles in a young stem will depend upon the time of the observation ; if it is made early in the season, there will be few (Fig. 388), and their number will increase with the growth and multiplication of the FIG. 888. FIG. 389. FIG. 390. leaves. This increase is shown in Fig. 389, where six new bundles are seen inserted between the first six shown in Fig. 388 ; while in Fig. 390, which rep- resents a woody stem at the close of the year, they are shown filling all the space, except the narrow strips of the medullary rays. Bearing in mind the composition of a woody bundle, as shown in the last exercise, look again at the section of a dicotyledonous stem during the first 218 THE SECOND BOOK OF BOTANY. year's growth (Fig. 391). Passing outward from the medulla, or pith, marked M, we come first upon the spiral ducts of the woody bundles, marked T. They form a sort of sheath around the pith, only broken by the medul- lary rays (KM), and, as they en- close it, they are called the me- dullary sheath. This portion of the woody bundle is contin- uous with the petiole and frame- work of leaves. EXPERIMENT. Divide the bark and most of the wood of a young shoot by a circular cut, and gently pull it asunder ; you may detect this sheath by the stretched and broken spiral threads of its fibres. Outside of the medullary sheath, observe the lig- neous fibres, or zone, of true wood. Encircling this is the cambium layer. Up to this point, excepting its somewhat less density, the herbaceous and the woody stems are alike. It is in the portion external to the cambium that we come upon differences. The cambium and bark, it will be seen, are important in plants that are to live over to another year, while they are of little account to the herb, which dies in autumn. In herbaceous stems, as the melon, there- fore, the bark consists of simple parenchyma, like that of pith, except that it is of a green color ; but in woody stems, as the maple, it takes on a much higher development, and presents important differ- ences of structure. All the while that wood is forming, bark is also being made. That portion of it next the cambium is wrought into woody tissue, THE STRUCTURE OF STEMS. 219 consisting of peculiar cells, called fiast-cetts, of re- markable length and flexibility, and having very thick walls (Fig. 392). They usually form layers like the leaves of a book, and hence this portion of the bark is called the liber. The length and tough- ness of its fibres have led to its use in thread, cord, and cloth. The bundles of bast-cells are always vertical, and are separated by medullary rays, which correspond to those of the woody sys- tem inside the cambium. FIG. 392. FIG. 398. I Fibres of the liber, or bast-cells, and woody fibres from the linden, or bass- wood, are shown in Fig. 393 (Gray), a is a bast-cell, from the bark of Ameri- can basswood, while 5 is woody tissue, from the same tree, showing the upper end of a spirally-marked vessel ; c is a separate cell of the wood. They are all equally magnified. Besides the immensely greater length of the bast- cells, they have also very much thicker walls than the 220 THE SECOND BOOK OF BOTANY. fibrous cells of wood. In leather-wood the bast- cells are even longer than those of basswood, being from % to -J of an inch long, and ^^ o f an i ncn j n diameter, while those of the wood are not more than -j-J-g- of an inch long. Few fibres, however, are as long as those of leather-wood. There are very few plants in which they exceed -% of an inch in length. EXPERIMENT. Strip the bark from various woody twigs, and find the liber. Observe the differences it presents in different kinds of wood. Outside the liber no woody tissue is found, but in very young woody stems this external layer consists of loose, green, cellular tissue. As growth proceeds, this is soon covered with a brown layer of varying hue and thickness, called the corky envelop. The cellular layer, thus covered in, is known as the green or cellular layer. The corky envelop and green layer, taken together, are called suber. EXPERIMENT. Gather the bark of as many differ- ent kinds of trees as you can. Separate the suber from the liber. Find the green layer and the corky layer, and note the differences presented by your collection. You will thus associate in your mind the character of the bark with what you know of the other parts and characters of each kind ex- amined. Passing from the centre out, we have Pith ; Medullary sheath ; Layer of wood ; Medullary rays ; Cambium ; Liber ; Suber, composed of the green layer and corky envelop. What parts of the stem are cellular ? What parts are fibrous and vascular? Do you know which threads are warp and which are woof, in cloth ? If THE STRUCTURE OF STEMS. 221 you liken the stem to a woven fabric, which part of it would you say made up the warp, and which part the woof? EXERCISE LXIX. Second Year's Growth of Dicotyledonous Stems* In annual plants, like the melon, the cambium, of course, perishes when the plant dies ; but in woody plants this is the region of growth for all after-years. You have seen that, in the primitive bundle (Fig. 386), there are two partial bundles, one of tissues belonging to the woody system, and the other of tissues belonging to the bark. The bark and wood are connected by a delicate tissue of actively -mul- tiplying cells, which may be easily seen with the mi- croscope. As these cells are more gorged in spring, the bark and wood are then more easily separable. Now, on the second year this cellular zone forms in its interior, or next the wood, a new layer of wood, precisely as in the former year, by the elongation of some of its cells into fibres, and the conversion of others into vessels, or ducts, while still others form the parenchyma of the medullary rays. On the side of the cambium next the bark there is similarly formed from its cells a second layer of bark, precisely like that of the first year. The new layer of bark and the new layer of wood are, as before, transformed cambium, but they are always separated by the true cambium layer of vitally-active cells. 222 THE SECOND BOOK OF BOTANY. The changes produced by age upon the woody system of the stem, besides its annual addition of a woody layer, constituted as above described, are, first, loss of color of the cells of the pith, which at last dry up, and lose all vitality ; the thickening of the wood-fibres by internal deposit, while, at the same time, they take on a dark color, and become duramen, or heart-wood. Can you see any reason why the yearly layers of wood should form rings so distinct that they can be counted, and the age of the tree determined ? It is because the wood formed in the first part of the year, which is, of course, placed next the old ring, is more porous, and often has a larger number of ducts with large mouths than the wood formed later in the sea- son. This is shown in Fig. 394, where the annual FIG. 394. layers are marked off and numbered, and you see that the inner portion of the layer is more porous than the outer. Now, the new layer of wood is moulded exactly upon the last year's layer, so that the bundles are separated, as before, by the medullary rays, which THE STRUCTURE OF STEMS. 223 are, of course, continuous with those of the former year, and so extend from the pith to the bark. The woody bundles of the second year are more numer- ous than those of the first year. If each newly-added portion of the old woody bundle was undivided, there would be the same number of medullary rays through- out the growth of the stem. But, besides the medul- lary rays that separate the primitive bundles, and ex- tend from the pith to the bark, there arise divisions of each new bundle into two or three parts by series of cells, which are called small medullary rays (Fig. 395). FIG. 395. In this figure, representing four years' growth, you can trace the rays of each successive year. There is only one of the first year's growth, and, by the de- velopment of this portion of the stem, on the fourth year you see fifteen. So that each year, with the for- mation of the new woody layer, new medullary rays are also started, which are prolonged on the following years in the same way as the great rays proceeding from the centre of the stem. 224 THE SECOND BOOK OF BOTANY. In our picture of the woody bundle (Fig. 386) of the first year, the portion next the pith is shown, consisting of spiral ducts; and you saw (Fig. 385) that the spiral ducts of all the woody bundles form a sheath around the pith. But this sheath is not re- produced in after-years. There are no spiral ducts in the wood of the second year. They are never found in woody stems, except around the pith. The stem, then, is made up of two distinct parts, the wood and the bark. Fig. 396 represents a por- FIG. 396. K L. P. L. k LMC.C. F. v. F. v. F.V.T. M tion of a woody stem three years old. At M, you see the pith ; T is the medullary sheath, and Y, F, the woody layer of the first year, followed by Y, F, Y, F, the layers of the second and third years. After the cambium (C) is the green layer of the bark (M C), and the three successive yearly rings of bark, marked L, P, L, P, L, P. The green layer does not increase at all after the first year, as the corky layer shuts out the light on which its growth depends, and finally it perishes en- THE STRUCTURE OF STEMS. 225 tirely. The corky layer continues to grow for a few years, but it differs in different species. Its cells are powdery in the birch, and so cause the peeling of the more compact layers. The liber continues to grow throughout the life of the tree. Fig. 397 represents a vertical and horizontal sec- tion of a woody stem three years old, in which you can trace the parts we have described. FIG. 39T. What must be the effect upon the bark of this yearly formation of two new layers within it ? Examine the bark of such trees as you can get at, and point out the results which you think follow from this internal deposit of matter. In oak and chestnut wood the ducts of the inner portion of each annual layer are large and numerous, while the outer portion of the layer is dense and solid. 226 THE SECOND BOOK OF BOTANY. In inaple and beech the ducts are uniformly dis- tributed, while in pines there are no ducts at all. But the inner and outer portions of each layer are still so different in compactness, that the line which separates the new, large, vigorous cells of the spring growth from the close, fine cells, formed the last of the previous season, can usually be distinctly seen. But, if the wood of pines has no ducts, it still presents a peculiar structure. It is composed wholly of dotted fibres, and the dots are produced by little hollows in the sides of the fibres, like the cavity of a watch-glass, these hollows being so placed FIG. 397.* that, when fibres come together, one concavity answers to another (Fig. 397*), making a lens- shaped space, like two watch crystals, so placed that the concavities face each other. These little disk-like marks are the result of an unequal deposit of the lining material of the fibre, leaving thin places where the wall of the fibres curves inward. This thinness, as the fibre gradually fills up with deposits, pro- duces in the centre of each cup a short canal, opening into its interior. The cavity is usu- ally filled with turpentine, which sometimes finds its way through this canal into the fibre, destroying it little by little, and often producing con- siderable deposits of resin in the wood of green trees. In all the pine family these marks are on the lateral portions of the fibres, and never on the part toward the centre or the outside of the tree. THE STETTCTITKE OF STEMS. 227 FIG. 398. EXERCISE LXX. Stalk of Monocotyledons. The embryo of the monocotyledon is entirely cel- lulai before germination. Growth commences by the elongation of these cells, and the gradual forma- tion of fibro-vascular bundles. At first the bundles are few, and disposed much as in young dicotyle- dons, but, in proportion as the leaves develop, these bundles multiply, and are distributed, without apparent order, all through the cellular tissue; they are, however, much more numerous and solid as they approach the circumference of the stalk. Make an horizontal section of the stem of a corn- stalk, and compare it with Fig. 398, where the dots (F) represent woody bundles, and the spaces (M) represent cellular tissue. FIG. 899. If you examine one of these bundles under the microscope, you will find it presenting an aspect like 228 THE SECOND BOOK OF BOTANY. FIG. 400. Fig. 399. That portion of the bundle which looks toward the centre of the stem answers to wood, and the outer portion answers to the inner bark, while the cellular tissue, through which the bundles are interspersed, answers to the medullary rays and pith of the stems of dicotyledons. In Fig. 399 L is a region of fibres, with thick walls and spiral ducts (T). Then, in the midst of cells and fibres (P), we have barred and dotted ducts (Y); beyond, at L, are thick fibres, like the liber, and, still outside of these, the laticiferous ducts ( V L). The vertical section of a stem formed from these bundles presents an appearance like Fig. 400. These woody bundles, scattered irregu- larly through the cellular tissue, remain single and isolated. There is no such thing as a separation of the stem into a woody system, and a region of bark, with cam- bium interposed, as in dicotyle- dons. There are differences, however, between the central and exterior parts of the stem, somewhat analogous to these, which we will endeavor to ex- plain. Figs. 401 and 402 will assist in understanding these differences. The dark lines represent woody bundles. Each bundle, traced from above downward, starts from a point on the stalk, where a leaf is inserted, descends obliquely toward the centre of the stem (mark this), then, curving out- ward, descends obliquely again toward the circumfer- THE STRUCTURE OP STEMS. 229 ence. You see it crossing successively all the bun- dles situated below it, and older than itself, and taking its place above them. Now, the differences between the interior and exterior of the stem result chiefly from the changes in composition that each bundle under- goes in its course from its origin at the leaf insertion to its ending in the cir- FIG. 402. FIG. 401. cumference far below. In the region of the bundle which descends toward the centre, its woody portion is- greatly in excess over the cortical part, while below this region, in the part of the bundle which descends toward the periphery, the cortical part of the bundle greatly predominates, and finally forms almost the whole of it. On approach- ing the outside, the bundle grows thin, and divides into several filaments, resembling fibrous roots. These filaments interlace with those of neighboring bundles, THE SECOND BOOK OF BOTANY. and form a zone of a sort of netted liber inside the cellular layer, which serves as bark. It is thus apparent that the central part of the stem will always be made up of the part of the woody thread in which the wood predominates. This part of the thread is porous, and contains great ves- sels, so that the centre of the stem is rather cellu- lar and vascular than fibrous. In the same way the peripheral part of the stem always contains, or is made up chiefly of, the part of the thread in which the cortical portion, the bast-cells, or liber, predomi- nate ; it is, therefore, more solid. Outside of this is the region where the spongy bundles split and inter- lace, losing themselves in the bark ; so that an hori- zontal section of a monocotyledon ous stem is made up of a central porous portion, a peripheral colored and dense portion, and a zone of a sort of liber ex- terior to this. In dicotyledons, on the contrary, the old, solid wood is in the centre, or heart, of the stem, and the new, soft wood surrounds it. A monocoty- ledon ous stem presents nearly the same size along its whole length. This is because the woody bundles lessen gradually toward their inferior portion, and are not all collected at the base of the tree, as in dicoty- ledons. In monocotyledons, the new wood is formed in the central part of the stem ; they are hence called endogens, or inside growers, while dicotyledons, which form their new wood in circles outside the old, are called exogens, or outside growers. This is, perhaps, as good a place as any to tell you that all plants that bear their seeds in closed seed-ves- sels may be divided into two great classes, based upon THE STRUCTURE OF STEMS. 231 characters of seed, stem, and leaves. Their seeds are either monocotyledon ous or dicotyledonous. The mo- nocotyledons have stems in which the parts are ar- ranged as we have just shown ; they have the endogen- ous structure, and are hence called endogens. Their leaves are also parallel-veined. The dicotyledons, on the contrary, have stems with the exogenous struct- ure, and are hence called exogens. They have also net- veined leaves. Now, these characters are almost al- ways combined as here stated. There are dicotyledons with parallel-veined leaves, though they are very rare ; but the structure of the stem is characteristic. When you find a plant with a stem having woody bundles surrounding the pith, it belongs to the class of exo- gens ; but, when the woody bundles are seen scattered, without order, through the parenchyma, the plant be- longs to the class of exogens. The coniferae, you remember, are poly cotyledon ous and naked-seeded, but they form their new wood outside the old, and therefore belong to the exogenous class. Among the flowerless plants, minute structure also furnishes characters used in classification. The stems of ferns have a mode of growth peculiar to themselves, which has given them the name of acro- gens, or end-growers, because the new parts are always formed above the old. Mosses, algae, and fungi, are called cellular plants, being made up of nothing but cells. It is not till we come to ferns in the ascending scale of vegetation, that any thing like true vessels and fibres appear. The scheme on the following page will show you how these plant-characters are used in separating the vegetable kingdom into classes : 232 THE SECOND BOOK OF BOTANY. s .a H 4 B ^P ,-i. ! /^ 1 02 W ^ 02 IH OGENS PHYTE 1 1 < | 3 w H of . H ^ > ^. 3 ' S 02 P c5 1 g O cS fehi S 1 1 I *o p 0> "-H g e3 eS S >-, b ^ C g O E "3 ^S O i T3 ^ "> ^ ' to r^ = d fe 8 ~ -g cc CHAPTER XVII. THE ROOT. FIG. 403. EXEECISE LXXI. True Moots and Adventitious Moots. WHEN the young plant contained in the seed be- gins to grow, the plumule rises toward the light, while the opposite portion grows downward, and be- comes root. Observe in Figs. 383 and 384 that the root, as it increases in length, sends off branches on all sides. Roots formed thus, by the extension and branching of the root-end of the embryo, are called true roots. But, in the sprouting of such seeds as the oat or Indian-corn (Fig. 403, from Prof. Gray), the radicle never lengthens; it be- comes abortive, and the roots spring from the side of the stem. All roots that arise from the sides of stems, either in germi- nation, or at any period in the growth of a plant, are 234: THE SECOND BOOK OF BOTANY. called adventitious roots. The roots of all mono- cotyledons are adventitious. Many dicotyledonous plants produce adventitious roots in the course of growth. EXPERIMENTS. Place the branch of a willow with its cut end in the moist ground. It will send out roots, and become an independent plant. Detach a slip of geranium from its parent plant and bury its broken end in moist sand. It will take root, and form a perfect plant. Observe the roots of Indian-corn, that always arise just above the ground, at the joints, and, grow- ing downward, enter the soil. Some plants, as the strawberry, that begin life with true roots, continue it by means of adventitious roots. Bend over the young branch of a rose-bush, and bury a portion of it in the soil (layering). It will attach itself by means of adventitious roots, and then you may cut its connection with the parent -bush without harm. Adventitious roots are often found on the stem of climbing plants, giving support to them by ad- hering to adjacent objects. Only true roots become tap-roots. When the branches of true roots remain small, the central por- tion can thicken ; but, if they are many and vigor- ous, the central portion is lost, and the root becomes fibrous. All the various forms of roots depend upon the amount of the branching and the enlargement of its different portions by deposits of food. THE BOOT. 235 EXERCISE LXXII. The Minute Structure of Hoots. In the germination of dicotyledons the cells of the root-end of the radicle multiply, and the central ones are changed into vessels continuous with those of the stem. The developed root differs from the stem in having neither pith nor medullary rays. Like the stem, its thickness increases by the annual formation of a layer of wood and a layer of bark. Spiral ducts are never found in roots ; such fibres and ducts as enter into its composition are like those found in the stem. Its cells are filled with sap and with starch. In monocotyledons the multitude of fibrous roots, which issue from the side of the radi- cle in germination, are exactly like the stem in their minute structure. Roots grow in length by additions of matter at the tip, or free end, while the stem grows throughout its whole length. You may test this statement by marking off into FIG. 404. four equal divisions, with ink, the parts of the root of a sprouting pea. After leaving it in the soil for three or four days, observe whether the parts have all lengthened to the same extent. It has been calculated that the growth is confined to a space of about one-sixth of an inch from its tip. Fig. 404 represents the struct- ure of the growing extremity of roots and rootlets. The darkened cells (b) are the region of vital activity ; 236 THE SECOND BOOK OF BOTANY. the dead cells (a) at the extreme end form a sort of root-cap, which protects the living point from injury as it pushes its way through the earth. These dead cells are gradually sloughed off, and replaced by the addition of worn-out cells from within. As these root-tips absorb moisture from the soil, they have been called spongioles, though incorrectly. The surface of the growing parts of roots is often densely covered with minute hairs. Fig. 405 repre- sents a portion of barley -root highly magnified, and you see the hairs are tubular elongations of the outer root-cells. They are more abundant in poor than in FIG. 405. FIG. 406. good soils. They wither with age, and are replaced by new ones nearer the extremity of the young- est branches and fibres. Pull up a young radish, and observe its surface. Compare it with A (Fig. 406). Rinse away the dirt, and com- THE ROOT. 237 pare it now with B (Fig. 406). Observe the absence of hairs at the tip. The first formation of roots in plants is quite in- dependent of the medium in which they exist. But, when the roots begin to act, their growth depends very much upon the medium that surrounds them. If there is food, they grow ; and, the more abundant the food, the more they multiply. Those rootlets that come in contact with food, flourish and branch in all directions; while those that find none, cease to grow, or perish. Roots that grow in rich soil are short and very branching ; while in poor soil they are long, slender, and have few rootlets. Most plants with roots adapted to the soil will die if they be left in air or in water ; while water-plants die if their roots are placed in the earth. Yet there are some plants which flourish equally well, whether their roots are in the soil, in swamps and marshes, or in water. For instance, rice will grow in pine-bar- rens, in the tide swamps of the coast, or when its roots are under water throughout its life. If, however, the seeds of many ordinary plants, when sprouted, have their roots placed in water, care being taken to keep the seed and stem in air, and nourishment be supplied to them, they will produce foliage, flowers, and seeds, the same as if grown in the soil ; but, when thus started in water, they will not bear transplanting into soil of the usual dryness. If so transplanted, they may be kept alive by profuse watering until the formation of new roots adapted to the soil. Equal difficulty is met when plants, started in the soil, have their roots placed in water. 238 THE SECOND BOOK OF BOTANY. EXERCISE LXXIII. Duration of Hoots. Roots are divided into classes, according to their duration. ANNUAL ROOTS are those which spring from the seed, and die the same year or season. They are always fibrous, arising from numerous divisions of the main or tap root, or, as in all annual grasses, the root is made up entirely of such fibres proceeding at once from the base of the stem. BIENNIAL ROOTS are those which live through two seasons, dying at the close of the second. You may trace their history in every garden. Plant parsnip- seeds, for instance, which send down their true roots, and form an abundant crown of showy leaves. In the autumn the leaves die, and the tap-roots, filled with nutritious matters, so valuable to man, survive the winter, and in the following spring begin to grow again. But the course of growth is reversed from that of the previous season. Before, it was busy storing up nourishment, which is now spent in form- ing stem, leaves, flowers, and seeds, with the ripen- ing of which the whole plant dies. PERENNIAL ROOTS. These are found in plants which last year after year. In trees and shrubs the same roots live and grow indefinitely ; but in herbs that continue from year to year, the active roots of each season die at its close, leaving a stock of newly- formed roots to perform the work of the succeed- ing seasons. The peony and the horseradish are examples. CHAPTEE XYIII. THE LEAF. EXERCISE LXXIV. The Minute Structure of Leaves. STEMS bear nothing but leaves of some kind or other, for branches are only secondary stems. As leaves are developed upon the stem, we should expect to find them composed of the same elements as the stem. By means of the microscope you may easily determine whether this is so. First examine the structure of the framework of a leaf. Observe a thin horizontal or oblique section, taken from the petiole, midrib, or veins. You will find it composed of fibrous and vascular tissue. Examine a similar slice of the pulp. It consists of cells filled with chlorophyll. The framework is fibro-vascular, while the meshes of the framework are filled with paren- chyma. If you should trace the elements of veins and ribs back into the stem, you would find the upper part of this framework connected with the medullary sheath, and you would note that this upper portion, like the medullary sheath, is largely composed of spiral ducts. The lower portions of the framework that appear on the under side of the leaf, you would find to arise from the bark, and to be continuations of the liber. The ribs of most dicotyledons contain much liber, which makes them project on the lower surface. 11 240 THE SECOND BOOK OF BOTANY. FIG. 407. Are there also differences in the parenchyma of the upper and under sides of leaves ? Make a verti- cal section of the blade of any fresh, ordinary leaf, and observe the structure. Compare it with Fig. 407. Are not the cells much more closely packed on the upper than on the under side ? In the figure you see the upper side, composed of three rows of closely - packed cells, placed end to end, while in the lower half the cells are placed ir- regularly, and the tissue is full of intercellular spaces. You see in this portion of the section the cut- ends of vessels and fibres, where a vein has been severed. This is but one out of many different modes of arrangement ; but, in all such leaves as turn one side toward the sky and the other toward the ground, there will be found more or less difference in the structure of the upper and under portions. Remove a bit of the epidermis, or skin, of a leaf, put it upon the glass, with a drop of water, and examine it with the microscope. Is there any chlorophyll in its cells? How are the cells arranged? Is there more than one layer ? Does your specimen exhibit any such appearances as are seen among the cells in Fig. 408? Examine a fresh bit of skin from the under surface of a leaf, and you will surely find them. They are much larger and more numerous in some leaves than in others. Between and under- neath these two oblong cells there is an opening THE LEAF. 241 through the epidermis into the intercellular spaces of the parenchyma. These thin-walled cells which guard the opening separate when swollen with moisture, and close together, so as to cover it, when dry. They FIG. 408. are called stomata, or breathing-pores. In some plants, as the under surface of the leaves of the white lily, there are about sixty thousand of these stomata to the square inch ; while in the epidermis of the upper surface there are only about three thousand to the square inch. They vary in different plants from less than a thousand to one hundred and seventy thousand to the square inch of surface. Examine the epider- mis from any part of a plant, from the stem, or from sepals, petals, etc. You will often find it furnished with stomata, but you will look in vain for them in the leaves of water-plants. The lower side of the leaf has generally more hairs than the upper side. These hairs are continua- tions of epidermal cells, and vary much in structure. Fig. 409 represents a magnified portion of the epidermis of a cabbage-leaf. The oblong slits are stomata, while the pointed, protruding bodies are 24:2 THE SECOND BOOK OF BOTANY. hairs in different stages of development. One of these hairs, with some of the cells of the epidermis, is shown in Fig. 410. Hairs composed of a single FIG. 409. FIG. 410. cell are sometimes branched, as shown in Fig. which represents a hair of alyssum ; J is a transverse section, which better shows the star-like form of the branching. In Fig. 412 (a) the hair has the appear- ance of cells strung together like beads. FIG. 411. FIG. 412. FIG. 413. Glands are organs that possess the property of secreting ; that is to say, of separating some particu- lar liquid from the juices with which they are in con- THE LEAF. 243 tact. They are cellular, and found in the substance of the epidermis, at the base of hairs, as in stings, or carried on the summit of hairs, as in Fig. 413. Such hairs give to plants an appearance as if covered with little pellucid dew-drops. Look at the hairs of all sorts of plants through the microscope. You will find that glandular hairs are by no means uncommon. Fig. 412 (b) represents a sting. It consists of a sin- gle cell, fixed upon a gland, filled with irritating juices. When the hair is disturbed, the liquid of the gland passes through it, and is injected into the disturbing object. Glands are sometimes buried in the bark, but they are always near the epidermis. Cavities containing gums, resins, etc., are analogous to glands, but buried more deeply in the substance of the plant. Bracts, sepals, and petals, are constructed in the same way as foliage-leaves. Their framework is fibro- vascular, and filled in with parenchyma, which con- tains various coloring-matters instead of chlorophyll ; and over all there is spread a delicate epidermis, more or less studded with stomata. The sepals of mono- cotyledons are parallel-veined, and those of dicotyle- dons are net-veined. When petals have long claws, the fibro-vascular bundles traverse them, and sepa- rate, to form the framework of the limb, which is composed of spiral vessels and elongated cells. If you examine the structure of the filament, you will find it composed of a central bundle of spiral vessels and delicate woody tissue, which terminate in the connective. They are surrounded by a layer of cells, covered by the epidermis. The anthers are en- tirely cellular, the pollen cavities being lined with a 244 THE SECOND BOOK OF BOTANY. layer of annular, spiral, or reticulated cells, which di- minishes in thickness as it approaches the line of de- hiscence. In the structure of a carpel, you find the ovary covered with a double layer of epidermis, enclosing cellular tissue and fibro-vascular bundles that rise from the ovary into the style, not as in the filament at its centre, but at the circumference. The centre of the style is a sort of canal, with cells projecting inward, and its middle filled with moist, cellular fila- ments, called conductive tissue. This tissue also forms the summit of the style, is destitute of any epidermis, and is familiarly known to you as the stigma. The fibres of the pistil end in the placenta, which gives off spiral vessels to the funiculus. These ves- sels terminate in the chalaza of the ovules. Make sections of these parts, and observe the structure for yourselves. Watch the development of young leaves. Ob- serve at what stage of growth the framework be- comes visible ; whether the base or apex is formed first ; when the stipules appear ; when lobes, and the leaflets of compound leaves. How does a leaf look when first visible in the bud ? Has it any thing like a leaf-form? Can you find vessels or fibres in its structure while yet in the bud ? Watch the development of the various organs of the flower as the bud is growing. Observe which of its organs appear first. Note whether the base or apex of the petals is formed first. Where the parts of the calyx and of the corolla are grown together, observe whether the tube or the limb is first formed. In regard to stamens, see whether the filament and THE LEAF. 245 anther appear together or in succession, and, if in succession, in what order. Observe the formations of ovules. A long time before the opening of the flower, you may see a small, round swelling on the placenta, which is the nucleus of an ovule. Soon, around this pimple, there appears a circular rim, which rises toward the summit of the nucleus; and then a second rim appears, growing around the first, and ending by overtaking and sur- passing it. These two sacs are not entirely closed, but they leave a circular opening, known to you as the micropyle. Look carefully with your magnifying- glass for the various parts of the ovule while it is growing, and, if you have a microscope, make sec- tions of it, and study its minute structure. CHAPTEK XIX. THE PLANT IN ACTION. EXERCISE LXXV. Absorption of Food by Plants. As long as a seed is kept dry, the embryo remains unchanged ; but, planted in the soil, under the influ- ence of moisture and warmth, it begins to grow to increase in size and weight, and to develop new or- gans. At the same time, the rest of the seed withers and disappears. It has been used up by the growing embryo, while rooting itself, and opening its leaves to the light and air. The plant now goes on inde- pendently, adding new material to its substance, in- creasing its size and multiplying its organs. Now, how do growing plants get the materials for this increase of substance ? This is done in three ways. The first is known as the principle of capillarity. This is the attraction of surfaces for liquids, which causes the flow of water upward into sponges and porous bodies gener- ally ; and its rise in glass-tubes, with small openings like hairs, and hence called capillary tubes. The spongy cellular tissue, without epidermis, at the tips of roots, is surrounded by moisture, which has de- scended, as rain and dew, through the air and soil, dis- solving, in its passage, the various matters which are the food of plants. Just as the water of your wash- bowl wets the whole towel when a corner has been THE PLANT IN ACTION. 247 carelessly left in it, so this water of the soil, entering by the spongioles and root-hairs, passes from cell to cell, and along the vessels and fibres of which the plant is composed. A second force, which aids in feeding plants, is known as osmose. If you place any porous mem- brane between two liquids of different density, a movement of these liquids through the membrane at once begins. Suppose that, on one side there is syrup, and on the other pure water, there will be a flow in both directions through the membrane ; the water will become sweet, and the syrup will be di- luted. But the amount of flow is much greater tow- ard the syrup than toward the water, and, if the cir- cumstances permit, the action will continue till the liquids on the opposite sides are alike in density. You may observe this effect in the cooking of ber- ries, as currants, for instance. Here the outer mem- brane, or skin, of the fruit is between its internal watery juices and the syrup in which it is stewing. This water passes outward, through the membrane, into the syrup of the stew-pan, in much greater quantities than the syrup passes inward, and so the fruit shrivels. On the contrary, if you take dried currants, in which the juices are concentrated, and the fruit already shrivelled, and stew them in pure water, an opposite action takes place. The berry now receives more water than it loses, swells, and assumes its natural shape. In both these cases the principal movement is that of the pure or less dense liquid toward the denser syrup. This is an example of what is called osmotic action. Now, the cells of plants, like the dried fruit in 248 THE SECOND BOOK OF BOTANY. the water, contain liquids denser than that which surrounds them, and hence the flow is from without inward. When they have thus been filled with water, the liquid they contain is so related to that of the next inner cells that it passes on by osmotic action, thus relieving the outer cells, when they are again ready for a fresh supply from the soil. In this way the ac- tion is kept up, from cell to cell, till the liquid has traversed the entire substance of the plant, from the tips of the roots to the uppermost leaves. The third agent in causing the absorption of liquids by plants is, the evaporation of water by the leaves, and its consumption by the growing buds, which tends to produce a vacuum in the uppermost tissues. So that the principle of suction here comes in play to pump up the materials of the soil into the body of the plant. In germination, the food of the plant is furnished by the albumen of the seed, or by the gorged coty- ledons of the embryo itself, as in peas and beans. This food is changed from the insoluble to the soluble state by the action of warmth and moisture ; is dis- solved, and, by capillary and osmotic action, is carried into the radicle, and used by the growing cells in the development of the plumule and the roots. By the time this supply is exhausted, the growing plantlet is able to live upon material furnished by the soil. Its first food is the starch, and other substances stored up in the seed the year before, and is organic mat- ter. But the substances taken from the soil, dis- solved in water, are carbonic acid, ammonia, and earthy and alkaline salts mineral matters which cannot serve in building up the plant's fabric ; these THE PLANT IN ACTION. 249 are changed from the mineral to the organic state by the plant itself. The root, then, is an important organ of absorp- tion. Its cellular extremities are very permeable, and the water of the soil tends to penetrate them. By the various agencies just explained, it rises, through the cells and ducts, to the top of the plant, and escapes into the air by way of the leaves. Plants are said to absorb carbonic acid, ammonia, and sometimes vapor of water, directly from the air by their leaves, but the point is not well established. EXERCISE LXXVI. Evaporation and Digestion. When the water of rains and dews, with the ma- terials it has dissolved from air and earth, enters the plant, it takes the name of ascending sap. It thick- ens a little as it rises, by dissolving substances con- tained in the cells, and, on reaching the leaves, it undergoes various changes, and a large portion of its water escapes into the air by evaporation. The ra- pidity of its exhalation depends upon sunshine, the warmth and dryness of the air, and the structure of the leaves. A sunflower, with five thousand six hun- dred and sixteen inches of leaf-surface, was found, by experiment, to exhale from twenty to thirty ounces in a day, while it lost only three ounces in a warm, dry night, and none at all on a dewy night. A vine with twelve square feet of evaporating surface ex- 250 THE SECOND BOOK OF BOTANY. haled five or six ounces a day ; and a young apple- tree, with eleven square feet of foliage, lost nine ounces a day. Hales calculated that the force which impels the sap in a vine^in summer-time is five times as great as that which drives the blood through the large arteries of a horse ; but the rate of evaporation has a large share in determining the force of the flow. The influence of evaporation in starting the flow of sap is seen when a plant, with a certain time of leafing, is grafted upon a stock which puts forth its own foliage at a later period. The sap starts with the expansion of the leaves upon the grafted stem, and, of course, earlier than usual. Again, when the branches of a tree are enclosed and warmed in win- ter, so that the buds swell, the sap of the trunk is set in motion to supply the demand. It is chiefly through the stomata that evaporation takes place. Situated in the epidermis, directly over the intercellular spaces, they permit the process when water is abundant, and arrest it when the supply fails. Their agency is of the utmost importance, for, unless the surplus water of the ascending sap is got rid of, the plant cannot digest its food ; and, unless the ac- tion of the sun and air is checked when the supply is limited, it would wither and perish. In dry weather, from lack of moisture, the stomata shorten, straighten, and so close the orifice, and put a stop to evapora- tion ; but, when full of water, they lengthen, curve outward, and open a free passage for the escape of the abundant moisture. In some plants, as the cactus, the skin is so thick and dense that, succulent as they are, they yet live and flourish in dry, hot climates. THE PLANT IN ACTION. 251 As we have before stated, the various inorganic substances, taken from the soil by the roots, and from the air by the leaves, are the food of plants. In the leaf-cells they undergo remarkable and very complex changes, some of which are understood, while others are not, and which it is the proper business of chemis- try to explain. The most important action of the leaf is the reduction of carbonic-acid gas, ammonia, and water, to their elements, which are used for the forma- tion of organic compounds. This may be regarded as the first step in the process of organization, and it takes place in the leaf only under the influence of light. Light is the motive power of the vegetable kingdom, and the countless myriads of expanded leaves are all little machines, upon which it takes effect. Light impels the actions of a leaf as falling water impels a water-wheel. The light is an active force, which is ex- pended upon the leaf, is absorbed, and produces chem- ical decompositions. Carbon, the substance of char- coal, is thus separated from carbonic acid, and is ready to be used in the production of organic compounds, of which it is a universal constituent. The decompo- sition of water and ammonia gives also hydrogen and nitrogen, and these, with oxygen, form the chief bulk of all organized substances. Animals have no such power of creating the or- ganic substances which compose them. So that the whole animal world, and the entire vegetable king- dom, may be said to have their origin in leaves. But it is only th first step that is here taken. After carbonic acid, water, and ammonia, are decomposed, their elements are recombined in new groups under the constructive agency of the plant, and their sub- 252 THE SECOND BOOK OF BOTANY. sequent transformations may go on in all parts of the living structure to which the substances are con- veyed by circulation. It is only in daylight that the initial step is taken in the green leaf; but at all times, by night as well as by day, the internal elaborations and the growth of parts may go on. From this it will be seen that, so far as the air is concerned, plants and animals perform opposite offices. The lung and the leaf antagonize each other. Animals absorb oxygen from the air, and return car- bonic acid to it ; and, as carbonic acid is a poison, if there were no plants in the world, animals would, in sufficient time, contaminate it so that it would be unfit to breathe. But the poisonous exhalations of animals are absorbed by leaves, and destroyed, so that the entire vegetable kingdom acts as a vast purifier of the air. You may very easily observe the powerful influ- ence which light exerts upon plants. Remove a sprouting potato from the dark cellar into the sun- shine ; its pale, watery shoots will quickly begin to turn green. The first effect of light is thus to pro- duce chlorophyll, and this chlorophyll becomes the medium of subsequent changes. Observe whether it is the upper or under surface of leaves which is exposed to the light. Whichever it be, reverse it, and note whether the leaf resumes its former posi- tion. Place a movable plant one growing in a box or pot with an erect stem, in a window, where the sunshine will fall upon it. After a little time observe the attitude of the stem. If you find it bent over toward the light, turn it round, and see if it will bend back again. THE PLANT IN ACTION. 253 EXEKCISE LXXVII. The Circulation of Plants. Although the movement of sap is not, like the flow of blood in animals, along a definitely traceable system of vessels, yet, in the larger plants, experi- ments show that it passes upward by one route and downward by another. In woody dicotyledons, the crude, or ascending sap, rises inside the cambium, and chiefly through the woody bundles of the outer circles of wood, hence called sap-woody the inner por- tion of the tree, or heart-wood, having become so solid as to obstruct its passage. You may find proof of this in many ways. If you remove a ring of sap- wood from the stem of a tree, its branches wither and die, while hollow trees may flourish, and carry on all the processes of life. If you observe trees that have been cut down in spring, you can easily see in what portions the sap is most abundant. This crude sap may be obtained in spring, by making incisions into the sap-wood, from which it will trickle, or some- times even flow in streams. It is nearly colorless, and tastes of the substances it has dissolved from the tis- sues of the tree. In monocotyledons, the rising sap has a much freer and wider course along the scattered bundles of fibro-vascular tissue. The elaborated, or descending sap, passes along the inner layers of the bark, and furnishes the cam- bium with material for the growth of cells, and nour- ishment for the young buds in the axils of the leaves. You may stop its descent by removing a ring of bark from the stem or branch of a tree or shrub, but no wood will be formed below the mutilation. The 254 THE SECOND BOOK OF BOTANY. ringing of fruit-trees is one of the means of increas- ing the product of fruit above the ring. The forma- tion of potatoes may be prevented by ringing the cortical layers of the stem. Tie a band tightly around the bark of a young branch. After a little time the branch swells, and forms a cushion above the ligature, while, below, it preserves its former size. When bark is accidentally rubbed off, the new growth, by which the place is gradually covered, comes from above. In monocotyledons, the elabo- rated sap descends along the fibres of the liber of each of the woody bundles, and in this way furnishes the cambium with nourishing materials. In brief, then, water, containing the dissolved food of plants, is absorbed by the extremities of the roots. It rises through the latest-formed wood to the cellular tissue of the leaves, and is there submit- ted to the action of air and light. Changed to elab- orated sap, it descends by the inner layers of the bark, yielding up, in its course, nutritious material to nourish all parts of the plant, till it reaches the root, from which it started. Such is the course of the circulation in spring, when the leaves are young and active. Later in the season, as the woody tissues are more hardened, the sap rises in the cellular tissue. In autumn, the leaves are obstructed by the deposits of mineral matter, so that sap cannot flow in them ; they dry up, and fall, evaporation ceases, and, with it, the movement of the sap. The so-called spongioles, however, continue to act, and so the tree is gorged with liquid before the winter sets in. This liquid dissolves the various pe- culiar matters deposited in the cells of the plant, and THE PLANT IN ACTION. 255 is ready to flow in spring, when the tree is tapped. As the sap flows from the trunk, the supply is kept up by the action of the roots. EXEKCISE LXXVIII. The Reproduction of Plants. The processes described in the preceding ex- ercises of this chapter are only concerned in the growth of the plant. As they are carried on by the root, stem, and leaves, these parts are known as the organs of growth, or vegetative organs. But the last and crowning act in the life of the plant is the pro- duction of seed, and in this process the flower is the portion immediately concerned. Flowers are hence called the organs of reproduction. The influence of pollen upon the pistil of a flower is called fertiliza- tion. Except in rare instances, unless the ovules of a plant are acted upon by pollen, seeds do not appear. This is proved both by observation and experi- ment. You may prevent the production of seed by cutting away the stigma of the flower before the ripening of the pollen. In the case of ? flowers there is no seed, unless they are accessible to the pollen of <$ flowers. A $ palm-tree, growing in a green-house at Berlin, for twenty-four years had not borne seed ; but when some pollen, sent from a dis- tance by mail, was artificially supplied to the stigmas of the tree, for the first time it bore fruit. Again, for eighteen years it was sterile, and in the same way it 256 THE SECOND BOOK OF BOTANY. was again fertilized by pollen, sent through the post. The date is a dioecious tree, upon which the Eastern countries depend for food. They suspend panicles of <3 flowers near the single $ ones, to insure a crop of the fruit. One of the ways in which these people make war is, to destroy the $ date-trees ; the ? ones are, of course, barren, and famine ensues. The usual time of fertilization is when the flower is most perfect in its colors and fragrance. In the course of Nature there are many ways in which the pollen reaches the stigma. Either the stamens are longest, and it falls upon the stigma below, or, if shortest, the flower droops, as in the fuschia, and then, also, the pollen falls upon the stigma, or it may be thrown upon the stigma by spontaneous jerks of the stamen, or the anthers burst with violence, and so produce the same result. Pollen is also wafted by the winds from flower to flower, or conveyed by in- sects in their explorations for honey. In such plants as orchids, where the pollen is in masses, self-fertili- zation is impossible; the pistil can be acted upon only by pollen brought to it from other plants. By these various means pollen of all sorts is distributed upon all sorts of flowers, but only that of the same, or of nearly-related species, takes effect. You know the structure of pollen-grains, and that the stigma is a mass of moist, cellular tissue, without epidermis. Landed upon this conductive tissue, the pollen-cell absorbs moisture, and its elastic in tine swells, and pushes through the openings, or thin places of the more rigid ex tine, protruding a sort of tube, which grows downward, into the spongy centre of the style, till it reaches the ovary. Here it is met THE PLANT IN ACTION. 257 by the ovules, and comes in contact with the nucleus, through the opening in the coats, at the apex of the ovule (the micropyle). Afterward the embryo ap- pears, just within the micropyle, with its radicle pointing to the orifice. Before fertilization takes place, the ovule prepares for it by the formation, at the summit of the nucleus, of a special cell, called the embryo-sac^ within which the embryo is formed. It is supposed that the contents of the pollen grain pass into the embryo-sac by osmotic action. In the case of cone-bearing trees, the scales turn back, and expose their inner surface at the time when the air is filled with the pollen from the $ catkins, which is thus enabled to act directly upon the naked ovules. Then the scales close down, and remain till the seeds are ripe, after which they again open, and thus permit the seeds to escape. If you make sections of a pistil when the pollen is in perfection with a microscope, you may see these things for yourself. The spectacle of a pollen-covered stigma is one of great beauty and interest, even with a good magnifying-glass. After fertilization, the flower withers, and the vigor of the plant is spent in the growth and perfection of the fruit. REPRODUCTION OF FERNS. All over the lower sur- face of the prothallus (Fig. 352), cellular, pimple-like bodies are formed. These projections consist of four tiers of cells, with a canal running down the centre. They project below the lower surface of the prothal- lus, and, when mature, have an open mouth. The canal leads to a basal cell (embryo-sac). These bodies are the pistillidia or archegonia of ferns. ANTHERIDIA. These also are cellular projections, 258 THE SECOND BOOK OF BOTANY. formed on the under surface of the prothallus, but most abundantly near the centre, among the rootlets (Fig. 352). They are composed of one or two cells, developed from the lower face of one of the cells of the prothallus. Within these cells another is formed, in which soon appear a number of minute vesicles, called sperm-cells. When mature, the top of this antheridial cell falls off, like a lid, and the sperm- cells escape. Each of these, when ejected from the antheridium, emits an anthrozoid, a minute, ciliated body, which has the power of spontaneous move- ment (Fig. 414). It is by the passage of these an- therozoids down the canal of the pistillidia that the corpuscle of the embryo-sac is fertilized. From the embryo thus produced, the young fern is developed, which, at maturity, produces sporanges and spores. EXERCISE LXXIX. The Movements of Plants. It is usually considered that one of the prime dis- tinctions between animals and plants is, that the for- mer have the power of spontaneous motion, while the latter do not. But plants do manifest this faculty in various ways, and in a quite remarkable degree. It is seen in the very simplest forms of plant-life. These are the Algse, the lowest class in the vegetable kingdom, to which sea-weeds and fresh-water confer- vae belong. The mode of reproduction of the algae is obscure ; but, in certain fresh-water kinds, it takes THE PLANT IN ACTION. 259 place by what are called " zoospores," and which are represented in Fig. 414. It appears, from the latest ex- aminations, that these zoospores, which are of extreme minuteness, are of ovoid shape, and are partially or wholly covered with those extremely fine, hair-like FIG. 414. bodies, known as cilia, which have the power of spontaneously vibrating, or lashing backward and forward. They exist upon the surface of animal membranes, and, by their rapid, incessant, whipping motion, they cause the agitation and circulation of fluids upon such surfaces. Now, as soon as these minute zoospores free themselves from the parent- cell, the cilia begin to vibrate with great rapidity, the vibrations being accompanied by a movement of rotation of the cell, and the result is a quick motion of the body through the water, similar to the move- ments of the lower forms of animal life. After the motion has continued from half an hour to several hours, the zoospores settle down, lose their cilia, and give rise, by cell-division, to new organisms, resem- bling the parent. (Some algae have a peculiar undu- latory motion, hence they are called oscillatoria.) In the case of higher plants, there are many capa- ble of peculiar motions, some of which seem to re- 260 THE SECOND BOOK OF BOTANY. semble the sensitive movements of animals. The most remarkable example is that known as the sensi- Fio. 415. tive-plant. Fig. 415 represents a leaf of it, with its leaves expanded, as when undisturbed in sunshine. FIG. 416. THE PLANT IN ACTION. 261 If, now, it be touched by the hand, or the warm breath, the whole leaf is quickly affected, and col- lapses. First, the leaflets close in pairs, bringing their upper faces together, and, inclining forward, then the four outspread leaves approach each other, and, at the same time, the main leaf-stalk turns downward, so that the leaf presents the appearance shown in Fig. 416. Another remarkable instance of sensitiveness in a plant occurs in a case of the Venus's-Flytrap of North Carolina, represented in Fig. 417. It is the FIG. 417. leaf that plays the part of the trap, both in its struct- ure and in its action. The midrib of each leaf plays the part of a hinge, while its upper surface is covered with fine bristles, and its margin is sharply toothed. 262 THE SECOND BOOK OF BOTANY. When the surface is touched, the leaf suddenly closes, like a steel-trap, and, if the intruding substance be an insect, it is immediately imprisoned, as shown in the figure. If nothing is caught, the trap soon reopens of itself, but, if there is a victim, it is held with con- siderable force. This irritability, or sensitiveness, seen in leaves, is not uncommon, also, in the flower. Spontaneous motions occur in the petals of the sundew, and in the lip of the corolla of several of the Orchis tribe. It occurs in the organs of reproduction, and is then connected with the process of fertilization of the ovule. The stamens of the various species of bar- berry exhibit this irritability to a remarkable degree. If touched with a pin, or other object, at the base of the inside filament, the stamen will spring violently forward from its place within the petal, so as to bring the anther in contact with the stigma. In Fig. 418 FIG. 4ia the first position is shown at #, and the second at I. After a time the stamen slowly resumes its position. It might seem as if this arrangement were designed THE PLANT IN ACTION. 263 to secure the fertilization of the pistil from the pollen of its own flower. But this is not so. The move- ment takes place when an insect, in quest of the honey in the glands at the base of the pistil, touches the inside of one of the stamens. The pollen is thus thrown on the insect, which conveys it to the next flower it visits, and, leaving some of it on the stigma, brings about cross-fertilization. Interesting motions, dependent upon contact, are also seen in the tendrils of many climbing plants, which bend and alter the position at the touch. CLIMBING PLANTS. These are of various kinds, and are so common as to be easily found by anybody who will look out for them. When a plant is seen to be- long to this class, the first question, to be considered is, How does it climb upon its support ? Does it twist around it (twining) ? Does it put out fingers, roots, or suckers, for attachment (root-climbers) ? or does it shoot out tendrils (tendril-climbers)? The tendrils of climbing plants exhibit interesting motions, de- pendent upon contact. They bend, and alter their position at the touch. This curling effect, which en- sues from contact, is represented in Fig. 419. The motion consequent on a single touch increases for a time, then ceases, and, after a few hours, the tendril uncurls, and resumes its former position. Tendrils have a tendency to curl round any object with which they come into contact, except other tendrils of the same plant. It has been remarked as curious that, in some exceedingly sensitive plants, the falling of drops of rain on the tendril produces no movement. Ten- drils are contrivances for climbing ; they stretch out in search of support, and move through circuits to 12 264 THE SECOND BOOK OF BOTANY. find points of attachment. When one has secured a hold, it shortens by curling up so as to draw the main FIG. 419. stem nearer to its support, then it rapidly becomes thicker and stronger than before. Tendrils of the bigonia (Fig. 420) are described by Mr. Darwin as having a revolving movement, and, when they grow through a branch, and come into contact with the twig, the points bend in like claws, and the tendril holds on to the twig exactly like a bird when perched. The same naturalist says that the tendrils of this plant will slowly travel over the surface of a piece of wood, and, when the point, or " toe," of one of them finds a hole or crack, it inserts THE PLANT IN ACTION. 265 itself, and it will sometimes, after many hours, with- draw from one fissure, as if it did not find it satis- factory, and seek another. The.re is something won- FIG. 420. derfully like instinct in all this. Prof. Gray remarks : " If we watch the tender passion-flowers which show the revolving so well on a sultry day, we may see with wonder that, when a tendril, sweeping hori- zontally, comes round so that its base nears the par- ent-stem, rising above it, it stops short, rises stiffly upright, moves on in this position until it passes ty the stem, then rapidly comes down again to the hori- zontal position, and moves on so until it again ap- proaches and again avoids the impending obstacle." Observe the structure and watch the movements of tendrils in pumpkin, squash, gourd, and grape 266 THE SECOND BOOK OF BOTANY. vines. "When a tendril has effected an attachment, and both ends are fast, how does it continue to coil ? How do the tendrils of grape-vines move in respect to the light ? In what way do they seize the support ? In what way do the tendrils of the Virginia creeper and ivy attach themselves to walls 2 On a sultry day rub gently, with a stick or with the finger, the whole length of a vigorous tendril, and note the effect, and the time in which it is produced. TWINEES. Some plants rise by twisting around their support, as in the familiar case of the bean, or the hop, or the morning-glory. The extremity of the stem of a bean, which has grown a foot or two beyond its support, will extend from it in a nearly horizontal direction. If its position at a certain time be noticed, and then, if it be observed again some time afterward, it will be found to have changed place, and to point successively in different directions. The end of the stem thus revolves in a circle round its support, and the same kind of plant always turns in the same direction, although some go with the sun and some against it. The twining is, of course, the simple result of revolving in a circle, for, if the stem reaches away, and is arrested at any point by an ob- stacle, the portion beyond continues to move round in the same direction, and, as it lengthens, it of course twines around the impediment. Observe the attitude of a stein of the bean, hop, or morning-glory, that overtops its supports. Mark the position, and observe it again in an hour or 'two afterward. What is the direction taken in each case ? How does temperature affect the result ? Do they move in the night ? Make dots with ink along THE PLANT IN ACTION. 267 the upper side of the outstretched stem, and see if the dots continue in that position. Make a circuit of the garden and grounds in the daytime, and note the appearance and position of the leaves of each of the plants you encounter. Ob- serve the attitude of the petiole and the blade, and the degree of flattening that the leaf exhibits. Note, also, the state of the floral organs. Observe them again in the evening, or at nightfall. Flowers that were open by day, and are now closed, should be ob- served again on the following day, to see if they re- open. If they do, watch them, and discover their times of opening and closing. If they do not, dis- cover, if you can, how long they remain open. Have the leaves of any of the species observed in the daytime assumed a different position ? When certain movements of leaves and petals, as curvature or folding, take place at particular times, and the new position is retained for a certain period, such movements are called the sleep of plants. CHAPTEE XX. COLLECTING AND PRESERVING PLANTS. EXERCISE LXXX. How to gather, press, and mount Plants. FIG. 421. IMPLEMENTS. For your botanical excursions you will need a small trowel for digging roots (Fig. 421), or a large, strong, clasp-knife, that will serve both for digging and for cutting branches ; a strong portfolio, from sixteen to twenty inches long, and ten or twelve inches wide, tied with tape or a strong cord. It should be made of two stout sheets of pasteboard, separated at the back (Fig. 422), and will be all the better if covered with enamelled cloth, to protect it from COLLECTING AND PRESERVING PLANTS. 269 moisture. This portfolio should contain a stock of thin, unsized paper, such as the poorest printing- paper, or grocer's tea-paper, and a close tin box, for preserving specimens, to be examined at home while fresh. Such a box is shown strapped upon the col- FIG. 422. t ' lector, in Fig. 421. It shuts close, and has two com- partments : the large one, with a door in the side, nearly as long as the box ; and a small one, two or three inches deep, with a door in the end, for re- ceiving small, delicate specimens of any kind. WHAT TO GET. Specimens that are intended for preservation must be gathered with great care, and pains must be taken to get average examples of each species. If possible, they should be gathered in dry weather. Herbs should be gathered when in flower and in fruit. They should be taken by the root, and, if it is not too large, this should be pressed, along with the rest, to show whether the plant is annual, biennial, or perennial. Thick roots, bulbs, tubers, and the like, should be thinned with a knife, or cut in slices, lengthwise. Buds and fruit should be ob- tained, as well as the expanded flower. All three may sometimes be found upon the same plant, but 270 THE SECOND BOOK OF BOTANY. generally they will have to be obtained at different times, unless, indeed, you are able to find buds, flowers, and fruit, all at once, upon plants in differ- ent stages of development. Small herbs may be preserved entire. If the radicle leaves are withered at flowering-time, get a younger specimen in which they are fresh. When herbs are too large for this, they may be cut in sec- tions, or folded, or you must be content with branch- es and specimen-leaves taken from near the root. In the case of woody plants, one or more shoots should be taken, bearing leaves, flowers, and fruit. Both sterile and fertile flowers should be obtained from monoecious and dioecious plants. TRANSPORTING. The specimens, when freshly gathered, should be laid between the sheets of the portfolio, the more delicate ones being carefully placed between sheets of drying-paper, so that, on reaching home, they can be transferred to the press without being disturbed. The folds and doublings of leaves and petals of ordinary plants, occasioned by the wind, in the open field, are easily smoothed out when putting the plants in press. PRESSING. As good an arrangement as any for pressing plants consists of two stout boards, that will not warp or bend, between which the specimens are placed, with any convenient weight as stones, or masses of iron, of not less than fifty or sixty pounds laid on the top. Between the plants you put layers of drying-paper. Newspapers answer very well for this purpose. They should be made into packets of about a dozen thicknesses, stitched together. Lay the plants smoothly between these packets. Put COLLECTING AND PRESERVING PLANTS. 271 unsized paper between the parts of a specimen that overlap each other, to prevent moulding, and hasten drying. Be careful to dispose the plants so that they will not lie directly above each other ; keep the top of the pile as level as possible, to equalize the press- ure. The number of packets interposed will depend upon the juiciness of the plants, and must be left to your own judgment. When plants are first put in press, the papers should be changed once a day for three or four days, after which every other day will answer. When the drying packets are changed, they should not be left lying upon the floor, but should be dried upon a line stretched across the room, or in the open air. MOUNTING OF SPECIMENS. When the plants are dry, the next thing is to mount them. For this pur- pose you will need 1. Strong, heavy, white paper, larger than foolscap sheets 1TJ inches in length by 11J inches in width, is a size, on many accounts, de- sirable ; 2. Corrosive sublimate, for poisoning plants, to keep off insects ; 3. Glue, to fasten them upon the paper. Dissolve about an ounce of sublimate in a quart of alcohol. It should be labelled, and kept with great care, as it is very poisonous. A simple way of ap- plying the solution is to pour a little into a large, flat platter, so as to cover the bottom, and " immerse the whole specimen for a second therein." After poison- ing, the specimens are to be laid between driers, and subjected to slight pressure for twenty-four hours, when they are ready to be fastened to the paper. The flowers and tender parts of coarse, tough plants are all that need poisoning. 272 THE SECOND BOOK OF BOTANY. The specimens are to be fastened to the paper with hot glue, about as thick as cream, laid on to the plants with a camel's-hair pencil. Strips of thin, gummed paper should then be fastened over the thicker parts, to prevent their coming loose in han- dling. Prepare your glue in an earthen or porcelain- lined vessel, as corrosive sublimate acts on all com- mon metals, and the brush, passing from plant to glue again and again, will be likely to produce stains if there is a trace of metal in the solution. EXERCISE LXXXI. Labelling and arranging Plants. In some methods of studying botany the scientific name of a plant is the first thing inquired for. But here you have reached the last exercise of the book, and have prepared a collection of plants for receiving labels, while yet ignorant of this part of the subject. It was, however, not the design of the present work to teach you to label plants, with their scientific names, for these are arrived at only by the study of the groups known as genera and species, and they are far too numerous, and are based upon too many combinations of detail in structure, to make it possi- ble to deal with them in a text-book like this. Be- sides, in the true order of study, naming follows, and depends upon classification. You have already done something in this direction. You know the charac- ters upon which classes are founded, have studied a COLLECTING AND PEESEEVING PLANTS. 273 few natural orders, and have begun to consider the affinities of plants. E"ow, classification, from begin- ning to end, consists in associating plants by these affinities, and can be rationally performed only when they are perceived. The reason for a plant's scientific name is found in its predominating affinities. Intel- ligently to label your plant, therefore, you should be so familiar with its assemblage of characters and re- lations to other plants, that you can see why it is placed here, and not there, in the established arrange- ment. The work you have begun now requires a regular botanical manual to carry it out. There are various books that may be used for this purpose, but Gray's "Manual of the Botany of the Northern United States " may be commended as a most excellent work for the purpose. It gives a full statement of the characters of each order, followed by a description of the genera it contains, and then the peculiarities of the species of each genus are fully given, so that a plant is easily identified. The genus and species determine the scientific name. "When you have had some experience in tracing the ordinal, generic, and specific characters of plants, you will read, with profit and pleasure, the chapter of the u Manual " upon classification, and be prepared fully to under- stand the system by which plants are named. AN EXPLANATION OF THE ABBREVIATIONS USED IN THE BOTANICAL CHARTS. Seven principal references are made with a Capital Letter, to J)e looked, for below each Illustration ; and the subordinate parts are then noted by small letters. A reference within a O implies not magnified ; C on the left indicates a Longitudi- nal Section, and <~^ above, a Transverse. L Leaf. Fl. Flower p petiole. 1 limb. 1. 1. .. leaflet. s stipule. f. r. . . -ph.... ph. 1. . ca ca. s. . floral receptacle, perianth, leaves of. calyx, sepals. I. fl. Inflorescence (in flower). I. fr. Infructescence (in fruit). - p. peduncle. - p. p. pedicel. - b. bract. - b. g. ( glume. - b. p. ( pale. - g. r. general receptacle, co. . . . co. p . s s.f. .. S: C. . . s. p. . . pi. ... pi. ca . o corolla, petals, stamen, filament, anther, connective, pollen, pistil, carpel, ovary. ^E ^Estivation (diagram), green. . . sepals, red . petals o. cl. . o. d. . o. pi. . f cell of. dissepiment, placenta. yellow . . stamens, brown . . carpels, blue. . . . ovules, shaded. . adhesion of whorls. sty. . . sti oo. . . . oo. rh. style. stigma, ovule, raphe. 276 EXPLANATION OF ABBREVIATIONS. Fl. oo. ch. 00. f. . n. chalaze. foramen, nectary. S -in.... fq Seed, integument. ( fptstn tg.... ] tegmen. Fr.. Fruit. h - m hile. mvcropvle pe. . pericarp. rh. rap he ep.. . . me. . . en ( epicarp. < mesocarp. ( endocarp ch .... ar. . . . al . chalaze. arillode. albumen ca.. carpel. pe v valve. pe. cl. . pe. d. . . P6 D. . . cell. . . dissepiment, placenta. E ca Emhryo. caulicle. pe. f. . funicular cord. pe. f. a. . . arillus. -pi. ... plumule. GLOSSAEY. AC'CESSOBY, or ANTHOCAB'POTJS FEtrrre. Those formed by the union of many separate flowers. ACCUM'BENT COTYLE'DONS. Having the radicle folded against their edges. ACHE'NIUM. A small, indehiscent peri- carp. ACHLAMYD 'EDITS. Having no protective organs. AO'BOGENS. End-growers. ADHE'SION. The growing together of different floral whorls. AD 'NATE, or DOESTFIXED (anther). With the filament running up the back of the anther. -