Copyriglitl^"- CDEmRIGHT OEPOSni THE BOTANY OF CROP PLANTS ROBBl N S THE BOTANY OF CROP PLANTS A TEXT AND REFERENCE BOOK BY WILFRED W. ROBBINS, Ph. D. PROFESSOR OF BOTANY, COLORADO AGRICULTURAL COLLEGE ILLUSTRATED PHILADELPHIA P. BLAKISTON'S SON & CO 1012 WALNUT STREET x^"^ ^ '^^ Copyright, 1917, by P. Blakiston's Son & Co. I ^ OCT -5 1917 a- r^ ►' t r /^ THE MAPLE PRESS YORK PA PREFACE This book has grown out of a course of instruction ex- tending over a number of successive years. Most of the material presented here, except Part I, has been used in mimeographed form in college freshmen classes, not only as a text from which to make assignments, but also as a guide and reference in the laboratory. The issuance of the book has been stimulated in part by the expressed need of a number of schools for a text and reference book which will give the student a knowledge of the botany of common orchard, garden and field crops, and it is the author's wish that the material brought together from many sources and organized in the present form will meet this need, at least in a measure. It has seemed advisable to include chapters (Part I) which may be needed in some instances to refresh the student's knowledge of certain fundamentals, or prepare him for that which follows in Part II. But in many schools Part II will be preceded by a general course which aims to give the stu- dent a survey of the plant kingdom and an acquaintance with the large outstanding facts and principles of botany, and in this case Part I will be omitted. ■ The subject matter of Part II is sufficient for a course of one-half year involving one recitation and two laboratory (5) periods per week. In the preparation of the book, the writer has had in mind non-agricultural as well ats iagricilitural schools, for it cannot escape notice that there is a growing tendency, wherever botany is taught, to tie it up more closely with economic interests and to draw more and more upon economic plants in citing examples and in choosing objects of study in the laboratory. VI PREFACE The bibliographies are obviously incomplete. Most of the titles were made use of by the writer in the preparation of the manuscript, and to the authors of these he is under obhga- tion. Bailey's Cyclopedia of Horticulture has been indis- pensable and has been called into use frequently. The writer has also called upon the pubHcations of the United States Department of Agriculture and of the various Experi- ment Stations. A number of the "keys" are original, many are adapted, and a few are taken verbatim. A majority of the illustrations are original. It is believed that the direct method adopted herein of labeling drawings will appeal to both students and teachers. Almost all original illustrations, and also those copied or adapted are the work of Mr. N. Lee Foster. The writer is especially indebted to him, not only for the delineation, but for his helpful interest and valued cooperation throughout. Professor D. W. Frear, formeily Associate Professor of Agronomy at the Colorado Agricultural College, now of the North Dakota Experiment Station, is to be given credit for organizing and writing up portions of Chapters IX, XVII, XXX and XXXVIII. The text was planned and outlined by Professor Frear and the undersigned as joint authors, but unavoidable exigencies m.ade it impossible for him to continue his connection .as author. The entire manuscript was painstakingly read by Louise Falk Robbins, and her suggestions have added greatly to the accuracy in many places. W. W. Robbins. Colorado Agricultural College. CONTENTS PART I CHAPTER I.— The Seed Plant B(3dy. Principal Parts of the Seed Plant Body — Size and Form of the Seed Plant Body 1-3 CHAPTER II. — Fundamental Internal Structure of Plant Body. Organs and Tissues — The Plant Cell — The Cell as a Unit of Structure — The Cell as a Unit of Plant Activity — The Struc- ture of the Plant Cell— The Cell Wall— Plastids— Nucleus- Protoplasm 4-9 CHAPTER III.— Roots. Development of Root Systems — The Work of Roots — Effect of Environment upon Character of Root System — General Characteristics of Roots — Classification of Roots Based upon Their Medium of Growth — Structure of Roots — Root Hairs, the Absorbing Organs of a Plant — Root-hair Zone — Structure of a Root Hair — ^Efifect of External Factors upon Develop- ment of Root Hairs — Length of Life of Roots 10-21 CHAPTER IV.— Stems. Development of Shoot System — Buds — Classification of Buds — Bud Variation — General Characteristics of Stems — How Does a Stem Grow in Length — Classification of Stems Based upon Their Medium of Growth — "Modified" Stems- Structure of Stems — The Young Dicot Stem— -Dicot Vas- cular Bundle — Growth in Thickness of Dicot Stem— Monocot Stems — Annual Rings — Bark — The Work of Stems 22-41 CHAPTER v.— Le.wes. Development of Leaves — Parts of Leaf — Kinds of Leaves — Structure of Leaves — The Work of Foliage Leaves 42-47 CHAPTER VI.— Flowers. Parts of Representative Flower — Development of the Flower — Stamens — Mature Pollen Grain — Pistil — Ovule — Pollina- tion — Fertilization — Placentation — Symmetry of Flower — • Relative Positions of Flower Parts — Union of Flower Parts — Incomplete Flowers— Inflorescence 48-56 CHAPTER VII.— Fruits, Seed, and Seedlings. Development of the Seed — Development of the Fruit — Fruit and Seed Distinguished — Kinds of Fruits — Germination of the Seed 57-59 vii VIU CONTENTS CHAPTER VIII. — The Classification and Naming of Plants. Reproductive versus Vegetative Organs in Classification — Groups of Plants — The Plant Kingdom — Plant Nomenclature — Scientific Name — Scientific Name versus Common Name — General References 60-67 PART II CHAPTER IX.— Gramine^ (Poace^) Grass Family. Habit of Plants — Roots — Stems — Lodging — Tillering — Bulb- ous Grasses — Rhizome-bearing Grasses — Stoloniferous Grasses — Leaves — Growth of Leaves — Scales and Bracts — Ligule — Auricle — Inflorescence — Spikelet — Pollination — Fruit • — Phylogeny of Grasses — Grass-like Plants — References — Cereals — Key to Groups of Important Cereals — Key to Small- grain Seedlings — References 68-90 CHAPTER X.— Triticum (Wheat). Habit of Plant- — -Roots — Stems — Leaf — Inflorescence — Spike- let — Flower — Opening of Flower and Pollination — Artificial Cross Pollination — Fertilization and Maturing of Grain — Ripening Stages — The Mature Grain — Relative Proportions of the Parts of the Grain — "Hard" and "Soft" Wheats — Milling of Wheat — Kinds of Flour — Germination of Wheat — Classi- fication of the Types of Wheat — Key to Economic Types of. Wheat — Origin of Wheat — Environmental Relations — Uses of Wheat — Production of Wheat — References 91-121 CHAPTER XL— AvENA (Oats). Habit of Plant- — Roots — Stems — Leaf — Inflorescence — Spike- let and Flower — Opening of Flower and Pollination — Fertiliza- tion and Maturing of Grain — The Mature Grain — Germina- tion of Oats — Classification of Oats — Other Cultivated Oats — A vena fatua ("wild oats") — Origin of Oats — Environmental Relations — Uses of Oats — The Production of Oats — References 122-134 CHAPTER XII.— Hordeum (Barley). Habit of Plant, Roots, Stems, Leaves — Spikelet and Flower — - Opening of Flower and Pollination — Fertilization and Matur- ing of Grain — Mature Grain of Barley — Color of Grain — Germination of Barley — Classification of Barleys — Origin of Cultivated Barleys — Environmental Relations — Uses of Barley — The Brewing Process — Production of Barley — References i35~iS2 CONTENTS IX CHAPTER XIII.— Secale cereale (Rye). Habit of Plant, Roots — Stems, Leaves — Inflorescence — Spike- let — Opening of Flower, Pollination and Fertilization — Matur- ing of Grain, and Mature Grain — Germination of Rye — Classification, and Origin of Rye — Environmental Relations — Uses of .Rye — Production of Rye — References 153-156 CHAPTER XIV.— Ze A (Corn, Maize). Habit of Plant, Roots — "Prop" and "Brace" Roots — Stem — Leaves — Inflorescence — Staminate Inflorescence — Stami- nate Spikelet — Pistillate Inflorescence — Pistillate Spikelet — Hermaphroditic Flowers — Opening of the Flowers, and Pollina- tion — Fertilization, and Development of the Grain — Xenia in Corn— Variation in the Corn Plant — Results of Self-fertiiiza- tion in Corn — The Mature Grain of Corn — Corn Starch Distinguished from the Other Common Starches — Germina- tion of Corn — Classification — Key to "Species Groups" of Corn — Origin of Maize — Environmental Relations — Uses of Corn — Production of Corn — References 157-190 CHAPTER XV. — Andropogon Sorghum (Sorghums). Habit of Plant, and Roots — Stems and Leaves — Inflorescence — Spikelets and Flowers — Fertile Spikelet — Staminate Spike- let — Opening of Flowers and Pollination — Fruit— Varieties- Key to Principal Groups of Sorghum — Origin of Sorghums — Environmental Relations — Uses of Sorghums — References. . 191-201 CHAPTER XVL— Oryza sativa (Rice). Habit, Roots, Stems, Leaves — Inflorescence and Spikelet— Pollination and Fertilization — Grain — Milling of Rice — Varie- ties — Distribution, and Closely Related Species — Uses of Rice ■ — Environmental Relations — The Production of Rice — References 202-209 CHAPTER XVIL— Millet. Key to Principal Economic Types (Species) of Millet and Some Closely Related Common Weed Grasses 210-21 1 Pennisetum glaucum (Pearl Millet) — Stem — Leaf— Inflores- cence — Spikelet and Flower — Pollination — Mature Grain — Varieties — Origin 211-213 Panicura miliaceum (Proso, Hog or Broom-corn Millet) — Stem — Leaf — Inflorescence — Spikelet and Flower — Pollina- tion — Mature Grain — Varieties^Origin 213-216 Chaetochloa italica (Foxtail Millets) — Steam— Leaf —Inflores- cence — Spikelets and Flower — Pollination — Mature Grain- Types and Varieties of Foxtail Millet — Key to Principal Types of Foxtail Millets (Cha;tochloa italica) — Origin of Foxtail Millet 216-219 X CONTENTS Echinochloa Crus — galli (Barnyard Grass or Barnyard Millet) — Habit, Stems, Leaves — Inflorescence, Spikelet, Flowers, and Fruit — Distribution 219-220 Echinochloa frumentacea (Japanese Barnyard Millet) 219-220 Environmental Relations — Uses of Millets — References 220-221 CHAPTER XVIIL— Phleum pratense (Timothy). Description — Environmental Relations — Closely Related Spe- cies — References 222-224 CHAPTER XIX. — Saccharum officinarum (Sugar Cane). Habit, Roots — Stems — ^Leaves — Inflorescence, Flowers, Fruit — Geographical- — Sugar from Sugar Cane — Production of Cane Sugar 225-228 CHAPTER XX.— Liliace^ (Lily Family). Habit, Roots — Leaves — Inflorescence and Flowers — Fruit and Seeds 229-230 Allium — Roots — Stems — Leaf — Inflorescence — Flower — Polli- nation — Fruit — Germination of Seed, and the Seedling — Geographical — Key to the Principal Cultivated Species of Genus Aflium 231-237 Allium sativum (Garlic) 237 Allium porrum (Leek) 238 Allium schoenoprasum (Chives or Gives) 238 Allium ascalonicum (Shallot) 238-239 Allium fistulosum (Welsh Onion or Ciboule) 239-240 Allium cepa (Onion) — Description — History — Types of Onions — Foreign and Domestic Onions — Composition of Onions — • Uses of Onions 240-244 Asparagus — Generic Description — Economic Importance of Genus 244-246 Asparagus officinalis (Asparagus) — Roots — Stems — Leaf — Flower — Pollination — Fruit — Geographical — Types and Va- rieties — References 246-251 CHAPTER XXL— MoRACE-E (Mulberry Family). Description — Key to Principal Genera 252-253 Morus (Mulberry) — Habit, Stems — ^Leaves — Inflorescences — Fruit — Other "Mulberries" — Geographical— Key to Principal Species of Genus Morus 253-255 Morus alba (White Mulberry) — Description — Geographical — Types and Varieties — Economic Importance — Early At- tempts in the United States to Grow Silk — Uses 255-257 Morus nigra (Black Mulberry) — Description — Geographical — Varieties — Uses 257-258 Morus rubra (Red Mulberry) — Description — Geographical — Varieties and Uses 258 CONTENTS XI Humulus (Hop). Humulus lupulus (Common Hop) — Root — Stems — Leaves — Inflorescences— Flowers^PoUination, Fertili- zation, and Development of the "Hops" — The Mature Fruit — Lupulin Glands — Geographical — Closely Related Species — Varieties — Composition — Uses of Hops 258-267 Ficus (Fig) — Habit, Roots, Stems — ^Leaves — -Inflorescence — Geographical Distribution, and Economic Importance 267-269 Ficus carica (Common Fig) — Habit of Plant, and Stem — Leaves — Inflorescence, and Flowers — Pollination — Crops of Fruit in Caprifigs — Caprification — The Mature Fruit — Geo- graphical — Types of Figs — Uses of Figs 269-276 Cannabis sativa (Hemp) — Description — Geographical — Varie- ties — The Hemp Industry in the United States — Preparation of Hemp for Market — Uses of Hemp — Sisal Hemp^ References 276-283 CHAPTER XXII. — PoLYGONACK* (Buckwheat Family). Stems — Inflorescences — Flowers — Fruit — Key to Principal Genera 284-286 Rheum rhaponticum (Rhubarb, Pie Plant) — Roots, Stems, Leaves, Flowers — Fruit — Geographical, and Varieties — Uses 286-289 Fagopyrum vulgare (Common Buckwheat) — Roots — Stems — Leaves — Inflorescence — Flowers — Dimorphism and Pollina- tion — Fruit-^Seed — Geographical — Other Species — Varieties — Key to Varieties of Common Buckwheat — Environmental Relations— Uses — References 289-295 CHAPTER XXIII. — Chenopodiace^ (Goosefoot Family). Habit, Stems, Leaves — Inflorescence and Flowers — Fruit — Key to Principal Genera 296-298 Spinacia oleracea (Spinach) — Description — Other Plants Named "Spinach" — Groups of True Spinach — Key to Groups of Spinach 298-300 Beta vulgaris (Beet) — Botanical Groups — The Wild Beet. . .300-301 Sugar Beet — Habit — Root — Stems — Shape and Structure of Beet (Tap Root and Hypocotyl) — Leaves — Inflorescence — Flowers — Pollination and Fertilization — Fruit and Seed — Seed Production — Germination, and the Seedling — T\'pes of Sugar Beets — Composition of Sugar Beets — Manufacture of Sugar — By-products of Manufacture 301-309 Common Garden Beet — Types — Uses 310-312 Chard 312-313 Mangel-wurzels or Mangels — Types — Composition and Uses— References -S^S'S^S Xll CONTENTS CHAPTER XXIV. — Grossulariace^ (Gooseberry Family). Stems— Leaves — Inflorescence and Flowers — Pollination — The Mature Fruit — Seeds — Geographical — Key to Important Species of Genus Ribes 316-319 Currants — Species — Uses 320-321 Gooseberries — Species — Uses 321-322 CHAPTER XXV.— Crucifer^ (Mustard Family). Stems, Leaves — Inflorescence and Flowers — Fruit — Seeds — Closely Related Families — Key to Principal Genera 323-326 Brassica — Generic Description — Pollination — Seedling — Geo- graphical — Key to Principal Species of Genus Brassica 327-328 Brassica oleracea (Cabbages, etc.) — Wild Cabbage — Cultivat- ed Types of Cabbages — Key to Cultivated Types of Cabbage. 328-330 Brassica oleracea var. viridis 330 Brassica oleracea var. gemmifera (Brussels Sprouts) — Types —Uses SS'^So'^ Brassica oleracea var. capitata (Common Head Cabbage) — Types — Key to Types of Head Cabbage — Uses 331^-33^ Brassica oleracea var. caulo-rapa (Kohlrabi or Turnip-rooted Cabbage) 333 Brassica oleracea var. botrytis (Cauliflower, Broccoli) 334-335 Brassica rapa (Turnip) — Description — Geographical — Types of Turnips- — Structure and Uses 335^337 Brassica campestris (Rutabaga or Swede Turnip) — Descrip- tion—Uses 337-338 Brassica napus" (Rape) — Description — Varieties and Uses. . 338-339 Brassica nigra (Black or Brown Mustard) — Description — • Related Species — Uses 339-340 Brassica alba (White Mustard) 340-341 Raphanus sativus (Garden Radish) — Habit — Root — Stem — Leaves- — Inflorescence and Flowers — Fruit — Seeds and Seed- ling^ — Geographical Distribution and Origin — Closely Related Species — Types of Radishes . 341-344 Radicula (Water Cress and Horse-radish) 344-345 Radicula armoracia (Horse-radish) — Description — Geograph- ical — Uses 345 Radicula nasturtium-aquaticum (Water Cress) — Description ' — Geographical — References 345-347 CHAPTER XXVI.— ROSACE.E (Rose Family). Leaves — Inflorescence — Flowers — Fruit — Key to Important Genera of Rosacea: 348-350 Rub us (Raspberry, Blackberry, Dewberry) — Stems — Propagation — Leaves — Inflorescence — Flowers — Pollination — CONTENTS Xlll Fruit — Geographical — Classification — Key to Groups of Genus Rubus 350-354 Blackberries— Key to Species of Blackberries— Rubus nigro- baccus— Rubus nigrobaccus X R. villosus— Rubus argutus — Rubus cuneifolius 354~3SS Dewberries — Key to Principal Species of Dewberries— Rubus trivialis — Rubus invisus — Rubus vitifolius — Rubus villosus. -355-357 Raspberries — Key to Principal Species of Raspberries — Rubus occidentalis — Rubus idieus — Rubus strigosus — Rubus stri- gosus X R. occidentalis— The Loganberry— Mayberry 355^358 Fragaria (Strawberry) — Roots and Stems — Leaves — Inflores- cence and Flowers — Fertilization, and Development of the Fruit — The Mature Fruit— Geographical — Principal Fruit- bearing Species — Key to Principal Species of Fragaria — Fragaria virginiana — Fragaria vesca — Fragaria chiloensis — Varieties — Origin of New Varieties — Uses— References 358-365 CHAPTER XXVII.— Pomaces (Apple Family). Habit, Leaves — Inflorescence — Flowers — Fruit — Geographical — Key to Important Genera of Pomacese 366-367 Malus (Apples) — Stems — Leaves^Inflorescence — Flowers and Their Development — Pollination and Fertilization— Self- sterility and Self-fertility — Effects of Strange Pollen — Par- thenocarpy — The Fruit and Its Development— Key to Principal Species of Malus — Malus fioribunda — Malus baccata — Malus angustifolia — Malus coronaria — Malus ioensis —Malus soul- ardii — Malus sylvestris — The Classification of Apples — Com- position — Cider and Vinegar — Dried Apples — Production of Apples in the United States ; 367-384 Pyrus (Pear) 384 Pyrus communis (Common Pear) — Stem — Leaves and Flowers — Fruit — Geographical 385 Pyrus serotina culta (Sand, Japanese, or Chinese Pear) — Self -sterility in Pears — Dwarf Pears ' 385 -387 Cydonia (Quince) — Cydonia oblonga (Common Quince)— Stem — Leaves — Flowers — Fruit — Varieties — Uses — Refer- ences 387 390 CHAPTER XXVIIL— Drup,\ce^ (Plum Family). Habit, Stems — Leaves— Flowers — Fruit 391-394 Prunus — Key to Main Groups of Genus Prunus 394 Plums — Stems — Leaves — Inflorescence — Flowers — Fertiliza- tion — Fruit — Classification of Plums — Key to Principal Species of Plums 394-397 Discussion of Species — Prunus domestica — Prunus insilitia — XIV CONTENTS Prunus cerasifera — Prunus triflora — Prunus americana — Prunus hortulana — Prunus nigra — Prunus angustifolia 398-401 Cherries — Description — Groups of Cherries 401-402 Prunus avium (Sweet Cherry) — Description — Geographical — Groups of Sweet Cherries 402-403 Prunus cerasus (Sour Cherry) — Description — Geographical — Groups of Sour Cherries — Other Species of Cherries — Uses . . . 403-405 Apricots — Stems — Leaves — Inflorescence and Flowers — Fruit — Description — Other Species — Uses 405-407 Peaches — Stems — Leaves — Inflorescence and Flowers — Fruit — Geographical — Types of Peaches — Uses, and Production of Peaches in the United States 407-410 Almonds — Description — Types of Almonds — Uses^Almond Oil — References 410-412 CHx\PTER XXIX.— Leguminos^ (Pea Family). Root Tubercles — Habit — ^Leaves —Inflorescence — Flowers — Fruit — Seeds — Key to Principal Genera of Leguminosae. . . .413-417 Pisum (Pea) — Description — Types of Peas— Peas and Men- delism — Uses 417-421 Phaseolus (Bean) — Description — Geographical, and Species — Key to Principal Species of Phaseolus 421-424 Phaseolus lunatus (Sieva and Lima Beans) — Classification of Types of Lima Beans — Table Showing Relationship of Types of Lima Beans 424-426 Phaseolus vulgaris (Kidney Bean) — Uses of Beans 426 Vicia (Vetch, Broad Bean) — Generic Description — Geographi- cal — Key to Important Species of Vicia — ^Less Common Species . . . . : 426-429 Vicia faba (Broad Bean, Windsor Bean) 429 Vicia sativa (Common Vetch or Tares) — Uses 429-430 Vicia villosa (Hairy, Russian, Siberian, or Villous Vetch) . . . .430-432 Lathyrus (Vetchling, Wild Pea) 432 Trifolium * (Clover) — Generic Description — Geographical — Key to Principal Species of Trifolium 432-433 Trifolium repens (White or Dutch Clover) — Description — ■ Geographical, and Uses — Environmental Relations 433-434 Trifolium hybridum (Alsike, Alsatian, or Swedish Clover)^ Description — Geographical, and Uses 434-435 Trifolium incarnatum (Crimson, Scarlet, or Italian Clover) — ■ Description — Geographical, and Uses — Environmental Rela- tions 435-436 Trifolium pratense (Common Red or Purple Clover) — Habit, Stems, Roots — Leaves — Inflorescence and Flowers — CONTENTS XV Fruit — Pollination — Geographical — Environmental Relations — Mammoth Clover — Uses 436-440 Trifolium medium (Zigzag, Medium Red, White, Mammoth or Meadow Clover) 441 Medicago (Medics) — Generic Description — Geographical — Key to Principal Species of Medicago 441-442 Medicago sativa (Alfalfa, Lucerne) — Roots— Stems — "Cut- tings" of Alfalfa — Leaves — Inflorescence — Flowers — Pollina- tion — Factors Affecting Seed Production — Fruit — Germina- tion and Seedling — Geographical — Types of Alfalfa — Environ- mental Relations- — Uses and Production 442-449 IMedicago lupulina (Hop Clover, Black Medic, Yellow Trefoil). 449 Medicago arabica (Spotted Bur Clover) 449-451 Medicago hispida (Toothed Bur Clover) 452 Melilotus (Sweet Clover) — Generic Description- — Species of Melilotus 45 2-454 INIelilotus alba (White Sweet Clover) — Description 454 INIelilotus officinalis (Yellow Sweet Clover) — Description — Environmental Relations — Uses of Sweet Clovers) 454-455 Soja (Soy Bean) — Generic Description 455-456 Soja max (Soy Bean, Soja Bean, Coffee Bean)^ — -Description — - Uses 456-458 Vigna (Cowpea and Related Species) — Description — Species..4s8-46o Vigna sinensis (Cowpea) — Description — Environmental Rela- tions — Uses 460-462 Arachis hypogoea (Peanut, Goober) — Habit, Stem — Leaves- Flowers — Development of Fruit — Fruit — Types — Environ- mental Relations 462-465 Less Important Legumes 465-467 References 467-468 CHAPTER XXX.— Linages (Flax Family) Habit, Stem, Leaf — Inflorescence and Flowers — Fruit — The Names Derived from "Linum" — Geographical, and Environ- mental Relations 469-470 Linum usitatissimum (Common Fla.x)— Habit, Root — Stem — ■ Flax P'ibers — Leaves, Inflorescence and Flowers — -Pollination — Mature Fruit — Seeds — Geographical — Types and Varieties — Uses — Preparation of Flax Fiber — Production of Flax. . . .470-474 CHAPTER XXXI.— RuTACE^ (Rue FAmLv). Description — Key to Important Genera of Rutaces 475-476 Citrus (Citron, Lemon, Orange, etc.) — Habit, Roots— Leaves — Flowers — Pollination and Fertilization — Fruit — Seeds — Geographical — Key to Principal Species of Citrus 476-480 XVI CONTENTS Citrus medica (Citron) — Description — Geographical^" Cit- ron" 480-481 Citrus limonia (Lemon) — Description — Geographical — Color of Lemon Fruit — Uses 481-483 Citrus aurantifolia (Lime) — Description— Geographical— "Limequat " 483 Citrus sinensis (Common or Sweet Orange) — Description — Geographical^ — Types — Uses 484-485 Citrus nobilis (King Orange) — Description — Varieties 485 Citrus grandis (Grapefruit, Pomelo, Shaddock) — Description — Geographical — Variety and Name ^ 485-487 Citrus aurantium (Sour or Seville Orange) — -Description — Geographical — Other Species of Citrus 487 Fortunella (Kumquat or Kinkan) — Description — Species — Uses 487-489 Poncirus (Trifohate Orange) — Description — A Hardy Orange.489 References 489-490 CHAPTER XXXn.— ViTACE^ (Grape Family). Family Description — Geographical — Key to Important Genera 491-492 Vitis (Grape) — Stems — Leaves — Inflorescence and Flowers — Opening of Flower and Pollination — Self-sterihty — Grape Pollen — "Coulure" of Muscat Grape — Flowers of Wild Grape — Key to Most Important Species of Vitis — Vitis vinifera — Vitis rotundifolia — Vitis rupestris — Vitis riparia — Vitis aesti- valis^ — Vitis labrusca — Varieties of Table Grapes — Wine and Raisin Grapes — Uses — References 492-504 CHAPTER XXXIIL— Malvace^ (Mallow Family). Habit — ^Leaves — Flowers — Fruit and Seeds — Geographical- Economic Importance — Key to Important Genera of Mal- vace£e 505-508 Gossypium (Cotton) — Habit of Plants, and Roots — Stems — Leaves — Flowers — Pollination, Fertilization, and Development of the Fruit — Fruit — Seeds — Cotton Fibers Distinguished from Other Common Textile Fibers — Species — Wild Cottons- American Cottons — Types and Varieties — Environmental Relations — Picking and Ginning of Cotton — Bleaching of Cotton — Uses of Cotton — Importance and Production of Cotton 508-527 Hibiscus esculentus (Okra, (Jumbo) — Description — Geo- graphical — Types— Uses 527-528 References 528-529 CONTENTS XVll CHAPTER XXXI\^~U.\n3ELi.iFKR^ (Carrot Family). Stems and Leaves — Inflorescence and Flowers — Fruit — Geographical — Key to Cenera of Economic Importance. .. .530-533 Daucus carota (Carrot) — Habit, Root and Stems — Leaves — Inflorescence and Flowers — Fruit and Seed — Geographical —Varieties — Uses 533~536 Pastinaca sativa (Parsnip) — Habit, Roots, and Stems — ^Leaves — Inflorescence and Flowers — Fruit and Seed — Geographical —Varieties 536-538 Apium (Celery and Parsley) — Generic Description — Geo- graphical — Key to Principal Species of Apium S38-539 Apium petroselinum (Parsley) — Description — Varieties 539-540 Apium graveolens (Celery and Celeriac) — Description — Geo- graphical — Types and Varieties — Uses 540-542 References 542 CHAPTER XXXV.— Vacciniace^ (Huckleberry Family). Habit — Leaves — Inflorescence and Flowers — Fruit 543^545 Vaccinium — Pollination — Fruit — Geographical — Key to Chief Fruit-bearing Species of Vaccinium S45~547 Gaylussacia (Huckleberry, Tangleberry, Dangleberry) — Description — Geographical — Kej^ to North American Species of Gaylussacia 547 Cranberries — Vaccinium macrocarpon — Types — \'accinium oxycoccus, Vaccinium vitis-idaea 548-550 Huckleberries and Blueberries 550 References 550 CHAPTER XXXVL— Oleace^ (Olive Famly). Family Description — Geographical, and Economic Impor- tance 551 Olea europoea (Olive) — Description — Seed Germination — Propagation— Uses 551-553 CHAPTER XXXVIL— Convolvulace^ (Morning Glory Family). Habit — ^Leaves— Inflorescence and Flowers — Fruit — Key to Important Genera 554^555 Ipomoea batatas (Sweet Potato) — Roots and Stems — Leaves — Inflorescence and Flowers— Geographical, and Environmental Relations — Closely Related Species — Types and Varieties — Leaf Shape as a Basis of Classification — Uses — References. .555-558 CHAPTER XXXVIIL— SoLAN.^CE^ (Potato Family). Habit of Plants — Leaves — Inflorescence and Flowers — Fruit — Key to Important Genera 559~56o Solanum — Habit — Leaves — Inflorescence, and Flowers — Fruit — Geographical — Key to Important Species of Solanum. .560-561 XVlll CONTENTS Solanum tuberosum (Potato) — ^Habit — Roots — Stems — Leaves — Flower — Opening of Flower and Pollination — Fruit — Seed — Germination — Development of the Seedling — Tubers from Seedlings — Tuberization — Fungus Theory of Tuberiza- tion — History — Varieties — Tuber Morphology^ — Periderm or Skin — Vascular Ring — P arenchym a — Cortex — ^MeduUa — Shape — Color — Eyes — Germination or Sprouting of Tuber — Physical Composition of Potatoes — Chemical Composition of Potatoes — Starch and Sugar — "Mealiness" — Quality of Potatoes — Degree of Maturity and Quality — Degeneracy of the Potato — Environmental Relations — Uses of Potatoes — Production of Potatoes 561-585 Solanum melongena (Eggplant, Guinea Squash) — Description ■ — Types and Varieties 585-587 Lycopersicon (Tomato) — Habit of Growth, and Stems — Roots — Leaves — Inflorescence and Flowers — Pollination, Fertiliza- tion, and Development of the Fruit — Parthenocarpy — Ab- normal Tomatoes — The Mature Fruit — Geographical — Im- portant Species and Varieties— Key to Types of Cultivated Tomatoes — Closely Related Forms — History — Uses 587-592 Capsicum annuum (Peppers) — Description — Geographical — Other Species — Types — Key to Botanical Varieties of Capsi- cum annuum — Composition — Uses 592-596 Nicotiana (Tobacco) — Habit — Leaves — Inflorescence and Flowers — Fruit — ^Geographical Distribution and Economic Importance 596-597 Nicotiana tabacum (Tobacco) — Habit, Roots, Stems — ^Leaves ■ — Inflorescence and Flowers — Pollination and Fertilization — Fruit — Geographical — Closely Related Species — Tjpes and Varieties — Composition — Curing Tobacco — The Tobacco In- dustry —References 597~6o5 CHAPTER XXXIX.— CucuRBiTACE^ (Gourd Family). Habit — Stems and Leaves — Flowers — Fruit — Germination of Cucurbit Seeds — Key to Principal Genera 606-610 Cucurbita (Squash, Pumpkin, Gourd; —Stems, Leaves, Flowers — Pollination and Fertilization — Mature Fruit — Geographical — Key to Important Species of Cururbita 610-612 Cucurbita pepo — Description^ — Origin — Types and Varieties. 613 Cucurbita maxima — -Description — Types and Varieties 614 Cucurbita moschata — Description — Types 615 Cucumis (Muskmelon, Cantaloupe, Cucumber) — Stems, Leaves, Flowers — Pollination — Geographical — Key to Prin- cipal Species 615-617 CONTENTS XIX Cucumis melo (Muskmelon, Cantaloupe, Melons) — Descrip- tion—Botanical Varieties of Cucumis melo 6i8-6jo Cucumis salivus (Cucumber) — Description — Geographical — — Closely Related Forms — Types — Pickles 620-622 Cucumis anf,'uria — Description 622 Citrullus (Watermelon, Citron, Colocynth) — Description — Geographical 622-623 Citrullus vulgaris (Watermelon, Citron)- — Description — Geo- graphical — Types and Varieties 622-624 References 624 CHAPTER XL.— Composite (Thistle Family). Habit — Leaves — Inflorescence — Flowers — Key to Important Genera 625-628 Lactuca sativa (Garden Lettuce)— Description — Origin, and Geographical — Types of Lettuce — Key to Types of Lettuce. . 629-633 Tragopogon porrifolius (Salsify or "Oyster Plant") — Descrip- tion — Geographical, and Closely Related Species — Uses 633-635 Cichorium (Chicory or Succory, and Endive) — Description — ■ Geographical 635 Cichorium intybus (Chicory or Succory) — Descfiption — Uses, and Varieties 636 Cichorium endiva (Endive) — Description — Geographical Distribution, and Economic Uses ' 636-638 Helianthus tuberosus (Jerusalem Artichoke) — Description — Geographical — Closely Related Species — Uses 639 References 639 Glossary _ 641-651 Index 6 ^ ^ BOTANY OF CROP PLANTS PART I CHAPTER I THE SEED PLANT BODY The seed plant body, like the human body, is made up of a number of separate parts or members. In the lowest plant group, the Thallophytes (thallus plants), including algae (pond scums, sea weeds, etc.), and fungi (molds, mildews, mushrooms, etc.), the plant body is relatively simple; it is not composed of distinct members, such as leaves, stems, roots and flowers. Such a simple, undifferentiated plant body is called a thallus. Between the typical thallus of algae and fungi on the one hand, and the highly complex and well- differentiated body of seed plants on the other, there are many intermediate forms, as for example, among the liver- worts (Hepaticae). Principal Parts of Seed Plant Body. — The parts of the plant body may be classified according to the work they do, into two groups: (i) those that carry on vegetative activity; and (2) those that carry on reproductive activity. In seed plants, the stems, leaves and roots are chiefly concerned with maintaining the life of the individual plant, that is, carrying, on the vegetative (nutritive) functions, such as absorption of materials from the soil, manufacture of foods, respiration, 2 BOTANY OF CROP PLANTS transpiration, etc., while the flowers which produce seeds, carry on, for the most part, the reproductive activities, and thus preserve the Hfe of the race. However, we know that many seed plants, such as potatoes, asparagus, cane fruits, strawberries, and others may be propagated by using vege- tative parts. of the plants. The above classification has a physiological basis. We may also divide the seed plant body into two systems on a structural basis, as follows: 1. Shoot system, including stems, leaves, flowers, fruit and seed. The stems may be in the air {aerial) or underground; the leaves may be ordinary foliage leaves, floral leaves (flower parts), or scale leaves. 2. Root system, which may be in the soil, the water or air. The roots, stems, leaves and flowers are not always typical, but may be modified or disguised, in some cases to such an extent as to be scarcely recognizable. For example, the tendril of the sweet pea is a leaf part, morphologically; the potato tuber, a modified stem; the sweet potato, a modified root. Size and Form of the Seed Plant Body. — There is a re- markable variety of forms and sizes of seed plants in the world. The duckweeds are very small, simple seed plants floating upon the surface of ponds. They are without leaves or with only very simple ones, they bear one or more rootlets, and extremely small flowers which usually consist of a single stamen or a single pistil. At the other extreme are the Giant Sequoias of CaHfornia; one individual, the General Sherman "big tree," measures 279.9 ^^^t in height and 102.8 feet about the base. . We commonly make a distinction between trees, shrubs and herbs — plants which differ much in form and habit. Trees and shrubs are woody, while herbs possess less woody tissue THE SEED PLANT BODY 3 and, consequently, are more soft and tender. The tree has a main trunk giving off branches at varying distances from the ground. The shrub may have a small main stem, but the shoots that arise at its base are equal to it in size. We note differences in the shapes of plants. Contrast the apple tree with its oval shape with the cone shape of the pine or spruce. Observe the general columnar form of the corn plant, and note how different it is from the broadly oval form of a vigorous alfalfa clump. Again, we see that while most plants are erect, a number, like the strawberry and melons, are prostrate on the ground. Others, like the grape, are climbing, and gain mechanical support from other objects. I CHAPTER II FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY Organs and Tissues.^ — We have said that the seed plant body is composed of a number of members: roots, stems, leaves, and flowers, bearing the fruit and seed. We may say that the plant body is composed of a number of organs, that is, well-defined parts that perform some definite function or functions. For example, those parts of the plant concerned with absorption we call absorptive organs, those that carry on reproduction, reproductive organs, and so on. The roots are the chief absorptive organs of all common seed plants, and the stamens and pistils of the flower the reproductive organs. Now, if we study microscopically the structure of organs, they are seen to be made up of one or more different groups of cells. Each distinct group of cells within the organ that has a common origin and a common role to perform, is desig- nated a tissue. For example, the pistil (a reproductive organ of a flower) is composed of several different tissues such as parenchyma tissue, conductive tissue, and epidermal tissue. Still deeper analysis of tissues shows all to be made up of small microscopic units — the cells. The Plant CeU. — Discovery of the Cell. — The discovery of the plant cell is attributed to Robert Hooke, an English lens manufacturer. In his microscopic study of thin sections of ordinary bottle cork, in 1667, he observed the cork tissue to be composed of very small compartments, very much alike in size and shape, and fitting closely together. It happens 4 FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 5 that the separate units making up the cork tissue resemble the cells of a honeycomb, and hence Hooke gave the name "cell" to the units of cork tissue. Although an inappropriate name, in that the majority of plant cells have no resemblance to those of a honeycomb, the name still chngs to botanical terminology. Hooke's discovery, although an epoch in the history of biology, was to be followed by others of far greater importance in that they tell us of the real nature of the cell, its marvelous inner structure, and most wonderful activities. The Cell as a Unit of Structure. — Just as a brick house is made up of individual units, the bricks, so is a plant composed of individual units, the cells. A plant is made up of cells and the products of cells, and nothing else. The wood, the root, the flower parts, the leaf, are made up of cells and cell prod- ucts. This must not be understood to mean that all parts of a plant are alive; but the non-living portions are products of the living material within the cell. The Cell as a Unit of Plant Activity. — The activities of a plant take place within the cells, for it is within them that we find the living material — protoplasm. Some of the sim- plest plants are unicellular, that is, one-celled. In such a case, the individual plant is simply one cell. That one cell, that individual, is capable of carrying on all the processes — absorption, respiration, digestion, assimilation, reproduction, etc.^ — upon which its hfe and the life of the race to which that plant belongs are dependent. Somewhat higher in the scale of plant life, we find some plants, algae, for example, composed of a number of cells, several hundred, for instance. In this case, the individual plant is multicellular, and yet, in this plant, each cell is a unit of activity, and each carries on its activities quite independently of the others to which it is united, as is evidenced by the abihty of the individual cells to live and reproduce when separated from its neighbors. In 6 BOTANY OF CROP PLANTS the higher seed plants, there are many different sorts of cells, both in structure and function, and the different cells are more dependent one upon another than are the cells that make up the simple algal filament. Yet, even in the seed plant, each cell is a unit of activity, and each is carrying on its functions more or less independently of its neighbors. The physiological unit of the plant is the cell. The Structure of the Plant Cell (Fig. i).— It must be understood at the beginning that plant cells vary a good deal in size and shape. However, the fundamental structure of all plant cells is much the same. The plant cell consists of a living mass {protoplast) of protoplasm enclosed in a non- hving cell wall. The wall is manufactured by the protoplast, and serves as a protection to it. If we examine the proto- plast, we see that it is composed of rather definite parts. There is an outer, thin, and transparent living membrane about the protoplast, which is only made manifest by treating the cell in a special manner. This membrane is known as the protoplasmic membrane, ectoplasm or hyaloplasm. It is all- important in the intake and outgo of substances. If a plant tissue is immersed in a sugar or salt solution which has a greater concentration than the cell sap, water is drawn from the protoplast of each cell through the protoplasmic mem- brane, and the protoplast shrinks, thus pulling the membrane away from the cell wall and making it visible microscopic- ally. Imbedded within the body of the protoplast there is a darker and denser mass of protoplasm, the nucleus, sur- rounded by its own living nuclear membrane. It may con- tain one to several small, darker bodies, the nucleoli. The protoplasm outside the nucleus is designated the cytoplasm. Hence we see that the protoplast is made up of three main parts: protoplasmic membrane, cytoplasm and nucleus. The protoplasm has spaces within it, which are filled with cell sap. FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 7 I These spaces are called vacuoles. However, one must not think of the cell-sap spaces in the protoplasm as vacuums, as the rather inappropriate name "vacuole" may suggest. Vacuoles are numerous and small in the young cells, but as Fig. I. — A, young cells from onion root tip; d, protoplasmic membrane; c, cytoplasm; a, nuclear membrane; d, nucleolus; e, plastids (black dots). B, older cells farther back from the root tip; /, vacuole; note that the cells have enlarged. C, epidermal cell of Tradescantia zebrina; in its natural condition of the right, and, on the left with the protoplast drawn from the cell wall as the result of immersing the cell in a solution the concentration of which is greater than that of the cell sap. This phenomenon is called plasmolysis. g, contains the plasmolyzing sokttion. (After Stevens.) the cell ages, they coalesce to form larger spaces. In some instances, there is one large central vacuole, while the cyto- plasm and nucleus are squeezed out close to the cell wall. 8 BOTANY OF CROP PLANTS All vacuoles are bordered by a protoplasmic membrane, simi- lar to the ectoplasm. Suspended within the cytoplasm are specialized living bodies, the plastids, also numerous granules, which may be of living material and insoluble food particles, such as starch or protein. The cytoplasm may hold insoluble crystals of salts, chiefly calcium oxalate. Let us arrange the parts of cell thus far described in outline form as follows: Plant cell Cell wall (non-living) I Protoplasmic membrane (living) I Nucleus (living), containing one or more nucleoli Protoplast. \ f plastids (living) ^ , granules (living or non-living) Cytoplasm. \ '' /■ .^. I crystals (non-livmg) [ vacuoles, containing cell sap. The Cell Wall. — The cell wall is a product of the proto- plast. When young it is almost pure cellulose. As the cell grows older, its wall may thicken and become denser, and have added to it certain substances such as lignin, su- berin, cutin and pectin which give it different physical and chemical qualities. Plastids. — These are specialized masses of protoplasm suspended within the cytoplasm. They vary in size and form. There are three sorts of plastids based upon their color: (i) leuco plastids, colorless; (2) chloro plastids, green; and (3) chromo plastids, yellow, orange or red. Nucleus. — All typical cells have a definite nucleus. It is wrong to regard the nucleus as the "seat of life" of the cell, for other portions of the cell are all-important, but it is a most essential part of the cell. If the nucleus is separated from the cytoplasm by artificial means, the cell dies. Its presence is needed, it seems, to stimulate respiratory activity. Moreover, reproduction of the cell — its division to form two FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 9 cells — involves definite nuclear changes, which has led to the opinion that hereditary characteristics are carried by nuclear matter. The structure of the nucleus is indeed complex, and there is a wonderful chain of changes that it goes through at the time of cell division. Protoplasm. — In 1840, Hugo von Mohl drew attention to the fact that the slimy substance in the plant cell was responsible for its life, and that as soon as it was removed, the cell no longer had the properties of livingness. The name protoplasm was applied to the living portion of the plant cell. Somewhat later, 1850, Ferdinand Cohn, gave positive evidence of the identity of the living material (protoplasm) in plant cells, and of the living material (so- called ''sarcode") in animal cells. If we examine a small bit of protoplasm under the micro- scope we see that it is a semi-transparent, jelly-like, rather granular substance, resembling very much the white of an egg. It feels slimy. Protoplasm is a very complex chemical substance. Al- though no element has ever been found in protoplasm that is not also found in the common substances in the world about us, the exact arrangement and proportions of these elements has not been ascertained, except in a general way. It is quite clearly estabHshed that protoplasm is a proteid, of complex nature, with water as a solvent. Proteids form about one-half or two-thirds of the dry substance of pro- toplasm. The remainder is fat, sugar, and other carbohy- drates, organic acids, organic bases, and some mineral substances. CHAPTER III ROOTS Development of Root Systems. — The root system of a plant is the entire collection of roots. Let us trace out the development of different root systems, starting with the seed. If we examine soaked grains of wheat, or bean seeds, or beet seeds, we observe that there is a young root already formed within the seed. Three germinating stages in wheat are shown in Fig. 2. The one principal root or primary root we see in the grain is the first to appear. It breaks through the root sheath (coleorhiza) which remains as a collar about the root where it breaks through the grain coat. Very soon two lateral roots appear; hence the primary root system or temporary root system consists of a whorl of three roots. Since these three roots were in the seed in the embryonic condition they are called seminal (seed) roots. The secondary roots appear in whorls at the joints on the stems some distance above the three temporary roots. The first whorl of permanent roots in wheat is generally about i inch below the soil surface, no matter at what depth the grain was planted (Fig. 3). One whorl of roots after another is formed above the first one, and as a result there is built up a fine network of roots, with their branches. A root system such as described in wheat is called a fibrous root system. We spoke above of the three seminal or seed roots, and the development of whorls of roots from the nodes above as shown in Fig. 3. Roots not arising from the seed or as ROOTS II branches of seed roots, but from stems or leaves, are called adventitious roots. Hence the fibrous root system of wheat, and of all the other cereals and grasses, is in reality composed of roots that develop adventitiously. Adventitious root leaj Fig. 2. — Three germinating stages in wheat. systems may appear under a variety of conditions. When young onion "sets" are placed in the ground, a set of roots (adventitious roots) appears at their bases. If young one- year-old twigs or stems (cuttings) of apple, raspberry, willow, geranium, carnation, chrysanthemum, rose, or of many other economic plants are placed in damp soil or sand, adventi- 12 BOTANY OF CROP PLANTS tious roots will appear at the cut surface, and by develop- ment, form the characteristic root system of the plant. Some Fig. 3. — In spite of the fact that the grain of wheat was planted at too great a depth, the permanent roots were formed at about i inch below the soil surface. leaves will even develop adventitious roots from cut or wounded leaf veins. This is true of such leaves as begonia. ROOTS 13 gloxinias, and bryophyllum. In the black-cap raspberry and in dewberries, a shoot (stem) may bend over by its own weight, and where it strikes the ground, develop adventi- tious roots, and thus secure a foothold. When once the tip has rooted well, the stem may be cut loose from the GROUND LINE ^ H •^ Fig. 4. — Tap-root system of young sugar beet. {Maxson.) parent stem and such rooted tips used as "sets." Straw- berries produce slender stems, called runners. Adventitious roots may be produced at the nodes. A very different sort of root system develops in such plants 14 BOTANY OF CROP PLANTS as the beet, radish, turnip, parsnip and carrot. In the germi- nation of the beet seed, for example, the primary root pushes out, takes a straight downward course, and gives off a few lateral roots. Hence, the primary root system of the beet consists of one main root extending downward, with a few fine laterals. Adventitious roots do not arise, as in wheat, nor does the primary root system die, as it does in wheat, but the main tap root of the young plant continues to elongate, and to give off lateral roots and rootlets (Fig. 4). The "beet" itself is for the most part an enlarged tap root. The tap root of the sugar beet may reach a depth of 4 feet, and often 6 or 7 feet. The upper laterals are the largest of the branch roots and extend farthest in the soil, spreading almost horizontally 2 to 3 feet. The lower laterals are more vertical and those near the very tip are almost parallel with the tap root. A root system such as possessed by the beet, radish, turnip, parsnip, carrot, dandelion, red clover, and many other plants is called a tap-root system. The Work of Roots. — ^A root system absorbs, anchors, and serves as storage organ. The small, young, tender roots, with their root hairs, are largely absorption roots, but as the plant gets older, new absorptive roots are continually being formed, while the older ones become thick and woody and serve mainly as anchorage organs. Familiar storage roots are those of the beet, carrot, turnip, parsnip, sweet potato, and dande- lion. The food material stored up by such plants for their own use furnishes a large proportion of the food supply of man. Irish potatoes (tubers) are not roots, but stems, and hence their discussion will be reserved for the proper section in the book. Effect of Environment upon Character of Root System. — It is noted, when roots make a vigorous growth, as they will under favorable soil conditions, that there is a very extensive ROOTS 15 system of rootlets developed. Corn is found to have a large part of its lateral root system in the surface layers when the soil is poor. The general form of a root system may be changed by transplanting. As a result of the necessary in- jury accompanying this process, there is developed a compact root system. Desert plants usually have an extensive root system, reaching to considerable depths. Swamp plants, even trees, develop a spreading, and comparatively shallow root system. The method and amount of watering affect the general shape of the endodermis /penblem - -'*-. /dermatogen root system. Fruit trees, for example, send their roots into the deeper soil layers if the surface layers are dry, but if the ground water level is close to the soil surface the root sys- tem will be more super- ficial. The character of the root system is often an index of soil conditions. General Characteristics of Roots. — It will be re- called that the seed plant body possesses a number of members, each with more or less distinctive characters. Roots have characteristics which stand out in quite marked contrast to those of other plant members. Roots do not give off their branches in a regular order, as stems do. They do not bear buds, except in very rare cases. Roots usually bear a root cap (Fig. 5) which pro- tects the growing point, while the growing point in stems reg/on of ^ iellmu/iiplicavotf Fig. 5. — Median lengthwise section of the apex of a root of barley. {After Sirasburger.) 1 6 BOTANY OF CROP PLANTS is either naked or surrounded by modified leaves (bud scales) . There are other characters which will be mentioned further on. Classification of Roots Based upon Their Medium of Growth. — The medium of growth of most roots is soil. Such roots may be called soil roots. It is customary for us to think of the root system of a plant as growing in the soil, just as we associate the shoot system with the air above ground. However, not all roots live in the soil, and not all shoots live in the air. There are water roots, and air roots, as well as the ordinary sort, soil roots. Water roots occur in such floating plants as the duckweeds, water hyacinth {Eichhornia speciosa). Water roots produce but a few branches. They possess no root hairs; absorption takes place through any cells on the surface. Air roots occur in many plants, such as corn (Fig. 56, B), Virginia creeper, tropical orchids, the banyan and other species of Ficus. Air roots are well shown in corn. In addition to the ordinary underground (soil) roots, corn develops aerial (air) roots, the so-called prop or hrace roots (Fig. 56, B). These arise at successive levels above the surface, extending obhquely downward. As aerial roots, they are unbranched, but they branch profusely when they strike the soil. They have the role of absorption, then, as well as anchorage. In the banyan, for example, the air roots are often very large, and arise from branches far above the ground. They grow downward, and when they strike the ground, become firmly attached, and act as a support or prop to the heavy branches. Hence, we learn that not all roots have soil as their medium of growth, but that air and water may be the media for some. Structure of Roots.^ — ^Let us cut a median (middle) length- wise section of a young root. It will appear as in Fig. 5. We shall see then that the root has a cap of loose cells at the ROOTS 17 tip. This protective structure is called the root cap. Just back of the root cap is the region of greatest cell multiplica- tion (Fig. 5), composed of cells that are actively growing. The very tip of the cap is continually sloughing off, while new cells are being added to it just in front of the growing point. In addition to the root cap we note that there are three distinct parts to the root, namely, (i) dermatogen, an outer layer or layers; (2) plerome (axis); and (3) periblem, between the dermatogen and plerome. The dermatogen becomes the epidermis, the plerome the stele or central cylinder, and the periblem the cortex. It is often possible to strip the cortex and epidermis from the central cylinder, which is composed of tough, fibrous tissue. The cortex (Fig. 6) is composed of large, thin-walled cells, which do not fit closely together, but leave air spaces (inter-cellular spaces) between. The innermost cortex layer is called the endo- dermis. The outer cortex cells may become prolonged to the side to form root hairs. The central cylinder or stele (Fig. 6) is bounded by a single layer of cells, the pericycle, which lies adjacent to the endodermis. Within the stele are found alternat- ing bundles or strands. The woody, water-conducting bun- FiG. 6. — Cross-section of a young root of Phaseolus mul- tiflorus. A, pr, cortex; m' pith; X, stele or central cylin- der — all tissue within the peri- cycle, inclusive; g, primary xylem bundles; b, primary phloem bundles. B, cross- section of older portion of root; lettered as in A; b', secondary phloem. (After Vines.) BOTANY OF CROP PLANTS ^' -br )"r dies are called the xykfn, the softer, food- conducting bundles, phloem. The central portion of the stele is composed of large, loosely fitting cells, making up the pith or medulla. Side roots arise from the outer edge of the stele (central cylinder), and push their way through the cortex and epidermis (Fig. 7). This method of origin of side branches is characteristic of roots. In stems the side branches arise from the outer part of the cortex (Fig. 15). Branch roots are said to have an endogenous origin, while branch shoots (except those in mono- cots) have an exogenous origin. As the root grows older, new xylem and phloem are formed, and by and by, it be- comes very tough and woody, serving as an efficient anchorage organ. Root Hairs — the Absorbing Organs of a Plant." — The great problem of all our com- mon plants is to take in as much water from the soil as they lose to the air, i.e., to main- tain a balance between water intake and water outgo. We speak of the roots as the absorbing organs of the plant. In a sense this is true, but it must be understood that water and soil solutions are not taken in at all points on the surface of the root system. Practically all absorbed substances enter Pig. 7. — Young root of white lupine showing origin of lateral roots from the stele. {After Gager.) ROOTS 1 9 the plant through root hairs, which are found near the tips of the smallest rootlets. In reaHty, the root hairs are the ab- sorbing organs of a plant. When we pull up any common herbaceous plant, we observe, as a rule, a large number of hair-like rootlets as branches of larger roots. These fine ''hair roots" are sometimes mistaken for root . hairs. But, closer examination, in which a hand lens may be necessary, shows us that these hair roots are the bearers of root hairs. In fact, root hairs are found only on the smallest and youngest rootlets. Root-hair Zone. — Root hairs do not grow along the full length of a rootlet, but occupy a definite zone, designated the root-hair zone. This is clearly seen in young seedhngs, grown on moist filter paper. The root- hair zone appears as a white fuzzy coating. The root cap is free of root hairs. The length of the zone varies from a few milli- meters to several centimeters. The root- hair zone of seedhngs grown in soil is plainly evident from the mass of soil particles held by the root hairs (Fig. 8). Each root hair f in its growth flattens out over, and some- ^^i^- S-— Wheat ° . . , seedling showing times partially surrounds, the soil particles soil particles cling- with which it comes into contact, thereby L'^^V^the roo^ forming a close connection with the water cap is free of root Hnirs and solutes that form a thin film around each soil particle (Fig. 9). Furthermore, the root hairs become mucilaginous, and this, along with their partial sur- rounding of particles, explains the presence of the mass of soil particles that cHngs to rootlets in the root-hair zone. Root hairs are short-lived, persisting for only a few days or 20 BOTANY OF CROP PLANTS weeks. New hairs are constantly formed anew at the an- terior end of the root-hair zone, while those at the posterior end are dying. Root hairs do not become roots. Structure of a Root Hair.^The root hair is a single cell. It is a simple, lateral prolongation of a border cell of the cor- tex (Fig. 9). It has the shape of a slender tube which may, however, become greatly contorted in its growth between and about soil particles. Root hairs vary in length from a frac- tion of a millimeter to 7 or 8 millimeters. The walls are thin Fig. 9. — Root hairs. (After Ga ger.) and of almost pure cehulose. A thin layer of protoplasm may Hne the walls, and the nucleus usually occupies a posi- tion near the apex. The central vacuole is large, and is filled with cell sap. The cell sap contains water, and various or- ganic and inorganic substances in solution. Effect of External Factors upon Development of Root Hairs.- — Most air and water roots have no root hairs. Soil roots, such as those of conifers, oaks, and others that are surrounded by a fungus (mycorrhizal growth) possess no root hairs. In the case of ordinary soil roots, root -hair develop- ment is usually meager in very wet soil. Corn roots develop root hairs in abundance in moist air, but none at all in water. The absence of root hairs in very wet soil, and in water, is probably to be attributed to poor oxygen supply. In a ROOTS 21 water-soaked soil, the air spaces are tilled with water. Our ordinary crop plants require a well-aired soil in order to de- velop root hairs in abundance. One of the chief objects of stirring the soil is to admit air to the roots. Orchard trees have been known to die as a result of the "puddling" of the soil. Trees are also sometimes killed by cattle tramping and packing the ground about them, such that the air supply to the roots is largely cut off. Root-hair development is often inhibited by a concentrated soil solution. High tempera- tures, and low temperatures, are inimical to root-hair growth. Root hairs develop in the light and dark about equally well, providing there is ample moisture. Length of Life of Roots. — Roots that live but one vegeta- tive period, that is, one season, are annual. All of our com- mon cereals, such as wheat, oats, barley, rye, corn, rice, sorghum, and also such common crop plants as buckwheat, beans, peas, tomatoes, melons, etc., have annual roots. Biennial plants live two vegetative periods. Common biennials are beet, cabbage, carrot, and parsnip. From the seed of beet, for example, there is developed the first season a large fleshy tap root, and a short crown from which the leaves arise. This fleshy structure ("beet"), stored with food, rests over the winter, and the next growing period sends up stout, branching stems to a height of 3 or 4 feet, w^hich give rise to flowers and seed (Fig. 119). At the end of the second season of growth, after seed production, the entire plant dies. Under our cultural conditions winter wheat is a biennial. The roots of trees and shrubs and some herbs live from year to year, increasing in size each season. Such plants are perennial in habit. In most cases the length of life of roots is the same as that of the shoot system. How- ever, underground perennial stems, such as are possessed 'v- quackgrass, Canada thistle, false Solomon's seal, etc., may have annual roots. CHAPTER IV STEMS Development of Shoot System.— When a grain of wheat germinates, the primary root is the first to appear. Very soon two lateral roots make their appearance, forming a primary root system of three roots. Also, the young stem (Fig. i) elongates, and there is formed the first shoot system of the plant. Elongation of the stem continues by growth at the tip, where the cells are young and active. It is observed that the stem is divided into sections (inter- nodes) ("Fig. 25). The nodes, the enlarged joints between the internodes, give rise to leaves, and if we follow the wheat plant through its Hfe, we observe that the stem terminates in an inflorescence (flower cluster). Now, in addition to the one main stem that arises as a prolongation of the embryonic stem in the seed, branches arise from the lower nodes. These branches arise in the axils of the lowermost leaves, in most cereals. In cereals, this branching is known as "stooling" or ^'tillering.'' Common cereals invariably produce a num- ber of tillers or branches from the primary stem, and these in turn other tillers (lateral branches) , so that under favorable conditions several dozen culms may result from a single seed. In the wheat plant, two or three weeks old, three or four buds (young stems) may be found, one in the axil of each leaf. Tillering results from the outgrowth of these lateral buds. Hence, as a result of the elongation of the main growing point, and of the lateral growing points into lateral STEMS 23 branches of the primary stem, there is built up a shoot sys- tem, with its leaves and flowers. Buds. — A bud is an undeveloped stem; it is simply a young shoo<. In an ordinary shoot, an apple or peach twig for example, the internodes are considerably elongated. In rapidly growing water sprouts, internodes may be several inches in length. A bud is a very short, young shoot in which the internodes 'are few or are exceedingly short. That a bud is a young, individual shoot in itself is shown by the fact that buds may be removed from a branch and applied to the surface of the growing tissue (cambium) of another branch (stock) and successfully grown there. In fact, bud grafting is a common horticultural practice. The tip of the bud is usually protected by a series of overlapping scales (bud scales), which are in reaHty modified leaves. Naked buds are not protected by scales; they are found on woody plants of the moist tropics, and are the only sort on herbaceous plants the world over. Classification of Buds.— Buds may be classified as to development into: (a) leaf, (b) flower, and (c) mixed buds. If we open up a leaf bud, we find a very much shortened axis or stem bearing a number of small leaves. As the leaf bud is a young shoot, it may as properly be called a branch bud. That is, it elongates into a branch which bears leaves. The new shoot, just as the old one from which it came, ends in a bud, and in the leaf axils other buds arise. If we open up a flower bud, we find one or more young flowers. In plums, for example, the number of flowers in a bud varies from one to five, two and three being the most common numbers (Fig. 166). Mixed buds contain both flowers and leaves. The terminal buds at the ends of the short "spurs" in the apple are mixed buds (Fig. 153). It is not always possible to distinguish leaf from flower 24 BOTANY OF CROP PLANTS buds by their external appearance. In some cases, however, they have a different shape. In the apple, for example, fruit buds (here, really mixed buds) are rather thick and rounded, while leaf buds are smaller and more pointed. In all plums, the flower buds are lateral, and usually stand out at an angle of about 30°, while leaf buds are more ap- pressed to the stem. Buds may be classified as to their position on the stem into: {a) terminal, (b) lateral or axillary, {c) accessory or super- numerary, (d) adventitious , and (e) dormant. Most stems end in a bud. Such a terminal bud is almost always a leaf bud; occasionally it bears flowers, too, as in the apple. The terminal bud is normally the most vigorous of all on the stem, as is evidenced by the fact that it elongates into a shoot which exceeds in length those from the lateral buds. Lateral (side) buds arise in the leaf axils. They give rise to side branches or to flowers. Accessory or supernumer- ary buds are extra ones coming out in the leaf axils. They are best shown in the maples and box elder. Adventitious buds arise out of order, in unusual places, not in leaf axils or at the end of a stem. They are usually stimu- lated by injury. For example, when a branch is cut back, numerous adventitious buds develop about the edge of the cut surface. Dormant buds are ones that have arisen in a regular fashion in the leaf axil, but which, for some reason, do not develop. Hence, they may be grown over with the succeeding layers of wood and lie buried within the tissue in a latent condition. Such a bud may be called into activity later in the life of the plant and come to the surface. It would appear to be endogenous in its origin, while in reality it is exogenous. Irregular branching may result from the development of dormant buds, or as is more commonly the case, from the development of adventitious buds. STEMS Buds may be classified as to their arrangement on the stem into: (a) alternate, (b) opposite and (c) whorled. It is well to keep in mind that bud arrangement is the same as leaf arrange- ment, for the reason that buds normally develop in each leaf axil. Further- more, as leaf buds develop into shoots, the method of branching, and hence the form of the plant, is largely determined by the bud arrangement. When one bud occurs at each node, they are said to be alternate (Fig. lo). When two buds stand at a node, they are opposite (Fig. 103). When more than two buds stand at a node they are said to be whorled. Bud Variation. — This is a more or less common oc- currence in trees of all varieties. The buds on an apple, peach, or citrus tree, for example, differ from each other in important respects. That this differ- tetminal leaf -bud flower- buds \sHpule-scar leaf- scars'- - . . . tficels ■lateral leaf-buds latent bud- -terminal bud- scar .. flower- bud-scars old branch Fig. 10. — Cottonwood twig two years old. {After Longyear.) 26 BOTANY OF CROP PLANTS ence really exists can be well shown by removing branches or buds and growing them into independent plants. If we do this we will find that the individuals from the separate buds may vary in such respects as habit of growth, manner of branching, nature of foHage, form, color, texture and yield of fruits. Nearly all our fruits are multiplied by bud propagation (asexual parts) and not by seed (sexual parts) ; and many of the varieties of fruits now in cultivation are in reality bud varieties or " sports." A certain branch on a tree is observed to differ from the rest in some marked respect; and this branch is taken off and propagated as a new variety. General Characteristics of Stems. — ^Let us now examine a winter twig of the cottonwood, for example, that is several years old, such as pictured in Fig. lo. At the tip is a large terminal bud. If it is broken open, young overlapping leaves are found within. It develops into a leafy branch. The growth in length of the shoot results from the lengthening of the internodes in the bud. Along the side of the stem are lateral buds at regular intervals. These may be leaf buds or flower buds, as can be positively determined by breaking them open. Below each bud there is a half-moon-shaped leaf scar. Hence we see that leaf arrangement is also bud ar- rangement. By examining the leaf scar with a hand lens one sees several small bundle scars on the surface. Bundle scars are left by the vascular bundles that pass from the woody stem into the petiole (stem) of the leaf. Inflorescence scars are large circular or oval scars left by the falHng off of flower clusters. A leaf scar is observed beneath each inflorescence scar. The twig growth of each year is clearly distinguished by a ring of scars. When the closely arranged bud scales of a terminal bud fall off in the spring they leave a number of scars so close together as to make a ring. Hence STEMS 27 the limits of two successive years' growth are marked by bud scale scars of terminal buds. In this way we may determine the age of a twig. Close observation of the twig will reveal a number of whitish spots on the bark. These are lenticels (Fig. 11), structures on the stem composed of a mass of loosely fitting cells which permit the diffusion of gases inward and outward. Except for the lenticels, the bark prevents the free passage of air, and also the loss of water from underlying stem parts. '^e^om mt^^ Fig. II. — Section of the lenticel of elder. (After Sirasburger.) From A Te.xt-book of Botany by Coulter, Barnes, and Cowles. Copyright, by the American Book Company, Publishers. How Does a Stem Grow in Length? — A bud is a young shoot. A lengthwise section of a leaf bud shows a cone- shaped growing point (young stem) upon which is a number of young leaves. These leaves come off at regular intervals, following identically the same arrangement as they do in the adult twig. The growing point, then, consists of a number of very much shortened internodes. Growth in length of the shoot consists in the elongation of these in- 28 BOTANY OF CROP PLANTS ternodes by increase in number and size of cells that com- pose internode tissue. As a rule, the number of leaves that will be on a twig is already fixed in the bud. Seldom do new leaves originate during the growing season. This point is worthy of special mention: When a twig has made its year's growth, the internodes do not lengthen thereafter during subsequent years. Increase in length of that shoot is due to the addi- tion of other "joints" at the end. The fixed length of old internodes is well proven by the common observation that nails driven into the trunk of a tree, or a small branch, are not elevated above the ground as the tree grows. It will become grown over with wood, but its height above the ground remains the same. A common impression prevails that the branches of a young tree should be started low to the ground, so that they will be at about the right elevation above the ground when the tree reaches maturity. The sup- position here is that the limbs are raised by the growth of the tree. This notion is erroneous. Classification of Stems Based upon Their Medium of Growth. — The medium of growth of most stems is air. Such stems may arise from the soil as in nearly all of our ordinary plants, or they may have no attachment with the soil at all, receiving mechanical support from other plants. The latter are called epiphytes. Tillandsia usneoides is probably the best epiphyte among seed plants. It is the so-called "Spanish moss." Many orchids of the moist tropics are epiphytic. The entire shoot system of some plants is underground. This is the case in the ferns. Many plants produce both aerial and subterranean stems. For example, Canada thistle has horizontal underground stems, and from these are sent up aerial shoots bearing foliage leaves and flowers. Both STEMS 29 underground and aerial stems are possessed by sueh common plants as Irish potato, onion and asparagus. Water is also a medium of growth of stems, as is the case with such plants as Elodea, Potamogeton, water lilies, etc. "Modified" Stems.^ — Undoubtedly, the ordinary cylin- drical twig such as is found in trees and shrubs is the most common sort of stem. It is quite likely that we think of a stem as a plant part growing more or less erect, in fact, most stems do tend to grow erect. However, all stems are not as just described. As we take a survey of the plant kingdom, we discover many different forms of stems — stems that are so different from the ordinary sorts that they are scarcely recognizable as stems, and are identified, as such, only by careful study of their origin and structure. Among such stems are the following: I. Rootstocks or Rhizomes (Fig. 12). — These are under- ground, horizontally elongated stems. The rootstocks or rhizomes of Canada thistle are excellent examples. They bear reduced, scale leaves at the nodes. Lateral buds arise in the axils of these leaves, just as described in the cotton- wood twig — a typical stem. They grow in length from a terminal bud, which is unprotected by tough scales. Adven- titious roots are produced at the nodes. Rootstocks are efficient organs in the spreading of a plant. Here is a method of reproduction other than by seeds. Usually, aerial stems from the lateral buds of the rootstock are pro- duced; they may die back to the ground each fall. The plant lives over the winter by means of the rootstocks. Hence, rootstocks or rhizome-bearing plants are perennial. Many of our worst weeds are perennials from a rootstock. We may prevent such plants from going to seed, but in spite of this, and the cutting back of the leafy shoots, new shoots are sent up from the rootstocks. Furthermore, if the root- 30 BOTANY OF CROP PLANTS stocks are broken into a number of separate pieces by cultivating implements, each piece may develop adven- titious roots, establish itself, and send up leafy shoots. Fre- quent cultivation that has as its aim the destruction of new Fig. 12. — Portion of a sprouting potato tuber. shoots as soon as they appear, may succeed in starving out the rootstock after a time. The period of time depends upon the amount of stored food material in the structure. This method of eradication is based upon the knowledge that the STEMS 31 food of the plant is manufactured in the chlorophyll-bear- ing (green) cells above ground. 2. Tubers. — These are fleshy, underground stems. The best example is common Irish potato. Although the potato, ordinarily, would not be considered a stem, still if we follow through its development, and examine its structure, we are convinced that it is stem (Fig. 12). When we plant a slice of a potato, "sprouts" are soon sent out from the "eyes." These sprouts, with their nodes, and internodes, and their scale leaves, are quite obviously horizontal under- ground stems (rhizomes). Soon, the tip of a rhizome begins to en- large, and a potato is formed; hence, the potato is seen to be a simple enlargement of the tip of an underground stem. Furthermore, examination of the tuber reveals the presence of a terminal bud ("seed end" of the potato), and lateral buds along the sides. The buds are the so-called "eyes." In an elongated potato, we may be able to detect the spiral ar- rangement of the buds. Lenticels may also be observed on the corky layer (skin) of the bark of the potato. A section of a tuber reveals a stem structure. The three principal parts of an ordinary stem are bark, wood and pith. This is shown in a cross-section of an ordinary twig (Fig. 13). In the potato, these three distinct zones are visible, as indi- cated in Fig. 236. Hence, we see that the potato is in reaHty a modified stem. Fig. 13. — Section of stem showing a shedding leaf; also bark, wood and pith as seen in cross and longitudinal sec- tions. {After Longyear.) z^ BOTANY OF CROP PLANTS swollen le<^\ mses 3. Bulbs. — A bulb is an underground stem. The common onion is a typical example. A median, lengthwise section (Fig. 14) of the onion bulb, shows a small, cone-shaped stem upon which are numerous, fleshy leaves that are over- lapping and quite rich in food material. Here, too, there is a terminal bud, and lateral buds occasionally in the leaf axils. Bulbs are vertical stems, thus differing from the horizontal direction of growth of rhizomes. 4. Corms. — A coim is a short, solid, vertical, under- ground stem. It is typically exemplified in gladiolus. Corms are usually flattened from top to bottom, and bear a cluster of thick fibrous roots at the lower side, and a tuft of leaves on the upper side. Corms are storage organs. 5. Runners (stolons). — These resemble rhizomes in that their direction of growth is horizontal. In the straw- berry plant, the branches that arise from the axils of the closely set leaves are called "runners." They are slender stems, growing along the ground surface; they have long internodes, and produce leaves, flowers and roots at the nodes. Runners are used as a means of propagating the stem Fig. 14. — Median lengthwise section of common onion bulb. STEMS 33 strawberry plant. They arc attached to the old plant for but one season. Runners may branch. 6. Lianas. — A liana is a climbing stem, gaining mechanical support only from another plant. Common lianas arc the grape, Virginia creeper, hop, Japan ivy {Psedra tricuspidata) and morning glory. The stems of Hanas are slender, long, and have insufficient strengthening tissue to hold them perfectly erect. Hop stems always wind about the support clockwise (Fig. 102). Such a twiner is destrorse. The twin- ing stem of Virginia creeper bears fleshy, yellowish air roots which may aid the plant in adhering to its support. Of greater value to the Virginia creeper plant, in this regard, however, are the highly specialized branches — tendrils. In this case, a tendril ends in a knob which flattens out, when it comes into contact with a surface, and adheres to that surface by a mucilaginous disk-shaped structure. 7. Spines. — Some spines are reduced stem structures, as is the case in the honey-locust, hawthorn, wild crab, etc. Many small spines, such as are found in gooseberries, cacti, and roses, for example, are outgrowths of the stem. It seems that spines are induced by an excessive loss of water from the plant, and a low absorption rate, such as occur under desert and semi-desert conditions. STRUCTURE OF STEMS The Young Dicot Stem. — ^Let us cut a middle lengthwise section of a young dicot stem (Fig. 15). This section will cut the growing point (bud) of the stem, and the older parts back of the growing point. We see that the stem becomes progressively older farther and farther back from the tip. The cells at the growing point make up a tissue known as meristem tissue (undififerentiated tissue). Although they 3 34 BOTANY OF CROP PLANTS are similar in appearance, it is quite evident that they are capable of developing into different tissues. Just back of •lylem from the prooambi Xylem from the cambium Phloem, from the procainbluni and camtlulSi' Xylem from the procamblun Xylem from the cambium Phloem from the prooasblum and camblu'a Fig. 15. — Diagram showing the evolution of tissues from the primordial meristem down to the beginning of cambial activity. {After Stevens.) the growing point, we note that the cells have differentiated into three main regions: epidermis, ground meristem, and STEMS 35 procamhium strands. These three regions are best shown in a cross-section (Fig. 15). In a little older portion of the stem, such as shown in a section further back (Fig. 15), further differentiation has taken place, which changes involve the ground meristem and the procambium. The vascular bundle is composed of three re- gions: phloem, cambium and xylem. The center of the stem is made up of large, loosely fitting cells which constitute the pith or medulla. Radiating from the medulla out between the vascular bundles are a number of cells which make up the medullary ray. Dicot Vascular Bundle. — De- tailed examination of a dicot vas- cular bundle in cross- and longitu- dinal sections shows each of its three parts to be made up of characteristic structural elements. Phloem.— In the phloem are sieve tubes, companion cells, and phloem parenchyma. Each sieve tube is a single cell, much elon- gated and modified for conduc- tion. The end walls of sieve tubes (Fig. 16) are thickened, and per- forated by a great number of holes, and thus resemble a sieve. Each sieve tube is adjoined by a single row of small cells, the companion cells, which run parallel to it. Phloem parenchyma ceUs are somewhat Fig. 16. — Vascular elements- A, annular tracheal tube; B, spiral tracheal tube; C, reticu- lated tracheal tube; D, pitted tracheal tube; E, cross-section through plate of sieve tube, and adjoining companion cell; F, lengthwise section of sieve tube; G, portions of two com- panion cells. (E, F, and G after Strasburger.) 36 BOTANY OF CROP PLANTS vertically elongated, but they do not reach any consider- able size. Functions of Phloem Elements. — The functions of these three elements of the phloem are as follows: 1. Sieve Tubes. — Conduction of soluble carbohydrates, amido-acids and proteins. 2. Companion Cells. — Although sieve tubes lose their nuclei before the end of the first year, they do not die; hence, it is thought that companion cells extend their influence to the sieve tubes, enabling them to carry on the life processes for which a nucleus seems necessary. 3. Phloem Parenchyma. — The cells of this region store food material or conduct it short distances in the stem. Cambium. — The cambium layer is composed of one or more rows of small cells, flattened in planes that run at right angles to a radius of the stem. They are thin-walled cells, rich in protoplasm, and capable of rapid cell division and growth. The cambium is in fact the growing layer of the stem. In grafting, one stem, the scion, is inserted into another stem, the stock, in such a way as to bring the two cambium layers together. The cells of these layers possess the power of growth, and after a time there is a union. Xylem (Wood). — The chief structural elements of the xylem or wood portion of the vascular bundle are: tracheal tubes, tracheids, wood fibers and wood parenchyma. The tracheal or water tubes are long, large, tubes with thick walls. They have been formed by the elongation and en- largement of rows of cells, the common end walls of which have totally or partially dissolved, leaving a duct of consider- able length. The walls of the tracheal tubes become thick- ened, and the thickening material {lignin) is laid down on the inside of the walls in various patterns. STEMS 37 Kinds of Tracheal Tubes (Fig. i6).— There are the fol- lowing sorts of tracheal tubes: 1. Annular Tracheal Tubes.—Uere and there in the tube are thickened rings of Hgnin, which have the appearance of barrel hoops. 2. Spiral Tracheal Tubes.— The thickening material is in the form of a loose spiral. 3. Reticulated Tracheal Tubes. — In these, the strengthening material is laid down in such a fashion as to form a network on the wall. 4. Dotted or Pitted Tracheal Tubes.— In these, hgnin has been deposited over the inner wall in such a manner as to leave numerous circular thin places, which give the tube a dotted or pitted appearance. Tracheids (Fig. 17) are single cells, elongated and modified. They have thick, lignified walls with numerous bordered pits. In shape tracheids are Hke a spindle, and they fit closely together making up a strong supporting tissue. Tracheids, Wood parenchyma cells are usually thin- walled ''^j.*J^^°[^ and with unbordered pits. Wood fibers are long, taper-pointed at the ends and thick- walled. The pits are unbordered. Functions of Wood Elements. — The functions of the dif- ferent wood (xylem) elements are as follows: 1. Tracheal Tubes. — (a) Carry water and Solutes from the soil to and throughout the leaves; {b) give strength to the stem. 2. Tracheids.— (a) Carry water and solutes; (6) give strength to the stem. 3. Wood Parenchyma. — (a) Store water and foods; (b) and also conduct them short distances. 3? BOTANY OF CROP PLANTS 4. Wood Fibers.— Give strength to the stem. Growth in Thickness of Dicot Stem. — Medullary ray cells give rise to cambium that joins with the cambium in the vascular bundles.. Thus there is formed a continuous cam- bium ring (Fig. 15). At the end of the first year of growth or the beginning of the second, another sort of cambium, called cork cambium, is differentiated in the outer cortex. Growth in thickness of the stem consists then in the produc- tion and growth of new cells from: (i) cambium of vascular ring, and (2) cork cambium. The cambium cells of the vascular ring may differentiate into xylem, or phloem, or remain cambium. Each cambium cell divides by a wall which is parallel with a tangent to the outside of the stem. If the inner cell resulting from the division becomes a xylem element, the outer usually remains cambium. On the other hand, if the outer cell resulting from the division becomes a phloem element, the inner remains cambium. Hence, by a division of cambium cells of the vascular ring, new xylem is laid'down on the outside of the old xylem, and new phloem is laid down on the inside of the old phloem. Not only do the vascular bundles grow in a radial direction, but also somewhat laterally. This lateral growth of existing vascular bundles, together with the formation of new ones between the old ones, brings about a narrowing of the medullary rays, so that in an old stem they appear as mere Hnes or rays radiat- ing from the pith or medulla. And, furthermore, the wood comes to form quite a solid ring, as does also the phloem. In addition to the increase in stem thickness by the pro- duction of more xylem and phloem, the cork cambium cells aid in this process. Cork cambium cells which divide by a wall that is parallel to a tangent of the stem, give rise to cork tissue, and to secondary cortex. Hence, each year, there are produced in the dicot stem: STEMS 39 1. Wood, on outside of old wood. 2. Phloem, on inside of old phloem. 3. Cork, on inside of old cork. 4. Secondary cortex, on outside of old cortex. A two-year old woody dicot stem has the following general structure : 1. Bark, consisting of the following parts in order from outside to inside: Cork, cork cambium, secondary cortex, primary cortex, primary ^ phloem, secondary phloem. 2. Cambium of vascular bundle. 3. Wood, consisting of two layers, the youngest toward the outside. 4. Pith. 5. Medullary rays, each ray of several rows of thin-walled cells running from the medulla to the outer edge of the phloem. Monocot Stems. — The corn stalk is an excellent type of a monocot stem. In this, as shown in cross-section of the stem in Fig. 18, the vascular bundles (fibers) are scattered throughout the ground tissue. They do not form a definite "vascular ring" as in dicot stems. Moreover, the vascular bundles of most monocots do not possess cambium, as in dicot stems. Hence, new phloem and xylem are not produced each season, and consequently there are no annual rings formed. Growth of monocot stems results from (i) simple enlargement of cells derived from primary meristem tissue, and in some instances Fig. 18. — Cross-section of cornstalk stem; a, epidermis; h, cortex and peri- cycle; c, ground tissue. {After Stevens.) 40 BOTANY OF CROP PLANTS from (2) the formation de novo of vascular bundles from cells that have retained their meristematic power. Annual Rings. — An annual ring, as generally understood, is one year's growth of wood (xylem). The ring varies in width, depending upon the time in the life of the plant it was formed, and upon seasonal climatic conditions. Further- more, it is known that some trees grow rapidly, producing wide annual rings, while it is a specific character of others to grow slowly, i.e., produce narrow annual rings. There is usually a marked difference in the wood formed in the spring and early summer, and that produced in late summer and fall. In early or so-called "summer wood," tracheal tubes are large and quite numerous; in late or "autumn wood," tracheal tubes are smaller and fewer, and tracheids and wood fibers are relatively more abundant. Hence, "autumn wood" has more strength than summer wood. It is readily seen that the autumn wood of one year (say 1916) is adjacent to the spring wood of the following year (19 17). "Soft wood" is usually one which grows rapidly, and is dijfuse porous, that is, tracheal tubes are rather small and uniform in size and evenly distributed throughout the year's growth. "Hard wood" is usually a comparatively slow-growing wood, and is ring porous, that is, the tracheal tubes of the spring and early summer are large and numerous, while the autumn wood is solid as a consequence of the relatively greater abundance of tracheids and wood fibers. Bark. — The term "bark" with us includes all that portion of the stem down to the cambium layer. When the bark of a tree is peeled off, there are removed the following layers in order from outside to inside: cork, cork cambium, cortex, phloem, and portions of cambium. The cleavage line is the cambium zone. STEMS 41 The Work of Stems. — (i) The stems of trees, shrubs and common herbs are mainly concerned in the conduction of water and solutes from the soil, and of food materials. The need for a conductive system first arose in the plant kingdom when the food-making organs of the plant became elevated above the soil or water surface. (2) The stem also is a support to the other organs of the plant, and it brings into display the leaves, and flowers. The leaves are brought into a position where they may receive the light to advantage, and flowers are placed where their pollen may be disseminated by wind or bees, and seeds may be more easily spread. (3) In addition to conduction and support, stems may store food material, water and various waste products. In our woody perennials, such as the apple or peach, for example, an abundance of food material is stored during the winter in the medullary ray cells, also, in wood parenchyma, and in that portion of the pith adjacent to wood, and sometimes in all of the pith cells; portions of the phloem and cortex may also store food. The stems of such plants as the giant cactus, and other cacti, store large quantities of water. Some stems, such as the potato tuber, bulb, corm and root- stock, are heavily loaded with stored food material. (4) Young stems that contain chlorophyll in their outer layers possess the power of manufacturing carbohydrates, just as do green leaves. CHAPTER V LEAVES Development of Leaves. — Leaves appear at the growing point of a stem, as lateral protuberances (Fig. 15) consist- ing at first of a shapeless mass of cells. We call this group of cells the primordial leaf. By further cell division and dif- ferentiation (becoming different from each other) of these few cells the adult leaf arises. In the embryos of seeds the first few leaves are already formed, and even in this early stage may bear some resemblance in shape to the adult leaves. Parts of Leaf. — Most leaves have two distinct parts: hlade and petiole (leaf stalk) . Some leaves, as those of peas and beans, have two small, leaf-like structures at the base of the petiole. These are stipules (Fig. 19). The petiole is sometimes absent, the blade being mounted directly on the stem. Such a leaf is said to be sessile. Vascular bundles run from the stem out through the petiole into the blade, where they branch to form the network of veins. The veins not only carry water, solutes and food materials, but also form a framework for the softer tissue of the leaf. Kinds of Leaves. — It is possible to classify leaves in many different ways. Common green leaves that we are all familiar with are usually called foliage leaves. They are the chief food-making organs of all ordinary plants. However, there are many leaves that do not possess green coloring matter (chlorophyll) and hence, have no food-making power. 42 LEAVES 43 As examples of the latter, may be mentioned the small, scale leaves on underground stems, the scales enwrapping the growing point in buds, the bracts in grass inflorescences, and the petals, stamens and car- pels of flowers. We look upon ordinary foliage leaves as the most common, and hence "normal," sorts of leaves. We would regard scale leaves, bracts, bud scales, and flower parts as ''modified" leaves. Leaves may function as (i) food-making organs (foliage leaves), (2) protective structures (scales), (3) reproductive organs (floral organs), and (4) as storage organs. The fleshy leaves that make up the bulb of onion are good examples of leaves used for storage. Foliage leaves are either par- allel-veined or netted-veined. In leaves with parallel venation, there are many veins, about equal in size, running parallel, and joined by inconspicuous veinlets. This type of venation is characteristic of the leaves of grasses, sedges, rushes, lihes and most all other monocotyledonous plants. In leaves with netted venation, which is so well illustrated in leaves of apple, oak, maple, potato, cabbage and other dicotyledonous plants, there are a few Fig. 19. — A single compound leaf of sweet pea. 44 BOTANY OF CROP PLANTS prominent veins from which arise numerous minor veins, thus forming quite a conspicuous network. Leaves are often classed as simple or compound. The apple leaf is an example of a simple leaf (Fig. 159). In this there is an undivided blade. The bean, pea, carrot or parsnip leaf is compound (Fig. 19). The blade is divided into a number of segments, or leaflets. We may classify leaves as to their arrangement on the stem. Leaf arrangement is the same as bud arrangement, for ordinarily a bud arises in the axil of each leaf. They may be alternate, opposite or whorled (see page 25). Leaves vary widely in size, shape, character of margin, and base, texture, thickness, nature of epidermal coverings, etc. Some of these variations will be mentioned throughout the pages that follow. Structure of Leaves. — The structure of a leaf is best shown in a cross-section (Fig. 20). The upper epidermis, usually consists of a single row of cells. Below it, is the palisade layer, composed of one or more rows of cells the long axes of which are perpendicular to the leaf surface. Below the palisade cells is the spongy parenchyma, varying in thick- ness, and composed of rather irregularly shaped cells that lit together loosely, thus leaving intercellular spaces (air spaces) . The lower epidermis is seldom more than one layer of cells thick. Chloroplastids are abundant in palisade and spongy parenchyma cells, but absent from all epidermal cells except the guard cells of stomata. The outer wall of epidermal cells is normally thicker than radial or inner walls. Cutin, a fatty substance, highly im- pervious to water, is deposited on the outer wall, to form a layer called the cuticle. A thick cuticle is a common char- acteristic of leaves growing in arid situations. The same variety will develop a thicker cuticle under arid conditions LEAVES 45 than^when growing where there is ample water. A thick cuticle is a good drought-resistant character. The epidermal cells do not form a continuous layer over the two leaf surfaces. There are numerous pores or open- ings, the stomata (singular stoma, a mouth) (Fig. 20). Each stoma is bounded by two modified epidermal cells, differing Fig. 20. — Diagram showing the structure of a representative leaf. {After Stevens.) from ordinary epidermal cells in form, in their ability to change shape, and in the possession of chloroplastids. These are the guard cells. Leaves possess many different kinds of surface pecuHarities, such as hairs, scales, wax and resin deposits. These are features which tend to retard water loss from the leaf surface. There is the widest variation in leaf structure. That 46 BOTANY OF CROP PLANTS described above is typical of dicot leaves growing in situa- tions with a moderate water supply. Water leaves are thin and have no palisade tissue. PaHsade tissue is also absent in the leaves of grasses. The leaves of plants grow- ing in arid situations are usually thick. The increased thickness is commonly due to an increase in the number of rows of palisade cells. Palisade may develop on both upper and lower surfaces. Some leaves have palisade tissue from epidermis to epidermis. The thickness of leaves growing in arid conditions may also be, in part, the result of the de- velopment of a very thick cuticle. The Work of Foliage Leaves.— Leaves are very important organs of the plant. We are all familiar with the iiijury to a plant that results from defoliation through any cause, or from disease of leaves, or frohi their meager development. We have learned to associate an abundance of bright green leaves with plant vigor, just as we associate a rosy com- plexion with health in people. And, with but few excep- tions, we may judge of the health of a plant by its leaf development and color. Carbohydrates are made by green plants only, and only by those cells of green plants that possess chlorophyll. The cells of roots and other underground plant parts, and all those cells of the plant so far removed from the surface as to be beyond the influence of light, do not have chlorophyll, and hence, have no power of making carbohydrates. Other than that in the relatively small amount of green tissue in young stems and in the sepals of flowers, all the carbohydrate of the plant is made in the chlorophyll-bearing cells of leaves. The manufacture of carbohydrate by green tissue is called carbohydrate synthesis or photosynthesis. When we realize that carbohydrates form the basis of all the other more com- plex foods of the plant body, such as fats, amides and LEAVES 47 proteins, we see the great importance of a healthy leaf development. In addition to their important work of carbohydrate synthesis, the synthesis of the fats, amides and proteins is carried on to a large extent in leaf cells. We may truly say, then, that leaves are the food-making organs of a plant. Leaves are also the chief transpiring (water-losing) organs of the plant. Practically all of the water that escapes from a plant passes out through the leaves, chiefly through the stomata. When in a healthy growing condition, there is a continuous stream (transpiration stream) of water from the roots to the leaves. The leaves of many succulent plants, such as Agave, Russian thistle, salt wort, stone crop, and others serve as storage places for water. Agave leaves may also store food. The onion bulb is made up of a very short stem bear- ing numerous, overlapping, fleshy leaves in which consider- able quantities of food are stored. The leaves of the sundew {Drosera), and pitcher plants {Sarracenia and Nepenthes) are highly modified as special organs that catch, digest and absorb insects. CHAPTER VI FLOWERS Parts of Representative Flower. — A representative flower such as shown in Fig. 21 has the following parts taken in order from the outside to the inside: 1. Calyx, made up of sepals, which are green, and enclose the other flower parts in the bud. 2. Corolla, made up of petals, which are usually the colored portions of the flower. 3. Stamens, each made up of a stalk or filament at the tip of which is the anther, bearing pollen grains. 4. Pistil, which has a swollen basal portion, (i) the ovary, (2) a style, slen- der stalk leading from the ovary, and terminating in (3) a stigma, which is re- ceptive to pollen. Within the ovary are the young ovules, the bodies which become seeds. Fig. 21. — Flax. A, floral diagram — c, calyx; co, corolla; s, stamens; p, pistil. B, median lengthwise section of flower. C, calyx and corolla removed. D, fruit, external view. E, cross-section of fruit. FLOWEKS 49 All the flower parts mentioned a])ove, in the representative flower, are attached to the end of the flower stalk, the receptacle or torus. The calyx and corolla taken together constitute the perianth. We shall see that there are many different sorts of flowers in the families of seed plants. They differ widely in size, form, color, and in the shapes of the various parts. Development of the Flower. — The primordia of flower parts arise as protuberances from the young receptacle (Fig. 15). As a rule, the sepals, petals, stamens and carpels Fig. 22. — Cross-section of a mature lily anther. The pairs of pollen cham- bers unite to form two pollen sacs, filled with pollen grains; s, modified epi- dermal cells at line of splitting. (From a Text-book of Botany by Coulter, Barnes, and Cowles. Copyright by the American Book Company, Publishers.) appear in the order named, as described in the case of the apple flower on page 366. This order of floral succession is said to be acropetal. Although this is the prevaiHng order, there are different types. For example, in some mustards the petals are the last to appear, and in some roses the carpel primordia appear before the stamens. Stamens. — Ordinarily, the anther is held upon a filament 4 50 BOTANY OF CROP PLANTS or stalk. When the filament is absent, the anther is said to be sessile. A cross-section of an immature anther is seen to have four chambers or locules, each with a number of pollen mother cells; each pollen mother cell normally divides to form four pollen grains. As the anther matures the pairs of locules unite, thus forming two pollen sacs in each anther. Finally, each sac spHts open (dehisces) allow- ing the pollen to escape (Fig. 22). Mature Pollen Grain. — When the pollen grain is mature, it consists of a wall surrounding a protoplasmic mass, the essential parts of which are a tube nucleus and a generative nucleus. At the time of pollen germination the latter di- vides into two sperm or male nuclei. Pistil. — The pistil usually consists of an ovary, style and stigma. The seeds are borne in the ovary. A cross-section of a simple ovary shows it to have one locule or chamber with one or more ovules attached to the wall. The tissue to which the ovule or ovules are attached is the placenta. A compound ovary (Figs. 21 and 131) usually has two or more compartments, with an ovule-bearing tissue (placenta) in each. We may also speak of the pistil as simple or com- pound. A simple pistil has one carpel, which is in reality a modified leaf bearing one or more seeds. A compound pistil has two or more carpels. When the carpels are separate, as in the strawberry (Fig. 151) the flower is said to be apocarpous; when united, as in asparagus (Fig. 99), syncarpous. Ovule. — Fig, 23 shows an ovule just before fertilization. A central mass of tissue, the nucellus, is surrounded by an inner and an outer integument, except for a small opening, the micropyle. Within the nucellus is the embryo sac, at this stage consisting of eight nuclei: two synergids, one egg nucleus, three antipodals, and two polar nuclei. They occupy FLOWERS SI about the relative positions in the embryo sac as shown in Fig. 23. Pollination.— This is a mechanical process in which pollen IS transferred from an anther to a stigma. Pollen may be transferred from an anther to the stigma in the same flower. ni/c/eus per/carp — ouier inieo(//rtei /nnermhif/me'ii }Wcelli/s^- embrno sac -' polar nuc/ei aniipodals Fig. 23. Diagram of a simple pistil as seen in lengthwise section showing a single ovule just prior to fertilization. This is termed autogamy or close pollination. Or, pollen may be carried from an anther to a stigma of another flower on the same individual plant. This is called geitonogamy. Again, pollen may be transferred from an anther to a stigma of a flower on another individual plant. This is termed 52 BOTANY OF CROP PLANTS xenogamy, or cross-pollination . Insects, wind and water are the chief agents in the spread of pollen. Fertilization. — Fig. 23 is a diagram of an ovary with a single ovule cut lengthwise. It shows a stage of develop- ment of the ovule about at the time when the pollen grain has reached the stigma. As has been said, the mature pollen grain consists of a protoplasmic mass surrounded by a rather thick wall. Three nuclei (Fig. 24) constitute the important structures in the pollen grain. It absorbs water and nutrient materials from the stigmatic surface, and grows by sending out a tube, known as the pollen tube. The tube grows downward through the stigma, sometimes in a tubular passage, or when necessary, secreting enzymes which digest (render soluble) the walls of cells that are in its path, at the same time deriving nourish- ment from this digested material. As the tube grows, the three nuclei keep pretty close to the tip, the tube nucleus in the lead, with the two sperm nuclei (male gametes) follow- ing. The tube finally reaches the ovule, takes a course through the micropyle and comes into con- tact with the nucellus. This nucellar tissue is penetrated, and after dissolution of the wall at the tip of the pollen tube, the three nuclei are discharged into the embryo sac. The tube nucleus is reabsorbed. One sperm nucleus unites with the egg nucleus (female gamete) to form the zygote, a nuclear mass which contains both the characters of the plant fur- nishing the pollen (paternal characters) and those of the plant fertilized (maternal characters). The union of the male gamete (sperm nucleus of pollen tube) with female gamete (egg nucleus of embryo sac) is fertilization. It is a sperm nuclei ~ — tube nucleus Fig. 24. — Ger- minating pollen grain. {Ajler Bergen and Cald- well.) J-LOWEKS 5,3 sexual process. It is seen to differ fundamentally from pollination which is simply a mechanical process. The fertilized embryo nucleus now develops into a young plant (embryo). The synergids and antipodals are usually dis- organized. In grasses and lilies and some other plants, so- called double fertilization has been observed. One sperm nucleus has been accounted for, as uniting with the embryo nucleus. The other unites with the two polar nuclei of the embryo sac. The body resulting from this triple fusion also carries both maternal and paternal characters. It grows and develops into the endosperm of the seed. Immediately following fertilization, there is a series of changes not only in the ovule which results in a seed, but in the ovary wall as well. Just one pollen tube penetrates the embryo sac to bring about fertilization. Many pollen tubes, even hundreds, may penetrate the style, although comparatively few may function normally. Those which do not, wither and die. We may be sure that every ovule that develops into a seed has been visited by one, and only one, pollen tube. Placentation. — We said that the placenta is the tissue in the ovary to which the one or more ovules are attached. It is traversed by vascular bundles from which branches are given off to the ovules. In currants and gooseberries (Fig. 129) the placentae are on the ovary wall. Such placentation is said to be parietal. In lilies (Fig. 31^), the placentation is axial, or central, that is, the placentae are on the ovary axis. A third kind of placentation is the free central, in which the ovules are attached to an up-growth of the floral axis in the center of the ovary, which is not connected to the ovary wall by radial partitions. Symmetry of Flower. — A flower such as the apple, cherry c* asparagus can be divided into two approximately sym- 54 BOTANY OF CROP PLANTS metrical halves by any diameter (Figs. 156 and 162). Such a flower is said to be radially symmetrical, or adinomorphic, or regular. Contrast this symmetry with that in such flowers as the pea or bean (Fig. 172^), in which there is but one plane through which the flower can be divided to separate it into two symmetrical halves. Such a flower is said to be bi- laterally symmetrical, or zygomorphic, or irregular. Relative Positions of Flower Parts.— In the gooseberry or currant flower (Fig. 129), for example, the ovary is below the stamens, corolla, and calyx, and is said to be inferior. A flower with an inferior ovary is said to be epigynous (above the gynoecium or carpels). When the calyx, corolla, and stamens are inserted on the receptacle below the ovary, the ovary is superior, and the flower hypogynous (below the gynoecium). The flowers of mustards are hypogynous. There is a third intermediate type of flower, well illustrated by the cherry (Figs. 157 and 163), apple (Fig. 157), etc., in which the petals and stamens are inserted on a calyx rim and arise at about the level of the ovary. In such a case the ovary is half-inferior or half -superior, and the flower perigynous (around the gynoecium). Union of Flower Parts. — In the primitive flower type, such as the buttercup, the sepals, petals, stamens and carpels are all separate and distinct. A more or less complete union of the parts of each set of floral leaves may take place. For example, in gooseberries and currants, the sepals are united to form a calyx tube, in the potato flower the petals are united to form a corolla tube, in the cotton flower the stamen fila- ments are joined, and in many instances — onion, apple, orange, and others^ — the carpels are united. The adjectives to describe these various cases are as follows: FLOWERS 55 Separate United Sepals aposepalous sjnsepalous Petals apopetalous sympetalous diadelphous (2 groups) monodclphous (i group) Carpels apocarpous syncarpous Stamens polydelphous Incomplete Flowers. — The representative flower described in a preceding paragraph had all four floral sets of organs present. However, one or more of these sets may be absent, and in this case, the flower is incomplete. Flowers lacking petals are called apetalous (buckwheat). When both sepals and petals are absent, the flower is naked (willows and cotton- woods) . In the majority of flowers, both stamens and pistils, the essential organs of a flower, are present. Such a flower is said to be perfect or hermaphrodite. Some flowers have but one set of essential organs, either stamens, or a pistil. A flower with stamens only, and no pistil, or a flower cluster (inflorescence) composed of such flowers, is said to be staminate. On the other hand, a flower with a pistil but no stamens, or an inflorescence, composed of such flowers, is said to be pistillate. If staminate and pistillate inflores- cences are on different plants, the species is said to be ^'dioe- cious.'^ In some dioecious species (hops), the staminate and pistillate inflorescences are very unlike in appearance, while in other dioecious species (salt-grass, Distichlis), the two unisexual inflorescences are very similar. If staminate and pistillate inflorescences are on the same individual plant, it is said to be '' monoecious. ^^ This is the case in corn, in which the "tassel" (staminate inflorescence) and the "ear" (pistillate inflorescence) are very dissimilar in appearance. Inflorescence. — An inflorescence is a flower cluster. Its shape and the arrangement of the flowers in it difi"er with the kind of plant. There are three general classes of inflores- 56 BOTANY OF CROP PLANTS cences: (i) simple, (2) indeterminate or racemose, and (3) determinate or cymose. The simple type is well represented by the calla lily or tulip, in which one flower terminates the stalk. Mustards and currants have a typical indeterminate or racemose in- florescence. In this, the older flowers are at the base or outside of the flower group and the younger appear in order above them. Moreover, the growth of the inflorescence may continue at the apex. For example, in a cabbage or radish inflorescence, flowers may be opening at the tip, while at the base pods are partially mature. Racemose types of inflorescences are the true raceme, panicle, corymb, umbel, spike, and head. These will be described when they are met with in the family descriptions that follow. The cymose flower cluster is one in which the older flowers are on the in- side, and the younger appear in order toward the outside. The length of a flower shoot is determined by the terminal flower. The inflorescence of chickweeds is a cyme. I CHAPTER VII FRUITS, SEED, AND SEEDLINGS Development of the Seed. — We have seen how a male nucleus of the pollen tube unites with the egg or embryo (female) nucleus of the embryo sac. The fertilized egg then starts upon a series of divisions, and by growth and development, the young plant or embryo is formed. It may be partially or totally imbedded in the endosperm. In some seeds (bean), the endosperm is lacking, and the embryo occupies the entire space within the seed coats. The cells of the nucellus are in part absorbed by the developing embryo, and at most the nucellus is represented by a very thin and compressed layer just within the inner integument. The integuments of the ovule become harder, less permeable, and form the seed coats. The micropyle is still evident in the mature seed as a small opening. The embryo or young plant has three main parts: (i) one or two cotyledons; (2) the hypocotyl, which includes all of the embryo below the cotyledons and terminates in the first root or radicle; and (3) the growing point of the shoot, upon which are a few leaves, making up a bud. The parts of a representative mature seed may be summarized as follows: 1. Seed coats. 2. Nucellus. 3. Endosperm. I Growing point of shoot, with leaves (bud). 4. Embryo { Cotyledon or cotyledons. I Hypocotyl, terminating in the young root or radicle. 57 Seed 58 BOTANY OF CROP PLANTS Development of- the Fruit. — The stimulus of fertilization, • which is not well understood, extends its influence not only to the ovule, but to the ovary as well. Coincident with the changes resulting in the mature seed, the ovary enlarges, and its walls become changed both physically and chemically. The ovary wall (pericarp) has three distinct layers. Named in order from the outside to the inside, these are the exocarp, mesocarp and endocarp. As the fruit develops the changes that occur in these layers may differ. For example, in the cherry or plum, the exocarp becomes the skin of the fruit, the mesocarp becomes thick and juicy to form the fleshy portion of the fruit, while the endocarp takes on a stony character. Fruit and Seed Distinguished.^A fruit, botanically, is the matured ovary, with its seeds, and any parts of the flower which may be closely associated with it. The fruit contains the seed or seeds. For example, the entire bean pod is a fruit; the ''beans" within are the seeds. It is in the case of dry, one-seeded fruits, particularly, that distinction needs to be made between fruit and seed. For example, the buck- wheat fruit (achene) or grass fruit (grain) is commonly called a "seed." But, if development of these is traced and their structure carefully examined, they are seen to be true fruits, with a very thin pericarp (ovary wall) enclosing one seed (Figs. 35 and 115). Kinds of Fruits. — No attempt will be made at this place to give a complete classification of fruits. We will describe the different kinds as we meet with them in the discussions of crop plants. Fruits with a dry pericarp, such as the grain, achene, capsule and pod, are designated dry fruits. De- hiscent dry fruits (capsule, pod, follicle) split open at maturity in a definite way permitting the seeds to escape. Inde- hiscent dry fruits (achene, grain) do not split open at maturity FRUITS, SEED, AND SEEDLINGS 59 •in any definite way. Fruits with a fleshy pericarp, such as the berry, are called fleshy fruits. Germination of Seed.^ — The seed must have an adequate supply of water, oxygen and a suitable temperature in order to germinate. The initiatory stages in germination are the absorption of water and the secretion of enzymes in the seed, which render soluble the stored food material necessary to nourish the growing embryo. This food may be stored in the endosperm, as in all grains, or in the cotyledons, as in beans and peas. The embryo is dependent upon stored food for its initial growth. The sweUing of the seed, due to water absorption and growth of the embryo, ruptures the seed coats, and the young shoot and primary root make their appearance. The cotyledons are brought above ground in some plants (beans, squashes, etc.) and constitute the temporary or seed leaves. They may develop chlorophyll and make food for a while. The true foliage leaves develop, partly at the ex- pense of the food stored in the cotyledons, which gradually dwindle away. In many plants, e.g., all grasses, the coty- ledon remains in the soil. In these the first leaves are true foliage leaves. As soon as the first roots are established, making it possible for the plant to absorb water and mineral nutrients from the soil, and a few leaves are formed, the young plant is capable of making its own food and living an independent life. It has been tided through its early stages of development by food stored in the seed. Generally speaking, large seeds of any given species produce more vigorous seedlings than small ones, and this is probably correlated with a greater abundance of stored food in the former. CHAPTER VIII THE CLASSIFICATION AND NAMING OF PLANTS That subject which deals with the arrangement of plants into groups, based upon their structure and form, is desig- nated Systematic Botany. From the earliest times, man has attempted to classify the large and varied assemblage of plants which he has found on the earth. There have been many systems of classification, some "artificial," some ''natural." An artificial system of grouping plants may use purely arbitrary bases; it may be convenient, but fail to express the natural affinities of plants. For example, in an artificial system, we might choose to put all those plants with red flowers into one group, and those with blue flowers into another class, and so on, thus basing our classification on flower color. Or, we might put trees into one group, shrubs into another, and herbs into still another, thus basing the grouping on size and growth habit. Obviously, we would throw together plants which have no natural relation- ships, and in some cases, separate those which are naturally allied. An artificial system would not take into account the evolutionary tendencies in the plant world. It is agreed that one system of classification is better than another if it more accurately expresses the natural affinities and the evolutionary tendencies of the organisms dealt with. In the early history of systematic botany, the systems of classification were largely artificial. As the knowledge of plants increased, one system supplanted another, and in most cases was an improvement over the old one. One of 60 THE CLASSIFICATION AND NAMING OF PLANTS 6 1 the tirst natural systems of classifying plants (and animals) was that of Linnaeus. The first edition of his. notable work, Systema Naturae, was pubHshed in 1735. There follow the systems of De Jussieu (1789), De Candolle (1819), Eichler (1883), Bentham and Hooker (1826-1883), and Eng- ler and Prantl (i 890-1 896). Two recent systems are those of Bessey (1907), and of Schaffner (191 1). Reproductive versus Vegetative Organs in Classification. — In all higher plants, reproductive and vegetative organs differ markedly from each other. Reproductive tissues are less influenced by environmental conditions than are vege- tative tissues. There may be little resemblance between the vegetative portions of two species, although their repro- ductive structures may be very similar. For example, the strawberry and raspberry have quite different growth form, and their vegetative organs are quite dissimilar, yet the flowers of the two are constructed on the same general plan. On the other hand, two plants with very dissimilar reproduc- tive structures, i.e., having little natural relationship, may resemble each other very closely in their general vegetative appearance. These conditions show that, although vege- tative structures may be modified to a great degree under diverse environmental influences, these same influences do not modify, to an equal extent, the reproductive organs. Hence, on account of this greater stabihty of the reproduc- tive structures of a plant, these are of relatively great value in showing actual relationships, and are of prime importance in classification. GROUPS OF PLANTS A survey of the plant kingdom shows it to be composed of a great variety of plants, differing in size, in structure, in habitat, and in method of living. 62 BOTANY OF CROP PLANTS The "thallus plants" (Thallophytes) include the simplest organisms. This group is divided into two large subdivi- sions, the Alg(B and Fungi. The Algag include the green scums so frequently observed upon the surface of pools, stagnant ponds, reservoirs, ditches and streams. They are also commonly found in tanks and water troughs, and, in such places may render the water objectionable to stock, especially when decay sets in. The brown and red "sea weeds" are also Algae. The Fungi are a large group of plants, probably the best known being the bacteria, the molds of bread, fruit, and cheese, the rusts and smuts of the cereals, the toadstools and mushrooms, the mildews, and the fungi causing such well-known diseases as bhght of potato, alfalfa leaf spot, apple scab, wilt of cucurbit, etc. The "moss plants" (Bryophytes) include the Hverworts, peat mosses, black mosses, and common mosses. They are a group of comparatively sHght economic importance. The "fern plants" {Pteridophytes) are -represented by the true ferns, and closely allied plants such as the horsetails or scouring rushes^ and club mosses. Like the preceding groups, fern plants do not produce seed but reproduce in a much simpler fashion, by spores. The highest and most complex group is the "seed plants" (Spermatophytes) . It includes the GymnospermcB (pines, spruces, firs, hemlocks, cedars, junipers and other cone-bear- ing plants) and the AngiospermcE (higher seed plants or flowering plants). All the common crop plants, of field, orchard, and garden belong to the Angiospermae. In the Gymnospermae the seeds are exposed, while in Angio- spermae they are enclosed in a case, the ovary wall. Angio- spermous plants fall into two groups (subclasses) : (i) Monocotyledones, in which the seeds have one cotyledon, the flower parts are in threes, the leaves are parallel-veined, and THE CLASSIFICATION AND NAMING Or PLANTS 63 the vascular bundles are scattered throughout the ])ith (examples: cereals, onions, asparagus, lilies); (2)- Dicolyle- dones, in which the seeds have two cotyledons, the flower parts are in fours or fives, the leaves are netted-veined, and the vascular bundles are in the form of a cylinder about the pith (examples: buckwheat, beet, apple, cherry, mustard, cotton, melon, potato).' Each of these subclasses is further subdivided. A com- plete classification of some plant, e.g., common alfalfa, will give the principal subdivisions: Spermatophyta, Angiospermae, Dicotyledones, Order Resales, Family Leguminosae, Genus Medicago, Species Medicago sativa. The order ending is usually "ales.'" Orders are subdivided into families. The family ending is commonly " acece^' or "fE." Families are split up into genera, and genera into species. The number of families, genera, and species may be large or small. THE PLANT KINGDOM Thallophytes— '" Thallus plants. " Myxomycetes — slime molds or slime fungi. Schizophytes — "splitting plants. " Cyanophyceae — blue-green algae. Schizomycetes — bacteria. Algae— pond scums, sea weeds, etc. Chlorophyceae — -green algae. Phaeophyceae — brown algae. Rhodophyceae — red algae. 64 BOTANY OF CROP PLANTS Fungi — molds, yeast, mildews, rusts, smuts, toadstools, lichens, etc. Phycomycetes — algal-like fungi. Ascomycetes — sac fungi. Basidiomycetes — basidium fungi. Bryophytes — "moss plants." Hepaticae — liverworts. Musci — mosses. Pteridophytes — "fern plants." Lycopodiales — club mosses, lycopods, quillworts. Psilotales — two small living genera. Sphenophyllales — a single Carboniferous genus. Equisetales — horsetails. Ophioglossales — adder's tongue, moonwort. Filicales — true ferns and water ferns. Spermatophytes — " seed plants. " Gymnospermae — lower seed plants: cycads, ginkgo, coni- fers, joint-firs, etc. Angiospermae — higher seed plants. Monocotyledones. Dicotyledones. PLANT NOMENCLATURE Scientific Name. — The system of nomenclature in use by all biologists today is the so-called binomial system. The scientific name of each plant (and animal) is composed of two words. For example, the scientific name of the common garden bean is Phaseolus vulgaris L. The first word, Phase- olus, is the name of the genus (pi. genera), or generic name; the second, vulgaris, is the name of the species (pi. species) or specific name. The letter "L" following the scientific name of the common garden bean is the abbreviation for Linnaeus. Placed in this position after the name of the plant, it signifies THE CLASSIFICATION AND NAMING OF PLANTS 65 that this species was lirst named and described by Linnaeus. This description may be found in published form. It is the practice of those engaged in the systematic study of plants and animals to record accurately the description, in some recognized scientific periodical, or in a monograph, of any new species they may find. When such is done, the one who names and describes the new plant affixes thereto his name, in full, if short, but usually abbreviated. In some instances, two abbreviations occur after a scientific name, for example, Echinochloa crus-galli (L.) Beauv. This illustrates a case in which a species has been transferred from one genus to another. Linnaeus named the common barnyard grass Panicum cr-us-galli L. In his revision, Beauvois trans- ferred £he common barnyard grass to the genus Echinochloa still retaining the specific name, crus-galli. Nomenclature rules state that when a species is transferred in this manner from one genus to another, the original author (in this case, Linnaeus) must always be cited in parenthesis, fol- lowed by the author (in this case, Beauvois) of the new binomial. Botanical varieties or subspecies are often printed as trinomials, for example, the bush variety of Phaseolus vulgaris is written Phaseolus vulgaris nanus or Phaseolus vulgaris var. nanus. Agricultural "varieties" are desig- nated by common names, for example, in beans, there are such varietal names as Early Bountiful, Black Valentine, Giant Stringless, Green-pod, etc. Scientific names are in Latin. This is probably the most universal language, which fact was recognized by Linnaeus, and hence he adopted it in his system of nomenclature. The species and genus agree in gender. For example, Brassica rapa (turnip), Triticum aestivum (common wheat), and Rubus villosus (northern dewberry). 66 BOTANY OF CROP PLANTS Descriptive Nature of Specific Names. — Specific names are commonly descriptive. They may be descriptive of (i) some plant character or habit, (2) habitat, or (3) dis- tribution; and, in some instances (4) the species may bear the name of an individual. By far the largest proportion of specific names is descriptive of some striking habit or character of the plant. For example, the trailing or pro- cumbent Trijolium (clover) is Trifolium repens {repens, creeping); the sweet clover with white flowers is Melilotus alba {alba, white); the narrow-leafed crab-apple is Malus angustifolia (angustus, narrow — folium, leaf). In Vitis riparia, the streamside grape, riparia is descrip- tive of this species' habitat. The common black-cap rasp- berry is Rubus occidentalis; here the specific name* means "western." Again, in Vaccinium canadense, the Canada blueberry, the specific name indicates geographical distribu- tion. The systematist frequently uses the name of an indi- vidual for the specific name. This may be done as a token of friendship, or recognition of distinction, or to indicate the finder of the new form. For example, Prunus besseyi, is after the well-known botanist, Charles Bessey. The i ending is the Latin genitive, signifying "of Bessey." Scientific Name versus Common Name. — There are dis- tinct advantages connected with the knowledge and use of scientific names. Often the same species has many common names. Again, several distinct species often may go by the same common name. The use of one scientific name will do away with much misunderstanding as to what plant is actually referred to. General References Bailey, L. H.: The Standard Cyclopedia of Horticulture. The Macmillan Co., 1914. Baillon, H.: Histoire des plantes. Paris, 1894. THE CLASSIFICATION AND NAMING OF PLANTS 67 Bextham, Ct., and HoofcER, J. D.: Genera Plantarum. London, 1862-1883. Brixton and Brown : An Illustrated Flora of the Northern States and Canada. Scribncrs, New York, 1913. Card, Fred W.: Bush-fruits. The Macmillan Co., 1909. CoRBETX, L. C: Garden Farming. Ginn & Co., 1913. Coulter, J. M., Barnes, C. R., and Cowi.es, H. C: A Textbook of Botany. American Book Co., 191 1. De Candolle, Alphonse: The Origin of Cultivated Plants. D. Appleton & Co., 1892. Engler and Prantl: Die naturlichen Pflanzeufamilien. Hunt, T. F.: Forage and Fiber Crops in America. Orange Judd Co., 1908. Knxjth, Paul.: Handbook of Flower Pollination. Translation by J. R. Ainsworth Davis. Oxford, Clarendon Press, 1906. Montgomery, E. G.: Productive Farm Crops. Lippincott Co., 1916. Percis'al, John.: Agricultural Botany. Henry Holt & Co., 1905. Piper, Charles V.: Forage Plants and Their Culture. The Macmillan Co., 1914. Shepperd, J. H.: Root Sj^stems of Field Crops. N. D. Agr. Exp. Sta. Bull. 64: 525-536, 1905- Strasburger, E., Noll, F., Schenck, H., and Schimper, A. F. W.: A Text- book of Botany. Macmillan Co., 1912. Ten Eyck, A. M.: The Roots of Plants. Kans. Agr. Exp. Sta. Bull. 127: 199-252, 1904. Vilmorin, M. M.: The Vegetable Garden. John Murray, London, 1905. WossiDLO, Paul.: Leitfaden der Botanik. Berlin, 191 1. PART II CHAPTER IX GRAMINEiE (POACE^), GRASS FAMILY No family of plants is of greater economic importance than the grass family. It has several thousand species, among which are the "grains" (such as wheat, oats, barley, corn, rice, and others) and the meadow, pasture and range grasses. The grasses grown for "grain" were the first plants to be cultivated by the human race. Members of this family are widely distributed over the surface of the earth, from tropical to polar regions and from low to very high altitudes. In many parts of the world, grasses form a dominant part of the plant covering. Examples of extensive grass associa- tions are meadows, steppes, and savannahs. Meadows are moist grass lands and may occur in all climates. Steppes are dry grass lands. The Old World steppes of Russia, Hungary, Roumania, and Spain, the plains of the Western United States, and the pampas of South America are excellent examples. Savannahs are dry grass lands with scattered trees. The best examples of these are the llanos of Venezuela, and the patanas of Ceylon. Habit of Plants. — Most grasses are low, erect herbs. A few, such as the bamboos, are shrubs or trees. Bamboo has a woody stem which may reach a height of loo feet or more. Some grasses are trailing, one or more being re- ported as climbing over trees lOO feet high. Others, like 69 70 BOTANY OF CROP PLANTS rice cut grass (Homalocenchrus) are feeble climbers or support themselves by means of numerous hooked prickles on their leaves. Many of our common pasture and meadow grasses, and all the cereals, complete their life period in one season. Such plants are said to be annual. In cool climates, certain grasses behave as winter annuals, living through the winter as small plants and sending up flower stalks the following spring. So-called "winter" or "fall grasses" behave in this manner. A number of grasses, such as the pernicious quack grass {Agropyron repens), lawn grass {Poa pratensis), and others, are perennial, i.e., with a course of hfe extending over three or more seasons. Roots. — The root system of grasses is fibrous, that is, composed of numerous slender roots of about equal diameter. No grasses, at maturity, possess a tap-root system, as that of radish, dandelion, beet, and others. In this there is a strong leading central root. The primary roots, those that arise directly from the seed, are temporary, dying after the permanent roots are able to support the plant. The perma- nent roots arise from that portion of the stem which ex- tends from the germinating seed to the surface of the ground. These roots are always produced at about the same distance below the surface, regardless of the depth at which the seed is planted (Fig. 3) . Grasses are classed as shallow-rooted plants. However, great variation has been observed in the depth to which the roots penetrate, some extending to depths which cannot be considered as shallow. Roots of buffalo grass {Buchloe) sometimes go to a depth of 7 feet. Rye roots have been found penetrating to a depth of 3 feet, corn 33^^ feet (Fig. 56), emmer and spelt 33^ feet, and wheat more than 4 feet. Roots may break through the sheaths (that part of the GRAMINE^ (POACE^), GRASS FAMILY 71 ^s.-l(°J blade Fig. 25. — Wheat plant showing the general habit of grasses. 72 BOTANY or CROP PLANTS leaf which is wrapped about the stem) of the first few leaves, or spring freely from underground stems. They may also arise from joints above the ground line, as in corn. If such aerial roots reach the ground they may serve as supporting or "prop" roots (Fig. 56). Stems. — General Characteristics. — The stems of grasses are called culms. They are cylindrical (rarely flattened), and divided into sections (internodes) (Fig. 25) which are usually hollow, but some- times filled with pith, as in corn. When young, the in- ternodes are solid, but, as the stem enlarges, the central portion is ruptured and a hollow is formed. The nodes (Fig. 25), the enlarged joints between the internodes, are solid. Enlargement of the nodes is due partly to a thickening of the leaf base at each node (Fig. 26) and partly to enlargement of the stem itself. In most grasses, the part of the culm within the sheath remains soft and continues to grow or retain the power of growth after the portion not in the sheath has ceased growth, or lost the abiHty to grow. The youngest part of each internode is at its base, surrounded by the basal swelhng of the leaf sheath (Fig. 26). Each internode has its own growing zone. Lodging. — It is customary to speak of a grass as "lodged" Fig. 26. — Barley. .4, portion of leaf at juncture of leaf and blade; B, stem cut in median lengthwise section. X 23-^. GRAMINE.E (POACE^), GRASS FAMILY 73 when its stems are bent over and caused to lie on the ground by the mechanical action of a high wind, or driving rain. Some grasses lodge more easily than others. This may be due either to their greater height, heavier fruiting head, or to a lack of strengthening material. Moreover, it has been shown that an excessive amount of available nitrates in the soil favors lodging. As it has been demonstrated that the application of nitrate fertilizers to a soil tends to suppress the amount of silicon taken in by the wheat plant, the greater frequency of lodging of plants grown on such a soil may re- sult from a stem weakness caused by a lack of silicon within them. However, the causes of lodging are not well known. The stems of lodged grain are not necessarily broken. The reverse is the case, as is shown by the fact that the lodged culm has the power of partially or entirely erecting itself. This power is exhibited more strongly in growing or imma- ture culms than in old ones. When a grass stem is lodged, the cells on the lower side of each internode, at its base, grow more rapidly th3.n those on the upper side, and, hence, the stem curves upward. This behavior is a response to the stimulus gravity. The manner in which gravity acts upon an organ as a stimulus has not been demonstrated. However, it has been experimentally determined that all plants make pronounced adjustments in their growth in response to gravitation. This property is called geotropism. Tillering. — It is a common observation that trees, shrubs and most herbaceous plants produce side branches in regular order, and that these arise at the nodes along the stem. The side branches of the grasses are not so obvious as those in trees and shrubs, for example, for the reason that the culms of most grasses produce branches from the lower nodes only. This branching in grasses is known as ''stooling," '' tillering," or "mooting." The individual branches are known as "tillers" 74 BOTANY or CROP PLANTS (Fig. 27), and the entire mass of branches is the "stool." Common cereals, such as wheat and oats, invariably pro- duce a number of tillers, sometimes as many as 50. The tillers from the primary culm may produce tillers (lateral branches) and these in turn other tillers, so that under favor- able conditions several dozen culms may result from a single seed. As the internodes are much shortened, the branches tertiary stem —scale leaf ' / p~^-S€con6ary stem ~~-primar\i stem --^crown roots L—^ram remains l^^sj)nmary roots Fig. 27. — Diagrammatic representation of tillering in cereals. {After Schindler.) appear to come out at one point. In the wheat plant, two or three weeks old, three or four buds may be found, one in the axil of each leaf. Tillering results from the outgrowth of these lateral buds. Tillering activity varies with the species, the individual, and environmental conditions. In general, winter grains tiller more than summer ones. It is dependent especially upon the depth of seeding. There seems to be an optimum depth, which varies with the sort of grass. The average depth of the tillering node in cereals is about i to 2 centi- GRAMINE^ (pOACEiE); GRASS FAMILY 75 meters. Tillers are produced freely in moderately warm, sandy soil. The number of tillers is also increased by a large amount of reserve material in the seed, and by high soil fertility, and by thin seeding. The effect of this last factor is well shown in the following data taken from the Nebraska Experiment Station Bulletin 127: Tillering of Oats Pecks of seed sown per acre Stems per lOO plants Total number of stems per acre 4 8 16 466 279 140 1,419,000 1,732,000 2,283,000 The production of tillers in the small grains is altogether desirable from the farmer's standpoint, as it is an important factor determining yield. Bulbous Grasses.— In a few species such as timothy (Phleicm pratcnse) and tall oat grass (Arrhenatherum elatius), some of the lower, short internodes are enlarged into bulb- like bodies containing a store of nourishment. Rhizome-bearing Grasses. — Perennial grasses usually have rhizomes or rootstocks, horizontally elongated under- ground stems, which give rise to erect annual stems that bear foliage leaves and flowers. These underground stems are very efficient as reproductive organs, for, as a result of their elongation in the soil, the plant is able to invade areas already occupied by other plants. Furthermore, each root- stock is capable of budding a new plant at every node, and should it be dragged from the ground by cultivating machin- ery and broken into a number of separate pieces, each piece will give rise, under favorable conditions, to a new plant. Quack grass (Agropyron repens), and many other of our 76 BOTANY OF CROP PLANTS worst weeds, owe their obnoxious character mainly to the possession of rootstocks. Such plants are not dependent upon seed production alone, but in addition spread by means of their rootstocks. The rootstock is a storehouse of food material, and although the leaves and stems above ground may be destroyed, new shoots are sent up from it, drawing upon the stored food supply. For this reason, perennial weeds of all kinds are difficult to eradicate. Any method of elimination adopted is based upon the knowledge that the food stored in the underground stems is made in the green leaves; therefore, the development of green leaves must not be allowed. Rhizomes of grasses bear brown or colorless sheathing scales (rudimentary leaves) containing in their axils active buds which may develop into erect stems. Under favorable conditions, roots are produced at the nodes of the rhizomes. Grasses possessing rhizomes are rhizomatous. When the internodes of the rhizomes are very short, the culms are close together, and the grass is known as a tufted grass or as bunch grass, as in meadow fescue {Festuca pra- tensis). Many of our most valued range grasses have the bunch habit. When the internodes are long, the culms are more widely separated, and a creeping grass, as awnless brome grass {Bromus inermis), is the result. Stoloniferous Grasses.- — When the horizontal stems are at or above the surface of the ground, they are called runners or stolons, as in buffalo grass {Buchloe dactyloides) . Outside of the grass family, the runners or stolons of strawberry are very typical. Stolons are about as effective as rhizomes in propagation. They usually produce a more open, loose tuft. This is due to the long internodes. Stoloniferous grasses do not produce as solid and uniform a turf as rhost rhizomatous grasses. Neither is it likely that the former would produce a GRAMINE.15 (pOACEM), GRASS FAMILY 77 sod that would be as enduring under conditions affecting the sod surface, such as heavy trampling or close grazing. Leaves.^ — General Characteristics. — In grasses, a single leaf arises at each node. Leaves disposed in this fashion along a stem are said to be alternate. If one starts with a certain leaf, the leaf next above or next below, is on the opposite side of the stem, i8o° around the circumference. This arrange- ment gives two vertical rows of leaves opposite each other on the stem. Such an arrangement is said to be two-ranked, distichous, or one-half spiral. We shall have occasion further on to discuss other leaf arrangements, and to emphasize the fact that leaves are developed on a stem in a definite order. The grass leaf in general appearance is unlike that of such common plants as apple, cottonwood, maple and beet. In these the leaf has a definite, narrow stalk or petiole and an expanded blade (Fig. 159). The grass leaf is divided into two distinct parts, sheath and blade (Fig. 26). The sheath represents the leaf base, and forms a tube around the culm. At the base of the leaf sheath, there is a distinct swelling. The more or less flattened part of the leaf which spreads away from the culm is the blade (lamina). The blades are parallel- veined, that is, have many veins, about equal in size, running parallel, and joined by inconspicuous vein- lets. Parallel venation is characteristic of the leaves of grasses, sedges, rushes, Hlies and most all other monocoty- ledonous plants. Growth of Leaves. — In the early life of the grass plant, leaves grow faster than internodes. This results in a tuft of leaves. Some leaves elongate indefinitely. The tip of the leaf blade is the oldest portion. The growing point is at the base of the blade. This growing zone, as a rule, is marked by a whitish or light green semicircle (Fig. 26). 78 BOTANY OF CROP PLANTS The upper portion of the leaf may therefore be removed without permanent injury to the plant. This is well shown in the rapid recovery of the leaves of lawn grass after mowing, and of pasture grasses after grazing. Scales and Bracts. — Reduced leaves in the form of scales and bracts occur in grasses. Such reduced leaves are termed "scales" when they appear lower on the stem than the foliage leaves, and "bracts" when higher. For example, the reduced leaves at tillering nodes are "scales" (Fig. 27), while the reduced leaves (glumes) in the inflorescence are "bracts" (Fig. 28). Scales and bracts seldom possess chlorophyll (green coloring material in plants), and, hence, are incapable of carrying on synthesis of carbohydrates. The scales and bracts in grasses have the same one-half spiral arrangement as the foliage leaves and although they may be very close together on the axis, careful observation shows them to have this typical arrangement of all grass leaves. Ligule. — ^At the junction of the sheath and blade is a membranous or cartilaginous ring or fringe, the ligule (Fig. 26). It is next to the culm, and varies in size, shape, and hairiness in different species of grasses. The ligule is sometimes absent. Auricle (Fig. 26). — This is a more or less pointed, thin, ear-like structure projecting from the leaf edge at the junc- tion of sheath and blade. It often clasps the stem but may be more or less twisted and bent away from it. It varies greatly in size and shape. In the tribe Hordea?, the auricles are characteristic. They are entirely absent in some species. Inflorescence. — The grass inflorescence (flower cluster) consists of a number of groups of flowers, each group being called a spikelet. The spikelet is, in fact, the unit of the GRAMINEiE (rOACE^), GRASS FAMILY 79 av^n -t-^ lemmas ^glumes grass inflorescence. The spikelets are attached either directly or indirectly to a main axis, the rachis (Fig. 28). The three common sorts of grass inflorescences are the spike, panicle, and raceme. When the rachis is unbranched, so that the spikelets are not borne on individual stalks, but are attached directly (sessile) to the rachis, the result is a spike. The inflorescences of wheat, barley, and rye are good examples of spikes. Usually, each culm bears a single spike. In the raceme, each spike- let is borne on a short branch of the rachis, as in sheep's fescue (Fesiuca ovina). In the panicle, the primary branches of the rachis branch one or more times (Fig. 44). These branches may be long and widely spreading, as in oats and brome grass, or short and rather appressed to the rachis, as in timothy, meadow foxtail (Alopecurus) , and Koeleria. Different types of inflorescences be- sides the spike, raceme and panicle will be met with in some of the following families. We shall also see that these three types are not confined to the grass family, but are in fact exceedingly common among seed plants of all kinds. Spikelet. — The spikelet is the unit of inflorescence in grasses. A typical spikelet, such as that of oats (Fig. 46), or wheat (Fig. 28), for example, consists of a shortened axis, the rachilla, bearing a number of chaff-like, two-ranked (distichous), overlapping bracts (glumes of some authors). The two lowermost bracts are empty, that is, do not bear flowers in their axils. Fig. 29 shows a dissected wheat rachij Fig. 28. — Single spike- let of common wheat (Triticum sestivum). X 2. So BOTANY OF CROP PLANTS spikelet with its parts removed in order. Each spikelet is subtended by these two empty bracts. Following the sug- gestion of Piper, we shall designate these two basal, empty bracts as ^^ glumes.'" The lower of these is the "first glume," the upper the "second glume." Above the two glumes, on the rachilla, are one or more bracts; each one of these is known as a lemma (flowering glume and inferior palea of some authors). Normally, there is a flower in the axil of each lemma. Opposite each lemma is a two-nerved, two- keeled, bract-like structure, the palet (the palea, prophyllum. tjj ^lume rachis Fig. 2g. — Spikelet of common wheat (Triticum asstivum) dissected, the parts removed in order. bracteole, and superior palea of some authors). Its back is turned toward the rachilla. It frequently envelops the other parts of the flower with its infolded edges. The palet is never awned (bearded). While the glumes and lemmas are inserted on the rachilla, the palet is inserted on a very short flower stalk (pedicel) . At the base of the ovary, on the side opposite the palet, are two minute scales, the (anterior) lodicules (Fig. 30). Inside the palet, and placed farther up on the flower stalk, are three stamens and a single pistil. Thus we see that in the typical spikelet there are two glumes GRAMINE^: (pOACE.T.)j GRASS FAMILY 8l subtending one or more lemmas; in the axil of each lemma is a flower, and each flower consists of a palet (outer perianth), two lodicules (inner perianth), three stamens, and a single pistil. Each stamen has a large anther. The filament (stalk) is attached at the base of the anther, but on account -z^^^lodtcvles Fig. 30. — Wheat flower with lemma removed; considerably magnified. of the extreme sagittate nature of the latter, it appears versatile. The ovary is one-celled, one-seeded, bears two. styles and two feathery stigmas. There are many deviations from the typical form of spikelet. In Colcan- Ihus, the empty glumes are absent; in Nardus, solitary; in Homalocenchrus, mere rudiments. In some Agrostis species, the palet is rudimentary. It is not always two-keeled, but generally two-nerved. There is a third (posterior) lodicule in some grasses. Although the stamens are as a rule three, there are six in most bamboos and in rice (Oryza). In Streplochceta and Oryza (oc- casionally), there are three styles, and only one in Nardus. 6 82 BOTANY OF CROP PLANTS The amns or beards are brittle-like structures on lemmas or glumes, usually on the former. They are commonly termi- nal, as in wheat, or dorsal (attached to back of lemma), as in oats. Zoebel and Mikosch, working with two-rowed and six-rowed barleys, arrived at the conclusion that awns are transpiring (water-losing) organs. They noted that bearded barley spikelets transpired more than artificially beardless ones of the same sort under similar conditions. They also observed that, at the time of kernel development, transpira- tion from the spikelet was most intense, probably corre- sponding to the time of greatest movement of reserve ma- terial to the kernel. Up to 1906, Hackel reports 67 species of cleistogamous grasses. As compared with flowers that open, cleistogam- ous ones generally have reduced lodicules, smaller anthers, a shorter pistil, and less pollen. In a few cases {Panicum clandestinum) for example, chasmogamous spikelets and cleistogamous spikelets may occur in the same inflorescence. According to Koernicke, two-rowed erect-eared barley (Hordeum distichon erectum) bears only cleistogamous flowers. Pollination. — Wind is the chief agent in the dissemination of grass pollen. In all grasses the pollen is light and dry, and hence easily blown. Insects play a very unimportant part in this process. Most grass flowers open to shed their pollen, that is show chasmogamy. In some grasses, however, the glumes do not spread apart, thus allowing the stamens and pistils to be- come exposed. Flowers that do not open are said to show cleistogamy. Fruit. — In all grasses, the fruit is one-seeded, dry, and does not spht open at maturity to allow the seed to escape. The pericarp (ovary wall) is firmly attached to the seed coat. GRAMINE.E (i'OACE.e), GRASS FAMILY 83 The grass fruit is called a grain or caryopsis. There is an abundance of starchy endosperm. Sometimes the grain is closely adherent to the palet and lemma, as in most barleys and oats. Phylogeny of Grasses. — The history of the evolution of a group of organ- isms is phylogeny. What is the origin of the grasses? Are they primitive forms, the progenitors of such closely related groups as the lilies and other common monocotyledonous plants; or are they a reduced group? By those who hold the latter view, which is more widely accepted, grasses are con- sidered to have come from lily-Hke plants by a reduction and modification of a number of parts of the flower. Examination of the floral diagram of a typical lily flower is shown in Fig. 31. It has two sets of floral segments (which together constitute the perianth) which alternate, two whorls of stamens, three in each whorl, and a pistil divided into three chambers, hence tri-carpellary. The stamens of one whorl alternate with those in the other; those of the outer whorl alternate with the inner segments of the perianth. The three carpels alternate with the inner stamens. In Fig. 31 is shown the floral diagram of a grass flower with the rudimentary or missing parts shaded. According to the view that grasses are reduced lilies, there was a reduction in the lobes of Fig. 31. — Diagram of A lily flower, and B grass flower showing homologous structures. A, /, bract; ax, axis; op, outer perianth; ip, inner perianth; s, sta- mens; c, tricarpellary ovary. B, shaded struc- tures are aborted; le, lemma (bract); ax, axis; p and p', palet (outer perianth); I and I', lodicules (inner peri- anth) ; s and s', two whorls of stamens; c, tricarpellary ovary. (B after Schuster.) 84 BOTANY OF CROP PLANTS ' the pistil from three to one, a loss of one whorl of stamens, and a reduction in the number of perianth lobes. Although commonly assumed to be one-carpelled, the grass pistil is really tri-carpellary. This latter view is held by a number of morphologists (Doell and Goebel), and recently has been quite conclusively demonstrated by Walker and Schuster. In all grasses, the pistil has three fibro-vascular bundles. Two of these extend to the style branches and the third (dorsal) extends to the dorsal lobe of the pistil or to the third rudimentary style branch, when present. This third bundle bears the ovule. In StreptochcEta and Bambusce, there are three styles. Furthermore, it should be noted that the three vascular bundles stand in regular alternation with the second whorl of stamens and the inner whorl of the perianth. Rowlee, in a study of Arundinaria, a bamboo, concluded that the lodicules represent the inner perianth whorl. The common view, as presented by Hackel, has been that lodi- cules are bracts. Schuster's researches substantiate those of Rowlee. He finds that, although two lodicules is the com- mon number, a third (anterior) one occasionally occurs (in Bambusae); that the two (posterior) lodicules are not bound together at first but originate separately; that in one grass genus {Streptochaeta), at least, the three lodicules are inde- pendent. From these studies, it appears that the lodicules, morphologically, are to be considered as the inner perianth whorl. The same worker (Schuster) considers the palet to represent the outer perianth whorl of this lily-like flower. The palet is usually two-keeled or two-nerved. There are cases in which the palet is divided into two parts, and in which there is a third part in a rudimentary condition. In the majority of grasses, the two parts of the palet arise from separate primordia, later growing together to form a single GJRAMINE.I-: (pOACK-t;), GRASS FAMILY 85 slruclurc; the third, outer i)erianth whorl aborts. In this connection it should i)e noted that the ])alet of cinkorn [Triticiim monococcum) divides into two parts, at maturity, on the median line, each half bearing a keel (Fig. 37). According to the view presented above, the grass spike- let is interpreted as a modified branch, bearing a number of distichous bracts. The two lower bracts (glumes) are sterile. The flowers occur in the axils of the lemmas. The flower is of the lily type. The outer perianth whorl is rep- resented by the palet, the inner by the lodicules; one whorl (inner) of stamens (usually, not always) is aborted; the pistil is three-carpelled. Hence, we see that grasses are derivates of a normal monocot flower. Grass-like Plants. — Grasses are closely related to the sedges (Cyperacecp). Sedges, however, have solid stems, usually three-angled, leaves with closed sheaths, and the fruit an achene. In the achene the pericarp or mature ovary wall is not firmly grown to the seed coat which immediately adjoins on its inner surface. The achene and the grain are both dry, one-seeded fruits that do not split (dehisce) at maturity, but in the grain the mature ovary wall is closely adherent to the seed coat. In grasses, as pointed out on page 77, the leaves are two-ranked or distichous. In sedges, however, the leaves are three-ranked, or one-third alternate. Sedges grow in wetter situations than grasses and are often harsher in texture, due to the deposition of silica in the stems and leaves. There are certain rushes (Juncacecs), other than rush-like sedges, which are grass- like in appearance. These, however, are distinguished from the grasses by the. presence of a perianth of six distinct glume- like segments. 86 BOTANY OP CROP PLANTS References Baillon, H.: L'evolution de I'inflorescence dans les Graminees. Bui Soc. Linn. Nord, France, 1894, 1123-1128. Bruns, E.: Der Grasembryo. Flora, 76: 1-33, 1892. Chase, Agnes: Notes on the Cleistogamy of Grasses. Bot. Gaz,, 45: 135- 136, 1908. DoELL.: Untersuchungen uber den Bau der Grasblute. Jahresber. Mann. Ver. f. Naturk., 1868, xxxiv and 1870, xxxvi. GoEBEL, K. : Ein Beitrag zur Morphologie der Graser. Flora, 1895, Erganzungsband. GuERiN, P.: Recherches sur le development du tegument seminal et du pericarpe des graminees. Ann. Sci. Nat. Bot., 9: 1-59, 1899. Hackel, E.: liber das Aufbluhen der Graser. Bot. Ztg., 33: 432, 1880. Untersuchungen uber die Lodiculse der Graser. Engler's Jahrb., i: 336- 361, 1881. The true grasses. Transl. from German by F. L. Scribner and E. A. South worth. Henry Holt & Co., New York, 1890. Uber Kleistogamie bei den Grasern. Osterr. Bot. Ztschr., 55: 81-88, 143-154, 180-186, 1906. Hitchcock, A. S.: A Text-book of Grasses with Especial Reference to the Economic Species of the Unites States. ' The Macmillan Co., New York, 1914. JUMELLE, Henri.: Note sur la constitution du fruit des Graminees. Compt. Rend. Acad. Sci. (Paris), 107: 285, 1888. Kennedy, P. B.: The Structure of the Caryopsis of Grasses with Reference to Their Morphology and Classification. U.S. Dept. Agr., Div. Agros., Bui. 19, 1900. Lamb, William H.: The Phylogeny of Grasses. Plant World, 15: 264-270, 1912. Piper, C: The Terminology of the Parts of the Grass Spikelet. Science, n. s., 23: 789-790, 1906. RowLEE, W. W.: The Morphological Significance of the Lodiculesof Grasses. Bot. Gaz., 25: 199-203, 1898. Schuster, Julius: Uber die Morphologie der Grasblute. Flora, 100: 213- 266, 1910. Walker, E. R.: On the Structure of the Pistils of Some Grasses. Thesis, Univ. Nebr., 1906. Ward, H. Marshall: Grasses, a Handbook for Use in the Field and Laboratory. Cambridge, 1901. True, Rodney: On the Development of the Caryopsis. Bot. Gaz., 18: 212-226, 1893 (contains bibliography on development of grain). GRAMlNEiE (POACE^), GRASS FAMILY 87 CEREALS Cereals are those grasses which are grown for their grain. Buckwheat is sometimes considered a cereal because its fruit (achene) is ground into flour, but it is not so considered here. Buckwheat, flax, and others, which are often raised for their seed or fruit, but are not grasses, are discussed wherever they happen to come in the botanical order of treatment followed here. , Key to Groups (Genera) of Important Cereals^ 1 What is a "key," and how is it used? Throughout the following pages there will be a number of "keys." A "key" is a convenient form for dis- tinguishing one plant from another, or one plant group from another. It presents in concise form the principal differences between the plants con- sidered. It also enables one to determine the proper classification of an unknown plant. Most of the "keys" in the following pages are "artificial," that is, the characters used are obvious ones. The "keys" herein are con- structed on the dichotomous plan, i.e. by twos. The entire number of groups under consideration, whether these be species, genera, families, or higher divisions, is first divided into two subgroups; each of the subgroups is sub- divided into two groups, and so on. The alternatives are equally indented on the page. In the key to the genera of cereals, they are first divided into two large groups, the first including Zea, Oryza, Andropogon and Millets; and the second, Avena, Secale, Trilicum and Hordeum. It is seen that those genera of the first group have "spikelets falling from the inflorescence entire . . ." while those of the second group have "spikelets falling from the in- florescence without the glumes. . . " Each of the two large groups is again separated into two subdivisions. For example, the genera Avena, Secale, Triticum and Hordeum, are subdivided on the basis of their inflores- cences. Avena has a panicle inflorescence, while Secale, Triticum, and Hor- deum have a spike inflorescence. Let us suppose that we have a cereal in hand, the genus of which we wish to determine. First of all, it would be necessary to decide whether the "spikelets fall from the inflorescences entire . . . ;" or "spikelets fall from the inflorescence without the glumes . . . ;" if it has the characters of the second alternative, we know it is either oats, rye, wheat or barley. Should the specimen in hand have a spike inflorescence, oats is eliminated from consideration, and the plant must be either rye, wheat or barley. If, 55 BOTANY OF CROP PLANTS by examination of this unknown plant, we find now that there are "three spikelets at each joint of the rachis," it must belong to the genus Hordemti (barley). The "key" shows many of the characteristics of a group. Consider Trilicum (wheat), for example. One can see by the key that "spikelets fall from the inflorescence without the glumes, which remain attached to the rachilla; spikelets one-many-flowered; rachilla often produced beyond the upper glume; grain with a longitudinal furrow; tuft of hairs at tip of ovary." Furthermore, that the "inflorescence is a spike"; that there is "one spikelet at each joint of the rachis," and the "glumes are not bristle-like, but broad." Spikelets falling from the inflorescence entire (glumes attached to grain), one- flowered, or if two-flowered the lower one staminate; rachilla not pro- duced beyond the flowers; grain without a longitudinal furrow; no tuft of hairs at tip of ovary. Flowers staminate and pistillate; borne in separate inflorescences on the same plant, i.e., monoecious (Fig. 57), Zea (maize or Indian corn). Flowers perfect or staminate; when the staminate are present, borne in same inflorescence with perfect. Spikelets much compressed laterally (Fig. 75), Oryza (rice). Spikelets cylindrical or somewhat compressed dorsally. Lemma and palet thin and papery, much more delicate in texture than the empty glumes (Fig. 71), Andropogon (sorghum, milo, broom corn, etc.) Lemma and palet, at least of perfect flower, never thin and papery, parchment-like or leathery, hard and shiny, very different in color and appearance from the glumes (Fig. 83), Chcelochloa, Echinochloa, Panicuni, Pennisetum (millets). Spikelets falling from the inflorescence without the glumes, which remain attached to the rachilla; spikelets one to many-flowered; rachilla often produced beyond the upper glume (Fig. 47); grain with a longitudinal furrow (Fig. 34); tuft of hairs at tip of ovary (Fig. 34). Inflorescence a panicle (Fig. 45), Avena (oats). Inflorescence a spike. One spikelet at each joint of rachis. Glumes bristle-like (Fig. 55), Sccale (rye). Glumes not bristle-like, broad (Fig. 28), Triticum (wheat). Three spikelets at each joint of rachis (Fig 49), Hordcmn (barley). Key to Small-grain Seedlings^ 1 This key is taken verbatim from Carrier. The "collar" is a narrow band, usually of different color from the sheath and blade, at the junction of leaf and blade. The "claw-like appendages" are the auricles. ('.KAMiNE-i-: (foace^:), grass family 89 Collar without claw-like appendages, Oats (Avena saliva). Collar with claw-like appendages which clasp the stem more or less. Claws bair>'. Sheaths and blades finely pubescent, soft, and velvety, Emmer {Tr'Ui- cum dicoccum). Sheaths and blades not pubescent. Collar and claws large, Spelt {Triliciim spclta). Collar and claws slender, Wheat {Triticum cestivum). Claws not hairy. Collar and claws large and prominent. Nerves of blades not prominent, upper surface rough. Barley {Ilor- dciitn sativum). Nerves of blades broad and prominent, smooth on upper surface, Polish wheat {Tritiatm polonicum). Collar and claws slender. Blades and sheaths sparsely hairy. Rye {Secale cerealc). Blades and sheaths free from hairs. Durum wheat {Triticum durum). References Aaronsohn, a.: tjber die in Palastina und Syrien wildwachsend aufgefun- denen Getreide-arten. Verhandl. K. K. Zool. Bot. Gesell. Wien., 59:385-590, 1909- Contribution a I'histoire des cereales. Bui. Soc. Bot. (France), 1909. Atterberg, a.: Die Nachrcife des Getreides. Landw. Versuchstat., 67: 129-143, 1907. C.'VRLETON, M. A.: The Small Grains. The Macmillan Co., 1916. Carrier, Lyman: The Identification of Grasses by Their Vegetative Char- acters. U. S. Dept. Agr. Bull. 461: 1-30, 191 7. Deherain und Dupont: tJber den Ursprung der Starke im Getreidekorn. Comp. Rend. Acad. Sci. (Paris), 133:774, 1902. Desriot, a.: Les cereales, 2 ed., Paris, 1910, Hachette et cie. Ekkert, F. : tJber Keimung, Bestockung und Bewurzelung der Getreide- arten. Inaug. Diss. Leipzig, 1873. Fruvvirth, C: Das Bluhen des Getreides. Jahrb. Deut. Landw. Gesell., 22: 68-75, 1907- Fruwirth, W.: Die Ziichtung der landwirtschaftlichen Kulturpflanzen. Berlin, 1910. KoERNiCKE, F. and Werner, H. : Handbuch des Getreidesbaues. I. Die Arten und Varietaten des Getreides. II. Die Sorten und der Anbau des Getreides. Berlin, 1885. tJber die Entstehung und das Verhalten neuer Getreidevarietiiten. Archivs fUr Biontologie, igo8. 9© BOTANY OF CROP PLANTS Kraus, C: Die Lagerung der Getreide. Stuttgart, 1908. Knissling, L.: Untersuchungen iiber die Keimung der Getreide. Landw. Jahrb. (Bayern), 1:449-514, 1911. KuDELKA, F.: tjber die Entwicklung und den Bau der Frucht und Samen- schale unserer Cerealien. Landw. Jahrb., 4: 461-478, 1875. HiTiER, H.: Les cereales secondaires. Seigle, Mais, Sarasin, Millet, Rhiz. Paris, 1910. Hoffman: Das Getreidekorn. Berlin, 1912. Hunt, T. F.: The Cereals of America. Orange Judd Co., New York, 1905. NowACKi, A.: Anleitung zum Getreidebau, IV. Berlin, 1905, RiMPAU, W.: Das Bliihen des Getreides. Landw. Jahrb., 1882 (contains the old literature on the blooming of grasses). Untersuchungen iiber die Bestockungen des Getreides. Jahrb. Deut. Landw. Gesell., 1903. ScHiNDLER, Franz: Der Getreidebau. Berlin, 1909. ScHMiD, B.: Bau und Funktionen der Grannen unserer Getreide-arten. Bot. Centralbl., 76, 1898. Schmidt, O.: Uber den Entwicklungverlauf beim Getreide. Ein Beitrag zur Sortenkenntnis. Landw. Jahrb., 45: 267-324, 1913. ScHTJLz, A.: Die Geschichte der kultivierten Getreide, I. Halle, 1913. ScHXJLz, B.: Wurzelatlas. Darstellung naturlicher Wurzelbilder der Halm- friichte in verschiedenen Stadien der Entwickelung. Berlin, 1911. Seelhorst, v.: Versuche iiber die Moglichkeit einer Bewurzelung und Adventivtriebbildung an oberirdischen Knoten von Getreidepflanzen. Jour. Landw., 1902. CHAPTER X TRITICUM (Wheat) Habit of Plant. — Wheat is an annual. Under our cultural conditions, there are two seasonal forms, winter annual, or winter wheat, and summer annual, or spring wheat. Roots. — Wheat has a fibrous root system. In the germina- tion of the grain, the primary root (Fig. 2) takes the lead ; very soon, two secondary roots appear on either side of the primary, thus forming a whorl of three. Later, other roots may be added to these. This whorl constitutes the primary or temporary root system. It usually dies before the plant is fully grown. Permanent roots appear in whorls at the nodes some distance above the three temporary roots. The first whorl of permanent roots is generally about i inch below the soil surface, no matter at what depth the grain was planted (Fig. 3). In their growth, the whorls of permanent roots curve outward and then downward, taking an almost vertical course. They branch very freely near the soil sur- face and form within the first foot a fine network, which constitutes a large absorbing surface. However, many of the roots of wheat reach a depth of 4 feet, or even more under favorable soil conditions. Nobbe observed that the aggre- gate length of all the roots of a one-year-old wheat plant amounts to 500 to 600 meters. The number of roots increases with the number of tillers. Stems. — The stems of wheat are of the general grass type. In wheat, there are usually six joints {internodes) , the sixth being the spike-bearing one. The lowest joint usually re- 91 92 B(^TANY OF CROP PLANTS mains short, sometimes less than i millimeter long; the second joint also remains short; the sixth one is the longest. Leaf. — The wheat leaf is of the ordinary grass type. The blade varies considerably; the sheath is split; the ligule is thin and transparent; the auricles are conspicuous, although not as prominent as those in barley. Inflorescence. — Wheat flowers are arranged in spikelets and the spikelets into a ''head'' or spike (Fig. 38). The spike varies in size, compactness and form in the different types of wheat. Fifteen to twenty fertile spikelets in a head is a fair average, but spikes have been observed with a number considerably greater. An abundance of water in the soil during the early stages of development has been found to increase the number of spikelets in a head. The rachis or main axis of the spikelet is zigzag in shape (Fig. 48). Each joint of the rachis is flattened and curved, the concave surface being on the side next to the spikelet. There is but one spikelet at each joint of the rachis. There are usually numerous short so-called ''basal hairs" at the base of each spikelet. The lower spikelets of the head are often sterile; less frequently, the terminal spikelet is sterile (as in einkorn). Spikelet. — The number of flowers in a wheat spikelet varies from two to five. It has been shown that the number of flowers that reach maturity in a spikelet may be increased by an ample supply of water during the period when the flowers are developing. It is quite probable that there is a "critical period" in the life of the plant at which time the supply of moisture coming to the plant has the maximum effect in the production of flowers. This critical period is probably during the early stages of flower formation, quite a while before the time of heading. The wheat spikelet dissected in Fig. 29 has four flowers, three of which have matured grain. The fourth flower is TRITICUM 93 sterile. In Fig. 28, the lemmas of four flowers are visible. As a rule, but two grains mature. In some varieties, most of the spikelets mature three grains, and less frequently four. The glumes are broad, varying much in shape, color, smoothness or hairiness, width and distinctness of keel, length and sharpness of tip. It has been shown that, in general, the second kernel of a spikelet is the heaviest, the first next heaviest, then the third, fourth, etc. Flower (Fig. 30). — There are three stamens with thread- like filaments and rather large anthers. The single ovary has two feathery stigmas. There are two lodicules. As was pointed out on page . 84, the palet represents the outer perianth whorl, and the lodicules the inner perianth whorl. A.M. Fir,. 32. — Opening of wheat flower. (After Hays.) Opening of Flower and Pollination. — Hays has shown (in a variety of spring wheat) that the flowers open early in the morning, the entire process of pollination taking place within about an hour (Fig. 32). Fruwirth notes that, in warm weather, blooming begins at 4:30 a.m., and continues at a rapid rate until 5:30 a.m. From this latter hour until g:oo 94 BOTANY OF CROP PLANTS a.m., there is less blooming; this is followed l)y a period from 9:00 a.m. to 10:00 a.m. of more rapid blooming, which in turn is followed by an interval of less rapid rate up to 2 :^o p.m.; after this there is an increase in the rate again until 3:30 p.m., and from this hour up to 7:00 p.m., only a slight amount of blooming takes place. Fluctuation in the time of blooming is less noticeable in einkorn than in other wheats, and less marked on sultry days following rainy days in all types of wheat. Polish wheat shows the most marked fluctuations. Temperature and moisture are certainly the important external factors determining the time of blooming. There appears to be considerable variation even in the same variety. It is stated that the swelling of the lodicules brings about the separation of the lemma and palet and hence the open- ing of the flower. Grass flowers in which the lodicules are membranous or wanting remain closed, while those in which there is only slight swelling of the lodicules open but to a small extent. In the unopened wheat flower, the filaments are short, the stigmas erect and in contact. The palet and lemma separate, first slowly and then quickly. The filaments then elongate rapidly, pushing the anthers up and outside of the glumes. The anthers are shedding pollen before the flower is fully open, and they continue to do so until it closes again. All three anthers do not always protrude from the flower, and, in some instances, none may escape before the flower closes. The first flowers to open are those situated about one-third of the way from the tip of the spike. The others follow in succession above and below this point. Each flower remains open from a half hour to one hour. The head^completes its flowering usually in several days. In northern cold or wet climates, close polHnation {auto- TRITinrM 95 gamy) is the rule in nearly all wheats. Durum wheat, how- ever, has the habit of cross-pollination {xenogamy) , and it has been suggested that this behavior is partly responsible for its better adaptation to dry climates, and for its greater dis- ease resistance and vigor. Cross-pollination is quite common in the primitive wheat, which is an inhabitant of a dry, warm country. It appears that cross-pollination is the rule in hot, dry localities, such as certain parts of India. Artificial Cross-pollination.-^One of the chief means of wheat improvement is hybridization. This necessitates the operation of artificial cross-pollination. In this process, the glumes of the flower of the female parent are spread apart and the three stamens removed; this is done just before the anthers are mature. On the same day, or on the follow- ing morning, pollen is taken from the mature anthers of the plant to serve as the male parent, and placed between the glumes of the flower from which the stamens have been re- moved. The chances are that the pollen will reach the stigma branches of the emasculated flower, germinate, and efi'ect cross-fertiUzation. Fertilization and Maturing of Grain.^ — Brenchley states that fertilization in wheat normally occurs between one and two days after pollination. This interval represents the time necessary for the pollen grain to germinate, and for the pollen tube to grow down through the stigma to the embryo sac in the developing ovule. This interval no doubt varies in different varieties and under different environmental con- ditions, particularly temperature. Cool weather will retard germination of the grain, and growth of the pollen tube, and thus affect the "setting" of grain. After fertihzation, the embryo begins to develop, the endo- sperm to store reserve material, and the seed and fruit walls to undergo marked changes. 96 BOTANY OF CROP PLANTS Embryo. — In the very young stage, prior to fertilization, the axis of the ovule is parallel with that of the ovary. Soon in its development, the ovule turns so that its micropyle is directed downward (Fig. 33). At first, the young ovule does not fill the ovary cavity, but soon does so by further growth. The ovule is attached along its side to the ovary. The groove indicates the position and extent of this at- tachment. The first pair of seminal (seed) rootlets appears in the embryo about four weeks after poUination. About a week later, two other rootlets appear above the first pair, and Brenchley describes a fifth lateral rootlet, which does not appear until quite late. Endosperm. — In about a week or ten days after fertihzation, a definite tissue is formed within the embryo sac. This is the endosperm. About seven or eight days later, the aleurone layer is marked off, appearing first on the dorsal side. According to Brenchley, starch first begins to appear in the "flank" cells about the eleventh day after pollination. Eckerson points out that the actual time of the beginning of deposi- tion depends upon the relative activity of the leaves in making sugar and of the embryo in assimilating it. Infiltration of starch is complete in about five weeks after polHnation. It is held that reserve nitrogenous matter enters the endosperm at the same time as the starch. Grain Coats. — Before fertilization, the grain coats are as follows : mi)\e Fig. 33. — Diagram- matic section of young ovary of wheat. {After Bessey.) TRITICUM 97 1. Outer epidermis — one row of cells. 2. Parenchyma layer— m^any rows of colorless cells. 3. Chlorophyll layer— one row of cubical cells, sometimes two, and several in the groove region. 4. Inner epidermis — one row of small cells. 5. Outer integument — two layers. 6. Inner integument — two layers. 7. Niicellus — several layers of thin- walled parenchyma cells, all bounded by a distinct nucellar epidermis. The first four regions listed above constitute the ovary wall (pericarp). After fertilization, marked changes take place in these coats. The nucellar tissue, except its epider- mis, is absorbed by the enlarging embryo. The outer integu- ment (5) and the inner epidermis (4) soon disappear. At hrst, starch is deposited in the entire ovary wall. At the time of resorption of the ovary wall, deposition of starch within it ceases, and its appearance begins in the endosperm. Resorption of the ovary wall begins in the layer just outside the chlorophyll-bearing layer and extends slowly out to the epidermis. Two to four layers next to the epidermis per- sist in the mature grain. The chlorophyll cells become longer, lose their chlorophyll, and thicken their walls. In the proc- ess of maturation, the ovary wall or pericarp becomes firmly attached to the outer layer of the inner integument of the ovule. This behavior seems to be well demonstrated in all grasses investigated. The firm attachment of the peri- carp to the ovule distinguishes the grain or caryopsis from the achene. Ripening Stages. — It is customary to speak of four stages in the ripening of the grain: (i) milk-ripe or green-ripe stage; (2) yellow-ripe, gold-ripe, or "dough" stage; (3) full-ripe stage, and (4) dead-ripe stage. 7 98 BOTANY OF CROP PLANTS In the milk-ripe or green-ripe stage, the embryo is already fully developed. The grain changes from pale green to dark green in color, which change Nowacki explains as being due to the resorption of several layers of the ovary wall, through which the chlorophyll layer now shows. The endosperm cells are filled with a watery sap in which are suspended a number of starch grains; hence, when the grain is squeezed a white, milky juice comes out. In the yellow-ripe, gold-ripe, or "dough" stage, the cells of the ovary wall become thicker. The lumina of inner in- tegument cells decrease in size, due to an increase in the thickness of their walls. The color of the grain changes from green to yellow, and the endosperm becomes tough and waxy. The full-ripe stage follows close upon the preceding. As a result of water loss, the different cell layers become dis- torted. The grain becomes harder and firmer. Grain is usually harvested while in this stage. If the crop is now left in the field, the grain becomes brittle; it is then said to be in the dead-ripe stage. Nowacki gives the following analyses of grains of wheat at different stages of development: Water content of grain Volume of loo grains, cm*. Dry substance in 100 grains, grams Milk-ripe (a) July 9 Milk-ripe {b) July 13 YeUow-ripe July 20 Full-ripe July 23 SI 47 47 69 34 37 25 73 12 91 12 97 S-3I 5-17 5 -07 4.28 3-o8 3-S2 2.86 3.58 4.44 4.19 3-8o 4.22 The maturity of the grain appears to affect its vitality. Kedzie has shown that wheat collected in the dough stage TRITICUM 99 yielded 25 bushels per acre; in the full-ripe stage, 30 bushels per acre, and in the dead-ripe, 28 bushels. The dead-ripe stage produced the most vigorous seed, as was determined by the length to which the plumule would grow. For example, in the above experiment wheat collected in the dough stage produced a plumule 9 inches long, in the full-ripe stage 10. i inches long, and in the dead-ripe stage 1 1 inches long. Similar experiments ^vith rye have shown that plants from immature seeds lack vigor, and also that a large percentage fail to germinate. There is some experimental evidence that by continually planting immature seeds an earlier ripening strain may be obtained. The Mature Grain. — The average weight of 100 kernels of common bread wheat is about 3.866 grams. Durum wheats weigh more per 100 grains. Although the results are con- flicting, there are insufficient positive results to warrant the belief that large plump seeds will give uniformly greater yields than small seeds, especially when such seeds are secured by means of the ordinary fanning mill. It is known that not all the grains in a spikelet are the same size and weight — the second is the heaviest, the first and third about equal in weight, and the fourth and fifth, if present, are lightest of all. It is obvious that all grains from a spikelet regardless of their size, have the same heredity. And a light seed from a spikelet usually will, under similar en\'ironmental condi- tions, develop into a plant with as much vigor as one from a heavy seed from the same spikelet. In the selection of seed wheat, the individual plant should be the basis of selection, when such method is practicable, rather than to depend upon seed from the bin or sack, which is the offspring of many different parent plants. There is a tuft of hairs, the brush (Fig. 34) at the small (stigmatic) end of the grain, and at the opposite end the lOO BOTANY OF CROP PLANTS embryo. Along the side of the grain, facing the palet, is a groove or furrow. This groove marks the region of attach- ment of seed to ovary. The position of the embryo may be seen easily at the base of the grain. Fig. 34 shows a cross- Fig. 34. — Common wheat (Triticum aestivum). A, grain, groove side; B, grain, embryo side; C, cross-section of grain through the embryo; D, cross- section of grain beyond the embryo. pericarp Fig. 35. — Microscopic section of wheat grain. section of a mature grain of wheat through the embryo region. The three primary roots are seen in section. In a cross-section of a mature wheat grain, cut at right angles to its length, so as not to include the embryo, the following layers may be recognized (Fig. 35): TRITICUM lOI T. Ovary wall or pericarp, of several cell layers. 2. Testa, two layers of inner integument. 3. Nuccllus. 4. Aleurone layer, outermost layer of endosperm. 5. Starchy endosperm. Ovary Wall or Pericarp. — The pericarp of the mature grain is composed of several layers of highly compressed cells, the original cavities of which can scarcely be distin- guished. The walls are thickened, cuticularized and ligniiied. The chlorophyll-bearing layer, now colorless, is below these layers. Its cells are marked by numerous narrow trans- verse pits. The outside wall of chlorophyll cells is thin, while the inside wall, next to the integument, is thick. In tan- gential view, chlorophyll-bearing cells appear strongly thickened, rounded at the ends, and closely fitting, thus leaving no intercellular spaces. In rye, these same cells as seen in tangential section are pointed at the ends. The grains of spelt, emmer, and einkorn have the palet and lemma attached, and in these the pericarp is more weakly developed than in the types of wheat with naked grains. In all wheats, the layers of the grain, both fruit and seed, are much thinner at the embryo end than in the other parts of the fruit. It is known that the greatest amount of absorp- tion of water takes place at the embryo end. Testa (episperm) .— It has been noted that, in the develop- ing wheat grain, the testa is composed of two integuments of two layers each. In the ripening process, the outer integu- ment is entirely absorbed, so that in the mature grain the testa consists of two rows of cells, belonging to the inner integument. The walls are slightly ligniiied. The coloring matter of the grain is found in the inner layer of the testa. It is of two kinds, pale yellow and orange I02 BOTANY OF CROP PLANTS yellow. The proportions of these colors determine whether the wheat is white, yellow, or red. Brown found in Triticum, as well as in Avena, Secale, and Hordeum, that the semi-permeabihty of the grain coats is locahzed in the testa. It is very probable that the epidermal membrane of the nucellus also has semi-permeable properties. Nucellus (perisperm). — The epidermis of the nucellus surrounds the aleurone layer. It is the only remaining portion of the nucellar tissue, which was comparatively large in the undeveloped ovule. The mature nucellus consists of cells with strongly thickened walls, and with indistinct cavities. It is possible that in some cases the nucellus is completely absorbed, and hence wanting in the mature grain. Endosperm. — The endosperm consists of two portions, starchy or floury endosperm, and aleurone layer. The endo- sperm constitutes about 92 per cent, of the grain's volume. The cereals are cultivated chiefly for the food material stored in the grain. In all of them, the bulk of this food is found in the endosperm. The chief food materials stored in the endosperm of grains are starch and proteins. The germinating embryo makes use of these foods in the first few days of its growth, or until its roots are taking substances from the soil, and the young leaves are manufacturing food, or, in other words, until the young plant has establishedits independence. Aleurone Layer. — This is a single layer of large cells im- mediately within the nucellus. The cells are rather uni- formly square or rectangular when viewed in transverse or longitudinal section, but irregular in shape when viewed per- pendicular to the surface. They are stored largely with aleurone grains. This layer is often erroneously called the gluten layer. The term "gluten" is only properly applied TRITICUM 103 SO the principal protein found in the starchy endosperm, and thould not be used in connection with the aleurone layer. Starchy Endosperm.- — This is made up of large, somewhat elongated, thin-walled cells. The longer axes of the cells are usually at right angles to the grain surface. They are filled for the most part with starch grains. Protein granules may be seen among the starch grains by appropriate stain- ing. Most, if not all, of the wheat starch and all of the jfarchy enaosperm aleurone- scuiellum-- coleoptile- hyipocotvi - groove ulindr dnc epiblast ^ rooi—- coleorhiza vascular bundle of scuielium point 'of stem Fig. 36. -Part o£ a median lengthwise section of a grain of wheat; much enlarged. (After Slrasburger.) gluten occur in this part of the endosperm. The percentage of gluten increases from the center outward; those cells next to the aleurone layer contain the largest amount. Embryo. — A median lengthwise section of the grain of wheat shows well the structure of the embryo (Fig. 36). The seminal roots point toward the micropylar end. They consist of a primary rootlet with two pairs of laterals. According to Brenchley, a fifth lateral rootlet is foimed in addition to the two pairs usually described. These rootlets are surrounded by the root sheath or coleorhiza. A very short I04 BOTANY OF CROP PLANTS stem, the hypocotyl, is between the primary root and the growing point. In other words, the embryonic stem, or hypocotyl, terminates at the anterior end in a growing point and at the posterior end it is prolonged into the primary root. There are several immature foliage leaves surrounding the growing point and attached to the upper end of the hypo- cotyl. The growing point and foliage leaves are surrounded by a leaf sheath, the coleoptile or pileole. At the point where the root sheath merges into hypocotyledonary tissue, there is a small projection, the epihlast. Lying next to the endo- sperm is a specialized structure, the scutellum, which is attached to the hypocotyl. It has been suggested that the scutellum and epiblast represent two cotyledons, one of which (scutellum) is highly modified, the other (epiblast) suppressed. We are all familiar with the seedlings of bean or squash. In these, there are two cotyledons (seed leaves) which are brought above ground and function for a while as green leaves. Plants with two cotyledons are said to be dicotyledonous. The scutellum of grasses is regarded as a cotyledon, morphologically. Plants like grasses, sedges, rushes, lilies, etc., which have one cotyledon are said to be monocotyledonous . If the epiblast represents a rudimentary second cotyledon, as its position on the embryo would seem to indicate, it stands as evidence of the fact that monocoty- ledonous plants had dicotyledonous ancestry. Rudimentary structures are a great aid in tracing the racial history of all organisms. The scutellum remains in the seed during germination, serving in the absorption of and transfer of food from the endosperm to the growing regions. The outermost layer of the scutellum, where it adjoins the endosperm, is a columnar epithelium. It is probably this layer which secretes TKTTICUM 105 the enzymes through the action of which the starches and proteins in the endosperm are rendered soluble (digested), and which in a soluble form, are enabled to pass from cell to cell to the tissues in the growing points. The embryo is rich in fat or oil, mineral matter and pro- tein, and contains considerable quantities of soluble carbo- hydrates, but probably no or very little starch. About one- sixth of the embryo is fat and one-third protein, the two constituting about one-half of its weight. Bran Layer. — The bran of wheat includes the three outer layers of tissue, viz., pericarp, testa, and nucellus. The pericarp constitutes the larger proportion of the bran and consists largely of mineral and lignified material. The pro- tein content of the bran is due to aleurone cells and starch cells which adhere to bran layers in the milling process. Commercially speaking, bran consists of the scale-like, flaky outside covering which is removed from the wheat in the milling process. It ordinarily contains, in addition to the pericarp, testa, and nucellus, all or part of the aleurone layer and some starchy endosperm which may adhere to it. Wheat bran varies considerably in chemical composition, and hence in feeding value, according to the kind of wheat used and the milling process employed in grinding it. It may contain as low as 14 per cent, and as high as 18 per cent crude protein, with an average of about 16 per cent. Protein of Wheat. — According to analyses of American wheats compiled in 1890, the protein (nitrogen X 6.25) varies from 8.1 per cent, to 17.2 per ceut., with an average of 11.9 per cent. This was in samples containing 10.5 per cent, water, thus making the protein 13.3 per cent, of the dry matter of the grain. Osbourne and Vorhees have recognized the following five wheat proteins: globulin, albumin, proteose, gliadin, and I06 BOTANY OF CROP PLANTS glutenin. The latter two proteins compose gluten. Gliadin is the sticky substance in gluten. As a general rule, grains that have a marked glutenous or horny or flinty appearance are higher in protein than those that have a starchy or dull appearance. However, it is known that a given variety may produce a grain that is hard and rich in gluten; or one that is soft and low in gluten, de- pending on the environmental factors. But it seems true, nevertheless, that the term "quality" refers to both the physical characteristics and chemical composition of the grain. Relative Proportions of the Parts of the Grain. — 1. Bran (pericarp, testa, nucellus), 8 to 9 per cent. 2. Aleurone layer, 3 to 4 per cent. 3. Starchy or floury endosperm, 82 to 86 per cent. 4. Embryo or germ, about 6 per cent. "Hard" and "Soft" Wheats.— A "hard" wheat is one with a horny or flinty texture, and quite high in protein. Hard wheats, as a result of their high gluten content, make a "strong" flour, which is adapted for making light bread. A "soft" wheat is more easily crushed than a hard wheat, has a starchy or dull appearance, and is relatively rich in starch. The "soft" wheats have been regarded with favor for the making of bread and pastry flours. However, the flour from soft wheats is said to be "weak," that is incapable of making a large heavy loaf. At first there was much opposition to hard wheats, because of difficulties in milling and baking. In recent years, however, this opposition has been largely overcome. There are three classes of hard wheats in this country: (i) hard spring wheat, (2) hard winter wheat, and (3) durum wheat. The principal hard spring wheats^are Fife TRITICUM 107 and Bluestem. Turkey and Kharkov are the chief hard winter wheats, and Kubanka the most important durum wheat. On account of its highly glutenous character, durum is used extensively in the manufacture of macaroni and vermicelli. The flour of this hard, glutenous wheat is being mixed with that from the softer wheats, and the result is a flour of excellent bread-making qualities. Much emphasis has been placed upon the great influence of climate upon the composition, hardness and quality of wheat. In fact, it is claimed that the soil has little or no effect upon these characters. In general, a hot, dry climate produces a fine-stemmed plant the grain of which is hard, glassy and rich in nitrogen, while a cool, moist climate pro- duces a coarser-stemmed plant the grain of which is relatively soft, mealy and poor in nitrogen. Headden, however, has been able to produce starchy and flinty kernels at will in the same variety growing under identical climatic conditions, by controlling the ratio of nitrogen to potassium. An abund- ance of nitrates produced a flinty grain, while a scarcity of nitrates in proportion to potash gave a starchy, mealy grain. This work establishes the fact that the soil, as well as the climate, is a factor in determining the quality of wheat. Milling of Wheat. — The wheat is first thoroughly cleaned and scoured to remove sticks, straw, fine dust particles, and hairs of the brush. It is then slightly moistened with water, in order to prevent the pericarp from grinding up fine. This is known as tempering. Then comes the process of breaking. This consists in removing the bran coats and embryo from the endosperm, and the gradual reduction of the latter to finer and finer particles. In this process the grain is passed between successive pairs of corrugated iron rolls. The prod- uct of each set of rolls is sifted, and the particles are graded Io8 BOTANY OF CROP PLANTS according to size, the coarser particles passing on to the next set of rolls. Finally, the pericarp layers are com- pletely separated from the adhering layers of aleurone and starchy endosperm cells. The finely ground parts of the en- dosperm are sifted and bolted. The material that will pass through fine silk bolting cloth is called flour. The larger and coarser particles that remain behind are known as middlings. The middlings are then freed of particles of bran, i.e., purified, and passed between several sets of smooth rolls; the product of each set of rolls is taken to a machine which separates out the fine flour. The number of grades of flour, and of other products, will depend upon the number of sets of rolls, and the mesh of the bolts to which the grain and its ground prod- ucts are subjected. Mills differ much in the grades of material turned out. Kinds of Flour. — There are three general sorts of flour: graham, entire wheat, and patent or straight bread flour. ''Graham flour" is the product obtained by grinding the entire kernel of wheat. Its name is after that of Sylvester Graham (i 794-1 851), a physician and writer on dietetics. "Entire wheat flour" contains about one-half of the coarse bran. In patent grades of flour all of the bran is removed. There are several grades of patent flour, but the most com- mon one on the market is the "straight" or "standard patent." It is usually a combination of the so-called "first patent," "second patent," and "first clear" flours. About 72 to 75 per cent, of the total wheat is recovered as "straight" or "standard patent" flour. It is composed of floury endo- sperm alone. The ordinary bread flours belong to this grade. Other products of the milling process are known as "second clear" flour, used for low-grade bread, "red dog" also used for low-grade bread or for cattle feed, and "shorts, " "middlings" and "bran." About 25 per cent, of the grain TRITICUM 109 is returned as shorts, middlings and bran. The composition of these varies somewhat with the milling process. Germination of Wheat. — The time required for germina- tion depends upon external conditions. The optimum tem- perature for the germination of wheat is close to 84°F., the minimum 40° to 43°F., and the maximum io8°F. Germina- tion will take place under field conditions usually within from four to ten days. Nobbe finds that wheat will begin to germinate in one and three-fourth days at 65°F., two days at 6o°F., three days at 5o°F., and six days at 4o°F. Three germinating stages in wheat are shown in Fig. 2. The primary root is the first to appear. It ruptures the coleorhiza which remains as a collar about the root where it breaks through the grain coats. Very soon two lateral roots appear; hence the primary root system consists of a whorl of three roots. The growing point elongates, the first young leaf being enclosed by the leaf sheath or coleoptile, a closed and pointed organ. The coleoptile protects the growing point and serves as a boring organ. The coleoptile of wheat has the greatest soil-penetrating ability of the common cereals. Its length varies with the variety and with the depth of seeding. The closed end of the coleoptile is broken by the first foliage leaf. The cotyledon (scutellum) is left beneath the ground. Repeated Germination. — The grains of wheat, and the seeds of a number of other agricultural plants, are capable of repeated germination. A grain may start to sprout, the process be stopped by dryness, and sprout again if moisture is available. Beal germinated wheat and buckwheat six times, each time allowing the root and stem to grow to the length of the grain, with the following results : I 10 BOTANY OF CROP PLANTS Repeated Germination Kind of seed Per cent, germinatec I ISt 2d 3d 4th Sth 6th Schumacher wheat Clawson wheat Buckwheat lOO lOO lOO lOO lOO lOO 90 97 100 87 98 98 67 84 6S 8 38 39 Classification of the Types of Wheat.^ — Hackel divides the genus Triticum into two sections, Aegilops and Sitopyros. In the first, the glumes are flat or rounded on the back; in the second, keeled. T. ovata is the principal species in the Aegilops section. It occurs in southern Europe, as far east as Turkestan in Asia. The cultivated wheats belong to the Sitopyros section. Fig. 37. — A, split palet of einkorn (Triticum monococcum) surrounding the grain; B, glume of einkorn; C, glume of club wheat (T. compactum). X 5- Key to Economic Types of Wheat Spikelets two-flowered, one sterile, one fertile; terminal spikelet aborted; lateral teeth of glumes acute (Fig. 37); palet dividing lengthwise when mature. T. monococcum (einkorn). TRITICUM III Spikelets more than two-flowered, two or more fertile; terminal spikelet developed; lateral tSeth of glumes obtuse; palet remaining entire at maturity. Glumes as long or usually longer than lemma; palet about two-thirds as long as lemma. T. polonicum (Polish wheat). Glumes shorter than lemma; palet nearly as long as lemma. Rachis brittle, articulated, breaking at nodes when threshed, the seg- ments remaining attached to spikelets; spikelets two-grained (some- times three in spelt). Spikelets not set thickly on stem; arched on inner side; adhering por- tion of rachis thick, blunt; stem above with central canal. T. spelta (spelt). Spikelets set thickly on stem; flattened on inner side; adhering portion of rachis slender, pointed; stem above, with exception of narrow canal, filled with pith. T. dicoccum (emmer). Rachis tenacious, not articulated, remaining entire in threshing; spikelets usually more than two-grained. Empty glumes sharply and broadly keeled to the base; lemma bearded. Spike with sides parallel or nearly so; glumes with a bloom, usually glabrous; grain very hard, horny, long. T. durum (durum wheat). Spike short, crowded, long-ovate; glumes usually pubescent; grain short, blunt and softer than that of T. dunim. T. liirgidmn (Poulard wheat). Empty glumes keeled in upper half; rounded below (sometimes slightly keeled in lower half) ; lemma sometimes bearded. Spikes very short (rarely over 2 inches); very compact or crowded; thicker at apex than center or base; grains smeill, short. T. compactum (club wheat). Spikes longer than 2 inches, open; sides usually parallel or nearly so. T. astiviim (common bread wheat). The types of wheat fall into two natural groups, as to attachment of lemma and palet to grain, as follows: 1. ^^ Naked wheats,''^ in which the grain comes free from the lemma and palet, and the rachis is tenacious {T. durum, turgidum, compactum, (sstivum, and polonicum) . 2. ''Spelt wheats," in which the grain remains attached to the lemma and palet, and the rachis is fragile {T. mono- coccum, dicoccum, and spelta). 112 BOTANY OF CROP PLANTS Beyerinck has succeeded in producing crosses of einkorn with dicoccum, none of which were fertile* however. Aaron- sohn says that T. polonicum hybridizes with the other species, T. cEstivum and T. monococcum, but the offspring are not fertile. T. monococcum (einkorn) is a small-headed species of no economic impor- tance in this country. It is cultivated to some extent in Spain, Germany, Fig. 38. — Spikes of the types of wheat, i, Polish wheat (Triticum polo- nicum) ; 2, club wheat (T. compactum) ; 3, common bread wheat (T. ffistivum) ; 4, Poulard wheat (T. turgidum) ; 5, durum wheat (T. durum); 6, spelt (T. spelta); 7, emmer (T. dicoccum); 8, einkorn (T. monococcum). and Switzerland. Grains in the ear have been found in the remains near the homes of Swiss lake-dwellers of the Stone Age. It is a native of Asia Minor. Triticum cBgilopoides is considered to be the wild form of our cultivated ein- korn. This wild species is divided into the two subspecies: T. thaotidar and T. boeoticum. In the first, only the lower flower is fertile, as a rule, but both bear awns, while in boeoliciim only the lower flower is fertile and awn^bearing. There is a difference of opinion as to which of these stem forms is nearest to our cultivated einkorn. T. agilopoidcs dififers from cultivated forms of einkorn in that its spikes are more fragile, and the grains smaller and lighter in color. TRITICUM "3 7". polonicum (I'olish wheat) is nol a nali\"o o( Poland, Inil occurs in Jtaly and Abyssinia in Africa. It is cultivated to some extent in this country. T. spella (spelt) is the oldest grain cultivated in Greece, Egypt, and the Roman Empire. It is of slight economic importance in the United States. T. dicoccum (emmer) is of some economic importance in this country, especially in the Western States. T. durum (durum) varieties are also known as "goose," "wild goose," and "macaroni" wheats. They are hard wheats, particularly adapted to the arid regions, where the\' are better yielders than (cstivum wheats. Fig. 39. — Spikelets of the types of wheat, i, einkorn (Triticum monococ- cum); 2, spelt (T. spelta); 3, emmer (T. dicoccum); 4, common bread wheat (T. £Estivum) ; 5, club wheat (T. compactum) ; 6, durum wheat (T. durum) ; 7, Poulard w^heat (T. turgidum); 8, Polish wheat (T. polonicum). About natural size. Durum wheat resembles barley. Its heads are the longest among the wheats. The grains are hard, glassy, often translucent and rather large. T. turgidum (Poulard wheat) is of little consequence in this country. The spikes are quadrangular or rectangular in cross-section. There is a tendency to form branching spikes, as in Alaskan and Seven-headed or Egyptian varieties. Such varieties also go under such common names as Stoner, Miracle, Eldorado, Jerusalem, Many-headed, Many-spiked, Wild Goose, etc. 114 BOTANY OF CROP PLANTS T. compactum (club wheat) varieties are said to be adapted to the Pacific Coast and Rocky Mountain States. In club wheats, the spikes are only two or three times as long as broad, and typically broader at the top than at the base, thus appearing somewhat club-shaped. The joints of the rachis are very short, so that the spikelets are crowded and often stand outright. T. asliviim (common wheat). — ^The bread wheats of the world are largely varieties of cestivum. Origin of Wheat. — A few years ago, Aaronsohn brought from Syria a wild emmer which was named by Koernicke Triticum dicoccum dicoccoides {T. hermonis Cook) (Fig. 40). Later, in an expedition in Upper Gahlee to the north of Lake Tiberias, he found this wild emmer again, and, on Mount Hermon near the village of Arny, he found it very common and in a variety of forms. This was at an altitude of 1,500 to 2,000 meters. Chodat concludes that wheat is indigenous to Syria. He considers that T. dicoccum dicoc- coides, a form with a fragile rachis, is the primitive type of wheat. It is interesting to note that the grains of this "wild wheat" are not inferior in weight or size to those of the best cultivated varieties. It is well agreed that the prototype of our cultivated wheats, whatever it is, is one with a fragile rachis. The rigid rachis is considered to be developed by man. It is known that the wheats cultivated in most ancient times were those with fragile rachises, such as emmer. Furthermore, all genera and species related to wheat, such as Aegilops and Agropyron, etc., have a fragile rachis. The only cultivated wheats of today with brittle rachises are einkorn, emmer, and spelt. It is observed that cross-pollination is more prevalent in Aaronsohn's primitive wheat than in cultivated forms. This may be due to the fact that it grows in a warm, dry climate, while most cultivated wheats belong to northern climates, TRITICUM IIS Fig. 40. — Wild emmer of Palestine (Triticum dicoccum dicoccoides), grown in experimental plat at Bard, California. (Cook, U. S. Deft, of Agr.) ii6 BOTANY OF CROP PLANTS where cold or wet weather prevents flower opemng. In India, it has been observed that cross-poUination in wheat is more frequent than in northern chmates. In the wild wheat of Palestine, the kernels are normally retained by the spikelet. It differs also from domesticated wheat in the order of maturity of the spikelets. In do- mesticated wheat, the first spikelets to de- velop flowers are those near the middle of the head, while in the primitive wheat the terminal spikelets are the first ones. Primi- tive wheat also shows some indications of sexual dimorphism. Some plants have been observed to bear protogynous, others pro- tandrous, flowers. The spikelets of this wild form never mature more than two grains (Fig. 41), and those of the same spikelet are unequal in size. The smaller grain is borne by the lower flower in the spikelet; this flower has the longer awn too. A. Schulz thinks that many, but not all, of the primi- tive wheat individuals found by Aaronsohn are hybrids between T. cegilopoides thaoudar and dicoccoides. The Fig. 41. — Spike- origin of the different types of cultivated wheats, as let of wild emmer given by Schulz, is shown in the following: (Triticum dicoc- ^ Einkom series, of which T. cegilopoides is the cum dicoccoides). X2M2. prototype. 2. Emmer scries, of which T. dicoccoides is the stem form. From this have come dicoccmn, durum, turgidnm, and polonicum. 3. Spelt series, of which the stem form is unknown. From this have come spelta, compactiim, cestivum, and capilatum. Environmental Relations.— Wheat is grown under a wide range of temperature conditions. Some varieties come to maturity and yield well as far as 64° N. latitude in Norway, TRITICUM 1 1 7 and up to 8,000 feet elevation in the Central Rocky Moun- tains. In this last-mentioned section wheat will yield a crop, except in unusual years, where the mean temperature for the year is not below 38°F., and that for the summer season is not below 58°F. Winter wheats are able to resist low tem- peratures for longer periods than spring wheats. Plants differ widely in their water economy. Some re- quire much more water than others to produce a unit of dry matter. The water requirement of a plant is defined as the number of units of water absorbed by the plant in the production of a unit of dry matter. The following data are taken from Briggs and Shantz: Water-requirement Determinations at Akron, Colorado, 1911, 1912, AND 1913, Based on the Production of Dry Matter Plant Mean of genus Proso 293 Millet 310 Sorghum ^ 322 Corn 368 Wheat 513 Barley 534 Buckwheat 578 Oats 597 Rye 685 Beet, sugar 397 Potato 636 Pea, Canada field 788 Alfalfa 831 If the water requirement of proso millet is regarded as i, the water requirement for the following crops is as follows: millet 1.06; sorghum i.io; corn, 1.26; wheat 1.76; barley 1.83; oats 2.04; rye, 2.34; rice, 2.42. The water requirement of a plant is dependent upon a number of conditions, chief of which is the fertility of the soil. The water requirement is greater in an unfertile than Il8 BOTANY OF CROP PLANTS in a fertile soil. The application of fertilizers may increase the total amount of water taken in by the plant, due to increased plant growth, but the requirement per unit of dry matter is lowered. The effect of climate and soil on the composition of the grain has been discussed. Uses of Wheat. — By far the largest proportion of the world's supply of flour is made from wheat-. As already stated, the hard wheats, particularly durum varieties, are used extensively in the manufacture of macaroni and allied products. In the manufacture of macaroni, the wheat is first ground into a course product known as ^^ semolina. ^^ Fig. 42. — Diagram showing the percentage of the world's wheat crop pro- duced by the different countries in 1915. It is freed then of any adhering particles of fine flour and bran. The semolina is mixed with about 30 per cent, of water, worked into a stiff dough, and given a thorough kneeding. The dough is then forced through a press, from which it issues in long hollow tubes. These tubes of moist dough are then carefully dried in a manner to prevent them from becoming too brittle or sour. Vermicelli and spaghetti TRITICUM 119 are also made from semolina and water, but dies of different form are used, and drying is done on frames. Many sorts of breakfast foods are made from wheat. A very recent prod- uct is puffed wheat, in the preparation of which the kernels are expanded by heating to a high temperature under pres- sure, and then the pressure is suddenly released. The whole grain, screenings, bran, shorts, middlings and "red dog" are fed to animals. Sometimes wheat is sown with vetch and the two together used for silage purposes. Wheat, as well as other cereals, finds use in the manufacture of whiskey. It is employed also in the making of weiss-beer malt. Production of Wheat. — The leading wheat-producing countries of the world are shown graphically in Fig. 42. The following table gives the wheat production in the United States for 191 5. Wheat Production in tete United States, 1915 State Acres North Dakota.. . Kansas Minnesota Nebraska South Dakota.. . Illinois Washington Indiana Ohio All other States. 8,350,000 8,525,000 4,310,000 3,947,000 3,725,000 2,800,000 2,000,000 2,750,000 1,980,000 21,511,000 Bushels 151,970,000 106,538,000 73,420,000 72,154,000 60,762,000 53,200,000 50,394,000 47,300,000 40,194,000 352,573,000 United States. 59,898,000 1,011,505,000 Total value dollars 132,214,000 94,819,000 66,678,000 60,609,000 54,835,000 53,200,000 41,324,000 48,246,000 41,802,000 336,575,000 930,302,000 References Aaronsohn, a., and Schweinfurth, G.: Die Auffindung des wilden Em- mers (Triticum dicoccum) in Nord Palastina. Altneuland Monatsschr. fiir die wirtschaftlichc Erschlicssung Palastinas, Berlin, Nos. 7-8, 213- 220, 1906. (0 h z 0) _j ^m ^ I 111 o I- ° Qo o I« O < tiJ Z" o I- o D Q o Q. < U I 5"^ Ii1 1^ i^. Ss?iei)t. Agr. Hur. Plant fnd. Bull. i8o: 36-52, 1910. Bkijerinck, M. W.: Ubcr den Weizenbastard Triticum nionococcum 9? Triticum dicoccum cf. Nederlandsch Kruidkundig Archief., ser. 2, T. 4: 189-201, 1886. Bessey, C. E.: The Structure of the Wheat Grain. Nebr. Agr. Exp. Sta. Bull. 32: 100-114, 1894. Bloomfield, L. M.: Contributions to the Life History of the Wheat Plant (T. vulgare). Ann. Rep. Ohio State Acad. Sci., 2: 12-14, 1894. Brenchley, W. E.: On the Strength and Development of the Grain of Wheat (T. vulgare). Ann. Bot., 23: 11 7-139, 1909. Brenchley, W. E., and Hall, A. D.: The Development of the Grain of Wheat. Jour. Agr. Sci., 3: 195-217, 1909. Chodat, R.: a Grain of Wheat. Pop. Sci. Mo., 82: 33-46, 1913. Cobb, N. A.: Universal Nomenclature of Wheat. N. S. W. Dept. Agr. Misc. Pub. 539, 1905. Cook, O. F.: Wild Wheat in Palestine. U. S. Dept. Agr. Bur. Plant Ind. Bull. 274: 1-56, 1913. DoNDLiNGER, P. T. : The Book of Wheat. Orange Judd Co., 1908. Eriksson, J.: Beitrage zur Systematik des cultivierten Weizens. Landw. Versuchsstat., 45: 37-135, 1894. Fruwirth, C: Das Bliihen von W^eizen und Hafer. Deut. Landw. Presse, 32: 737-739, 747-748, 1905. Hays, Willet M., and Boss, Andrew: Some Botanical Characteristics of Wlieat. Minn. Agr. Exp. Sta. Bull. 62: 391-421, 1899. Headden, W. p.: Yellow-berry in Wheat. Colorado Agr. Exp. Sta. Bull. 205; 1-38, 1915. KoNDO, M.: Studies on Heads of Wheat and Spelt as a Contribution to Exact Classification. Landw. Jahrb., 45: 713-817, 1913. • Krause, Ernst, H. S.: Die Heimat des Spelzes. Naturw. Wchenschr., 25: 412-414, 1910. MoBius, F.: Untersuchungen uber die Sorteneinteilung bei Triticum vul- gare. Inaug. Diss., Giessen, 1913. Druck von F. Stollberg, Merseburg. Osborne, T. B.: The Protein of Wheat Kernel. Carnegie Inst. W'ashington Pub. 84: 1-119, 1907. SCHULZ, August: Abstammung und Heimat des Weizens. 39 Jahrsber. Westfal. Prov. Ver. W%s. u. Kunst (zu MUnster) fiir 1910-1911, S. 147-152, igii- Die Geschichte des Weizens. Ztschr. Naturw., 83: 1-68, 191 1. Die Abstammung des Weizens. Mitt. Naturf. Gesell. Halle, i: 14-17, 1912. Eckerson, Sophia H.. IMicrochemical Studies in the Progressive Develop- ment of the Wheat Plant. Wash. Agr. Exp. Sta. Bull. 139; 1-20, 191 7. J 22 BOTANY OF CROP PLANTS Die Abstammung des Einkorns (T. monococcum L.). Mitt. Naturf. Gesell. Halle, 2: 12-16, 19 13. Triticum aegilopoides Thaoudar X dicoccoides. Mitt. Naturf. Gesell. Halle, 2: 17-20, 1913. ScoFiELD, Carl S.: The Algerian Durum Wheats: A classified list, with descriptions. U. S. Dept. Agr. Bur. Plant Ind. Bull. 7: 1-48, 1902. Ten Eyck, A. M.: The Roots of Plants. Kans. Agr. Exp. Sta. Bull. 127: 199-252, 1904. Thatcher, R. W.: The Progressive Development of the Wheat Kernel. Jour. Amer. Soc. Agron., 5: 203-213, 1913. Woods, Charles, and Merrill, L, H.: Entire Wheat Flour. Me. Agr. Exp. Sta. Bull. 103: 61-80, 1904. CHAPTER XI AVENA (Oats) Habit of Plant. — Oats are annual. The large majority of varieties are summer annuals; a very few are winter annuals. Roots.^ — The root system of oats is very similar to that of wheat. The dense, fibrous growth, which in wheat occurs in about the first foot of soil, is somewhat deeper in oats. The roots of oats extend to a depth of 4 or 5 feet. To quote from Ten Eyck, "Extending down from the center of the root crown of each plant in this example was observed a short rudimentary root stem which ended abruptly with a slight enlargement from which radiated a few short, fine, wire-like roots. Often the old seed coat was found cUnging to the enlarged terminus. The depth at which the seed was planted determined the length of the lower root stem. The explanation of this rudimentary growth is that the seed was planted too deep, or below the point at which soil conditions were most favorable for starting the young roots; hence, the root crown formed considerably above the seed, the lower root stem remaining rudimentary and the Httle rootlets which started from it ceasing to grow early in the season." Stems. — As compared with wheat, the stems of oats are larger in diameter and softer. The number of joints in the culm varies from four to eight. Leaf. — Oats produce abundant leaves. They are broader, as a rule, than those of wheat. The leaf sheath is closed. The ligule is short, oval, and with distinct teeth, thereby differing from wheat, rye, and barley. The young leaves are 123 124 BOTANY OF CROP PLANTS rolled to the left. The auricles are lacking, which also dis- tinguishes it from the other cereals. Inflorescence." — The spikelets of oats are arranged in a panicle. The branching on the main axis is racemose, that Fig. 44. — Diagram of oat inflorescence. (After Broili.) of a higher order is cymose (Fig. 44). The number of whorls in a panicle ranges from four to nine, mostly five or six. Apparently, there are a number of primary branches arising'at a node. However, there is only one primarybranch, AVENA 125 the others being branches of higher order, arising at the base of the primary. The branching decreases from bottom to top. In banner oats {Avena orientalis), the panicle is one- sided. In ordinary panicle or spreading oats {Avena saliva), Fig. 45. — .4, contracted, one-sided panicle of banner oats (Avena orientalis) ; B, spreading inflorescence of panicle oats (Avena sativa). the branches spread toward all sides (Fig. 45). Four main types of panicle oats have been distinguished at the Svalof Experiment Station, as follows: (i) Panicle stiff and upright, (2) panicle pyramidal, the branches long, slender, and rising 126 BOTANY OF CROP PLANTS weakly, (3) panicle widely spreading, (4) panicle with branches weak and drooping. The number of spikelets in a panicle varies, an average number being near 75. The rachis is straight or only slightly undulating. A single spikelet is borne at the end of a slender pedicel, which varies in length. Spikelet and Flower (Fig. 46). — The number of flowers in an oat spikelet varies from two to five, rarely it is one. Three, however, is the usual number. In the so-called ''single ^jtenle 5d flower palet Znd glume— bj glu Fig. 46. — Spikelet of panicle oats (Avena sativa). X 2^- oats," but one flower, the basal, matures. In "twin oats," two flowers mature. Three kernels occasionally mature. The upper flowers of the spikelet are often staminate or imperfect. If a large number of spikelets bear three kernels, there is usually a reduction in the number of spikelets in the panicle, as well as in the total weight of grain froih that panicle. The two empty glumes are unequal, and longer than the lemma. The lemma is rounded on the back, acute, and usually bears an awn which is dorsally attached. As a rule, 'AVENA 127 the lower flower is the only one to bear an awn. The palet is two-toothed, and shorter than the lemma. It fits closely about the grain. Stamens three. Style branches two, plu- mose. Lodicules two, very evident at flowering time. Opening of Flower and Pollination. — The inflorescence opens at the tip first. In oats, as in other paniculate types of inflorescences, there arc a number of cells in the axils of the primary branches which become turgid and bring about the opening of the inflorescence. The first flowers to open in the panicle are in the middle spikelets. The blooming of the entire panicle is completed in six to seven days. In the spikelet, the lower flower opens first, then the second and third in order. The chief blooming time of oats is from 2 :oo to 4:00 p.m. Blooming may continue at slackened speed until 7:00 or 8:00 p.m. A flower usually remains open from fifty to seventy minutes. Hence cross-pollination is not excluded. Self-pollination is the rule, however, due to the fact that all three anthers seldom project from the flower. In cool or rainy weather, flowers may not open at all. Fertilization, and Maturing of Grain. — Oats and wheat are very similar as to fertilization. The oat grain passes through the milk and waxy stages to maturity, as in wheat. After the resorption of the outer integuments, resorption of the parenchyma layer begins. There is a complete resorption of the chlorophyll layer and the inner epidermis. There seems to be a less marked fusion of pericarp and seed coats than in wheat. The Mature Grain. — The kernel is firmly surrounded by the lemma and palet, except in "naked oats." The lemma and palet form the "hull" (Fig. 47). The quahty of oats is judged largely on the basis of per cent, hull and kernel. Hull usually forms from 25 to 33 per cent, of grain weight, but may be as low as 20 per cent, or as high as 45 per cent. 121 BOTANY OF CROP PLANTS The percentage of hull in the upper grains of a spikelet is less than that of lower grains. It is also stated that early- ripening sorts have a greater percentage of hull than late- ripening ones. The reports are conflicting concerning the percentage of hull in short plump grains and in long slender emma — palet -rachilla — lemma -palet 3tarch\j endosperm Fig. 47. — A, mature grain of wild oats (Avena f atua) ; B, mature grain of cultivated panicle oats (Avena sativa); C, grain of same with "hull" removed; Z), cross-section of grain with the "hull." A,BandC, X5; -D, Xio. ones. Furthermore, there is no constant relation between weight of grain per bushel and per cent, of hull. However, if an oat variety is well adapted to a certain region, the per cent, of hull is quite generally lower than if it is poorly adapted. AVENA 129 There are marked differences in the basal and upper grains of a spikelet. The basal grain is the largest and usually bears an awn; the upper ones rarely have awns. A short rachilla (Fig. 47), which bears the second grain, is at the base of the lower kernel. This rachilla varies in length, shape and hairiness in the different oat varieties. The second grain commonly carries no rachilla, or only a fine, thread-like one at the end of which is an immature grain or the mere rem- nants of a third flower. The base of the outer grain is blunt, while that of the inner is pointed. The oat kernel (Fig. 47) is elongated and has a hairy surface. As in wheat, the embryo forms a very small por- tion of the kernel. A cross-section of the grain shows the following coats: (i) lemma; (2) palet, of six to eight cell layers; (3) pericarp, a thin layer of two or three rows of cells; (4) testa, two layers of inner integument; (5) nucellus, one layer; (6) aleurone layer, two rows of cubical cells (some- times one); (7) starchy endosperm. The starchy endosperm of oats, unlike that of wheat, possesses no gluten, and hence it cannot be made into light bread. In this respect it resembles barley. The double row of aleurone cells also distinguishes the oat grain from the wheat grain. The other grain coats and the embryo are very similar. Germination of Oats. — The cardinal temperatures (maxi- mum, optimum and maximum) for oats are about the same as they are for wheat. The young shoot breaks out at the germ end, grows underneath the lemma, and comes out at the brush end. This method of growth is necessitated by the persistence of the palet and lemma. The primary root, however, rup- tures the hull. The coleoptile is closed. The first foliage leaf is rolled. 1,30 BOTANY OF CROP PLANTS Classification of Oats. — The common oat varieties in the United States fall into three species: Avena saliva, A. orientalis, and A. nuda. The latter two are sometimes given as varieties of A . saliva. Avena saliva (panicle oats). — The common oats belong to this species. In these, the panicles are spreading in all directions (Fig. 45). A considerable number of forms are recognized. Four main types, based upon character of panicle,, were given on page 125. As to color of grain, there are white, yellow, gray (winter oats), brown and black sorts. Some are bearded and some are beardless. Avena orientalis (banner, side, mane, or Tatarian oats). — ■ The panicles of these species have erect branches which are close to the main axis (Fig. 45). The inflorescence is one- sided, which character has suggested the common names ascribed to it. There are beardless-white, bearded-white, beardless-yellow, beardless-brown, and bearded-brown varieties. Avena nuda (naked or hull-less oats). — The grains of this oat fall from the hull when threshed. It may be either a spreading or side type. Other Cultivated Oats. — In addition to the three common species of oats given above, the following species are recog- nized and cultivated in various parts of the Old World: Avena slrigosa (rough oats), A. brevis (short oats), A. hyzan- lina (Mediterranean oats) and A . ahyssinica (Abyssinian oats) . Avena fatua ("wild oats").— The so-called "wild oat" is often found in oat fields, and the "seed" may frequently occur as an impurity in farm seed. The plant has slender stems, which are long, and hence it usually stands above the culti- vated oats. It has three flowers to a spikelet, and the awns on the lemmas are strongly bent (Fig. 47), thus differing from common oats. Again, it is distinguished from the AVENA 131 latter by the long reddish-brown hairs at the base of the lemma and on the rachilla. In cultivated sorts, there appears occasionally the so-called "false wild oats," differing in its characteristics both from the cultivated varieties and the true wild oats. It differs from the cultivated varieties in having the long twisted and bent awns. The kernels, however, are similar to those of the cultivated varieties. Origin of Oats. — It is held by Haussknecht, Thellung, Trabut, and others that all the varieties belonging to A. saliva, A. orientalis, and A. nuda have originated from A. fatua. Under cultivation, A. fatua has lost the fragility of its articulations, its hairs and, in some instances, its awns. A. strigosa and A. brevis are derived from A. harhata, a species growing wild in the Mediterranean region, Persia. Mesopotamia, west to Atlantic Europe and Great Britain. A. abyssinica is originated from A. wiestii, a species in- digenous to North Africa and Arabia. A. byzantina has come from A. sterilis, the so-called "animated" or "fly" oats, a wild form frequent in the Mediterranean region. Trabut has found in this region all forms of Avena sterilis ("sterile" oats), beginning with those that are .small and useless and ending with the forms now cultivated there. Algerian oat {A. algeriensis) is the common cultivated variety of the sterile oat. All the forms of oats derived from A. falua are character- ized by the easy separation of the second flower from the rachilla, which persists above the lower flower. In those forms of oats derived from A. slerilis, on the other hand ,the second flower does not separate from the lower flower without carrying away the rachilla at its base. Environmental Relations.— Oats is adapted to a humid, moderately cool climate, such as is found in the region north 132 BOTANY OF CROP PLANTS of the corn belt in the United States. Cool summers favor the ripening of the grain; oats is a better crop than wheat at high latitudes and altitudes. The white and black oats are grown at higher latitudes than red and yellow sorts; the latter are raised in the Southern States, some varieties being sown as winter oats. Practically all of the oats grown in the Northern States is spring-sown. The water requirement of oats is greater than that of any of the other common cereals. It will thrive on soils too wet for corn and in general is better adapted to heavier soils. Uses of Oats.^ — ^Large quantities of oats are consumed annually in the form of rolled oats or oatmeal. The grain is also a much valued horse feed, and not infrequently it is fed to poultry. Oats are sometimes grown for pasture, and also cut before reaching maturity as hay. It makes an ex- cellent nurse crop. Oat straw is used as roughage for stock, and as a bedding. The P*roduction of Oats.^ — As is the case with wheat and corn, the United States also leads all other countries in the production of oats. Russia is a close second. Iowa, Illinois and Minnesota were the leading States in 191 5. Leading Countries in the Production of Oats, Showing Acreage and Production, 1Q15 Countries Acres Bushels United States Russia, European Germany Canada France Austria-Hungary United Kingdom Sweden Argentina * No official statistics. 40,780,000 44,787,000 * 11,365,000 9,051,000 * 4,i4Q,ooo 2,869,000 1,540,362,000 1,006,983,000 650,000,000 481,035,000 234,924,000 234,924,000 195,169,000 70,000,000 62,392,000 AVENA 'I'hk Prodihtion or Oats in the UNiTiiB Statks, iqi.s States Iowa Illinois Minnesota Wisconsin North Dakota... South Dakota.. . Nebraska Ohio Indiana Michigan All other States. Acres 4,950,000 4,343,000 3,125,000 2,150,000 2,450,000 1,725,000 2,200,000 1,683,000 1,638,000 1,530,000 14,986,000 Bushels 198,000,000 195,435,000 134,375,000 99,975,000 98,000,000 72,450,000 70,400,000 69,003,000 65,520,000 64,260,000 472,944,000 Total value, dollars 63,360,000 68,402,000 43,000,000 35,991,000 26,460,000 20,286,000 21,824,000 24,841,000 22,277,000 22,490,000 206,638,000 United States. 40,780,000 1,540,362,000 555,569-000 References Atterberg, a. : Neues System der Hafervarietaten nebst Beschreibung der nordischen Haferformen. Landw. Vers. Stat., 39: 171-204, 1881. BoHMER, C: tjber die Systematik der Hafersorten sowie iiber einige zuch- terisch wichtige Eigenschaften der Haferispe. Berlin, 1909, P. Parey. Hafer im Bilde. Fiihling's Landw. Ztg., 609-616, 1911. Broili, J.: Beitrage zur Hafer Morphologie. Jour. Landw., 58: 205-220, 1910. Hafer im Bilde. Arb. Deut. Landw. Gesell. Heft., 194, Berlin, 191 1. P. Parey. Cannon, W. A.: A Morphological Study of the Flower and Embryo of the Wild Oat, Avena fatua L. Proc. Cal. Acad. Sci. Ser. 3, I, No. 10: 329-364, 1900. Griddle, N.: The So-called White Wild Oats and What They Arc. Ottawa Nat., 23: 127, 1909. Wild Oats and False Wild Oats; Their Nature and Distinctive Charac- ters. Canada Dept. Agr. Bull. 7: i-ii, 1912. Denaifjte and Sirodot: L'avoine, etc. Paris, 1902, 210 figures, pp. 848. Fruwith, C: Die Haferrispe bei der Beurteilung der Sorten und in der Ziichtung. Fiihling's Landw. Ztg., S. 289, 1907. Haselhoff, E.: Vergleichende Untersuchungen deutscher untl amerikanis- cher Hafcrkorner. Landw. Vers. Stat., 65: 339-349, 1907. 134 BOTANY OF CROP PLANTS Haussknecht, E.: iJber die Abstammung des Saathafers. Mitt. Thuring. Bot. Ver. N. F. Heft, 2: 45-49, 1892. Raum, H.: Zur Systematisierung der Hafersorten. Fiihling's Landw. Ztg., 58: 496-501, 1909. RiMPAU, W.: Die genetische Entwicklung der verschiedenen Formen unserer Saatgerste. Landw. Jahrb., 21: 699-702, 1892. ScHULZ, A.: Die Geschichte des Saathafers I und 11. Jalirsber. Westfal. Prov. Vers. Wiss. W. Kunst. Munster.. 41: 204-217, 1913. Abstammung und Heimat des Saathafers. Mitt. Thuring. Bot. Ver. N. F. Weimar., 31: 6-1 1, 1914. Tannert, Paul: Entwickelung und Bau von Bliite und Frucht von Avena sativa L. Inaug. Diss. Zurich, 1905. Thellung, a.: Uber die Abstammung, den systematischen Wert und die Kulturgeschichte der Saathafer-Arten (Avena sativae Coss.) Vrtljschr. Naturf. Gesell. Zurich, 56:293-350, 1911. Trabut, L.: Origin of Cultivated Oats. (Translation) Jour. Hered., 5: 74-85, 1915- Contribution a I'etude de I'origine des avoines cultivees. Compt. Rend., 149: 227-229, 1909. Vierhapper, F.: Zur Systematik der Gattung Avena. Verhandl. K. K. Zool. Bot. Gesell. Wein., 56: 369-370, 1906. Zade: Die Zwischenformen von Flughafer (Avena fatua) und Kulturhafer (Avena sativa). Fiihling's Landw. Ztg., 369-384, 1912. CHAPTER XII HORDEUM (Barley) Habit of Plant, Roots, Stems, Leaves, — Barley is grown as .either a summer or winter annual. It has been observed that two-rowed barley {H. distickon), has a distinct tendency toward the perennial habit like rye. Plants that were mowed down in July sent up new sprouts which de- veloped inflorescences the following September, and after removing these, a third set of sprouts was sent up. It has been suggested that our culti- vated barleys are derived from a perennial form and that in the course of time this habit has been lost. The root system of barley resem- bles that of oats. The culm has from five to seven joints, sometimes eight, the length of which increases from below upward. Barley does not tiller as abundantly as oats and winter wheat. The leaves resemble those of wheat. The auricles, how- ever, are usually very much pro- nounced, and may be used as a basis of distinction between the straws (Fig. 26). Inflorescence.— The inflorescence is a cylindrical spike, the shape of which varies slightly in the different barley 135 Fig. 48. — Rachises of three common cereals. A, barley; B, wheat; C, rye. X 5- 136 BOTANY OF CROP PLANTS types. The rachis is strongly compressed. Opposite each point on the rachis where the spikelets stand, there is a sharply defined horizontal cushion (Fig. 48). This dis- tinguishes the barley rachis from that of wheat and rye. Furthermore, the single joints of the barley rachis are straight, while in wheat and rye they are bent. —lemma Fig. 49. — A, triplet of spikelets of six-rowed barley (Hordeum vulgare hexastichon) ; note that there are three fertile spikelets at the rachis joint; B, triplet of spikelets of two-rowed barley (H. distichon); the two lateral spikelets are sterile; C, single spikelet of hooded barley ( H. vulgare tri- furcatum). At each joint of the rachis, there are three spikelets, each one-flowered (Figs. 49 and 50). The lateral spikelets of each triplet are sometimes imperfect, as in two-rowed barley. Each spikelet is on a short branch or rachilla, which is pro- duced beyond the flower and appears as a bristle (Fig. 51) lying within the groove of the grain. As in wheat, there is HORDEUM 137 no apicaf spikelet in barley. The groups of spikelets arc arranged alternately on the rachis. Spikelet and Flower. — Each spikelet is one-llowcred. The glumes are narrow and awn-like, forming an apparent in- FiG. 50. — I, triplet of spikelets of six-rowed barley (Hordeum vulgare hexastichon) ; 2, of hooded barley (H. vulgare trifurcatum); 3, of medium barley (H. vulgare intermedium); 4, of two-rowed barley (H. distichon). Nat. size. volucre about the spikelets. The lemma is broad, rounded on the back, five-nerved at the apex and bears a long awn with strongly barbed edges. In threshing barley care is taken not to break the awn so close that the end of the kernel 138 BOTANY OF CROP PLANTS is exposed, for by so doing, a point of attack for molds is furnished. The palet is about the same length as the lemma, and bears two ridges. 'J'he styles are short, and the two lodicules are conspicuous and v^ry in the different types. Opening of Flower and Pollination. — The blooming of a spike begins slightly above the middle and pro- ceeds from this point upward and downward. The middle flowers of a triplet come to maturity earlier than the laterals. The duration of blooming varies. Three to four days is a good average for a single spike, and seven to nine days for all spikes of a plant. The glumes of a flower remain open from twenty to thirty minutes. This period depends upon weather conditions. In two-fowed nodding barley, the lateral flowers bloom with open glumes, while the middle ones seldom open. Four-rowed barley almost always blooms with open flowers, both middle and side. In two-rowed erect barley, six-rowed barley and peacock barley, the flowers bloom with closed glumes. It is claimed that, in such cases, the lodicules are too -lemma starchy endospermi Fig. 51. — A, barley grain with the "hull;" B, with "hull" removed; C, grain in cross-section. IIORDEUM 139 weak to force the glumes apart. In four-rowed barley, in which open flowers are the rule, lodicules are well developed. It would seem, then, that in four-rowed barley and two-rowed nodding barley, there is a possi- bility of cross-pollination, while in six-rowed, peacock, and two-rowed erect barleys this possibility is excluded. However, very few positive cases of natural hybridization of barleys have been observed. The reason for this prob- ably is that the styles are short and do not protrude beyond the glumes. Rimpau examined a large number of sorts, and in all, found but eight sure cases of crossing, and these were in four-rowed barleys. Self-pollination is the rule, which means that under field conditions there is little danger that a pure strain will become impure through the introduction of characters brought in by the pollen grains of undesirable strains. Blooming in barley begins between 5:30 and 6:00 a.m., increasing in intensity up to 8:00 a.m. Very little blooming occurs in the middle of the day. There is a slight amount between 3 and 5 o'clock in the afternoon, but by 8 in the evening all blooming has ceased. As in all cereals, blooming is dependent upon the weather. Barleys that normally bloom with open glumes on a day with high temperature and dry atmosphere, may bloom with closed or only slightly open glumes on a cool, moist day. Fertilization and Maturing of Grain. — The immature grain has much the same structure as that of wheat. Kudelka finds that, in barley, the chlorophyll-bearing layer consists of two rows of cells, however. As in wheat, there is an early resorption of the two layers of the outer integument, and of pericarp and nucellar cells. The barley grain passes through the milk-ripe, yellow-ripe, full-ripe, and dead-ripe stages. I40 BOTANY OF CROP PLANTS Mature Grain of Barley. — In hulled barleys, the palet and lemma are firmly attached to the kernel (Fig. 51). In the so-called "naked" or hull-less barley, these scales come loose from the kernel, as in common wheat. The kernel of naked barley resembles that of wheat. It is, however, pointed at both ends (Fig. 51). The kernels are broadest at the middle, in two-rowed barleys, while in the four-rowed types the kernels from the outer rows of the head are slightly twisted and those from the middle rows are broadest near the tip. In the hulled barleys, a rachilla ("basal bristle") persists at the base of the grain on the side adjacent to the palet (Fig. 51). The character of this bristle is of some syste- matic importance. The hull may form from 10 to 25 per cent, of the grain, being greater in^ six-rowed types than in two-rowed types. Variation in percentage of glumes may depend upon season, soil, grain shape, and perhaps fertilizers. Furthermore, Haberlandt has shown that barleys of northern regions have a smaller percentage of hull than those of southern localities. In a cross-section of the mature grain of hulled barley, the following coats are seen: 1. Lemma and palet, five to seven rows of cells. 2. Pericarp, consisting of several rows of parenchyma cells and two rows of chlorophyll-bearing cells. 3. Testa, two layers of inner integument. 4. Nucellus, one row of cells. 5. Aleurone layer, usually of three (two to four) rows of thick- walled cells. 6. Starchy endosperm. As in rye and wheat, the fruit and seed coats are more weakly developed at the embryo end than in other parts of the grain. HORDEUM 141 The embryo of barley is very similar to that of wheat. It occupies but a small part of the grain. Five to eight secondary rootlets occur. The epiblast is absent in the genus Ilordcum. The endosperm varies from mealy to glassy or translucent. Mealiness is the result of a high percentage of starch, while translucency indicates a high percentage of protein. The relative amounts of starch and protein in the different types vary. The two-rowed barleys are used almost exclusively in brewing. There is no gluten in barley grains, and for this reason light bread cannot be made from the flour. Color of Grain.^ — Harlan has made a study of the color of barley grains. He says: "There are two coloring materials in barley: One, anthocyanin, is red in its acid and blue in its alkaline condition; the other, a melanin-like compound, is black. The pigments may occur in the hulls, the peri- carp, the aleurone layer, and occasionally in the starch endo- sperm. The resulting colors of the grain are quite compli- cated. White denotes the absence of all pigment; a heavy deposit of the melanin-like compound in the hulls results in black; a light deposit, brown. Anthocyanin in the hulls re- sults in a light violet-red. In naked forms the melanin- like compound in the pericarp results in a black kernel; anthocyanin produces a violet one. The acid condition of anthocyanin in the pericarp superimposed upon the alkaline condition in the aleurone layer gives the efTect of a purple color, while a blue aleurone beneath a colorless pericarp is blue-gray. White hulls over a blue aleurone cause the grain to appear bluish or bluish gray. Black hulls over a blue aleurone give, of course, a black appearance. The antho- cyanin is always violet in the hulls and in the pericarp, show- ing that these tissues are in an acid condition, and always blue in the aleurone layer, showing an alkaline condition. The 142 BOTANY or CROP PLANTS occurrence of anthocyanin in the pericarp of hull-less barleys is more significant than its production in the aleurone layer." Germination of Barley. — Haberlandt gives the following as the germinating temperatures of barley: optimum 68°F., minimum 37.4° to 39.2°F., maximum 82.4° to 86°F. In brewing, much emphasis is placed upon the ''germinating energy" of the grain. By this is meant its ability to germi- nate within a specified time. A high germinating energy is 96 per cent, in seventy-two hours when kept at 64.4° to 68°F. Much importance is attached to the secretion of enzymes and the conversion of endosperm in the germinating of barley grain. A barley of high diastatic power is preferred; by this is meant the ability to produce an abundance of the starch- dissolving enzyme — diastase. Small grains, with a high nitrogen content have a high power of forming the enzy- matic secretions. The enzymes secreted during germination are chiefly diastase, cytase, and proteases, and it is quite probable that the epithelial layer of the scutellum is the secreting organ. It has been pointed out by Mann and Harlan that "the greatest secreting area for a given grain is secured with a scutellum extending well over the edges of the adjacent endosperm; the greatest vigor in an epithelial layer of long, narrow cells, the highest condition of efficiency in a well-matured, well-cured grain." As has been indicated, the principal enzyme secreted by the germinating embryo is diastase. It has the specific property of changing starch to sugar. Hence, the reserve starch in the embryo, converted to soluble and diffusible sugar, serves to nourish the young plant. Cytase is a cellulose-dissolving enzyme. Protease renders the insoluble proteins soluble. The primary root is the first to appear. This is followed by the secondary ones, and the young shoot. The shoot HORDEUM 143 grows under the lemma and palet to the anterior end of the grain and there l)ecomes free. The coleoptile then opens Jemma / Jodie uU % Fig. 52. — Diagrams showing the relative position of spikelets in barleys. A, six-rowed (Hordeum vulgare hexastichon) ; B, four-rowed barley (H. vul- gare pallidum); C, two-rowed barley (H. distichon); D, medium barley (H. vulgare intermedium). (After Broili.) and the first foHagc leaf appears. In the germination of barley, the young leaves become twisted. This is character- 144 BOTANY OF CROP PLANTS istic of barley. The term " acrospire^^ is sometimes applied to these leaves. The crown roots are formed at a rather constant soil level. If the grain is planted deep, a long internode is formed, such that adventitious roots are produced at the proper level. Classification of Barleys. — There is much difference of opinion concerning the classification of the cultivated barleys. There are at least two distinct species : Hordeum vulgare, in- cluding the six-rowed barleys, and Hordeum distichon, including the two-rowed barleys. Hordeum vulgare hexastichon (six-rowed barley). — It will be recalled that, in the barleys, there are three one-flowered spikelets at each joint of the rachis. In the six-rowed type, every flower of a triplet is fertile. The spikelets are in six distinct rows and stand out equidistant from the rachis. Furthermore, the rows are equal distances from each other about the axis. These points are shown in Fig. 52. The lemmas of all three spikelets are bearded. The rachis inter- nodes are very short, from 2.1 to 2.7 milHmeters long. The kernels from the outer rows are twisted, those from the middle row broadest near the tip, and symmetrical. The "hull" is thick. These are both winter and spring sorts. Six-rowed types are food barleys. Hordeum vulgare (common six-rowed barley) .^ — This is sometimes called a four-rowed barley. Every spikelet is fertile; the lemmas of all spikelets are bearded or hooded; the "hull" is thick; and there is a high percentage of protein. It differs from six-rowed barley in that the rows of grains are not equal distances from each other about the axis (Fig. 52). The lateral grains of one triplet tend to overlap with the lateral grains of the triplet on the opposite side of the rachis. Hence, there will be found often four rows of grains, the central grains of each triplet forming two rows and the HORDEUM 145 overlapping laterals also forming two rows. Furthermore, in four-rowed barley, the rachis internodes are longer (2.8 to 3.5 millimeters) than those in six-rowed barley, and this results in a more loosely arranged spike. A form of four-rowed barley, Hordeum vulgare pallidum, is the common barley in northern Europe, Asia, and America. There are both winter and summer forms. Hordeum vulgare trifurcatum is the four-rowed Nepal barley. In this, the lemmas each have three pronged awns which bend back in the form of small horns or hoods (Fig. 49). It is also often called "hooded barley." There are both naked and hulled hooded barleys. Hordeum vulgare coerulescens is blue barley, H. vulgare nigrum, black barley, and H. vulgare coeleste, the hull-less Jerusalem barley. Hordeum vulgare intermedium (medium or hybrid barley) .- — Under this name are included those barleys that are transition forms between the two- and many-rowed types (Fig. 52). In these intermediate forms, only the two middle rows are nor- mally formed, the four lateral ones being beardless and smaller. It is quite probable that the intermedium forms are segregates of the hybrids of certain two-rowed and many-rowed forms. Hordeum distichon (two-rowed barley). — In this, the spikes bear two longitudinal rows of grains. As in six-rowed barley, the spikelets occur in groups of three on opposite sides of the rachis, but in the case of two-rowed barley, the lateral spikelets of each triplet do not mature, only the middle one of each maturing its grain (Figs. 49 and 52). However, the glumes of the lateral spikelets develop normally. The anthers of side spikelets may be either dwarfed or well developed. The kernels of two-rowed barleys are symmet- rical and broadest in the middle. The hull is thin. There is a low percentage of protein and a mealy endosperm. There are four rather common types of two-rowed barleys: 146 BOTANY OF CROP PLANTS I . Honlcum dislichon zeocrilon (peacock or fan barley) (Fig. 53). — The spikes are very dense and short, about 6 Fig. 53. — Spikes of barleys, i, two-rowed nodding barley (Hordeum dis- tichon nutans); 2, medium barley (H. vulgare intermedium); 3, four-rowed barley (H. vulgare pallidum); 4, hooded barley (H. vulgare trifurcatum) ; 5, six-rowed barley (H. vulgare hexastichon). centimeters long, broad at the base and narrow at the tip, and with widely spreading beards. 2. Hordeum distichon nudum (two-rowed naked barley). HORDEUM 147 ,•5. llordcinii (lislichoii crcclum fcroct-carcd barley). -In this the heads are erect and broad. On the dorsal side of the grain at the base, there is a characteristic crown furrow, so that in longitudinal section a rounded hump shows (Fig. 54). Rachis joints are from 2.1 to 2.7 millimeters long. The rachilla is hairy and broadened. Fig. 54. — Bases of the grains of two-rowed barleys. A, B, nodding barley (Hordeum distichon nutans); C, D, erect-eared barley (H. distichon erec- tum). (After Newman.) 4. Hordeum distichon nutans (bent or nodding barley). — In this the heads hang down when ripe. On the dorsal side of the grain at the base, there is a slight horseshoe-shaped depression. In lengthwise section, the base of the kernel slopes off (Fig. 54). Rachis joints are 2.8 to 3.5 millimeters 148 BOTANY OF CROP PLANTS long. The rachilla is broom-form or very hairy. The noted malt barley. Chevalier, belongs to this type. Origin of Cultivated Barleys. — There are two principal opinions regarding the origin of cultivated barley, that of Koernicke and that of Rimpau. Koernicke considers Hor- deum spontaneum to be the prototype of all our cultural forms. This wild barley is nearest related to the nutans form of two-rowed barley, being distinguished from the latter by its more fragile rachis, less compressed spike, stronger awns, larger side spikelets, perennial habit, and its stronger tendency to tiller. The variety ?iutans first arose from the wild form. From this came erectum, by a shorten- ing of the rachis joints. From crcctum, came zeocriion by still greater shortening of rachis joints, and an enlargement of the fruit toward the base. From nutans also, there arose the four-rowed barley, by the side spikelets becoming fertile. From erectum and zeocriton, there came six-rowed barleys. Rimpau, on the other hand, considers the six-rowed bearded barley as the prototype of all other barley types. Through a process in which side spikelets become rudimen- tary, there arose the various four- and two-rowed types. Rimpau bases his opinion on the nature of the offspring between zeocriton and trifurcatiim. Environmental Relations. — Winter barleys are less resist- ant to winter cold than either winter wheat or winter rye. Consequently, in the Northern States practically all barley is spring-sown. As a spring-sown crop it has a wide geo- graphical range. It is grown as far as 65° N. latitude in Alaska, and to an altitude of 7,500 feet in the Rocky Moun- tains. At higher elevations it is grown as a hay, the chief variety being *'bald barley." Barley also does well in southern California. HORDEUM 149 Barley stands between oats and wheat in its water recjuirement. Uses of Barley. -Barley has a great variety of uses. Its greatest use is in the preparation of malt. The two-rowed barleys have larger and softer grains than six-rowed barleys and therefore are preferred for malting purposes. Smaller quantities are ground into fiour from which bread is made. " Pearl barley" (grains with the lemma and palet removed) is used for soups. Barley enters into a few cereal breakfast foods. It is a. valuable stock feed, especially for hogs, sheep, dairy cows, and poultry. The six-rowed barleys are regarded as valuable sorts for feeding. The hooded varieties, chiefly, are grown as hay. Barley is sometimes grown as a pasture crop, as a nurse crop and as a smother crop. A pasture crop is used for grazing. A nurse crop is a temporary one often planted with a forage plant such as clover or alfalfa in order to secure a greater return from the land the first year, also to inhibit weed growth, and to prevent the blowing or washing of the soil. A smother crop is used to prevent the growth of weeds. The straw of barley is fed, and also serves as a bed- ding for stock. Malt sprouts and "brewers' grains " are now and then utilized as stock food. The Brewing Process.^ — Brewing operations vary con- siderably in the different countries, and with the character of the product. The brewing materials employed are malt, hops and water. The malt is made from germinating barley, and to this are sometimes added unmalted cereals such as corn, wheat and rice. Malting. — In this process, barley is prepared for brewing purposes. The barley grains are steeped for about fort}- eight hours in water, and then spread out on the malting floor. The temperature of the air in the malting room is L^cween 50 and 6o°F. Germination is not allowed to pro- 150 BOTANY OF CROP PLANTS ceed to the point when the young shoot (acrospire) breaks out from under the lemma and palet, but the process is checked by transferring the germinating grain to a kiln where it is kept for about twelve hours at a temperature sufficient to thoroughly dry it out. During germination, there is secreted from the epithelial layer of the scutellum a diastase which converts the starch to maltose sugar. Pep- tase is also secreted by the germinating barley; this enzyme modifies the albuminoids of the malt. Mashing. — The malt, prepared as above, is cleaned, and crushed in a roller mill. It is then mixed with water, and in some cases with unmalted cereals. The mash is then held at the proper temperature for the action of diastase and pep- tase, which chemically invert the starch into maltose, malto- dextrin and dextrin, and change the insoluble albuminoids to a soluble form. Boiling the Wort. — The product of the mashing machine is called "wort." During the boiling process, hops are added. Boiling serves not only to extract desirable products from the hops, but to render harmless certain undesirable con- stituents. After boiling, the wort is strained into coolers. Fermentation. — Yeast is now added to the wort. This introduction of yeast is called "pitching." Through the activity of yeast, the sugar in the wort is changed to alcohol and carbon dioxide. The wort has been changed to beer. It is removed from the fermenting vat, stored for a period to allow certain products to settle, and also to permit of after- fermentation, and then clarified, filtered, and packed for the market. Production of Barley. — The four leading countries, in 1915, in the production of barley were: Russia, United States, Germany, and Austria-Hungary, producing respec- tively 475,109,000; 277,009,000; 150,000,000; and 136,186,000 bushels. HORDEUM 151 Acreage, Production and Farm Value of Barley in Various States, 1915 States North Dakota... Minnesota California ...... South Dakota.. . Wisconsin Iowa Kansas All other States. United States . . . Acres 1,400,000 1,350,000 1,360,000 750,000 656,000 353,000 270,000 1,256,000 Bushels 44,800,000 41,175,000 39,440,000 24,000,000 23,288,000 10,943,000 8,370,000 44,993,000 Farm value, Dec. I, dollars 19,712,000 20,176,000 24,453,000 11,040,000 13,041,000 5,362,000 3,515,000 25,200,000 7,395,000 237,009,000 122,499,000 References Atterberg, a.: Die Erkennung der Haupt-varietaten der Gerste in den Nordeuropaischen Saat- und Malzgerstan. Landw. Versuchstat., 36: 23-27, 1889. Die Varietaten und Formen der Gerste. Jour. Landw., 47: 1-44, 1899. Brenchley, Winifred E.: Development of the Grain of Barley. Ann. Bot., 26: 903-928, 191 2. Broili, J.: tJber die Unterscheidung der zweizeiligcn Gerste-IIordeum distichum-am Korne. Tnaug. Diss. ■Uni\^ Jena, 1906. Das Gernstenkorn im Bilde. Stuttgart, 1908. Brown, H. T., and Ksco>rBE, F.: On the Depletion of the Endosperm of Hordeum Vulgare during Germination. Proc. Roy. Soc. (London), 63: 3-25, 1898. Fruwirth, C: Das Bliihen der Gerste. Fiihling's Landw. Ztg., S. 544, 1906 Harlan, Harry V.: Some Distinctions in Our Cultivated Barleys, with Reference to Their Use in Plant Breeding. U. S. Dept. Agr. Bull. 137, 1-38, 1914. Henning, E.: Beobachtungen iiber das Bluhen der Gerste (Schwedisch). Bot. Notiser., 1905. Hummel, A.: Die botanischen Unterscheidungsmerkmale bei zweizeihger Gerste. Illus. Landw. Ztg., 830-839, 1909. Johannsen, W.: Entwickelung und Konstitution des Endosperms der Gerste. Ztschr. Gesam. Brauw., 1905. Kraus, C: Die Gliederung des Gersten- und Hafcrhalmes und deren Bezie- hungen zu den Fruchtstanden. Bcilieft I der Naturwis. Ztsch. fiir Land- und Forstwirtlisrliafl. Munchen, 1905. 152 . BOTANY OF CROP PLANTS Mann, Albert, and Harlan, H. V.: Morphology of the Barley Grain with Reference to its Enzyme-secreting Areas. U. S. Dept. Agr. Bull. 183: 1-32, 1915. QuANTE, Hugo: Die Gerste, ihre botanischen unci brautechnischen Eigen- schaften und ihre Anbau. Berlin, 1913. RiMPAU, W. : Die genetische Entwicklung der verschiedenen Formen unserer Saatgerste. Landw. Jahrb., 21: 699-702, 1892. ScHULZ, A.: Die Geschichte der Saatgerste. Ztschr. Naturw., 83: 197-233, 1912. Die Abstammung der Saatgerste, Hordeum sativum l-II. Mott. Naturf. Gesell. Halle, i: 18-27, 1912. TscHERMAK, E.: Die BlUh- und Fruchtbarkeitsverhaltnisse bei Roggen und Gerste und das Auftreten von Mutterkorn. Fiihling's Landw. Ztg., S. 194, 1906. Voss, A.: Versuch einer neuen Systematik der Saatgerste. Jour. Landw., SS: 271-282, 1885. ZoBL, A., and Mikosch, C: Die Funktion der Grannen der Gerstenahre, Zitzber. Akad. Wiss. (Vienna) Math. Naturw. Kl., loi: Abt. i, 1033- 1060, 1892. CHAPTER XTII SECALE CEREALE (Rye) Habit of Plant, Roots.^ — Rye is an annual. It is reported, however, that rye stubble in a field may sprout after long standing, or that close pasturing for a season may cause it to live through a second winter. This is no doubt a reversion to the perennial habit displayed by the species from which our cultivated rye came. Rye throws out a whorl of four primary roots, thus differ- ing from the other cereals. The root system branches pro- fusely in the first foot of soil and extends to a depth of 4 or 5 feet. Stems, Leaves. — As compared with wheat, oats and barley, the stems of rye are tougher, slenderer, and longer. There are commonly five to six, rarely four to seven stem joints. The leaves are similar to those of wheat. The ligule is short and somewhat rounded. The auricles are white, narrow and wither early; sometimes they are absent altogether. Inflorescence.- — This is a spike. It is usually somewhat longer than the wheat spike, and is rather uniformly four- rowed. There are from 20 to 30 rachis joints. There is a single spikelet at each joint. All the spikelets, from base to tip, are fertile. The spikes have no terminal spikelet. Spikelet. — Each spikelet (Fig. 55) consists of three flowers. The two lateral flowers mature grains, the middle one aborts. The glumes are very narrow; the lemma is broad, keeled, and bears a long, terminal awn ; the keel is strongly barbed ; the palet is thin, blunt and two-keeled. The lodicules- are 153 154 BOTANY OF CROP PLANTS small, membranous, and ciliate on the upper margins. There are three stamens, and a single pistil with two feathery stigmas. Opening of the Flower, Pollination and Fertilization.— Rye is the only common cereal, besides corn, that is regularly cross-fertilized. These twb cereals cannot be self-fertihzed without a reduction in vigor and productivity. Apparently, Fig. 55. — Rye (Secale cereale). A, a single spikelet at a joint on the rachis; B, grain, external view; C, grain in cross-section. A, X 2}i; B and C, XS- no ill effects result from self-fertilization of barley, wheat and oats. According to some observers, the pollen of rye is im- potent on the stigma of the same flower. Fruwirth notes that the flower is completely closed within twenty-five to thirty minutes after it begins to open, providing the stigmas re- ceive pollen. In case the stigmas are not dusted, the flowers remain open much longer. Blooming begins between 5:00 and 6 :00 a.m. and continues until qiooor 11 :00 a.m. Then blooming decreases throughout the afternoon, becoming SECALE CEREALE I 55 more rapid again in the evening. The first flowers to open are slightly above the middle of the spike. It has been ob- served that the flowers of rye can be induced to open by rubbing with the hand, or by other mechanical stimulation. Maturing of Grain, and Mature Grain.^ — The anatomical structure of the ovary at blooming time is similar to that of wheat, as are also the changes which take place in the grain during its ripening. The mature grain (Fig. 55) is free from the lemma and palet. It is long, narrow, and usually darker in color than wheat. The cross-section of the mature grain shows layers similar to those in wheat, although different from it in details. Rye protein usually forms about 6 to 12 per cent, of the grain. Gluten is present in the protein, hence, the flour may be made into porous bread. It will be recalled at this point that of the common small cereals, wheat and rye possess glu- ten, while oats and barley do not. The flour from rye is more starchy than that from wheat. Germination of Rye. — Under favorable conditions, germi- nation will take i)lace in thirty-six to forty-eight hours. The optimum germinating temperature is 77°F., maximum Sy^F., and minimum 33.8°F., to 35.6°F. By deep seeding, rye may send out roots and tillers at the second, third, or even fourth node. As a result rye can be planted deeper than wheat. The coleoptile is closed; the first leaf is rolled and brownish-red, which color distinguishes the rye seedling from other cereals. Classification, and Origin of Rye. — The cultivated sorts of rye all belong to the one species, Secale cereale. This origi- nated from Sccalc anatolicum, one of the subspecies of S. monlanum. This stem form differs from S. cereale in the fragile rachis, the smaller, narrower fruit, and perennial rootstock. Environmental Relations. — Rye is adapted to colder and 156 BOTANY OF CROP PLANTS drier climates than wheat, and will thrive on poorer soils and more sandy soils than any of the other cereals. Uses of Rye. — Rye flour is made into bread. A few break- fast foods include rye as a minor component. Mixed with barley, or corn, or shorts, or oats, rye grain is fed to stock. In some sections it is grown for hay, or as a pasture crop, and now and then as green manure. The straw finds consider- able use as a stable bedding, as a packing material for nursery stock, as a stuffing for horse collars, and it is also used in the manufacture of paper, strawboard, hats, and other coarse straw articles. Production of Rye. — Russia produced 861,097,000 bushels of rye in 191 5; Germany ranked second, with 470,000,000 bushels, Austria-Hungary third, with 154,075,000 bushels, and the United States fourth, with 49,190,000 bushels. The five leading States in the order of their production for the year 191 5 are Wisconsin, Michigan, Minnesota, Pennsyl- vania, and Nebraska. References Batalin, a.: Das Perennieren des Roggens. Acta. Horti. Petropolitani, 11:299-303, 1890. Also Verhandl. Bot. Ver. Brand., 32:29-32, 1891. RiMPAU, W.: Die Selbst Sterilitat des Roggens. Landw. Jahrb., 6, 1877. ScHULZ, August.: Die Geschichte des Roggens. Jahresbericht des West- falischen Provinzial-Vereins fiir Wissenschaft und Kunst (zu Munster) fur 1910-1911, 39:153-163, 1911. Beitrage zur Kenntnis der kultivierten Getreide und ihrer Geschichte, I. Die Abstammung des Roggens. Zeitschr. Naturw., 84:339-347, 1913. TscHERMAK, E.: tjber kUnstliche Auslosung des Bliihen beim Roggen. Ber. Deut. Bot. Gesell., 22:445-449, 1904. Das Bliihen des Roggens (Secale cereale). Ostrk. Landw. Wchnbl., 1906, p. 163. Die Bliih- und Fruchtbarkeitverhaltnisse bei Roggen und Gerste und das Auftreten von Mutterhorn. Fuhlings Landw. Ztg., 55:194-199, 1906. Ulrich, C.: Die Bestaubung und Befruchtung des Roggens. Inaug. Diss., Jena, 1902. WiTTMACK, L.: tjber die Stammpflanze des gemeinen Roggens, Secale cereale. Verhandl. Bot. Ver. Brand., 32:32-34, 1890. CHAPTER XIV ZEA (Com, Maize) Habit of Plant, Roots. — Corn is distinctly a summer annual. The root system is fibrous. Corn generally has been con- sidered a shallow-rooted plant. The contrary is the case. At maturity the roots come to fill the upper 3 feet of soil and, under some conditions, may reach to a depth of 4 or 5 feet (Fig. 56). The depth of planting appears to bear no rela- tion to the depth of rooting, for the first whorl of roots usu- ally forms about i inch below the soil surface, no matter how deep the seed is planted. It will be remembered that this is true for the other cereals too. The roots of corn are thrown off in whorls, varying in number from two to ten, one whorl above another. The internodes between whorls are very short. The entire group of whorls constitutes the root crown. Two kinds of roots are developed (Ten Eyck) : [a) main vertical roots and {h) main lateral roots. Vertical roots curve out slightly from the crown and go directly downward. The laterals curve downward, as they leave the crown, then extend horizontally for a distance, finally taking a downward course. Laterals that leave the crown at about the soil level slope gradually downward, as indicated above. Midway between the rows of planted grain, about 22 inches from the 157 iS8 BOTANY OF CROP PLANTS hill, these laterals are about 4 or 5 inches below the soil level. The laterals may be shallower than given, in heavy soils dround line I Ground line Fig. 56. — A , root system of corn (Zea mays) ; the squares are one foot on a side; B, prop or aerial roots of corn. {A, redrawn from U. S. Dept. Agri.; B, somewhat modified after Bailey.) and wet seasons. The roots of most plants are more super- ficial in a heavy or wet soil than in a light and drier soil. ZEA 159 • This is quite likely a response to oxygen supply, as well as to moisture supply. The amount of oxygen in the soil decreases as the depth increases. Moreover, the rate of decrease is greater in heavy or wet soils than in light or dry soils. When it is understood that every living root cell derives its oxygen for respiration from the soil air immediately surrounding and that the oxygen does not diffuse to any extent from the aerial parts of the plant down through the stem to the roots, we see the probable explanation of the fact that a shallow root system is peculiar to a heavy or wet soil. In this con- nection, it should be stated thatanimportant result of tillage is the loosening of the soil so that oxygen may more easily diffuse to the roots of the plant. All main roots give off numerous finer branches and these in turn branch, so that at maturity there is an interlacing mass of roots in the soil. Fully two-thirds of the entire root system occurs in the first 4 inches of soil. This statement is based on records of a number of observers (Sturtevant, Hunt, Newman, Ten Eyck, Hays). Ten Eyck has observed that, although the main laterals are several inches below the soil surface, they may send upward finer branches to within Yi inch of the sur- face. The depth of the corn roots determines the depth of cultivation. If it is so deep as to destroy roots, the yield is decreased. "Prop" or "Brace" Roots. — In addition to the ordinary underground roots, corn develops aerial roots, the so-called ''prop'' or ''brace" roots (Fig. 56). These arise in whorls at successive levels above the surface, extending obliquely downward. They are covered" with a mucilaginous sub- stance which protects them from drying out. As aerial roots, they are unbranched, but they branch profusely when they strike the soil. They have the role of absorption, then, as well as anchorage. l6o BOTANY OF CROP PLANTS Stem. — Corn is the largest of the common cereals. How- ever, no other cereal varies so in size. There are dwarf forms scarcely 3 feet high, while some are 15 or more feet high. The stem is jointed as in all grasses. The internodes, how- ever, are not hollow, but are filled with a soft pith through which run numerous vascular bundles, the fibers. The nodes are solid as in other grasses. The internodes are furrowed on the side next the leaf blade. The corn plant produces ''suckers^'' which correspond to the "stools" of wheat, as to their morphology. "Suckers" are secondary stems or branches arising from the lower nodes. These branches develop their own roots. "Suckers" of corn are undesirable, for they do not, as a rule, produce ears, although they are heavy soil "feeders." Leaves.^ — The leaves are arranged alternately on opposite sides of the stem as in all grasses. They vary in number from 8 to 20. The blade is long and flat; the ligule closely invests the stalk, acting as a rain-guard. Water that runs down the stem and leaf blade is prevented from entering the space between 'the culm and leaf sheath by this tightly fitting ligule. The corn leaf is thrown into a number of folds along the edges and at the base. This is due to the more rapid growth of the cells at these points. The corn plant is moderately well adapted to dry conditions. An examination of the leaf structure explains this. On the upper surface of the leaf blade, along either side of the midrib, are a number of large wedge-shaped cells; these absorb water readily in moist weather, become turgid, and thus flatten the leaf out. In dry weather, these cells lose their turgor. Hence the leaf rolls up, presenting a smaller evaporating surface. In addi- tion to this adaptation to dry conditions, the cuticle of the lower surface of the leaf is much thickened, and the water ZEA l6l requirement of the plant is low as compared with 'oats, clover, or alfalfa. It has been computed that an average acre of well-adapted corn, grown at the Nebraska Agricul- FiG. 57. — Pistillate and staminate inflorescences of corn (Zea mays). tural Experiment Station, has 4 acres of leaf space, counting both sides. Inflorescence.^ — Ordinarily, corn is monoecious, that is, l62 BOTANY OF CROP PLANTS the stamens and pistils are borne in separate inflorescences on the same plant (Fig. 57). The staminate flowers are in a panicle at the top of the stalk; this inflorescence is known as the ^' tasselJ^ The pistillate flowers are borne in a spike which is placed in the axil of a leaf lower down on the stem. When mature, the pistillate inflorescence is called the ''ear." Staminate Inflorescence (" tassel") .^ — The rachises of the panicle are long, slender, and spike-like. One may distinguish between the central and lateral spikes of the panicle. In the central spike (Fig. 58), there are usually from four to eleven rows of spikelets, in pairs. Lateral branches usually have only two rows of spikelets, in pairs. One spikelet of each pair is pedicellate, the other sessile (Fig. 59), or in some cases both may be sessile. The groups of spikelets may overlap. Staminate Spikelet.^ — Each normal stami- nate spikelet bears two flowers, each produc- ing three perfect stamens and a rudimentary pistil (Fig. 60). The glumes are seven- to twelve-nerved, and about equal in size. The lemma is three- to five-nerved and the palet two-nerved. The two lodicules are fleshy and truncate. The anthers are long. The upper flower of a spikelet matures first; its palet is larger than the lemma, while in the lower flower, the lemma is larger than the palet. Pistillate Inflorescence ("ear") General Characteristics. — The ear (Fig. 61) is borne on a short Fig. 58 . — A single branch of the staminate in- florescence of corn (Zea mays). ZEA 163 branch, the so-called "shank." This branch consists of a number of very short internodes with one modified leaf at each node. The blades of the modified leaves have been JeJJile spikelet lemmas -flumes pedicellate 'spikelet Fig. 59. — A'pair of staminate spikelets of corn (Zea mays). reduced, the leaf sheaths alone remaining. The collection of leaf sheaths on the shank forms the "husk" of the ear. The pistillate spikelets are arranged in rows along a fleshy axis, the "cob." 164 BOTANY OF CROP PLANTS --An What Is the "Ear,'' Morphologically? — There are two theories as to the morphology of the ear of corn. The view of Hackel and of Harshberger is that the ear is the result of a fusion of a number of two-rowed pistillate spikes. Since each spikelet is two-flowered, and the lower abortive, there are often formed the two distinctly paired rows. The cob is said to be formed by the fusion of separate rachises. Opposed to the above theory is that of Montgomery, who holds that the ear develops "directly from the central spike of some tassel-like structure similar to the well-known corn tassel." His evidence for this belief may be summarized as follows: 1. He has found tassels in which a few pistillate flowers were found on the central spike, also tassels in which the central spike had developed into a fair- sized ear of corn. 2. He observed a case in which the lateral spikes as well as the central one had developed pistillate flowers, form- ing a number of four-rowed "nubbins" surrounding a central well-developed twelve-rowed ear. 3. The central spike develops pistil- late flowers much more readily than the lateral ones of the tassel. The central spike has the greater number of rows of spikelets. 4. He has observed the development of pistillate flowers from staminate ones. This development is as follows: Fig. 60. — Longitudinal section of staminate spikelet of Country Gen- tleman sweet corn, X 1 5. G, glume; Pa, palet; An, position of one of the lateral anthers; L, lem- ma; A, dorsal anther. P, rudimentary pistil; J, joint of rachilla. (After Weatherwax.) ZEA 165 (a) Pedicellate spikelet shortens and becomes sessile; the difference between the two flowers of this becomes greater. (b) The lower glume shortens and thickens. Fig. 61. — Corn (Zeamays). Young pistillate inflorescence ("car"), showing the long styles ("silks"). (c) Lemma and palet of upper flower become reduced while the lower flower becomes abortive. (d) Sessile flower becomes pistillate. (e) Both flowers become pistillate. i66 BOTANY OF CROP PLANTS Recently East and Hayes have expressed an opinion very similar to that of Montgomery. Quoting from them, "The ear of maize, then, is a meristic variation produced from the central spike of the tassel of the lateral branches of teosinte or of a teosinte-like plant, and not a fusion of the lateral spikelets." Montgomery suggests that teosinte and corn had a common ancestor, which was a "large, much-branched grass, each branch being terminated by a tassel-Hke structure. M ^lume palef, of ' jlower -lemma of fertile ' flower •Znd ^lume Fig. 62. — Pistillate spikelet of corn, much enlarged. (After Nees.) bearing hermaphrodite flowers." He says further: "As evolution progressed, the central tassel came to produce only staminate flowers, these being higher and in a better position to fertihze the flowers on the lower branches. At the same time, the lateral branches came to produce only pistillate flowers, their position not being favorable as pollen producers, while, on the contrary, they were favorably placed to receive pollen. This dift'erentiation in the flowers was accompanied by a shortening of the internodes of the lateral branches until they were entirely enclosed in the leaf sheaths" (the husks). Pistillate Spikelet. — Each normal pistillate spikelet has two ZEA 167 flowers, the lower one of which is abortive^ (Figs. 62 and 63). The palet and lemma of the abortive flower remain, and form a part of the "chaff" on the cob. The spikelet is subtended Fig. 63. — Longitudinal section of pistillate spikelet of Black Mexican sweet corn, X 25. Sli, base of stigma; Sly, style; £, outline of embryo sac; L, lemma; Pa, palet; St, stamen of aborted flower; 5c, stylar canal; Ov, func- tional ovule; G, glume; Sta, rudimentary stamen; P, pistil of aborted flower; J, joint of rachilla. {After Weatherwax.) by two glumes that are shorter than the ovary, very broad and flieshy at the base, thin membranous above and fringed 1 Stewart has noted, in the Country Gentleman variety of corn, that some spikelets bear two well-developed flowers inside each pair of glumes. He further points out that the irregularity in the arrangement of grains on the ear may be due to the development of the second flower in some of the spike- lets, which tends to throw some of the grains out of line. The same has been noted by Sturtevant and Kempton. l68 BOTANY OF CROP PLANTS on the edges. The lemma and palet of the fertile flower are short, broad and membranous. In pod corn, glumes, lemma, and palet attain a considerable size and enclose the grain. The single ovary bears one long style, the corn "silk," which is forked at the tip. It is well to remember that there is one silk for each grain on the cob. Weatherwax considers the corn silk a compound stigma rather than a style. The silk is indeed receptive to pollen a good portion of its length, possibly all. A hot, dry wind may wither the silks, thus destroying their receptivity to pollen. Fertilization of the ovules consequently does not take place, and the ovules do not mature. The short protuberance at the top of the ovary is considered by Weatherwax to be the style. It is traversed by a canal, the stylar canal. Three small rudimentary stamens have been observed by Baillon, and Weatherwax, in the fertile flower; the lodicules are absent. The small aborted flower has rudimentary stamens and pistil about equally developed; the lodicules are present. Hermaphroditic Flowers. — Ordinarily in corn the flowers are imperfect, that is either staminate or pistillate. Perfect or hermaphroditic flowers sometimes occur, however. Herma- phroditic flowers are far more common on the tassel than on the ear. East and Hayes record a sterile dwarf mutation which had nothing but hermaphroditic flowers. Hermaphro- ditic flowers have the stamens reduced. Lodicules are well developed in staminate flowers, reduced in hermaphroditic flowers, and altogether absent in fertile pistillate flowers. Montgomery observed hermaphroditic flowers on normal types of ears. The plants from these seeds came true to type. The seed was normal in every respect except that it had three fully developed stamens coming from near the base of the ovary. There were also three small stamens in the aborted flower of each pistillate spikelet. The plants ZEA 169 were of unusual appearance, being 5 feet high, with short internodes and broad leaves. Opening of the Flowers, and Pollination.^ — Cross-pollina- tion, consequently cross-fertilization, is the rule in corn but self-fertilization frequently occurs. Wind and gravity are the chief factors in pollen dissemination, although bees visit the flowers and are evidently concerned in pollen dispersal; they are relatively of far less importance than wind. In the case of the staminate inflorescence, the first flowers to open are those near the upper part of the central spike; blooming spreads both upward and downward, more rapidly downward. The same order of blooming occurs on the branches of the tassel. The time of pollen shedding depends upon weather con- ditions. Cold, wet, weather retards or even prevents the shedding of pollen. On the other hand, droughty conditions hasten the shedding of pollen, but delay the appearance of silks. Hence it may happen that under these conditions much of the pollen is scattered before the stigmas are pro- truded and receptive, and an incomplete filling of the ear results. On sunshiny days, most of the pollen is shed during th'e forenoon and, in some instances, late in the afternoon of the same day. Individual tassels usually remain in blossom from four to ten days or even more, depending upon the weather. Furthermore, the anther does not shed all its pollen as soon as it opens, but discharges it a httle at a time. In investigating a number (59) of varieties of corn as to the time elapsing between the appearance of anthers and appear- ance of first silks, Gernert finds marked variation. Both dichogamy (maturation of pollen and stigmas at different times) and homogamy (simultaneous maturity of pollen and stigmas) may occur. Furthermore, in dichogamous indi- lyo BOTANY OF CROP PLANTS viduals, protandry (anthers mature first) or protogyny (stigmas mature first) may occur. Out of 2,794 individuals in 59 varieties examined, he found 243 individuals homoga- mous, 92 protogynous, and 2,459 protandrous. It appears, then, that protandry is the rule in corn. In protandrous individuals, the first appearance of silks occurred from one to twenty-three days after pollen shedding, although the aver- age is two days. Varieties of corn dealt with in the above were pod, pop, flint, dent, soft, and sweet. Collins records the discovery of the protogynous habit in a variety of maize introduced from Granada, Spain. Ordinarily, however, dichogamy is seldom pronounced enough to completely ex- clude self-pollination. Gernert has also made observations as to the number of days intervening between the appearance of tassel and anthers. He finds, out of 3,319 individuals in 57 varieties, that, in the greatest number (514), the anthers appeared nine days after the tassel, and that in more than half of the individuals the first anthers appeared in seven to ten days after the tassels bearing them appeared. Pollen is produced in great quantities. It is estimated that each tassel produces 20,000,000 to 50,000,000 grains of pollen. Lazenby estimated that for each ovule in dent maize there are about 45,000 pollen grains produced. The size of pollen grains in corn varies. Pollen produced by central spikes is larger than that produced by laterals. Livingston observed that in Leaming corn the pollen grains from the central spikes were 0.02 millimeter larger on the average than those from lateral spikes. Of 12 varieties examined, Gernert finds that the average diameter of the pollen grain of corn varies from 0.08 to o.i millimeter. They are rather elHpsoidal in shape. Corn pollen soon shrivels after being shed, but its germinating power is not ZEA . 171 destroyed by this. However, pollen does not remain vialile much longer than twenty-four hours after shedding. Corn "silks" are long and plumose. The first silks to appear on the ear are those from grains slightly above the base. Generally, four or five days intervene between the appearance of lowest and uppermost silks. Hence, it will require four or five days to poUinate all the silks of an ear. Unfavorable climatic conditions, such as cold, wet weather or extremely hot days, may account for the incomplete ''filling out" of ears. The silks are receptive throughout their length. Best results are obtained when silk receives the pollen within a few days after its emergence from the husk. Silk exposed by splitting down the husks proved receptive. Again, fertihzation is not prevented when tips of silks are cut off. Fertilization, and Development of the Grain.^Just prior to fertilization, the ovary of corn is bent from the perpendic- ular so that the silk, instead of pointing directly out from the cob, points in a direction longitudinal to the cob. The ovary is on a stalk (rachilla) about 2.5 miUimeters long. The ovule almost fills the ovary cavity. It is attached to the wall of the ovary by more than one-third its circumference. The outer integument is incomplete while the inner covers the entire ovule, except the micropyle. This opening is just above the point of attachment of the lemma. The ovary' wall at this time, that is before fertihzation, possesses the following coats: 1. Single row of epidermal cells. 2. Many layers of parenchyma tissue, varying somewhat in size. 3. Single layer of inner epidermal cells. True records the presence of a pit "a short distance from 172 BOTANY OF CROP PLANTS the base of the style, on the posterior side." This is probably the "stylar canal" described by Poindexter. The outer and inner integuments vary in thickness from two to four layers. The very large embryo sac is located at the base of the nucellus. After fertilization, the following changes take place in the maturing grain: 1. Outer integument disappears. 2. Cells of inner integument become flattened, due to pressure from within. 3. The middle and inner cells of pericarp become compacted. 4. Cells of nucellus disappear to a large extent. 5. Hardening of the cell walls of the pericarp. 6. Fusion of pericarp and inner integument. Xenia in Corn. — Xenia is the term apphed to the phe- nomenon in which some character of the male appears at once in the seed. For example, in crossing a strain of corn having yellow endosperm with a strain having white endo- sperm, the grains produced are all yellow in every case, no matter which is used as the male parent. Xenia is shown only in case the parent having yellow endosperm is used as the male parent. The yellow endosperm character is dominant over white endosperm. Pollen from the plant bearing yellow endosperm will carry this character; pollen from the plant bearing white endosperm will carry the white character. When pollen, bearing the yellow endosperm character, is placed on the stigma of the grain having white endosperm, the pollen tube will discharge into the ovule two male nuclei, each bearing the character for yellow endosperm. One sperm nucleus fuses with the egg nucleus, the other sperm nucleus fuses with the two polar nuclei. The result of this triple fusion (second sperm nucleus and two polar nuclei) is the endosperm. Now, since yellow is dominant, ZEA 173 the grain that is formed by this double fertilization will have a yellow endosperm. Thus double fertilization explains the phenomena of xenia. It is of course true that, if in the above, pollen from the white endosperm-bearing plant were used, xenia would not be shown. Xenia, the visible effects of double fertilization, has been found in the following con- spicuous cases in corn — in each case below, the plant men- tioned first is the female: Non-starchy-seeded plants crossed with starchy-seeded plants always give starchiness. Non-yellow endosperm crossed with yellow shows yellow. Non-colored aleurone layer crossed with purple gives purple. Non-colored aleurone layer crossed with red gives red. Variation in the Com Plant.— There are marked individual differences in the plants of an ordinary field of corn. The plants may vary in height, vigor, leaf production, height of ears on the stalk, shape of ears, composition of kernel, etc. Moreover, there is scarcely any other crop plant in which we find more abnormalities or monstrosities than we do in corn. We have mentioned hermaphroditic flowers, both in the tassel and ear as one abnormality; to these we may add branched ears, tassels with a few or many kernels, variegated leaves, and variegated ears. In corn it is possible for the different kernels of an ear to receive pollen from many different plants, and from its own tassel. Hence, it usually happens that the grains on the same ear have different hereditary characters as shown by their varied progeny. This is well shown in variegated ears. If xenia occurs, the effects of this crossing may be evident the same season. For example, if pollen from dent corn fertilizes some of the ovules on an ear of sweet corn, those ovules appear starchy, while the other grains of the ear of corn, fertilized with sweet corn 174 BOTANY OF CROP PLANTS pollen are wrinkled. If xenia does not occur, the results of the mixing will not show up until the second year. Hence, ordinarily even though an ear of corn appears uniform, the separate kernels may have different heredity. The only way of testing its purity is to plant the grains and observe their progeny. Of course in this test, care must be taken to pre- vent strange pollen from blowing in. This is practically ac- complished by isolating the test plots. Results of Self-fertilization in Corn.^ — If our ordinary field strains of corn are self-fertilized for several generations the yield is considerably reduced. However, as a result of this inbreeding, we may be sure that all the kernels on an ear siarchuXj endosperrm / -^^ I endosperm Fig. 64. — Corn (Zea mays). A, median lengthwise section, cut parallel to broad surface, of grain of dent corn; B, cross-section of same through the embryo; C, section as in A of flint corn. have the same hereditary qualities. Furthermore, artificial self-fertiHzation for five or more successive years results in a strain that is not so complex in its characters, that is, a race which is comparatively uniform and pure. The Mature Grain of Corn.— The mature grain of corn varies considerably in shape (Fig. 64). In most varieties, ZEA 175 it is llattened in a plane at right angles to the length of the cob. The broader surface is roughly triangular in outline, being broader above than at the base. The groove indicates the position of the embryo. At the ''tip" of a mature grain, may still be found the papery remains ("chaff") of the palet, lemma, and glumes of the pistillate spikelets. The point of the grain, where it was attached to the cob, is the peduncle of the flower. The opposite indented end of the grain is often marked by a small point which is the remnant of the style. A longitudinal section of the corn grain parallel with the broad surface will show, with magnification, the follow- ing parts. 1. Pericarp, of several layers. 2. Testa, inner integument, of two layers. 3. Nucellar tissue. 4. Aleurone layer, outermost layer of endosperm, a single row of cells. 5. Starchy endosperm. 6. Horny endosperm. 7. Embryo. 8. Tip cap. • The pericarp and testa form the hull. It is possible to separate mechanically the starchy endosperm into two parts, the crown starch and tip starch. The following is a fair average of the relative proportions of the divisions of the grain, as given by Hopkins, Smith, and East: Per cent. Embryo 11. o Tip cap 1.5 "HuU" 6.0 Aleurone layer 8.0 to 14.0 Horny endosperm 45 • o Starchy endosperm 25.0 176 BOTANY OF CROP PLANTS Of course, there is a marked variation in the proportions of. these parts, and in their chemical composition. Chemical analysis of the above parts shows that the hull contains less protein (about 4 per cent.) than any other part of the grain. The endosperm is richest in protein, containing 20 to 25 per cent. The horny endosperm contains about 90 per cent, starch and 10 per cent, protein. The starchy endosperm is poor in total amount of protein (5 to 8 per Fig. 65. — Variation in the shape of corn grains. Which is the best propor- tioned kernel? Why? {After Mich. Agr. Exp. Sla. Bull. 34.) cent.). The germ is rich in oil, being composed of about 35 to 40 per cent, of oil and 19 to 20 per cent, protein. As much as 80 to 85 per cent, of the total oil content of the kernel occurs in the embryo. In high-protein corn kernels, the horny endosperm ex- tends up to and comes into contact with the embryo, the tip starch being entirely separated by it from the crown starch. In low-protein corn kernels, the amount of horny endosperm is reduced, tip and crown starch being continuous between it and the embryo. The embryo is much larger in high-oil kernels than in low-oil kernels. ZEA 177 Embryo. — In the normal Howlt, the embryo of corn is on the side of the grain toward the tip of the ear. Inverted grains have been found, however. This inversion is due to the development of the lower flower of the pair in the pistil- late spikelet. The embryo has the same structure as that of wheat. On account of its large size, the parts are readily made out. Its structure is best studied in a longitudinal section cut at right angles to the broad surface. The pri- mary root is conspicuous; the two laterals may be recognized as two swollen areas near its base. The scutellum, or single cotyledon, is traversed by a vascular system. The hypo- cotyl is just beneath the plumule, being terminated at its base by the primary root. Color. — Purple, blue, black, and red grains owe their color largely to a pigment located in the sap of aleurone cells. In some grains, there is a red sap in the pericarp. There is an absence of pericarp, aleurone and endosperm colors in white corn. In yellow maize, the coloring matter occurs both in the aleurone layer and in the endosperm. Com Starch Distinguished from the Other Common Starches. — The following key, adapted from Winton's Microscopy of Vegetable Foods, gives the characteristic microscopic differences between the common commercial starches. All or most of the grains rounded, not from aggregates. drains rounded, with central hilum; small grains globular or angular, Wheat. Grains large, of various shapes, with c.xcentric hilum. Potato. Grains polygonal or rounded, with one or more facets, mostly from aggregates. Grains very small, sharply angular, Rice. Grains large, polygonal or rounded; hilum with clefts. Maize. Germination of Com. — The germination of corn may be judged from the following data: Sachs says: optimum 9i°F., 178 BOTANY OF CROP PLANTS maximum ii4.8°F., and minimum 4i°F. Sturtevant further shows that corn germinates in from ten to twenty days at a temperature of 43.7°F., while at from 48.6°F., to 58.5°F., it germinates in from five to ten days. In germination, the primary root appears first, at the tip of grain ; soon the plu- mule breaks through the pericarp at about the middle of the grain. The young germinating grain consists of a primary root projecting at the peduncle end, and the plumule emerg- ing through a slit in the pericarp at about the middle of the grain, and pointing in the opposite direction. On the sides of the primary root, two secondary ones soon appear, making a total of three roots in the primary root system. In the seedling, there is, as in other cereals, a more or less elongated axis between the base of the coleoptile and the grain. This has been named the mesocotyl by some mor- phologists. Collins described seedlings of maize grown by the Indian tribes of the southwestern United States, that may develop, under conditions of deep planting, a mesocotyl up to 36 centimeters in length. Classification. — The many different varieties of cultivated corn are all included under the one name, Zea mays L. Sturtevant has divided this species up into "species groups" (subspecies), the most important of which are the following:* 1. Zea tunicata, pod corn. 2. Zea everta, pop corn. 3. Zea indurata, flint corn. 4. Zea indentata, dent corn. 5. Zea amylacea, soft corn. 6. Zea saccharala, sweet corn. 7. Zea amylea-saccharata, starchy sweet corn. *The specific name "mays" is omitted, for convenience, from the following. ZEA 170 Gernert describes a type of corn with branching ears and highly Ijranching tassels, which he considers as a distinct subspecies and for which he suggests the name Zca mays ramosa. Collins describes a new type of Indian corn from China. This has erect leaf blades, some upper leaves ar- ranged in a monostichous manner, silks developing inside the leaf sheath, and grains with a peculiar waxy endosperm. Zea Fig. 66. — The six principal types of corn. From left to right, pod corn. pop corn, flint corn, dent corn, soft corn, and sweet corn. {After Montgom- ery.) canina Watson, the Maiz de Coyote, is a branching plant producing many small ears (2 to 4 inches long) on lateral branches. It has been produced artificially by crossing a common maize and teosint^. It is said to grow wild in Mexico at the present time. Zea mays japonica is an orna- mental sort with small, flinty grains. Zea mays hirla is a hairy, South American corn. Zea mays curagua is a form with serrate leaves. l8o ■ BOTANY OF CROP PLANTS The distinguishing characteristics of the seven groups above are shown in the following key: Key to "Species Groups" of Corn Each kernel enclosed in husks (glumes, lemma, palet); the ear is also enclosed in husks; a rare form, considered by some to be the primitive t3^e, Zea tunicata (pod corn). Each kernel naked, not enclosed in pod or husk: Grains with popping properties; popping is due to the turning inside out of the kernel through the explosion of the contained moisture when heat is applied; pericarp is thick and tough; excessive proportion of horny (corneous) endosperm; kernels and ears small, Zea everta (pop corn). Grains without popping properties. No corneous endosperm, hence grains are soft; shaped like flint corn; no indentation; the mummy corns of Peru, Mexico, and southern United States probably belong to this group, Zea amylacea (soft corn) . Corneous endosperm present. Grains more or less wrinkled or shrivelled; kernels horny and trans- lucent in appearance. Grains horny throughout, Zea saccharala (sweet corn). Grains with upper half horny and translucent, the lower half starchy, Zea amylea-saccharata (starchy sweet corn). Grains not wrinkled, smooth. Starchy endosperm extending to top of kernel; corneous endosperm at sides; shrinkage of starchy endosperm at top of grain causes a drawing in of pericarp and hence the characterist c dent formed (Fig. 64), Zea indeniata (dent corn). Starchy endosperm enclosed by the corneous endosperm; hence there is no shrinkage of top of grain and no dent formed (Fig. 64), Zea indurata (flint corn). Zea amylea-saccharata (starchy sweet corn) is a group of only botanical interest. Some seed of this was found in the San Padro Indian collection Ijy Dr. Palmer and sent to Sturtevant in 1886. This seed was planted at Geneva, New York, but the crop failed and the seed was lost. In Zea saccharata, the power to develop starch grains to maturity has been lost. The starch that is formed remains ZEA l8l small, angular, and docs not have the appearance of the typical corn starch granule. Sweet corns may be regarded Fig. 67. — Teosinte (Euchlaena mexicana). (After Collins and Kemplon in Journal of Heredity.) as dent, flint, and pop corns that have lost the power to mature starch normally. Origin of Maize.^Although maize or Indian corn has been l82 BOTANY OF CROP PLANTS in cultivation since prehistoric times, it is unknown in the wild state. It is generally agreed, however, that it is dis- tinctly of American origin. The nearest known wild relative of maize is a Mexican grass, teosinte {Euchlana mexicana), with which it is known to hybridize (Fig. 67). Harshberger is inclined to believe "that Indian corn is the result of a cross between teosinte and a race or variety of the plant produced by successive cultivation of the wild plant until its characters as a variety or a race have become fixed." Collins produces evidence to show that maize originated as a hybrid between teosinte and as unknown grass belonging to the tribe Andropogoneae. He believes this grass to be much like the earless varieties of pod corn {Zea kmicata). Mont- gomery suggests that teosinte and corn had a common ances- tor, which was a "large, much-branched grass, each branch being terminated by a tassel-like structure, bearing herma- phrodite flowers." His views coincide with those of East and Hayes (see page 164). Environmental Relations. — Corn is a native of semi-trop- ical America. Its range of distribution has been extended widely through culture. A number of varieties will mature grain as far north as southern Canada, and as a green fodder it is raised in still colder regions, where the season is too short to mature the grain. Flint varieties are now grown quite abundantly through- out northern Wisconsin; they are better adapted to cool climates than dent corn. In general, corn is not a big crop north of the summer isotherm of 69°F. The principal corn belt of the United States is a strip running from eastern Nebraska to western Ohio, the northern limit being southern Wisconsin and Minnesota. This is a region with warm sum- mer days and nights. The chief limiting factor to corn grow- ing in the northern tier of States is cool nights. ZEA 183 Reference to page 117 shows that the water requirement of corn stands between that of sorghum and wheat. There is a significant difference in the water requirement of the varieties of corn, indicating that some may be more drought- resistant than others. Corn is being raised with profit on the dry lands of the West. There is a close correlation between the yield of corn and the rainfall for June and July. The critical month is July. Smith says that the most critical ten-day period for corn, in Ohio, is from August i to 10, the period following blossoming, when the weather must be wet and moderately cool. In the corn districts west of the QSth meridian, hot winds sometimes prove fatal to corn. These winds are particularly harmful during the critical periods of "tasseling" and "silking." Corn thrives best in a well-drained, medium loam soil, such as is found in the river bottoms of the Mississippi Valley. It will grow on soils so rich in nitrogen as to cause the lodging of the small grains. Uses of Com.^ — No other cereal is put to such a variety of uses as is corn. Some economical use has been found for nearly every part of the plant. There are numerous manu- factured corn products and by-products. Corn meal, both yellow and white, is one of the chief forms in which the grain is used as a food for man. Whole meal includes the embryo, endosperm and hull, while new process meal has the embryo and hull removed. Other forms in which corn as a human food is used are: hominy, green corn, canned corn, corn oil, corn flakes, pop corn, starch, and glucose. The sweet corn canning industry is a large one. Corn starch from which the protein and mineral matter have been removed by treat- ment with dilute alkaline solutions gives a flour which is used largely in the preparation of puddings, blanc manges, etc. 184 BOTANY OF CROP PLANTS Com oil is obtained from the embryo. When freshly prepared, it is pale yellow in color. It is employed in the manufacture of soap, and paints, and when mixed with lin- seed oil, it has some value as a grinding oil. Corn oil is also sometimes vulcanized into a cheap grade of rubber. Corn Starch. — About 50,000,000 bushels of corn are used annually in the United States in the manufacture of com- mercial starches, and products derived from them. In the manufacture of corn starch, the corn is steeped from two to four days in warm water containing about 0.2 per cent, of sulphurous acid. Steeping is instituted in large wooden vats holding about 2,000 bushels of corn. When the grains are softened sufficiently, they are lead through a Fuss mill which thoroughly breaks up the grain. The embryos are separated from the rest of the grain material, and removed to another receptacle. The disintegrated grains are freed from the embryos, mixed with water, more finely ground and then shaken through bolting-cloth sieves. Starch and gluten pass through the sieves, while the courser materials, such as frag- ments of the pericarp, are caught by the sieve. The liquor containing starch and gluten is passed over tables, very slightly inclined, and as the liquid slowly flows down these tables, the starch granules settle, while the lighter particles of gluten are carried off the lower end. The starch is re- moved from the tables, washed, and kiln-dried. Glucose. — The commercial "glucose" is a thick syrup — a product of the partial hydrolysis of starch. The manufac- ture of corn starch has been described. The "green starch'' from the tables is made into a thick cream by mix- ing with water. This is then passed to converters where the starch is treated with hydrochloric acid to bring about its partial hydrolysis. The converted liquor is blown out of the converters into the neutralizer, where it is treated ZEA 185 with a dilute solution of sodium carbonate, which neutralizes the acid, and precipitates the dissolved iron, and coagulates the colloidal albuminoids. The neutral liquor is then filtered, first in bag filters, and then in bone-char filters. From the first bone-char filters, there issues a light liquor. This is evaporated to increase its concentration, and passed on as heavy liquor to the bone-char filter again. The liquor that results from this second filtering is boiled down in vacuum pans, whence it comes as the finished glucose. Pure glucose syrup has little flavor, and but half the sweet- ness of cane syrup. Maize syrup is mixed with varying quantities of cane syrup and sold as a substitute for golden syrup and molasses. It is the basis of many manufactured jellies and preserved fruits. Grape Sugar. — This is a crude sugar made from starch, in a manner very similar to that employed in the manufac- ture of glucose. However, hydrolysis is more complete, the process of conversion being carried to the point that no dex- trin is precipitated when a sample is placed in strong alcohol. Grape sugar appears on the market as a hard, waxy solid. It finds considerable use in the manufacture of sparkling ales; and, also, as a reducing agent in indigo dyeing, and other industries. Artificial Gums. — These are known as dextrins and British gums, and are made from starch. Starch is heated to a temperature varying from 170 to 2 7o°C. During this proc- ess, the starch may be treated with dilute nitric acid to bring about hydrolysis, although if high temperatures are used, the addition of acid is unnecessary, as the starch itself con- tains enough acid and water to effect hydrolysis. Dextrins and British gums are used on envelopes and postage stamps, and also in many of the textile industries. Stock Food. — Corn fodder includes the whole plant — stalks. 1 86 BOTANY OF CROP PLANTS leaves, and ears- — and in this form is fed to stock. Corn stover is the stalks of corn from which the ears have been husked; the stalks may be fed in the bundle form or shredded. Fodder is an important silage crop. In the form of silage, it makes a highly nutritious, succulent feed throughout the winter. Silage is a forage prepared by fermenting green, fresh, plants in a specially constructed air-tight receptacle, called a silo. The material to be ensilaged is cut into fine pieces and packed into the silo. Forage crops include, ac- cording to common usage, those plants which are grown for their vegetative parts and which are eaten, either in the green or dry state, by herbivorous animals. Some plants, such as sorghums, are grown for their grain and also for their herbage, that is, they are both a cereal and a forage crop. Corn is also both a cereal and a forage crop. The grass family (Gramineae) and the pea family (Leguminosae) furnish the great majority of forage plants. Corn grain and corn bran are important stock foods. Other Corn Products. — The pith from the stalks is made into explosives and also employed as a packing material where extreme hghtness of weight is required. Corn cobs are still in demand for pipes. A fine grade of charcoal is manufactured from corn cobs. Paper is made from the stalks, and packing for mattresses from the husks. When oil is pressed from the embryos, there is left the corn cake, which may be utilized as a food for stock. Gluten meal, a by- product from starch factories, is also not infrequently fed to stock. Corn is the most economical source of starch for alcohol manufacture in the United States. One ton of corn gives about 90 gallons of 94 per cent, alcohol. Production of Corn.^ — In 1914, the United States produced 2,672,804,000 bushels of corn, which was over 70 per cent, of total production for the world. The country ranking ZEA 187 second in its corn output was Argentine with 338,235,000 bushels. The ten leading States in the order of their pro- duction of corn in 191 5 were IlHnois, Iowa, Nebraska, Mis- souri, Indiana, Texas, Kansas, Ohio, Oklahoma, and Ken- tucky. The total acreage in corn in the United States that year was 108,321,000 and the total farm value of the 191 5 corn crop, on the basis of the price of corn December i, was $1,755,859,000. Fig. 68. — Percentage of the world's supply of corn produced in the various countries in 1914. References JiuHUTiNSKY, GusT.'W. Entvvicklungsabwclchungen bcim Mais. Her. Dcul. Bot. Gesell., 32: 179-188, 1914. Bo\VM.\N, M. L., and Crossley, B. W.: Corn: Growing, Judging, Breeding, Feeding, Marketing. Waterloo, Iowa, 191 1. BuRTT, Davy J.: Botanical Characters of the Maize Plant. Transvaal Agr. Jour., 7: 348-395, 1909- Incomplete Dichogamy in Zea Mays. Jour. Bot. (London), 47:180-182, 1909. Maize, Its History, Cultivation, Handling, and Uses. Longmans, (Jreen & Co., 1914. Collins, G. N.: A New Type of Indian Corn from China. U. S. Dept. .\gr. Bur. Plant Ind. Bui. 161: 1-25, 1909. (0 1- z £0 _| Q o o bJ i Z O Q 02 Q. ^ Z a: o 1 - / ft- t^ < r^^ ^i <5^i 3 S « SSs; ass 990,000 656,000 1,053,000 i 1,155.000 i 516.000 770.000 600.000 ueoooo 625.000 442,000 35.000 11 Si S' 1 ^'1 -,-2^ SI iiiSiigigis 53 1 ii f^^i^^filMl 1 i^ii^iiiii- SS => 7^ J |I1S! ■■( §s mil ^ \ / .• \!t*4^m:^''i?^ • •(■••.••••••' Mi ^ d^JI n-M pf^l^lg: ^^ J ••.■•■.:V;--Jv ^^Kii ?; ■.■'."••J mpy ' V^:'-'" ^B r . — -J ' ■ 1 . Iv ■ , / J / r Is to a Z z §2 < < i£2i?r^^c^-S2D!'^ |i S"ffi"SSi£5S°"^-, 5 SsSSSSssSsi |i 67,897.051 67.682.489 55,558,737 52,906,842 49,163,034 41,494Zi7 39.374,569 38.295,141 37,609,544 34.063,531 -c iBiii^Jii is 376.164.000 303.000.000 190.950.000 209.450.000 213.000.000 156,040.000 172.050.000 123.900.000 114,000,000 175,075,000 ii 390,218,676 341,750,460 195,496,433 191,427,087 180,132,807 157,513,300 154,651.703 94,283,407 83,348,024 75,498.695 ^ -^ 5 Jjsji iJi _££j ZEA 189 Apogamy in the Maize Plant. U. S. Nat. Mus. Contrih. Nat. Herbarium, 12: 453 455, iQog- The Origin of Maize. Jour. Washington Acad. Sci., 2: 520-530,1 912. A Variety of Maize with Silks Maturing Before the Tassels. U. S. Dept. Agr. Bur. Plant Ind. Cir. 107: i-ii, 1913. A Drought-resisting Adaptation in Seedlings of Hopi Maize. U. S. Dept. Agr. Jour. Agr. Research, 1:293-302, 1914. CoRRENS, C: Untersuchungen iiber die Xenien bei Zea mays. Ber. Deut. Bot. Gesell., 17:410-417, 1899. Crozier, a. a.: Silk-seeking Pollen. Bot. Gaz., 13:242, 1888. East, E. M.: Inheritance of Color in the Aleurone Cells of Maize. Amer. Nat, 46:363-365, 1912. A Chronicle of the Tribe of Corn. Pop. Sci. Mo., 82:225-236, 1913. East, E. M., and Hayes, H. K.: Inheritance in Maize. Conn. Agr. Exp. Sta. Bull. 167:1-142, 1911. Fisher, M. L.: Report of Work in Corn Pollination, I. Proc. Ind. Acad. Sci., 1908. Report of Work in Corn Pollination, II. Proc. Ind. Acad. Sci., 1910. Report of Work in Corn Pollination, III. Proc. Ind. Acad. Sci., 191 1. Gager, C. S.: An Occurrence of Glands in the Embryo of Zea Mays. Bull. Torrey Bot. Club, 34: 125-137, 1907. Gernert, W. B.: Methods in the Artificial Pollination of Corn. Am. Breeders' Assn., 7: 353-367, 1911. A New Subspecies of Zea Mays. Am. N.at., 47 : 6i6"-622, 191 2. GuiGNARD, L.: La double fecondation dans le mais. Jour. Bot. (Paris), 15: 37-50, 1901. Harshberger, J. W. : Maize: A Botanical and Economic Study. Contrib. Bot. Lab. Univ. Pa., i : 75-202, 1893. Fertile Crosses of Teosinite and Maize. Gard. and Forest, 9: 522-523, 1896. A Study of the Fertile Hybrids Produced by Crossing Teosinte and Maize. Contrib. Bot. Lab. Pa., 2, 1901. Hopkins, C. G., Smith, L. H., and East, E. M.: The Structure of the Corn Kernel and the Composition of its Different Parts. 111. Agr. Exp. Sta. Bull. 87: 77-112, 1Q03. Hus, H., and Murdock, A. W.: Inheritance of Fasciation in Zea Mays. Plant World, 14: 88-96, 1911. Kellerman, W. a., and Swingle, W. T.: Preliminary Study of the Recep- tivity of Corn Silk. 2d Ann. Rept. Kans. Agr. Exp. Sta., 353-355, 1890. Bibliography of Cross-fertilization of Varieties of Corn. 2d Ann. Rept. Kans. Agr. E.\p. Sta., 346-353, 1890. 190 BOTANY OF CROP PLANTS Experiments in Cross-fertilization of Corn. 2d Ann. Rept. Kans. Agr. Exp. Sta., 288-334, 1890. Experiments in Crossing Varieties of Corn. 2d Ann. Rept. Kans. Agr. Exp. Sta., 2: 288-334, 1890. Kempton, James H.: Floral Abnormalities in Maize. U. S. Dept. Agr. Bur. Plant Ind. Bull. 278: 1-16, 1913. Montgomery, E. G.: What is an Ear of Corn? Pop. Sci. Mo., 68: 55-62, 1906. Perfect Flowers in Maize. Pop. Sci. Mo., 79: 346-349, ion. The Corn Crops. * The Macmillan Co., New York, 1913. Peirson, Henry: Abnormal Development in Maize. Jour. Bot. (London), 49: 347-348, 1911- PoiNDEXTER, C. C: The Development of the Spikelet and Grain of Corn. Ohio Nat., 6, 1903. Sargent, Ethel, and Robertson, Agnes: The Anatomy of the Scutellum in Zea Mays. Ann. Bot., 19: 115-123, 1905. Shoesmith, V. M.: The Study of Corn. Kans. .'Vgr. Exp. Sta. Bull. 139: 223-249, 1906. The Study of Corn. Orange Judd Co., 1910. Stewart, Alban: The Pistillate Spikelet in Zea Mays. Science, n.s. 42: 694, 1915. Sturtevant, E. L.: Notes on Maize. Torrey Bot. Bull. 21: 319-343, 1894. Varieties of Corn. U. S. Dept. .^gr. Office E.xpt. Stats. Bull. 5;: 1-103, 1899. Weatherwax, Paul: Morphology of the Flowers of Zea Mays. Bull. Torrey Bot. Club, 43: 127-144, 1916. Webber, H. J.: Xenia, or the Immediate Effect of Pollen in Maize. U. S. Dept. Agr. Div. Veg. Path, and Veg. Phys., 22: 1-44, 1900. CHAPTER XV ANDROPOGON SORGHUM ( Sorghums i) Habit of Plant, and Roots. — All sorghums are annual. The root system is well developed. The roots are generally finer and more fibrous than those of maize. The root crowns and laterals show a vigorous growth. Sorghum is more of a surface feeder than corn, its roots being chiefly in the first 1 8 inches. The roots of all sorghums are tough and wiry. Stems and Leaves. — The culms vary in height from 3 to 15 feet. They are solid; the internodes and leaf sheaths are about equal in length. Sorghums produce both "suckers" and side branches from buds placed in the axils of the leaves. As many as 10 or 15 suckers may be produced from one plant; they differ from the main stalk in that they are less tall, and mature later. Side branches do not appear until the main stem is headed out. The heads on these branches are smaller and less productive than those on the main stalk, and they mature much later. The leaves are very similar to those of corn. Inflorescence. — This is a panicle, which, with a few excep- tions {e.g., broom corn), is rather compact. It is called the "head." These heads may vary (Fig. 73) a great deal in shape and color. The axis of the inflorescence is rather angular. The side branches are in apparent whorls, one above the other. The spikelets usually occur in pairs (Fig. 70), although toward the tip of the inflorescence they may occur in threes. ' The term "sorghum" includes all the groups known in the United States as mile, kowliang, shallu, durra, broom corn, and kafir. 191 192 BOTANY OF CROP PLANTS Spikelets and Flowers.^ — It was stated that the spikelets usually occur in pairs. One is sessile, the other pedicelled. The sessile one is broad, thick, and fertile; the pedicelled narrow, long, and staminate. Whenever three spikelets are in a group, one is sessile and perfect, and two are pedicelled and staminate; sometimes one of the two stalked spikelets may be perfect. horny endosperm awn---!f^qrch\i \^ endosperm- Znd glut \ Fig. 70. — Sorghum (Andropogon sorghum). A, pair of spikelets; B, grain in section; C, grain, external. X 5- Fertile Spikelet (Fig. 71).— The sessile spikelet has thick, leathery glumes of about equal length. The outer one par- tially wraps about the inner. The latter is narrower and more gradually tapering at the tip. Within the two glumes of this sessile spikelet, are two flowers; the lower sterile, the upper with both stamens and pistil. The so-called "third glume" of some descriptions is the lemma of the lower, sterile flower. Moreover, it is the only remnant of this flower. It ANDROPOGON SORGHUM 193 encloses the parts of the fertile flower. The lemma of the fertile flower is broad, hairy, and two-cleft at the tip; there arises in the cleft, as a rule, a long awn which projects from the spikelet. The awn may be very short or only represented by a bristle. The palet is frequently absent; when pres- lemma of sterile Jlower- anfher- Fig. 71. — ovarv lemma of fertile Jlower- -Spikelet of sorghum (Andropogon sorghum) dissected. Lodicule X 10, all others X 5- ent, it is small and thin. There are two lodicules, which are much broader than long, truncate, fleshy, and usually thickly hairy. Three stamens are present. The sessile, ovate ovary does not bear a tuft of hairs at the tip, such as is found in wheat, oats, rye, and barley. The two styles are thread-like and bare for the lower two-thirds of their length, and then spread out into bushy stigmas. 194 BOTANY OF CROP PLANTS Staminate Spikelet. — The stalked spikelet is narrower, and more pointed than the fertile one. It is two-flowered. It is subtended by two leathery glumes. Immediately within this pair is the lemma of the sterile flower of the spikelet. Then comes the lemma of the staminate flower; it may be short-awned or awnless; the palet of this flower is absent. The lodicules and stamens resemble those of the fertile spike- let. There is no pistil. • Opening of Flowers and Pollination. — Flowers do not be- gin to open on the inflorescence until the latter is entirely out of the leaf sheath. The first flowers to open are those near the tip of the head. Blooming proceeds from the tip down- ward. As a rule, flowers at the tip of an inflorescence have shed their pollen, and closed, when the lower flowers of the head are just beginning to bloom. Flowers on branches be- longing to one whorl are usually in about the same stage of blooming. In nearly all cases, the sessile spikelet of a pair is the first to open. The stalked spikelets may sometimes fail to protrude their stamens. Most of the flowers open in the early morning; there is but very slight amount of blooming during the day. The stigmas may protrude to a slight extent first. (Fig 72) . They are followed by the anthers. When the flower starts to open, the whole process takes place within from ten to fifteen minutes. The spreading of the glumes, and the emergence of anthers and styles may be so rapid in some in- stances as to be seen with the hand lens. The stamens ex- tend their full length, as a rule, and the anthers swing on long filaments. In some cases, however, the anthers never fully project from between the glumes, but shed their pollen, and dry up, half or one-fourth caught by the glumes. When the anthers are partly out, the stigmas are fully protruded. No sooner are the anthers visible than they begin to dehisce by two narrow slits at the tip only. The stigmas and pollen- ANDROPOGON SORGHUM 195 shedding anthers may be in contact at time of opening, and since the stigma is recei)tive at this time, some seh'-polHnation must take place. Pollination between flowers of the same Fig. 72. — Four stages in the opening of the spikelet of sorghum (Andropogon sorghum). X 5. plant is very common. The upper flowers are shedding pol- len in abundance, as the receptive stigmas of lower flowers are opening. And, in the light breeze of the morning, the head is 196 BOTANY OF CROP PLANTS moved enough to shake pollen out. Cross-pollination is also very common. Individual flowers do not, as a rule, remain open longer than the evening of the day they open. The brown and withered stamens and stigmas commonly protrude from between the closed glumes. The different types of sorghum cross readily. Fruit. — The mature grain may be entirely or in part en- closed by the "glumes." It is oval, a little longer than broad, smooth, and tipped with the remains of two style branches. The position of the embryo is seen at the base of the grain on one of the flat surfaces. The point of attachment — an oval, brown area — is found at the base of the grain on the other flat surface. The seed is flattened in the durras, pyriform in some of the sorgos, and globular in kafir, kowliang, and shallu. In some types of sorghum, the pericarp bears starch. The aleurone layer consists of one row of small cells. The starchy endosperm is mealy within and more or less horny without. Varieties. — The sorghums are divided into two main di- visions: (i) saccharine or sweet sorghums, and (2) non-sac- charine sorghums. Saccharine sorghums are tall, leafy, and have an abundance of sweet juice, and a light crop of seed. The chief varieties are Amber, Orange, and Sumac. Non- saccharine sorghums are more stocky, as a rule, contain less juice, and have a heavy crop of seed. Non-saccharine sorghums are divided into three groups; (i) kafir group, in- cluding those with erect, long cylindrical heads full of obovate seeds (kafirs, white milo, etc.) ; (2) durra group, including those with thick, compact, ovate, pendant inflo- rescences, and large, flattened seeds (yellow milo, durra, feterita) ; and (3) broom corn group, in which the heads are loose and spreading. Frequently the heads are on recurved stems, called "goose necks." ANDROPOGON SORGHUM igy Key to the Principal Groups of Sorghum^ Pith juicy. Juice abundant and v-ery sweet. Internodes elongated; sheaths scarcely overlapping; leaves 12 to 15 (ex- cept in Amber varieties); spikelets elliptic-oval to obovate, 2.5 to 3.5 millimeters wide; seeds reddish brown, Sorgo. Juice scanty, slightly sweet to subacid. Internodes short; sheaths strongly overlapping; leaves 12 to 15; peduncles erect; panicles cylindrical; spikelets obovate, 3 to 4 millimeters wide: lemmas awnless, Kafir. Internodes medium; sheaths scarcely overlapping; leaves 8 to 11; ped- uncles mostly inclined, often recurved; panicles ovate; spikelets broad- ly obovate, 4.5 to 6 millimeters wide; lemmas awned, Milo Pith dry. Panicle lax, 2.5 to 7 decimeters long; peduncles erect; spikelets elliptic- oval or obovate, 2.5 to 3.5 millimeters wide; lemmas awncd. Panicle 4 to 7 decimeters long; rachis less than one-fifth as long as the panicle. Panicle umbelliform, the branches greatly elongated, the tips droop- ing; seeds reddish, included, Broom Corn. Panicle 2.5 to 4 decimeters long; rachis more than two-thirds as long as the panicle. Panicle conical, the branches strongly drooping; glumes at maturity spreading and involute; seeds white or somewhat buff, Shalln. Panicle oval or obovate, the branches spreading; glumes at maturity appressed, not involute; seeds white, brown, or reddish, Kowliang. Panicle compact, i to 2.5 decimeters long; peduncles erect or recurved; rachis more than two-thirds as long as the panicle. Spikelets elliptic-oval or obovate, 2.5 to 3.5 millimeters wide; lemmas awned, KoivUang. Spikelets broadly obovate, 4.5 to 6 millimeters wide. Glumes gray or greenish, not wrinkled; densely pubescent; lemmas awned or awnless; seeds strongly flattened, Diirra. Glumes deep brown or black, transversely wrinkled; thinly pubescent; lemmas awned; seeds slightly flattened, Milo. Origin of Sorghums.— The wild form from which our culti- vated sorghums have been derived is Andropogon Iialepensis (Johnson grass). This species is native to tropical and sub- tropical parts of the Old World. The view is now quite ^ Taken from Ball. 198 BOTANY OF CROP PLANTS ANDROPOGON SORGHUM I99 generally adopted that the present-day cultivated sorghums can be divided into two groups, each of which had an independent origin in Asia and Africa respectively. Environmental Relations. — Sorghums are of tropical origin, and are more at home in regions with warm, sunshiny summers. The plant will undergo high temperatures. It is sensitive to low temperatures, and consequently cannot be planted as early in the season as the other small cereals. The sorghums are either able to resist or to escape drought. For this reason they have become one of the principal crops on the non-irrigated lands of the West. Their resistance to drought is due largely to their low water requirement, along with their ability to roll the leaves with approaching dry periods, and thus reduce the water-losing surface, and also to their ability to remain alive during a period of drought and quickly resume growth when moisture is available. In this last respect the sorghums differ from corn, for corn is unable to remain in a dormant state for^ very long time. The sor- ghums are not as easily affected by hot winds as corn. This is an important characteristic adapting them to the semi-arid regions. Sorghums will grow on a variety of soils. They are some- what more resistant to alkali salts than the other grain crops. Uses of Sorghums. — The saccharine or sweet sorghums are grown for syrup and for forage. The juice is extracted from the canes. The leading State in sorghum-syrup pro- duction is Tennessee. The non-saccharine sorghums are grown chiefly for their grain, but also for forage. The Chi- nese and Manchus put the grain sorghums to a great variety of uses. For example, a fermented drink is made from the seed, the heads are used for fuel and brooms, the leaves for fodder and for mats, the stalks for the construction of baskets, fences, building material, laths, playthings, posts, thatchings. 200 BOTANY OF CROP PLANTS wind breaks, and window shades, and even the roots and stubble are used as fuel. The broom-corn groups of sor- ghums are grown for their grain, and certain varieties with long rachi are made into brooms. For this purpose the heads are used. Brooms are made from two different groups of broom corn: tall-growing or Standard, and divarf. Fully two-thirds of the total broom-corn crop of the United States is dwarf broom corn. It produces a fiber that is finer than that of the tall-growing sort; and, too the head is not so firmly attached to the upper node. This latter character permits the "brush" (inflorescence) to be harvested by pulling. After threshing the grain from the heads, they are cured in sheds or out of doors in ricks. They are then graded and baled, and either stored or shipped directly to the broom factory. The "straws" of a broom are the rachises of the sorghum inflorescence. Oklahoma, Kansas, and Texas, in the order named, are the leading broom-corn States. References Ball, CARLExbN R.: Saccharine Sorghums for Forage. U. S. Dept. Agr. Farmers' Bull. 246: 7-18, 1906. Three Much Misrepresented Sorghums. U. S. Dept. Agr. Bur. Plant Ind. Cir. 50: 1-14, 1910. The History and Distribution of Sorghum. U. S. Dept. Agr. Bur. Plant Ind. Bull. 175: 1-63, 1910. Better Grain-sorghum Crops. U. S. Dept. Agr. Farmers' Bull. 448: 1-36, 1911. The Importance and Improvement of the Grain Sorghums. U. S. Dept. Agr. Bur. Plant Ind. Bull. 203: 1-45, 191 1. The Grain Sorghums, Immigrant Crops that Have Made Good. U. S. Dept. Agr. Yearbook, 1913: 221-238. Hackel, E.: Die kultivirten Sorghum — Formen und ihre Abstammung. Jahrb. (Engler), 7: 1 15-126, 1885. Piper, C. V.: The Prototype of the Cultivated Sorghums. Jour. Am. Soc. Agron., 7: 109-117, 1915. ANDROPOGON SORGHUM 20I Hartley, Charlks P.: Broom Corn. U. S. Dept. Agr. Farmers' Bull. 174: 1-30, 1903. RoTHGEB, B. E.: Dwarf Broom Corns. U. S. Dept. Agr. Farmers' Bull. 768: 1-16, 1916. Warburton, C. W.: The Non-saccharine Sorghums. U. S. Dept. .\gr. Farmers' Bull. 288: 1-28, 1907. CHAPTER XVI ORYZA SATIVA (Rice) Habit, Roots, Stems, Leaves. — Common cultivated rice is an annual plant, which grows best under swampy or very moist conditions. There are upland varieties pro- duced with irrigation, but the lowland type is the sort almost entirely grown in the United States. The seedling has one seed root. The root system is fibrous; the first, second, and third nodes give rise to adventitious roots. The first whorl of permanent roots is close to ^■^ inch above the lower end of the culm. It is more shallow in very moist ground than in dry soil. The plant tillers freely, sending up usually four or five hollow stems to a height of 2 to 6 feet. The leaf sheaths are open, and the blades are from 8 to 12 inches long and ^^ to i inch wide. The ligule is long, acute or obtuse, and easily splits into two parts. It is much shorter and more rounded on the upper leaves than on the lower. The auricle is white or green, cartilaginous or membranous, and hairy. Inflorescence and Spikelet. — The inflorescence is a pan- icle (Fig. 74). Its branches are either single or in pairs. The spikelet (Fig. 75) is compressed laterally. It is one- flowered. There are two small scale-like or bristle-like glumes, underneath each of which is a very minute, rudi- mentary glume. The lemma is compressed, parchment-like and five-nerved. The palet is similar to the lemma in size and texture, but is only three-nerved. Both may be awned or awnless. The broadly oval lodicules are small, thick, and ORYZA SATIVA 203 fleshy. Rice differs markedly from the other common cereals in having six well-developed and functioning stamens. The ovary is somewhat longer than broad, smooth, and bears two Fig. 74. — Panicle of rice (Oryza sativa). Styles, and sometimes a short, rudimentary third one. These three are sometimes grown together at the base. Pollination and Fertilization. — Rice is normally self-polli- 204 BOTANY OF CROP PLANTS ^Plh- lemma ^^lumej nated. The flowers at the tip of the inflorescence are the first to open. Flower opening continues throughout the day. The stamens are the first flower parts to appear. After they are extended full length, the lemma and palet open wider; and the stigmas protrude. Usually the stigmas draw back between the palet and lemma after pollination, although they may remain outside. Although self-fertilization is the normal process, cross-fertilization is not altogether pre- cluded. Grain. — The rice grain (caryopsis) is surrounded by the lemma and palet, or palet alone. These two structures form the "hull." Rice enclosed in the hull is known as "paddy." Rice from which the hull has been removed is "cleaned rice." The rice grain (Fig. 76) is smooth, longer than broad, and elliptical in cross-section. There are two longitudinal parallel ridges on each of the flat surfaces. The grain of common rice is shiny and transparent. This appearance is due to the glassy endosperm. Occasionally there are grains that appear dull; in such, the endosperm is starchy on the outside and horny within. Grains with dull areas here and there are not uncommon. An interesting rice is Oryza glutinosa, the grains of which always appear dull. A cut surface of this rice is de- scribed as paraflin-like in appearance. The starch grains behave quite differently from those of common rice. They color yellow-brown with iodine instead of violet- Fig. 75. — Spikelet of rice (Oryza sativa). Fig. 76.— Kernel of rice (Oryza sativa). e, embryo. X 5- ORYZA SATIVA 205 When it is cooked, there is tormed a mass the particles of which stick closely together; the single grains do not remain separate. There are rices with grains pale green in color, reddish-brown, dark brown, and white with red or dark stripes. In cross-section of the rice grain, the layers are very similar to those in wheat. There is the pericarp of several layers, the testa, the nucellus (perisperm), and the aleurone layer, usu- ally of one row of cells. The embryo is about one-third the length of the fruit. During the milling process, the lemma and palet, the embryo, pericarp, testa, nucellus, and in many cases all or a portion of the aleurone layer are removed. This "scouring process," in the case of Honduras and Japan rices, removes about 10 per cent, of the weight of the grain, and a considerable quantity of ash, fat, crude fiber, protein, and pentosans. The color of red rice is located in the seed coat, or throughout the endosperm. Milling of Rice. — The threshed rice from the field is called "paddy rice." The grains are enclosed by the glumes, lemma, and palet, which together constitute the "hull." The hulls are removed by passing the grains between revolv- ing millstones, set apart about two-thirds the length of a rice kernel. The hulls are then removed by a fanning device, and this process followed by the separation of the rough (un- hulled) from the clean rice in the "paddy machine." The next process removes a part of the bran layer (pericarp, testa and nucellus) and most of the embryo. After a separation of the powdery bran from the cleaned rice, the grains are then led into the "pearling cone" where they are scoured. This is followed by a thorough pohshing between pieces of pigskin. The grains then receive a coating of glucose and talc, and are ready to be graded and packed for the market. 2o6 BOTANY OF CROP PLANTS Beriberi. — This is a disease resulting from a diet consisting ' chiefly of polished rice. Asiatic laborers who have been fed upon polished rice develop this disease, while, if the rice is not polished, the disease does not appear. When rice is polished, there is removed a large proportion of the phosphates of the grain, and hence, when rice is almost the sole food, there is a deficiency of phosphates in the ration, which lack results in the disease, beriberi. Of course, those who have a mixed diet get the requisite amount of phosphates from a number of different foods, and hence may eat polished rice without any ill effects. Varieties. — Carleton gives the following provisional ar- rangement of wild and cultivated rices: 1. Oryza granulata (wild rice). 2. Oryza officinalis (wild rice). 3. Oryza sativa (cultivated rice). (a) utilissima. 1. communis (large-kerneled rice). 2. minuta (small-kerneled rice). (b) glutinosa (glutinous rice). American varieties are comparatively few in number. Three main types are grown: Honduras, CaroHna and Japan. The hulls of Honduras and Japan rice are yellowish-brown, those of Carolina rice mostly a golden yellow. Lowland types of rice form, almost exclusively, the sorts grown in this country. Japan rice has smaller grains, a thinner hull, and tillers more than the other types in the United States. Honduras and Carolina belong to the communis group, and Japan to the minuta group. Distribution and Closely Related Species. — There is is a great number of Oryza species found growing wild in tropical regions of both hemispheres. The native home of O. sativa is the warm parts of Asia and Africa. Culti- vated rice probably originated in eastern Asia. In this country, there are two quite common native plants termed "rice." These are, Canada rice {Zizania ORYZA SATIVA 207 aqualica), and ivild rice {Zizania miliacea). Both are tall aquatic grasses belonging to the same tribe (Oryzea,') as cultivated rice. Both species of Zizania differ from Oryza in having monoecious spikelets. Uses of Rice. — Rice is a food for more human beings than is any other grain. It is the principal food of the densely populated regions of China, India, and the neighboring islands. The consumption of rice per capita in the United Fig. 77. — Harvesting rice in Arkansas. {From Essentials of Geography , Second Book. Copyright 19 16, by Albert Perry Brigham and Charles T. McFarlane. American Book Company, Publishers.) States is steadily increasing. Orientals do not polish their rice, while all the rice that comes on the market in this coun- try has had the hull removed, and has been polished. Rice hulls and rice flour or polish, removed in the miUing process, are used as stock food. Rice straw is also used as a food for stock, and in the manufacture of paper, straw hats, straw board, etc. In Japan, a drink called "sake," similar to beer, is made from rice. BOTANY OF CROP PLANTS Environmental Relations. — Rice has a climatic range simi- lar to that of cotton; it is seldom raised north of that region in which the average summer (June, July, August) tempera- ture is lower than 77°F. It reaches its best development in moist regions. Certain sorts of upland rice are planted, cultivated and harvested like oats. But, most of the rice ORYZA SATIVA 209 is raised on low delta or alluvial lands that will permit of inundation. In lowland rice culture, flooding of the field is usually resorted to in order to hasten germination; after the plants have attained a height of several inches, from 3 to 6 inches of water are turned on to the field and kept there continuously for twenty, thirty, or more, days, de- pending upon the region. The water is renewed occasionally to prevent it from becoming stagnant. It is drained off just prior to the ripening of the grain. ' The Production of Rice. — British India produced 62,- 638,912,000 pounds of rice in 1914. During the same period, Japan raised 17,826,240,000 pounds, Java and Madura (1913) 7,951,049,000 pounds, Korea 3,678,878,000 pounds, the Philippine Islands 1,403,516,000 pounds, Italy 741,263,- 000 pounds, and the United States 656,917,000 pounds. There are four commercial rice-growing districts in the United States: (i) The Carolina district, (2) the Texas- Louisiana district, (3) The Arkansas district, and (4) the California district. The heaviest producer is the Texas- Louisiana district. Louisiana produced 13,714,000 bushels of rice in 191 5, or about one-half of the total product for the entire United States. Texas ranked second with 7,930,000 bushels, Arkansas third with 4,840,000 bushels, and Cali- fornia fourth with 2,268,000 bushels. References Akkmine, M.: On the Flowers and Flowering of O. sativa. Agric. Gaz. Nogyo-Sekai, 1910-11. Graham, R. J. I).: Preliminary Note on the Classification of Rice in the Cen- tral Provinces. Mem. Dept. Agr. in India, Bot. ser. 6, No. 7: 209-230, 1913- Hector, P. G.: Notes on Pollination and Cross-fertilization in the Common Rice Plant, Oryza sativa, Mem. Dept. Agr. in India, Bo't. ser. VI, i: i-io, 1913. KiKKAWA, S.: On the Classification of Cultivated Rice. Imp. Univ. Tokyo, Coll. Agr. Bull. Ill, No. 2, 11-108, 191 2. 14 CHAPTER XVII MILLET The term millet does not refer to a definite botanical group (species, genus, or tribe) of plants. Originally it applied to certain species of grasses belonging to the genera ChcBtochloa (Setaria), Panicum and Echinochloa, which are still spoken of as the "true millets." Agriculturally speaking, the word "millet" embraces a number of annual cereal and forage grasses which have comparatively small seeds, abundant foliage, and a fibrous root system. They are raised in Europe and the United States for forage Durposes and in a number of Asiatic and African countries for human food as well. Most of these millets belong to the four genera ChcBtochloa, Echinochloa, Panicum, and Pennisetum, of the tribe Paniceae. Ragi or finger millet {Eleusine coracana) belongs to the tribe ChloridesE. It is grown in India to quite an extent as a cereal but has never attained favor in the United States. Key to Principal Economic Types (Species) of Millet and Some Closely Related Common Weed Grasses ^ Inflorescence paniculate; no involucre below the individual spikelets. Inflorescence a raceme of short spikes; empty glumes awned or awn- pointed, Echinochloa (Barnyard millets and wild barnyard grass). Awns long; spikelets white. E. crusgalll (common barnyard grass). Awns short; spikelets brown, E. frnmenlacea (Japanese barnyard millet). Inflorescence a drooping panicle; empty glumes not awned, Panicum miliaccum (proso or broom-corn millet). ' After Frear. 210 MILLET 211 Inllorescence spicate; involucre of bristles below each spikelet. Grain enclosed in lemma and palel (the hull) at maturity; spike loose, Clicelflchloa (foxtail millet and foxtail grass). Panicle usually i centimeter thick or less; bristles commonly green; spikelets about 2 millimeters long, C. viridis (green foxtail). Panicle usually i to 3 centimeters thick; bristles usually purple; spike- lets, 2.5 to 3 millimeters long, C. italica (foxtail millets). Grain globose, forcing open the hull as it matures, and falling free when threshed; spike dense, Penniselum glaucum (pearl millet). PENNISETUM GLAUCUM (Pearl Millet) Stem. — The plants are erect, and from 3 to 8 feet tall. The culms are cylindrical and pithy; the upper internodes are smooth, the upper nodes either smooth or short-hairy. Leaf. — The leaf sheaths are open and hairy; the ligule is short and fimbriated; the leaf blade is lanceolate, long-pointed, and long-hairy especially on the upper side. Inflorescence. — This is a close cylindrical spike (Fig. 79), 6 to 14 inches long and ^^ to i inch thick. The main axis is stiff and thick-hairy. The side branches are hairy, 7 to 8 millimeters long, and bear each one to three (commonly two) spikelets, which are surrounded by a cluster of bristles. These bristles fall with the spikelets at maturity. Spikelet and Flower- — The lower glume is short, broader than long, and truncate; the inner glume is longer, about one-half the length of the spikelet, oval, and three- to four- nerved. Each spikelet has two flowers, the lower stami- nate, the upper perfect. The lemma of the lower staminate flower is oval, and three- to four-nerved; the palet is small, sometimes entirely lacking, the stamens three in number, and lodicules absent. The staminate flower in the spikelet often has both palet and stamens lacking, and in some instances the spikelet has but one flower, the staminate one being en- tirely lacking. In some few instances, spikelets contain two perfect flowers. The lemma of the fertile flower is oval, 212 BOTANY OF CROP PLANTS pointed, and five- to six-nerved; the palet is oval, rounded above, pointed, and thin-membranous; lodicules are absent; there are three stamens; the ovary is obovate, smooth, and with two style branches. Pollination. — Pearl millet is regularly cross-pollinated. The flowers near the middle of the inflorescence are the first Fig. 79. -Millets. I, Common; 2, Hungarian; 3, Siberian; 4, Golden Won- der; 5, Japanese Barnyard; 6, German; 7, Pearl. to open. The stigmas of perfect flowers first appear be- tween the closed glumes, then the stamens, which are in turn followed by the appearance of staminate flowers. Mature Grain. — The kernel is 3 to 4 millimeters long, reach- ing the length of the glumes, obovate, somewhat flattened on MILLET 213 the sides, and smooth. One layer of aleurone cells is present. The kernel is easily separated, as a rule, from the lemma and palct. Varieties.— There is considerable variation in length and thickness of the inflorescence, color of inflorescence, and color of grain. No varietal classification has been made. Pearl millet is sometimes sold under the name of ^^ Pencilaria^' (Penicillaria) or Mand's Wonder Forage Plant. There are many common names for Pearl millet, some of which are cat- tail millet, African millet, Indian millet, Egyptian millet, horse millet, and Japan millet. Origin. — The wild form from which pearl millet has come is unknown. It is probable that tropical Africa is its native home. PANICUM MILIACEUM (Proso, Hog or Broom-corn Millet) Fig. 80. — Leaf of proso millet (Panicum milia- ccum). X 2. Stem. — The plants are erect, some- times decumbent at the base, and often reach a height of 3 to 7,14 feet. Branches frequently arise from the basal nodes, and they may bear inflorescences. The culms are cylindrical, and rough-hairy or smooth below the nodes. Leaf (Fig. 80). — The leaf sheaths are open. They are covered with very small protuberances (papillae) from each of which arises a stiff hair; at the sheath nodes the hairs are shorter and not mounted upon papillaj. The ligule is short, thick, and fimbriated, and the auricles are lacking. The leaf 214 BOTANY OF CROP PLANTS blade is linear lanceolate, and hairy, especially upon the upper surface. Inflorescence.- — This is a rather dense panicle (Fig. 8i), 4 to lo inches long; the erect or ascending branches are some- FiG. 8i. — Inflorescence of proso millet (Panicum miliaceum). what angled and rough with short hairs that point forwards. In some varieties, the branches of the panicle spread to all sides, in others they are more or less compressed and one- sided, while in a few varieties, the panicle is much compressed, thick, and erect. MILLET 215 Spikelet and Flower. — The spikelets are oval in shape and 4/^ to 5 mm. long. The lowermost glume is broad, pointed, five- to seven-nerved, and about one-half the length of the spikelet; the second glume is the length of the spikelet and bears 13 nerves. Within the second (longer) glume is the lemma of a sterile flower; this lemma is slightly shorter than the glume surrounding it, and encloses a very small palet. Above this sterile flower, is a perfect one. The lemma of this is parchment-like, broad, and seven-nerved; it encloses the three-nerved palet. The two lodicules are fleshy, smooth, and somewhat broader than long. Stamens are three in number. There are two plumose style branches. Pollination. — This millet is quite regularly cross-polli- nated; however, self-pollination is not excluded. Mature Grain. — The kernel is firmly surrounded by the indurated, shining lemma and palet. The whole grain measures about 3 millimeters in length and 2 millimeters in width. The kernel itself is broadly oval, smooth, white, and does not possess a groove or furrow as does wheat. The position of the embryo is indicated by a shallow broad marking about one-half the length of the kernel. The wall of the kernel is thin. There is one row of small, flat aleurone cells surrounding the starchy endosperm. Varieties. — Koernicke recognizes three main types of broom-corn millet. These are as follows: 1. Panicum miliaceum efusiim. — Panicle broad, the branches spreading to all sides. 2. Panicum miliaceum conlractum. — Panicle less spread- ing than preceding, one-sided. 3. Panicum miliaceum compactum. — Panicle compact, thick, and erect. Origin. — The native home of Panicum miliaceum is not 2l6 BOTANY OF CROP PLANTS known. The plant has been cultivated in Europe and Asia from the earliest times. CHiETOCHLOA ITALICA (FoxtaU Millets) Stem. — The plants are erect and from 2 to 5 feet tall. The culms are cylin- drical; they may branch near the base, but such branches seldom produce flowers and fruit. Leaf. — The leaf sheaths are open, and smooth or hairy. The ligule is short, thick, and fimbriated; auri- cles are absent. The leaf blades are long, broad, and taper to a sharp point. Inflorescence. — The spikes (Fig. 79) are 4 to 9 inches long, and ^2 to 2 inches thick. The chief axis of the inflorescence and the short side branches are hairy. On the short lateral branches, there occur bristles (Fig. 82) subtending the spikelets. These bristles bear short hairs that point forward. There is evidence that they are abortive branches. It has been noted that varieties apparently without bristles, occasionally bear spikelets with bristles. sterile flower i bristles Fig. 82. — Spikelet of foxtail millet (Chaetochloa italica). X i5- MILLET 217 Spikelets and Flower.^ — The spikelets are elliptical, and usually shorter than the bristles, which subtend them. Each spikelet (Fig. 83) has two flowers, the lower ster- ile, the upper with both stamens and pistil. The lower- most glume is oval, pointed, three-nerved, and about one- third the length of the spikelet. The second glume is five-nerved, and slightly shorter than the spikelet; it sur- rounds the lemma of the sterile flower. The lemma of the fertile flower is broad-oval, and five-nerved; the palet is about the same length as its lemma. Both lemma and lemma 1^ . . r__- glume sterile flower iertile flower Fig. 83. — Dissected spikelet of common millet (Chaitochloa italica). X lo palet of the fertile flower are smooth, shining, hardened structures. The lodicules are fleshy. There are three stamens. The ovary is long-oval and smooth; its style has two long branches, with the rudiment of a third. Pollination. — Cross-pollination is the rule; self-pollination occasionally occurs. Mature Grain (Fig. 84). — The lemma and palet enclose the mature kernel. The grain is oval, shining, 2 to 2}-^ milli- meters long and il^it to 1^2 millimeters wide. The kernel is broad-oval, smooth, and white; it does not have a groove or furrow. The position of the embryo is indicated by a mark 2l8 BOTANY OF CROP PLANTS which is about one-half the length of the kernel. The peri- carp is thin. There is a single row of small, flat cells in the aleurone layer. T3^es and Varieties of Foxtail Millet.^ — ^Koernicke rec- ognizes two main groups of cultivated millets belonging to the species Chcdtochloa italica: Fig. 84. — A, grain of foxtail millet (Chatochloa italica) with lemma and palet attached; B, grain of same, embryo side with "hull" removed; C, grain of same, side opposite the embryo; D and E, grains of pearl millet (Pennisetum spicatum). X 10. I. Chcetochloa italica maximum. — Heads long, open, and drooping. This group has two subdivisions: (i) varieties with short bristles, and (2) varieties with long bristles. Here would be included Aino millet, German mil- let, Golden Wonder millet, and Siberian millet. MILLET 2IQ 2. ChcBtochloa italica moharium. — Heads short, thick, erect, or drooping but very slightly. This group also has two subdivisions: short-bristle and long-bristle varieties. Here belongs Hungarian millet. Key to Principal Typks of Foxtail Millets (Ciletochloa italica)^ Heads small, uniform, compact, seeds yellowish to black with usually a large percentage very dark; beards brown or purple, Hungarian Alillcl. Heads large, more or less open; seeds more or less bunched. Heads long, slender, very open, lax, drooping; seed groups very distinct, Ahio Millet. Heads shorter and plumper, bushy, erect or slightly drooping; seed groups indistinct. Seeds yellow. Profusely bearded; medium large heads. Heads large, seeds small, seed groups more distinct, German Millet. Heads small, seeds large, seed groups less distinct, Common Millet. Sparingly bearded; heads very large, Golden Wonder Millet. Seeds red or pink, Siberian Millet. Origin of Foxtail Millet. — The stem form of the foxtail millets is Chcclochloa viridis, the green foxtail. It differs from the cultivated forms in that its fruit falls from the inflorescence when mature. Chcstochloa viridis is a native of the Old World. It is now found in waste places in North America from Texas to Quebec. ECHINOCHLOA CRUS-GALLI (Barnyard Grass or Barnyard Millet) Habit, Stems, Leaves. — This grass is an annual, 2 to 4 feet tall ; the culms often branch at the base. The leaves are 3 2 to 2 feet long, 3<^ to i inch wide, and have smooth, glabrous sheaths and smooth or scabrous blades. Inflorescence, Spikelet, Flowers, and Fruit.^ — The inflores- cence is a panicle made up of from five to fifteen sessile, erect or ascending branches; the lower branches may be spreading 1 After Frear. 220 BOTANY OF CROP PLANTS or reflexed. The spikelets are ovate, green or purple, and densely crowded in two to four rows on one side of the rachis. Each spikelet has two flowers: a lower staminate, and an upper perfect. Within the two empty glumes is the lemma of the staminate flower; then follow the lemma and palet of the perfect flower, both of which are hard and parchment-like in texture. The lemma of the staminate flower is awned, that of the perfect flower abruptly pointed. There are three stamens, and two plumose stigmas. The kernel is firmly surrounded by the hardened lemma and palet. Distribution. — Barnyard grass is a native of Europe. It is now widely distributed as a weed in cultivated soil and in waste places. ECHINOCHLOA FRUMENTACEA (Japanese Barnyard MUlet) In general characters, Japanese barnyard millet corre- sponds very closely to common barnyard millet, except that in the main, it has a more nearly erect habit, more turgid seeds, is awnless, or has very short awns, and is brown or purplish in color. It is known as Sanwa millet in India, and "bilHon- dollar grass" in the United States. It probably originated from common barnyard millet {E. crusgaUi). Environmental Relations.- — The millets require environ- mental conditions similar to those favoring sorghums. They are sensitive to cold, and hence must be planted after all danger from frost is over. The water requirement of millets, as a group, is less than that of sorghums. Hence they are among our most drought-resistant crops, and on this account, have been cultivated extensively on the Great Plains, from Kansas to Dakota. Uses of Millets. — The millets are grown as a hay crop, for pasturage purposes, and for the seeds, which are most commonly fed to poultry. Millet is a quick-growing crop. MILLET 221 and is ready to cut for hay in from six to ten weeks after seed- ing. The foxtail millets are more valuable for hay than the prose group. The latter is most frequently grown for the grain. References Ball, Carleton R.: Pearl millet (Pennisctum spicatum). U. S. Dept. Agr. Farmers' Bull. i6S: 1-16, 1903. CHAPTER XVIII PHLEUM PRATENSE (Timothy) Description. — Common timothy is a perennial grass, from T-}i to 5 feet high. Corms or bulbs form in the lower leaf axils, a single seedling sometimes having from eight to twenty. These bulbs develop in the fall of the year, hve through the winter, and send up new shoots the following season. Thus we see that the plant reproduces vegetatively as well as by seeds. In cultivation the plant shows marked variation in stem, leaf, and inflorescence characters, in earhness, duration of bloom, longevity, vigor, stooling power, disease resistance and yield of hay and seed. The leaves are flat, and three to eight per stem; the upper sheaths are long, usually exceeding the internodes, and slightly inflated; the ligule is rounded. The inflorescence is cylindrical and spicate; although it is often called a spike, it is in reality a contracted panicle. The s pikelets are one-flowered. Each spikelet is subtended by two membranous, compressed glumes which are ciliate on the margins (Fig. 85), truncate at the tip and awned ; the lemma is much shorter and broader than the glumes, thin, truncate, and finely toothed at the apex; the palet is narrow and thin. Stamens are three in number. There are two distinct styles with plumose stigmas. The whole process of blooming and dehiscence of anthers takes place in about one and one-half hours. Clark observed that the average number of days the individual heads remain in bloom varies from seven to ten. The upper third of the head blooms first. The time of bloom- ing is just before daybreak. The egg-shaped grain is enclosed PHLEUM PRATENSE 223 by the lemma and palct. Self-fertilization usually occurs in timothy, although cross-fertilization may also take place. It is customary to cut timothy while it is in bloom or just past bloom, for at this time the yield of dry matter is greater than at any other stage of maturity. This is due to the loss of leaves and the movement of food materials to the roots which follow the blooming period. Fig. 85. — Timothy (Phleum pratense). A, single spikelet; B, spikelet with glumes removed; C, pistil. Environmental Relations. — Timothy thrives best in a moist and cool climate; it is not grown south of the 36° latitude, except at high elevations. It is unable to endure hot, dry summers, such as exist in the Great Plains and intermountain areas. It is an important crop at high altitudes in the Rocky Mountains, where it is usually mixed with Alsike clover. It will grow on both clay and loam soils, and does best when lime is present. Closely Related Species. — Mountain timothy {Phleum alpinnm) is common in meadows from Labrador to .\laska, in the mountains of both the East and the West, also Europe, Asia, and temperate South America. The inflores- 2 24 BOTANY OF CROP PLANTS cences are much shorter than those of common timothy, the awn is about one- half the length of the outer glume, and the upper leaf sheath is inflated. • References Clark, Charles F.: Variation and Correlation in Timothy. Cornell Agr. Exp. Sta. Bull. 279: 1-350, 1910. Observations on the Blooming of Timothy. Plant World, 14: 131-136, 1911. Webber, H. J.: The Production of New and Improved Varieties of Timothy. U. S. Dept. Agr. Bur. Plant Ind. Bull. 313: 339-381, 1912. CHAPTER XIX SACCHARUM OFFICINARUM (Sugar Cane) Habit, Roots. — Sugar cane is a tall, perennial plant, re- sembling corn and the sorghums in general habit. The root system is fibrous and rather shallow. Stems.- — The stem is of the usual grass type — divided into a number of joints. The cylindrical, solid culm is 8 to 15 feet high, and i to 2 inches in diameter. There are sometimes as many as 60 to 80 nodes. The jointed stem is prolonged into the ground, and the roots arise from the lower- most nodes. This stem arises from the rootstock of the pre- vious year, or, under artificial conditions, from the planted portion of a cane. The buds are found, as usual, in the leaf axils. They are better developed in the lower leaf axils than in the upper. Around the culm, at the bud, are several rows of dots; roots arise from these dots when the cane is planted, or when in any way it is brought into contact with the soil. Sugar cane "suckers" readily. The plant is propagated entirely from stems. The whole stalk may be used or only the lower parts of the stools, the so-called "rattoons." Leaves. — There is a single, broad, clasping leaf at each node. Inflorescence, Flowers, Fruit. — The inflorescence is a loose panicle, i foot or more in length, with numerous branches. The spikelets are arranged in a racemose fashion on slender branches. They occur in pairs, one of which is pedicellate, the other sessile. There are two glumes at the base of the 2 26 BOTANY OF CROP PLANTS spikelet. Each spikelet is two-flowered; the lower one is sterile and consists of a palet; the upper is fertile and has a lemma and palet, two minute lodicules, one to three sta- mens, and a single ovary with two stigmas. There is a tuft of long, silky hairs at the base of each spikelet. The grain Fig. 86. — Mill where sugar cane is crushed. {From Essentials of Geography, Second Book. Copyright, 1916, by Albert Perry Brigham and Charles T. McFarlane. American Book Company, Publishers.) is small, silky, and of low vitaHty. Mature grains are seldom produced in cultivated plants and pollen is often infertile. Geographical. — Saccharum officinarum is a native of the tropics. It is now grown as a crop throughout our Southern States and in many other warm regions. It is not a success SACCHARUM OFFICINARUM 227 north of the latitude of 3,^5°. The roots are unable to stand a temperature much lower than i5°F. Sugar from Sugar Cane.^The canes, stripped of their leaves, are first shredded by revolving spiked cylinders, and then passed between three different sets of rollers, which crush out the juice. About 75 per cent, of the juice is pressed out by the first set of rollers. Between the first and second set of rollers, the canes are sprayed with the heated juice from the third set. About 10 per cent, of the total amount of juice is removed by the second set of rollers. Before reach- ing the last set of rollers, the crushed material is sprayed with hot water; in this process about 5 per cent, of the total juice is removed. The crushed canes, known as "bagasse," are utihzed as a fuel to run the mill. The juice that flows from the rollers is turbid, due to the impurities which it contains. It is strained, and then milk of Hme is added. The Kmed juice is heated with steam. The impurities unite with the Hme, and appear as scum on top or as a sediment at the bottom of the purified juice. The clear juice is run into vacuum evaporators, where it is concentrated to the desired point. The concentrated juice is then pumped into tanks, where crystaUization is brought about. The grain of the sugar is under the control of the one who has the crystallizing pans in charge. A high temper- ature in the vacuum pans favors the formation of hard- grained sugar; while a low temperature and high vacuum produce a "soft sugar." The mixture of molasses and sugar crystals is termed "massecuite." They are separated by centrifugal action. The sugar crystals are then dried, and packed for shipment. By-products of Manufacture. — Cane molasses from the manufacture of white and high-grade yellow sugars is used for 2 28 BOTANY OF CROP PLANTS baking purposes and as a table syrup. Poorer grades are employed in rum and alcohol manufacture, and in stock feeding. Mention has been made of the fact that the stalks from which the juice has been removed are used as a fuel to run the mill. The refuse that accumulates in the purification process is used as a fertilizer. It is rich in phosphorus and potash. Production of Cane Sugar.- — The world's production of cane sugar during the 1913-1914 campaign was 11,225,000 short tons (excluding Central America). During the same period, the world production of beet sugar was 9,430,145 short tons. Sugar-cane production in the United States is confined almost exclusively to southern Louisiana, and to Texas, immediately adjoining. Leading Countries in the Production of Cane Sugar, 1913-1914 Country Short tons Cuba 2,909,000 British India - 2,566,000 Java 1,541,000 Hawaii 612,000 Philippine Islands • . . . . 408,000 Australia and Fiji 407,000 Porto Rico 364,000 Argentina 304,000 United States 301,000 Mauritius 275,000 CHAPTER XX LILIACE^ (Lily FamUy) Representatives of the lily family are found all over the world, although the family is best developed in drier parts of the temperate zone. The family is by no means of as great economic importance as the grass family. A number of representatives are cultivated as vegetables, the principal ones being onions and asparagus. Yucca, lily (Lilium), hyacinth and tulip are chief among those cultivated as ornamentals. Habit, Roots. — Most members of the family are fleshy herbs from bulbs or rhizomes. Some species of Aloe and DraccBna, however, are shrubs or small trees. In herbace- ous forms, the roots are mostly fibrous and shallow, sometimes fleshy and extending to considerable depths in the soil. Stems. — Both underground and aerial stems are borne. Underground stems in the family are either rhizomes or bulbs. The character of rhizomes has been described (page 29). Bulbs are fleshy stems with a very short, usually con- ical stem upon which are many fleshy, overlapping leaves (Fig. 14). Bulbs, hke rootstocks or rhizomes, are storage organs. They are made use of in vegetative propagation. The aerial stems may be leafy or free of leaves for a long dis- tance. In Yucca — the soapweed or Spanish bayonet — of the semi-arid sections of the country, the base of the aerial stem is persistent from year to year. Leaves. — The leaves arc mostly linear, seldom divided or toothed, and not divided into petiole and blade. 229 230 BOTANY OF CROP PLANTS Inflorescence and Flowers.- — There are a number of different types of inflorescences in the family. The flowers are often single or solitary, as in the lilies; or racemose, as in the soapweed and hyacinths; or umbellate, as in onion. The umbellate or umbel-like type of inflorescence consists of many flower stalks of about equal length arising near together on the stem; the outside flowers open first, the inside last, that is, the order of opening is centripetal. This is the order of opening in all racemose types of inflorescences. The perianth con- sists of six separate segments, in two whorls of three each, which are very similar in size, shape and color (Figs. 3 1 and 87) . The stamens are attached to the receptacle or to the perianth. The anthers are usually large and con- spicuous. The superior ovary is three-celled, has one style and a three-lobed stigma. Fruit and Seeds. — The fruit is a capsule or berry. The capsule is a dry, sphtting (dehiscent) fruit with several united carpels. When the carpels spht down the middle line as they do in lilies, the dehiscence is said to be loculicidal. It is distinguished from septicidal dehiscence of capsules, in which the carpels open along the line of their union, as in rhododendron, and from poricidal dehiscence in which the carpels open by pores, as in the poppy. The berry is a fleshy fruit possessing several to many seeds which are more or less imbedded in the fleshy ovary wall (pericarp). The seeds always possess abundant endosperm, which en- closes the embryo. Considerable quantities of oil occur in the endosperm. Fig. penanih 87. — Flower of onion (Allium cepa). LILIACE^ 231 ALLIUM To this genus belong chives, garUc, leek, onion, shallot and Welsh onion. Thev are all herbs with a characteristic Fig. 88. — A, Welsh onion (Allium ascolonicum) ; B, cive (Allium schceno- , prasum). alliaceous odor, which is due to the presence of all\l sulphide. 232 BOTANY OF CROP PLANTS Roots. — The root system is fibrous and very shallow (Fig. 88). The roots arise from the reduced stem, forming a fibrous tuft. Stems. — With but few exceptions, species of the genus Allium bear bulbs. In chives {Allium schcenoprasum), the bulbs are very small (Fig. 88), and in Welsh onion (Allium fistulosum) and leek {Allium porrum), they are nearly always Fig. 89. — Leek (Allium porrum). absent (Figs. 88 and 89). In the common onion {Allium cepa), they are large and well developed. Examination of the mature bulb of the common onion shows it to be made up of the much thickened bases of leaves, attached to a compara- tively small, conical stem (Fig. 14). This is best seen in a median, longitudinal section. From a terminal bud on this small, underground stem, there is sent up a long hollow or solid, leafless stem (Fig. 90) (scape) bearing an inflorescence at the top, which in this case is an umbel. Lateral buds are LILIACE^ 233 sometimes borne in the axils of the leaves, and these may also develop into flower shoots. Leaf.- — The first foliage leaf emerges from a slit in the cotyledon. All leaves are very thick and fleshy, and over- lapping. There is no petiole. The oldest leaves are on the Fig. 90. — ,4, base of stem of common onion (Allium cepa) showing hollow leaves cut across; B, cross-section of hollow stem of same: C, t^ase of stem of leek (Allium porrum) showing flattened solid leaves; D, cross-section of solid stem of same. outside of the bulb, while the younger appear toward the inside. In a longitudinal section of the bulb, it will be noted that these younger leaves, coming from within, are higher on the compressed stem than the older (Fig. 14). The edible portion of the common onion, and of some other 234 BOTANY OF CROP PLANTS species, is the fleshy bases of leaves. In some species, as leek and shallot, the leaves are used as a seasoning in food. The leaves may be either flat or cyhndrical (terete), and are sometimes hollow. Onions have been known to bear buds (epiphyllous buds) on their leaves. Inflorescence (Fig. 91).^ — The numerous flowers are in simple, terminal umbels. The umbel is subtended by a jim^ i i f f ^ Fig. 91. — Umbel of onion (Allium cepa). spathe, consisting of two (rarely three) papery bracts. The spathe encloses the entire umbel in the bud. The pedicels are long and slender. Flower.^ — The flowers (Fig. 87) are regular and perfect. The perianth consists of six distinct segments which are very similar as to size, shape and color. The six stamens are inserted on the bases of the perianth segments. Alternate LILIACE^ 235 lilamcnts arc usually dilated at the base, and the anthers are oblong, and opening inward (dehiscing inward). The single, superior ovary is imperfectly three-loculed and bears a C Fig. 92. — Seed and seedling of onion (Allium cepa). A. seed; B, to F. suc- cessive stages in the development of the seedling; c, cotyledon; e, endosperm; /, first true leaf; h, hypocotyl; s, slit from which the first true leaf emerges. A considerably magnified. {After Bergen and Caldwell.) single filiform style, which may be more or less indistinctly three-cleft at the apex. Pollination. — Species of Allium are insect pollinated. The anthers of the flower usually mature before the stigma, al- 236 BOTANY OF CROP PLANTS though the reverse is sometimes the case. The inner circle of stamens is the first to shed pollen. Fruit.^ — This is a three-celled, membranaceous capsule with loculicidal dehiscence. Two seeds, black in color, are usually borne in each locule of the capsule. The seeds (Fig. 92) are convex on one side and almost flat on the other, and possess a large quantity of oil. The embryo is cylin- drical and curved. Germination of Seed, and the Seedling. — At the beginning of germination, the primary root is forced out by the' growth of the curved end of the embryo (Fig. 92). The curved end of the embryo, the cotyledon, comes out of the ground in the form of a closed loop. The tip of the cotyledon re- mains attacked to the endosperm and seed coat. When the soil is loose, the endosperm and seed coat may be pulled from the ground, but in case it is compact, they remain beneath the ground. The cotyledon absorbs nourishment from the endosperm. When this is used up, the cotyledon tip withers and becomes detached from the seed coat. At the base of the cotyledon, where it joins the hypocotyl, there early appears a longitudinal sht; through this, the first foliage leaf emerges. The cotyledon later disappears entirely. Geographical. — There are about 250 species of the genus Allium, .the majority of which occur in boreal America, Mexico and northern Europe. A number are also found in Abyssinia and extratropical Asia. The cultivated onions require cool, moist weather during the early stages of their development, but ripen better if the weather is drier. Key to Principal Cultivated Species of Genus Allium Leaves flat and solid (Fig. 90). Leaves keeled, very narrow, Allium sativum (garlic). Leaves keeled, very broad, Allium porrum (leek). LILIACE^ 237 Leaves cylindrical and hollow (Fig. 90). Plants forming a dense clump with very small bulbs, Allium sclneno- prasum (cive or chives). Plants not forming dense clumps; bulbs of considerable size. Leaves short, awl-shaped; bulbs in clusters (Fig. 88), Allium ascaloni- cum (shallot). Leaves long, rather broad; bulbs not in clusters. Bulbs very distinct, generally large (Fig. 14), Allium ccpa (common onion). Bulbs not distinct, usually a mere swelling at base of plant (Fig. 88). Allium Jlslulosum, (Welsh onion, ciboule). ALLIUM SATIVUM (Garlic) Garlic is a perennial herb. The bulbs are composed of several small, elongated, egg-shaped bulbils, called "cloves," all of which are enclosed by a whitish skin (Fig. 93). There are often as many as ten bulbils in a single bulb. The scape is from I to 2 feet high, round, and possesses alternate, broad- linear, sohd, flat leaves. The spherical umbels bear many bulblets among the small, long- stemmed flowers. Seeds and bulblets are borne in the same head. In propagation, the bulb- lets in the flower head and the cloves are used more commonly than seeds. GarHc is a native of southern Europe. Both the cloves and leaves are used in seasoning salads and soups, and the stems are also often an ingredient of sausage and other ground meats. Fk;. 93. — Bulb of garlic (Allium sativum), x H- 238 BOTANY OF CROP PLANTS ALLroM PORRUM (Leek) Leek is a very robust biennial plant. The bulbs are small. The tall scape is solid and bears broad, sohd, keeled leaves (Fig. 90). Leek is a native of the Mediterranean region. The edible portions of the plant are the bases of stems and leaves. The stems are blanched and eaten the same as aspara- gus or as common onions. The leaves are used to season soups, salads and stews. Important varieties are Large American Flag, Mussel- burgh, Large Rouen and Monstrous Caratan. ALLroM SCH(ENOPRASUM (Chives or Gives) Chives (Fig. 88) are hardy perennials bearing small, white, narrowly ovoid, clustered bulbs with membranous coats. The scape is stout and up to 2 feet high. The leaves are linear, terete, and hollow, 7 or 8 inches in length and borne in dense tufts. The rose-colored flowers are in dense, globu- lar umbels. Although the plant flowers profusely, it seldom produces seeds. It is propagated by division of the tufts of bulbs. Chives are natives of Europe, Asia and North America. In this country, they grow wild from New Brunswick to Alaska, south to Maine, northern New York, Michigan, Wyoming and Washington. The young leaves are used in the seasoning of soups, ome- lets, and stews. The plants are also used, ornamentally, in garden borders. ALLroM ASCALONICUM (ShaUot) This is a perennial herb with small, oblong-pointed bulbs about I inch in diameter and 2 inches long (Fig. 94). The LILIACE.^ 239 bulbs are borne in clusters, but unlike garlic, are not sur- rounded by a thin membrane. The leaves are short, cylin- drical and hollow. The compact umbels bear lilac or reddish flowers. Fig. 94. — Shallot (Allium ascolonicum). ALLroM FISTULOSUM (Welsh Onion or Ciboule) This is an annual or biennial with long, fibrous roots. No bulbs are produced, mere swellings occurring at the base of the plant (Fig. 88). The leaves are long, rather broad and hollow. It seeds well. The plant has been found wild about the Altai Mountains and Lake Baical in Siberia. It is not known how the plant got its name "Welsh Onion." 240 BOTANY OF CROP PLANTS The leaves are used as a seasoning in stews, soups and salads. ALLIUM CEPA (Onion) Description. — The common onion is a biennial with large bulbs, that are usually single. The scape is 2 to 3 feet tall, smooth, and somewhat enlarged near the middle. The leaves are long, broad, cylindrical and hollow (Fig. 90). Fig. 95. — Top onions. History. — The common onion is at present not found in a wild state. Its cultivation dates back to the earhest times in the history of India, Egypt, and China. It was used by Egyptians as a sacrificial offering. By 1390, the onion was quite extensively used in Europe. The earhest colonists brought the onion with them to America. LILIACE^ 241 Types of Onions. — The varieties of common onions differ quite widely as to manner of propagation, quality, shape, color and size of bulbs, and time of maturity. L. H. Bailey proposes a classification as follows: 1. Propagated by division {Allium ccpa var. miilli plicans). Potato onions. Multipliers. 2. Propagated by inflorescence bulblets or "tops" (Fig. 95) {Allium cepa var. bulbellifcni). Top onions. Tree onions. Egyptian onions. Fig. 96. — Two common types of onions based upon shape of bulb. A, globe type; B, flat type. 3. Propagated by seeds {Allium ccpa). (These are also propagated by "sets," which are small bulbs grown from seed and arrested in their develop- ment.) Skin of mature bulb silvery white. 1. Globe onions (Southport White Globe) (Fig. 96). 2. Flat onions (Fig. 96). (a) Bulbs large (White Italian Tripoli, Silver Skin, White Bermuda, White Portugal). {b) Bulbs small (Queen). 16 242 BOTANY OF CROP PLANTS Skin of mature bulb colored. 1. Globe onions (Southport, Yellow Globe, Southport Red Globe, Giant Rocco, Golden Ball, Yellow Danvers). 2. Flat Onions. (a) Bulbs deep and distinctly red (Red Wethersfield, Red Globe, Red Bermuda). (b) Bulbs indifferent in color, reddish or yellowish (Yellow Danvers, Prizetaker, Strasburg). The '^ multiplier'^ onions have compound bulbs (Fig. 97), copper-yellow in color, with rather thick skin and mild flavor. When large bulbs are planted, they segregate into a number of bulbs, and each produces six to twelve stalks. The potato Fig. 97. — Cross-section of a multiplier onion bulb. {After Bailey.) onion is a hardy "multiplier," sometimes called Enghsh multiplier. The principal use of the "multiplier" group is in the production of "bunchers" for the early market. There are both white and yellow "multipliers." In "top," "tree," and "Egyptian" onions, clusters of bulb- lets are produced at the top of the scape. Some primordia develop into flowers and others into bulblets. In some cases, all the primordia may develop into bulblets, and again, al- most all may develop into flowers, some of which may pro- duce fertile seed. Bulblets may be produced in separate clusters one above the other on the same stalk. They may LILIACE^ 243 germinate while still attached to the inflorescence. It is not clearly known what is the cause of bulblet formation in the inflorescence. Egyptian onions are often caWad'' peren- nial tree onions." They are valued for fall planting in the North to produce early spring "bunchers." They are a hardy type. The types of onions grown from seed are also classified by Goff and by Gross. In these classifications, the primary divisions are made on the basis of bulb shape, the secondary ones, on size and color. Foreign and Domestic Onions. — There is a rather sharp distinction between "foreign" and "domestic" types of onions. The foreign types include Bermuda, Spanish and Italian onions. As compared with American types, they are larger, less hardy, the flesh is more tender and mild, but they do not keep as well. On account of their tenderness, the foreign types of onions do best in Florida, Texas, and south- ern CaHfornia. Seed of the Bermuda onion is produced successfully only in Teneriffe, one of the Canary Islands, off the west coast of Africa. Attempts to grow seed in the United States have given comparatively poor results. The Prize taker is our best example of a Spanish onion. Impor- tant varieties of Itahan onions are the Barletta, White Italian Tripoh, White Rocco, and Giant Gibraltar. There are numerous varieties of American onions, well-known ones being as follows: Red Wethersfield, Southport Globe (white, yellow and red), Danvers, American Prizetaker, White Portugal, Silverskin and Strasburg. Composition of Onions. — Difi'erent varieties of onions vary as to flavor and composition. The foreign types are milder than American types. The flavor is usually more pronounced in bulbs than in leaves or other parts of the plant. The flavor and odor of onions is due to an oil-like 244 BOTANY Ot' CROP PLANTS organic compound of sulphur, allyl sulphide. The com- pound is volatile to a high degree, and is broken down by heat; consequently the onion is milder when cooked than when raw. As a rule, white varieties are milder than yellow and red kinds, although there are exceptions to this. Uses of Onions. — Onions are most commonly used as a vegetable, but in many instances for flavoring purposes. The small varieties such as Queen, Barletta, and American Silverskin are used for pickling. The Egyptian (perennial tree onion) and multipliers are valued for the production of bunchers. It is considered that the allyl sulphide in onions stimulates the flow of digestive juices and hence they are often recommended for those having a tendency to constipation. Again, on account of the small amount of starch and sugar they contain, onions are made a part of the diet of invalids who are not allowed starchy foods. ASPARAGUS Generic Description. — Members of the genus Asparagus are all perennial plants with rather fleshy roots and short rootstocks. From the latter, arise branching aerial stems, which are sometimes annual, as in the common edible asparagus (A. officinalis), or perennial as in A. laricinus, one of the ornamental asparagi. The stems are erect or climbing, in some instances {A . falcatus) reaching a distance of 25 feet or more. The small leaf-like structures along the stem, the so-called "leaves," are in reahty modified stems (cladophylls) (Fig. 98). They may be slender, as in com- mon asparagus, or broad, as in Smilax. They are arranged in clusters or whorls in the axils of the true leaves. The true leaves (Fig. 98) are scales or spines, usually very small. They subtend the branches. The flowers are solitary, in small umbels or racemes and arise in the axils of the scales LILIACE^ 245 or fascicles of cladophylls. Each flower is mounted on a very slender jointed pedicel. The perianth consists of six similar segments which are separate or slightly united at the base. They are persistent in the fruit. Stamens are --rudimentary stamenj ' -well , developed \^ U pistir ' I rudimeniarij pidtti ' I L Fig. 98. — Garden asparagus (Asparagus officinalis). A, pistillate flower; B, staminat^ flower; C, mature fruit; D, section of fruit; E and F, portions of the plant showing method of branching, position of flowers and leaves. • six in number and inserted at the bases of the perianth segments; the filaments are distinct and filiform, and the anthers are ovate or oblong, with introrse dehiscence. The superior ovary is sessile, three-lobed, with a short, slender style and three short, recurved stigmas. 7'he fruit (Fig. 98) 246 BOTANY OF CROP PLANTS is a globose berry with two seeds (sometimes more), in each of the three locules. The seeds are subglobose, often dark in color. The embryo is cylindrical. Economic Importance of Genus.^ — The genus Asparagus contains about 150 species distributed throughout tem- perate and tropical parts of the Old World. There are numerous ornamental species, the most common being Asparagus medeoloides (smilax), A. plumosus (the plumy asparagus), a climbing plant used for decorative purposes and often called "asparagus fern," and A. sprengeri, another "asparagus fern," much used for planting in hanging baskets. The only edible species of any consequence is Asparagus officinalis, the common garden asparagus. ASPARAGUS OFFICINALIS (Asparagus) The common garden asparagus is a much-branched peren- nial herb reaching a height of 3 to 7 feet. Roots.- — The roots (Fig. 99) are numerous and fleshy, ex- tending horizontally in the soil to some distance, but being confined to the surface layers. They arise both from the sides and bottom of the thickened rootstock. Each year new roots are produced and the older ones die and become hollow, without becoming separated from the stem. New roots ap- pear above the older, which accounts for the so-called "hfting" of the plants. Stems.- — Asparagus bears both subterranean and aerial stems. The underground stems are rootstocks. They are much thickened, branched, rather woody, and about as long as broad. The rootstock or ' ' crown ' ' makes an annual growth of I to 3 inches. Its extension is horizontal, taking place at one or both ends. The older portions of the rootstock gradu- ally die. The rootstocks send up aerial shoots (Fig. 99). These at first are thick and fleshy ("spears") and form the LILIACE^ 247 \ edible portion of the plant. The scales borne on these fleshy shoots are true leaves. At lenthg, the stems become much branched. The filiform cladophylls (Fig. 98) are mostly clustered in the axils of the minute scales. They perform the function of leaves, as is evidenced by their green color. From the time of seeding, it is usually four years before the rootstock is vigorous enough to allow cuttings to be made. Fig. 99. — Garden asparagus (Asparagus officinalis). A, young shoot cr "spear"; B.thick, fibrous roots and young shoots arising from "crown." However, good crops have been produced two years after seeding. The plant may be propagated by divison of the rootstocks, but the common method is by seeding. Leaf.^ — The true leaves (Fig. 98) are minute scales sub- tending the whorls of cladophylls. They do not perform leaf functions. Flower. — The flowers are small, drooping, greenish-yellow and usually solitary, but sometimes in twos or more at the 248 BOTANY OF CROP PLANTS nodes. Each flower is borne on a short, slender jointed pedicel (Fig. ico). The perianth is campanulate (bell- shaped), about 6 milHmeters long, the segments being linear Fig. 100. — Garden asparagus (Asparagus officinalis). Portion of pistillate plant in fruit, on left; and of staminate plant in flower, on right. and obtuse. The stamens are shorter than the perianth lobes. The single ovary has a short style, a three-lobed stigma and three locules. Common asparagus is dioecious — LILIACE^ 249 staminate and pistillate flowers are borne on dififerent plants. Hermaphroditic flowers sometimes occur, however. The staminate flowers (Fig. 98) are slightly larger than pistillate ones. Staminate flowers bear six well-developed stamens and a very short, rudimentary pistil. Pistillate flowers (Fig. 98) have six rudimentary stamens and a single well- developed pistil. Such flowers are practically unisexual. It has been shown that staminate plants are more produc- tive than pistillate ones. Green, in determining the relative productivness of pistillate and staminate plants, obtained the following results: Product from Fifty Plants Each, Staminate and Pistillate Fifty staminate plants, ounces Fifty pistillate plants, ounces First period, ten days Second period, ten days Third period, ten days Fourth period, ten days 1 37 ^i 104 68 266 164 203 154 Total for season 610 407 This shows a gain of the staminate plants over the pistillate plants of about 50 per cent, for the whole season, the greatest difference being in the first period. Hence, it seems to show that staminate plants are earlier and more productive than pistillate ones. Fruit production makes a greater demand for food than does the formation of stamens. It is for this reason that staminate plants are able to produce a greater growth of "spears" than pistillate ones. Pollination. — Common asparagus is insect-pollinated. The nectaries are small and concealed at the base of the perianth. Staminate flowers are first to open. 250 BOTANY OF CROP PLANTS Fruit.- — This is a red, spherical berry (Fig. 98) with three cells, each of which usually contains two seeds. The perianth is persistent in the fruit. The dark, somewhat triangular seeds run about fifty to a gram. They preserve their germi- nating power for four or live years, and may even retain their vitahty when soaked in water for a year. When two years old, the plant begins to produce seed, but the best seed is not produced until the plant is three or four years old. It is held that the best seed comes from the lower branches of the plant. Geographical.^ — Common asparagus grows wild in Europe and Asia and has escaped from cultivation in this country, often occurring as a weed in fields and along roadsides. The plant has been under cultivation for over 2,000 years. It is cultivated under a wide range of temperature conditions. Although able to withstand drought, it will not endure an extremely wet soil. Types and Varieties. — Two sorts of asparagus are sold on the market, blanched asparagus and green asparagus. Green asparagus has a more delicate flavor and is quite gener- ally considered the more desirable. Blanched asparagus has a much thicker stalk than the green sort. It must be under- stood that these two market types of asparagus are simply the result of cultural methods, and may be produced from the same variety. To produce etiolated or blanched aspara- gus, the plants are banked or ridged up with soil just as they appear above ground, so that they must make an additional growth of 4 to 10 inches before they come to light. The shoots that develop in the soil are, of course, whitish for the reason that the green coloring matter (chlorophyll) does not form in the absence of light. The number of American varieties of asparagus is small. The most common of these are Conover's Colossal, Palmetto, Barr's Mammoth, Eclipse and Columbian Mammoth White. i LILIACE^ 251 The Palmetto is grown most in the south, and is well-known on account of its resistance to asparagus rust {Puccinia as para gi) . Uses. — The common asparagus is used as a vegetable. As a rule the tender shoots are eaten fresh, but large quan- tities are also canned each year. The principal canning factories are located in California and on Long Island, New York. For canning, Conover's Colossal and Palmetto have given the best satisfaction. A method has been devised by which the soft pulp of the asparagus plant is separated from the fiber and canned in the form of a thick paste. In European countries, particularly, asparagus is dried. In this form it keeps indefinitely. References ]}.\ILKY, L. H.: Preliminary Synopsis of Onions and Some of Their Allies. Rep. of Prof, of Hort. and Landsc. Gard., 26th Ann. Rept. State Bd. Agr. Mich., Q4-98, 1887. GoFF, E. S.: Onion. 6th Ann. Rept. N. Y. State \gr. Exp. Sta., 190-214, 1887. Green, W. J.: Asparagus. Ohio Agr. Exp. Sta. Bull. 9 vol. 3 (second series), 241 : 244, 1890. Gross, A. R : American Onions. Proc. Soc. Prom. .\gr. Sci., 115-132, 1901. CHAPTER XXI HORACES (Mulberry Family) The mulberry family has about 925 species in 55 genera, occurring in tropical and temperate regions of both hemi- spheres. It possesses a number of plants of considerable economic importance. Several Asiatic species of the genus Ficus yield a sap from which rubber is made. Ficus carica is our cultivated fig. The India rubber plant of green- houses and in \Yovae?, \'& Ficus elastica. Artocar pus communis is the well-known bread-fruit of the tropics. Toxylon pomiferum is the osage orange, a tree whose wood is valuable for wheels, posts and other small articles; it is also planted for ornament. The paper mulberry {Papyrus papyrifera), is a native of Asia. Its bark is of value in paper-making. Other genera of importance are Morus (mulberry) , Humulus (hop), and Cannabis (hemp). Description. — Members of this family are trees, shrubs, or herbs with a milky sap. The huds may be naked or scaly. The leaves are petioled (stalked), stipule-bearing, and borne oppositely or alternately on the stem. The flowers are in ament-like spikes or heads on stalks which arise in the axils of leaves. An ament is a spike-like inflorescence each flower of which is subtended by a conspicuous bract. The flowers may be monoecious or dioecious. In the staminate flower, the calyx is three- to six-lobed or parted, the petals are absent, and the stamens are one to four, inserted at the base of the calyx. The filaments are thread-like, and erect or inflexed in the bud. In the pistillate flower, the calyx consists 252 MORACE^ 253 of three to five partly united sepals. The single superior ovary is one- to two-celled and bears one to two styles. The fruit is drupe-like in mulberries, an achene in hops and hem]), and a synconium in tigs. Key to Principal Genera Trees or shrubs. Flowers not in a receptacle; buds scaly, Moms (mulberry). Flowers inside of a hollow receptacle; buds naked, Picus (tig). Herbs. Erect herbs, Cannabis (hemp). Twining herbs, lliimiiltis (hop). MORUS (Mulberry) Habit, Stems.— Mulberries are trees or shrubs with milky sap and scaly bark. The branches are slender and cylindrical. The winter buds are scaly. Leaves. — The leaves are conduplicate (Fig. loi) in the bud, alternate, serrate, three-nerved, often deeply lobed, and deciduous. The stipules fall soon after development. The convolute plicate conduplicate Fig. ioi. — Three principal types of vernation. leaves on one shoot may be relatively entire, while those on another may be moderately or deeply and irregularly lobed. Inflorescences. — The flowers appear rather early in the season in the axils of the lower leaves. The staminate and pistillate inflorescences may be on different branches of the same tree (monoecious) or on different trees (dioecious). 254 BOTANY OF CROP PLANTS The staminate inflorescences are long, cylindrical catkins. They soon fall. The calyx of the staminate flowers is deeply divided into four rounded lobes. The three or four stamens are inserted at the base of the calyx, beneath the rudimentary pistil. The filaments are thread-like, inflexed in the bud and uncoil like a spring at the moment of anther dehiscence. The two-celled anthers open lengthwise and shed their pollen toward the inside of the flower (introrse dehiscence). The pistillate inflorescences are short, dense catkins. The flowers in these have a deeply four-lobed calyx, the two outer lobes being the broader. All the calyx lobes are persistent, become fleshy, and enclose the ovary in the fruit. The sessile ovary possesses one cell, and a single style divided almost to the base into two very slender, hairy stigmas. Fruit. — Each ovary develops into a nutlet bearing rem- nants of the styles at the tip and enclosed by the thickened, juicy calyx lobes. There is a single seed within each fruit. However, the mulberry "fruit" as commonly understood, is not a single drupe-like structure, as given above, but an aggregate of these, i.e., an entire pistillate flower cluster. The single fruits are very much crowded together, making up a collection, which commonly goes by the name "mulberry." Other "Mulberries."^ — The so-called paper mulberry {Papyrus papyrif era), a.nsitiYeoi eastern Asia and now planted for ornament in many parts of eastern and southern United States, may be easily distinguished from the true mulberries {Morus) by its non-edible globular fruit and the occurrence of its pistillate flowers in heads. In some sections of the country, the "flowering raspberry" {Ruhus odoralus) is confused with and often called a "mulberry." It is true that the fruit of this has some resemblance to a mulberry "fruit," but instead of bearing its single drupe-like fruits along an axis, the true drupes of the raspberry are borne on a receptacle. MORACE^ 255 The "fruit" of the mulberry is a collection of one-seeded fruits developed from a number of separate flowers in a dense inflorescence, while the raspberry "fruit" represents the matured ovaries of a number of pistils belonging to a single flower. Geographical. — The genus Morus is a native of eastern North America, higher altitudes in Mexico, Central America, Western South America, Asia, Japan, aad the Indian Archipelago. Key to Principal Species of Genus Morus Leaves smooth beneath, sometimes slightly hairy on the veins. Fruit white or pinkish; leaves becoming light green above, Morus alba (white mulberry). Fruit black; leaves becoming dark green and shining above, Morus nigra (black mulberry). Leaves hairy beneath; fruit red or purplish, Morus rubra (red mulberry). MORUS ALBA (White Mulberry) Description. — This is a low-branched tree, sometimes reaching a diameter of 2 feet. The slender, round twigs are at first hairy, later becoming light grayish brown. The leaves are light green, with prominent whitish veins, and variously lobed or divided. The staminate inflorescences are i to 2 centimeters long, slender and drooping. The pistillate ones are from 3^ to i centimeter long. The fruit is white or pinkish in color, i to 2 centimeters long, and poor in quality. Geographical. — The white mulberry is a native of Asia, probably of China. It has spread throughout Europe and has also become naturalized in eastern United States. Types and Varieties.— Economic Importance. — There are a number of types and varieties of the white mulberry. According to L. H. Bailey, the following are forms or off- shoots of Morus alba: Morus alba var. tartarica (Russian mul- berry) and Morus alba var. venosa. The Russian mulberry 256 BOTANY OF CROP PLANTS is a very hardy, low, bushy tree with small fruit which va ies in color from white to red and almost black. It is an im- portant wind-break and shelter-belt tree in the Great Plains. Teas' weeping mulberry is an ornamental variety of the Russian. Morus alba var. venosa (M. nervosa) is an orna- mental curiosity bearing jagged leaves with white, prominent veins. Morus multicaulis (M. alba var. multicaulis) was intro- duced into America in 1826 and, for a while, gave a great impetus to the attempts to grow silkworms. It is a small tree with rough, long-pointed leaves. The chief horticultural varieties of the white mulberry are: New American, Trowbridge, Thorburn and Downing. The Downing is supposed to be a variety of M. multicaulis. However, the so-called Downing of most nurserymen is the New American. Early Attempts in the United States to Grow Silk. — The white mulberry has been cultivated from the earliest times, chiefly for feeding the silkworm. In 162 1, mulberries were introduced into Virginia by the London Company with a view of establishing the silk industry in the New World. Early attempts to grow silk were made not only in Virginia but in Carolina, Georgia and Connecticut. After the Revolution, early in the 19th century, silk culture was again agitated. There existed what has been called ^'The Morus multicaulis mania." This species was introduced into America in 1826, and since it was thought to be the source of the renowned Chinese silk, soon gained wide fame here. The "craze" died down in about 1836, and since that time, there has been little effort to grow silk in North America upon a commercial scale. Uses. — As has been said, the white mulberry is the one upon which silkworms are raised. In the Old World the HORACES 257 wood of the white mulberry is used for various purposes. The roots furnish a yellow dyestuff. In western Asia the fruit is ground into a meal for food . MORUS NIGRA (Black Mulberry) Description. — The black mulberry often attains a height of 40 to 60 feet and a diameter of i to 2 feet. The numerous branches are slender, slightly hairy at first, but later become smooth and brownish gray. The leaves are dark, dull green, large, pointed at the apex, rounded or heart-shaped at the base, and the teeth rather small and close together. The sta.minate inflorescences are i to 2 centimeters long. The pis- tillate inflorescences are from 5 to 8 millimeters long. The fruil is black, i to 2 centimeters long and has a deep red juice. Geographical. — Moms nigra is a native of Asia, probably of Persia. It has become naturalized in various parts of Europe and in the United States. In this country, it occurs in the Southern States and on the Pacific Coast. Varieties. — The black mulberry has always been the prin- cipal fruit-bearing mulberry in Europe and, in an early day, in America, but it is less tender than our native red mulberry {Moms rubra), and hence has been replaced by the latter, especially in the north. The Black Persian variety of the Southern States and California belongs to this species. Uses. — Over central and eastern Asia the black mulberry is a common and rather valuable fruit, and large quantities are dried. The wood is used like that of the white mulberry. The juice of the ripe fruit has medicinal value. The fruit of all mulberries is relished by hogs and poultry, and it is the practice in some localities to plant mulberry trees along fences enclosing pastures or poultry yards. 17 258 BOTANY OF CROP PLANTS MORUS RUBRA (Red Mulberry) Description. — This is the largest of the mulberry trees, reaching a height of 60 feet and a diameter of 5 to 7 feet. The twigs are slender, dark green, with a reddish tinge, but finally become dark brown. The leaves are large, those on young shoots deeply lobed, and with oblique and rounded sinuses, in the bases of which there are no teeth; they are rounded or heart-shaped at the base, singly or doubly toothed or three-lobed, and with a rough upper surface and a soft lower surface. The staminate inflorescences are slender and cylindric. The pistillate inflorescences are much shorter than the staminate ones. The fruit is bright red, becoming nearly black, sweet and juicy, and about i centimeter long. Geographical. — The red mulberry is a native of North America. It grows from Massachusetts to southern Ontario, Michigan, and southeastern Nebraska, eastern Kansas and southward to Florida and Texas. It is most abundant and reaches its largest size in the Central States. Varieties and Uses. — There are a number of varieties of the red mulberry, all of which are more hardy than those of the black mulberry. The principal horticultural varieties are Hicks, Johnson and Stubbs. The wood is used for posts and fencing, but finds its greatest usefulness in the making of shoe lasts, churns and cooperage material. HUMULUS (Hop) HUMULUS LUPULUS (Common Hop) Root. — The root system of the common hop plant is large as compared with above ground parts. This holds true in both young and old plants. The roots extend to consider- able depths in the soil and also spread horizontally in the sur- face layers. They give rise to a fine network of small rootlets. Older roots become covered with a reddish-brown bark. MORACE^ 259 Stems. — The common hop is a perennial, herbaceous, climbing plant from an underground stem, a rootstock. These rootstocks may become quite woody. They are commonly used for propagation. Cuttings from them readily form numerous adventitious roots. Hop plants send out, near the ground line, "runners" which extend several feet. These are cut into pieces, possessing two or more buds, and used for propaga- tion. They are known in hop culture as "roots." However, they are stems and not true roots. The aerial stems, commonly known as "bines," die back to the ground in the fall. The lower portion of each stalk ("bine"), below ground, does not die, but forms an addition to the root- stock. The above ground stems are herbaceous, hollow and angu- lar, and vary in color from pale green to purplish red or green streaked with purple. They have a twining habit, always winding about the support clockwise (Fig. 102) . The angle of the support de- termines, to a degree, the manner and rate of growth. The most rapid and uniform growth is made, and the longest internodes produced, when the sup- ports are vertical. The "bines" are assisted in their climb- ing and clinging to supports by the presence of hooked, re- FlG. 102. — Dextrorse twining of hop stem. 26o BOTANY OF CROP PLANTS trorse hairs on each of the six edges of the stems, and on the petioles and leaf veins. The main stems bear opposite lateral branches. These reach their greatest length near the middle of the main stem. They bear the pistillate inflores- cences (hops), and hence it is important that they be formed in abundance. Leaves. — The hop leaves are opposite, broad, palmately veined, and three- to five-toothed (Fig. 103). In palmately veined leaves there are several main veins which radiate from the leaf base. The stipules are broad, those of opposite leaves being united. Inflorescences. — Hops are commonly dioecious, rarely monoecious. Hermaphroditism in hops has been noted. Some have held that injury is the cause of this abnormality. This theory has been refuted by Stockbefger as a result of a number of experiments in which the plants were cut back, or pruned, or the tap root removed or portions of the crown removed. All of them failed to develop the abnormality (hermaphroditism). Hop plants of this type arise independ- ently of injury. They transmit the abnormality to their progeny when propagated vegetatively. It is held that perfect flowers appear only in pistillate inflorescences. Staminate inflorescences (Fig. 103, B) are paniculate, and grow from the axils of the main shoot or from the axils of lateral ones. Pistillate inflorescences (Fig. 103, A) are spike- like in appearance. They are the "hops" of commerce and are often spoken of as "burrs" or "strobiles." These are mostly borne on lateral branches from the main stem; they arise in the axils of the leaves. The pistillate inflorescence has a central, hairy axis (Fig. 103, C) upon which are arranged a number of very short lateral branches or axes. At the base of each short lateral branch, or axis, is a pair of bract-like structures. These are in MORACEiE .61 I Pj(- 103 —Hop (Huniulus lupulus). A. portion of plant showing pistillate inflorescences; B, staminate inflorescence; C, rachis of pistillate inflorescence ("hop"). 262 BOTANY OF CROP PLANTS reality stipules belonging to leaves which, normally, do not develop. Each of the lateral branches bears four pis- tillate flowers. Below each flower is a single bracteole (small bract). Hence, examination of a single lateral axis or branch shows it to be made up of the following parts, from below upwards: (i) two bract-like stipules; (2) brac- 3\i^mas -brac\-hhe Jorac\eo\e -uvar\j' -perianth Fig. 104. — Hop (Humulus lupulus). A, single staminate flower; B, two pistillate flowers with bracteoles and bract-like stipule. {B after Wossidlo.) teole and first flower; (3) bracteole and second flower; (4) bracteole and third flower; (5) bracteole and fourth flower. Flowers. — The staminate flowers (Fig. 104, A) measure about 6 millimeters in diameter. They have a five-parted calyx, no corolla, and five stamens opposite the calyx lobes. Each pistillate flower (Fig. 104, B) is subtended by a single bracteole (Fig. 105, A) that partially encloses it at maturity. It has a single ovary surrounded by a cup-shaped perianth. There is one style with two long stigmas, which are covered their full length with papillae. MORACE^ 263 Pollination, Fertilization, and Development of the "Hops." — The long, brush-like stigmas adapt the plant to wind pollination. When the pistillate inflorescences are young, the stigmas protrude from between the small "bracts" and become very conspicuous. Only the basal bracts of the inflorescence are to be seen. As soon as fertilization has taken place the stigmas ("brush") drop off and the "bracts" rapidly increase in size. The necessity for fertilization to secure the best develop- ment of the "hop" has been determined by a number of observers. The hops will only develop properly when a certain number of bracteoles bear seeds. If the young pistillate inflorescences ("burrs") are enclosed in paper bags to prevent fertilization, no seeds result, and the hops are poorly developed. It is true that the bracteoles develop to some extent without fertilization of the ovules, but the bracteoles connected with normal seeds are much larger and a brighter yellow than those bearing rudimentary seeds. Furthermore, hops, not fertilized, remain in blossom longer than those fertilized. Howard has shown that hops arti- ficially polhnated start to grow out at once, while those not pollinated at all begin their growth seven to ten days later. He shows that fertilization stimulates growth, hastens ripening, improves the color and increases the mold-resisting power of the plant. Salmon and Amos have shown that, in England at least, seeded hops bearing an average of 9.5 seeds per hop, contained 15 per cent, resin and produced 147 pounds of resin per acre, while seedless hops contained 17.2 per cent, of resin and produced 92 pounds of resin per acre. It is true that there are certain disadvantages connected with growing seeded hops. Extra space is needed for growing staminate plants, and there is also a possi- 264 BOTANY OF CROP PLANTS bracteole penar 0. r^landi bility that the soil is more quickly exhausted by seeded hops than by seedless ones. The Mature Fruit.^ — The fruit (Fig. 105) is a small achene surrounded by the persistent cup-shaped perianth. The single seed within has a curved embryo about which is a small amount of endosperm. Lupulin Glands. — In the ma- ture hop, the outer surface of the bracteoles, the perianth, 'oeriont'i'i and, to a less extent, the bases of the bract-like stipules are covered with yellow pollen-like grains, the so-called "hop-meal" or "lupuhn" (Fig. 105). Each yellow grain is a cup- shaped, multicellular, glandular hair filled with a resinous secre- tion. It is an outgrowth of an epidermal cell and consists of a short stalk and a cup of one Fig. 105.— Hop (Humuius lupu- layer of cells. Each cell has a lus). A, bracteole; B, immature .1 .i.- i /• 1 r^^^ lupulin gland; C, same in section; rather thlck CUtlclc. The SecrC- D, mature lupulin gland; E, same tion of the Cells Collects jUSt in section. {B~E after Percival.) . . beneath the cuticle, raising the latter up until finally the cup-shaped depression is filled with the secretion which remains covered by the cuticle itself. In immature hops, the lupulin glands are bright yellow and transparent. In mature hops, they are a paler yellow and somewhat opaque. The commercial value of hops depends entirely upon the amount and quahty of the "hop-meal." It constitutes from 15 to 32 per cent, by weight of the hop. Geographical. — The hop grows wild in England, the MORACE^ 265 northern part of the continent of Europe and in Asia as far as eastern Siberia and south to Persia; it also grows wild in North America, across the continent westward to New Mexico and British America. It requires a moist, cool cli- mate to attain its best development. Oregon, California, New York, and Washington are the leading States in the commercial production of hops. Closely Related Species. — Humulus japonicus, the Japa- nese hop, is grown as an ornamental plant. It is an annual; its pistillate inflorescence does not enlarge into a "hop." Along streams from Wyoming to Utah, New Mexico and Arizona, there is a hop {Humulus lupulus neomexicanus) which is distinguished from the Linnaean species by its more deeply divided leaves and more sharply acuminate bracts. Varieties. — There are a number of varieties of hops, based upon length and color of vines, size, shape and color of hop, shape of bracteoles and stipular bracts, aroma, lupulin con- tent and time of ripening. In CaHfornia the chief variety is Large Gray American. Common New York varieties are English Cluster, Pompey, Humphrey Seedling and Canada. Composition. — The composition of the strobiles or hops is of great importance, for they possess the valuable constitu- ents of the plant, most of which reside in the lupulin glands. There are four principal active ingredients in the "lupulin," as follows : 1. Essential oil. 2. Non-resinous bitter principle. 3. Resins. 4. Tannin. Hop oil is volatile and gives the hop its characteristic aroma. The amount of essential oil in hops varies from 0.2 to 0.8 per cent. The non-resinous bitter principle of the hop 266 BOTANY OF CROP PLANTS hop is probably the alkaloid, lupuline. Of the resins in the lupulin glands, two principal ones have been identified, a hard and a soft resin. The hard resin has a slight bitter taste and little or no antiseptic power in the beer wort. The soft resins are much more bitter, imparting this taste to the beer wort; they also prevent the growth of bacteria in the wort and thus have a preservative effect. The total resin content of hops varies from lo to i8 per cent. Hop tannin makes up about 4 to 5 per cent, of the hop. It is thought by some that it serves to precipitate the albuminous material from beer wort. Uses of Hops. — In some European localities, young hop sprouts are used as an early spring vegetable. The most tender sprouts are those which have been covered with soil during the winter. Before the days of yeast cakes, yeast for bread-making was made by cultivating wild yeast in a decoction of hops and water. Some of the material obtained was mixed with the dough. The various constituents extracted from the hops add flavor to the bread, and also have antiseptic properties. The most important use of hops, however, is in the brewing process. Preparatory to their use in the breweries, the hops are taken through a curing process in which they are kiln- dried, and then subjected to the fumes of burning sulphur. "Sulphuring" bleaches the hops, and acts as a preservative. After the sweet beer wort is made in the brewing process, it is boiled with hops. In this process, among other effects, the flavor of the wort is improved by the extraction of the active ingredients in the hops. The essential oil of the lupu- lin glands imparts an aroma to the beer, the non-resinous bitter principle and the resins give to the hopped wort a slightly bitter taste, and the tannin probably serves to precipitate albuminous substances. Moreover, the malic and citric MORACE.E 267 acids in the hops tend to increase the acidity of the wort, and the ash adds to its mineral composition. FICUS (Fig) Habit, Roots, Stems.^ — Members of this genus are trees, shrubs or woody cHmbers (hanas). A number of species are parasitic on other trees. A parasite is an organism which secures its food material from another living organism. A complete parasite has no power of making its own food as do those plants which possess chlorophyll. The Golden Fig {Ficus aurea) begins life as an epiphyte; the seed germinates in the crevices of other trees; the aerial roots that are first produced take root when they strike the soil, and hence be- come trunk-like. Aerial roots may be sent down from branches, take root and also form trunks. The banyan tree {Ficus henghalensis) also starts its life on the bough of a tree, receiving all its nutriment from substances available on the bark. Hence in its early life the banyan is an epiphyte. When once rooted in the soil, the plant becomes independent. In the East Indies, the banyan is "universally known as an immense living columned hall, consisting of a flat expanded canopy of leaves and numerous stem-like prop roots growing down from the boughs" (Schimper's Plant Geography). Leaves. — The leaves are alternate, sometimes opposite, thick, leathery and deciduous or persistent. In the Buddhists' sacred Peepul tree {Ficus religiosa), a plant of tropical rain forests, the leaves have a long "dripping point," by means of which rain water is soon drained off. The stipules are interpetiolar and early deciduous. Inflorescence. — The flowers occur within an enlarged, fleshy, hollow receptacle (Fig. 106) which is commonly borne in the axils of leaves. Staminate and pistillate flowers may be borne in the same receptacle or in different receptacles. 268 EOTANY OF CROP PLANTS Some tropical figs are cauliflorus, that is, the receptacle with its numerous small flowers is borne on main stems or branches. This is a rather unusual condition ; in our common woody plants, the flowers and fruit are borne on young twigs only. S laminate flowers have a two- to six-parted perianth (some- times none), and one to three stamens with united filaments. In the staminate flowers, there is no indication of an ovary. Fig. io6. — Pollination of the fig (Ficus carica). A, medium lengthwise section of a synconium containing fertile pistillate flowers; note the female fig wasp near the orifice, also another one which is inside. B, similar section of synconium showing gall flowers. {After Kerner.) Pistillate flowers have a two- to six-parted perianth (some- times none), a single one-celled ovajy and single style. The small nutlets are enclosed in the thick, succulent receptacle, forming a fruit known as a synconium ("fig"). Geographical Distribution, and Economic Importance.^ — There are about 600 species of the genus Ficus very widely distributed throughout the American tropics, southern Asia and the islands of the Pacific. Two species, F. a urea and F. brevifolia, are native to peninsular Florida and the Keys, while F. carica has been introduced into southern California MORACE^E 269 and a number of the Gulf States. As compared with other genera in the family Moracea), Ficus is by far of the greatest economic importance. The most important species is Ficus carica, the common fig of commerce. FICUS CARICA (Common Fig) Habit of Plant, and Stem.— The common fig is a shrub or small tree, seldom reaching a height of more than 25 feet. The main trunk of the tree is short. It branches rather irregularly, forming a round head. The gray or reddish bark is smooth and fits closely to the wood. The twigs are stout and thick, at first somewhat hairy but later becoming smooth and grayish-green in color. The fig is propagated mainly from stem cuttings. Leaves. — These are thick and leathery and from 5 to 15 centimeters long. The general outline of the leaf is usually oval, sometimes about circular. The leaf base is truncate or shghtly heart-shaped. There are five to seven deep lobes, which are coarsely toothed or slightly lobed again; each lobe is blunt at the tip. The leaves are light green, rough and hairy on the upper side, paler and hairy on the under side; leaf venation is prominent. Inflorescence, and Flowers. — The numerous small flowers line the inner wall of a hollow receptacle (Fig. 106), except near the small opening ("eye") at the apex where there are scales or small leaves. Among the various types of Ficus carica, there are four distinct kinds of flowers, staminate, pistillate, gall and mule. Staminate Flowers (Fig. 107, E).- — These rarely occur in cultivated figs, being found for the most part in the wild fig (Caprifig). They occur just below the scales in the receptacle. Each staminate flower usually has a four-lobed 270 BOTANY OF CROP PLANTS perianth which is shorter than the stamens. The stamens vary from one to live; four is the ordinary number. Fig. 107. — Flowers of fig (Ficus carica). A, B and C, mule flowers; D, long-styled pistillate flower; E, staminate flower; F, gall produced from a short-styled gall flower; G, fig wasp escaping from a gall; H, gall flower. {A, B, and C after Eisen; D to G after Kerner; H after Solms-Lauhach.) Pistillate Flowers {Fig. 107, D). — Pistillate flowers are some- times found in the Common Mission figs; they are the only sort in Smyrna figs; they also occur in the second crop of San MORACE^ 271 Pedro figs, the first crop of Adriatic figs, the second crop of Erinocyce figs and the second crop (mammoni) of Caprifigs. In the receptacle of the latter, they come below the staminate flowers. The pistillate flowers have a three- to five-lobed perianth, which is rather fleshy. The single, superior ovary bears a bent style several times longer than the ovary, and often divided into two unequal stigmatic lobes. Gall Flowers (Fig. 107, H). — These are found only in Capri- figs and Erinocyce figs. They are degenerate or transformed pistillate flowers, not producing seed; the ovary harbors the eggs and larvae of the fig wasp (Blastophaga). It must not be thought that gall flowers are true pistillate flowers modified by the fig wasp; they exist independent of the wasp; the wasps select them for the deposit of their eggs. Gall flowers occur at the base of the receptacle. Their perianth is smaller than that in true pistillate flowers; the style is very short or entirely wanting; the embryo is imperfect and the stigmas do not possess receptive papillae. Mule Flowers (Fig. 107, A, B, C, ). — With the exception of an occasional pistillate flower, mule flowers are the only kind found in the common edible fig. They are also the only sort present in the first crop of San Pedro figs, and second crop of Adriatic figs. They are not present in Caprifigs. They are imperfect pistillate flowers neither capable of matur- ing seed nor serving as a breeding place for the fig wasp. The style is intermediate in length between that of gall and of true pistillate flowers; the stigmas are non-receptive; the embryo is imperfect, and hence no seed is produced. Pollination. — The common edible fig comes to maturity without polHnation, artificial or otherwise. In other types of figs all or at least one of the crops require the visitation of the fig wasp {Blastophaga grossorum) in order that the fruit form properly. The close dependence of certain figs upon this 272 BOTANY OF CROP PLANTS insect has been a topic of great interest to students of botany. Pollination in the Caprifig will be considered first. Crops of Fruit in Caprifigs. — In the wild fig (Caprifig) there are three crops of fruit in a year. These are as follows: First Crop (Profichi). — The figs of this crop form in the autumn, rest over the winter and mature the following June or July. They bear staminate and gall flowers but no pistillate flowers. When the figs are about one-fourth grown, female wasps enter and deposit their eggs in the gall flowers. In about two months, the eggs hatch out, the perfect wasps emerge and the females, covered with pollen, come from the fig and seek other figs in which to deposit their eggs. By this time (June and July) the second crop of figs is about one-fourth grown. Second Crop (Mammoni). — The fruits of this crop possess staminate, pistillate and gall flowers. The wasps which emerge from the figs of the first crop enter the narrow orifice at the apex of the receptacle (second crop), crawl down along the inner side, first over the staminate flowers, then over the pistillate flowers, finally reaching the gall flowers at the base of the receptacle, in which they deposit the eggs. The pollen on their bodies is rubbed off on the receptive stigmas, which are elevated on the long, curved styles, and thus polli- nation is secured. As a result, a few fully developed seeds are found in the second crop of Caprifigs. In August or Sep- tember the eggs, deposited in the gall flowers of the second crop, hatch out. The mature female wasps emerge from the receptacle, in search of other figs in which to lay their eggs. By this time the third crop of Caprifigs is about one- fourth grown. Third Crop (Mamme). — The figs of this crop possess staminate and gall, but no female flowers. When they are about one-fourth grown, in August or September, MORACEiE 273 wasps from the second crop come to them, depositing eggs in the gall flowers. 'I'hese tigs, together with the eggs of the wasp, hibernate until March or Aj)ril, when the per- fect insects hatch out, seeking the profichi stage. Caprification. — It will be recalled that the com- mon edible fig matures its fruit without fertilization. Such is not the case with some other types, particularly Smyrna figs. The latter have only pistillate flowers and, unless these are fertilized, the receptacle does not dome to full maturity. Hence, it has been found necessary, in order to grow Smyrna figs, to resort to artificial fertilization. The artificial process of fertilization as applied to figs is termed caprification. In this horticultural process, a number of first-crop figs (profichi) of the Caprifig are sus- pended on the branches of the Smyrna tree. The female Blastophagas which hatch from the eggs in the gall flowers of the profichi become covered with pollen as they emerge from the figs. In search of a place to lay their eggs, they go to the partly mature figs of Smyrna. They enter the orifice of the fig and scatter pollen on the stigmas, and fer- tilization of the ovules ensues. The pistillate flowers of the Smyrna fig, unlike the gall flowers, have styles of such a length that the wasps are unable to lay their eggs in the proper place. Consequently, the wasps perish in the fruit and their bodies are absorbed by the growing cells. Gall flowers are the only ones in which eggs may be laid prop- erly, and hatch. In California, caprification of Smyrna figs is done in June or July. The second crop of San Pedro figs and the first crop, but not the second, of Adriatic figs, require caprification. Effects of Fertilization {caprification). In caprifigs, as has been noted, there are two general types of receptacles: those IS 274 BOTANY OF CROP PLANTS possessing pistillate flowers (mammoni) and those without pistillate flowers (profichi and mamme). The effects of fertilization rriay be observed in comparing the behavior of caprificated figs of the mammoni with the non-caprificated ones of the profichi and mamme, or the non-caprificated ones of the mammoni. Prior to fertilization, the figs of the two types are about the same size. Caprificated figs become larger than those not fertihzed; they cling to the tree more tightly, the ribs are more pronounced and the branches that bear them grow more vigorously. As has been indicated, Smyrna figs must be caprificated to bring about the development of the ovaries ai\d seeds and the proper ripening of the receptacle. The superiority of Smyrna figs is due to the aromatic flavor of the seeds. The Mature Fruit— The "fruit" of fig (Fig. io6) is termed a synconium. This is a pear-shaped receptacle on a very short stalk; the nutlets (true fruits), when present, are im- bedded on the inside of the fleshy receptacle walls. At the apex of the fig, is the "eye" or orifice of the receptacle. The "neck" and "cheeks" (sides) of the fruit are marked by a number of rings. The fruits vary widely as to size, form, neck, stalk, ribs, eye, color of skin, color of pulp, seeds, quality and growth. Geographical. — Ficus carica is considered to be a native of southern Arabia. Some one or more of its different types are now grown in most of the tropical and subtropical coun- tries. The first figs brought into the United States were a common edible type and were introduced into California by the Franciscan order of Mission Fathers. From California, they have spread and are now being cultivated in many of the Southern States. Fig culture in the cooler sections of the United States is very limited, and special care needs to be HORACES 275 taken there to prevent the trees from winter-killing; this object is attained by growing the plant in a bush form and covering it with several inches of soil during the winter. Closely Related Species in the United States. In Florida, there are two native figs {F. aurea and F. hrevifolia) which are distinguished from the common figs by their entire, smooth leaves, and small, inedible fruit. Types of Figs. — Eisen describes the following types of figs : 1. Common Figs or Mission Figs. — These produce two crops of fruit without caprification or fertilization. Mule and a few pistillate flowers are present, but there are no gall or staminate flowers, except in a very few cases. The figs of the first crop occur on old wood. First crop figs are called "Brebas." Second-crop fruit is borne in the axils of current leaf growth, on new wood. Second-crop figs are called "Summer figs." Brebas are large figs, not very rich in sugar, and are desirable for eating fresh. Summer figs are smaller and 'sweeter, and hence are suitable for drying. 2. Smyrna Figs (known in California as "Bulletin Smyrnas" or "Lobfigs"). — These bear only pistillate flowers and produce fruit only when caprificated or hand-pollinated. The seeds produced are perfect, and it is the aromatic quali- ties in them to which the superiority of Smyrna figs is due. Smyrna figs are now grown with success in California. 3. San Pedro Figs. — These produce but one crop, the Brebas. The second crop possesses only pistillate flowers, and the fruit drops before reaching maturity. First-crop figs bear mule flowers only. 4. Adriatic Figs. — This is a type of figs in which the Brebas require caprification, while the second crop does not. 5. Erinocyce Figs. — This is a rare type in which the first crop is inedible, producing staminate and gall flowers, while the second crop has both pistillate and gall flowers. 276 BOTANY OF CROP PLANTS 6. Cordelia Figs. — These are also rare. They are an edible fig possessing only staminate flowers. 7. Caprifigs. — This is considered to be the original type of fig from which all the above have come. They grow wild in southern Europe, northern Africa and western Asia. There are three crops of Caprifigs: First crop {profichi), which bear staminate and gall flowers, but not pistillate. The receptacles form in the autumn, maturing the following June or July. Second crop (mammoni) ; staminate, pistillate and gall flowers occur in the figs of this crop. The fruit matures in August or September. Third crop (mamme) ; the figs of this crop have only staminate and gall flowers. They hibernate over the winter, reaching maturity in March or April. Uses of Figs. — Figs are grown chiefly for the fruit. This is sometimes eaten fresh, but is more commonly dried for transportation. Brebas are juicier than Summer figs, and hence are more desirable for eating raw. Summer figs and Smyrnas, however, are richer in sugar, and for this reason are better for drying. A limited area of land near Smyrna produces the largest percentage of dried figs. How- ever, the industry of drying figs is growing in California. Here, the figs are washed in salt water, dried, and rewashed in salt water, graded, and packed. Fig syrup is a medicinal product of the fruit. The fig tree is sometimes planted for ornament and shade, and the soft, light, but elastic wood finds considerable use. CANNABIS SATIVA (Hemp) Description. — The common hemp is a stout, erect, branch- ing annual, 5 to 15 feet high. The main stem is hollow and produces a few branches near the top. The leaves are alter- nate above and opposite below. They are compound, MO RACE iE 277 digitate, with live to eleven linear-lanceolate, pointed and serrate leaflets. Hemp is dioecious. The stamina te in- florescences (Fig. 108, A) are in axillary, narrow and loose panicles, the pistillate in erect, leafy spikes, also axillary. The staminate flower is borne on a slender pedicel subtended by a bracteole; it has five dis- tinct sepals and five short stamens. Each pistillate flower (Fig. 108, B) is sub- tended by a leafy bract, and possesses a single, thin, entire calyx segment, wrapped about the ovary. The ovary has two thread- like feathery stigmas. Hemp is wind-pollinated. The ovary matures into an ovoid, hard achene. The curved embryo is imbedded in a fleshy endo- sperm. The fruits of hemp are much larger and heavier when grown in a moist habitat than when grown in a dry one. Geographical. — The nuti\'e home of common hemp is central and western Asia. It has spread, as a result of cultivation, throughout Europe, Asia and An\prira. In many places, it has escaped from cultivation and become a rather troublesome weed. Fig. 108. — Hemp (Cannabis sativa). A, branch of staminate plant; B, single pistillate flower. {B after Wossidlo.) 278 BOTANY OF CROP PLANTS Varieties, — Nearly all hemp grown in this country is of Chinese origin. The Japanese hemp is identical, or very similar, to Chinese hemp. European varieties (Piedmont, Neapolitan, Hungarian, and Russian), often termed Smyrna types, differ from the Chinese and Japanese ones in that the plants are shorter, the growth is more compact, the seeds are in denser clusters and earlier in maturing. The best quality of hemp fiber comes from Italy. Ky. Agricultural Eiptriment Station Fig. 109. — Cutting hemp, Kentucky. {From Essentials of Geography, Second Book. Copyright, 1916, by Albert Perry Brigham and Charles T. McFarlane. American Book Company, Publishers.) The Hemp Industry in the United States. — Since about the year 1906, there has been a slight decline in the domestic production of hemp. This falling off has been due to the difficulty of obtaining laborers to do the work of retting, breaking, and preparing the fiber for the market; to the lack of development of labor-saving machinery; to the fact that greater profits are derived from raising other crops in hemp- HORACES 279 growing regions; and to the greater use of other libers in the manufacture of products formerly made of hemp. Kentucky began to raise hemp in 1775, and that State now leads in hemp production. Kentucky now furnishes the seed for nearly all of the hemp grown for fiber in the United States; the hemp from this State is mostly of Chinese origin. The chief hemp-growing States are Kentucky, Cali- fornia, Nebraska, Indiana, New York, and Wisconsin. Preparation of Hemp for Market. — Harvesting Hemp.— In some places, hemp is still harvested by hand with a reaping knife or hemp hook. However, in most hemp-growing dis- tricts, sweep-rake reapers, mowing machines, or self-rake reapers are used. The hemp stalks, usually 8 to 14 feet long, are bound into bundles about 10 inches in diameter, and shocked. They are allowed to stand in the shocks for ten to fifteen days, or until they are dry enough to be stacked. There is an advantage in stacking hemp, in that it rets more quickly and more uniformly than hemp that is taken directly from the shock.- Furthermore, the stacking of hemp improves the quality and yield of the fiber. Retting. — This is a process in which the substances sur- rounding the bast fibers are partially dissolved, thus allowing the fibers to be separated from the wood ("hurd") and thin outer bark, and from each other. This separation is due to the decomposing action of bacteria, in fact the retting organ- ism has been isolated and grown in pure cultures. There are two commercial methods of retting: dew-retting and water- retting. The former is the common method in this country. The hemp stalks are spread out in thin, even rows on the ground, where they are exposed to alternate freezing and thawing, or to cool, moist weather. The process of retting is complete when the bark separates easily from the woody 28o BOTANY or CROP PLANTS portion ("hurd") of the stem. Water-retting is practised in European and Asiatic countries. The stalks are immersed in streams, ponds, or artificial tanks. Breaking. — In the breaking process, the inner cylinder of wood is broken in pieces, which permits it to be removed, leaving behind the long bast or hemp fibers. The removal of the broken pieces of woody tissue is known as scutching. In this country, both hand breaks and machine breaks are in use. The stems must be dry before breaking, so as not to injure the fibers. Hackling. — The long, straight hemp, known as rough hemp, is sorted and hackled by hand. In the process of hackling, the rough fiber is combed out by drawing it over coarse hackles; the product is known as "single-dressed hemp.'" This may be combed out by drawing it over finer hackles, thus preparing a fiber known as "double-dressed hemp." Double-dressed hemp brings the better price on the market. Hemp tow is from broken or tangled stalks, and is inferior in quality to the long, straight hemp. Uses of Hemp. — Hemp is grown primarily for its fiber. The fibers are in the bast and average about 20 milHmeters in length. They are of the best quahty if the plants are cut when staminate plants are in full bloom. If cut too early, the fibers lack strength, and if harvested too late they are coarse and brittle. Hemp fiber is put to a variety of uses. It is used in the manufacture of sail cloth, yacht cordage, binder twine, tying twine, carpet yarns, carpet thread, sacking, bagging, rope, upholstery webbing, and belt webbing. The ravelings of hemp rope, termed "oakum," are used for calking seams of wooden boats and joints of iron pipe, in pumps, engines, and other machinery. The seed of hemp is often fed to poultry and cage-birds. Moreover, the seed contains 20 to &^ HORACES 281 25 per cent, of an oil, which is sometimes extracted and used as a substitute for linseed oil. The drug Cannabis indica is derived from the stems and leaves of common hemp, which under the hot climatic conditions of India, chiefly, develop a volatile oil and a strong narcotic resin (cannabin). These substances are secreted by the glandular hairs on stems and leaves. They are not produced to any extent in cold climates. Hemp-seed oil is used for making soft soaps, as a paint oil, and low grades are utilized for certain varnishes. Recent tests show that a fair quality of paper can be made from hemp "hurds." The chief fiber competing with hemp is jute. Jute is produced in India from two species of plants, Corchorus capsular is and Corchorus olitorius. It is used extensively for the manufacture of sugar sacks, gunny sacks, burlaps, grain sacks, and wool sacking. It is about two-thirds as strong as hemp fiber of the same weight, and is not as durable. Although hemp has been used to some extent in the manu- facture of binder twine, most of the binder twine now is made from the fibers of sisal and abaca. Sisal Hemp. — The main center of production for Agave fibers is Yucatan in Mexico. On the low limestone plains of this country, Agava sisalana thrives. It belongs to a differ- ent family (Amaryllidaceai) than that to which common hemp belongs. This plant yields the well-known "sisal hemp" or "hennequin." The plant is cultivated. This country now imports large quantities of sisal hemp, all of which is from Yucatan. It is used mainly in the manufac- ture of binder twine. About 200,006,000 pounds of binder twine are required annually to harvest the grain, corn, and flax crops of the United States. Practically all of the fiber from which this twine is made comes from the Agave plant of Yucatan. 262 BOTANY OF CROP PLANTS References Bailey, L. H.: Mulberries. Cornell Agr. Exp. Sta. Bull. 41: 223-243, 1892. Sketch of the Evolution of Our Native Fruits. The Macmillan Co., 1898. Briant, Lawrence, and Meacham, C. S.: Hops. The Influence of Climate, Ripeness, Soil, Drying, and General Manipulation on the Value of Hops. Jour. Fed. Ins. Brewing, 2: 423, 1896. Chapman, A. C: The Essential Oil of Hops. Proc. Chem. Soc. (London), 9: 177, 1893; lo- 227-229, 1894. Jour. Chem. Soc. (London) Trans., 67: 54-63, 1895a. Jour. Fed. Inst. Brewing, 4: 224-233, 1898. Jour. Chem. Soc. (London) Trans., 83: 505-513, 1903. The Hop and its Constituents. A Monograph on the Hop Plant. London, 1905. Published by Brewing Trade Review. Chedsey, M.: The Influence of Pollination upon the Development of the Hop {Humidus lupulus). Plant World, 8: 281-283, iQOS- Cook, O. F.: Sexual Inequality in Hemp. Jour. Hered., 5: 203-206, 1914. Eisen, Gustav: Edible Figs, their Culture and Curing. U. S. Dept. Agr. Div. Pom. Bull. 5: 1-33, 1897. The Fig: Its History, Culture, and Curing. U. S. Dept. Agr. Div. Pom. Bull. 9: 1-317, 1901. Biological Studies on Figs, Caprifigs, and Capritication. Proc. Cal. Acad. Sci., ser. 2, vol. 5: 897-1003, 1896. Gross, E.: Hops in Their Botanical, Agricultural, and Technical Aspects and as an Article of Commerce. Scott, Greenwood & Co., London, 1900. Transl. from German by C. Salter. Howard, A.: Hop Experiments in 1904. Councils Kent and Surrey. South- eastern Agr. Col., Wye, Bull, i: 1-29, 1904-5. The Influence of Pollination on the Development of the Hop. Jour. Agr. Sci., i: 49-58, 1905. Howard, L. O. : The Present Status of the Caprifig Experiments in California. U. S. Dept. Agr. Div. Ent. Bull. 20 (new ser.): 28-35, 1899. Smyrna Fig Culture in the United States. U. S. Dept. Agr. Yearb., 1900: 76-106, 1901. Matthews, J. M.: The Textile Fibers: Their Physical, Microscopical, and Chemical Properties. John Wiley & Sons, 191 1. Myrick, H.: The Hop: Its Culture and Curing, Marketing, Manufacture. Orange Judd Co., 1899. Power, F. B., Tutin, F., and Rogerson, H.: The Constituents of Hops. Jour. Chem. Soc. (London), 103: 1267-1292, 1913. Rabak, F.: Aroma of Hops: A Study of the Volatile Oil with Relation to the Geographical Sources of the Hops. U. S. Dept. Agr. Jour. Agr. Research, 2: 115-159, 1914- HORACES 283 Salmon, E. S., and Amos, A. : On the Value of the Male Hop. Jour. Southeast. Agr. Col., Wye, 17: 365-391. iQoS. S.'VLMON, E. S.: The Pollination and Fertilization of Hops and the Characteris- tics' of "Seeded" and "Seedless" Hops. Jour. Agr., 21: 22-31, 123-133, 1914- ■ . . f The Pollination and Fertilization of Hops and the Characteristics of "Seeded" and "Seedless" Hops. Jour. Bd. Agr. (London), 2: 123- 133; 3: 23-220; 20: 953-966; 21: 22-31, 1914- Schmidt, J.: Investigations on Hops, V. On the Aroma of Hops. Compt. Rend. Lab. Carlsberg, 11: 149-163, 1915- Stockberger, W. W.: Change of Sex in Humulus Lupulus not Due to Trau- matism. Abs. in Sci., n.s. 31: 632, 1910. TouRNOis, J.: Sexual Studies of the Hop Plant. Ann. Aci. Nat. Bot., g ser., 19: 49-191, 1914 . T. ' ■ u ,1 1 WiNGE, O.: The Pollination and Fertilization Processes in Humulus Lupulus L. ' and H. Japonicus Sicb. et Zucc. Comp. Rend. Lab. Carlsberg, 11: 1-46, 1914- CHAPTER XXII POLYGONACE^ (Buckwheat Family) Herbaceous representatives of this family are largely found in temperate regions, tree- like species in American tropics, while shrubby ones are limited to western Asia. There are about 30 genera and 800 species. Rhubarb and buckwheat are the prin- cipal cultivated members, while a number of species of Rumex (dock) , and of Polygo- num (knotweed, bind-weed, etc.) are bad weeds. Stems. — T he stems are conspicuously jointed and usually swollen at the joints. The leaves are alternate (Fagopyrum), opposite {Ma- counastrum) , or whorled (mountain sorrel, Oxyria digyna). They are mostly entire, rarely lobed or divided. The stipules, with a few ex- FiG. no. — Leaf of common buckwheat . , (Fagopyrum vuigare) . X i . c c p 1 1 o n s , are mcmbrauous, sheathing, and united to form a very characteristic structure, the ocrea (plu. ocrete) (Fig. no). 284 k POLYGONACE^ 285 Inflorescences.-^Thc injloresccnces vary a ^reat deal within the family; in buckwheat they are panicled racemes, in Polygonum spj)., terminal or axillary spike-like racemes, in Eriogonum spp., cymes, umbels or heads. The cyme is a determinate type of inflorescence. In this type, the terminal flower is the oldest and subsequent ones open in order from the inside to the outside of the inflorescence (centrifugal open- ing of the inflorescence). In the head type of inflorescence, so well exemplified by the dandelion or sunflower, the flowers are crowded on the receptacle; the stalk of each flower is very short or entirely absent; it is an indeterminate type. Flowers. — The flowers are small, mostly perfect, rarely dioecious or monoecious, and radially symmetrical. In the genus Eriogonum, the flowers are subtended by a five- to eight-toothed involucre. The calyx consists of two to six segments which are below^ the ovary and free from it; the segments are in one or two series, often imbricated (over- lapping), and the inner or both series are petaloid (resembling petals). There are no petals. The stamens vary from two to nine; in perfect flowers, they are attached near the base of the calyx, while in staminate ones, they may be crowded on a central disk; the filaments are fihform, mostly distinct but sometimes united in a ring at the base, and commonly dilated at the base; the anthers possess two cells, and are longitudinally dehiscent. The pistil is solitary. The su- perior ovary is one-celled, three-angled or compressed, rarely four-angled, and usually sessile; the styles are most frequently three in number, rarely two or four, and attached to the apex of the ovary; the stigmas are capitate (head-shaped) or tufted, and sometimes two-cleft. Within each ovary there is a single ovule. Fruit. — The fruit is a three-angled (rarely four-angled) achene, about which is frequently the persistent calyx; the 286 BOTANY OF CROP PLANTS pericarp is hard or leathery. The single seed in each fruit assumes the shape of the pericarp; the seed coat (testa) is membranaceous, the endosperm is abundant and mealy, and the embryo is straight or curved. Key to Principal Genera Flowers subtended by involucres; ocreae wanting, Eriogonuni. Flowers not subtended by involucres; ocreae present. Calyx six-parted (rarely four). Stamens nine (very rarely six), Rheum (rhubarb). Stamens six, Rumex (dock). Calyx five-parted (rarely four). Achene much surpassing the calyx, Fagopyrum (buckwheat). Achene enclosed by the calyx, Polygonum (bistort, persicaria, knot weed, bindweed, etc.). RHEUM RHAPONTICUM (Rhubarb, Pie Plant) Roots, Stems, Leaves, Flowers.^ — This plant is a perennial from large, quite woody rhizomes which have a fibrous and Fig. III. — Rhubarb (Rheum) flower, external view, median lengthwise section, and with perianth and stamens removed. {After Liirssen.) well-developed root system. The rhizome is used in the propagation of the plant. In the spring, a number of large leaves are sent up from the underground stem, and, later in POLYGONACE^ 287 the season, there arise tlower shoots, bearing elongated leafy inflorescences, crowded with small whitish flowers. Unless seed is desired, flower shoots should be promi)tly removed, Fig. 112. — Rhubarb (Rheum rhaponticum) plant, in fruit. as they require considerable food supply which should go to the support of the roots. The leaves are large, circular in outline, cordate at the base, and with sinuate veins beneath; leaf petioles are semi-cylindrical and bear membran- 288 BOTANY OF CROP PLANTS ous ocreae. The flowers are on short, jointed pedicels and occur in fascicles, each of which is a raceme; the entire inflorescence is paniculate. The flowers (Fig. 1 1 1) are small, greenish white and perfect; the calyx is six-parted, persistent, and becomes enlarged somewhat in the fruit (Fig." 113); there are nine stamens; the ovary is three-angled and bears three short, recurved styles, with large stigmas. --^-perj latent jt\jles pemstent cal\jx lobe Fig. 113. -Fruit of rhubarb (Rheum rhaponticum). A, external view; Bi cross-section. X 5. Self-pollination is prevented to a large degree by the matu- ration of anthers before the stigmas. Stigmas of flowers below on the inflorescence receive pollen from the anthers of younger flowers borne above them. Pollen is disseminated by wind, insects, and gravity. Fruit.- — Rhubarb fruit (Fig. 113) is an achene surrounded at the base with the persistent remains of the perianth; it has three broad, thin wings which are traversed by a longitudinal nerve running near the margin; it is tipped by a small per- POLYGONACE^ 289 sistent style. The seeds are three-angled, conforming in shape to the fruit; the testa is thin and red; the hilum and micropyle are basal; the endosperm is abundant and sur- rounds the large, straight embryo. Good-sized plants can be raised from seed in one season if it is planted early. The seedlings of rhubarb show interesting variation. Geographical, and Varieties.— The common rhubarb is a native of Asia. It has become introduced into many coun- tries of the temperate climates. It is a cool season crop that will withstand summer heat, and the roots winter freezing. It is claimed that a "number of the varieties now grown are hybrids between R. rhaponticiim, R. undulatum and R. palmatum. The principal varieties grown are Linnaeus, Victoria and Monarch. There are a number or ornamental species of Rheum, most of which are distinguished from com- mon rhubarb by their more or less lobed leaves, the margins of which may be coarsely or finely toothed. Uses. — Rhubarb or pie plant is a vegetable used for its large, acid leaf stalks, which are of the best quality early in the season. The leaf stalks are usually made into pies or sauce, and occasionally wine is made from the juice. FAGOPYRUM VULGARE (Common Buckwheat) Roots. — Common buckwheat is an annual, from 2 to 4 feet tall. It has a small root system. There is a single primary root which may reach down to a distance of 3 or 4 feet; side roots are given off along the primary, but they do not extend far into the soil. Buckwheat differs from the true cereals, in the possession of a single primary root, and a much less extensive root system. Stems. — The stems are quite succulent, smooth, except at the nodes, and strongly grooved. Each seed gives rise to but one stem which may branch freely, but, unlike grasses, no 19 290 BOTANY OF CROP PLANTS ''suckers" or "tillers" are produced. The amount of branching depends upon the thickness of seeding; the plants branch freely when not crowded and feebly when crowded. The young stems vary from green to red, and turn brown with age. Fig. 114. — Buckwheat (Fagopyrum vulgare). Leaves. — The leaves are alternately arranged on the stem and characteristically hastate (halberd-shaped) (Fig. no), or triangular heart-shaped; they may be sessile or short- petioled, and bear an ocrea (Fig. no), which soon falls off. POLYGONACEvE 291 Inflorescence.— The inflorescence is a raceme which may be either paniculate or corymbose (a corymb is a flat-topped raceme type of inflorescence); it is terminal and axillary, many-flowered, and erect or slightly drooping. pericarp \ei\a -ernhnjo -nectar ^land receptacle Fig. 115. — Common buckwheat (Fagopyrum vulgare). A, achene; B, floral diagrain; C, cross-section of fruit; D, flower. (B after Wossidlo; C after Slevens.) Flowers.^ — The flowers (Fig. 115, D) are white, tinged with pink. There are no petals (hence is apetalous), but there is a five-parted corolla-like calyx which remains attached to the 292 BOTANY OF CROP PLANTS base of the fruit. There are eight stamens with glabrous hKform filaments and oblong anthers. Three of the stamens closely surround the styles and dehisce outward, while the five others are inserted outside of these three, and dehisce inward. The single ovary is one-celled and one-ovuled and bears three style branches, which are bent back in fruit. The plant begins to bloom when quite young and continues until frost. Dimorphism and Polh'nation.— Common buckwheat has dimorphous flowers, i.e., there are two forms. One of these forms has short styles and long stamens, and the other, long styles and short stamens. This condition is known as hetero- styly. The pollen grains of short-styled flowers are larger than those of long-styled flowers. Usually, all the flowers on one plant are of one form or the oti er. Occasionally, how- ever, both long-styled and short-styled plants may bear a very few flowers with styles and stamens of the same length. These "equal-styled" flowers are not fertile. The seeds from either form of flower will produce buckwheat plants, some of which produce one form and some the other. Buckwheat is regularly visited by numerous insects. Heterostyly is a condition which tends to prevent self-poUi- nation. Fruit.^ — The mature fruit (Fig. 1 15, A) is a triangular (some- times two- or four-angled) crustaceous achene, brown, streaked with black, or entirely black; the point of the "grain" is the stigmatic end, while the opposite end shows a fragment of the flower stalk (pedicel), and small, persistent, withered calyx lobes which have become adherent to the peri- carp. The "hull" is the pericarp and attached portions. Seed. — The single seed conforms in shape to the pericarp. There is an abundance of white, dry, floury endosperm in which is imbedded the embryo. Buckwheat endosperm is POLYGONACE^ 293 more starchy than that of wheat, oats, barley, rye and corn, and the fat content is lower. Consequently, buckwheat flour is low in percentage of protein and fat. The embryo ("germ "), however, has an abundance of fat and protein, and ior this reason "middhngs," which contain the embryo, are a valued stock food. In a cross-section of the fruit (Fig. 115, C), the embryo has the form of the letter S, and reaches from one of the three angles of the seed to another. -tesia - nucellus ^-aleurone T--jtarch\j endosperm Fig. 116. — Common buckwheat (Fagop\rum vulgare). seed. {After SlejieHs.) Section of mature Geographical.^ — Common buckwheat has been cultivated in China for 1,000 years. It was introduced into Europe during the middle ages. It was brought into this country by the early settlers. It has escaped from cultivation in North America, and is now common throughout northern United States and Canada. Other Species. — There are two other species of Fagopyrum, one of which, F. tataricum, at least, has been cultivated to a slight extent in this country, and is also an occasional escape from cultivation. Tatary buckwheat is distinguished from the common form by the simple racemes, its rough hull, and the w^avy fruit angles. It is cultivated where a hardy sort is 294 BOTANY OF CROP PLANTS needed. The notch-seeded buckwheat {F. emarginatum), a form cultivated in northeastern India and China, is dis- tinguished from the preceding by having the angles of the smooth hull prolonged into wide, rounded wings. Varieties.^ — Three varieties of common buckwheat are grown in the United States: Japanese, silver hull, and com- mon gray. They may be distinguished by the following key: Key to Varieties of Common Buckwheat Faces of grain slightly concave; angles extended into very short wings, Common gray. Faces of grain flat; angles not extended into wings. Grain small and plump, Silver hull. Grain large and not so plump, Japanese. Environmental Relations.^Buck wheat is a temperate- cHmate plant, finding the best conditions for growth where the summers are cool and moderately moist. Dry, hot weather is inimical to the proper setting of the fruit. Accord- ing to the work of Briggs and Shantz, buckwheat has a water requirement intermediate between that of barley and oats, the actual amount being 578. Buckwheat is known to do well on poor soils, even those in which the drainage is such as to make it impossible to grow the small cereals profitably. Uses. — The principal use of buckwheat is in the manu- facture of pancake flour. As a food for stock, it is used in various forms. The whole grain is sometimes fed to poul- try, hogs and cattle. Usually, however, the hulls are re- moved from the grain, and the seeds ground, before feeding to hogs. The middlings (hulls mixed with bran) are prized as a stock feed. Buckwheat straw is used both as a feed and a bedding for stock. Honey from buckwheat flowers has always possessed a high reputation for flavor. Buck- l£c POLYGONACE^ 295 wheat will grow well on poor soil^ — a soil that will not suj)port true cereals. Therefore, it may be used as a green-manure crop. References MoRSK, J. F.: The New Rhubarb Culture. Orange Judd Co., 1912. Stevens, N. E.: The Morphology of the Seed of Buckwheat. Bot. Gaz., 53: 59-66, 191 2. Observations on Heterostylous Plants. Bot. Gaz., 53: 277-308, .1912. TsuTSUMi, Ochimura: Studies on the Buckwheat. Bot. Mag. (Tokyo), 8: 288-291; 417-421, 1894. Williams, F. N.: Primary Characters in the Species of Rheum, 29: 292-295, CHAPTER XXIII CHENOPODIACE^ (Goosefoot FamUy) This family is widely distributed geographically. They are, for the most part, saline plants found near the ocean or in deserts and steppes. They are characteristic plants of the alkaline swamps and meadows of the western United States. Plants that are able to grow in soils very rich in salts are designated halophytes. Of course the salinity of the soil solution retards the rate of water intake by the roots, and, consequently, halophytic plants are found with structural adaptations which prevent a rapid loss of water from the leaves. Our most typical halophytic plants are found within the goosefoot family. From an economic standpoint, the family is of consider- able importance. The principal cultivated forms are the beet and spinach. A large number are weeds, chief of which are goosefoot, pigweed, lamb's quarters, strawberry blite, and Russian thistle. Habit, Stems and Leaves.^ — Members of the family are annual or perennial herbs, or shrubs {A triplex, saltbush). The stems are cylindrical or angled, erect or decumbent. The leUves are usually alternate, rarely opposite, without stipules, simple, and entire, toothed or lobed. Inflorescence and Flowers.- — The flowers may occur in panicled spikes (beet), or in globular, axillary, sessile heads [Blitum capitatum, strawberry blite) or sometimes they are solitary in the axils {Salsola, Russian thistle). The flowers 296 CHENOPODIACE^ 297 are usually small, ^; B, single achene, X 20. attachment of fruit to receptacle. The achenes are com- monly termed "seeds." Geographical. — The genus Fragaria possesses about eighteen species most of which are natives of the north temperate zone; a number are found in the Andes of South America. Strawberries are cultivated in all parts of the United States. ROSACE ^> ,:;63 Principal Fruit-bearing Species. — 'Jhe evolution of the strawberry has been given to us by Bailey. Most of our cultivated varieties of strawberries belong to the species Fragaria chiloensis. This plant is a native of western Chile, from which country it was brought to Europe at the begin- ning of the eighteenth century. The Chilean strawberry is also a native of the western coast region of North America, as well as of South America. However, some botanists would refer the forms as found in this continent to the species Fragaria californica and F. glauca. The early settlers in the Eastern States cultivated the common wild strawberry {Fragaria virginiana) which they found growing in their fields. But few cultivated varieties belong to it. Varieties of the wild strawberry of Europe {Fragaria vesca) have also been cultivated in America, but only to a slight extent. These varieties are the Everbearing or Perpetual strawberries. Hence, the varieties of strawberries in America fall into three groups, as follows: 1 . Chilean group from Fragaria chiloensis. 2. Scarlet or Virginian group from Fragaria virginiana. 3. Perpetual or European group from Fragaria vesca. These three species may be distinguished by the following key: Key to Principal Species of Fragaria Leaves usually projecting above the flowers and fruit; achenes sunken in the flesh. Runners appearing after the fruit; berry dark; calyx large; leaves shining above, bluish-white beneath, F. chiloensis (Chilean strawberry). Runners appearing with the fruit; berry scarlet; calyx medium; leaves light green on both surfaces, F. virginiana (scarlet or Virginian strawberry). Leaves usually not projecting above the flowers and fruit; achenes not sunken in the flesh, F. vesca (perpetual or European strawberry). Fragaria virginiana {Virginia or Scarlet Strawberry) . — This is a stout, dark 364 BOTANY OF CROP PLANTS green, tufted herb with soft-hairy leaves. The petioles are from 2 to 6 inches long, the leaflets oval or obovate, obtuse, dentate, the lateral not symmetrical at the base. The scape is usually shorter than the leaves, at least not exceed- ing them, hence the fruits are borne below the leaves. The calyx lobes are erect at maturit)^ The fruit is red, ovoid, and with achenes imbedded in the flesh. The species extends from New Brunswick to South Dakota, south to Florida, Louisiana and Arizona. Fragaria vesca {European Wood or Everlasting Strawberry). — This is a stout, dark green, tufted plant with hairy leaves. The leaflets are ovate or broadly oval, obtuse, dentate, the lateral not symmetrical at the base. The scape is longer than the leaves, hence the fruits are borne above the leaves. The calyx lobes are spreading or reflexed. The fruit is red, hemispheric or conic, with achenes not imbedded in the flesh. This strawberr}' is a native of Europe, but naturalized in the Eastern and Middle States. It has given us our Perpetual and Ever bearing varieties. Fragaria chiloensis {Chilean Straivberry). — The Chilean strawberry is a low form with thick leaves, shining above and bluish-white beneath; the runners appear after the fruit is gone. The fruit is large, firm, dark, with a large "hull," and with achenes sunken in the flesh. It is a native of the western coasts of South America and North America. Most of the common varieties of strawberries belong to the Chilean species. Varieties. — The number of varieties of strawberries is great. They are commonly divided into three groups as to time of maturing: first, early (Warfield, Excelsior, Bederwood); second, medium (Ridgeway, Dunlap, Marshall, Jucunda); and third, late (Aroma, Gandy, Chesapeake, Splendid). Growers distinguish between commercial varieties and those for home consumption. A good commercial variety should be hardy, very productive, of good color, firm, and of good size and form. Among good commercial varieties, may be mentioned Bederwood, Excelsior, Jucunda, Dunlap, Captian Jack, Splendid, and Parson's Beauty. Such varieties as Warfield, Ridgeway, Marshall, Aroma, and Chesapeake are grown for home use. Origin of New Varieties.^ — Strawberries seldom come true to seed; hence it is possible to secure new varieties by plant- ROSACEA. 365 ing seed. When a (lesiral)le \ariation appears, propagate it and keep it ''true'' l^y means of runners. This method of vegetative propagation insures permanency in the characters of the variety selected. Uses. — Strawberries are used chiefly in the fresh state. There is an increasing demand for such strawberry products as crushed fruit, preserves, marmalades, and jeUies. Large quantities are put up fresh for use at soda fountains and in the manufacture of ice cream. References Bailey, L. H.: Survivul of the Unlike. Essay 25, Strawberries, The MacMillan Co., 1896. Bl.\nchard, W. H.: Rubus of Eastern N. A. Bull. Torrey Bot. Club, 38: 425-439, 1911- BuNYARD, E. A.: The History and Development of the Strawberry. Jour. Hort. Soc, 39: 541-552, 1914. CoRBETT, L. C: Strawberries. U. S. Dept. Agr. Farmers' Bull. 198: 1-24, 1904. CHAPTER XXVII POMACES (Apple Family) Habit, Leaves. — Members of the apple family are either trees or shrubs. The alternate simple or compound leaves are petioled, and have small deciduous stipules. Inflorescence. — The inflorescences are racemose {Amel- anchier, service-berry), cymose (Malus, apple, Sorbus, moun- tain ash) or simple {Cotoneaster, evergreen or fire thorn). Flowers.* — The flowers (Fig. 157) are regular, perfect, and usually with a concave or cup-shaped receptacle or torus to which is attached a five-lobed or five-toothed calyx, five sepa- rate petals, numerous distinct stamens and a one- to five- celled ovary. The ovary is ordinarily five-celled, and the carpels are wholly or partly united. The carpels vary in texture from parchment-like (Malus, etc.) to bony {Cratce- gus and Cotoneaster). The number of styles varies in the different genera: generally three in Sorbus, two to five in Malus (usually five), mostly five in Pyrus (pear), two to five in Amelanchier, one to five in Cratagus (thorn apples), two to five in Cotoneaster. They may be distinct, as in Sorbus, or partly united as in Malus. The ovules are commonly two {Malus) in each cell, sometimes one {Amelanchier), or rarely several {Cydonia, quince). Fruit. — The fruit is a pome. Representatives of the family are commonly spoken of as "pomaceous. " The pome is a false or spurious fruit in which the receptacle or torus be- comes fleshy, to form the greater portion of the fruit, and encloses five bony, leathery or papery carpels (Fig. 158). 366 POMACES 367 Geographical. — The family is of wide geographical distribution, there being close to 225 species within about 20 genera. Most of the species occur in north temperate or boreal regions. Key .to Important Genera of Pomacea: Ripe carpels bony, Cralagus (thorn-apple, haw, hawthorn). Ripe carpels papery or leathery. Leaves compound, Sorbus (mountain ash). Leaves simple. Ovules one in each cavity, Amclanchicr (service-berry, June-berry). Ovules (usually) two in each cavity. Flesh of the pome with grit-cells, Pyrtis (pear). Flesh of the pome without grit-cells. Mains (apples and crab- apples). Ovules many in each carpel, Cydonia (quince). MALUS (Apples) Stems.— Malus species are either trees or shrubs. In the apple, all rapid-growing shoots develop only leaf buds. Flower buds, which in the apple are "mixed" buds, are al- most always borne on the ends of ''sptirs" or short twigs. When a "spur" terminates in a flower bud, lateral buds lower down continue the growth of the shoot, hence the crooked appearance of such spurs (Fig. 153). These lateral buds may grow for a year or so, bearing leaf buds at the terminus, and then be stopped in their growth in that direction by the formation of a terminal flower bud. As a rule, a shoot that has once started to bear flowers continues to do so, making but a very short growth of wood each year. Such a shoot is marked by the closely crowded leaf scars, terminal-bud scars, and flower and fruit scars. The position of a fruit is usually marked by a large circular scar surrounded by a number of smaller ones of the same shape. The smaller ones represent scars made by flowers or fruit that failed to develop. It has been recorded generally, particularly for Eastern orchards, that the fruit buds in apples are always terminal, and further- 368 BOTANY OF CROP PLANTS more that the fruit spur must be two or more years old before it will bear fruit. Paddock and Whii)p]e ("Fruit Growing in Fig. 153. — Spur of Yellow Transparent apple. Arid Regions") have noted that in certain districts of Colo- rado many varieties produce flower buds in the axils of leaves on the growth of the current season and that one-year-old spurs POMACE.^i 3 ^^9 may in many instances bear fruit (Fig. 154), or that fruit may be borne at the end of last year's terminal growths, not spurs. Hyslop, Mann, Missouri Pippin, Strawberry, Strii)e(l, Trans- cendent and Winesap are among those varieties producing fruit in the axils of leaves. Astra- chan, Ben Davis, Grimes, Hyslop, Jonathan, :\IcTntosh, Missouri Pippin, Newton, Northern Spy are a few varieties found to be bearing fruit on one-year-old spurs. A few varieties such as Grimes, Hyslop, Transcendent, Willow Twig, and Yellow Transparent produce fruit on the end of last year's terminal growths, not spurs. Gourley has observed axillary fruit buds throughout the Eastern States on both old and young trees, and in many varieties. Different forms of fruit branches occur; furthermore the same variety, or even tree, may bear more than one sort of fruit branch. Frequently, it has been noted that spurs bear annually, instead of biennially, as is the rule. In such a case, fruit buds are developing on a spur at the same time that an apple is maturing. It is not always an easy matter to distinguish between the fruit and leaf buds of apple. Generally, fruit buds are rather thick and rounded, while leaf buds are smaller and more .pointed. It has been shown that fruit buds are differ- entiated very early, and may be distinguished by microscopic study, from leaf buds, as early as the last week in June of the year preceding the opening of the flower. The above has been reported by Drinkard, and Kraus has observed that in the Yellow Newton apple, under Oregon 24 Fig. 154. — Mature Jona- than apples from axillary flower buds. (After Pad- dock and Whipple.) SJO BOTANY OF CROP PLANTS conditions, the fruit and leaf buds are differentiated in early July, and in early varieties, even by the latter part of May. The form of the tree, nature of twigs, branches, bark and leaves vary a great deal in the many varieties of apples. Leaves. — These are simple, alternate, and toothed or lobed; the stipules are free from the petiole. Inflorescence. — It will be recalled that the buds contain- ing flowers are mixed buds. Hence, when each opens there is developed a very short axis bearing closely crowded leaves and flowers. On this axis, the flowers are apical, the leaves basal. The flowers may be so crowded that the cyme is umbel-like in appearance. In most cases, the inflorescence is terminal, but, as has been indicated above, it is axillary in some varieties. The number of flowers in a single mixed bud may vary from two or three to eight or ten. As a rule, but one flower matures its fruit, thus illustrating the struggle for existence among the different individual flowers. The determinate inflorescence, cyme, of apple is not always definitely so. It will be remembered that in the cyme type of inflorescence the flowers open in order from the inside outward. Sometimes the central flower is tardy in its development, and often the central and some of the laterals may open simultaneously. Flowers and Their Development.— The development of the apple flower (Yellow Newton) has been worked out by Kraus. A longitudinal section (Fig. 155) of a growing axis shows a number of bracts and bud scales surrounding it; on the sides of the axis, appear the primordia of flower buds and leaves. The primordia of sepals are the first to appear. The torus develops especially toward the outer edge by a growth of the cells beneath the developing calyx, and finally takes on a concave shape. The torus continues to uprise during the development of petals and stamens, both of which POMACES 371 are seen to arise from the concave sides of the torus. Follow- ing the appearance of sepal primordia, appear petal primor- dia, then those of stamens, and lastly those of the carpels. The succession of floral cycles is acropetal, i.e., in order from without to the inside. Fig. 155. — Diagram showing the development of apple. Dotted area repre- sents pith. Not drawn to scale. {After Kraus, Oregon Agr. Exp. Sta.) The primordia of stamens appear in three cycles, those of the outer usually being laid down first (Fig. 1 56). The carpel primordia appear within the central portion of the cup-shaped torus. There are five of these surrounding a small central cavity, which is formed by a lack of growth at the center of the torus. Hence there is no common placenta, but each carpel has its two separate placentas, which in "open-cored" pomes may become closely connected. These facts will be considered again in the account of fruit development. It is thus shown by the studies of Kraus that calyx lobes, petals, stamens, and carpels are all outgrowths of the urn- shaped receptacle. 372 BOTANY OF CROP PLANTS Pollination and Fertilization.^ — The literature on this subject is extensive. Cross-poUination is the rule and self-pollination the exception in the apple and pear. Ex- periments have shown that the wind aids but little in cross- pollination, and that insects, chiefly the honey bee, are relatively more important. The bee is attracted to the flowers by the nectar which is produced rather abundantly. Fig. 156. — Floral diagram of apple (Malus sylvestris). Note that the sta- mens are in three distinct whorls. (After Kraus.) Self-sterility and Self-fertility.— Many apples and pears are self-sterile, that is, will not fertilize their own pistils. In .such cases, pollen from another variety will usually result in fertilization. Self-sterility and self-fertility probably vary with different climatic conditions. In Oregon, Lewis and Vincent found that the Spitzenburg is self-sterile but capable of being fertilized with pollen from a number of other varieties, such as Yellow Newton, Arkansas Black, Jonathan, and Baldwin. Evidently, the mutual affinities of apple varieties must be considered in setting out an orchard. It would not be well to plant solid blocks of Spitzenburg, for example. It should be alternated with rows of some one of POMACES 373 the other varieties the pollen of which is capable of fertilizing it. It is no doubt true that the failure of many varieties to set fruit is due, in part, to self-sterility. Effects of Strange Pollen.^ — The secondary effects of for- eign pollen on the mature fruit have received considerable at- tention. It is claimed by many that the pollen from one va- riety when placed on the stigma of another, immediately •5 sNiej rim of receptacle Fig. 157. — Apple (Malus sylvestris). Median longitudinal section of flower. impresses its characteristics upon the fruit. It is difficult to understand how foreign pollen could have any considerable effect of this kind. The flesh of the apple is receptacle for the most part. The sperm nuclei of the pollen, of course, do not come into contact with the nuclei of the receptacle cells. It is altogether possible, however, that uniformity of crop, percent- age of set, and size of fruit are immediately affected by strange pollen. 374 BOTANY OF CROP PLANTS Parthenocarpy.— As a general rule, lack of fertilization of the ovules in the ovary is followed by the shedding of the blossoms; the ovary fails to develop completely if a good number of its ovules are not fertihzed. However, develop- ment of the ovary does sometimes occur although fertiliza- tion fails. Such an unusual development of carpels is called parthenocarpy. This phenomenon is not unknown in the apple. With certain sorts of both apples and pears, fruits weighing loo grams have been developed without fertiHza- tion. Of course, parthenocarpic fruit is seedless. There are among cultivated plants many which bear seedless fruit. We noted that in the common Mission figs the fruit matures normally without fertilization of the ovules. Seedless to- matoes, egg plants, EngHsh forcing cucumbers, oranges, grapes, and bananas are quite common. The Fruit and Its Development. — Morphology. — There are two common opinions as to the nature of pomaceous fruits : 1. Flesh is thickened calyx tube. 2. Flesh is receptacle or torus closely connected with the carpels. The recent work of Kraus appears to establish the latter. In following through the development of the flower (Fig. 155), it is seen that the receptacle, by more rapid growth at the sides than toward the center, becomes urn-shaped and bears on the rim and inside face, calyx lobes, petals, and stamens. In the development of the fruit, there is a con- tinuation of the enlargement of the receptacle ; the throat of the receptacle becomes narrow, and through it the styles pro- trude; and the connection between receptacle and carpel tissues becomes a very close one; hence receptacle makes up the greater portion of the flesh of the apple. Ripening Process. — Important chemical changes take place POMACES 375 in the ripening process. The content of sucrose (cane sugar) increases steadily in the ripening process up to a maximum and then suddenly decreases. There is a rapid decrease of starch throughout the entire period. Invert sugar (a mix- ture of glucose and fructose) increases throughout the ripen- ing period while the total sugar increases up to the date when starch entirely disappears, after which time it fluctuates slightly. Malic acid, which gives the fruit its sourness, gradually becomes less and less. Ripening takes place in two stages. The first stage involves that portion of the fruit within the core line CFig. 158). Here there is at first a de- crease in the starch content just between the locules, at the tips of the carpels. This loss extends outward from these points to the core line. The second stage of the ripening proc- ess involves the region outside the core liRe. At first, streaks free of starch appear in the midst of this area. Soon the middle portion of the area becomes free of starch. There is a gradual increase of this starch-free area, the last regions to ripen being V-shaped areas radiating from the vascular bundles as seen in cross-section. Furthermore, anatomical changes take place in ripening. The middle lamellae of the cells soften, resulting in a slight separation of the cells, an increase in the regularity of the cell outline, in the size of intercellular spaces, and amount of intercellular air. '^Mealiness."— This results from a softening of the middle lamellae; those varieties that are comparatively very mealy have correspondingly weak lamellag. When a cell divides into two, the common primary wall between them becomes the middle lamella of the thicker wall formed by the deposi- tion of material from both protoplasts. Hence in the mature cell wall, the primary or first-formed wall appears as a defi- nite layer between the added layers. Separation of two ad- jacent cells naturally takes place along this middle line. 376 BOTANY OF CROP PLANTS POMACES 377 Cross-section of Fruit. — In a median cross-section of the apple fruit (Fig. 158), the relation of carpels and receptacle is well made out. The five carpels radiate from the center. Each carpel is composed of a parchment-like endocarp, fleshy mesocarp, and fleshy exocarp. The pith of the re- ceptacle, which is in reahty stem, surrounds and unites with the carpels; the pith is without vascular bundles. Asa rule, there are ten primary vascular bundles seen in the median cross-section. They mark the limits of the pith, all tissue outside of them being cortex of the receptacle. The tissues of the carpels and pith are very similar. How- ever, the tissue of the carpels bears a network of very fine vascular bundles, while that of pith is without such a network. Many observers have wrongly considered all tissue from parchment-like tissue, surrounding the seed cavities, out to vascular ring, inclusive, as carpellary, whereas others have considered only the parchment-like tissue as carpellary. The ten primary vascular bundles are related in their development with the carpels, as is shown by the fact that when six carpels occur there are twelve bundles instead of ten, and when there are four carpels, eight bundles. Longitudinal Section of Fruit. — In longitudinal section (Fig. 158), the flesh is seen to be separated into two parts by a distinct line, the "core line." The core line marks the junction of pith and cortex of the receptacle. The primary vascular bundles of the torus follow the core fine, and branches from them spread out into the cortex of the fruit. Kraus has demonstrated that apple varieties show marked variation in their internal structure, and that this structure is distinctive for any given variety. External Characteristics. — These are very important in technical descriptions of the apple. Form is of considerable consequence. InJ judging form, the apple is held so as to 378 BOTANY OF CROP PLANTS be seen in a line at right angles to an axis from stem end to calyx end. Form terminology includes such terms as round, oblate, conical, ovate, oblong, elliptical, etc. The flower stem persists in the fruit. The depression about the stem is termed the cavity. It varies in shape and depth in the different varieties. At the opposite end from the cavity is the basin. This also varies in character and is of taxonomic value in the classification of fruits. The remains of the calyx are persistent within the basin of the common apple. In the pure Siberian Crabs, the calyx is deciduous, while in hybrid forms of Siberian Crabs and in the common apple it is partly deciduous. The dried stamens and styles may be seen within the calyx lobes. The stamens may be basal, situated near the base of the calyx tube; median, near the middle; or marginal, near the outer edge. The calyx tube itself varies in shape from con- ical to funnel-shaped. The calyx segments, five in number, vary in their arrangement in the mature fruit. They may be divergent, that is, reflexed, erect convergent, when their margins touch, flat convergent, when they are flat and close the tube, and connivent, when they are overlapping. In a median transverse section, the "cells" in different varieties vary in shape and relation to the axis of the apple. They may be "open" or "closed," axile or abaxile. When the walls extend to the axis, the cells are axile, and when they are distant from the axis, and unsymmetrical, they are abaxile. When the core line meets inside the calyx tube, the core is said to be meeting; if near the calyx tube, it__^is clasping. The core outline varies in shape. There are usually two seeds in each cell cavity; however, there may be more than two or fewer or sometimes none at all. They vary in size and color. i»OMACE^. 379 Key to Principal Species of Malus Calyx deciduous from the apex of fruit. Leaves conduplicate in the bud (Fig. loi); petioles thick, usually about i inch long; flowers rose-colored, Mdus jloriliunda (flowering crab). Leaves convolute in the bud (Fig. loi); petioles slender, usually about 2 to 3 inches long; flowers white or very light rose-colored, Malus haccala (Siberian crab). Calyx persistent on the fruit. Leaves glabrous, at least when mature. Leaves prominently lobed, thin, Malus coronaria (American crab- apple). Leaves toothed, but not lobed, thick, Malus angustifolia (narrow- leaved crab-apple). Leaves persistently pubescent or tomentose beneath. Leaves narrowed at base; pomes small, i to i^-i inches in diameter. Pedicels slender, i to i^ inches long, Malus ioensis (Western crab- apple) . Pedicels stout, 3-^ to i inch long, Mains soulardii (Soulard crab- apple). Leaves rounded or subcordate at base; pomes large, 2 to 4 inches in diameter Malus sylveslris (common apple). Malus floribunda, Flowering Craft.— This is a shrub or small tree, often thorny. The leaves are conduplicate in the bud, the flowers abundant, showy, and rose-red, the fruit red, about the size of a pea, and on slender stalks. It is highly ornamental, and flowers in early spring. It is a native of Japan. M. baccata, Siberian Crab. — This crab is a small, spreading tree with leaves that are convolute in the bud, abundant flowers, usually white and showy, and fruit that is }4 to ^i inch in diameter, yellow or red, firm and translucent. The species occurs in many forms. The orchard fruits known as "crab- apples," are believed to be hybrids between this and the common apple, M. syhestris. The Siberian crab grows wild from Siberia to Manchuria and the Himalaya region. M. angustifolia, Narrow-leaved Crab-apple. — It is a low tree with small, narrow, lanceolate leaves, few-flowered cymes, fragrant pink flowers, and fruit about i inch in diameter. It is distributed from Pennsylvania to Tennessee and Florida. M. coronaria, American Crab-apple.— This is a small, bushy tree with thorny, crooked branches, ovate or triangular-ovate, sometimes three-lobed, leaves, large flowers, with a persistent calyx, and fruit that is i to i}i inches in diameter, somewhat flattened endwise, greenish-yellow, waxy, fragrant, and 38o BOTANY OF CROP PLANTS Fig. 159, — Leaves of Malus species. A and B, western crab (M. ioensis) ; C, flowering crab (M. floribunda); D, narrow-leaf crab (M. angustifolia) ; E, Soulard crab (M. soulardi) ; F, common apple (Wealthy) (M. sylvestris); C, American crab (M. coronaria); H, Siberian crab (M. baccata). X M- POMACEiE 381 rich in malic acid. It grows wild in Ontario and North Atlantic States, west to Kansas and Missouri. M. ioensis, Western or Prairie States Crab-apple. — It is a small tree with large leaves, firm in texture and of \arious shapes, large flowers, and green fruit with light-colored spots. It is native of Minnesota, Wisconsin, Illi- nois, Iowa, Missouri, and Kansas. Bechtel's Double-flowering Crab is probably a double-flowered form of Mains ioensis. M. soulardii, Soulard Crab. — This is a natural hybrid between the common apple {M. sylvcslris) and the Western crab-apple {M. ioensis). It is a small, stout tree, with leaves similar to those of M. ioensis, in close clusters on short, densely woolly pedicels; the fruit is larger and of better flavor than that of .\f . i WHS is. It grows wild in the Mississippi Valley. M. sylvestris, Common Apple. — The common apple is a large tree with twigs and under surface of leaves gray-woolly; the flowers are in close clusters, and on short pedicels; the fruit is very variable. There are numerous varieties differing as to form, size, color, and taste of fruit. In order to keep the va- rieties true to type, propagation is vegetative rather than sexual. The common apple is considered to be a native of western Asia and south- eastern Europe. In eastern United States, it occasionally escapes from cul- tivation. It is grown commercially in all parts of the United States except in Florida, the regions bordering the Gulf of Mexico, and warmer portions of the Southwest. The leading apple-growing section of this country is from Nova Scotia south and west to Illinois and Missouri. The Classification of Apples [Mains sylvestris) . — There have been a number of systems of classifying cultivated varieties of apples. A brief sketch of the most important of these is given in the American Horticultural Manual Part II, Systematic Pomology. The principal classifications men- tioned in the above work are those of Johann Jonston, Ger- many 1668, Manger, Germany 1780, Dr. Diel, Germany 1792, Diel-Cochnahl, Germany 1855, Diel-Lucas, Germany 1856, John A. Warder, America 1867, John J. Thomas, America 1849, Robert Hogg, England 1876. The system of Dr. Diel of Germany, was the first to be widely adopted in toto or with modifications. He divided the varieties into seven classes, and these into orders. These classes are as follows: Ribbed apples. Rose apples, Ram- 382 BOTANY Ol' CROP PLANTS hours, Reinettes, Stripelings, Pointlings, and Flat apples. Beach gives the following groups of varieties: Fall Pippin, Rhode Island Greening, Winesap, Fameuse, Alexander or Aport, Wealthy, Duchess of Oldenburg, Northern Spy, Blue Pearmain, and Rails-Genet. Composition. — According to the determinations of Al- wood and Davidson, the average amount of juice recovered from summer apples by grinding and pressing is 53.2 per cent. ; from winter fruit 53.92 per cent. Crab -apples show an average juice content of 57.31 per cent. The average water content of the whole apple varies from 80 to 86 per cent, of its total weight. It is not possible, of course, to remove all the juice from apples by ordinary pressing, and furthermore, the amount of juice recovered depends upon the grinding and pressing methods. The above workers chemically analyzed the juice and pomace of many varieties. The percentage composition of the juice is shown in the following table : specific gravity Total solids Total sugar Invert sugar Cane sugar Acids as! ^^ HsSOi 1 Tannm Summer varieties Autumn varieties Winter varieties. . Crab-apples .049 12.33 .054 I 13.76 .056 : 14.29 .062 15.69 953 10.66 "•43 II . 71 5.85 6.93 7.04 8.08 3 -50 3-53 4. 16 3-45 0.33 0.040 0.36 0.069 0.41 0.050 0.50 0.122 For vinegar-making, a high sugar content is desirable. A common notion is that acid or "tartar" apples are better for vinegar-making than those low in acid. The amount of acetic acid in a vinegar, which is the important test of its quality, is dependent upon the amount of sugar in the juice (cider) and not upon the acid. The sour taste of apples is due to the malic acid present. So-called "sweet apples" do not neces- rOMACEvE 383 sarily contain more sugar than "sour apples," but they do contain less acid, hence their "sweetness." Cider and Vinegar. — Cider is the juice or wine of apples. In the transformation of cider to vinegar, two fermentation processes take place, in the following' order: (i) alcoholic fermentation, and (2) acetic acid fermentalion. When cider "begins to work," it is an indication that the first fermenta- tion process is going on. The sugar of the apple juice is being converted into alcohol and carbon dioxide. The escaping of this gas from the fermenting cider causes a "frothing." The process of alcohohc fermentation is produced by a micro- scopic organism, the yeast plant. When the evolution of carbon dioxide gas has ceased and the alcohol is at its maxi- mum, the cider is spoken of as hard cider. The second step in vinegar-making is the conversion of the alcohol of the hard cider into acetic acid. This change is brought about by a bacterium, the acetic acid germ. The characteristic prop- erties of vinegar are due to acetic acid. Dried Apples. — The output of dried apples in the United States in 1909 was 44,000,000 pounds. Many housewives dry their apples in the sun. When apples are dried on a large scale, they are peeled, cored, and sometimes sliced by machinery. The fruit is then dipped for a few minutes in a weak salt solution, which tends to prevent discoloration. It is then placed in trays and taken to the drying machine. It is the practice in some manufacturing plants to subject the apples, before drying, to sulphur fumes for a short time. These fumes bleach the apples slightly, and also kill any or- ganisms that may be present. The most common drying method is to pass hot air under high pressure over the fruit. After removal from the drying machine, the apples are al- lowed to sweat for several days either in the open air or in well-ventilated chambers. They are then ready for packing. 384 BOTANY OF CROP PLANTS Production of Apples in the United States.— In 191 5 there were produced 230,010,000 bushels of apples in this country, at an average farm price per bushel of 74.6 cents. The ten leading States in the order of their production were New York, Missouri, Ohio, Penzisylvania, lUinois, Virginia, Kentucky, Indiana, Iowa and Michigan. PYRUS (Pear) The characters of this genus are very similar to those of Mains. The pears are trees or shrubs with sipiple leaves, and large flowers in terminal cymes, resembhng those of the >slone cells 'parenchuma celts Fig. 160. — A group of stone cells and surrounding parenchyma cells from the flesh of pear (Pyrus communis). Highly magnified. apple; the styles are usually free to the base. The fruit is a pome, varying in shape, with five carpels, two seeds in each cavity, and an abundance of grit cells in the flesh (Fig. i6c). The two most common species of Pyrus are Pyrus communis, the common pear, and Pyrus serolina culta, sand, Japanese, or Chinese pear. In the common pear, the teeth on the leaves are obtuse, the flowers appear with the leaves, and the calyx is persistent, while in the Japanese or Chinese pear, the teeth on the leaves are sharp-pointed or bristle-like, the flowers appear before the leaves, and the calyx is deciduous. POMACEiE 385 PYRUS COMMUNIS (Common Pear) Stem.^ — The common pear is a tree of upright-growing habit. The flower buds are mixed and terminal, as in most apples. Paddock and Whipple have shown that, in Colorado at least, the Anjou pear may produce blossom buds on one- year-old spurs; that Bartletts may form bloom on the end of the last year's growth; that Anjou, Bartlett, Duchess, and Kieflfer varieties produce bloom in axillary buds on the last year's growth, and that a number of varieties, as Anjou, Bartlett, Duchess and Sheldon, are annual bearers. There are usually from six to nine flowers in a bud. The ''spurs" are similar in appearance and development to those of the apple. Leaves and Flowers. — The leaves are ovate, elliptic, and finely toothed. The flowers are in simple terminal cymes; the pedicels are 2 to 3 inches long, and appear with the leaves; the petals are five in number, rounded, short-clawed, and usually white; the sepals are persistent; the styles are distinct to the base. Fruit.- — The fruit varies in shape, usually tapering to the base; the flesh is with grit cells (Fig. 160) (groups of stone cells imbedded in parenchyma) . Geographical. — The common pear is probably a native of southern Europe and Asia. In many localities, it has escaped from cultivation. There are numerous cultivated varieties. The pear thrives best in the northern half of the United States. PYRUS SEROTINA CULTA (Sand, Japanese, or Chinese Pear) This is a strong-growing tree with broad-ovate, long- pointed .leaves that are very sharply toothed. The large flowers appear before the leaves. The fruit is hard and russet-like, keeps well, and has a deciduous calyx. The tree is a native of China. Chinese Sand, Madame von 386 BOTANY OF CROP PLANTS Siebold/Mikado, and Japanese Sand are a few of the varieties grown in the United States. It is also often used to hybrid- ize with our common pear, the Kieffer variety being the best-known one resulting from such a cross. - Self -sterility in Pears. — The work of Fletcher has pointed out the reasons for the barrenness of many pear orchards. Much of this is due to self-sterility, that is, the inability of the pollen of a variety to fertilize the ovules in the pistils of that variety. It has been frequently observed in many portions of the country that when a certain variety of pear, as well as other fruits, was planted thickly, there was often pro- nounced self-sterility. This is particularly true, it seems, of Bartlett and Kieffer pears. Fletcher obtained the following average results, under Virginia conditions, in self-fertilizing Bartlett, and in crossing with a number of varieties (in the table, the last mentioned variety of a cross furnished the pollen) : Pollinations Av. number of Av. weight of blossoms set mature fruit, ounces Bartlett X Bartlett i in 513 2 .00 Bartlett X Kieffei i in 10 3 .00 Bartlett X Anjou i in 7 3.75 Bartlett X Lawrence i in 9 3 . 50 Bartlett X Duchess i in 10 3 . 50 The following table shows similar relations in the case of Kieffer pears: Pollinations Av. number of blossoms set Kieffer X Kieffer i in 253 Kieffer X Bartlett i in 5 Kieffer X Le Conte i in 7 Kieffer X Lawrence i in 6 Kieffer X Duchess i in 5 Kieffer X Anjou i in 4 Kieffer X Clairgeau i in 3 Kieffer X Garber 1 in 7 POMACEvE 387 From these experiments, Fletcher recommends (under Virginia conditions, at least) that Anjou, Lawrence, Duchess and Kieffer are desirable varieties to plant with Bartlett, and that Bartlett, Le Conte, Garber, Lawrence, Duchess, Anjou, and Clairgeau are desirable varieties to plant with the Kieffer. It is not probable that the same degree of self-sterility for a given variety will prevail under different climatic and soil conditions. Furthermore, it must be held in mind that no immediate eft'ect of strange pollen need be expected in the resulting fruit. Dwarf Pears. — The pear is the most common tree grown in a dwarf form in the United States. The usual method of dwarfing pears is to graft them on quince roots, which are very slow-growing. In a graft, the two plants retain their individuality to a large degree. However, there are numerous instances cited of the influence of the stock upon the scion, or scion upon the stock. ^ When pears are grafted on the more slowly growing roots of the quince, the stock in this case retards the growth of the pear, and dwarfing results. The common quince used in Angers and the varieties ordinarily dwarfed are Angouleme, Bartlett, Anjou, and Louise Bonne. Dwarfing appears to improve the quality of the fruit. 1 If the common apple is grafted on the wild crab, the fruit of the scion growth is more sour than usual. Late varieties of apple may mature earlier when grafted on early stock. The influence of the scion upon the slock is well shown in the case of grafting the morning glory, an annual^ upon the sweet potato, a perennial. In this case, the tuberous roots develop much earlier than usual. A most interesting illustration is the development, in Abutilon, of leaves with white spots (albescent leaves) on a green-leaved scion when grown as a graft upon an albescent stock. 388 BOTANY OF CROP PLANTS CYDONIA (Quince) The genus has much the same characters as Malus and Pyrus, except that each of the five carpels has several seeds, covered with a mucilaginous pulp, and the large flowers are in small clusters or sometimes single at the tips of branches. There are several species of Cydonia, the most common being C. ohlonga (edible quince). CYDONIA OBLONGA (Common Quince) Stem. — The common quince is a small tree seldom over 1 5 feet high, or a shrub, with rather crooked, slender branches. The shoots that come from axillary buds and those that come from terminal buds may give rise to flower-bearing shoots, but it is usually the case that the largest fruit comes on branches arising from axillary buds on the last half of the annual growth. The flowers are not from fruit buds formed in the autumn; after a woody shoot has grown several inches, a flower is produced which terminates the season's growth of that shoot. Leaves. — The leaves are alternate, with blades 2 to 3 inches long, oval, somewhat heart-shaped or rounded at the base, acute at the apex, green above and soft-hairy beneath, and with petioles about ^ inch long. Flowers.^ — As a rule, the flowers are sohtary; the petals are white or hght pink; the stamens are numerous; there are five carpels with several ovules in each cavity. Fruit. — The fruit may be apple- or pear-shaped, hard, woolly when young, becoming smooth with age; the flesh is free of grit cells; the skin is yellow at maturity; each of the five cells of the ovary contains several seeds which have a mucilaginous coating. Varieties. — Bailey gives five varieties of the species. POMACE. E 389 Cydonia vulgaris: Lusitanka, maliformis, pyrijormis mar- morata, and pyramidalis. Uses.- Quinces arc not usually eaten raw but made into marmalades, or canned. The juice is sometimes employed to flavor manufactured fruit products. References Alwood, William B., and Davidson, R. J.: The Chemical Composition of Apples and Cider. U. S. Dept. Agr. Bur. Chem. Bull. 88: 7-18, 1904. Beach, S. A., Booth, N. O., and Taylor, O. M.: The Apples of New York. 22d Ann. Rept. N. Y. Agr. E.\p. Sta., vol. i : 1-409; vol. 2: 1-360, 1903. BiGELOw, W. D., Gore, H. C, and Howard, B. J. : Studies on Apples. U. S. Dept. Agr. Bur. Chem. Bull. 94: i-ioo, 1905. Black, Caroline A.: The Nature of the Inflorescence and Fruit of Pyrus malus. Mem. N. Y. Bot. Gardens, 6: 519-547, 1916. Bradford, F. C: The Pollination of the Pomaceous Fruits. II. Fruit-bud Development of the Apple. Ore. Agr. Exp. Sta. Bull. 129: 1-16, 1915. Brooks, Chas.: The Fruit Spot of Apples. Bull. Torrey Bot. Club, 35: 423- 456, 1908 (includes notes on structure of fruit). BuDD, J. L., and Hansen, N. E.: American Horticultural Manual. Part II, Systematic Pomology. John Wiley & Sons, 191 1. Butler, O.: On the Cause of Alternate Bearing in the .\pplc. Bull. Torrey Bot. Club, 44: 85-95, IQI7- Chittenden, F. J. : Pollination in Orchards. III. Self-fruitfulness and Self- sterility in Apples. Jour. Hort. Soc, 39: 615-628, 1914. Decaisne, Joseph: Memoire sur la famille des Pomacees. Nouvelles Ar- chives du Museum, X, pp. 113-192 (Paris), 1875. Le jardin fruitier du museum, un iconographie de touts les especes et varietes d'arbres fruiticrs cultives dans cet etablisscment. lirmin Didot Freres. Drinkard, a. W.: Fruit-bud Formation and Development. Rept. Vir. Agr. Exp. Sta., 1909-1910: 159-205, 1911. Ewert, K.: Die Parthenokarpie der Obstbaume. Ber. Deut. Bot. Gesell., 24: 414-416, 1906. Die Parthenocarpie der Obstbaume. Ber. Bot. Ges., 26: 414-416, iqo6. Fletcher, S. W.: Pollination of Bartlett and Kieffer Pears. Reprint from Ann. Rept. Va. Agr. Exp. Sta., 1909: 212-232. Pollination of Bartlett and Kieffer pears. Ann. Rept. \'a. .\gr. Exp. Sta., 1909 and 1910: 213-224, 1911. GoFF, E. S. : The Origin and Early Development of the Flowers in the Cherry, Plum, .\pple and Pear. 16th Ann. Rept. Wis. .\gr. Exp. Sta., 200-303, 1899. 390 BOTANY OF CROP PLANTS Investigations of Flower Buds. 17th Ann. Rept. Wis. Agr. Exp. Sta., 266- 285, 1900. Investigation of Flower Buds. i8th Ann. Rept. Wis. Agr. Exp. Sta. 304- 316, 1901. Origin and Development of the Apple Blossom. Am. Gard., 22: 330 and 346-347, 1 90 1. Gardner, V. R., Wagness, J. R., and Yeager, A. F.: Pruning Investiga- tions. Oregon Agri. Exp. Sta. Bull. 139: 1-88, 1916. GouRLEY, J. H. : Studies in Fruit Bud Formation. N. H Agr. Exp. Sta., Tech. Bull. 9: 1-79, 1915. Hardy, J. A., and A. F.: Traite de la taille des arbres fruitiers, ed. 12, 123, Paris. Hedrick, V. P.: Dwarf Apples. N. Y. Agr. Exp. Sta. Bull. 406: 341-368, 1915- Kraus, E. J.: The Pollination of the Pomaceous Fruits. I. Gross Morphology of the Apple. Ore*. Agr. Exp. Sta. Res. Bull. I, pt. I: 1-12, 1913. The Study of Fruit Buds in Oregon. Ore. Agr. Exp. Sta. Bull. 130: 12-21, 1915- Variation of Internal Structure of Apple Varieties. Ore. Agr. Exp. Sta. Bull. 135: 3-42, 1916. Kraus, E. J., and Ralston, G. S.: The Pollination of the Pomaceous Fruits. III. Gross Vascular Anatomy of the Apple. Ore. Agr. Exp. Sta. Bull. 138: 4-12, 1916. Lewis, C. I., and Vincent, C. C: Pollination of the Apple. Ore. Agr. Exp. Sta. Bull. 104: 1-40, 1909. McAlpine, D.: The Fibro-vascular System of the Apple and its Function. Proc. Linn. Soc, N. S. Wales, 36: 613-625, 1911. The Fibro-vascular System of the Quince Fruit Compared with that of the Apple and Pear. Proc. Linn. N. S. Wales, 37: 689-697, 191 2. Paddock, W. and Whipple, O. B.: Fruit Growing in Arid Regions. Mac- Millan Co., 1910. Pickett, B. S.: Factors Influencing the Formation of Fruit Buds in Apple Trees. Trans. Mass. Hort. Soc, pt. I: 57-72, 1913. Sandsten, E. p.: Some Conditions Which Influence the Germination and Fertility of Pollen. Wis. Agr. Exp. Sta. Research Bull. 4: 149-172, 1909. Shaw, J. K. : The Technical Description of Apples. Mass. Agr. Exp. Sta. Bull. 159: 73-90, 1914. Waite, W. B.: The Pollination of Pear Flowers. U. S. Dept. Agr. Div. Veg. Path, and Phys. Bull. 5: i-iio, 1894. West, G. H.: The Pollination of Apples and Pears. Trans. Kans. State Hort. Soc, 32: 38-50, 1912. CHAPTER XXVIII DRUPACE^ (Plum Family) Habit, Stems. — Representatives of the plum family are trees or shrubs. The bark exudes a gum, and the leaves, bark, and seeds are bitter, and contain prussic acid. Many cases of poisoning have been recorded from eating the seeds of peach and bitter almond, and it is also known that stock is poisoned from eating the leaves of wild cherries. The glucoside, amygdahn, acted on by emulsin, an enzyme, in the presence of water is changed to prussic acid, grape sugar, and benzaldehyde. Prussic acid is deadly poisonous even in small amounts. Leaves.- — The leaves are alternate, petioled and com- monly finely toothed. The teeth and petiole are often glandular (Fig. i6i) ; the stipules are early deciduous. Flowers. — The perfect, regu- lar flowers (Fig. 162) are solitary (apricot), or in racemes (wild black cherry, etc.), umbels (sweet cherry, etc.), or corymbs (perfumed cherry). The calyx is free from the ovary, five-lobed, bell-shaped or 391 Fig. 161.— Leaf of peach (Amygdalus persica). The base of the leaf considerably enlarged, in B. 392 BOTANY OF CROP PLANTS tubular and with its lobes imbricated in the bud; the corolla has five distinct petals; there are numerous stamens. In a Fig. 162. — Floral diagram of Prunus. iepa\ ^ nm oj receptacle st\jle Fig. 163. — Sour cherry (Prunus cerasus). Median lengthwise section of flower. longitudinal section (Fig. 163) of the drupaceous flower, it is seen that the ovary is placed down within a cup commonly URUPACEiE ^9^ called the "calyx tube." If it is a calyx tube, then petals and stamens are inserted upon it. It is very probable that this tube is receptacle and that calyx, corolla and stamens are mounted thereupon. There is one pistil, situated at the bottom of the hollow receptacle; the ovary is one-celled and two-ovuled; the style is single and terminal and bears a small, head-shaped stigma. 005/1/ on of epicarp ~\mesocarp endocarp * or ' 'stone' Fig. 164. — Median lengthwise section of young cherry fruit (drupe). Fruit.- — The fruit is a drupe (Fig. 164), that is, one with a single seed surrounded by a stony endocarp, fleshy meso- carp, and an outer skin or exocarp (epicarp). However, if one examines the young ovary of a Prnnns flower he will find 394 BOTANY or CROP PLANTS two oviiles; one of them aborts, the other develops into a seed. The endosperm is absent, or present only in a small amount. The cotyledons are fleshy. The only genus of any importance is Prunus. It has the characteristics of the family. PRUNUS This genus includes the plum, cherry, almond, peach and apricot. These main groups may be distinguished by the following key: Key to Main Groups of Genus Prunus Stone smooth. Flowers clustered; fruit glabrous. Fruit large, usually grooved, covered with a bloom; stalk short; stone usually compressed, longer than broad; leaves convolute in the bud (Fig. loi), Plums. Fruit small, usually not grooved, not covered with a bloom; stalk long; stone usually globular; leaves conduplicate in the bud (Fig. loi), Cherries. Flowers solitary or in two's; fruit velvety at first, Apricots. Stone pitted or furrowed. Flesh soft, thick, juicy. Peaches. Flesh hard, thin, dry, Almonds. The genus has about 90 species, nearly all of which occur north of the equator; they are widely distributed in both eastern and western hemispheres. Most species are con- fined to the temperate zone. The evergreen cherries include a group found in the tropics and subtropics. PLUMS Stems. — The plums are shrubs or small trees. The different species vary considerably in bark and twig charac- ters. The bark of southern forms is lighter in color than that of those growing in the north. Plums have a tendency DRUPACE^ 395 to produce spurs (Fig. 165). Flower buds are, as a rule, on these spurs, one spur bearing from 2 to 20 buds. The spur may terminate in a leaf bud. However, in most plums, true terminal buds are seldom formed. In such cases, if the last lateral bud is a branch bud, this continues the growth of the branch in a straight Kne. The line between the two seasons' growths is not as sharp, in this case, as when a terminal bud develops. If the last lateral bud is a flower bud, the twig usually dies back to the lateral branch developed from the last branch bud. In all plums, the flower buds are lateral. Flower buds usually stand out at an angle of about 30°, while leaf buds are more appressed to the stem. Leaves. — The leaves of plums vary a great deal in size, form, color, surface, thickness, and margin. In some species, the serrations are tipped by glandular prickles. Stipules are present. The leaves are convolute in the bud (Fig. lOl). Inflorescence. — The flower buds of the plum, unhke those of the apple and pear, bear only flowers. They may break open before, simultaneously with, or after the leaf buds. The flowers are in fascicled umbels. The number of flowers in the bud varies from one to five, two and three being the most common numbers. Flowers. — The receptacle forms a hollow cup (Fig. 163). Fig. 165. — Twig of Domestica plum (Prunus domestica). {After Paddock and Whipple.) 396 BOTANY OF CROP PLANTS On its edge, are arranged five sepals, five petals, and fifteen to twenty stamens. There is a single pistil bearing one style and one stigma. The pistil is at the bottom of the recep- tacle. There are two ovules in the young ovary; one of them aborts during maturation of the fruit. Fertilization.-^Many of the plums are practically self- sterile. The native plums exhibit the greatest self-sterility; this is due to the impotency of the pollen when used on the stigma of the same flower. Japanese and domestic plums are less self-sterile than native species. In some cases, not only are pistils developed that are so weak as to fail even if polli- nated, but some flowers do not form pistils. Again, pistils and stamens of the same flower often mature at different times. Usually, the pistils mature first. Rarely, the opposite is the case. Hence it is seen that cross-fertilization is very nec- essary in plum ori:hards, but not only cross-fertilization be- tween different trees of the same variety but between dif- ferent varieties. It is reported by Hendrickson that French and sugar prunes in California set a very light crop unless a large number of bees are present in the orchard at the time of blooming. They appear to be self-sterile to some extent. Imperial prune trees that were enclosed in a tent from which all insects were excluded set no fruit. It seems that, with the Imperial prune, fruit is not set unless pollen is brought from other trees. It is distinctly self-sterile. All Prunus species are insect-pollinated for the most part. Fruit. — After fertihzation, the receptacle, with its attached sepals, petals, and stamens, is cut off by a circular abscission layer near its base (Fig. 164). The ovary wall increases in thickness to form the following fruit parts (Fig. 164): (i) skin, exocarp; (2) flesh, mesocarp; and (3) hard stony layer about the seed, endocarp. The style and stigma do not per- sist in the fruit. The seed is within the endocarp. Hence DRUPACE/E 397 the slone ("pit") of the plum consists of hardened endocarp, seed coat, and eml)ryo. 'J'he stone is compressed. Classification of Plums.— For a complete description of the species of plums in American plum culture, see ''The Plums of New York"; Hedrick, Report of the N. Y. Agr. Exp. Sta., vol. 3, pt. II, 191 1 ; and Wight, W. F., "Native American Species of Prunus," Bull. 179, B. P. I., 1915. Key to Principal Species of Plums * Flowers in clusters of one or two (three in P. Iri flora), Old World Plums. Shoots and pedicels pubescent. Fruits large, more than i inch in diameter, variable in shape, often compressed; tree large; stamens about 30, P. domestica. Fruits small, less than i inch in diameter, uniformly oval or ovoid; tree small, compact; stamens about 25, P. insUitia. Shoots glabrous or soon becoming so, pedicels glabrous. Flowers mostly single, P. cerasifcra. Flowers in threes, P. triflora. Flowers in clusters of three or more, rarely two, American Plums. Leaf serrations glandless, acute; caly.x lobes entire, glabrous on the outer, pubescent on the inner surface, not glandular, P. americami. Leaf serrations glandular (at least when they first unfold), rounded or ob- tuse; caly.x lobes glandular (except in P. angusiifolia). Leaves broad, mostly oblong-ovate or obovate, the margin often doubly serrate; flowers 2 to 2.5 centimeters broad; catyx with a reddish tinge, at least when old, the lobes glandular serrate, P. nigra. Leaves narrow, ovate, ovate-lanceolate, the margin rarely doubly serrate; flowers 8 to 15 millimeters broad; calyx rarely reddish, the lobes entire, either glandular or glandless. Leaves thick, slightly lustrous on upper surface; veins conspicuous below; margin coarsely and irregularly serrate, P. horlulana. Leaves usually thin, lustrous on upper surface, veins not conspicuous below, margin finely and evenly serrate. Leaves usually 6 to 10 centimeters long; calyx lobes glandular, P. munsoniana. Leaves 2 to 6 centimeters long; calyx lobes glandless, P. angusiifolia. * Adapted from The Plums of New York by Hedrick. 39^ BOTANY OF CROP PLANTS DISCUSSION OF SPECIES Prunus domestica. — This is a vigorous-growing tree which may reach a height of 30 or 40 feet. The leaves are ovate or obovate, elliptical or oblong-elliptical; the upper surface is smooth, the lower often finely hairy, the margins coarsely toothed, and the teeth often glandular. The flowers usually appear after the leaves, sometimes with them. The fruit is generally globular, the skin varies in color, the flesh is yellowish, and the stone free or clinging. This is the best known and most widely distributed species of plums. It has been cultivated for 2,000 years, originally coming from about the Caucasus Mountains. The first colonists brought varieties of this species to North America. There are now over 950 varieties of Domestic plums grown in this country. These have been divided into a number of groups, largely based upon fruit characteristics. These groups are as follows: 1 . Green Gages (Reine Claude) .- — These are low trees with dark bark which cracks deeply, with leaves doubly toothed, fruit relatively small, round, mostly green or golden, and of excellent quality. The stone is either free or clinging. Important varieties are Reine Claude, Bavay, Spaulding, Yellow Gage, Washington, etc. 2. Prunes. — A prune is any plum that can be cured without removing the pit. All plums with a large percentage of sugar make good prunes. The fruit is large, oval, usually com- pressed, blue or purple, and with a firm, greenish, yellow, or golden flesh, and free stone. Prunes are raised on the Pacific Coast. The industry there has become a large one. Im- portant varieties are Italian, German, Agen, Tragedy, Ten- nant. Sugar, Giant, Pacific, and Ungarish. Preparation of Prunes. — In the preparation of prunes, the DRUPACE^ 399 plums are first cleaned, and their skins ruptured to permit of more rapid drying. Usually, they are dipped into boiling water or hot lye, which not only cleans but also cracks the skin. They are then dried in the open sun, or in drying sheds where artificial heat may be utilized. After drying, the prunes are allowed to "sweat" for two or three weeks. They are then graded and "glossed" or finished by heating in steam or immersing in salted boihng water, glycerine or fruit juice. This gives the surface of the prunes a shiny appearance, and also sterilizes the exterior. 3. Peridrigon Plums. — This is a prune plum grown only in France. 4. Yellow Egg Plums. — The fruit of these is large, in fact the largest of plums, long-oval, and has a yellow or purple skin, and yellow flesh. Well-known varieties are Yellow Egg, Red Magnum Bonum, Golden Drop, and Monroe. 5. Imperatrice Plums. — These are medium-sized, dark blue plums, with thick skin, firm flesh, and clinging stones. Such varieties as Ickworth, Arch Duke, Monarch, Shipper, Arctic, etc., belong to this group. 6. Lombard Plums. — This group includes the reddish or mottled varieties of Domestic plums. Lombard, Bradshaw, Victoria, Pond, and Duane are well-known varieties. Pninus insititia.— This is a small tree not over 25 feet high with smaU ovate or obovate, finely toothed leaves which are usually glandular; both surfaces of the leaves are slightly hairy. The flowers are usually in lateral, umbellate clusters. The fruit is globular or oval, small, usually bluish black or golden yellow, and has yellow flesh, and a clinging or free stone. Varieties of this species are hardy and thrifty. The species has been in cultivation over 2,000 years, but in all that time has shown but little variation. Insititia plums rank second 400 BOTANY OF CROP PLANTS to Domesticas. The species grows wild from the Mediterra- nean northward into Norway, Sweden and Russia. Insititia plums fall into four groups as follows: 1. Damsons. — These are spicy plums, mostly sour, and much desired for preserving. 2. BuUaces.- — This group contains a few varieties differing but little from the preceding group, except as to fruit shape. The Bullaces are spherical. 3. Mirahelles: — These are round, yellowish or golden plums with a free stone and resemble much the green gages as to quality. 4. St. Juliens.- — This is a name appHed to a group of plums resembHng the Damsons. They were formerly used in this country as stocks. Prunus cerasifera. — These are the cherry or Myrobalan plums. They are hardy, thrifty varieties, free from disease, readily adaptable and most suitable for hybridizing. The trees are small, bloom profusely, and bear a small, round, cherry-like plum from 3'^ to i inch in diameter. They are adapted to ornamental usage. They are also used as stocks upon which to bud other plums. Prunus trifiora. — These are the Japanese plums; they are not cultivated in many parts of the world. They are native of China. It is a highly adapt- able group, vigorous, productive, early-bearing, and disease-free. Varieties are, for the most part, cling stones. Prunus americana.— This is our most important native plum. It grows wild from New Mexico to Manitoba, and eastward to the Atlantic Coast. Not being able to raise European plums in the Mississippi Valley, Americans domesticated the native American plum. Varieties of this species are hardy. The American plum tree is usually small, with rough, shaggy bark. The fruit is reddish or yellowish. Altogether, there are about 260 varieties of the americana. Waugh finds that they often bear defective pistils or stamens, or that they are often protandrous or protogynous. From his observations, he recommends some provisions for cross-fertilization when planting americanas. Prunus hortulana. — This species includes a number of plums well suited for jelly, preserves, and spicing. They are very free of suckers. Important varieties are American, Golden, Juicy, Ruby, Waugh, and Gonzales. The Hortidanas are adapted to the Southern States. DRUPACE^ 401 Pninus nigra.— This is the most northern of American plums. It is well adapted to the States along the Canadian border. Pninus munsoniana. — This is the plum most grown in the South. The varieties are mostly cling stones. Of all plums, these are most in need of cross-pollination. A few of the chief varieties arc Robinson, Newman, Wild Goose, Arkansas, and Downing. Pninus angustifolia. — The Chickasaw plum is a small tree, 6 to 10 feet high, sometimes shrubby. The fruit is small, almost globular, flesh yellow, and of good quality. It ranges from Delaware to Louisiana and westward to Arkansas and Texas. Its varieties do well in the Southern States. The two subspecies, watsoni and varians, have varieties of some horti- cultural value, such as Purple Panhandle, .\frican, Clark, Emerson, etc. CHERRIES corolla —leaf hud ^rowm scar Description. — The cher- ries resemble plums in many respects. The bark of the- cherry separates in rings. The flower buds are usually found on short spurs (Fig. 166). In some sour cherries, however, axillary flower buds occur on long, strong shoots. These buds produce fruit the following spring. Since the lateral buds in such shoots are flower-bearing, no lateral branches are pro- duced, and the result is a long, naked branch. On the spurs, the flower buds are axillary and a branch bud terminates the short shoot. The flower buds bear only flowers and no leaves (except very rudimentary ones which persist but for a short time). There 26 scales rowln growth Fig. 166. — Spur of sour cherry (Prunus cerasus). 402 BOTANY OF CROP PLANTS are from two to live blossoms, usually two, in each bud. The flowers are in umbels, as a rule. The flowers and fruit of cherries are, morphologically, similar to those of plums. The leading commercial varieties of cherries grown in Cahfornia have been shown to be self-sterile. It is altogether possible that steriHty in cherries is widely spread. Groups of Cherries.— According to Bailey the principal cultivated cherries are from two species, Prunus avium, the sweet cherries, and Prunus cerasus, the sour cherries. PRUNUS AVIUM (Sweet Cherry) Description. — The sweet cherry is a tall tree, strong-grow- ing, long-lived, and frequently attains a diameter of i foot or more. The bark is gray-brown, the outer layer often being roughened; lenticels are inconspicuous. The leaves are thick, oval, ovate or obovate, 4 to 12 centimeters long, abruptly short-acuminate, irregularly- and coarsely toothed, or doubly so, green and smooth above, hghter beneath, slightly hairy on the veins, more or less drooping, and with long slender petioles. Flowers appear with the leaves, in lateral, sessile umbels; the flower pedicels are 3 to 6 centi- meters long; the petals are white, and the stamens 35 or 7,6. Self-sterihty has been reported in the sweet cherry orchards of the Northwest. The fruit is variously colored, spherical to heart-shaped, with flesh soft or hard, usually sweet, and with the skin adherent to the flesh. Geographical. — The species is a native of Europe. It has been cultivated in this country for many years, and in some places has escaped from cultivation. Groups of Sweet Cherries. — The sweet cherries include four general groups: I. Mazzards. — The fruit is small, and varies in shape and color. Mahaleb and mazzard stocks are the two common DRUPACEiE 403 sorts upon which sweet cherries are grafted, the results being somewhat better when grown on mazzard stock. Sour cher- ries are also propagated on mazzard stock. 2. Hearts (Geans). — The fruit is heart- shaped and has a soft flesh. Tartarian, Black Eagle, etc., are varieties in this group. 3. Bigarreaus. — The fruit is heart-shaped, light or dark in color, and with hard flesh. Common black varieties are Windsor and Schmidt, common light ones, Yellow Spanish and Napoleon. 4. Dukes. — Dukes resemble the Hearts in shape and color, but have a juice somewhat acid. Dukes are often classed with the sour cherries, but Bailey would class them with the sweet cherries on account of the habit of growth of the trees, and the flower and leaf characters. Hedrick considers Duke cherries as hybrids between Prunus avium and F. cerasus. They resemble sweets more than sour. Dukes commonly produce sterile seed. There are both dark- and light-colored sorts. Reine Hortense and May Duke belong here. PRUNTJS CERASUS (Sotir Cherry) Description. — Sour cherry trees are smaller than those of sweet cherries. They "sucker " readily from the root. The bark is gray- brown and quite smooth; lenticels are con- spicuous. The leaves are thick, ovate or ovate-lanceolate, abruptly acute or acuminate at the tip, variously toothed, becoming smooth on both surfaces, usually erect, and with short, strong petioles. Flowers appear before Fig. 167.— TwiR of sweet cherry (Prunus avium). (After Paddock and Whipple.) 404 BOTANY OF CKOl' PLANTS or with the leaves in small umbels from lateral buds; the pedicels are about 24 centimeters long; and the stamens are about 30 in number. The fruit is globular, always red, with soft flesh and skin that usually separates readily from pulp. Geographical. — The species is a native of Europe and an occasional escape from cultiva- tion in this country. Groups of Sour Cherries.— The sour cherries include two general groups: 1. Amarelles. — These cherries are pale red in color, have colorless juice, and are generally somewhat flattened on the ends. They have less acid than dark- colored cherries. Montmorency and Early Richmond are the most common Amarelles. 2. Morellos or Griottes. — These are cherries with dark red fruit and dark juice, and they vary from spherical to heart-shape. Common varieties are Ostheim, Olivet, Louis Philippe, and the Morello. Other Species of Cherries. — The species of cher- ries native to America are of little horticultural importance. Chief of these are P. pennsylvanica, P. cmarginata, P. pumila, P. cuneata, and P. hcsscyi. P. pemisyhanica is sometimes used as a stock on which to bud the sour cherry. Pruniis mahaleb, a native of Europe and Asia, is very extensively used in this country as a stock for all sweet and sour cherries. It is an excellent dwarfing stock. Uses. — Both sour and sweet cherries are used as a dessert fruit, and in the making of pies. The bulk of the cherries Fig. 168. — Twig of sour cherry (Prunus cerasus). (After Pad- dock and Whipple.) DRUPACE^ 405 grown for canning purposes are sour red sorts, and are pro- duced in New York, Michigan, Wisconsin, and California. Maraschinos are sweet cherries, most of which are imported from Italy and Spain. A Californian variety, Napoleon, is also used to some extent for this purpose. Recent investiga- tions point to the conclusion that a number of commercial products may be obtained from cherry pits and cherry juice, two by-products of the cherry industry. The fixed oil expressed from the fresh kernels is much like almond oil, and can be utilized in similar ways. Also, the volatile oil is quite similar to bitter-almond oil, and can be used in the same way. The pressed cake, that which remains after the oils are re- moved, may be ground into a meal and used as a feeding stufif. The waste cherry juice can be changed into syrup, jelly and alcohol. APRICOTS Stems. — The common apricot varieties belong to the species Prunus armeniaca. The trees are small, round- topped, and resemble the peach tree. As in the plums, true terminal buds are seldom formed. Lateral branch buds and flower buds are found together in the axils of leaves (Fig. 169). Except for a few rudimentary leaves, the fruit buds bear only flowers. Normally, there is but one flower (some- times two) in a bud; they appear before the leaves. The flower buds, which are lateral, occur singly at nodes; often three buds are developed in the axil of a leaf, the central one being a branch bud, while the two laterals are flower buds. However, not all branch buds on a twig are accom- panied by flower buds. The vigor of the tree and twigs, and pruning methods will determine the position of the latter, to some extent. In strong-growing twigs, the flower buds are rather near the tip of a year's growth; on twigs of moderate 4o6 BOTANY OF CROP PLANTS growth, they will be found along the central portion of the twig; while on feeble-growing branches, they usually occur singly, and are quite evenly distributed along the entire length. However, not all the flower buds are formed on the long shoots. Many are developed on ex- tremely short spurs, but always axillary; usually the flower buds are single in such short growths. Leaves.^ — These are usu- ally ovate, often somewhat heart-shaped at the base, abruptly short-acuminate, smooth above, slightly hairy beneath, finely t o ot h e d , on glandular petioles, and convolute in vernation. Inflorescence and Flowers.^The flowers are soHtary or in pairs, pink- ish, sessile or nearly so. Morphologically, the flowers are similar to those of plum, cherry and other Prunus spp. Fruit. — This is much like a peach in color and shape; the skin is velvety at first, but becomes smooth at maturity; the flesh is always yellow. The stone (endocarp and seed) is flat, smooth, and grooved on one edge. In the maturing of the fruit, the Fig. 169. — Twigs of apricot (Prunus armeniaca). (After Paddock and Whipple.) DRUPACE^ 407 parts of the flower are cut off by a basal ring of growth, as described in the plums. Distribution. — The species is considered to be a native of southern Asia. It is now cultivated in most temperate climates. In the United States, the practice is to graft apricots on to the roots of plum or peach. Other Species. — There are several other species of apricots besides P. armeniaca, but none of them bear fruit of marketable size. They are generally planted as ornamentals. Among such are P. sibirica, the Siberian apricot, P. dasycarpa, the purple or black apricot, and P. mutne, the Japanese apricot. Uses. — Apricots are prized as a table fruit, both in the fresh and the dried con- dition. They are usually pitted before they are dried, but may be dried with the skins ofif or on. "Sulphuring" may pre- cede the drying process proper. Almond oil is derived from the seeds. PEACHES The common varieties of peaches come from one species — Prunus persica. Some writers place the peach in a separate genus, Amygdalus persica. The latter is the name given to the peach by Linnaeus. Stems. — The tree is low, seldom over 25 feet in height, broad-topped, and with a scaly, dark brown bark. Young twigs are glossy green. The flower buds of the peach are simple, containing only flowers, or flowers and a few rudimentary leaves; each bud has one, sometimes two, flowers. The flower buds are borne singly or in pairs with Fig. 170. — Twigs of peach (Prunus persica). (After Pad- dock and Whipple.) 408 BOTANY OF CROP PLANTS a branch bud (Fig. 170). In this respect, they are similar to the apricot. Leaves.- — These are conduphcate (Fig. loi) in the bud, elHptic to lanceolate or oblong, and taper toward either end; they are finely and sharply toothed, and on stout petioles. Inflorescence and Flowers.— The flowers are normally solitary in the axils of leaves and appear before the leaves; they are large, pink, fragrant, and showy. Fruit.^ — The fruit is subglobular, grooved slightly on one side, has velvety skin, and hard flesh which may be free (freestones) or adherent (clingstones) to the stone. The st6ne is compressed, pointed, and pitted. The seed is of the shape of an almond, aromatic, and sKghtly bitter. Geographical. — The peach is a native of Asia, probably China. It was in- troduced into Europe at a very early date, coming by way of Persia. This fact accounts for the specific name, persica, and common name, peach. The tree is now cultivated in temperate regions. Occasionally it is escaped from cultivation, especially throughout our Northern and Middle States. Types of Peaches. — The first system of classification of peaches was worked out by Onderdonk, of Texas. He divides the varieties of peaches into five classes or races, based primarily upon the country in which they originated, hence upon their range of adaptability. 1. Peen-to Race. — The stone is almost spherical (Fig. 171, C, D). somewhat compressed at the end, and with small and round corrugations; the fruit (of original peen-to) is much flattened; the skin is white, blotched with red, and flesh white; the stone is free or cling. It is adapted to subtropical regions. Varieties: Angel, Clara, Hall, Waldo. 2. South China Race ("Honey" Group). — The stone is oval (Fig. 171, B), and its corrugations sUght; the fruit is sHghtly flattened, with a pecuhar long, conical apex more or less recurved, small, oval, and has a very deep suture at DRUPACE.E 409 the stem end; the flesh is juicy, firm, generally white; the stone is free or chng. It is adapted to subtropical condi- tions. Varieties: Climax, Imperial, Pallas, Taber. 3. Spanish Race. — The stone is large, oval, nearly flat (Fig. 171, A), its apex prominent, and corrugations small; the fruit is large, yellow, or yellow streaked with red. It is adapted to southern conditions. Varieties: Cabler, Druid, Onderdonk, Texas. Fig. 171. — Fruit of the races of peaches. .4, Spanish Race; B, South Chin- ese Race; C, Peen-to Race; D, stone of Peen-to Race; E, Persian Race; F, stone of Persian Race; G, North Chinese Race. {After Price, Texas Agr. Exp. Sta.) 4. North China Race C' Chinese Chngs")- — The stone (Fig. 171, G) is globular, thick, its corrugations not at all promi- nent, cling, semi-cling or free; the fruit is large, almost glob- ular, and its flesh is fine-grained and juicy. It has a wide range of adaptability. Varieties: Belle, Lee Ray, Superb. Elberta and several other varieties are considered crosses between the North China and Persian races. 41 BOTANY OF CROP PLANTS 5. Persian Race. — The seed is globular, with corrugations prominent toward the apex (Fig. 171, E, F) ; the fruit is much Hke the preceding. The common varieties of peaches grown in northern orchards belong to this race. Varieties: Crothers, Foster, Late Crawford, Reeves, Salway, Walker. In addition to the above, the Nectarine should be added as a variety of peach. It differs from the common peach in that its fruit is smaller, the skin is smoother, and the leaves are commonly more prominently toothed. There are both freestone and clingstone nectarines. It is known that nectarines appear on peach trees and peaches on nectarine trees. Such fruits that thus appear are evidently "bud variants." Uses, and Production of Peaches in the United States. — The fruit is used largely as a dessert, both fresh, dried and canned. Peach-es are usually pitted before they are dried. The seeds of the peach, as well as those of almond, apricot and plums, contain both fixed and volatile oils, which are of commercial value. There are peach interests of commercial importance in a large proportion of the States. The total output of peaches for the country in 191 5 was 64,218,000 bushels, which were sold at an average farm price of 81.1 cents. California led in production, with 9,768,000 bushels. The other nine lead- ing States, in the order of their output, were Arkansas, Georgia, Texas, Missouri, Alabama, Kansas, Tennessee, Oklahoma and Ohio. ALMONDS Description.— The common almond is Prunus amygdalus (Amygdalus communis). The tree is much like the peach in shape and size. The flower buds are axillary along with branch buds, as in the peach and apricot. The leaves are DRUPACE^ 41 1 lanceolate, firm, shining, and finely toothed. The flowers are normally solitary and appear before the leaves. They are large, pink, and showy. Many varieties are sterile without cross-fertilization. The drupe is much compressed. The mesocarp (portion corresponding to the flesh of peach or plum) is leathery and tough and separates readily at maturity from the stone (endocarp and seed). The "unshelled" almond of commerce consists of the thin, pitted, light-colored endocarp, within which is the seed or "kernel." The common almond is a native of Asia. Types of Almonds.- — The two general types or races of common almonds are the hitter and the sweet. The difference is in the composition and taste of the kernel. The sweet or edible almond^ consist of two groups: Hard-shell and soft- shell. The latter are of the greater economic importance. In addition to the common almonds, Prunus amygdalus, there are a number of dwarf forms which are grown mostly as ornamentals. Uses. — Almonds are grown for the nuts which are used directly as a food. Almond oil finds use in the manufacture of flavoring extracts. The seeds are also a source of prussic acid. Almond Oil.- — Most of the so-called oil of almonds is derived from the seeds of the apricot; almond and peach seeds also furnish a considerable quantity. The oils from these three sources are very nearly the same. In the process of extracting almond oil, the seeds are ground, subjected to great hydraulic pressure to remove the undesirable fatty oil, and the residue ground again, fermented, and distilled with steam. The distillate is almond oil and hydrocyanic acid. This latter, deadly poisonous substance is removed by treating the mixture with lime and copperas. 412 BOTANY OF CROP PLANTS References Bailey, L. H: Fourth Report on Japanese Plums. Cornell Exp. Sta. Bull. 175: 131-160, 1899. B.^iLEY, L. H., and Powell, G. H.: Cherries. Cornell Agr. Exp. Sta. Bull. 98: 471-500, 1895. Earle, F. S.: Japanese Plums. Ala. Agr. Exp. Sta. Bull. 85: 423-448, 1897. Gardner, V. R.: A Preliminary Report on the Pollination of the Sweet Cherry. Ore. Agr. Exp. Sta. Bull. 116: 1-40, 1913. Goethe, R.: tjber die Klassification der Pfirsichsorten. Gartenflora, 55: 169-182, 1907. Gould, H. P.: Growing Peaches: Varieties and Classification. U. S. Dept. Agr. Farmers' Bull. 633: 1-18, 1914. Hedrick, V. P.: The Cherries of New York. 2 2d Ann. Rept. N. Y. Agr. Exp. Sta., vol. 2, part 2: 1-371, 1915. The Plums of New York. i8th Ann. Rept. N. Y. Agr. Exp. Sta., vol. 3, part 2: i-6i6, 191 1. The Blooming Season of Hardy Fruits. N. Y. Agr. Exp. Sta. Bull. 407: 367-391, 1915- Hekdrickson, a. H.: The Common Honey Bee as an Agent in Prune PolHnation. Calif. Agr. Exp. Sta. Bull. 174: 127-132, 1916. Hume, Harold H.: The Peen-to Peach Group. Fla. Agr. Exp. Sta. Bull. 62: 505-519, 1902. Onderdonk, Gilbert: Report of the Commissioner of Agr., 1887, pp. 648- 650. Containing the Original Classification of the American Varieties of Peaches. Powell, G. Harold: The Chinese Cling Group of Peaches. Del. Agr. Exp. Sta. Bull. 54: 1-32, 1902. Price, R. H.: The Peach. Tex. Agr. Exp. Sta. Bull. 39: 803-848, 1896. Quaintance, a. L.: The Development of the Fruit Buds of the Peach. Ga. Exp. Sta. Rept. 13: 349-351, 1900. Rabak, Frank: Peach, Apricot, and Prune Kernels as By-products of the Fruit Industry of the United States. U. S. Dept., Bur. Plant Indus. Bull. 133: 1-34, 1908- The Utilization of Cherry By-products. U. S. Dept., Bur. Plant Indus. Bull. 350: 1-24, 1916. Reimer, F. C: The Honey Peach Group. Fla. Agr. Exp. Sta. Bull. 73: 135- 153, 1904. Wight, W. F.: Systematic Botany of the Plum as Related to the Breeding of New Varieties. Ann. Rept. Am. Breeders' Assn., 8: 488-497, 191 2. The Varieties of Plums Derived from Native American species. U. S. Dept. Agr. Bull. 172: 1-44, 1915. Native American Species of PrM«w5. U. S. Dept. Agr. Bull. 179: 1-75, 1915- CHAPTER XXIX LEGUMINOS^ (Pea Family) The pea family is one of wide geographical distribution, occurring both in temperate and warm cHmates. According to Piper there are about 487 genera and 10,782 species in the family. Of these, 3,846 species in 103 genera are American. "Legume''' is a popular name applied to members of the Leguminosaj. Probably no family is of greater agricultural importance than this one, unless it is the Graminefc. Legu- minous plants are comparatively rich in protein; this applies to all portions of the plant, and not to seeds alone. For this reason they help to balance the food ration of man and of domestic a^nimals, which is quite largely made up of starchy foods, such as are furnished by the cereal crops. Further- more, the fact that legumes are rich in nitrogenous sub- stances makes them of value as fertilizer crops. Moreover, they leave a considerable quantity of vegetation behind them when harvested, and thus add humus to the soil, which improves both the chemical and physical properties of the soil. Root Tubercles. — The roots of the legumes support the growth of a bacterium (Fseudomonas radicicola) which forms upon them abnormal growths called nodules or tubercles. The tubercles are root colonies of the above organism, which stimulates rapid growth of certain root cells and hence the formation of swollen, gall-like structures. These organisms have the power of fixing free nitrogen of the air. That is, free nitrogen gas from the soil air is taken by the organism 413 414 BOTANY OF CROP PLANTS and, together with other chemical elements, made a part of its protein. It is probable that the legume bacteria, while active in the nodule, are throwing off continuously nitroge- nous substances which are absorbed directly by the plant upon which they are growing. Moreover, when the nodules decompose, their protein contents are ammonified, and nitrified, and finally there is left in the soil, nitrates which are available as a source of nitrogen for green plants. Legumes are regularly employed as rotation crops with cereals, and root crops. Since they are heavy soil feeders, they make excellent crops to plow under. Habit. — Leguminosae are either annual, biennial or peren- nial; and are either herbs (peas, beans, alfalfa, etc.), shrubs {Genista, dye-weed or green- weed), or trees {Rohinia and Gleditsia, locusts), and a very few are vines {Vicia spp., vetches). Leaves.— These are alternate on the stems, stipulate, and mostly compound. They are generally odd-piimate, that is, a leaflet terminates the rachis of the leaf, as in Rohinia (locust). Astragalus (vetches) dm&Aragallus (loco); sometimes they are even-pinnate, that is, terminated by a tendril or bristle, as in Vicia (vetch) and Lathyrus (wild and sweet peas) ; or they may be trifoliate, as in clovers, or digitate, as in Thermopsis (buckbean). Liflorescence. — The flowers are nearly always arranged in racemes (pea), sometimes in a head (clovers), or spike-like raceme (alfalfa), or spike (Glycyrrhiza, licorice). Flowers.^ — These are irregular (Fig. 172); they have a butterfly-hke shape, and for this reason, flowers of the pea type are often spoken of as "papilionaceous." The calyx is normally four- to five-toothed or cleft, the teeth or lobes being equal or unequal. The petals are usually five in number, a broad upper one {standard, banner or vexillum), LEGUMINOS^E 415 two lateral ones {wings or alec), and two lower ones more or less united along their ventral edges (forming the keel or carina) (Fig. 172); this keel encloses the stamens and pistils. In the bud, the keel is enclosed by the wings, and the wings by the standard. Stamens are mostly ten in number, and either all the filaments are united {monadelpJious) , as in Lupinus, or nine are united and one is free (Fig. 188) (diadel- phous), as in clovers and alfalfa, or rarely all stamens are separate (polydelphous), as in Sophora and Thermopsis. Fig. 172. — Flower of Leguminosae. A, floral diagram of Vicia faba; B, sweet pea flower, dissected, diagrammatic. (A after Eichler, B after Bergen and Caldwell.) The united stamens form a tube enclosing the pistil in monadelphous and diadelphous forms. There is a single superior pistil; the ovary is usually one-celled, sometimes two-celled by the intrusion of the sutures, as in some Astraga- lus spp., or occasionally several-celled by cross-partitions; there is one style, and one to many ovules. Fruit. — In nearly all members of the family, the fruit is a legume or pod, that is, a fruit of one carpel which opens along two, both the ventral and dorsal, sutures. The ventral suture of the bean or pea pod, for example, is the one along which the seeds are attached. In one- tribe (Hedysareae) , 4l6 BOTANY OF CROP PLANTS the fruit is a loment, that is, a jointed indehiscent legume, constricted between the seeds. The style, calyx, and withered stamens are often partly persistent in the fruit. Seeds. — The seeds are usually without endosperm; the cotyledons are thick and full of food. The seeds of legumes are noted for their great longevity. Some have been known to retain their viability for 150 to 250 years. This is correlated with their very hard, imper- meable seed coats. So-called "hard seeds" are very com- mon in the pea family. Such seeds are tardy in their ger- mination, either under laboratory or field conditions. As a rule, only a portion of a crop of seeds is hard, although in some cases the whole crop may be hard. It is claimed that a larger percentage of hard seeds is produced in dry climates or when ripening takes place under dry seasonal conditions than in moist climates or moist seasons. The permeability of leguminous seeds can be increased by "scarifying," that is, passing them through a machine that abrases the surfaces. The ordinary alfalfa huller is effective as an abraser, as is shown by the experiments of Harrington who found that alfalfa seed, grown under a variety of soil and chmatic conditions, had about 90 per cent, of hard seeds if hulled by hand and only about 20 per cent, if hulled by machine. Key to Principal Gknera of Leguminos^ Plants with tendril-bearing leaves (Fig. 19). Calyx lobes leafy; stipules large, rounded (Fig. 19), Pisum (pea). Calyx lobes not leafy; stipules mostly small, pointed. Style slender, bearded at the tip (Fig. 173, A;, Vicia (vetch). Style flattened, bearded along the inner side (Fig. 173, B), Lalhyrus (vetchjing). Plants without tendril-bearing leaves. Leaves palmately three-foliate (Fig. 183), Trifolium (clover). Leaves pinnately three-foliate, rarely five- to seven-foliate (Fig. 182). LEGUMINOSvE 417 Flowers small, many in a cluster. Flowers in slender, spike-like racemes, McHlotiis (sweet clover). Flowers in lieads or short spikes, Medicago (alfalfa and other mcdicks). Flowers medium to large, few in a cluster. Pods smooth, mostly large. Keel of corolla spirally coiled (Fig. 176, A), Phaseoliis (bean). Keel of corolla merely incurved, Vigna (cowpea). Pods hairy, small, Soja (soy bean). Leaves pinnate, with two pairs of leaflets, Arachis (peanut). PISUM (Pea) Description.— The plants are herbaceous trailers or climbers with hollow stems. The leaves are pinnately compound, with one to three pairs of leaflets, the terminal one, and in some cases the upper lateral ones, modified as tendrils, which are sensitive and prehensile; the stipules are large and leaf-like (Fig. 19). The inflorescence is a few- flowered axillary raceme. The flowers are either white or pur- plish, diadelphous, and bear a single pistil with the style bearded on the inner side (Fig. 173, A). The pea is capable of self-fertilization although it may sometimes be cross-ferti- lized. The mature fruit is a typical legume with a number of smooth or wrinkled, usually green or yellow seeds C'peas"). Gregory studied the histology of round and wrinkled peas. In round peas, including the indented sugar peas, the central tissue in the cotyledon leaves is filled with very large starch grains. In wrinkled peas, on the other hand, this region of the cotyledons has starch grains which are usually compound, the component parts being about one-half the size of the grains in smooth peas. The seed coat is 27 Fig. 173. — A. style and stigma of Vicia; B, same of Lathryus. 4l8 BOTANY OF CROP PLANTS thin; endosperm is wanting; the stored food is within the two cotyledons. The cotyledons remain underground during germination {hypogean germination), as in all cereals. This type of germination is different from that in the bean and squash, for example, in which the two cotyledons are raised above ground, and for a time are food-making organs. This sort of germination is called epigean. Types of Peas. — There are but two well-recognized types of Pisum: Garden peas and field peas. These are briefly distinguished as follows: Flowers white; seeds globular, uniformly yellowish, white or bluish green; leaf axils green, unpigmented; comparatively tender Pisum sativum (garden pea). Flowers colored, usually purplish, red or lavender; seeds angular, gray- brown, gray-green, gray-yellow or gray speckled with fine spots of various colors; leaf axils pigmented; comparatively hardy Pisum satitum (field pea). Garden Peas.- — The common garden pea can be divided into two groups: Shelling peas, and edible-podded or sugar peas. In the former, the pod is lined on the inside by a thin, hard membrane (endocarp) which at maturity causes it to split open. In the edible-podded or sugar peas, this mem- brane does not become dry and twisted at maturity, and the pods remain soft and tender. Shelling Peas. — Vilmorin classifies the varieties of common shelhng peas into two groups: Round or smooth-seeded, and icrinkled-seeded. Each of these is divided into (i) tall climb- ing, (2) half -dwarf, and (3) dwarf varieties, and each of the latter three groups into white-seeded and green-seeded sorts. The sugar peas occur in both tall, half-dwarf, and dwarf forms. Period of Maturing. — As a general rule, the earliest sorts of peas have smooth, round seeds, while the late sorts have LEGUMINOS^ 419 wrinkled seeds. Smooth-seeded varieties are hardier than wrinkled-seed varieties. This is not invariably the case, however. Furthermore, dwarf and medium-sized forms are early, while tall varieties are late. Green garden peas Fig. 174. — Pea pods showing types and range of variation. A, extra early dwarf wrinkled pea, American Wonder; B, medium early wrinkled pea, Nott's Excelsior; C, main crop smooth pea. Marrowfat. (_After Corbetl.) are sometimes classified as to their time of maturing into early, medium, and late or main crop. First of all, Alaska, and American Wonder are examples of early sorts, McLeans, Advancer, and Pride of Market of medium sorts, while among late-maturing crops are such varieties as Telephone, Telegraph and White Marrow Fat. 420 BOTANY OF CROP PLANTS Field or Canadian Field Peas. — These have smooth, hard, rather angular seeds. They are gray-green, gray-yellowish, or gray dotted with purple, blue, rust red or brownish spots. Garden peas are sometimes used as a field crop. Fig. 1 75. — Pea pods showing types and range cjf variation. D, French can- ning type smooth pea, French Canner; E, large podded wrinkled pea, Pride of Market; F, fleshy or edible podded pea, Melting Sugar. {After Corbell.) Field peas are successfully grown only in those regions with a cool growing season, in fact, they will withstand quite heavy frosts. High temperatures accompanied by high relative humidity are decidedly injurious. Excellent crops are grown at 7,000 to 8,000 feet in the San Luis Valley of Colorado. They do well on most types of soil. LEGUMINOS^. 421 Peas and Mendelism. — Grcgor Mcndd's famous experiments in plant hybridization were carried on with the common garden pea. He discovered certain laws in the behavior of his hybrids, and these are now famed as Mendel's Laws. He selected a number of dififerentiating (paired) characters and observed their behavior when crossed with each other. In the brief summary, here of his work, a number of characters of the genus Pisum are brought out: 1. Round or roundish form of seed is dominant over angular or wrinkled seed. That is, when a plant bearing roundish seeds is crossed with one bear- ing angular or wrinkled seeds, the hybrid offspring bears seeds all of which are roundish. 2. Yellow color of cotj'ledons is dominant over green color of cotyledons. 3. Gray seed coats are dominant over white seed coats. 4. Inflated seed pods are dominant over pods constricted between the seeds. 5. Green color of unripe pods is dominant over yellow color of unripe pods. 6. Distribution of flowers in leaf a.xils is dominant over their distribution on the ends of stems. 7. Tall stem is dominant over short stem. Uses. — Peas in the green state are one of the most common vegetables. They are also canned in large quantities. Field peas are being grown as a companion crop, soiling crop, green manure, and as a food for hogs, sheep, horses and cattle. It is the practice in many places to pasture Hve stock, particularly hogs and sheep, on field peas. PHASEOLUS (Bean) Description. — Representatives of this genus are annual or perennial herbs or vines with pinnately three-foliate, rarely one-foliate, leaves. The flowers occur in axillary racemes; they vary in color: white, yellow, red, or purple. The calyx is five-toothed or live-lobed, the two upper teeth or lobes being either united or free. The standard of the corolla is often recurved or somewhat contorted; the wings equal or exceed the standard, while the keel is cliaracierislicaUy spirally coiled (Fig. 176, A). The stamens are diadelphous (nine and one). The ovary has a stvle longitudinally bearded, and 422 BOTANY OF CROP PLANTS standard numerous ovules. Members of the genus are quite regularly visited by insects. The pod is linear, straight or curved, sub terete or compressed, two-valved, and tipped with a persistent style. The seeds ("beans") are large and have a prominent, approx- imately central hilum, on one side of which is the micropyle, on the other, the raphe. The embryo is large and occupies the whole of the seed, i.e., endosperm is wanting. The hypocotyl and plumule are prominent; the two large cotyledons are slightly concave on their inner faces. The germination of the bean, and the bean seedling, are common objects of study in general botanical courses. Geographical and Species.— Members of the genus Phaseohts are tropical and warm-country plants. According to Britten and Brown, there are close to i8o Fig. 176. — Common (Phaseolus vulgaris). A entire flower. X 2j'2. kidney bean spiral keel; B, species. A number of "beans" do not fall within the genus Pliascohis, for example, broad bean {Vicia faba), soy bean {Soja max), velvet bean (Mucuna utilis), asparagus or dolichos bean {Vigna sesquipedalis), cowpea or bean {Vigna sinensis), Jack bean {Cana- valia ensiformis) , locust bean {Ceratonia siligna) and hyacinth bean, bonavist or lablab {Dolichos lablab). LEGUMINOS^ 423 The adjuki bean {Phaseolits angularis) and mung bean {Phaseoliis aureus) arc now grown to some extent in this country. Key to Principal Species of Phaseolus Roots tuberous or much thickened, P. multiflorus (scarlet runner bean). Roots fibrous. Seeds flat or flat-oval in cross-section, P. lunalus (Sieva and Lima beans). Seeds mostly • circular, but sometimes flat in cross-section, P. vulgaris (kidney bean). PHASEOLUS MULTIFLORUS (Scarlet Runner Bean, Dutch Case- knife Bean, Flowering Bean, or Painted Lady) These are perennials which usually have tall, climbing stems and pinnately trifohate leaves. The large and showy flowers are scarlet (scarlet runner), or white (Dutch case- FiG. 177. — Pistil of flower of common bean (Phaseolus vulgaris). {After Knulh.) knife), and form racemes. Pods are 3 to 6 inches long, and curved; the seeds are large and plump, flattened or cylindric, and vary in color. The scarlet runner form is also known as the flowering bean or painted lady, and is much used as an ornamental vine. The Dutch case-knife form of this species — one with- white 424 BOTANY OF CROP PLANTS flowers — is grown for the edible beans. The Aroostook bush Lima bean is considered by Tracy to be a bush form of Phaseolus muUiflorus. The species is raised to some extent by the Mexicans, and it is very probable that some at least of the so-called "Mexican beans" are varieties of this species. Phaseolus muUiflorus is a native of South America and Mexico. PHASEOLUS LUNATUS (Sieva and Lima Beans) These vary in form from low and bushy to tall and climb- ing. The leaves are pinnately trifoliate, the leaflets varying from narrowly lanceolate to ovate. The flowers are small, and in axillary racemes. The pods are usually broad and flat, and have flattened, variously colored beans. The native home of these beans is tropical South America. They require higher temperatures than the varieties of Phaseolus vulgaris. Classifications of Types of Lima Beans. — There are two general types of Limas, as follows: (i) Phaseolus lunatus, including the Sieva or Carohna type of Lima, and (2) P. lunatus var. macrocarpus, including the true Limas. The latter have a taller and much more robust growth, and thicker leaflets than the Sievas or Carolinas. In both groups above, there are pole and bush forms. Table Showing Relationship of Types of Lima Beans Phaseolus lunalus (Sieva, Civet, or Carolina beans). Plants bush (Henderson's Bush Lima). Plants pole (Small White Lima, Florida Butter). Phaseolus lunalus v&r. macrocarpus (true Limas). Seeds very flat and veiny; pods broad and flat, with tip not prominent leaflets broad, not ovate, Flat-seeded Limas. Plants bush (Burpee's Dwarf Lima). Plants pole (King of the Garden). I.KGUMINOS^ 425 Fig. 179. — Types of Lima beans. A, Potato Lima, pole; B, Sieva type, pole; C, large, flat Lima, dwarf; D, Sieva type, dwarf. {Modified after Corhrll.) 426 BOTANY OF CROP PLANTS Seeds smaller; pods short and thick, with prominent tip; leaflets tapering, long ovate, Potato Limas. . Plants bush (Dreer's Dwarf Lima). Plants pole (Dreer's Improved). PHASEOLUS VULGARIS (Kidney Bean) These are annual plants, with pmnately trifoliate leaves and ovate leaflets. The flowers are small, not over % inch across the wing, and are white, yellowish, or blue-purple. The slender pods vary in shape, and have kidney-shaped seeds. This species is thought to be a native of tropical America. The cultivated varieties thrive best where the growing season is warm. There are, according to Tracy, 145 varieties of kidney beans in America. These are usually divided into two large subdivisions, pole and hush. These in turn each possess green-podded and wax-podded sorts. The bush beans are often grouped together under the variety P. vulgaris nanus. Most of our common garden sorts are dwarf or bush beans. ^ The strLnginess of bean pods is due to strips of inedible, tough fibers at the sutures. Uses of Beans.- — Beans are used in large quantities dried, and in the pod as "green beans." Lima beans are often canned with corn in succotash. Great quantities of common kidney beans are put up in the form of "pork and beans." The Mexicans and southwestern Indians raise beans in large amounts; beans constitute one of their chief articles of diet. VICIA (Vetch, Broad Bean) Generic Description.^ — The Vicias are chmbing or trailing herbaceous vines. The leaves are pinnate, tendril-bearing, ^ For a detailed classification of American varieties of beans see Bull. 109, Bureau of Plant Industry, by W. W. Tracy. LEGUMINOS^ and with half-sagittate or entire stipules. The flowers are blue, violet, yellowish, or white, and in axillary racemes. The calyx tube is oblique, and its teeth or lobes are about equal, or the two upper ones somewhat longer. The standard is notched at the tip, and the wings are attached to the curved keel. The stamens are diadelphous (nine and one), or monadelphous below, and have filiform filaments. The sessile or stipitate ovary has numerous ovules and a slender style with a tuft or ring of hairs at its summit (Fig. 173, A). The pod is flat. Geographical. — There are more than 100 species of Vicia, of wide geograph- ical distribution. There are about 20 wild species in the United States. Key to Important Species of Vicia Plants erect, smooth, or only slightly hairy, seldom tendril-bearing; flowers whitish with dark blue spots on each wing, V.faba (broad or Windsor bean). - Plants weak, usually hairy, tendril- bearing; flowers purplish. Leaves rounded at tip; flowers many, in long one-sided racemes (Fig. 182), V. viUosa (hairy vetch). Leaves truncate at tip; flowers few, usually two in each leaf a.xil, V. saliva (vetch). Fig. 180. — Types of bean seeds. I, Broad Windsor; 2, White Narrow Field; 3, Dutch Case Knife Pole; 4, White Dutch Run- ner Pole; 5, Grenells Stringless Green Pod; 6, Long Yellow Six Weeks; 7, Long White Pole Lima; 8, Powell's Prolific Pole; 9," Dreer's Pole Lima; 10, Florida Butter Pole Lima; 11, Yellow Cranberry Bush; 12, Horticultural Wax; 13, Red Mexican; 14, French Kidney. {Modified after Tracy, U. S. Dept. Agri.) 428 BOTANY OF CROP PLANTS Less Common Species. — There are a number of other Vicia spp. that are cultivated to some extent, as follows: Narrow-leaved vclch {Vicia anguslifolia) is a native of the eastern United States, and is grown somewhat in Georgia Fig. i8i. — Broad or Windsor bean (Vicia faba). as a hay crop. Black bitter vetch {Vicia crvilia) is an Asiatic species, cultivated somewhat as a winter green-manure crop in California. Purple vetch {Vicia atropurpurea) resembles hairy vetch from which it differs, however, in being smooth. It is cultivated on the Pacific Coast and in the South. Scarlet LEGUMINOS.« 42Q velch {Vicia fulgcns), Narhonnc vclch {Vicia narbonnemis) and woolly podded vetch {Vicia dasycarpa) arc rather rare species, cultivated to a slight degree on the Pacific Coast. The term "vetch'' is given to a number of plants, not belonging to the genus Vicia, for example: Crown vetch {CoroniUa sp.), kidney vetch (Antliyl- lis vulncraria), Dakota vetch {Ilosackia amcricana) and Lalhynis spp. VICIA FABA (Broad Bean, Windsor Bean) This is a strong, erect annual, 2 to 4 feet high with a well- developed primary root (Fig. 181). The leaves are pinnately compound, and become blackish on drying. The inflorescence is an axillary raceme of two to six flowers. The flower is white, its wings marked by a large black spot. The pods are large and thick, and vary considerably in length, each bearing a number of large, black seeds. The smaller-seeded sorts, sometimes known as pigeon bean, field bean and tick bean, are used as an animal food, while the large-seeded varieties are used as human food. The home of the wild plant from which the cultivated varieties are derived is Algeria. Broad bean is cultivated chiefly in Canada. It thrives best where the summers are long and cool. VICIA SATIVA (Common Vetch or Tares) This is an annual climbing plant which branches freely. The leaves are pinnately compound with about seven pairs of leaflets, and a terminal tendril. Flowers occur singly or in twos in the leaf axils; they are short peduncled, and reddish purple (rarely white) in color. The flowers are cross-fer- tilized. The hairy pods have four or five smooth, globular, gray or marbled seeds. The Willamette Valley, Oregon, produces a large proportion of the common vetch seed in the United States. Vetch seed loses its viability very rapidly after about the third year. The plant is a native of Europe. 430 BOTANY OF CROP PLANTS It has become naturalized in many parts of the United States, occurring in fields and waste places. Common vetch is sown either as a winter or spring annual. If the winters are severe it is planted in the spring. This is the practice in the Northern States. However, in the south, where the winters are mild, it is planted in the fall. It is adapted to a light soil. It is intolerant of a poorly drained soil. The poorer soils of the East, deficient in lime, will support a fair crop. There are numerous varieties of the common vetch. Spring and winter varieties are recognized. The white or pearl vetch has white flowers and seeds. Uses.^ — Common vetch is grown in the old country, and to an increasing extent in United States, as a hay crop. When grown for this purpose it should be cut when in bloom. The seeds are sometimes made into a flour. The species is also being recommended as a cover crop for orchards, and as a green manure. VICIA VTLLOSA (Hairy, Hungarian, Russian, Siberian, or Villous Vetch) Hairy vetch (Fig. 182) is an annual or biennial, hairy plant naturally suited to cool temperate regions. The plants may grow to a length of 12 feet or more, but seldom to any consid- erable height on account of the weak stems. There is an ex- tensive and deep root system which in the early stages of growth, particularly, constitutes a large proportion of the total weight of the plant. There are five to eight pairs of leaflets, and many (about thirty) violet-blue, rarely white, flowers in one-sided racemes. Cross-fertilization is necessary for the normal production of seeds. Bees are chief agents in the dissemination of pollen. The pods are smooth, pale in color, and contain. two to eight small, globular black seeds. The cotyledons remain underground at germination, as is the case in the common garden and field pea. Hairy vetch is a LEGUMINOS^ 431 native of Europe and Asia. It is much hardier than common vetch, and consequently can be grown at ;higher latitudes. Moreover, it is more drought-resistant and tolerant of alkali. \/r ^ % f "^^V. ti ^ ^•^Sr ^ Fig. 182. — Hairy vetch (Vicia villosa). Hot summer weather is very harmful to its growth. It is frequently planted on light, sandy soils, where it may be plowed under as a green manure. 432 BOTANY OF CROP PLANTS The plant has a variety of uses: hay, 'pasturage, cover crop, silage, and green manure. It is usually cut for hay about the time the first pods are full grown. The quality of the hay decreases after this period. LATHYRUS (Vetching, WUd Pea) This genus resembles Vicia. The leaflets are broader, as a rule, however, the flowers are larger, and the stigma is hairy along the inner side (Fig. 173, B). There are over 100 species of Lathyrus, natives of the Northern Hemisphere and of South America. There are numerous wild sorts in the United States. The two most common species are Lathyrus odoratus, the common sweet pea, and Lathyrus latifolius, the everlasting or perennial pea. Lathyrus odoratus is an annual, bearing two to four flowers on a peduncle, and pods 4 to 5 inches long. The following Lathyrus species are of forage value and are now planted to some extent in this country: L. tingitanus (Tangier pea), L. cicera (flat-podded pea) and /,. ochrus (ochrus). TRIFOLIUM (Clover) Generic Description. — Representatives of this group are annual (crimson clover) or perennial (white clover) herbs with palmately trifoliate (hence the name, TrifoUum) leaves (Fig. 183), the stipules of which are adnate to the petiole. The inflorescence is a dense spike or head. The flowers vary in color. The calyx is persistent, its teeth nearly equal, and usually bristle-form. The corolla is also persist- ent, sometimes grown fast to the tube of filaments. The stamens are diadelphous (nine and one). The ovary is sessile or stipitate, and few-ovuled. The pods are small, mem- branaceous, mostly one-seeded (rarely more), indehiscent or opening circularly. The seeds are. small and kidney-shaped. LiccuMiNos.*: 433 Geographical. -There arc close to ^oo species of Trijolium, most of which occur in the north temperate regions; a few, however, also occur In South America and South Africa. They are distributed from low to high altitudes. Besides those given in the following key, two others, T. suaveolens (Shaftal or Persian clover) and T. alcxandrinum (Hcrscem) are grown to some extent in the United States. Key to Principal Species of Trifolium Flowers in spike-like heads, much longer than thick, T. incarnatum (crimson or scarlet clover). Flowers in globular or ovoid heads. Corolla white or yellowish- white, sometimes touched with pink; stems creeping, T. repens (white clover). Corolla red, red-purple, or rose-colored; stems erect or nearly so. Flowers pedicelled; stipules acuminate (Fig. 183, A), T. hyhridiim (Alsike or Swedish clover). Flowers sessile; stipules abruptly acute (Fig 183, D). Blade of leaflet marked with large spot; heads sessile, T. pratense (red clover). Blade of leaflet without spot; heads stalked, T. medium (mammoth or zigzag clover). TRIFOLroM REPENS (White or Dutch clover) Description. — This is a low, smooth, perennial herb aris- ing from a straight tap root. The root system is shallow. The plant possesses creeping stems which develop adventi- tious roots at the nodes. The long-petioled, trifoliate leaves have inversely heart-shaped or notched leaflets and narrow, membranous stipules. The inflorescence is a head and is borne on a long flower stalk which arises in the leaf axils. The flowers are small, fragrant, and white or pinkish. They are erect at first, but become deflexed when mature. The visitation of insects is necessary for the production of a good crop of seed. The small pods are usually four-seeded. The seeds vary a great deal in their longevity. Germination of so-called "hard seeds" may be delayed several years in the soil. Such seeds usually show up in germination tests. 28 434 BOTANY OF CROP PLANTS Geographical, and Uses. — White clover has become dis- tributed throughout the greater part of temperate North America, Europe, and Asia. It is common in lawns, pas- tures, and meadows, and is an important ingredient of lawn grass mixtures. The only distinct agricultural variety is Ladino clover {Trifolium repens latum). It is larger than ordinary white clover, and less resistant to cold. Environmental Relations. — White clover will withstand greater temperature extremes than either red clover or alsike clover. It is naturally suited to cool, moist regions. It is more tolerant of shade than red and alsike clovers. TRIFOLIUM HYBRIDUM (Alsike, Alsatian, or Swedish clover) Description. — Alsike is an erect, branching, rather stout, almost glabrous perennial, i to 3 feet tall. Its life period is from four to six years. There are many secondary roots which soon become as large as the main tap root. The leaves are long and have greenish veins, long taper-pointed stipules (Fig. 183, A), and obovate leaflets. The plant is more leafy than red clover. The plant is usually cut for hay when in full bloom. The flowering heads are on long peduncles which arise from leaf axils. The flowers are pedicelled, and white or pinkish. The pods are two- to four-seeded. The seeds lose their viability rapidly after the second year. Geographical, and Uses.- — Alsike clover is a native of Europe. It has been introduced into this country for agri- cultural purposes and has escaped from cultivation, often being found in fields and waste places. It is not a hybrid between white clover and red clover, as formerly thought. The plant is grown in the same manner and for the same purposes as red clover. The plant is very hardy, more so than red clover, and is quite frequently mixed with timothy LEGUMINOS^ 435 for planting at high altitudes and latitudes. It is prized as a honey plant. TRIFOLIUM INCARNATUM (Crimson, Scarlet, or ItaUan Clover) Description. — This is an erect, soft-hairy annual, 6 to 36 inches high. The leaves are long petioled; the stipules are broad and with dark purple margins; the leaflets are Fig. 183. — A, stipules of alsike clover (Trifolium hybridum); B, leaf of yellow sweet clover ( Melilotus alba) ; C, leaf of crimson clover (T. incarnatum) ; D, leaf of common red clover (T. pratense); E, leaf of alfalfa (Medicago sativa). almost sessile, and obovate or obcordate. The inflorescence is a terminal, dense, elongated, spike-hke head (Fig. 184). The flowers are bright crimson (rarely white, yellow, rose or variegated) and showy. The seed is shiny when fresh'and pinkish in color. 436 BOTANY OF CROP PLy\NTS Geographical, and Uses.— Crimson clover is a native of Europe. It has become naturalized in the eastern portions of the United States, where it occurs quite commonly in waste places. The plant is grown in this country mainly as a crop for hay, forage, or silage. It also has some value as a soiling crop and as a cover crop. The hay sometimes proves dangerous to horses, due to the tendency of the hairy calyces to form indigestible masses in the stomach of the animal, especially if the plants are too ripe when cut. These hair balls seldom form in the stomachs of cattle and sheep. Environmental Relations. — Crimson clover is less resistant to low temperatures than any of the other common clovers. It is grown with success in orchards, because of its shade tolerance. Although it prefers sandy soil, it will do well in soils of heavier type. TRIFOLIUM PRATENSE (Common Red or Purple Clover) Habit, Stems and Roots.^ — This is a perennial plant, more or less hairy, branching, decumbent or erect, 6 to 24 inches tall, rising from the crown. The life period is a varietal character. The average is about three years. It develops from a strong tap root which possesses an extensive system of laterals. The tap root reaches a depth of 3 or 6 feet. It draws moisture and mineral nutrients from the lower soil layers. In general there is about i pound of root to 2 pounds of plant above ground. This means that the clover crop leaves considerable organic matter in the soil. Leaves.- — The leaves are of the clover type, with hairy- margined leaflets and large conspicuously purple-veined stipules. The leaflets often bear a pale spot in the center. Inflorescence and Flowers.- — The terminal inflorescences are ovate (Fig. 184). Each inflorescence has from 35 to 150 purple-rose flowers. The second crop usually has more flowers It LEGUMINOS.T. 437 per head than the first croj). The flowers are of the ordinary pea type, except that the petals are united at their bases and to the staminal tube to form a corolla-tube about ^2 inch long. Fig. 184. — Crimson clover (Trifolium incarnatum), on left; common red clover (T. pratense), on right. Fruit. — The ovary develops into a capsule, bearing one seed. There are two ovules in each ovary, but only one, as a rule, matures into a seed. Infertile ovules are quite com- 438 BOTANY OF CROP PLANTS mon in red clover, the larger percentage usually being in the first crop. This is probably one of the chief reasons why the second crop of clover is more commonly used for seed. An additional advantage in harvesting the second crop for seed rather than the first is that the farmer is able to get two crops in a season, for if the first crop is allowed to seed, there is insufficient food supply, and in some instances a season too short, for the development of a vigorous second growth. In addition to the reason given above for the relatively light yield of seed in the first crop, it is claimed that pollinating insects are not abundant enough, and that the plant is occu- pied with the production of new shoots rather than reproductive activity. In general, a rank-growing plant is not a good seed producer. Fig. 185— When the capsule is mature, the stylar end Fruit of red '^ ^ f clover (Trifo- separates from the basal part by an irregular m^Th'enfa^ged. transvcrse line. The upper part of the cap- sule, together with the style, comes off as a fid (Fig. 185), and the single seed escapes. The seeds are kidney-shaped, and yellow, or mixed yellow and violet in color. Pollination.- — Red clover flowers are protandrous. The work of Westgate and Coe establishes the fact that "red clover flowers must be cross-pollinated in order to set seed on a commercial basis." The pollen must come from a separate plant, for even when taken from flowers of the same plant, the percentage of seed set is very small. The bumble- bee {Bombus) is the most important insect visitor of the red clover. It is capable of pollinating 30 to 35 flowers a minute. Honey bees are also efficient polhnators. When the bumble- bee fights on the clover head and inserts its proboscis into the staminal tube, its weight presses down on the keel and LEGUMINOSiE 439 wings of the flower, from which nectar is being taken, thus forcing out the stigma and anthers up against the bee's head. The stigma becomes dusted with pollen from another flower and the anthers open, leaving pollen on the under side of the bee's head. The flower parts return to their original position when the bee leaves the flower. Nectar sought by the bee is secreted at the bases of the stamens, and collects in the staminal tube. Geographical. — The species is a native of Eurasia. It has become natural- ized in the United States, occurring commonly in the fields and meadows throughout most of our area. Environmental Relations.— Red clover attains its best growth in humid sections of the country, and where the summer and winter temperatures are not extreme. Un- like alfalfa, dry atmospheric conditions are detrimental to red clover; but hke alfalfa it requires lime in the soil. More- over, it is intolerant of a poorly drained soil and of much shade. Mammoth Clover. — This clover, sometimes known as perennial clover, sapling clover, pea-vine clover, and bull clover, is a form of the ordiTiary Trijolium pratense; as compared with the latter, mammoth clover matures later, has a more highly branching tap root, longer pedicels, and solid stems. It is known as Trijolium pratense perenne. Uses. — Common red clover is one of our most prized forage and hay crops; it is also raised to some extent as a green-manure and cover crop. Its importance as a crop in the United States may be judged from the fact that the total acreage is about five times that of alfalfa. It is adapted to the, humid sections of the country. The highest percentage of digestible substances occurs in the plant just before full bloom. The plant soon becomes tough and fibrous after the blooming period. 440 BOTANY OF CROP PLANTS Fig. i86. — A vigorous alfalfa plant showing the "crown" from which arise the numerous shoots. {After Headden, Colo. Agr. Exp. Sta.) LEGUMINOS.E 441 TRIFOLIUM MEDIUM (Zigzag, Medium Red, White, Mammoth or Meadow Clover) This is a perennial clover resembling red clover [T. pra- Icnse), described above. The plant is larger, however, its stems are more spreading and bent more zigzag at the nodes; the leaflets are longer and narrower, and the stipules longer and more pointed. The leaflets are lanceolate or oblong and not spotted as in the red clover. The flowers are bright purple. This species is a native of Siberia and possibly Europe. It has gained entrance into this countr}- and occurs here and there in the eastern United States as a ruderal. A\(¥" The plant is being grown in the same manner and for the same pur- pose as common red clover. MEDICAGO (Medics) Generic Description.- — The medi- cagos are mostly herbs, sometimes woody at the base, as in common (fV^^^^^ alfalfa, and very rarely shrubby (one — ^^ species in southern Europe). The leaves (Fig. 183, E) are pinnately three-foUate, the stipules adnate to the petiole, and the leaflets com- monly dentate, pinnately veined, with the veins terminating in the teeth. The flowers are small, yellow or violet, in axillary heads or racemes. The calyx teeth are short, and about equal in length. The petals are free from the staminal tube; the standard is obovate or oblong, the wings oblong, and the keel short and obtuse. The stamens are diadelphous (nine and one). The Fig. 187. — Seed and pod of alfalfa (Medicago sativa). X .=5- 442 BOTANY OF CROP PLANTS ovary is sessile or short-stipitate, and several- or rarely one- ovuled; it has a subulate (awl-shaped), and smooth style. The pods (Fig. 187) are curved or spirally twisted, veiny or spiny, and indehiscent. Geographical. — There are a number of species of Medi- cago, all of which are native to the eastern hemisphere. They naturally range from Eastern Asia to Southern Africa. There are seven perennial species of Medicago, and about 37 annual species, one of which, yellow trefoil {Medicago lupu- lina), has a biennial or possibly perennial form. The non- perennial species are commonly known as "bur clovers." They will grow naturally as winter annuals. Key to Principal Species of Medicago Perennial, erect-growing plants; flowers violet, Medicago saliva (alfalfa). Annual, low-growing plants; flowers yellow. Pods kidney-shaped, without spines, Medicago lupulina (hop clover). Pods cylindrical, with spines. Stems pubescent; pods 3^^^ to 5 millimeters diameter; purple spot in center of each leaflet; two to eight seeds in each pod, Medicago arabica (spotted bur clover). Stems glabrous, pods 7 to 10 millimeters diameter; no purple spot in center of each leaflet; three to five seeds in each pod, Medicago hispida (toothed bur clover). MEDICAGO SATIVA (Alfalfa, Lucerne) Roots. — Alfalfa is a deep feeder. The young plant usually sends down a single tap root. As a rule, this takes a straight downward course. Comparatively few side roots are given off. Usually, these are below the depth of 4 feet. Headden found in a plant only nine months old, that the young roots had extended to a depth of over 9 feet. Ordinarily the weight of roots exceeds weight of top. Stems.- — Alfalfa is an ascending or erect perennial. Its life period is dependent upon environmental conditions^and LEGUMINOS^ 443 the variety. The average life is from five to seven years. Fields 20 to 25 years old are found in the semi-arid sections. At or near the ground level, is a short, compact stem (crown) from which the numerous (20 to 50) branches arise (Fig. 186). Blinn has shown that there is a well-defined relationship be- tween the nature of the crown and hardiness. Non-hardy types of alfalfa have an upright-growing crown with but few buds and shoots developed below the soil surface. The crown of hardy types is more spreading and the numerous buds and shoots come from below the soil surface. Hence in the latter case, the buds and young shoots are protected by the soil from winter freezing. These hardy types are Grimm and Baltic strains. The stems of alfalfa are rather slender and freely branching. Common alfalfa has no rootstocks. Some forms of Medicago falcata possess them, however, and they also occasionally appear in some variegated types. "Cuttings" of Alfalfa.— The number of "cuttings" of alfalfa depends upon the length of the growing season, and the water supply. Three cuttings are usually made through- out most of the alfalfa-growing regions of the United States. In the Imperial Valley, California, ordinary alfalfa has yielded as many as nine cuttings in a year. This practice indicates that alfalfa has the capacity of sending up numerous shoots from the crown. The shoots of a second or third crop begin to appear about the time the plant is coming into bloom, and it is the usual practice to cut the crop at this time, so that the food supply that would normally go into developing fruit and seed, is diverted to the young growing shoots of the succeeding crop. Furthermore, the leaves are richest in nutritive substances when the plant is in bloom. The leaves contain about 80 per cent, of the protein in the plant, hence methods of harvesting should look toward the prevention of their loss. The different cuttings of alfalfa 444 BOTANY OF CROP PLANTS vary somewhat in quality and chemical composition. How- ever, more data are needed to determine the relative feeding value of the different cuttings. The alfalfa plant is a heavy feeder. According to Ames and Boltz, a 3-ton yield of alfalfa hay contains 163 pounds of nitrogen, 17 pounds of phosphorus, 99 pounds of potassium, and 90 pounds of calcium. Leaves. — The alternately arranged leaves are trifoliate (Fig. 183, E). They are oblong in general outline and sharply toothed along the margin; the tip is terminated by a pro- jecting midrib. The stipules are prominent. Inflorescense. — This is a dense raceme springing from the axils of the branches. Flowers. — The ordinary color of the flower is purple or violet, but in variegated types, may be blue, green, or yellow. The calyx teeth are longer than the tube of the calyx. The standard is somewhat longer than the wings, which in turn surpass the keel. The staminal tube is held in a state of tension by two opposite lateral projections on the inside of the keel (Fig. 188). Pollination (Fig. 188). — Alfalfa possesses a mechanism for the explosive dispersal of its pollen. When the edges of the keel are spread apart, the staminal tube is released, and both the pistil and stamens snap up against the standard. The pollen is scattered in this process. The process is called ^'■tripping.''' Alfalfa flowers are usually tripped by visiting insects, chiefly bumblebees and leaf-cutting bees [Mega- chile). The weight of an insect may be sufficient to cause a separation of the keel edges, and consequently "tripping." Usually, however, the separation is brought about by the protrusion of the insect's proboscis between the edges of the keel. It has been observed that alfalfa flowers may be tripped without the visitation of insects. This is_termed LKGUMINOS.IC 445 "automatic" tripping. Humidity and tomi)eratuR' condi- tions are probable causative factors in automatic tripping. Both self- and cross-pollination are effective in alfalfa. untnpped \a\eral ^ jtaminal tube- free 5\armr\ untnpp Fig. 1 88. — Pollination of alfalfa. .4, flower untripped with calyx and standard removed; B. same tripped; C. position of staminal tube untripped and tripped. {Ajler U. S. Depi. Agri.) Self-pollination usually results from automatic tripping. It is known that good seed crops are produced in regions where tripping insects are scarce. However, the number 446 BOTANY OF CROP PLANTS of pods set and the number of seeds per pod are increased if cross-pollination (xenogamy) is accomplished. Factors Affecting Seed Production. — As has been indi- cated, cross-pollination results in a greater crop of seed than self-pollination. An abundance of tripping insects may increase considerably the seed output; however, good seed crops occur in regions where tripping insects are scarce. Seed production is usually light in humid sections of the country. Moreover, too much irrigation water apphed during the flowering period is detrimental to seed production. The heaviest yields of alfalfa seed occur in the arid sections of Kansas, Colorado, Utah and Idaho. Isolated plants invariably produce a greater crop of seed than those in a thick stand. The sun's heat favors automatic tripping. Martin finds that the setting of seed pods in alfalfa is largely dependent upon the proper functioning of the pollen. The pollen grains require a certain amount of water to germi- nate. When a pollen grain comes to the stigma, the amount of water it finds there depends upon the moisture delivery of the stigma and the moisture of the air. The supply of water for germination of the pollen grains may be changed by increasing the water in the soil, or the atmospheric humidity about the plant. Fruit. — This is an indehiscent legume, coiled two or three times (Fig. 187). There are one to eight seeds in each pod; they are kidney-shaped, and about 3-^ inch long. The seeds retain their viability for many years. Germination and Seedling.^ — The young seedling consists of two short cotyledons, a hypocotyl, and a tap root. The first foliage leaf is simple, while the second, third, and all others are trifoliate. There is soon formed an erect stem with but few branches; hence the first growth looks thin. However, there spring up later numerous branches from LEGUMTNOS^ 447 the lowermost nodes and from the axils of the cotyledons. The result is a well-developed "crown." Geographical. — Common alfalfa is a native of temperate western Asia. The original home is probably from northern India to the Mediterranean region. It is now being cultivated in many parts of the world, and wherever so culti- vated, frequently escapes and becomes a ruderal. Types of Alfalfa. — Medicago saliva is now quite generally considered to be an heterogeneous species, made up of many strains, varieties, and even subspecies. Westgate holds that some of our hardy strains of alfalfa (Grimm, for example) owe their hardiness to the possession of a small percentage of the ''blood" of the hardy yellow-flowered or sickle alfalfa {Medicago f ale a ta). Numerous forms of alfalfa arise where ordinary alfalfa (M. saliva) and yellow-flowered alfalfa {M. faleata) grow together. These hybrid forms are, of course, unstable. They have been recrossed several times with ordinary alfalfa and also among themselves. Such forms have been termed "variegated alfalfas." Sand lucerne (Medieago media) is considered by some botanists to be a natural hybrid between M. saliva and M. falcala; others consider it to be a distinct species. Sand lucerne has flowers ranging from bluish and purple to yellow, with numerous intermediate shades. The seeds are not as heavy as those of common alfalfa. The plant is a hardy type. Grimm alfalfa, as has been indicated, is quite certainly a form with hybrid characteristics, the parents being common alfalfa and yellow-flowered alfalfa. Other well-known types of alfalfa are: Turkestan, German, American, Arabian, and Peruvian. Turkestan was secured from Russian Turkestan in 1898. The water requirement of the plant is low, and it also pos- sesses an ability to withstand extremes of temperature. The plant is ordinarily a Uttle smaller, and the leaves are narrower and more hairy, than other common sorts. German 448 BOTANY or CROP PLANTS alfalfa resembles Turkestan. It is less hardy, however, and is a poorer yielder than the American type. The latter is the most common western alfalfa. Arabian alfalfas are not resistant to cold, hence they are restricted to the warmer States, particularly Arizona, New Mexico, Texas, and California. Peruvian alfalfa is a productive sort adapted to growth under irrigation in the southwest, where the winters are mild. Brand proposes to place Peruvian alfalfa as a distinct variety (Medicago saliva var. polia). It is taller, less branched, and more rapid in its growth and recovery after planting than common cultivated alfalfas. Further- more the flowers are slightly longer, and the floral bract is longer than either calyx teeth or calyx tube. Environmental Relations.- — Alfalfa is able to withstand high temperatures if the air is dry, but high temperatures accompanied by a humid air are decidedly injurious. For this reason, it is particulary well adapted to the semi-arid sections of the United States, where it is grown both on irri- gated and non-irrigated land. Its resistance to low temper- atures is a varietal characteristic, and also somewhat dependent upon cultural operations. Grimm and Baltic types are less liable to suffer from winter 'killing than the so-called common alfalfas. The following data shows the water requirement of alfalfas, in comparison with other crops (from Briggs and Shantz). Crop Water Requirement Millets 310 Sorghums 322 Corns 368 Wheats 513 Oats 597 Potatoes 636 Alfalfa, Peruvian S. P. I., (30,203) 651 [ Alfalfa, Grimm S. P. I. (25,695) 963 i i LEGUMIN0SJ5 449 In spite of its relatively high water requirement, alfalfa is able to withstand drought. This is due to its deep root system which draws upon the water in the lower strata of soil. Alfalfa cannot withstand alkali, and suffers if soil drainage is not good. The plant requires lime in the soil. The soil type has considerable influence upon the form of the root system. A hard compact soil causes a more or less branch- ing root system, while in a loose soil the tap root system is typically developed. Uses and Production. — Alfalfa is the most important hay crop in the Western States. The total number of acres in alfalfa in the United States, 1909, was 4,707,146; of this number, the Western States furnished 4,523,513 acres. The five leading States, 1909, named in the order of their alfalfa production were Kansas, Nebraska, Colorado, Cal. fornia and Idaho. MEDICAGO LUPULINA (Hop Clover, Black Medic, Yellow TrefoU) This plant is usually annual, sometimes perennial. The stems are four-angled, pubescent, and branched at the base, the branches being decumbent and spreading. The petioled leaves have small obovate, oval or orbicular, denticulate or crenulate leaflets. The flowers are small, yellow, in dense, oblong or cylindrical heads. The pods are black, curved, strongly veined, and one-seeded. The plant is a native of Eurasia. It is now found through- out the greater part of the United States and other temperate regions where it occurs in fields and waste places. It is sometimes planted on poor soil, and has some promise as a green manure. MEDICAGO ARABICA (Spotted Bur Clover) This is a smooth annual plant with procumbent stems. The leaflets have a dark purple spot in the center. The pods 29 4SO BOTANY OF CROP PLANTS Fig. 189. — Pods of 10 species of Medicago. Top row, M. arabica and M. hispida denticulata; second row, M. hispida confinis and M. hispida tere- bellum; third row, M. muricata and M. hispida nigra; fourth row, M. ciliaris and M. echinus; bottom row, M. scutellata and M. orbicularis. {After McKee and Richer, U. S. Dept. of Agr.) LEGUMINOS^ 451 (Fig. 189) arc in long clusters, twisted into three to five spirals, and the edges l)ear numerous groo\c(l spijies which interlock. The seeds are kidney-shaped, and about 2}^ milli- meters long. Medicago arabica inermis is a spineless-podded form . Fu.. 190. — Toothed bur clover (Medicago hispida). Spotted bur clover is a native of Europe and Western Asia. It is introduced into the United States and occurs on the Atlantic, Gulf, and California coasts. It is being used as a pasturage crop. 452 BOTANY OF CROP PLANTS MEDICAGO HISPIDA (Toothed Btir Clover) Toothed bur clover (Fig. 190) is a smooth, annual plant with decumbent leaves. The leaflets often have small whitish and dark red spots scattered over the surface, which disap- pear with age. Th.Q flowers are yellow. The pods are netted- veined, twisted spirally, and spiny. The seeds are light- to brownish-yellow, kidney-shaped, and about 3 milHmeters long. Medicago hispida reticulata and M. hispida confinis are forms with spineless pods. Toothed bur clover, Medi- cago hispida denticulata, is native to the northern Mediter- ranean region. It is the most common bur clover grown in California. It finds some use as a pasture, hay, cover and green-manure crop. In addition to the two species of bur clover given above, there are about 35 species that are not cultivated to any extent. They are all native to the Mediterranean region. All are warm-climate crops. MELILOTUS (Sweet Clover) Generic Description.- — Sweet clovers are tall, erect, annual or biennial herbs, with a fragrant odor, especially when bruised. The leaves (Fig. 183, B) are pinnately three-foKate, petioled, and possess large stipules and dentate leaflets, the veins of which end in the teeth. The flowers are long, slender, and in one-sided, axillary racemes. They are small, and white or yellow. The calyx teeth are short and about equal. The standard is obovate or oblong, the wings oblong, and the keel short and obtuse. The stamens are diadelphous (nine and one). The sessile or stalked ovary bears a single thread-Hke style. The pods are ovoid or globose, small, indehiscent or finally 2-valved, and usually one-seeded. Ordinarily, all the seeds of one year's production do not LEGUMINOSiE 4 S3 germinate the first season. This results from the production of some "hard seeds." There are 15 to 20 species of sweet clover, natives of Europe, Africa, and Asia. They are known by different names, such as wild alfalfa, melilot, giant clover, Bokhara, and sweet clover. Fig. 191. — Leaves mid inliorcseenee of white sweet eluver ( Melilntus alba) on left, and ait'alfa (Medicago sativa) on right. The young plants resemble alfalfa, from which they can be distinguished by the bitter taste of the foliage and the thicker leaflets. Species of Melilotus.— There are two common species of Melilokis: M. alba, white sweet clover, and M . officinalis, 454 BOTANY OF CROP PLANTS yellow sweet clover. Several other species of Melilotus have been used agriculturally to some extent; among such are M. indica ("sour clover"), M. altissima, M. gracilis, and M. speciosa. The characters of the two most important species are arranged in parallel rows for purposes of comparison. M. alba M. officinalis Commonly biennial. Commonly annual, sometimes bien- Flowers white. nial. Standard slightly longer than wings. Flowers yellow. Pods ovoid, glabrous. Standard about equal the wings. Pods ovoid, often slightly pubescent. MELILOTUS ALBA (White Sweet Clover) Description. — This is an erect and smooth-stemed bien- nial. It may reach a height of 3 or 4 feet the first season, from seed; the second season's growth is much more vigorous, and will yield two crops in the Northern, and three in the Southern States. New sprouts arise from above ground near the base of the plant after each cutting, and for this reason the plants must not be cut too close to the ground hne. The leaves have thick, oblong, finely toothed leaflets which are narrowed at the base, and truncate, notched or rounded at the apex. The racemes are numerous, slender, and often one-sided. The flowers are white and have a standard which is somewhat longer than the wings. The pods are ovoid, slightly reticulated (netted), and smooth. The species is a native of Eurasia. It is a common road- side and waste-place weed throughout this country. MELILOTUS OFFICINALIS (Yellow Sweet Clover) Description. — This plant is much like the preceding. It does not grow so tall, however, is less common, and has LEGUMINOS^ 455 yellow flowers. It blooms somewhat earlier than the white sweet clover and is more commonly annual in its habit than biennial. It is a native of Eurasia and, Hke the preceding species, has become naturalized in this country, being widely distributed as a ruderal throughout both the Northern and Southern States. Environmental Relations. — The sweet clovers thrive in both semi-arid and humid climates, and upon all types of soils — heavy and light, rich and poor, well-drained and illy- drained. They are also drought-resistant. It is being intro- duced where, for any reason, alfalfa and clover have failed. Uses of Sweet Clovers. — Like other legumes, sweet clover supports nodules of bacteria on its roots. In fact, it is nearly as valuable as alfalfa to plow under as a green manure to renew the soil. It makes good hay when properly handled, and for pasturage purposes it has considerable value. As a forage crop, it can be utilized where alfalfa or red clover cannot be grown successfully. The plant becomes coarse and unpalatable soon after blooming, and hence it must be cut before this stage. The plants possess a bitter principle, cumarin, which may cause an animal to reject them as food at first, but usually the animal becomes accustomed to them. White sweet clover is much larger and more vigorous than yellow, and consequently is the one recommended for cultivation. SOJA (Soy Bean) Generic Description. — The soy beans are prostrate or erect herbs with pinnately three-, rarely five- or seven-, foliate leaves. The flowers are in short axillary racemes, and are purple or whitish. The pods are linear or falcate, and two- valved. The seeds are globular and pea-like. 456 BOTANY OF CROP PLANTS There are between 15 and 20 species of Soja, natives of tropical Asia, Africa, and Australia. There is only one species of any economic importance. This is Soja max. SOJA MAX (Soy Bean, Soja Bean, Coffee Bean) Description.^ — This is an erect, bushy appearing, hairy annual, varying from 1 1/^ to 6 feet in height (Fig. 192). Unlike the cowpea, it has a definite growth, that is, reaches a cer- tain size and matures its seed. All the pods of the soy bean mature at one time. In the cowpea, new pods are formed as long as the plant lives. The tap root is short B,nd strong. The leaves are tri- fohate. Usually they have withered and fallen by the time the pods are mature, but in some varieties remain green and stay on the plant for sometime after the pods mature. The flowers are borne in axillary clusters; they are small, and either white or purple in color. The flowers are self -pollinated as a rule, and are completely self-fertile. Occasional cross- fertilization occurs in the field when varieties are planted very close together. The pods are from i to 23^^ inches long, yellowish or brown, and covered with short bristly hairs. As many as 300 to 400 pods have been found on one plant, and each pod usually contains two or three seeds. In fact, the soy bean is the greatest seed producer of any legume grown in temperate Fig. 192. —Soy bean (Soja max). {After Piper.) LEGUMINOS^ 457 climates. The seeds vary greatly in color; there are shades of cream, white, yellow, green, brown, and black; they also vary in shape from globose to elliptical. Under the most favorable conditions, soy bean seeds do not retain their viabihty for more than five or six years. Soja max is a native of China and Japan. The cultivated varieties are adapted to the warmer sections of the United States; they are intolerant of cool nights. However, there are several very early maturing varieties which may be grown in the northern tier of States. The soy bean will grow in moist climates, and also manifests drought-resistant pro- pensities. The plant is grown on a variety of soil types, and will even produce a fair crop on poor soils of a sandy nature. Uses. — The soy bean is the most important legume in Asiatic countries, and is becoming of increasing value in the United States. The chief product of the bean is the oil which is expressed from the seeds. It is used in the manu- facture of soaps, lubricants, water-proof goods, linoleum, rubber substitutes and printing ink; also in the preparation of varnishes and paints, as a substitute for linseed oil. After the oil is expressed from the seed, the "cake," either un- ground or ground into a meal, is used as stock feed or as a fertilizer. Soy-bean meal is of considerable value as human food. Soy-bean flour is an important constituent in many food specialties such as diabetic breads, crackers and bis- cuits. Soy-bean flour is very low in carbohydrates, that made from soy-bean cake having a carbohydrate content of 33.85 per cent.,^ as compared with 75.35 per cent, in wheat flour. The protein content of flour made from soy- bean cake is given as 47.3 per cent., whereas that of wheat flour is but 11 per cent. Soy beans are also utiKzed to make a so-called soy-bean milk, w^hich is valued for cooking * Data from the U, S. Dept. of Agri. Bureau of Chemistry. 458 BOTANY OF CROP PLANTS purposes by bakers, confectioners and chocolate manufac- turers. The seeds of soy beans are sometimes used as a substitute for coffee. Soy-bean hay has a comparatively high feeding value. It is recommended as a pasture for hogs. The plant is recognized as a valuable soiling and ensilage crop. Nitrogen-fixing bacterial nodules occur on the roots of the soy bean. VIGNA (Cowpea and Related Species) Description.- — The "Vignas" are usually climbing or traihng herbs, sometimes erect, that are much like the com- mon bean. They differ from the common bean {Phaseolus vulgaris), however, mainly in that the keel of the corolla is short and merely incurved rather than spirally coiled. The leaves are pinnately trifoliate. The flowers are yellowish or purplish, in head-shaped or racemose inflorescences at the ends of long peduncles; these arise in the axils of leaves. The calyx is five-toothed. The stamens are diadelphous (nine and one). The ovary is sessile, many-ovuled, and bears a style that is bearded along the inner side. The pods are hnear, straight or shghtly curved, and two-valved. The seeds are much like the common kidney bean in shape (Fig. 193)- All the Vigna spp. ("Vignas") are natives of warm and tropical regions, and consequently they have been most successfully cultivated in the Southern States. Species.^ — There are but three cultivated species of ''Vignas": Vigna sesquipedalis (asparagus bean), Vigna catjang (catjang), and Vigna sinensis (cowpea). The as- paragus bean has pendant pods i to 3 feet long, and kidney- FiG. 193. — Seeds of i6 varieties of Vigna showing range in variation of shape, size and color. The top three rows are catjangs (Vigna catjang), the bottom two rows are asparagus beans (Vigna sesquipedalis), and the others are cowpeas (Vigna sinensis). {After Piper, U. S. Dept. of Agri.) LEGUMINOS^ 459 Fig. iq.^. 460 BOTANY OF CROP PLANTS shaped seeds 8 to 12 millimeters long. In catjang, the pods are small, 3 to 5 inches long, and usually erect or ascending (Fig. 194). In the cowpea, the pods are 8 to 12 inches long, and become pendant with age. The cowpea is by far the most important, economically. Fig. 194. — A, flowers and fruit of catjang (Vigna catjang); B, flowers and fruit of cowpea (Vigna sinensis). (After U. S. Dept. of Agri.) VIGNA SINENSIS (Cowpea) Description. — The cowpea is a vigorous annual herb with a strong tap root which sends out large side roots almost horizontally for i or 2 feet (Fig.' 195). The greater part of the root system Hes in the first i ^ feet of soil. The varieties vary in habit from prostrate trailing herbs to tall and half-bushy forms. The cowpea has an indeterminate growth, that is, it continues to grow indefinitely, providing environmental conditions are favorable. As in the majority of plants vegetative growth is favored by an abundance of water and LEGUMINOS^ 461 heat, and seed production is stimulated by adverse condi- tions. The lirst pods may come to maturity within seventy to ninety days in the so-called early varieties; on the other hand, some varieties do not even come into bloom under conditions prevailing in the states along the Gulf of Mexico. The flowers are white or pale violet with three bracts at the base of each pedicel. The cowpea flower is capable of self- fertilization, and this is probably the most com- mon occurrence although the flowers are often visited by honey bees or bumble- bees. They are- attracted chiefly by the extra-floral nectaries. The long pods (Fig. 194) are cyhndrical, somewhat curved, and usually constricted be- tween the seeds. The seeds are numerous, usu- ally bean-shaped, spotted, marbled, speckled, or mar- bled and speckled, and have a dark circle around the white hilum. Great variation occurs in pods and seeds. There are two groups of cowpeas based upon pod and seed characteristics; kidney and crowder. The former have compressed pods with kidney- shaped seeds; the latter have thick- walled, cyhndrical pods with globular seeds. Fig. 195. -Cowpea (Vigna sinensis). (After Piper.) 462 BOTANY OF CROP PLANTS Environmental Relations.^ — The cowpea is of tropical origin, and, hence, is adapted to those sections of the country with warm summers; in fact, it requires more heat than corn, and Hke corn, does not thrive where the nights are cool. It is seldom grown north of the Ohio River. It will grow on many different soil types, and will withstand shading. Uses. — The cowpea is of very great economic importance. It is the chief forage plant in the South Central and South Atlantic States. The acreage of the crop is increasing each year. Cowpea hay is prized as food for stock. The plant may also be pastured with hogs or sheep when mature, or with cattle before the peas mature. The plant is being introduced into many locaHties as a catch crop or as a green manure, and is adapted to rotation in a cropping system. The seeds are fed to poultry, and are also recommended as a food for man. The roasted seeds are k substitute for coffee. . ARACHIS HYPOGCEA (Peanut, Goober) Habit, Stem.^ — The peanut is an annual plant with a tap root (Fig. 196). The plant may be low and prostrate, as in the "running types," or upright and bushy, as in the "bush types." The stems are thick, angular, branching, and hairy. Leaves. — The leaves are pinnately compound, usually with two pairs of subsessile, entire leaflets, and no tendrils; the elongated stipules are adnate to the petiole base. Flowers (Fig. 197).- — The flowers are axillary, sessile, and orange-yellow in color. There are two sorts of flowers on the plant, sterile and fertile. Sterile flowers are most numerous in the upper axils, on long, slender pedicels; they have monadelphous stamens (nine united, one abortive) and a minute abortive ovary. The calyx tube is long and slender, and bears on its rim the calyx lobes, corolla, and LEGUMINOS^ 463 stamens; the four superior ]ol)es of the calyx are united, while the inferior one is free. The standard is suborbicular, the wings oblong and free, and the keel incurved. The ovary, at the base of the long, narrow calyx tube, has one to several ovules, and bears a long thread-like style, terminated by a very small stigma. Fh;. 196. — Peanut_(Arachis hypogaea). (After Jones.) Development of Fruit (Fig. 196).- — After the ovules are fer- tilized, the stamens and corolla fall off"; then the flower stalk elongates, bends downward, and carries the developing ovary several inches into the ground. Once buried, the ovary ripens. If the ovar}^ is not brought underground, it withers, and fails to mature. Fruit. — The fruit is a large, oblong, reticulated, indehiscent legume, with one to several ovoid seeds. The "shell" of the ''peanut" is the pericarp; the thin skin that surrounds each seed or pea ("nut") is the testa. The cotyledons are large, and rich in stored food. 464 BOTANY OF CROP PLANTS standard- win^ keel \s\aminal tube Types. — The American varieties may be divided into two large groups: (i) large-podded and (2) small-podded. Each of these is further subdivided into "bush" or "bunch," and "running" types. Well-known varieties in this country are Virginia Bunch, Virginia Runner, Carolina, Spanish, and Tennessee Red. The last-named variety has red- skinned seeds. The nuts in the Spanish variety are smaller than those of the other types. Large-podded varieties are sometimes termed "Jumbos." Environmental Relations. — The peanut is a tropical plant. Consequently, it is raised where the growing season is long, and warm. It succeeds best south of the 36° latitude. The plant is favored by ample sunshine and moder- ate rainfall. It is grown successfully on both sandy and clay soils, although the former are preferred, espe- cially, when the pods are grown for the market and a bright, clean appearance is desired. Uses. — Peanuts are largely used in the roasted state as a human food. Peanut butter has become a very popular food article. One bushel of first-class nuts will yield about 12 pounds of butter. Oil, salted peanuts and peanut candies ovaru Fig. 197. — Flower of peanut (Arachis hypogcea). {After Tanbert.) LEGUMlNUSyi: 465 are other products. The nuts ("goobers") arc fed to hogs, or the animals are turned in to pasture on both the vines and nuts. Peanut oil, pressed from the seeds, is a nearly colorless product, which is employed as a salad oil, to a limited extent in the manufacture of soap, and in the making of oleomargarines and similar compounds. Analyses show that Spanish and Valencia peanuts are richer in oil than Virginia and other common types. The percentage of oil in shelled nuts varies from about 45 to 50 per cent. Peanut meal, the product left after pressing the oil from the seeds, is a high-grade stock feed. Nearly all peanut oil used in this country is made in Europe. The United States imported 1,332,108 gallons of the oil during 1914. LESS IMPORTANT LEGUMES The following list includes several of the less important members, agriculturally, of the Pea Family. Lupinus (Lupines). — Annual or perennial herbs with palmately seven- to fifteen- foliate leaves, and spikes of white, yellow, or blue, showy flowers. They can grow on poor sandy soil, but are little used in this country except to plow under as a green manure. The species used for this purpose are annuals. Lespedeza striata (Japan Clover). — A branched, spreading annual with three-foliate leaves, short petioles, and small flowers in the axils of the leaves. It was introduced from Japan or China to the South Atlantic States, where it is quite largely grown for pasture and hay. It is adapted to clay soils and does well on thin uplands. Onobrychis viciaefolia (Sainfoin). — A deep-rooted perennial with erect stems, odd-pinnate leaves, six to twelve leaflets, and erect, dense racemes of rose-colored flowers. The one-seeded, brown, lens-shaped pods are indehis- cent. The seed loses its viability rapidly, and is slow to germinate. The plant was early introduced into America from Asia, but it is little grown here. It is adapted to dry barren lands that are not suited to clovers and alfalfas. It has been grown with success on calcareous soils. , Omithopus sativus (Serradella). — A low, branched annual, with pinnately compound leaves, and rose-colored or purplish flowers in umbels. The pods 30 466 BOTANY OF CROP PLANTS break into joints. The plant makes good hay and thrives on fairly thin soils, if not dry. It grows best in cool weather, and is not very hardy. Lotus corniculatus (Birds-foot Trefoil). — An annual plant similar to clover. The low-spreading stems are from a long tap root; bright yellow or Pic. 198. — Chick pea (Ciccr arietinum). red flowers occur in small clusters at the ends of the stems; pods are narrow and pendant. It is an Old World plant, but is naturalized in the South where it is sown in mixtures for dry pastures. lkguminos.t: 4^^7 Cicer arietinum (.Chick-pea). — A bushy, hairy annual, i lo 2 fecL liigh, with odd-pinnate leaves and small, white or pink, solitary flowers, followed by short, thin pods. The seeds are pea-like, with a beak-like projection near the hilum. The plant is grown in Europe, Asia, and Mexico for its seeds which are used for both slock and human food. The herbage is unfit for stock because of a poisonous principle. The seeds have been used as a coffee substitute. Trigonella foenum-groecum (Fenugreek). — ^An erect plant with clover- like leaves, and long, pointed pods. It is grown principally for its seeds, which have medicinal properties, and also as an orchard green manure. The seeds are made into a "condition powder" for horses. References B.\RTLETT, G.: The Native and Cultivated Vicieaj and Phaseolea; of Ohio. Ohio Nat., 15: 393-404, 1914. Beal, A. C: Evolution and Pollination of the Sweet Pea. Florist's Exch., 32: 140-141, 1911. Be.vttie, W. R.: Peanuts. U. S. Dept. Agr. Farmers' Bull. 356: 1-40, 1909. The Peanut. U. S. Dept. Agr. Farmers' Bull. 431: 1-39, 1911. Blinn, Philo. : Alfalfa — the Relation of Type to Hardiness. Colo. Agr. Exp. Sta. Bull. 181: 1-16, 1911. French, G. T.: Observations on Medicago lupulina L. Science, n. s., 2, 28: 127, 1908. FucsKO, Mihaly: tjber die biologischen und entwickelungsgeschichtlichcn Verhaltnisse des Pericarps der Papilionaten. Ung. Bot. Bl., 8: 264-265, 1909. Anatomic, Entwickelung und Biologic der Fruchtwand der Papilionata?. Bot. Kozlem, 8: 154-212, 1909. Gregory, R. P.: The Seed Characters of Pisum sativum. New Phytol., 2: 226-228, 1903. Handy, R. B.: Peanuts: Culture and Uses. U. S. Dept. Agr. Farmers' Bull. 25: 1-23, 1896. Headden, Wm. p.: Alfalfa. Colo. Agr. Exp. Sta. Bull. 35: 1-92, 1896. Jones, B. W.: The Peanut Plant. Orange Judd Co., 1885. Kirchner, Oskar: tJber die Wirkung der Selbstbestiiubung bei den Papili- onaceen. Naturw. Ztschr. Land-u. Forstw. Jahrg., 3, Heft i: 1-16, 1905. Martin, J. N. : Relation of Moisture to Seed Production in Alfalfa. Iowa Agr. Exp. Sta. Research Bull. 23: 303-324, 1915. McKee, Roland, and Ricker, P. L.: Non-perennial Medicagos: the Agro- nomic Value and Botanical Relationship of the Species. U. S. Dept. Agr. Bur. Plant Ind. Bull. 267: 1-36, 1913. Oakley, R. A., and Garver, Samuel: Medico falcata, a Yellow- flowered Alfafa. U. S., Dept. Agr. Bull. 428: 1-70, 1917- 4<')8 BOTANY OE CROP PLANTS i'AMMEL, Jm>na C, and Clark, Clarissa: Studies in Variation of Rod Clover. Proc. la. Acad. Sci., 18: 47-53, 191 1. Pammel, L. H., and King, Charlotte M.: Pollination of Clover. Proc. la. Acad. Sci., 18: 35-45, 1911. Pollination of Clover. Contrib. Bot. Dcpt. la. State College, 47: 1-45, 1911. Pfenninger, Urs.: Untersuchung der Fruchte von Phaseolus vulgaris L. in verschiedenen Entvvickelungstadien. Ber. Deut. Bot. Ges., 27: 227-234, 1909. Piper, C. V., and Morse, W. J.: The Soybean; History, Varieties, and Field Studies. U. S. Dept. Agr. Bur. Plant Ind. Bull. 197: 1-84, 1910. Five Oriental Species of Beans. U. S. Dept. Agr. Bull. 119: 1-32, 1914. The Bonavist, Lablab, or Hyacinth Bean. U. S. Dept. Agr. Bull. 318: 1-15, 1915- The Soy Bean, with Special Reference to Its Utilization for Oil, Cake and Other Products. U. S. Dept. Agr. Bull. 439: 1-20, 1916. Piper, C. V.: Agricultural Varieties of the Cowpea and Immediately Related Species. U. S. Dept. Agr. Bur. Plant Ind. Bull. 229: 1-160, 191 2. Soja Max. Jour. Am. Soc. Agron., 6: 75-84, 1914. Piper, C. V., Evans, Morgan W., McKee, Roland, and Morse, W. J.: Alfalfa Seed Production; Pollination Studies. U. S. Dept. Agr. Bull. 75- 1-32, 1914. Piper, C. V., and McKee, Roland: Vetches. U. S. Dept. Agr. Farmers' Bull. 515: 1-28, 1912. ScoFiELD, Carl S.: The Botanical History and Classification of Alfalfa U. S. Dept. Agr. Bur. Plant Ind. Bull. 131: 11-19, 1908. Shaw, 'J'iiomas: Canadian Field Peas. U. S. Dept. Agr. Farmers' Bull. 224: 1-16, 1905. Tracy, W. W.: American Varieties of Garden Beans. U. S. Dept. Agr. Bur. Plant Ind. Bull. 109: 1-173, 1907. Westgate, J. M.: Variegated Alfalfa. U. S. Dept. Agr. Bur. Plant Ind. Bull. 169: 1-63, 1 9 10. Westgate, J. M., and Hillman, F. H.: Red Clover. U. S. Dept. Agr. Farmers' Bull. 455: 1-48, 1911. Westgate, J. M., and Vinall, H. N.: Sweet Clover. U. S. Dept. Agr. Farmers' Bull. 485: 7-39, 1912. Westgate, J. M., Coe, H. S., Wiancko, A. T., Robbins, F. E., Hughes, H. D., Pammel, L. H., and Martin, J. N.: Red-clover Seed Production: Pollination Studies. U. S. Dept. Agr. Bull. 289: 1-31, 1915. Wight, W. F.: The History of the Cowpea (Vigna unguiculata) and Its Introduction into America. U. S. Dept. Agr. Bur. Plant Ind. Bull. 102: 43-59, 1907- WiNTON, Kate, B.: Comparative Histology of Alfalfa and Clovers. Bot. Gaz., 57: 53-63, 1914. CHAPTER XXX LINACEiE (Flax Family) Habit, Stem, Leaf.^ — The species of this family arc annual or perennial herbs, or shrubs. The plants arc tap-rooted, and each tap root bears a number of slender, lateral branches. The stetns are single. The leaves are simple, narrow, nearly sessile, and usually alternate, although sometimes opposite {L. catharlicum). They are linear, linear-lanceolate, or oblong, and sharply awn-pointed, blunt, or rounded at the apex. Inflorescence and Flowers.^ — The inflorescence may be a few-flowered corymb or cyme, or the flowers may be more or less scattered on the branches. I'he flowers (Fig. 2i) are perfect, regular, and five-parted in all respects. The sepals are imbricated and persistent. The petals are wedge-shaped, and may be as long or longer than the sepals. They may be some shade of yellow or blue, orange with rose- tinted base, red, or white. The five stamens have their filaments united at the base. The outer whorl of stamens is wanting or staminodial. The pistil consists of a five- celled ovary, each cell of which bears two ovules. The five styles may be free, united to the stigmas, or united part way from the base. Fruit.- — The flax fruit is a five-celled capsule with two seeds in each cell; each cell is partially or completely divided into two by a false partition between the two seeds, thus making the cMpsulc apparently ten-celled (Fig. 2t). 4^0 470 BOTANY OF CROP PLANTS The Names Derived from "Linum." — This family contains but one important genus, Linum. The name Linum is the latin for flax. The word "linen" means made from flax or of flax. It is from these and other similar foreign names that we get our common words linen, lint, linseed, and line; Geographical, and Environmental Relations.^ The family has about 135 species, which are widely distributed over the world. The important commercial species is L. usitatissi- mutn. All cultivated flax varieties in this country are treated as belonging to this one species. Flax is raised under a wide variety of climatic conditions and soils. In regions with low rainfall, the crop is of little value for fiber, and hence is grown chiefly for its seed. A fair quality of fiber flax is produced in certain sections of the United States where the rainfall is 25 to 30 inches. The water requiremen4: of flax is higher than that of any of the cereals, being about three times that of millet and sorghum. LINUM USITATISSIMUM (Common Flax) Habit, Root. — Common flax is an upright herb which under cultivation grows to a height of from i to 4 feet (Fig. 199). It is a dainty surface feeder with a small root system ; this consists of a slender tap root sparingly supplied with slender branches in the first 12 to 18 inches of soil. The tap root runs downward vertically to a depth of 3 to 4 feet in some cases. No network of roots is formed near the surface of the soil. Long-stemmed flax as compared with other varie- ties appears to have a weaker root system and less root penetration. Deep planting is adverse to root development of flax. Stem. — The stem is simple, erect, and branching in the upper part, rarely at the base. As it matures, it becomes LINAGES. 471 rigid, at the same time retaining considerable elasticity due to the bast fibers. Flax Fibers.- — Three tissue areas are recognizable in the stem: pith, wood, and bark. The flax bark contains the bast or flax fiber cells. These bast fibers give flax straw Fig. 199. — Cninmnn flax (Linum usitatissiniiim). its great financial value since they make up the part from which linen is made. Each bast fiber is a single cell, 25 to 30 millimeters long, and cylindrical in shape. Leaves, Inflorescence and Flowers.— The leaves are narrow, entire, and blunt at the apex. The inflorescence 472 BOTANY OF CROP PLANTS is loosely cymose. The flowers vary in color from white to deep blue. The same plant always bears flowers of the same color. Yellow-flowered varieties are not found in this species. The petals are large, conspicuous, wedge- shaped, and about twice as long as the sepals. Pollination.- — Studies of flax varieties indicate that there is close-pollination. Individual flowers produce seed freely, whether associated with other flowers or not^v Examination of flax flowers at the proper time shows anthers in close proximity to the stigmas, and the latter covered with pollen. Mature Fruit.- — The flax fruit (Fig. 21) is a round capsule known commercially as the ''seed ball." The seed ball is com- posed of five fused carpels. The balls are divided into five true cavities or locules by means of five true partitions (septi) extending from the wall (pericarp) to the axis. Each locule contains two seeds' and is divided more or less incompletely into two loculi by means of false septi. The seed balls are ^-^ inch or more in diameter. When fully ripe, they are easily separated into parts at the points where the carpels are joined. Seeds. — The seeds vary in length from 3-7 to y^ inch. They are lenticular, compressed, and shghtly longer than wide. They have a very smooth, polished surface and vary in color from yellow to dark brown. Light brown is the standard color. A mucilaginous material which quickly becomes sticky (viscid) in hot water is found filling the epidermal cells of the seed. It is this substance which gives flax its medicinal value. The embryo is surrounded by a thin layer of endosperm which, in the mature seed, contains starch. Geographical. — Common flax is a native of Europe. It is now widely dis- tributed over the world, being grown commercially in many countries. India is a heavy producer of seed, and in Argentina it is grown extensively for oil. LINACE.E 473 Types and Varieties.— There are large-seeded and small- seeded varieties. The large-seeded types are sometimes known as Sicilian flax, and are grown almost entirely for their seed, rather than fiber; there are both blue- and white- flowered sorts. The small-seeded types are grown both for fiber and seed; there are both blue- and white-flowered varieties. The fiber flaxes have more slender stems, fewer basal branches, and a more compact panicle than the seed flaxes. Uses. — Linseed Oil. — The manufacture of linseed oil is carried on in manufacturing plants having investments of millions of dollars. The seeds are crushed, heated to about i65°F., placed in tanks or cylinders, and while hot, treated with naphtha to extract the oil. From 30 to 39 per cent, of the seed is oil. Linseed oil is used in the manufacture of paints, patent leather and varnishes. Linoleum is a prepara- tion of linseed oil which is hardened by treating with sulphur chloride or by exposure to heated air. It is sometimes used as a substitute for india-rubber. Oil cloth and other sorts of floor cloth, are made by mixing ground cork with the hardened linseed oil (linoleum), and pressing upon canvas. Oil Cake and Oil Meal. — The residue from the crushed flax seeds is known as oil cake. It is sold either as oil cake or ground into a meal, anc^ used as a stock food. Belgium and Holland are our chief customers for linseed-oil cake. Flax Fiber. — ^Linen is made from flax fiber. Our finest linens are from foreign grown flax, the best of which is grown in Belgium in a region through which flows the River Lip. The creamy Flemish flax from which the finest linen fabrics are made is grown in this section. Flax fiber is also utilized for making thread, carpet yarns, fishing lines, seine twines, etc. It is also employed to some extent for upholstering, for insulating cold-storage plants, refrigerator cars and ice i! (0 h z UJ (0 tuco a: UJ UJ o °:< 8!- o < U! Sao 3. Q UJ z o << UJ _J < UJ* o a: U£ o i 2 u 9^ a 00000 00000 00000 000000 000000 i25S LINAGES 475 boxes. A fine grade of paper (linen paperj is made from linen rags. Linen paper treated with sulphuric acid gives a parchment which takes the place of ''sheep skin." Preparation of Flax Fiber .^ — Flax plants for fiber are pulled by hand and tied into small bundles. The bundles arc shocked and permitted to cure. After the seed is thrashed from the plants, they are spread out thinly on the ground and exposed to the weather for several weeks. The exposure brings about a partial separation of the bark and wood. This process is known as retting. It is essentially a fermenta- tion process. Retting is also carried on in stagnant water and fresh running water. Most French and Belgium flax is retted in running streams, while most Irish flax is retted in stagnant water. The bundles of straw are then pounded by hand or bent by machinery, until the fiber is almost entirely freed of other stem parts. The next treatment, known as "scutching," consists in beating the fibers until any fragments of bark or wood or course fibers, not removed in the breaking process, are eliminated. Paddles, operated by hand or by machinery, are used in the scutching process. The fibers are sorted and baled, and kept in this form until ready to be spun. Production of Flax. — Most of the flax for fiber is grown in the European countries. The United States is one of the largest seed-producing countries but raises a ver}^ small amount of fiber. In 1914, Argentina produced 39,171,000 bushels of flax seed, British India 15,440,000 bushels, and United States 13,749,000 bushels. The large flax seed-pro- ducing- States in 19 14 were North Dakota, Minnesota, Montana, South Dakota, and Kansas. CHAPTER XXXI RUTACEiE (Rue Family) Description.- — This family is represented by trees, shrubs, and herbs. The leaves are alternate or opposite, simple or compound, exstipulate, and glandular-dotted. The glands, which appear as translucent dots, are internal. They vary somewhat in size and shape. The flowers (Figs. 200 and 201) are solitary or in small axillary or terminal cymes. The sepals are four to five in number, but sometimes absent. There are as many petals as sepals, and they are either hypogynous or perigynous. The separate or united stamens are attached to the receptacle, and vary considerably in number; tj^e anthers are two-celled, usually versatile, and introrsely dehiscent. The two to five carpels may be distinct, or united to form a compound pistil. The receptacle is frequently modified to form an annular disk (Fig. 201, B). The fruit is a capsule, berry, drupe, or samara. The seeds are oblong or kidney- shaped, and have a straight or curved embryo, a fleshy endosperm, and fleshy cotyledons. The seeds of lemon may germinate in the fruit. Geographical. — The family is well represented in the tropical countries. There are, according to Britton and Brown, about no genera and 880 species. A few members of the Rue Family are native to the United States; chief of these are the prickly ash (Xanthoxylum), hop-tree (Ptelea), and torch- wood {Amyris). None of the Citrus species are native of America. 476 Fig. 200. — Floral diagram of Citrus. (After Eichler.) RUTACE.-l': 477 Kky to Important Genera of Rutace^^ Leaves trifoliate, Poncirus (trifoliate orange). Leaves unifoliate. Ovary three- to seven-celled; ovules two in each cell; stigma cavernous, Forliinella (kumquat). Ovary eight- to fifteen-celled; usually more than two ovules in each cell; stigma solid, Citrus (orange, lemon, grapefruit, lime, etc.). Fig. 201. — Sour orange (Citrus aurantium). A. flowering branch; B, lengthwise section of flower; C, lengthwise section of fruit; D, seed. (After Wossidlo.) CITRUS (Citron, Lemon, Orange, etc.) Habit, Roots. — Citrus species are aromatic, mostly thorny shrubs or small trees with the spines disposed singly in the leaf axils. The sweet orange tree is a surface feeder; almost its entire root system is in the first i8 inches of soil. The sour orange root system penetrates to a much greater depth. The citrus plant is different from most plants in the total absence of root hairs. Absorption is carried on by the fibrous roots which are abundant and capable of rapid growth. Leaves. — The leaves are glandular-dotted, winged-petio- ^Hume has been followed largely in the discussion of this group. 478 BOTANY OF CROP PLANTS late, glaucous, leathery, evergreen, and unifoliatc (with the exception of Citrus trifoliate) ; the leaf stalk is usually articu- lated to the blade and also to the twig. The hfe of the leaf depends upon the kind of wood upon which it is borne. On the fruiting branches, orange leaves, for example, remain on the tree about fifteen months, while on twigs with vigorous vegetative growth they may remain on the tree for three or four years. The leaves of trifoliate oranges fall in the autumn. The aromatic odor of freshly crushed leaves of citrus plants is due to the numerous glands which are scattered over its surface. Flowers. — The white or purplish-pink flowers are sohtary, or in small axillary or terminal cymes or panicles. The flowers are hermaphroditic; the calyx is three- to six-toothed; the corolla has four to eight separate thick segments (petals) ; and there are 20 to 60 stamens, united at their bases to form groups; the ovary possesses 8 to 75 cefls and is subtended by a cushion-shaped disk (receptacle). Pollination and Fertilization. — Some varieties of citrus plants require fertilization in order to set fruit, while others mature parthenocarpic ("seedless") fruits. Some varieties of oranges require cross-fertilization, and more- over, will not set fruit unless pollen is derived from certain congenial varieties. Pollination may occur without the visitation of insects. The time for complete fertihzation after pollination varies from thirty hours in Satsuma oranges to four weeks in trifoliate oranges. Parthenocarpic varieties seldom bear viable pollen. In navel oranges there is no pollen in the anthers at flowering time. Fruit.- — The fruit is a modified berry (hesperidium) ; it is spherical or spheroidal and is made up of a thick, leathery ''rind" with numerous lysigenous oil glands, and a juicy pulp composed of numerous stalked "juice sacks." RirTACE^ 479 Bonavia considers the rind of citrus fruits to consist of a whorl of modified leaves that has grown up about the carpels. The number of carpels ("sections") varies in the same variety. Seeds. — There are from one to eight light-colored seeds in each cell of the fruit. The seed coat is cither leathery or membranous; endosperm is lacking; each seed has two or more embryos with flesh}', hypogean cotyledons. The polyembryonic condition of citrus fruits is characteristic. As many as thirteen seedlings from one seed have been noted. Strasburger has shown that embryos of citrus seeds may be derived from nucellar cells, as well as from fertilized ova. He has designated such embryos as "adventitious." Hence, in the polyembryonic seed, there are two sorts of embryos: (i) those formed by the union of egg nucleus and sperm nucleus, true sexual embryos; and (2) "adventitious" embryos formed by vegetative growth. Obviously, the seedlings from adventitious embryos may be used for propo- gation with confidence that they will come true to the plant which bore them. Early disintegration of embryo sacs appears to be prevalent in citrus fruit. This may be one cause, along with infertile pollen, of seedless fruits in this group. Geographical. — Citrus species are mostly natives of the Malaj^ Archipelago, and adjacent Asiatic territor}'. Citrus fruits are grown only in those parts of the United States where there is an almost continuous growing season, and where freezes seldom occur. Key to Principal Species of Citrus Petals white inside, purplish or reddish outside. Stamens 30 to 40; fruit 6 to 9 inches long, its skin thick, C. mcdku (citron). Stamens 20 to 30; fruit about 3 inches long, its skin medium thick, C. limonia (lemon). 480 BOTANY or CROP PLANTS Petals white both on the inside and outside. Leaves wingless or narrowly winged. Fruit small, i^ to 2^2 inches in diameter, its skin thin, C. aiiranUfolia (lime). Fruit large, its skin thick. Tree small, 12 to 20 feet tall; skin of fruit easily removed, C. nobilis (king orange). Tree large, 20 to 40 feet high; skin of fruit not easily removed, C. sinensis (common sweet orange). Leaves broadly winged. Fruit large, pale lemon-yellow when ripe, C. grandis (grapefruit, pomelo, shaddock). Fruit medium-sized, orange-colored or reddish when ripe, C. aurantium (sour or Seville orange). CITRUS MEDICA (Citron) Description — This is a shrub or small tree with short, stout thorns; the leaves are large, crenate or serrate, and its petioles are wingless; the large flowers are usually in clusters of 3 to 10; their petals are white above, and reddish purple below; the stamens are as many as 30 or 40; the ovary usually has from 9 to 10 locules; the fruit is large, 6 to 9 inches long, rough or warty, lemon-yellow when ripe, its skin thick, the pulp scarce and very acid, and the juice sacks small and slender. In the ''lingered citron," the fruit segments are separated into a number of finger-like projections. Geographical. — This species is probably a native of India. It is cultivated most extensively in the Mediterranean region, and to some e.xtent in this country, "Citron."- — The commercial "citron" is the dried fruit of Citrus medica. Before the fruit is candied, it is placed in brine to extract the undesirable oil in the skin. The fruit is then boiled for an hour or so in a sugar solution to which has been added some glucose. The glucose prevents the product from becoming too brittle. It is then allowed to RUTACE.E 48 1 stand in the syrup for about a month, and subsequently- boiled in a pure sugar syrup. CITRUS LIMONIA (Lemon) Description. — The lemon tree is small, from lo to 20 feet in height, with short, stout thorns; the leaves are 2 to 3 inches long, long-ovate, sharp-pointed, serrate, and its petioles wingless; the large flowers are axillary, usually solitary, Fig. 203. -A citrus orchard in Southern CaUfornia {From Calif. Agr. Exp. Sla.) sometimes in small clusters; their petals are white inside, and purplish above; the stamens are usually between 20 and 3c in number; the ovary has 7 to 10 locules. There are three sorts of flowers in the lemon: (i) perfect flowers, (2) flowers with rudimentary pistils and normal stamens, and (3) flowers that fail to develop beyond the bud stage. Ihe first class is the only one to set fruit. The fruit is about 3 31 482 BOTANY OF CROP PLANTS inches long, light yellow when mature, its skin medium- thick, the pulp abundant and acid, and the juice sacks long and pointed. The fruit requires about nine months to reach maturity. Geographical. — The lemon is probably a native of India. It is cultivated extensively in the Mediterranean region, and to a considerable extent in Cali- fornia and Florida. Colpr of Lemon Fruit. — ^Lemons are picked when they reach a size demanded by the market, regardless of the degree of maturity. Hence many of the lemons, when picked, are dark green, and not the lemon-yellow of those we buy in the market. The fruit is colored and ripened be- fore shipment. If they are not to be shipped for several months, they are placed in storage houses where coloring and ripening goes on gradually. However, if they are to be shipped soon after picking, the coloring process is hastened. This is done by putting theni in "sweat rooms" that are kept at a temperature between 90° and 95°F. The proper color is obtained by this treatment within four to six days. Uses. — ^Lemons are used in the home for lemonade, as an ingredient in a number of prepared foods, as a stain-remover, and as a bleaching agent. One of the chief uses of lemons is in the manufacture of lemon extract. Lemon Extract. — This ranks second to vanilla extract in the quantity consumed. Sicily now produces the world's supply of lemon oil. Cull lemons are utilized for the pro- duction of the oil. Lemon extract is made by dissolving 5 parts of lemon oil in 95 parts of strong alcohol. Lemon oil is secreted by special cells in the outer surface of the rind. About 95 per cent, of the lemon oil produced is obtained from the lemons by the sponge method, the remainder by the 7nachine method. There are two sponge methods, known as the two-piece, and three-piece sponge methods. In the former RUTACE^ 483 method the lemons are cut by hand into two pieces, and the pulp removed; the rinds are then thoroughly soaked in water, and after standing for several hours, passed on to the spongers. The apparatus of the sponger consists of a round stick about I inch in diameter, placed across the top of an earthenware bowl about 8 inches tall and the same in diameter, and three sponges. A flat sponge is hung across the stick, upon this another thicker sponge, and finally a third above this. The third or upper sponge is cup-shaped; into this depres- sion, the lemon rind is inserted. By main strength the operator presses upon the sponge, repeating this pressure, after turning the rind over several times. Only i pound of oil is secured from 1,600 to 2,200 lemon halves. The three- piece method differs but sHghtly from the preceding. CITRUS AURANTIFOLIA (Lime) Description.- — This is a small straggling tree or shrub, with numerous, small, very sharp thorns; the small leaves are elliptic-oval, crenate, glossy-green, and its petioles are nar- rowly, but distinctly, winged; the flowers are small, and usually produced in clusters of 3 to 10; the petals are white both above and below; the stamens range from 20 to 25; the ovary commonly has about 10 locules; the fruit is small, from i^^i to 2)4, inches in diameter, oblong, or rounded- oblong in outline, light yellow when ripe, its skin thin, the pulp abundant, greenish and very acid, and the juice sacks small, oval, and pointed. Geographical.- — The lime is a native of India and southeastern Asia. It is cultivated in many tropical countries, and to some extent in Florida and the Keys. The fruit is used in the making of "limeade." "Limequat." — The "hmequat" is a hybrid between a kumquat and the Mexican lime. 484 BOTANY OF CROP PLANTS CITRUS SINENSIS (Common or Sweet Orange) Description. — The sweet orange tree is 25 to 40 feet high, round-topped, and usually bears slender, flexible, blunt spines; the leaves are oval or ovate-oblong, and the petioles are narrowly winged, articulated both with the blade and the twig; the JJo7vers occur singly or in small cluster; the petals are white above and below; there are from 20 to 25 stamens; the ovary has 10 to 14 locules; the fruit is subglobular, Hght orange to reddish, smooth, the pulp abundant and sweet, and the juice sacks spindle-shaped. Geographical. — The sweet orange is the most widely cultivated of all citrus fruits; it is probably a native of southeastern Asia. TjTpes. — There are a number of groups or types of sweet oranges; the four principal ones are Spanish oranges, Med- iterranean oranges, blood oranges, and navel oranges. Spanish oranges have large, coarse-grained fruit. Mediterranean oranges are of good quality and fine-grained. Blood oranges have red pulp or white pulp streaked with red; the fruit is of good quality. Navel oranges are so named on account of the umbilical mark at the apex of the fruit. This mark is due to the protrusion of additional carpels developed within the fruit. Uses. — Whereas oranges were once regarded as luxuries, they are now produced in such quantities and sold at such prices as to be within the reach of the majority of people. Oranges are used mainly as a fresh dessert. Orange extract is made by dissolving orange oil in strong alcohol. Up to the year 191 1, almost the entire world's supply of orange oil came from Sicily, Italy and adjacent parts of southern Europe. Since then the West Indies have developed the industry. The oil is used in the manufacture of perfumes, soaps, and flavoring extracts, and to a slight extent as a drug. RUTACE.E 485 Hood and Russell have recently pointed out that the ex- traction of sweet orange oil is a commercial possibility in this country, and that waste oranges may be utilized. CITRUS NOBILIS (King Orange) Description. — The King orange tree is 12 to 20 feet tall, with slender, drooping branches, and thornless, or with small sharp spines; the leaves are small, lanceolate to oval, and the petioles are wingless or very narrowly winged; the flowers occur singly or in small clusters; the petals are white above and below, fleshy and recurved; there are from 18 to 24 stamens; the ovary has 9 to 15 locules; the fruit is oblate, orange to reddish in color, its peel loose and easily removed, the pulp sweet or sub-acid, and the juice sacks broad and blunt. Varieties. — Citrus nohilis var. deliciosa is the mandarin orange. In this variety are included the tangerine varieties, which have an easily removable skin and segments that come apart readily, also the tangelo which is a hybrid between the tangerine and the Bowen grapefruit. Citrus nohilis var. unshiu is the Satsuma or Unshiu orange. It is a small, spineless, dwarf tree, and very hardy. CITRUS GRANDIS (Grapefruit, Pomelo, Shaddock) Description.— This species is a large tree, 20 to 40 feet in height, with slender, flexible spines, if present; the leaves are large, ovate, crenate, broadly rounded at the base, and the petioles are broadly winged and articulated ; the flowers are borne singly or in clusters of 2 to 20; the petals are white both above and below; there are from 20 to 25 stamens, with large linear anthers; the ovary has from 11 to 14 locules; the fruit is very large, 4 to 6 inches in diameter, globose, oblate or pear-shaped, pale lemon-yellow when ripe, its skin smooth, 486 BOTANY OF CROP PLANTS the pulp peculiarly acid or sub-acid, and the juice sacks large and spindle-shaped. Fig. 204. — Pomelo (Citrus grandis), in the fourth summer. {From Calif. Agr. Exp. $ta.) Geographical. — The species is a native of Polynesia and the Malay Archi- pelago. It is now grown in the United States. RUTACEiE 487 Variety and Name.- — The name grapefruit is the one that this species is known by commercially. Shaddock is a horti- cultural variety, the fruit of which is much larger than the common grapefruit. It is a coarse, thick-skinned fruit, with thick, leathery septa between the locules, and is of no com- mercial importance. The name pomelo is now recognized by most horticulturists. Grapefruit is a well-known breakfast fruit. CITRUS AURANTIUM (Sour or Seville Orange) Description. — The sour orange tree is 20 to 30 feet high, and bears long, flexible, blunt spines; the leaves are 3 to 4 inches long, wedge-shaped at the base, pointed at the tip, and the petioles are broadly winged; the flowers are borne singly or in small axillary cymes; the fragrant glandular- dotted petals are white above and below; there are from 20 to 24 stamens; the ovary has 6 to 14 locules; the fruit is globose, orange-colored or reddish, rough, the pulp acid, and the juice sacks small and spindle-shaped. Geographical. — The sour orange is probably a native of southeastern Asia. It is cultivated in the United States, being used as a stock on which to bud other citrus fruits. Other Species of Citrus. — Other Citrus species of less commercial importance in the United States are C. mitis, the Calamondin orange, C. ichangensis, Ichang lemon, and C bergamia, bergamot. FORTUNELLA (Citrus) (Kumquat or Kinkan) Description. — The kumquats are evergreen shrubs with simple, glandular leaves; the scented white flowers are single or in clusters of three or four, and axillary; the early flowers in the spring are usually without pistils; there are four times as many stamens as petals; the ovary has three to seven cells, 488 BOTANY or CROP PLANTS and each cell contains two ovules; a characteristic feature of the flower is the cavernous stigma; the fruit is small, i to i^^ inches in diameter, its rind usually thick, fleshy, spicy, CO and aromatic, its juice acid, and its seeds small and pointed; there may be one or two crops of bloom and fruit in a growing season. Species.—The two most common species of Forlunella are F. margarita, the Oval or Nagami kumquat, and F. RUTACE^ 489 japonica, the Round or Marumi kumquat. The former is athornless shrub or small tree with oval fruit, the latter a thorny shrub with globose fruit. F. crassifolia is the Meiwa kumquat, and F. hindsii, the Hongkong wild kumquat. The latter is considered by Swingle to be the wild stem form of our Citrus species. Uses.- — The kumquats are shrubs grown as ornamentals, and also for their fruit, which is eaten raw and entire. PONCmUS, (Trifoliate Orange) Description. — The trifoliate orange is a low tree, seldom over 15 feet high; the older branches are thorny, the thorns being i to 1^2 inches long, and flattened at the base; the characteristic deciduous trifohate leaves are composed of thin, elliptical, crenate or dentate leaflets; the flowers usually appear before the leaves, singly or in pairs in the leaf axils; the five sepals are greenish yellow in color, and pointed at the tip; the corolla is white; the fruit has a light orange color, is rough, and covered with short hairs; it is of no com- mercial value; the numerous seeds differ from those of other alhes in being oval, roimded at one end and blunt-pointed at the other. The pulp is acid, bitter, and gummy. A Hardy Orange. — The trifohate orange is a native of China and Japan. It is the hardiest of our citrus species, and for that reason has been used in crosses with less hardy, but more desirable species, in the hope that hybrid forms would be secured which would combine hardiness and de- sirable fruit characters. Hybrids of trifoliate and sweet oranges are known as citranges. Varieties of citranges are Colman, Morton, Rusk, Rustic, and Savage. References BiERMANN, M.: On the Structure and Development of the Fruit of Citrus Vulgaris. Arch. Pharm., 235: 19-28, 1897. 490 BOTANY OF CROP PLANTS BoNAViA, E.: Oranges and Lemons of India, vol. i. CoiT, J. E.: A Study of the Factors Influencing Seed Formation in Citrus Fruits. Calif. Agr. Exp. Sta. Rpt., 105-106, 1914. Citrus Fruits. The MacMillan Co., 191 5. Hood, S. C, and Russell, G. A.: The Production of Sweet-orange Oil and a New Machine for Peeling Citrus Fruits. U. S. Dept. Agr. Bull. 399: 1-19, 1916. Hume, H. Harold: Pomelos. Fla. Agr. Exp. Sta. Bull. 58: 385-421, 1901. The Kumquats. Fla. Agr. Exp. Sta. Bull. 65: 555-566, 1902. The Mandarin Orange Group. Fla. Agr. Exp. Sta. Bull. 66: 571-594, 1903. Citrus Fruits and Their Culture. Orange Judd Co., 1913. Ikeda, Tomochika: On the Parthenocarpy of Citrus fruits. Jour. Sci. Agr. Soc. Tokyo, 63, 1904. Osawa, L: Cytological and Experimental Studies in Citrus. Jour. Col. Agr. Imp. Univ. Tokyo, 4: 83-116, 191 2. Strasburger, E.: tjber Polyembryonie. Jenaisch. Zeitsch. Naturwiss., 12: 647-670, 1878. Webber, H. J.: Complications in Citrus Hybridization Caused by Poly- embryony. Science, n. s., 11: 308, 1900. CHAPTER XXXII VITACE^ (Grape Family) Family Description.— ^Members of the grape family are either climbers or erect shrubs with nodose joints. There is an abundance of watery sap. The leaves are alternate and petioled, either simple {Vitis) or compound {Parthenocissus) (Fig. 206). The inflores- cence is commonly a panicle (Vitis) or a cyme {Partheno- cissus). The flowers (Fig. 210) are small, greenish, perfect or polygamo-dicecious (perfect flowers on one indi- vidual and imperfect on another). The calyx is en- tire or four- to five-toothed. The four to five petals are either separate or united and fall away very soon after development. Stamens are four to five in number and opposite the petals. The single ovary has two to six cells with one to two ovules in each locule. The fruit is commonly a two-celled berry. Geographical.— There are about 10 genera and 450 species in this family, many of which are natives to tropical countries. 491 Fig. 206.— Compound digitate leaf of Virginia creeper (Parthenocissus quinquefolia). 492 BOTANY OF CROP PLANTS Key to Important Genera The three most important genera are VUis (grape), Cissus (pepper vine) and Parthenocissiis (Virginia Creeper and American Ivy). These may be distinguished as follows (as far as our species are concerned) : Leaves simple or pinnately compound. Petals united into a cap, falling away without separat- ing (Fig. 210), VUis (grape). Petals separate, spreading, Cissus (pepper vine). Leaves digitately compound, Parthenocissiis (Virginia creeper, American ivy). VITIS (Grape) Stems. — Grapes are climbing or woody vines with tendrils. The stem is jointed. The internodes have a large pith. In many species there is a woody tissue (diaphragm) at the nodes separating the pith; in others this woody tissue is absent (Fig. 207). In pruning the vines, the practice is to make the cut through the nodes rather than through the internodes; by cutting through an inter- node, the pith shrinks, leaving a hollow in which water may collect and rotting set in. Grapes have a tendency to produce suckers and water sprouts. The former arise from below or near the surface of the ground and should be removed. Water sprouts- arise from dormant buds above ground. They do not produce fruit. If dormant buds de- velop, producing these sterile shoots, it in- dicates that there is not a sufficient number of fruit buds to take care of all the sap coming to aerial parts. Water sprouts should be removed during winter pruning. Tendrils, morphologically, are modified stems. This is Fig. 207. — Two types of grape stems cut in me- dian lengthwise section. A, south- ern fox grape (Vitis rotundifo- lia) with pith con- tinuous at the nodes; B, old world grape (V. vinifera) with pith interrupted at the nodes. {After Hedrick.) VITACE^ 493 shown by the fact that they sometimes bear small leaves or flowers. In the Fox grape (Fig. 2c8), there is either a tendril or an inflorescence opposite each leaf. This continuity Fig. 208. — Northern fox grape (Vitis labrusca). is somewhat variable, however. In all other species, there are two successive leaves with a tendril or inflorescence oppo- 494 BOTANY OF CROP PLANTS Fig. 209. — Fruit-bearing shoot of river-bank grape (Vitis riparia). (After Hedrick.) VITACE^ 495 I site each, while the third leaf is without a tendril, and so on, there being no tendril or cluster for each third leaf (Fig. 209). A tendril or inflorescence terminates the stem growth. Flower clusters are borne on growing shoots. In the spring, a bud sends out a growth; flower clusters appear early near the base of this growth, while the shoot continues to grow until the end of the season. Vitis labrusca averages three to six clusters to a cane; all other species average two to a cane. This shoot bears a number of buds, each of which may, the following season, produce another shoot, in turn bearing fruit clusters. If all these buds are allowed to develop, the fruit developed on the shoots will be very small. Hence in practice it is found necessary, each year, to prune back the current season's growth, leaving only a few buds to develop the succeeding year. Grapes are commonly propagated from stem cuttings. The European grape has been grown vegetatively for over 5,000 years. Leaves. — The grape leaf is simple, palmately lobed or dentate, alternate, with grooved petiole and small stipules. The leaves of the different species vary as to size, shape, number of lobes, nature of petiolar groove, and surface. Inflorescence and Flowers. — The grape inflorescence is a compact panicle. As has been indicated, the clusters are borne at the basal nodes of the current season's growth, opposite a leaf or a tendril. In Vitis labrusca, there are from three to six inflorescences to a cane, while in all other species the average is two inflorescences per cane. In the wild state, grape vines are of two types: some vines bear self-sterile perfect flowers and other vines bear only staminate flowers. In cultivated forms, there are two types of perfect flowers; those in which the stamens are upright and those in which the stamens are reflexed. In the first 496 BOTANY OF CROP PLANTS case, the pistil is fully developed and the pollen potent, while in those flowers with reflexed stamens, the pollen is more or less impotent. Flowers without stamens do not occur. Among cultivated European varieties, only perfect flowers are common. This has resulted from selection. '^^cap of 5 petals -^-nectar Fig. 210. — Grape flower, opening. X 20. The flowers (Fig. 210) are hypogynous and regular. The calyx consists of a narrow rim at the base of the flower. The corolla has five united, greenish petals; in the bud, they form a cap (Fig. 210) over the stamens and pistils. When the flower opens, the petals become loosened at the base but remain united by the tips. Stamens are five in number and VITACE^ 497 there is an equal number of nectar glands between. The one pistil is two-celled and two-ovuled. The fruit is a berry. Dorsey has cited marked variations in the flowers of the genus Vitis: stamens may vary from three to nine; petals, nectariferous glands, and carpels have a corresponding numerical variation. Opening of Flower and Pollination. — Flower Opening. — The opening of the grape flower is indicated by the breaking away of the petals at the base (Fig. 2 10) . In some instances, all the petals break away at about the same time; at other times, one petal may initiate the process, and be followed by the others. The cap of live petals, adhering at their apices, finally falls off. The rate of flower opening varies from a few minutes to several hours. The anthers seldom open until the cap falls off. Most grapes are insect pollinated. Self-sterility. — Many cultivated varieties of grapes are self-sterile; this is due, for the most part, to impotent pollen. Some cultivated varieties are perfectly self-fertile, others partially self-fertile, and still others entirely self-sterile. As has been indicated, perfect flowers bearing reflexed stamens usually have impotent pollen. However, in some cases, perfect flowers with erect stamens also bear impotent pollen. As a rule, the self-fertile varieties, those that can develop marketable clusters when self-fertilized, have long stamens. Self-sterile varieties, those that cannot produce marketable clusters of fruit when self-fertiHzed, usually possess short stamens. However, long stamens and short stamens are not absolute criteria of self-fertility and self- sterihty respectively. With but few exceptions, the strongly self-sterile varieties are hybrids. Booth suggests that the grape is "now in a state of evolution from an assumed older hermaphrodite form to forms which are essentially staminate 498 BOTANY OF CROP PLANTS and pistillate." He finds all gradations between ''pseudo- staminate" and ''pseudo-pistillate" forms among wild species. Grape Pollen. — In a study of grape pollen, Booth found that self-sterile pollen differs from self-fertile pollen. In the self-fertile form, the grain is surrounded by a mucilaginous substance which causes them to stick together; the grain is oblong in shape, symmetrical, and blunt at the ends. Self- sterile pollen has no mucilaginous substance about it; it is irregular in shape and more pointed at the ends. Self- fertile and self-fertile pollen may be mixed in the same variety. The degree of self-sterility or self-fertility seems to vary with environmental conditions. "Couloure" of Muscat Grape.^ — This valuable raisin grape has a tendency to drop its blossoms without setting fruit. This trouble is known as "couloure." It results from a lack of fertihzation. This is due to the fact that in this variety stamens are shorter than the pistil, that the pollen has a tendency to stick together in masses which makes its dis- tribution less certain, and to the rather frequent development of imperfect pollen grains. The difficulty is largely overcome by planting, in the Muscat vineyard, varieties that produce an abundance of viable pollen, and that blossom at the same time as the Muscat. These 'varieties will furnish pollen for fertilization of Muscat flowers. Flowers in Wild Grapes. — Grapes in the native condition differ from those in cultivation. The wild forms seldom bear self-fertile perfect flowers. In these, there are just two sorts of vines: (i) staminate, and (2) self-sterile hermaphrodite. There are no self-fertile hermaphrodites. The staminate flowers have abortive pistils, and the so-called pistillate forms retain their stamens, but they are abortive. ViTACE^: " 499 Key to Most Important Species of Vitis' Skin of mature berry not separating freely from the pulp, Vilis vinijcra (Old World grape). Skin of mature berry separating readily from the pulp. Nodes without diaphragms (Fig. 207, A); tendrils forked, Vilis rolimdifolia (Southern fox grape). Nodes with diaphragms (Fig. 207, B); tendrils forked. Leaves and shoots glabrous at maturity and without bloom. Leaves broader than long; petiolar sinus usually wide and shallow, V. rupeslris (sand grape) . Leaves ovate in outline; petiolar sinus usually medium to narrow, V. riparia (river bark grape). Leaves rusty or white tomentose or glaucous blue below. Leaves not covered with a thick, dense felt-like tomentum when fully grown, V. astivalis (summer grape). Leaves covered with a dense, thick, felt-like tomentum when full>- grown, V . hibrusca (Northern fox grape). Vitis vinifera (Old-World Grape, Wine Grape, Raisin Grape). — The Old-World grape is not as large a plant as most American species. The leaves are thin, smooth, and three- to seven-lobed; they may be smooth or woolly-hairy when young; the lobes are rounded or pointed, and their margins coarsely toothed. The oval, oblong, or globular berries are in long and broad clusters. The varieties of this species have a high sugar content. On this account, they make better wine and raisins than American varieties. American varieties are table grapes; European varieties are wine and raisin grapes. The latter are now grown in California, where the wine and raisin in- dustries have developed to considerable importance. V. vinifera is not resistant to the attacks of Phylloxera, a scale attacking the leaves and roots. American varieties are comparatively more resistant to these insects and on this account are used as stocks upon which European varieties are grafted. iThe key is adapted from "The Grapes of New York," by Hedricb. 500 BOTANY OF CROP PLANTS Vitis vinifera is probably a native of western and southern Asia. Vitis rotundifolia (Southern Fox Grape). — This is usually a very vigorous, high-climbing grape, with hard wood and smooth bark. The leaves are broadly heart-shaped, with coarse, blunt teeth, light green in color, smooth above and below or sometimes slightly hairy on the veins below. The large, spherical, black or greenish-yellow berries are in small loose clusters. It grows wild from southern Delaware to Missouri, Texas, and the Gulf States. The varieties of this species are known as Muscadine grapes. One of the chief varieties is the Scuppernong. Vitis rupestris (Sand Grape). — This is a low shrub with small, broadly beart-shaped, slightly lobed leaves with coarsely toothed margins. The small, black or purple-black berries are in small clusters. This species is southern in its distribution, reaching southern Pennsylvania as its northernmost limit. It is very resistant to rot and mildew of the foliage. Vitis riparia (River-bank Grape). — The river-bank grape is a rather vigorous climbing plant with smooth and slender twigs. The leaves have large stipules; the margin has sharp teeth that vary in size. The berries are small, black, coated with a bloom, and occur in rather compact, but small clusters. This is the most widely distributed and the hardiest of American grapes. It is common on stream banks in the United States east of the Rocky Mountains. Vitis aestivalis (Summer Grape). — This is a strong-growing species with leaves that are short-stipulate, thick, three- to five-lobed, shallowly dentate, dark green above and rusty pubescent beneath. The berries are astringent, of average size, and usually in long clusters. This species is native to southeastern United States. Its varieties are wine grapes. Vitis labrusca (Northern Fox Grape). — This is a stocky plant with large, heart-shaped leaves which are either entire or three-lobed, dark green above, and densely pubescent below. The clusters of thick-skinned berries are medium to large. VITACEiE 501 By far the greatest number of cultivated grapes are varie- ties of this species, or hybrids from it and other species, chiefly Vilis vinifera, the Old-World grape. Varieties of Table Grapes. — There are four very common varieties of table grapes: 1. Caiawba, hybrid of V. labrusca and V. vinifera. 2. Delaware, hybrid of V. labrusca and V. bourguiniana. 3. Niagara, hybrid of V. labrusca and V. vinifera. 4. Concord, variety of V. labrusca. Color of Grapes.^ — Varieties of grapes may be grouped as to color as follows: 1. Berries Purplish-black to Black. — America, August Giant, Bacchus, Black Hamburg, Canada, Champion, Concord, Ives, Mills, Muscat, Hamburg, Norton. 2. Berries Purplish-red. — Agawam, Brighton, Catawba, Delaware, Diana, lona, Jefiferson, Lutie, Massasoit, Red Eagle, Rochester, Vergennes. 3. Berries Light Green. — Colerain, Croton, Diamond, Duchess, Elvira, Grein Golden, Lady, Niagara, Triumph. Wine and Raisin Grapes.— As has been indicated, the European grape is a wine and raisin grape. Some varieties such as Petite Sirah, Beclan, Mondeuse, Verdot, Lagrain, Refosco, etc., are adapted to the manufacture of dry, white wines; Grenache, Mission, Palomino, and Boal, are a few varieties from which sweet wine is made; while some common raisin grapes are White Muscat of Alexandria, Malaga, and Sultanina. JJsQS.— Dried Grapes. — These are known under the names "raisins," ''Sultanas," and "English," "Corinth" or "Zanta currants." Thin-skinned varieties, such as Vinifera grapes, whose seeds do not adhere to the pulp, are preferable for raisins. "Sultanas" are small hght-colored raisins made 502 BOTANY OF CROP PLANTS from a small, seedless grape. ''English, "Corinth" or ''Zanta currants" are small dried grapes, grown chiefly in the south of Greece. Table raisins are made from the most select grapes, and usually dried in the sun, without pre- liminary dipping. The lower grades of grapes that are made into raisins for cooking purposes are nearly always dipped in weak lye before thy are dried. California produces almost all the raisins of the United States. According to the census of 1910 the production of raisins and dried grapes in the United States amounted to 169,245,100 pounds, of which California furnished 169,210,675 pounds. Wines. — There are two well-known sorts of wines: (i) dry wines, and (2) sweet wines. Dry wines are those in which the grape sugar has been converted into alcohol through fermentation. Sweet wines are those in which the grape sugar has not been converted into alcohol, but the process of fermentation has been prevented by adding alcohol. There are two groups of dry wines: (i) red wines (clarets, Burgundies, etc.); and (2) white wines (Hocks, Rieslings, etc.). Red wines are made from colored grapes, the skins usually furnishing the coloring matter for the fer- menting juice. In the making of red wines, the skins and pulp are crushed and placed in fermenting vats. The un- fermented grape juice is termed "must." Fermentation is brought about by the activity of yeast plants, and in this process, the conversion of sugar to alcohol takes place. After the completion of fermentation, the wine is drained from the pomace (skins and other solid material of the grape) and stored in various sorts of receptacles. A slow fermenta- tion goes on in storage, and during this period, settlings accumulate, which are finally removed, leaving the clear wine product. White wines are made from white grapes, or from those VITACEiE 503 colored grapes with a colorless juice. The coloring matter in the skin is not permitted to get into the juice, as the skins are removed by pressing, and the juice allowed to ferment alone. The two chief sweet wines in this country are the ports and angehcas. Port wines are made from colored grapes. The fruit is crushed and allowed to ferment; however, the process of fermentation is not allowed to proceed far, but is stopped by the addition of alcohol. This adding of alcohol to stop the fermentation process is called ''fortify- ing." In the making of angehca wines, the grapes are crushed, pressed immediately to remove the pomace, and the juice permitted to ferment until the desired degree of sweetness is attained, and then the process of fermentation stopped by "fortifying." Brandy. — Brandies are made both from white wines and red wines. Pure "cognac" is obtained from the distillation of French white wine. The inferior grades of brandy come from the distillation of inferior sorts of wine. Vinegar. — Grape vinegar is made from white and red wines, giving white and red vinegars respectively. Many grapes unsuited for drying, shipping, or wine-making can be turned into excellent vinegars. Other Uses.^ — Grapes are a common fresh dessert. The unfermented juice is sold in large quantities in bottles. A good table syrup can be made from some varieties. The wood is sometimes used in the manufacture of baskets, furniture, and rustic work. The plants are ornamental and are frequently turned into arbors. There are a number of by-products from the grape plant. Brandy, feed, fertil- izers, and acetic acid are made from the pomace. Tartaric acid is manufactured from the stems, shells and the "lees" of wine. The seeds are used as a food for stock and as a source 504 BOTANY OF CROP PLANTS of tannin and grape oil. A brandy has been made by fer- menting the sugary substance that sticks to the seeds, and this material may also be made into a syrup. References Beach, S. A.: Notes on Self-pollination of the Grape. N. Y. State Agr. Exp. Sta. Ann. Rept. 11: 597-606, 1892. Self -fertility of the Grape. N. Y. State Agr. Exp. Sta. Bull. 157: 397-441, 1898. Fertilizing Self-sterile Grapes. N. Y. State Agr. Exp. Sta. Bull. 169: 331-371, 1899- Booth, N. O.: A Study of Grape Pollen. N. Y. Agr. Exp. Sta. Bull. 224: 291-302, 1902. DoRSEY, M. J.: Variation Studies of the Venation Angles and Leaf Dimen- sions in Vitis. Am. Breeders' Assn., 7: 227-250, 191 1. Variation in the Floral Structure of Vitis. Bui. Torrey Bot. Club, 39: 37- 52, 1912. Pollen Development in Vitis with Special Reference to Sterility. Minn. Agr. Exp. Sta. Bull. 144: 1-60, 1914. Pollen Sterility in Grapes. Jour. Hered., 6: 243-249, 1915. Hedrick, V. P.: The Grapes of New York. 15th Ann. Rept. N. Y. Agr. Exp. Sta., vol. 3, part 2: 1-564, 1908. HusMANN, George C., and Dearing, Charles: The Muscadine Grapes. U. S. Dept. Agr. Bur. Plant Ind. Bull. 273: 1-64, 1913. MuNSON, T. v.: Investigation and Improvement of American Grapes. Texas Agr. Exp. Sta. Bull. 56: 217-285, 1899. Rabak, Frank: The Utilization of Waste Raisin Seeds. U. S. Dept. Agr., Bur. Plant Indus. Bull. 276: 1-36, 1913. Reimer, F. C, and Detjen, L. R.: Self-sterility of the Scuppernong and Other Muscadine Grapes. N. C. Agr. Exp. Sta. Bull. 209: 1-23, 1910. CHAPTER XXXIII MALVACEAE (Mallow Family) Habit. — Members of the family are herbs, shrubs, or trees. Tree species are tropical. The mallows are usually rich in mucilage. involucral bract \ \ \ca\\ik ^monade\phou>5 3tdmen6 Fig. 211. — Diagram showing arrangement of parts in the cotton flower. (After Cook. U. S. Depl. Agri.) Leaves.— The leaves are alternate, and mostly palmately veined and palmately lobed. The stipules are small, narrow, and deciduous. 505 5o6 BOTANY OF CROP PLANTS Flowers.^ — The flowers are either single or in clusters, and are terminal or axillary. Some are subtended by an involu- cel which resembles the epicalyx of strawberries. This involucre (Fig. 211) consists of three or more bractlets, which may be separate or united. In the marsh mallow {Althcea), the involucre consists of six to nine bractlets united at the Fig. 212. — Upland cotton (Gossypium hirsutum). Median lengthwise section of flower. X 2. base; in Abutilon, there is none; in Hibiscus, it is of numerous narrow bractlets; and in cotton {Gossypium), there are three large heart-shaped bractlets (Fig. 211). The flowers are regular (Fig. 212), perfect, often large, rarely dioecious or polygamous. There are five sepals (rarely three or four). MALVACE^ 507 more or less united, the lobes valvate or rarely imbricate. There are five petals, slightly united at the base, convolute in the bud, and often contorted. The stamens are character- istic features of the family. They are numerous, and united to form a long tube enclosing the styles; the staminal tube is united with the bases of the petals (Fig. 212). There are live more or less distinct projections at the top of the tube of stamens; this seems to indicate that there are in reality but five stamens, united by their filaments, and branched above into numerous stalks bearing pollen sacs. This is further evidenced by the fact that each stalk bears a single pollen sac, a structure equivalent to one-half of a typical anther. The stamen tube may be anther-bearing at the summit, as in Malva, Abutilon, etc., or anther-bearing below the summit, as in Hibiscus and Gossypium. The ovary is several-celled. Usually, there are as many styles as cells of the ovary; the styles are united below, and distinct above, and generally project beyond the stamen column. Fruit and Seeds. — The fruit is a several-celled capsule (rarely a berry). The seeds are kidney-shaped, globose or obovoid, and have large cotyledons and either little or abundant endosperm. Geographical. — Members of the family are widely distributed in tropical and temperate regions. There are about 40 genera and 800 species. Economic Importance.^ — The mallow family possesses one of our most valuable economic plants — cotton (Gossypium). Cotton is the chief fiber plant of the world. It is grown throughout tropical and subtropical regions. Another crop plant is okra or gumbo {Hibiscus esculentus). Althcea officinalis is the marsh mallow, the roots of which are used principally for mucilage and for medicinal purposes. Orna- mental representatives are hollyhock (Althcea rosea), mallow 5o8 . BOTANY OF CROV PLANTS {Malva spp.), poppy mallow {Callirhoe spp.), Abutilon and Hibiscus. The Rose of Sharon is Hibiscus syriacus. Key to Important Genera of Malvace^ Stamen column anther-bearing at the summit. Carpels one-seeded. Involucre of six to nine bractlets, Althaa (marsh mallow and holly- hock). Involucre of one to three bractlets, or none. Petals notched at the apex, Malva (mallow). Petals erose at the apex, Callirhoe (poppy mallow). Carpels two- to several-seeded, Abutilon. Stamen column anther-bearing below the summit (Fig. 212). Bractlets of involucre, numerous, Hibiscus. Bractlets of involucre, three, Gossypium (cotton). GOSSYPIUM (Cotton) Habit of Plants, and Roots.^ — There are more than 40 species of Gossypium, all of which are perennial in their native home. There are herbaceous, shrubby, and tree- like species. In cultivation, the plants are annual or biennial, and herbaceous. There is a long, branching, and deeply penetrating tap root. This extends to a depth of 2 feet or more in sandy soil. There are four rows of lateral roots from four shallow grooves that run lengthwise on the main root. The lateral roots are only a few inches below the soil surface. Stems.- — The main stems are erect and branching. The usual height of Upland cotton plants is sj-^ to 4 feet. The branches may be slender or stocky and are usually spreading. Kinds of Branches. — There are two sorts of branches in the cotton plant: (i) Vegetative branches or "limbs," and (2) fruiting branches. There are two buds at the base of each leaf. One of these is a true axillary bud, the other one, extra-axillary. Vegetative branches or Hmbs may arise MALVACE^ 509 from either axillary or extra-axillary buds. Normal fruit- ing branches arise only from extra-axillary buds. It fre- quently happens that both a fruiting and a vegetative branch arise at one node, that is, both the extra-axillary and true axillary buds develop. Ordinarily, however, only one bud at a node develops. The axillary buds usually develop into Fig. 213. — Upland cotton (Gossypium hirsutum). A, mature boll opened out; B, cross-section of young boll; C, single seed with fibers; D, young boll. branches at only a few nodes on the lower part of the main stem. The accompanying extra-laterals remain dormant. On the other hand, the upper true axillary buds normally fail to develop, while each of their accompanying extra- laterals forms a fruiting branch. Hence, in most cultivated cotton varieties, no fruiting branches occur on the lower part of the main stem. 5IO BOTANY OF CROP PLANTS In Upland varieties the fourth or fifth node is the first at which fruiting branches are produced; in Egyptian cotton, the first fruiting branches are produced from the eighth to the fourteenth nodes. Vegetative and fruiting branches dift'er from each other in other ways than origin. The former make a small angle with the stem from which they arise, while fruiting branches are more horizontal. Vegetative branches produce no flower buds, while fruiting branches bear a flower bud opposite each leaf. Vegetative branches are frequently as long as the main axis, while fruiting branches are much shorter. The basal internode of fruiting branches is usually longer than the others. The difference in length is much more pro- nounced in Egyptian cotton than in Upland cotton. The internodes of vegetative branches are about equal in length. Vegetative branches may form both fruiting and secondary vegetative branches, but fruiting branches seldom bear secondary fruiting branches or vegetative branches. Cottons with short-jointed fruiting branches are more productive and usually earlier than those with fewer and longer internodes. Form of Plant. — The general form of the cotton plant is determined to a large extent by the length and number of vegetative branches, as well as by the angle they make with the main axis. The plant may consist of a single stalk with a number of fruiting branches but no vegetative branches. An excessive development of lower vegetative branches makes a bushy plant. Branch Zones. — The cotton plant frequently has three branch zones. This condition, described by McLachlan, is pronounced in Egyptian cotton. The zone of vegetative branches extends from the third to the tenth node; this is followed by a "transition zone" or "zone of rudimentary branches," of two or three nodes "at which the buds remain MALVACE^. 511 dormant, or the branches are extremely short or abortive." The "zone of fruiting branches follows from about the thirteenth node to the tip of the plant. " Underground Stems. — The cotton plant may produce underground stems. These arise from the same grooves from which lateral roots come. At first, these subterranean shoots are gall-like. Later, they attain various sizes. Leaves. — The leaves have a regular spiral arrangement. The most common phyllotaxy in the cotton plant is three- eighths. This is the normal arrangement in all pure strains of Upland and Sea Island species and other natives of tropical America that are related. It is pointed out that with "the advance of acclimatization, the leaf arrangements are varied by frequent examples of one-third and two-fifths spirals" . . . Egyptian-Upland hybrid plants may have a one-third, two-fifths, or five-thirteenths arrangement. The phyllo- taxy is one-third in Asiatic cottons. 'However, when Asiatic species are crossed, the hybrid plants may show a two-fifths or three-eighths arrangement. Leaf arrangement is similar on main stem and vegetative branches, but on fruiting branches the leaves are in two alternate rows; this latter condition is brought about by a twisting of the joints, each internode being twisted in the opposite direction from the adjacent. The leaves are petioled, stipulate, cordate as a rule, and three- to seven-lobed, sometimes nine-lobed. Glands may be present or absent on the leaves. When present, they occur on the under side of the main ribs, about one-third of the distance from the bases. The leaves on fruiting branches are often irregular in outline and may have one or two glands. The leaves on vegetative branches and on the main stem are regular in outline, and have nectaries on the midrib and occasionally on the principal 512 BOTANY Oi' CROP PLANTS veins on the underside. Three to six inches is the common length of Upland cotton leaves. Flowers. — Flower buds arise on fruiting branches. They do not arise in the very axil of a leaf, but are distant from it. There is a flower opposite a leaf at each node. There is one flower in each bud. The flowers of Asiatic species are often pendant. Upland cotton flowers are 3 to 4 inches across, white when they first open but turning pink on the second day. Sea Island cotton flowers are usually yellow, with a purple-red spot at the base of each petal. Involucre. — Each flower is subtended by an involucre (Fig. 211) composed of three bracts (sometimes four in cultivation) united at the base. They are frequently large, dentate or laciniate, sometimes entire. One of the bracts is often some- what smaller than the other two which are equal in size. In some cases bractlets may occur inside the involucre. They alternate with the bracts. When two are present they stand on either side of the smaller bract. This is the case in Upland varieties in the United States. In certain Central American varieties, they are sometimes six bractlets, a pair alternating with each of the three bracts. Nectaries. — At the base of the outer surface of the bracts are nectaries, in American sorts, but they are absent in all cultivated Asiatic cottons. There are also inner involucral glands in both American and Asiatic varieties. In the former, these inner involucral glands are naked, with excep- tion of Guatemalan cotton, while in Asiatic cottons they are protected by a velvety covering of hairs. Calyx.- — This is a very short, cup-shaped structure at the base of the corolla. The rim of the cup is usually five-lobed, the lobes being short and broad, or sometimes rather long and pointed. In Egyptian cotton and some Asi- atic species, the rim of the calyx is frequently very even, MALVACE^ 513 scarcely lobed. The calyx lobes often vary in size. There may be two large lobes, two small ones, and one intermediate in size. Floral nectaries appear at the base of the calyx on the inner side. " Intracalicary Organs.^' — These sometimes occur in the cotton flower. They are a series of small greenish organs between the calyx and corolla. There are five of these structures, but often some of them are so small as to be visible only by use of the hand lens. They are attached to the calyx, and alternate with its lobes. Cook and Meade regard them as "supernumerary calyx lobes or as representing free stipular elements of the calyx lobes." Corolla. — This is hypogynous. There are five petals, often united at the base, and attached to the lower part of the stamen tube. They are usually yellow or red in color. In G. harbadense the petals are yellow or sulphur-colored, with a purple spot on the, claw. The petals are convolute in the bud. Stamens. — These are monodelphous in cotton. There are often as many as 80 or 90 stamens, all inserted on a tubular staminal column, which encloses the pistil. The column is dilated at the base and narrowed above. There are five vertical ridges on the staminal column, each of which gives rise to a number of filaments. The column is regarded as being made up of the united filaments of the stamens. The filaments are thread-like and exserted. The anthers are one- celled, and each is dehiscent into two halves, by a semicircular opening. Ovary (Fig. 213). — This has three to five cells or "locks." As a rule, the style is long, thus bringing the stigmas above the stamens. In Upland varieties, however, the style is usually shorter than the stamens. There are as many stigmas as there are cells in the ovary. S3 514 BOTANY OF CROP PLANTS Pollination, Fertilization, and Development of Fruit.^ — Both cross- and self-fertilization may occur in cotton. Bees may be necessary in those varieties in which the style is long and brings the stigmas above the anthers. Floral nectaries, at the base of the calyx on the inner side, are reached from within the corolla by long-tongued bees and butterflies. This is enabled by the failure of the petals to overlap at the base, thus leaving gaps through which the insect may protrude its tongue. In Mississippi the period required for maturity of bolls is from forty-four to forty-six days. The seeds retain their attachment to the placenta until lint begins to develop, when their connection is broken through the absorption of the seed stalk, and the mechanical pressure of growing lint. Hence, the seeds come to occupy a position in the center of the cavity. Fiber begins to develop first at the apex of the seed. Fruit. — The cotton fruit (Fig. 213) is a leathery capsule loculicidally dehiscent by three to five valves. The mature capsule is called a "boll." It varies in shape: subglobose, oval, or ovate-acuminate. The number of cells or ''locks" is three or four in Sea Island and Egyptian varieties, and four or five in Upland sorts. Seeds. — There are numerous seeds in each "boll." Seeds vary in shape: subglobose, ovate, or subovate. Fiber. — The cotton fiber or hair is a simple extension of an epidermal cell of the seed coat. As a rule, there are two kinds of hairs on the seed: (i) long hairs — lint or commercial fiber ("staple") and (2) short hairs or fuzz. The fuzz may be white, green, or brown in color. Some varieties produce no fuzz; hence when the seed is "ginned," it is left naked. Fuzzy-seeded varieties usually possess an abundance of long fibers. A high percentage of lint usually indicates small MALVACE^ 515 seed. In some varieties, the lint may form 34 per cent, or more of the seed. Distribution of Seed Hairs.— Lint and fuzz are mixed to- gether over the entire seed surface in Upland cottons. In Egyptian sorts, fuzz is limited to the ends of the seeds, with long libers between the two patches. The lint at the tip of the seed in some Upland cottons is longer than that at the base. Fiber Differences. — The fibers of Upland cotton are i to 2 centimeters long, and abundant; those of Sea Island are 2.5 to 4 centimeters long, but the yield is not as great as in the preceding species. The following table is taken from Monie: Average length of Average diameter staple in inches of staple in inches Sea Island 1.61 o. 000640 New Orleans 1.02 0.000775 Texas i . 00 o . 000763 Upland 0.93 0.000763 Egyptian 1.41 o. 000655 Form and Structure of Fiber. — Young cotton fibers are circular in cross-section. As they increase in length, the walls become thinner, and the fiber takes on a flattened rib- bon-like appearance. The thickness of the walls becomes greater when the boll opens, due to the rapid consolidation of the liquid cell contents, which become deposited on the inner walls. The deposition is irregular, hence the twisting of the fiber. This twisting is a characteristic of the cotton fiber. The twist is not necessarily in one direction through- out its length; there may be a reversal here and there. The fiber is uniform in diameter for about three-fourths of its length, and then tapers gradually to a point. At the point, it may be perfectly cyhndrical and solid. The hair cavity or lumen takes up about two-thirds of the entire 5l6 BOTANY OF CROP PLANTS breadth. Immature fibers or unripe fibers may show no evidence of internal structure, but are smooth, straight, and flat. "Kempy" fibers or "dead cotton" are such that are normal in structure a portion of their length, and have the appearance of immature and overripe fibers for another portion. The quality of fiber depends largely upon the number and regularity of twists, and upon its length and fineness. The mature cotton fiber is almost pure cellulose. Cotton Fibers Distinguished from Other Common Textile Fibers. — There are two chief ways of distinguishing textile fibers, by microscopical examina- tion and by chemical reactions. The cotton fiber is a flat, ribbon-like band twisted in a characteristic manner. The flax fiber is a straight, untwisted, cylindrical fiber, with peculiar transverse markings at intervals along its length. Hemp fibers resemble those of flax, but they may be distinguished from the latter by the peculiar forked ends which are nearly always exhibited, whereas flax fibers never show this character. All wool fibers possess char- acteristic overlapping scales. The silk fiber is smooth, structureless, trans- parent and quite regular in diameter. There are many ways of distinguishing the fibers by observing their reac- tions to various chemicals. The following short key will illustrate a few of their characteristic reactions. Dissolves in caustic potash. An alkali solution of the fiber treated with lead acetate colors fiber black, Wool. The above treatment does not color the fiber, Silk. Does not dissolve in caustic potash. With iodine and sulphuric acid the fiber swells and becomes green, Hemp. With iodine and sulphuric acid the fiber swells and becomes blue. Immerse fiber in concentrated sulphuric acid for two minutes, wash in water, treat with dilute ammonia, dry — fiber forms a gelatinous mass soluble in water. Cotton. With above treatment, fiber is not altered, Linen. Species.^ — Watt, in his great work, describes 42 distinct species and varie- ties of Gossypium. A number of them are known only in the wild state. Gossypium, as a genus, is indigenous to tropical regions. It is now grown under culti station to the 40° latitude on either side of the equator. Watt divides the wild and cultivated cotton plants of the world into five "sections," as follows: MALVACE^ 517 Section I. Species with a Fuzz but no Floss. — "Wild species (never recorded lis met with under cultivation), distributed from the western coast tracts and islands of America to Australia." Here are included G. sturtii, davidsonii, klolzschianum, robinsoni, darwinii, tomentosum, drynarioides, harknessii, and stocksii. The bracteoles are free, extrafloral nectaries absent, the fruit small, and the rather large seeds have a fuzz but no lint. Section II. Fuzzy-seeded Cottons with United Bracteoles. — "One or perhaps two members of this section have been recorded as met with in a wild condi- tion, the others are undoubted cultivated plants derived very possibly from four specific types — G. arboreum, G. nanking, G. obtusifolium, and G. herba- ceum." Most of these are Asiatic and African cottons. The bracteoles are united below, the claws of the petals are purple, and the seeds are covered with both fuzz and lint. Watt is strongly of the opinion that G. arboreum var. neglecta, was at an early date introduced into the United States, the form being known as "Okra." Its cultivation was abandoned, however. G. nanking is the "Chinese cotton" of commerce, also known as "Siam cotton" or "Nankin cotton." It is "cultivated in China, Japan, the Malaya, Siam, Burma, India, the northwest Himalaya, Persia, Central Asia, to the Celebes; less abundantly in Madagascar, Arabia, and Africa." G. obtusifolium is an oriental species that occurs both wild and cultivated in India and Africa. Var. wightiana is the most valuable Indian cotton. G. hcrbaceum is not known to occur as a wild species anywhere, although Watt is of the opinion that it is indigenous to North Arabia and Asia Minor. In 1621, it was brought to the United States, and for a time cultivated, but was finally replaced by the more desirable West Indian cottons. G. herbacenm is considered to be the first cotton cultivated in Europe. Watt belie v^es that it still survives as an Upland cotton of the United States, though "mostly in a state of hybridization with G. hirsutum." Cook regards our Upland cot- tons as belonging to G. hirsutum. Section III. Fuzzy-seeded Cottons ivith Free Bracteoles. — These are Ameri- can and, in one case, African species. Here belong G. mustelinum , punctatum, hirsutum, palmerii, fruticulosum, schottii, lanceolatum, microcarpum, peruvi- anum, and mcvicanum. G. mustelinum is a native of Brazil and Colombia. G. punctatum is native to southern United States, West Indies, and northern Africa. It exists in a state of cultivation in various sections. Watt considers G. hirsutum as "only a cultivated state of G. punctatum" ... In this country, however, the Upland cottons are all considered as ofi'springs of hirsutum (Fig. 214). G. palmerii, fruticulosum and lanceolatum are Me.Kican species. G. schottii is from Yucatan, and is known as the "split-leaved" cot- ton. G: microcarpum, known as Ashmouni cotton and Red Peruvian cotton, grows in Mexico, northern South .Vmerica, Africa, and Malaya. It is culti- vated. G. peruvianum is the Peru\ian or Andes cotton. Watt regards many of the Egyptian cottons as races or hybrids of this species. G. mexicanum 5i8 BOTANY or CROP PLANTS probably originally came from Mexico. Watt says: "I am convinced that the best Upland cottons would be more correctly described as cultivated states of this plant (G. mexicaniifn) , rather than as forms of G. hirsutum." He con- siders many of our Upland or short staple cottons as hybrids of G. mexicanum and G. hirsutum, sometimes with the characters of the one predominating, sometimes with those of the other. The long staple Upland series, chief Fig. 214. — American upland cotton (Gossypium hirsutum). (After Watt.) representatives of which are Allen, Peeler, Simms and Sunflower, are also hybrids, with hirsutum. characters dominant. Section IV. Naked-seeded Cottons with the Bracteoks Free or Nearly so and Glands Conspicuous. — This section includes both Old- and New- World forms. The seeds are naked or nearly so, and the lint is easily removed. There is always some fuzz on the seed at the apex, hence they are not absolutely MALVACEAE 519 "naked." To this section belong G. tailciisc, purpiiraiccns, vilijoliiiin, bar- badensc, and brasiliense. G. tailense is the wild cotton of Polynesia. It is not cultivated. G. pur- purascens is known as Bourbon, Porto Rico, and Siam cotton. It is an im- portant cultivated species. G. vitifoUnm, the vine-leaved cotton, has fur- FiG. 215. — Sea Island cotton (Gossypium barbadense). {After Walt.) nished a number of valuable cultivated types in Egypt, Antilles, etc. It is closely related to G. barbadense. G. barbadense (Fig. 215) includes the Sea island cottons of America and Egypt. Watt believes that Sea Island cotton is a modern development, not indigenous to Barbados or any of the West Indian Islands, but probably from somewhere in South America. He says 520 BOTANY OF CROP PLANTS that "it is highly probable the modern stock is a hybrid." The Sea Island cottons proper which have been grown with the greatest success on the islands off the coast of Carolina and Georgia are referred to G. barbadense var. marilima. G. brasiliense is indigenous to South America. It is cultivated extensively and is known as "Chain, Kidney, Stone, Brazilian, Guiana, Esse- quibo, Berbiche, Bahia, Pernambuco, and Coton-pierre cottons." This group is no longer of great commercial importance. Section V. Naked-seeded Cotton with Bracteolcs quite Free and Floral Glands Absent. — Only one species, G. kirkii, belongs to this. It is from East and Central Africa, and is not cultivated. The lint is easily removed from the seed. Wild Cottons. — Wild cottons all have a red-colored, hairy coating on the testa. As is seen above, there may be fuzz only, or both fuzz and lint, or lint alone. Cultivated cottons have a long white lint, in both fuzzy-seeded and naked-seeded forms. Sea Island cottons have the least fuzz of all culti- vated forms. White lint may be regarded as brought about by cultivation. The appearance of rust-colored fuzz or lint may be regarded as a tendency to revert to the ancestral type. The reddish tint of wild cottons is due to an aggregation of colored particles in the central core of the fiber. American Cottons.- — American authorities place the cot- tons of the United States into two species: G. hirsutum, American Upland cotton, and G. barbadense, Sea Island, cotton. It has been noted above, however, that Watt claims that our Upland cottons are hybrids between G. hirsutum and G. mexicanum. Ninety-nine per cent, of the cotton crop in the United States is Upland. The most important distinction between these two species is in staple length. The fibers of Upland cotton are from i to 2 centimeters long, those of Sea Island 2.5 to 4 centimeters long. The yield of the former is greater but the quality not so fine. The flowers are white, turning red on the second day of blooming in Upland cotton, but yellow with a purple-red MALVACE^ 521 spot at the base of each petal in Sea Island cotton. The latter is limited to a small area along the coast of South Carohna, Georgia, and Florida. Types and Varieties. — Upland is the chief American cotton. It has been divided by Duggar into a number of "groups" as follows: 1. Big Boll Group. — Plants vigorous and stocky; limbs strong, usually two in number; fruiting branches strong, varying from short to long; bolls large, 45 to 68 of them yielding a pound of cotton; four to five locules; seeds large, very fuzzy, white to brownish gray or greenish in color; lint 20 to 30 milli- meters long. Examples: Russell, Truitt, Truimple, Texas Storm-proof, and Jones Improved. 2. Long Staple Group. — Plants slender; limbs two or three, sometimes ab- sent, slender; fruiting branches also slender; bolls small to medium, long, slender, tapering to a point, three-, four-, or five-loculed; seeds medium to large, sometimes partly naked, but usually densely covered \vith a brownish- gray fuzz; lint 30 to 45 millimeters long, percentage low. Examples: Allen, Griffin, and Cook. 3. Cluster Group. — Plants slender, often tall, limbs heavy, one to several; fruiting branches very short-Jointed, causing the bolls and leaves to be in clusters, apparently two or three from each node; bolls small to medium, four- to five-loculed; seeds small to medium, fuzzy, gray to brownish- or greenish gray; lint short, soft, and of good strength. Examples: Jackson, Dickson. 4. Semi-cluster Group. — This group resembles closely the preceding. The bolls are borne singly but close together. It is probably a hybrid group with strong cluster tendencies. Examples: Peerless, Defiance, Bernett, Berryhill, Hawkins. 5. Rio Grande or Pelerkin Group. — Plants slender; limbs one to several; fruiting branches slender, long-jointed; bolls very small to medium, three-, four-, or five-loculed; seeds very small to medium, nearly smooth, dark- colored, sometimes covered with a short fuzz; lint medium in length, percent- age large. Examples: Peterkin, Texas Wood, Rio Grande. 6. King or Early Group. — Plants small and slender; limbs one to three or more; fruiting branches medium to short-jointed, but long in proportion to plant height; bolls small, three-, four-, or five-locked; seeds small to medium, fuzzy, greenish or brownish gray; lint short to medium, ^^ to 35 per cent, of seed. Earliest American cottons. E.xamples: King, Dozier, Hodge, Mascot. 7. Long-limbed Group. — Plants large; limbs long with long joints; bolls and seeds medium to large; lint percentage low; fuzz of various shades. Exam- ples: Petit Gulf, Peeler, Hagaman. This group is of little importance. 8. Intermediate Group. — This group includes a number of varieties with 52 2 BOTANY OF CROP PLANTS characters so badly mixed up as to make it impossible to refer them to any particular group. It is well known that our American cottons hybridize quite readily under field conditions. Examples: Breeden, Boyd, Roby, Tucker. Environmental Relations.^ — Cotton is a tropical plant. The upper latitudinal limit of cotton growing in this country is about coextensive with the summer (June, July and Au- gust) isotherm 77°F. The plant is extremely sensitive to low temperatures, and even a light frost in the fall stops its development. It seldom matures in less than i8o days. The plant not only requires a high temperature, but also one not subject to fluctuations, as such conditions cause premature ripening. After the plant has attained its vege- tative growth, the ripening of fruits and seeds is favored by cooler nights than prevailed up to that period. Light, frequent showers which permit of an abundance of sunshine favor the development of the plant. Too much rain is liable to stimulate an excessive development of vege- tative growth at the expense of fruit formation. Upland cottons are adapted to a variety of soils, while the Sea Island varieties are best suited to soils with low water- retaining capacity, and of medium fertility. Picking and Ginning of Cotton. — Cotton is picked by hand, and loaded into wagons. This labor is performed almost exclusively by negroes. The seed cotton is removed from the wagon by means of a suction fan, and carried over a single gin or battery of gins. It passes into chutes over the feeders, and is then fed evenly to the gin saws, where the lint and seed are separated. The seeds are carried by a screw conveyor to the seed house or seed bin. The lint cotton is led from the gin saws through a flue to the condenser. Here it is cleaned, smoothed out into sheets or bats, wrapped and tied into bales. The usual size of a cotton bale is 27 by 54 inches and the weight about 500 pounds. Sea Island cotton is ginned MALVACEAE 523 in a type known as the roller gin, as the fiber is injured by the saw gin type. When seed cotton comes to the gin, it contains boll hulls and trash. This is usually removed by passing the seed cotton through a cleaner, before it reaches the gin saws. The boll hulls are frequently used for fuel. Bleaching of Cotton.— The object of this process is to remove the waxy coating of the fiber, in order that it may absorb the dyestuffs easily, and also remove all the impurities adhering to the fiber. Cotton may be bleached in any stage of its manufacture, in the loose state, as yarn, or as cloth. The process of bleaching is the most thorough and is carried further in the making of print cloth than in the preparation of other grades of cloth, as the cloth must be absolutely white and free of all impurities in order that the printing colors can be applied properly, and the patterns appear distinct and sharp. The cloth is first singed to remove -loose fibers and lint, and leave a clear even surface. It is then taken through the boiling out process, in which the cloth is given one or more boihngs in caustic soda in order to remove the waxy, fatty and pectic substances from the fiber. After a thorough was/ling in water, the cloth is treated with a bleaching powder solution. The souring process follows, in which the cloth by treatment with a dilute solution of sulphuric acid is rendered free of the lime compounds and undecomposed chlorine derivatives. Another thorough washing then follows, after which the cloth is given a finish, the nature of which depends upon the use to which it will be put. Uses of Cotton. — The lint is spun into thread or yarn, and woven into all sorts of fabrics. The finer threads are made from Sea Island cotton, while ordinary threads and yarns are from long staple upland cotton. The short lint or fuzz, 524 BOTANY OF CROP PLANTS known as "linters/' which is not removed in ginning, is taken from the seeds and made into coarse twine, carpets, and batting. Cottonseed Hulls. — These are used in the manufacture of paper and fiber board from which are made gear wheels, trunks, etc. The hulls are also utilized as fuel and fertilizer, and as a cattle food. Cottonseed Oil.- — This is one of the most valuable products of the cotton plant. The oil of the seed is in the embryo. After the seed coats are removed, the embryos ("meats"), are cooked for twenty to thirty minutes to melt the oil, and to drive off some of the water. The oil is then extracted under pressure. A ton of seed yields about 40 gallons of crude oil. Various grades of cottonseed oil are secured by different processes of refining and filtering. Cottonseed oil is now produced in large quantities in this country. The United States exported 35,304,000 gallons of the oil in 1 91 3. It is used for edible purposes, appearing on the market usually under some such name as "sweet nut oil," "salad oil," or "table oil." It may be utilized as an adulterant of such oils as peanut and olive oils. However, it is fully as nutritive as olive oil and is actually preferred by many. It is used sometimes in the manufacture of soaps. It is also extensively employed in the manufacture of "oleo- margarine," and butter and lard substitutes. "Cottolene" is composed of refined cottonseed oil and beef suet. Cottonseed Meal. — Cottonseed meal is the ground cake left after the oil is pressed from cotton seed. It is now used extensively as a feed, although formerly it was considered of little value. United States produces annually about 2,000,000 tons of cottonseed meal, valued at about $53,000,- 000. The death of animals sometimes associated with its use is due to a toxic substance, gossypd. Cottonseed MALVACE^ 525 kernels are now rendered less toxic by extracting the gossypol with ether, or with ether and alcohol; or by treating the meal with an alcoholic solution of an alkali, thus oxidizing the gossypol and rendering it non-toxic. Cottonseed meal is also highly prized as a fertilizer. GuncoUon. — This is a powerful explosive made by treating 526 BOTANY OF CROP PLANTS cotton or some other form of cellulose with nitric acid or sulphuric acid. MiKtary guncotton is a mixture of very highly nitrated cellulose nitrates. Less highly nitrated guncotton is soluble in alcohol and ether, and such soluble guncotton is used in the manufacture of collodion, celluloid, etc. Celluloid is made by subjecting a mixture of guncotton, camphor, and other minor substances to great pressure. Collodion is a solution of guncotton in ether and alcohol. Fig. 217. — Cotton-producing regions of the United States. {From Essentials of Geography, Second Book. Copyright, 1916, hy Albert Perry Brigham and Charles T. McFarlane. American Book Company, Publishers.) Importance, and Production of Cotton.^Cotton is the most important fiber plant in the world. The clothing of a great majority of people is cotton. The largest of manufac- turing enterprises are concerned with the production of cotton goods. Cotton is the most important article of world trade. The world's crop in 1910 is estimated at 22,433,269 bales, as compared with 15,893,591 bales in 1900. In 1914, the United MALVACEiE 527 States led in cotton ])rocluction, with 16,134,930 bales. British India ranked second with an output of 4,238,494 bales. The following table gives the production of cotton by States, 1915. Production of Lint (Excluding Linters) in 500-pouND Gross Weight Bales, by States, 1915 State Bales Texas 3,175,000 Georgia i ,900,000 South Carolina 1,160,000 Alabama 1,050,000 Mississippi 940,000 Arkansas 785,000 North Carolina 708,000 Oklahoma 630,000 Louisiana 360,000 Tennessee 396,000 All other States 108,000 United States 11,161,000 Total value of crop $602,393,000 HIBISCUS ESCULENTUS (Okra, Gumbo) Description.- — Okra or gumbo is a stout, annual plant. The stems are cylindrical and usually rough-hairy. The leaves are large, heart-shaped, three- to five-lobed, and with very prominent veins; the lobes are coarsely toothed. The solitary, showy flowers arise in the leaf axils; they are subtended by numerous, narrow, involucral bracts; the calyx is five-cleft; there are five large yellow petals; the stamens form a column which is five-toothed at the apex, and is anther-bearing along its entire length; the ovary has five cells, each of which has several ovules; there are five style branches, each tipped by a capitate stigma. Okra is regu- larly cross-pollinated by insects, chiefly bumblebees. The fruit is a pod with five longitudinal ribs; the seeds are large and kidney-shaped. 528 BOTANY OF CROP PLANTS Geographical.— The original home of okra is Africa. It is now introduced into many civilized countries, and grown as a vegetable with particular suc- cess in the warmer ones. Types. — Beattie divides the varieties of okra into three types: (i) Tall green, (2) dwarf green, and (3) lady finger. Each of these is further divided into long-podded and short- podded sorts. Plants of the "lady-finger" type are much lighter in color than those of the other two types. Tall green okras are 4 to 8 feet high, dwarf green sorts about lYi to 3^^ feet high, and lady-finger varieties close to 3 feet high. Uses.^ — Okra is used chiefly in soups. Not infrequently the young seeds are cooked. When the pods are very young and tender, they are cooked and served as a salad. A fiber used in the manufacture of paper is sometimes made from both stems and mature pods. In some countries the pods are dried, and in this form kept for winter use. References Balls, W. L. : The Sexuality of Cotton. Yearbook Khediv. Agr. Soc. Cairo, 1905. Beattie, W. R.: Okra: Its Culture and Uses. U. S. Dept. Agr. Farmers' Bull. 232: 1-16, 1905. Bowman, F. H.: Structure of the Cotton Fiber. Manchester, England, 1881. Brooks, E.C.: The Story of Cotton. Chicago, New York, andLondon, 191 1. Cook, O. F., and Meade, R. M.: Arrangement of Parts in the Cotton Plant. U. S. Dept. Agr. Bur. Plant Ind. Bull. 222: 1-26, 1911. Dimorphic Leaves of Cotton and Allied Plants in Relation to Heredity. U. S. Dept. Agr. Bur. Plant Ind. Bull. 221: 1-59, 1911. Cook, O. F., McLachlan, Argyle, and Meade, R. M.: A Study of Diversity in Egyptian Cotton. U. S. Dept. Agr. Bur. Plant Ind. Bull. 156: 1-60, 1909. DuGGAR, J. F.: Descriptions and Classification of Varieties of American Upland Cotton. Ala. Agr. Exp. Sta. Bull. 140: 1-104, 1907. Evans, W. H.: Botany of Cotton. U. S. Dept. Agr. Office of Expt. Stats. Bull. 2>3'- 67-80, 1896. Contains a Bibliography of Cotton. Flatters, A.: The Cotton Plant: Its Development and Structure and^the Evolution and Structure of the Cotton Fiber. London and Manchester, 1906. MALVACE^, 529 IIIilZMANN, 11.: Die Hiiuinwullc. Zurich iiiid Lcipsic, 1913. Meade, R. M.: Methods of Securing Sclf-polHnation in C'oUon. U. S. Dept. Agr. Bur. Plant Ind. Cir. 121: 29: 30, 1913. MoNiE, Hugh: The Cotton Fiber, Its Structure, Etc. Manchester and London, 1890. Oppel, a.: Die BaumwoUe. Leipsic: Duncker und Humblot, 1902. Parlatore, Filippo: Le specie dei cotoni, 1866. Reed, E. L.: Leaf nectaries of gossypium. Bot. Gaz., 63: 229-231, 1917. Steuckart, C: Die BaumwoUe, ihre Herkunft, ihre Verwendung, ihre Ge- schichte, und Bedeutung. Leipsic, 1914. Tyler, F. J.: The Nectaries of Cotton. U. S. Dept. Agr. Bur. Plant Ind. Bull. 131: 45-54, 1908. Varieties of American Upland Cotton. U. S. Dept. Agr. Bur. Plant Ind. Bui. 163: 1-127, 1910. Watt, G.: The Wild and Cultivated Cotton Plants of the World. New York and London, 1Q07. 34 CHAPTER XXXIV UMBELLIFER^ (Carrot Family) Stems and Leaves. — All the common representatives of the carrot family are herbs. A very few are shrubs or trees. The stems are usually hollow. The leaves are alternate, sometimes opposite at the base of the stem, and as a rule pinnately or ternately compound. In a few genera (as Bupleurum, Hydrocotyle and Oxypolis), they are simple. In Sanicula, they are digitately parted or lobed. In the carrot, fennel, and others, the leaves are decompound. The petioles are frequently swollen and broadened at the base and partly sheathe the stem. There are no stipules, or, if present, are very small. Inflorescence and Flowers. — The inflorescence is nearly always an umbel, either simple or compound, but occasionally a head (as in Eryngium). The umbel is so characteristic of this group of plants as to suggest the name " UmbeUiferae " (Hterally meaning umbel-bearing). In a compound umbel, the smaller groups of flowers are designated umbellets. The umbel as a whole is commonly subtended by an involucre, the umbellets by an involucel (little involucre) . When the inflorescence has an involucre, it is said to be involucrate; when it has involucels, it is involucellate. The flowers (Fig. 218) are small, mostly regular, perfect or polygamous, and pentamerous. In some instances, the outer flowers of the umbiel are irregular, the petals pointing outward being somewhat larger than those pointing inward. The calyx, when present, forms a tube wholly adnate to the 530 UMBELLIFER^ 531 ovary; the limb of the tube is absent, or divided into five inconspicuous teeth. The corolla consists of five separate petals, attached to the base of the calyx tube; the tips of the petals are usually turned in, and emarginate or two-lobed. There are five stamens, curved inward in the young flower, with filiform filaments and versatile anthers. The single, -onther __ _ - ''^t\ilopodium :-'3lamen commisiural ^ide Fig. 218. — Parsnip (Pastinaca sativa). .4, median lengthwise section of flower, X 12; B, face view of same, X 12; C, dorsal view of single mericarp, X 2H; D, floral diagram; E, schizocarp with mericarps separating at maturity, X ■2y>; F, cross-section of single mericarp, X 10. (D after Slrashurger.) inferior ovary consists of two locules, with a single seed in each, and of two distinct, straight, filiform styles borne on a swollen nectariferous style foot, the stylopodium (Fig. 218). In some genera (as Apium, celery), the stylopodium is inconspicuous or wanting. The umbellifers are usually insect-pollinated. Protandry is common. 532 BOTANY OF CROP PLANTS Fruit. — 'J'he umbelliferous /rz/// (Fig. 218) is very charac- teristic. It is termed a schizocarp, i.e., a dry fruit of two carpels, these separating at maturity along the midline or commissure into two one-seeded halves — the mericarps. Each individual carpel or mericarp is indehiscent. The two mericarps remain attached for a while after splitting by a forked stalk, the carpophore (Fig. 218, E). At the summit of the fruit is a swollen nectary, the stylopodium, giving rise to two short, persistent, usually outwardly curved styles. Each mericarp bears, on the outside, live longitudinal mem- branous or corky ribs, the primary ribs. These are modifi- cations of the pericarp; each encloses vascular bundles. In some cases, there is one secondary rib in each of the four furrows or grooves between the primary ones, thus making in many instances nine ribs (five primary, four secondary) to each half of the mature fruit. Within the grooves, as is best seen by a cross-section of a mericarp (Fig. 218, F), are oil tubes (vittae), running lengthwise of the fruit. These tubes contain secretions of balsams, resins, and volatile oils, which impart to the fruit its characteristic odor and taste. The fruit may be bristly (as in carrot) or smooth (as in parsnip, and many others). The bristles may cover the fruit (as in Sanicula), or be confined to the ribs (as in carrot). Oil tubes are sometimes obsolete or obscure (as in Conium, Hydrocotyle, Washingtonia). If distinct, they are solitary (as in parsnip) or several (as in Angelica, Cymopterus). There are usually two or more oil tubes on the commissural side, that is, on the side that is contiguous with the adjoining mericarp. The fruit is either flattened laterally (at right angles to the commissure), or flattened dor sally (parallel to the commis- sure), or in some instances not flattened at all (terete or nearly so). The one seed in each carpel completely fills the I UMBELLIFER^ 533 whole cavity and is usually adnate to the pericarp; the inner seed faces may be concave or flat. There is considerable oily endosperm present in the seed. The small embryo is imbedded in the endosperm near the hilum. The fruit is of greater taxonomic importance than any other portion of the plant. Usually, it is necessary to have the mature fruit before an accurate determination can be made of a species in hand. Keys to the genera and species are largely based upon fruit characters. Geographical. — The carrot family is one of north temperate regions, not being well represented in the tropics. According to Britton and Brown, there are close to 1,600 species in about 170 genera. Key to Genera of Economic Import.vxce Fruit bristly, Daucus (carrot). Fruit not bristly. Fruit strongly flattened dorsally, with lateral ribs more or less prominently winged (Fig. 218, F), Paslinaca (parsnip). Fruit not strongly flattened dorsally, usually more or less laterally flattened (Fig. 222, B). Stylopodium conical. Involucre wanting; leaves pinnately compound. Flowers white, Coriander (coriander). Flowers yellow, Fcenkuhim (fennel). Involucre present; leaves ternately compound, Cariim (caraway). Stylopodium flat or wanting, Apium (celery and parsley). DAUCUS CAROTA (Carrot) Habit, Root and Stems.— The common carrot is usually a biennial, sometimes, however, running to seed the first year. During the lirst season of growth, there is a storage of food in the enlarged hypocotyl and prominent tap root, both of which become fleshy, forming the so-called "carrot." Four longi- tudinal rows of secondary roots are given off from the tap root. The roots are much thinner and woodier in the wild form of the carrot than in cultivated forms. 534 BOTANY OF CROP PLANTS 'pnmar\j nd^e In a cross-section of the "carrot" the following tissues may be seen, from the outside to inside: (i) periderm (skm) ; (2) cortex and phloem; (3) cambium; (4) central region (wood and pith) . A good carrot is one with a proportion- ately large cortex and phloem, because in these most of the sugar is stored. During the second season of growth, a rough, hispid stem, 2 or 3 feet high, and with spreading branches, is sent up from the "crown" of the carrot. Leaves. — All the leaves are decompound (doubly compound). The lower ones are two- to three- pinnate, the segments Hnear or lanceolate, den- tate, lobed or pinnatifid, the upper ones smaller and less divided. Inflorescence and Flowers.— The inflores- cence is a compound umbel. At maturity, the outermost pedicels bend inward, the whole forming a structure resembling a bird's nest. The involucral bracts are long, and cleft into a number of narrow lobes. The involucels, at the bases of the umbellets, are made up of entire or toothed lobes. The flowers are small and white, the central one of each umbel often purple, or all the flowers are pinkish. The calyx teeth are lacking. There are five petals, obovate, and with the tips turned in. Fig. 219. — Fruit of carrot (Daucus carota). A, cross-section; B, external view. (A, after Sargent). B X lo. UMBELLIFER^ 535 In the outer flowers, the petals are often two-lobed. The stylopodium is depressed or wanting, and has two curved stigmas. Fruit and Seed.^ — The fruit (Fig. 219) is oblong and dor- sally flattened. The five primary ridges of each carpel bear long hairs, and each of the four secondary ridges bears about ten long spines, at the ends of which are three or four hooked hairs. The oil tubes (vittas) are solitary in the in- tervals, that is, under the secondary ribs, and two are on the commissural side of each mericarp. The seed is flattened dorsally, and the face plane or slightly curved. Geographical. — The wild form of Daucus carola is a native of Europe and Asia. It has become common throughout North America, in many places proving a troublesome weed. Alb the cultivated forms of carrot are con- sidered to be derived from this one wild form. Fig. 220. — Types of carrots (Daucus carota). A, Garden Ball; B, Early Scarlet; C, Oxheart; D. Chantenay; E, True Danvers; F, Saint Vallery; G, Long Orange. Varieties. — There are numerous \arieties of carrots vary- ing as to size, shape, color, and quality. As to shape of 536 BOTANY OF CROP PLANTS the vegetable, varieties may be divided into two groups (Fig. 220). 1. Roots distinctly pointed, tapering (Long Orange, Saint Vallery). 2. Roots blunt at the tip, not pointed (Early Scarlet Horn, Ox-heart, Chantenay, Stump-rooted Half Long Red). The roots may be white (Large White, White Vosges, White Belgian), red (Carentan), orange or orange red (Early French Forcing Oxheart, Long Orange), or purple-violet (some Egyptian and Spanish varieties). Uses. — Medium-size carrots, particularly those with yellow or orange flesh, are used as a table vegetable and for the seasoning of soups and stews. The larger, coarser varieties, such as Large White, Large Yellow Belgian, Danvers and White Vosges, are grown for feeding stock during the winter season. The yellow coloring matter, carotin, is sometimes extracted from the roots and used for coloring butter. PASTINACA SATIVA (Parsnip) Habit, Roots, and Stems.^ — The parsnip is of either annual or biennial duration. When grown from seed, a fleshy hypocotyl and tap root are first formed; these consti- tute the "parsnip" vegetable. In the wild form, the root and hypocotyl are thin, tough, and woody. During the second season, a branching stem is sent up to a height of from 2 to 3 feet. The tall, erect stems are grooved, smooth or somewhat downy pubescent, and become hollow. . Leaves. — The lower and basal leaves are petioled, pinnately compound, the thin segments ovate or oval, lobed, incised or dentate. The upper leaves are sessile, much smaller than the lower, and not so deeply lobed. The terminal leaflet of each leaf is usually three-lobed. UMBELLIFER^ 537 Inflorescence and Flowers.— The flowers (Fig. 221) are in broad compound umbels usually with 7 to 15 main "rays/ ' each terminated by a small umbellet. There are no involu- cres and involuccls in the parsnip, thus differing markedly Fig. 221. — Leaf and inflorescence of parsnip (Pastinaca sativa). from the carrot. The flowers are yellow. The calyx teeth are very small or absent, the petals incurved and small, the stylopodium depressed, and the ovary inferior. Fruit and Seed. — The fruit (Fig. 218) is broadly o\al and much' flattened dorsally. The dorsal and two intermediate 538 BOTANY OF CROP PLANTS primary ribs are thread-like, while the lateral ribs are expanded into broad, flat wings, with those of the two mericarps con- tiguous. The oil tubes are solitary in the intervals; there are four on the dorsal side and two to four on the commissural side. The olive-green seeds are flattened dorsally. The seeds are very short-Hved. Geographical. — The wild parsnip, Paslinaca saliva, from which our culti- vated varieties are derived, is a native of Europe. This wild form has be- come naturalized in many sections of North America, occurring as a weed along roadsides and in waste places. Varieties.- — There are comparatively few parsnip varieties. Probably the most popular sorts are the Guernsey and Hollow Crown. In both of these, the crown is concave. Fig. 222. — Celery (Apium graveolens). A, schizocarp, external, X 15; B, diagrammatic cross-section of schizocarp, X 20. APIUM (Celery and Parsley) Generic Description.— Members of this genus are annual or perennial herbs with pinnately divided leaves. The white or grtemsh. flowers are in compound umbels. The involucre and involucels may be present or wanting. The calyx teeth UMBELLIFER^ 539 arc absent. As in many umbellifers, the petals are turned in at the tip. The fruil (Fig. 222) is flattened laterally, broader than long, smooth or covered with protuberances. The mericarps have pronounced corky ribs; the oil tubes are solitary in the intervals, with two on the commissural side. Geographical. — There are about 18 species in this group, distributed chiefly in the Eastern Hemisphere. There are two well-known cultivated species (parsley and celery) both of which are natives of Europe, and an indigenous species, A pi urn leplophyUum. These three species are distinguished in the following key. Key to Principal Species of Apium Flowers greenish-yellow, Apium pclrosclinum (common parsley). Flowers white. Leaf segments broad, Apium gravcolcns (celery and celeriac). Leaf segments narrow, Apium Icptopliyllum (fine-leaved marsh parsley). APIUM PETROSELINUM (Parsley) Description. — Common garden parsley is a biennial, the first season throwing out a dense whorl of radical leaves that are bipinnate, triangular in outline, and with the segments ovate, and dentate or incised. During the second season, there is sent up an erect, highly branched stem, i to 3 feet high. The upper leaves are also bipinnate, but the seg- ments are linear-oblong and entire. The inflorescence is a compound umbel with linear involu- cral bracts and awl-shaped involucellate bractlets. The flowers are greenish-yellow. The fruit is ovate, smooth, and with pronounced ribs. When large parsley seed is used the plants from them have larger and earlier foliage and are more capable of renewing the tops after being cut back than plants from small seed. Varieties. — As to leaf characters, there are two types of parsley: 540 BOTANY or CROP PLANTS 1. Plain Parsley. — ^Leaves plain, not curled. 2. Double Curled, Dark Moss-curled, Fern-leaved Parsley. — Leaves curled. The turnip-rooted or Hamburg parsley is a type bearing a small, fleshy root, which is the edible part of the plant. APIUM GRAVEOLENS (Celery and Celeriac) Description. — This species is either annual or biennial in habit, most commonly the latter. When grown from seed, there is formed, in the cultivated sorts, a clump of leaves with thick, fleshy leaf stalks. The leaf stalks are the edible por- tions of common celery. If the plants have been stunted or set back in their development, seed stalks may be sent up the first season. Of course, in celery growing, the ^^ seeder s^^ are undesirable and every effort is made to pre- vent their appearance. Normally, however, seed stalks are sent up from the short rootstock the second season. This stem is erect, glabrous, and i to 3 feet high. The leaves are pinnately compound with three to five oval, coarsely toothed or incised leaf segments. The small white flowers are in umbels. Involucre and involucels are small or wanting. The fruit is oval, flattened laterally, and has corky ribs. The oil tubes are solitary in the intervals and two in number on the commissural side. Geogr^hical. — Apium graveolcns, the wild form giving rise to our cultivated celery and celeriac, is a native of Europe. In eastern United States, it has escaped from cultivation, and it is said that in the salt marshes of California it has become naturalized. Types and Varieties.^ — There are two types into which the cultivated celery has been modified by breeding and selec- tion: (i) common celery, with enlarged, tender, edible leaf stalks, and (2) celeriac, ''German celery" or turnip-rooted celery {A, graveolens var. rapaceum), with a fleshy, turnip- UMBELLIFER^ 541 like rootstock, 2 to 4 inches long. 'J'hese rootstocks (oii- stitute the edible portion of the plant (Fig. 223). There are two general types of the common celery: (1) self-blanching varieties — quick-growing, very tender, easily- blanching sorts, especially adapted for fall and early winter use (White Plume, Golden Self-blanching). Blanching (see page 250) is secured by keeping the leaf stalks away from the Fig. 223. — Celeriac (Apium graveolens). {After Vilmorin.) light; the leaf blades, however, are permitted to grow in the light, so that the processes of food-making proceed in a normal manner, and the stalk is not stunted. Chlorophyll is formed only in those parts of the plant exposed to the light directly. Boards, paper or earth are placed about the stalks to exclude the Hght. (2) Green or unnter varieties — not as quick-growing or easily blanched as those of the preceding type and, further- 542 BOTANY OF CROP PLANTS more, with better keeping qualities when stored for the winter (Giant Pascal, Boston Market, Winter Queen, Giant White Solid). All cultivated varieties of celery require cool weather and plenty of moisture for their best development; they are intolerant of excessive heat. Celery culture is carried on with the greatest success on reclaimed muck soils in regions with a cool climate. Uses. — Celery is grown principally for the thick, fleshy leaf stalks. The leaves are also used for garnishing and seasoning, and the seeds are used for flavoring salads and soups. The fleshy root of celeriac is used as a flavoring or is stewed separately. References Coulter, J. M., and Rose, J. N.: Monograph of the North American Um- belliferae. Contr. U. S. Nat. Herb., 7, No. i: 1-256, 1900. CHAPTER XXXV VACCINIACE^ (Huckleberry Family) This is a widely distributed family occurring in tropical, temperate, and arctic regions. It is closely related to the heath family {EricacecE) which possesses such well-known plants as kinnikinic {Arctostaphylos uva-ursi), the creeping wintergreen (Gaultheria) , American Laurel {Kalmia), Labra- dor tea (Ledum), Azalea, Rhododendron, and trailing arbutus (EpigcBa repens). In the heath family, however, the ovary is superior instead of inferior as in the huckleberry family. There are two important genera from an agricultural stand- point, Vaccinium and Gaylussacia. The former genus includes a rather large number of species grown for their fruit; these take in the bilberry, blueberry, cranberry, huckleberry, and whortleberry. Gaylussacia spp. are known as tangleberry, blue huckleberry, and dangleberry. Gaylus- sacia may be distinguished from Vaccinium by its ten-celled ovary, with one ovule in each cell. In Vaccinium the ovary is four- to five-celled, or sometimes eight- to ten-celled by false partitions. Habit. — The plants belonging to this group are erect or prostrate shrubs or, in a few instances {e.g., Vaccinium arboreum, the farkleberry) a small tree. Some South American species are epiphytic. Leaves." — The leaves are simple, alternate, often thick and leathery and sometimes evergreen, and without stipules. Inflorescence and Flowers.^ — The flowers are solitary in the leaf axils (as in Chiogenes hispidula, the creeping snow- 543 544 BOTANY OF CROP PLANTS .^^ berry, or Vatcmium membranaceuni, the thin-leaved bil- berry), or in racemes (as in Vaccinium virgatum, southern black huckleberry, or Vaccinium oxy coccus, the European cranberry). The flower pedicels are usually bracted. The small flowers are perfect, sympetalous, and usu- ally actinomorphic (Fig. 224). The calyx (Fig. 225) forms a tube, grown fast to the ovary, the limb (free portion) four- to five-lobed or four- to five-cleft, and either persistent or deciduous. The sympetalous corolla is divided into four or five lobes or very rarely into nearly separate petals, as in the cran- berries. The corolla may be either globe-shaped, bell- shaped, urn-shaped, or tubular. There are twice as many Fig. 224. — Floral diagram of Vaccin- ium. j/y/. - jfiy/e terminal anther orolla jtlamen 'jnectar Inland ^ calyx tube-^ locuies with , ovules Fig. 225. — Flower of Vaccinium. A, median lengthwise section; 5, external view. stamens as corolla lobes, and they are usually inserted at the base of the corolla; the filaments are commonly flattened, short, and either free or united; the two-celled anthers are VACCINIACE^ 545 upwardly prolonged into tubes, and open by a terminal pore (f'ig. 225). The ovary is inferior, four- to five-celled or eight- to ten-celled by false partitions, and has a filiform style, a small stigma, unmodified at the tip, four- to five-lobed or four- to five-toothed, and one to several ovules in each locule. Fruit. — The fruil is globular and either a many-seeded berry (as in Vaccinium) or drupe-Hke (as in Gaylussacia) . The seeds are small, compressed, and have a bony seed coat, and a small embryo imbedded in a fleshy endosperm. VACCINIUM The representatives are shrubs or small trees. The leaves are leathery. The flowers are solitary or in short racemes. They have characters as described above under the family. PoUination.^ — Coville describes the method of pollination in a blueberry. It is quite probable that this will hold true for most Vaccinium species. The bell-shaped flower is in- verted, the 10 stamens hang downward and are shorter than the style. The flat filaments form a close circle about the style, being held together by the interlacing mar- ginal hairs. When an insect visits the flower, the only easy way it can get at the nectar, which is situated at the base of the stamens on their inner side, next to the style, is to push its proboscis between the anther tubes. In this process, the mature pollen grains are shaken loose, and some of them stick to the insect's body, to be carried by it to flowers visited sub- sequently. The anther pores open inward. The stigma is top-shaped and the very apex is the only receptive portion. Hence the rim of the stigma just below the receptive surface, prevents the falling pollen from reaching this surface. In this way self-polKnation is to a large extent prev^ented. If pollen from the same plant is used in pollination, the fruit that is formed remains small and green, and later drops ofl". 35 546 BOTANY OF CROP PLANTS This fact serves to emphasize the need, in the propagation of blueberries by cuttings, of making the plantation from cuttings of a number of different bushes. Fruit.^ — The fruit is a many-seeded berry. It matures about two months after flowering. The berries are most commonly blue-black in color, although albino forms are known to occur. The calyx is permanently attached to the fruit. Berries may remain on the bushes a month or more after they have reached maturity without losing their flavor or firmness. Geographical, — The genus is widely distributed in the northern hemisphere, mostly in North America and the Himalayas. It includes about 125 species, about 27 or more of which are native to North America. Key to Chief Fruit-bearing Species of Vaccinium Fruit red in color. Stamens included, V. vitis-idaa (cowberry, mountain cranberry, foxberry). Stamens exserted. Leaves ovate, acute at the apex; stems slender, creeping; berries globular, V. oxycoccus (small cranberry). Leaves oval or oblong, obtuse or retuse at the apex; stems stout, creeping, with ascending branches; berries egg-shaped or oblong, V macrocat pon (American cranberry). Fruit blue or black in color. Plants low, seldom over 2 feet tall. Leaf surfaces free of hairs. Berries blue. Leaves shining above, V. ccepitosum (dwarf bilberry). Leaves not shining above, V. vacUlans (low blueberry, blue huckle- berry). Berries black. Flowers solitary in leaf axils, V. myrtillus (whortleberry, bilberry). Flowers in groups in leaf axils. Fruit with bloom, V. anguslifolinm (low blueberry). Fruit without bloom, V. nigrum (low black blueberry). Leaf surfaces hairy, V. canadense (Canada blueberry). VACCINIACE^ 547 Plants tall, 3 to 12 feet, and spreading. Flowers solitary in leaf axils, V. ovaUJolium (tall or oval-leaved bilberrj')- Flowers in groups in leaf axils. Fruit blue, V . corymbositm (high-bush blueberry, swamp huckleberry). Fruit black, V. alrococciim (black blueberry). GAYLUSSACIA (Huckleberry, Tangleberry, Dangleberry) Description. — Members of this genus are shrubs with alter- nate and entire or finely toothed leaves. The inflorescence is a raceme. The small white or pink flowers are on two-brac- teolate pedicels. The calyx tube is short, five-lobed or five-toothed, and persistent. The stamens are 10 in number, and their anthers open by terminal pores. The fruit is described as a berry-like drupe, or lo-celled drupe with 10 seed-like nutlets. The ''seeds" are each covered with endocarp. Geographical. — The genus is distributed throughout North and South America. It possesses about 40 species. There are five species of Gaylussacia growing in North America. Key to North American Species of Gaylussacia Leaves evergreen, finely toothed, G. brachycera (box-huckleberry). Leaves deciduous, entire. Fruit with a bloom, G. frotidosa (blue huckleberry, tangleberry, dangle- berry) . Fruit without a bloom. Leaves 2 to 4 inches long, G. iirsina (Carolina huckleberry). Leaves i to 2 inches long. Bracts small, deciduous, G. resinosa (black or high-bush huckleberry). Bracts large, persistent, C. dumosa (dwarf or bush huckleberry). Of the above species, G. resinosa is, as a rule, the common black huckleberry on the market. This species is a shrub, i to 3 feet high, with stiff branches, oval or oblong leaves that are very resinous when young, a few pink or red flowers and sweet, seedy, black fruit. It grows in sandy soil from New- foundland to Georgia, westward to Kentucky and Manitoba. 548 BOTANY OF CROP PLANTS CRANBERRIES Some botanists place the cranberries in the genus Oxycoc- cus, separate from the blueberries, huckleberries and bil- berries, which are included in the genus Vaccinium. In Oxy coccus the corolla is deeply four-cleft or four-divided, while in Vaccinium it is bell-shaped or cylindric and divided only at the very apex. We have placed all the cranberries in the genus Vaccinium. There are two principal species of ' M 'S * m_rjlf^Sr\ l^ ^^^r /^ ^ s Fig. 226. — American cranberry (Vaccinium macrocarpon). cranberries grown in America: American cranberry {Vac- cinium macrocarpon) and the small cranberry {Vaccinium oxycoccus). These are distinguished in the key above. It seems that the appearance of the flower in the bud has prob- ably suggested the name cranberry or ''craneberry." Just before the flower opens, the pedicel, calyx and corolla resem- ble the neck, head, and bill of a crane. Vaccinium macrocarpon (Large or American Cranberry) . — This is a low, slender, creeping plant with oblong or oval VACCINIACE^ 549 leaves, whitened beneath, and with rolled margins. The flowers are on short upright one-year-old shoots; they occur in very short clusters; the corolla is hght pink. The berry is red, ovoid, oblong, or almost globular. At the summit of the fruit, are four persistent, short calyx lobes, bent inward. This species is found wild in boggy land in the northern part of the United States, adjacent Canada, south along the eastern coast to Virginia and North Carolina. It is also found in South America. It is the cranberry that is culti- vated to a large extent in the cranberry centers in this coun- try — Cape Cod, New Jersey, Wisconsin, Michigan and Min- nesota. The cultivation of cranberries in the United States is practically confined to cool, moist boggy regions. Cran- berries are grown in natural or artificial bogs, which are capa- ble of being drained or flooded at will. Types. — Corbett divides American cranberries into four groups, based upon fruit shape. 1. Bell. — These are the most popular and include such varieties as Early Black and Centennial. 2. Bugle. — Mathews, Howe, Centerville, Dennis. 3. Olive. — McFarlin's, Howes, Jumbo. 4. Cherry or Spherical Cranberries. — Early Red, Arpin, Makepeace. Vaccinium oxycoccus (Small Cranberry) .^ — This is the cranberry of the Old World. It is a slender, creeping plant with thin stems, 4 inches to i foot long, and with ovate, acute or acuminate leaves, dark green above, whitish beneath. The flowers are very similar to those in the preceding species. The berry is red, globular, four-celled, and often spotted when young; it is smaller than that of the American cranberry, although considered by some of superior quality. The small cranberry is a native of alpine and subarctic 550 BOTANY OF CROP PLANTS regions of Asia, Europe, and America. It is not cultivated in America to any great extent. Vaccinium vitis-idaea (Mountain Cranberry, Windberry, Wolberry, Cowberry, Foxberry).^ — This is a low evergreen shrub with creeping stems and thick, leathery leaves. The flowers are in short, terminal, one-sided clusters. The berries are dark red. This plant grows wild from Massachusetts to Labrador, west to British Columbia and Alaska. Although not cul- tivated, the natives, particularly of Nova Scotia, gather large quantities of this wild cranberry and ship them to eastern markets. HUCKLEBERRIES AND BLUEBERRIES Both of the above names are applied to the fruit of species of Vaccinium and Gaylussacia. However, it is uncommon to see the name blueberry given to the fruit of Gaylussacia spp. These bear lo seeds in each fruit, and although not as numerous as in the berry of Vaccinium, are more trouble- some. There are two general types of blueberries: high- bush blueberries {V. corymbosum, and 'V. atrococcum), and low-bush blueberries {V. canadense, V. angustifolium, V. nigrum, and V. vacillans). The common black huckleberry on the market is Gaylus- sacia resinosa. Vaccinium angustifolium is a rather common low-bush blueberry, while V. corymbosum' is the species most desirable for cultivation. References CoviLLE, Frederick V.: Experiments in Blueberry Culture. U. S. Dept. Agr. Bur. Plant Ind. Bull. 193: i-ioo, 1910. Davis, W. T. : High-bush Blueberries. Proc. Staten Island Assn. Arts and Sci., 2: 63-64, 1909. CHAPTER XXXVI OLEACE^ (Olive Family) Family Description. — This is a family of trees or shrubs. The leaves are opposite, exstipulate, and simple or pinnately compound. The inflorescence is a panicle, raceme, cyme or fascicle. The flowers are regular, and polygamous or dioecious; the small calyx h four-lobed, sometimes entirely absent; the regular corolla is four-parted, or of four distinct petals, or absent. There are two stamens, attached to the corolla or to the receptacle. The single pistil is compound, with a two-celled ovary, in each of which there are a few seeds, a short style, and capitate stigma; sometimes the style is absent. The frutt is either a capsule, samara, berry, or drupe. Geographical, and Economic Importance. — There are about 21 genera and 500 species distributed widely in tem- perate and tropical regions. The most important repre- sentative is the olive {Olea europoea). Other well-known members of the family are the lilacs (Syringa), privet {Ligus- trum). Jessamine {Jasminum) and ash (Fraxinus). OLEA EUROPCEA (OUve) Description. — The common olive is a small tree 20 to 25 feet high. All fruit is borne on two-year-old wood, and the same wood never bears twice. The lanceolate leaves are leathery, evergreen, entire, smooth, scaly, and arranged op- positely on the stem. Thefloivers occur in axillary racemes as a rule, although terminal inflorescences are more or less fre- quent. The flowers are usually imperfect. The small calyx is four-toothed, the corolla four-cleft, white or whitish, the stamens two, and the pistil one. The fruit is a purplish drupe. 551 552 BOTANY OF CROP PLANTS The olive is probably a native of the Mediterranean region. Its cultivation in this country is confined almost entirely to Fig. 227. — Olive (Olea europcea). Branch and fruit. {From Calif. Agr. Exp. Sla.) the warm, dry portions of California. The olive requires a mean annual temperature of 57°F., and it is claimed that at no time should the temperature go below i4°F. OLEACE^ 553 Seed Germination. — If olive seeds do not receive some treatment before planting, they will not germinate for a year or more. This delay in germination is due to the thick, stony covering, and to the oil present which inhibits water penetration. The delay in germination has been overcome, in part, by various means, such as soaking in warm water, soaking in alkaline or acid solutions, cracking the stones, and clipping the apex of the seed. The last method appears to be the best. Propagation. — The olive is very easily reproduced vege- tatively; in fact, cuttings of any kind will grow. For propa- gative purposes use may be made of green cuttings with the leaves on, of chips from old trunks, of young or old limbs, and even of knaurs. Knaurs are knots or excrescences formed upon the trunks of old trees. When limbs 2 or 3 inches in diameter are used, they are cut into lengths of i or 2 feet, each split lengthwise, and planted horizontally with the bark up. Sprouts readily arise from the section of trunk, and such sprouts may be allowed to continue their growth where they are, or be made into green cuttings. Uses. — Olives are eaten either in the green or ripe state. They are usually "pickled," and left whole, or "stuffed." Olive oil is an important commercial product. The best equality of oHve oil, known as "Virgin oil," is made from hand-picked fruit. The fruit is crushed so as not to break the seed. The pulp is treated with water and again pressed, yielding a product which is employed as salad oil. The pressed pulp is again treated with hot water, and subjected to high hydraulic pressure; this process gives an oil known as "ohve oil foots." It is employed in the manufacture of soaps, particularly castile soap, and as a lubricant. An oil is also extracted from the seeds. It is much like that from the pulp. CHAPTER XXXVII CONVOLVULACEJE (Morning Glory Family) corolla iube - -stigma The representatives of this family are found chiefly in warm climates. There are close to 900 species in 400 genera. A number are of economic importance, among which may be mentioned the sweet potato, man-of-the-earth {I pomoea pan- durata), used as food by the Indians, moon-flower {Ipomoea bona-nox), morning glory (Ipomoea purpurea) , cypress vine {Quamoclit quamoclii) and the bindweeds {Convolvulus spp.). Habit. — Most of the repre- sentatives of this family are twining or trailing herbs; some tropical species are shrubs or trees, often with a milky juice. Leaves. — The leaves are alter- nate, exstipulate, entire, den- tate, lobed, or dissected. Inflorescence and Flowers. — The flowers are in an axil- lary cyme, or sometimes soKtary. They are regular, perfect and sympetalous (Fig. 228). The calyx is attached below the ovary, five-parted or five-divided, usually persistent, and imbricated in the bud. The corolla is plaited, convolute, or twisted in the bud, and becomes funnel-form, salver-form, campanulate, or tubular, with a five-angled, or five-lobed, or entire hmb (Fig. 228). The five stamens are inserted on the 554 cahx Fig. 228. — Flower of sweet potato (Ipomcea batatas), length- wise section. (After Sargent.) CONVOLVULACE^ c- r - tube of the corolla and alternate with its lobes; all are anther-bearing. The filaments are filiform, or dilated at the base, and equal or unequal. The anthers are two-celled and longitudinally dehiscent. The ovary is superior and usually has two cells (rarely three cells), each of which bears two ovules. In some instances, the ovary is falsely divided into four to SIX cells, each with a single ovule. Fniit.-The/m// is a capsule; its seeds are endospermous. Key to Important Genera Stigmas capitate (knob-like). Stamens and style exserted, Quamoclit. Stamens and style included, Ipotncea. Stigmas two, filiform or oblong, Convolvulus. IPOMGEA BATATAS (Sweet Potato) ^ Roots and Stems.-The sweet potato is a sinistrorse-twin- ing, trailmg, perennial herb with very much thickened roots The "sweet potato" itself is often designated as a ''root tuber." The fleshy roots have stored within them large quantities of starch. They should not be confused with the tubers of the Irish potato. Sweet potato " tubers " are roots while Irish potato ''tubers" are stems. Propagation. ~ln the propagation of sweet potatoes, these fleshy roots are cut lengthwise, and the cut surface of each piece IS laid against moist earth until it produces sprouts Then the piece is further cut up and each portion replanted It IS necessary to leave a part of the epidermis in order that adventitious buds will develop. Sweet potatoes are fre- quently propagated by vine cuttings. Leaves.— These are alternate, heart-shaped, pctiolate dark green, and glossy. Inflorescence and Flowers.-The large, purple, con- spicuous flowers are axillary, solitary or cymose. The 556 BOTANY OF CROP PLANTS sympetalous corolla is i to 2 inches wide', funnel-form, and has a five-lobed limb, and plaited tube. The corolla is folded longitudinally and twisted usually to the right in the bud. The stamens are as given under the family description. The two- to four-celled ovary has a thread-like style which bears one or two stigmas. The fruit is a capsule. In northern latitudes, the sweet potato rarely blossoms, and never matures seeds. Geographical, and Environmental Relations. — The original home of the sweet potato is the West Indies and Central America. Since the sweet potato is of tropical origin it is largely grown in the Southern States, the five leading ones being North Carolina, Georgia, Alabama, Louisiana and Mississippi. Ample sunshine and high temperatures favor its growth. Although a heavy rainfall is desirable during the first part of the growing season, the maturing of the roots proceeds best with rather dry weather. They do best in well-drained, light soils. Closely Related Species. — The southern, juicy varieties of sweet potatoes are called "yams." They should not be confused, however, with the true yams, or Chinese potatoes of commerce, which belong to the species Dioscorea batatas, in a famil}' (Dioscoreaceae), closely related to lilies. This is a tall climbing plant with simple cordate, shining leaves, small, white flowers, and large tubers. T)rpes and Varieties.^Sweet potatoes may be divided into two groups upon the basis of the amount of water and sugar present: (i) Dry sweet potatoes are ones in which the flesh is dry, mealy, and yellow; they are the sorts most de- sired in the Northern States. The Jersey type, which includes spindle-shaped varieties, is probably the best known. (2) " Yams'' are sweet potatoes in which the flesh is watery, rich in sugar, soft and gelatinous when cooked. They are the sorts most in demand in the South. Common southern CONVOLVULACE^ 557 sorts ("yams") are Triumph, Nancy Hall, Dooley Yam, Vineless Yam, Sugar, Southern Queen, Florida. Fig. 229.— Types of sweet potatoes (Ipomoea batatas). .4, Black Spanish- B. Shanghai; C. Big Stem Jersey; 73, Red Bermuda; R, Southern Oueen' {Modified after Corbett.) Fig. 230.— Types of sweet potatoes based upon the character of the foliage A , entire or round; B, shouldered; C, deeply cut or lobed. (After Price Texas Agr. Exp. Sta.) Leaf Shape as Basis of Classification.— Price has classified the varieties of sweet potatoes according to leaf shape. These groups are as follows: 1. Leaves round or entire (Fig 230, A) (Pumpkin, Shanghai, Southern Queen, Big Stem Jersey). 2. Leaves "shouldered," that is shallowly and broadly notched on cither 558 BOTANY OF CROP PLANTS side near the apex (Fig. 230, B) (Delaware, Early Golden, Yellow Jersey, Red Bermuda). 3. Leaves lobed (Fig. 230, C) (Barbadoes, Sugar, Yellow Yam, Vineless Yam). Sweet potato varieties may have skin color that is white, straw, red, or purple. 1. Skin white (Vineless Yam, Early Golden, General Grant). 2. Skin straw (Orange, Delaware, New Jersey). 3. Skin red (Pumpkin, Red Bermuda). 4. Skin purple (Black Spanish, Brazilian). Uses.^ — Sweet potatoes are used chiefly as a human food. Some of the coarser varieties are grown for hog pasture. The vines have some value as a stock food. Flour, starch, glu- cose, and alcohol are minor products of the root. Small- sized sweet potatoes, known as "seconds," are canned. Kiln-dried sweet potatoes produce a product very similar to corn meal in its chemical composition. References Groth, B. H. a.: The sweet potato. Contrib. Bot. Lab. Univ. of Pa., 4: 1-104, 1911. CHAPTER XXXVIII SOLANACE^ (Potato Family) / The potato family is a large one, chiefly tropical; it has about 1, 600 species in 70 genera. A number of these are important medicinal and food plants. Here are included such economic forms as Red or Cayenne pepper, tobacco, common Irish potato, eggplant, tomatoes, belladonna (Atropa belladonna) which furnishes the atropin of commerce, thorn apple (Datura), petunia, etc. Habit of Plants. — Representatives of the family are either herbs (potato, tobacco, tomato), shrubs {Lycium spp.), vines (Solanum dulcamara, bittersweet), or trees in some tropical species of Datura. Leaves — These are alternate, rarely opposite, without stipules, and entire, toothed, lobed or dissected. Inflorescence and Flowers.— The inflorescence is mostly cymose, sometimes imperfectly racemose, umbellate, or paniculate. The flowers (Fig. 232) are regular, or nearly so, perfect, and vary in color. The calyx is inferior, and usually with five united lobes. The corolla is sympetalous, mostly five-lobed. The corolla varies considerably in shape: rotate (tomato), bell-shaped (Physalis), funnel-form (Lycium vul- gare), salver-form or tubular (Petunia spp.) There are as many stamens as corolla lobes, alternate with them, and inserted on the tube; in most genera, the stamens are all equal and bear perfect anthers, but in Petunia, for example, there are four perfect stamens, the fifth being very much reduced or entirely absent; the anthers are two-celled, dehis- 559 560 BOTANY OF CROP PLANTS cent at the apex or along the sides. The single ovary is usually two-celled (rarely three- to five-celled, as in Ly- copersicon spp.), the numerous ovules being on axile pla- centas; the style is slender, simple, and the stigma terminal. Fruit. — The fruit is either a berry (potato, tomato), or a capsule (tobacco, petunia). In both cases, it bears numer- ous seeds, which have a fleshy endosperm. Key to Important Genera Fruit a berry (Fig. 233). Anthers opening by a terminal pore or slit (Fig. 232J, Solatium (potato and eggplant). Anthers opening longitudinally Flowers white, Capsicum (pepper). Flowers yellow, Lycoperskon (tomato). Fruit a capsule (Fig. 244). Capsule generally prickly, Datura (thorn apple, Jimson-weed). Capsule not prickly. Flowers paniculate or racemose; stamens nearly uniform in length, Nicotiana (tobacco"). Flowers solitary; stamens very unequal, Petunia (petunia). SOLANUM Habit.^ — The Solanums are either erect herbs (as S. nigrum, the black nightshade, and the common potato, etc.), or climbing herbs {S. dulcamara , bittersweet). In most species, the stems and leaves bear a stellate (star-shaped) pubescence. Leaves. — The leaves are alternate, exstipulate, and lobed or pinnately dissected. Inflorescence, and Flowers.^ — The inflorescence is cymose (bittersweet), umbellate (black nightshade), racemose {S. carolinense, horse nettle), or rarely paniculate. The flowers (Fig. 232) are perfect and regular; in color, they are white {S. tuberosum varieties and 6*. nigrum), blue {S. elceagni- folium, silver-leaved nightshade, and S. tuberosum varieties), SOLANACE^. 561 yellow (S. rostratum, sand l)ur), or purple (5. dulcamara). The calyx is bell-shaped or rotate, generally live-parted or five-cleft. The corolla is rotate or rarely broadly bell- shaped, the tube very short, the limb plaited, five-angled or five-lobed. There are five stamens inserted on the throat of the corolla (Fig. 232); the filaments are short, the anthers converge around the style, and are usually dehiscent by a terminal pore, sometimes by a short introrse terminal slit, and sometimes longitudinally. The ovary is superior, usu- ally two-celled; its style is slender and simple, and the stigma terminal. Fruit.^ — The fruit is a many-seeded berry; the calyx is persistent at the base, and in some species {S. rostratum) encloses the berry. Geographical. — There are about 900 species of Solanum, widely distributed, but most abundant in tropical America. Key to Important Species of Solanum Not tuber-bearing. Plant not prickly or spiny. Erect herbs or shrubs. Fruit ovoid or egg-shaped, yellow with purple or violet streaks or splashes, often 4 to 6 inches long, S. muricaliim (pepino^ melon pear) . Fruit a small, spherical berry, not over i inch in diameter. Peduncles one- to three-flowered; ripe berries green, .S'. trijloriim (wild tomato, cut-leaved nightshade). Peduncles bearing small cymes, three- to ten-flowered; ripe berries black, S. nigrum (black or common nightshade). Climbing vines, S. dulcamara (blue bindweed, bittersweet). Plant prickly or spiny. Berry not enclosed by the calyx. Flowers light blue or white; fruit a small spherical berry, 5. carolincnse (horse-nettle). Flowers purplish; fruit large, S. melongena (egg plant). 36 562 BOTANY OF CROP PLANTS Berry enclosed by calyx, S. roslraMim (sand bur, buffalo bur). Tuber-bearing.* *NoTE. — Berthault in his monograph on the tuber-bearing Solanums, has a key to 37 species. A portion of this key is here included (modified) to show the relation of common potato to some \vild tuber-bearing species. Corolla rotate. Points of sepals long and tapering. Leaves oval, 5. tuberosum (common potato). Leaves elongated, S. immite. Points of sepals long, not tapering much; leaves oval, S. chiloense. Points of sepals short. Anthers straight, smooth, somewhat elongated, S. utile. Anthers swollen, roughened, S. maglia. Corolla star-shaped, S. jamesii, S. commersonii, etc. SOLANUM TUBEROSUM (Potato) This species includes all the varieties that are of value for food. They are usually called Irish or common potato, but also white, English, and round potato. Habit.- — The potato is a branched, more or less spreading herb, growing to a height of 2 to 5 feet or more. It has annual aerial stems, but is practically perennial by means of its tubers or underground stems. Roots. ^^Upon the whole, the development of the root system is less pronounced than in most other crops. The roots are fibrous and fine. They penetrate the soil to a depth of 2 to 4 feet and frequently extend horizontally 2 feet or more from the plant. Stems.^ — Potato stems are of two general kinds as to medium in which they grow: Underground and aerial. The underground stems (Fig. 12) are slender rhizomes, or are swollen to form tubers ("potatoes")- The aerial stems are the ordinary foliage-bearing stems. The discussion of rhizomes and tubers is given on pages 29 and 31. Stem (aerial).- — The aerial or foliage stem of the potato is herbaceous and generally erect when young, but usually SOLANACE^ 5^\3 becomes spreading later. It is smooth and generally solid. It has no ribs at first, but as it develops, it becomes more or less quadrangular. Leaves. — Potato leaves are compound pinnate, with more Fig. 231. — Flowering branch of potato (Solanuni tuberosum). or less petroled leaflets. The petiole bears a number of supplementary leaflets which vary in number and importance with the age of the plant. The rachis is decurrent (Fig. 12) on the stem. The leaflets are oval, acuminate, and the base heart-shape or oblique in shape. The leaves as well as the stems are characterized by a narcotic smell. At the begin- 564 BOTANY OF CROP PLANTS ning of their development, the leaves are often simple, but they increase in complexity with age. The single terminal leaflet, which frequently appears alone, is soon followed by two lateral leaflets, and these by others, so that the leaf soon becomes distinctly pinnatifid. Considerable differences have been found to exist in the appearance of the leaves of the different agricultural varieties. Flower (Fig. 232). — The corolla is tubular, with five lobes. -terminal pore anther ' Fig. 232. — Potato (Solanum tuberosum). A, berry; B, flower in median lengthwise section; C, floral diagram. It is white, yellow, purple, or blue in color and i to i)-^ inches in diameter. There is a single whorl of five stamens which al- ternate with the corolla lobes, and are attached to the tube. The stamens are straight, and bear erect, yellow anthers which are longer than the filaments and open only at the top. Two kinds of pollen grains have been observed. Those of most varieties are variable in size, irregular in shape, rough- ened, and largely impotent. Those of the other type are smooth, spherical, and potent. The latter kind are found only on varieties which bear fruit. Some varieties produce both kinds of pollen grains, but such plants do not always SOLANACE^ 565 produce fertile flowers. Hence while the presence of round pollen grains seems to be necessary to the production of fruit, their presence by no means assures that the ovary will be formed or fruit produced. The ovary consists of two carpels with numerous ovules in each locule. Opening of Flower and Pollination. — The anthers are mature at the same time that the stigmas are receptive. The flowers have been found to open between 5 and 6 o'clock a.m. The pollen is usually shed on the second day of bloom- ing, and at this time, the pistil is most receptive. The an- thers open at the top by a pore and, in some cases, spht for a short distance. The pollen is carried by the wind. The flowers produce no nectar and are not visited by insects to any extent, although several species of insects have been re- ported as visiting the flowers. East concludes from obser- vations of his own (and of others) that self-fertiUzation is natural to the species. The flowers wither about the fourth day, in the profuse-seeding varieties. Some writers report that fragrance is correlated with pollen yield, but East says he found no noticeable fragrance in American varieties. It is commonly thought that potatoes do not fruit as freely now as formerly, due to the fact that large production of tubers has caused a degeneracy in seeding power. While many of the varieties seldom bloom, and more rarely set seed, some of the best varieties bloom freely and under proper conditions set seed. Eraser says, as a result of working with 300 varieties, many of which were grown for several years, that it is seldom that a variety will not bloom at some time in its life and, furthermore, he found that many of the heaviest yielding varieties bloomed as freely as those of less value. In many varieties, the flowers do not open. In the Pearl variety. Fitch finds that tuber productiveness "is universally 566 BOTANY OF CROP PLANTS proportionate to the sexual development of the plant; that the most degenerate tuber is produced on the plant which carries fully developed flowers and virile pollen; while those plants on which only female portions of the flowers appear to be fully developed, produce tubers intermediate in form and yield, and that the best tubers and the largest yield are pro- duced by the type of plant whose flower buds do not even swell." Furthermore, these buds do not show any other color than green and they soon wither and break off. Fruit. — The fruit (Fig. 233) is a globular or short oval berry with two locules containing numerous seeds attached to the thick axil placenta and embedded in a green acrid pulp. The fruit is called by various names, such as "potato ball," "potato apple," or "apple," but is commonly referred to as the "seed ball." In color the seed balls are brown, purplish green, or green tinged with violet. Single fruits may contain from a few to as high as 200 or 300 seeds, but some- times no seed^ are produced. Fitch found no seeds in 650 seed balls of Early Rose. One seed ball from a Pearl crossed with a Rural contained no seed, while six seed balls of the reciprocal cross all bore abundant seeds. Removal of the early tubers induces fruit-bearing, while removal of the flowers is said to encourage tuber development. Seed. — The seeds are small, kidney-shaped, and embedded in the green, very acrid pulp of the fruit. Germination of Seed.^ — Potatoes are seldom propagated by seed except for the production of new varieties. As a result, many who are famiHar with tuber propagation know little or nothing about seed germination. Germination of seed begins in about five to seven days after planting, being complete in about eleven to sixteen days. Fig. 233. — Potato seed balls, showing a cluster, and lateral, sectional and basal views. {After Stuart, U. S. Dept. of Agri.) 568 BOTANY OF CROP PLANTS _^round hne The primary root appears first, soon becomes curved, and is followed by the axis of the hypocotyl. The cotyledon leaves are smooth, oval, and more or less elongated, while the first foliage leaves are provided with unbranched hairs. Development of the Seed- ling. — From the thirty-sev- enth to the fifty-sixth day after seeding, the stolons arise (Fig. 234); the first pair comes from the axils of the cotyledon leaves. These slender cylindrical stems possess small rudi- mentary leaves. They trail along on the ground and finally penetrate the soil. When their tips strike the ground, they begin to swell and form tubers. Hence the first tubers of the plant, grown from seed, are de- veloped at the tips of slender stolons coming from the axils of the cotyledon leaves. Roots soon arise from the stolons. Secondary stolons appear in the axils of the first fohage leaves. Tubers from Seedlings. — Tubers produced on seedlings are usually small the first year. However, Frazier reports a tuber weighing over 7 ounces that was formed the first year, and says that the Burbank potato was full-sized the first year from seed. It is reported from Svalof (Sweden) that tubers usually attain normal size and type after about the third year from seed. Tuberization.^ — It has been noted previously that tubers, foung tuber Fig. 234. — Young potato plant grown from seed. {After Percival.) SOLANACE^ 569 developed on a plant grown from seed, come at the tips of stolons arising on the stem above ground. However, when the tuber as a cutting is used in propagation, the young tubers form at the ends of long, thin rhizomes (underground stems) which arise underneath the ground from the main axis or stem (Fig. 12). The length of the stolon seems to be constant and a strong variety characteristic. In culti- vated varieties, it should not exceed 3 or 4 inches. In S. commersonii, it is reported as sometimes reaching a length of 10 feet. The tubers or swollen stems bear a number of buds, and these buds send out sprouts when the tuber is planted. As a rule, the tubers are formed beneath the ground as noted above; but in abnormal cases, or when disturbed by diseases, the above-ground stems may produce tubers. For example, when the fungus, Rhizoctonia, which shuts off the downward movement of elaborated foods from the leaves to the underground tuber-forming stems, is active, normal tuberization under ground is interfered with and the stems above ground will have a tendency to swell and produce small tubers. This phenomenon is often indicative of Rhizoctonia. Fungus Theory of Tuberization. — In general, it is found that darkness and low temperature favor the development of potato tubers. Tuberization is also facihtated somewhat by checking the growth of shoots or fruit. There is some basis for the theory that the formation of the tubers is associated with the presence of certain fungi. It is certain that tuber production is encouraged in certain orchids when the stem or root is infected with the proper fungus. The fungus appears to check the growth of the terminal bud and cause the development of hypertrophied cells. 570 BOTANY or CROP PLANTS When the potato was lirst introduced in France, it was found that when tubers were planted a crop was produced, but when seed was sown no tubers were obtained. From this it was inferred that when tubers were planted they in- fected the new ones, while the seed, free of fungi, did not furnish a supply to infect the stolons, and hence tubers could not form. However, no difficulty is now experienced in se- curing tubers from seed because the soil has become inocu- lated with the proper fungi. If this theory is correct, and there seems to be some evidence that it is, the potato tuber is in reality a gall, produced by a foreign organism. In the potato, tuberization has been induced in concen- trated solutions of sucrose or glycerin, etc., independent of fungi. Similar results have occurred in the case of orchids, onions, and radishes. From this it seems that the formation of tubers may result when the osmotic pressure in the cul- tural medium is high. However, this alone does not appear to be the only determiner, since different results follow the use of glucose and glycerine solutions of equal pressure. It certainly seems that plenty of sugar must be present for starch formation, and perhaps also for tubers to form. From this fact, that a more concentrated cell sap is usually present in fungi than in other plants, it does not seem unreasonable to suppose that the role of fungi in tuberization consists in raising the concentration of the media which they enter. It has actually been found that cultures of Fusarium in macer- ated potato tuber preparations increase the concentration. In this connection, it is suggested that low temperatures and dryness of soil may induce tuberization through increasing the concentration of cell sap. History.- — It seems "that the potato was cultivated and utilized by the Chilean and Peruvian people before the arrival of the Spaniards. In 1533, Pizarro found the Chileans SOLANACE^ 571 using the tubers of a plant as their principal food. There is no evidence that he or his party introduced them into Europe." Wild plants have been found on the Peruvian coast, on the mountains of Chile, Central America, Mexico, and southwestern United States. However, without a doubt Fig. 235.- -The wild potato of southwest United States (Solanum jamesii). (After Fitch, Colo Agr. Exp. Sta.) those which. were introduced into Europe were from culti- vated plants and not from wild tuberous American species. There" is little doubt that South America, in the neighborhood of Quito, is the place from which the potato was first intro- duced into Spain early in the Sixteenth century. After a careful study of all possible available types and species of Solanum, and a perusal of the available literature and records, F. Berthault has come to the conclusion that S. tuberosum is characterized and differentiated from all other wild tuberous Solanums by its floral characters, notably its rotate corolla, and its calyx which is always mucronate (sharp-pointed). All agricultural varieties of the cultivated 572 ' BOTANY OF CROP PLANTS plant (potato) have been found to correspond to these characters. Varieties. — There are at the present time over 500 named varieties of potatoes in the United States. Many of these variety names are found to belong to potatoes which are identical in all respects. Usually, new varieties are the seedlings of established varieties. The latest attempt at a classification of American potatoes is that of Stuart. In his "proposed system of classification" -^pendertn c- cortex vascular external medulla miernal medulla Fic. 236. — Diagrammatic section of potato tuber. he gives the following "groups": Cobbler, Triumph, Early Michigan, Rose, Early Ohio, Hebron, Burbank, Green Mountain, Rural, Pearl, and Peachblow. Tuber, sprout and flower characters are made the bases of distinction of the groups. The student is referred to Bull. 176, "U. S. Dept. Agr. (Professional Paper) for the descriptions of these groups. Fitch has also proposed a classification using about the same characters. Tuber Morphology. — The potato tuber is made up of a number of zones or layers which are commonly grouped as follows (Figs. 236 and 237): 1. Periderm or skin. 2. Cortex. 3. Vascular ring. SOLANACE^ 573 4. External medulla. 5. Internal medulla. According to Coudon and Boussard, these zones (except- ing vascular ring) are proportioned (by volume) as follows: Skin (average of two varieties) Cortex (average of two varieties) External medulla (average of five varieties) . Internal medulla (average of five varieties) . . Per cunt. 8.79 36 . I Q 34-17 U 95 -periderm outer cortex ^^A^ i-iSS Fig. 237. — Microscopic section through the "skin" and portion of cortex of potato (Solanum tuberosum). For consideration here, these zones are classified as fol- lows : 1. Periderm or skin. 2. Vascular ring. 3. Parenchyma. ia) Cortex. 1. External. 2. Internal. (6) Medulla. 1. External. 2. Internal. 574 BOTANY OF CROP PLANTS Periderm or Skin.- — The stolon, which develops into the tuber, possesses the true stem structure. It has a thin epidermis, an outer parenchyma tissue or cortex, fibro- vascular bundles, and an internal parenchyma or medulla. As the tuber develops, the cortex becomes relatively reduced, the vascular bundles separate and the. medulla becomes larger. The outer layers of cells of the cortex also undergo changes. The cells of these layers become corky and flattened, and so arranged that the vertical walls form straight lines and do not overlap. Their walls become suberized. The original true epidermis gradually dies and disappears entirely. These outer corky layers of cells constitute the periderm or skin of the potato. The outer- most layers of periderm split off, giving some varieties a characteristic rough appearance. The cells of the different layers of periderm vary in size and shape in different varieties. The number of layers is usually 7 or 8, but it varies from 5 to as many as 13 and even 17. At the eyes, the periderm (skin) becomes thicker. Lenticels are scattered over the tuber. Some claim is made that thick-skinned varieties are of better quahty than thin-skinned ones, but such is not always the case. A netted or rough skin develops on tubers of some varieties as they mature in storage, which suggests, that a rough or netted skin in these cases denotes maturity. Pos- sibly this is sometimes the source of the common idea that a rough-skinned potato is of superior quality. The size and type of netting is found to vary with the variety and the con- ditions under which grown. Smoother skins are usually found on potatoes grown on sandy soils than on those grown on heavy soils. It has been found that the thicker and rougher-skinned varieties stand up better in shipping, and are preferable for this purpose even though they may have no greater merit in other ways. SOLANACE.^i; 575 I Vascular Ring.- The vascuhir ring consists of n discon- tinuous circle of vascular bundles. It is located between the cortex and the medulla. At the eyes, the vascular tissue ap- proaches the surface of the tuber. It maintains, however, its proper relationship with the other tissue, i.e., between cortex and medulla. The cortical layer gradually becomes thinner as the vascular bundles approach the eyes. The vascular tissue is poor in starch. The vascular ring is easily recog- nized as a very narrow darkened ring near the edge of the exposed surface of a cut. Parenchyma. — Almost the entire mass of tuber tissue in- side of the periderm (skin), except the vascular tissue, is parenchyma, and will be referred to as such in this discussion. The parenchyma is divided into two principal parts: the cortex, and the medulla. Cortex.- — The cortical layer of the parenchyma is just within the periderm. It is separated from the medulla by the vascular ring. The outer cortex is made up of smaller cells than the inner cortex. The cells of the cortex are consider- ably smaller than those of the medulla, and hence the density of the cortex is greater. The cortex is darker in color than the medulla, which is probably due to its greater density. A thick and dense cortex indicates a potato of good quaUty. A thinner, more translucent cortex is said to indicate lower quaUty. The periderm, or skin, and the outer layers of cor- tex are removed when potatoes are peeled. MeduUa. — The medulla consists of all of the tuber inside of the vascular ring. It is divided into two parts, the exter- nal and the internal medulla. When a thin slice of potato is held up to the Hght, these two areas are easily distinguished ; the external medulla appears darker and denser; the lighter color of the internal medulla is due to its greater percentage of water, and considerably less starch and other solid matter. 576 BOTANY OF CROP PLANTS The internal medulla is usually more or less star-shaped. Many of the radiating areas of internal medulla penetrate deeply the outer medulla, some of them extending to the eyes. In some tubers, these two zones are more or less intermixed, with no definite zone boundaries. As a rule, in long potatoes, the central area is very much elongated and with lateral radiations, while in many round potatoes it is typically star- shaped. The greater the size of the internal medulla and the more its ramifications into the outer area, the poorer the quality of the tuber, since it means a larger area poor in starch and hence less mealy on cooking. Shape. — The common tuber shapes are round, oblong, and elongated, in outline. One dominant form is found in each variety but never one exclusive form. New varieties based on tuber form are produced by a selection of tubers and are maintained only by continued selection. • In tuber propagation, there appear among the normal- shaped tubers a number of aberrant (diverging) forms which are usually in the minority. Color.- — The common tuber colors are yellow, red, violet of different shades, and variegated. Bluish forms are also known. Color variation has been found in a number of cases. In propagation by cuttings, yellow and streaked tubers have appeared from colored ones (red and violet). Yellow tubers have given red and violet ones, a white tuber has given two red and two white tubers, and one with a bluish color has given a series white in color. The Pearl with a brownish-white or a well-russeted skin is from the Blue Victor which has a purple color often streaked with white. When the white streaks cover an eye, the tubers from the eye usually come true (white) in following genera- tions. The People's variety, also from the Blue Victor, is a deeper brown color than the Pearl. At the present time. SOLANACE^ 577 white-fleshed tubers are the only ones accepted in American markets. Yellow fliesh is correlated with a strong flavor and a poor quality, at least according to American standards. A number of yellow-fleshed varieties from France are found to be gummy and hard after boiling. They are considered by the French to be of prime quahty, however. In this coun- try, these varieties are considered of good quality for the making of salads and for frying. Eyes (Fig. 236).^ — The buds of the potato tuber usuall}- occur in groups, each group lying in a more or less depressed area. Such a group of buds is called the ''eye." The depression is the axil of a scaly leaf which was in evidence when the tuber was young, but later disappears. The ''eye brow" ("eye yoke") is the line above the depression — the line which separates the leaf from the stem. In reahty, the eye is a lateral branch with undeveloped internodes, the whole tuber being generally a much-branched stem and not a simple shoot. The central bud in the "eye" is commonly the largest and strongest. Fitch has noted that the "eye-brow" differs noticeably in vigorous and in degenerate tubers. In the latter, it is stronger and has a tendency to be longer. .Careful study shows that the buds or "eyes" are arranged alternately and at the same time spirally on the tuber. Be- ginning at one end of a tuber and proceeding toward the other end, at the same time turning the tuber, usually enables one to follow clearly the spiral arrangement. The so-called "seed end," "rose" end, or "crown" of the tuber is opposite the point of attachment to the stem. The "stem" end is at the "base" or heel of the tuber. The eyes are more numerous and more vigorous at the seed end. Ordinarily, the terminal bud (at the "seed end") is the strongest and under proper conditions will be 37 578 BOTANY OF CROP PLANTS the only one to develop. The sprout produced ])y the ter- minal eye is spoken of as the "master sprout." The eyes vary in different varieties from very deep to level with the surface; the latter condition results in smooth potatoes. Deep eyes tend to hold moisture; as a result, decay is invited and hastened when the potatoes are stored. Smooth varie- ties occasionally give rise to deep-eyed tubers, although, as a rule, eye depth is maintained by tuber propagation. It is likely that the deeper-eyed plants give rise also to smooth tubers and that in seed propagation the same results follow as in the case of form and color. The number of eyes varies considerably within the same variety; in one case, Rural New Yorker, it ranges from 7 to 28; and in Early Ohio, from 7 to 22. The number of eyes affects the quahty, since the poorer zone of the potato (in- ternal medulla) extends a branch to each eye, thereby in- creasing the percentage of internal medulla at the expense of the two outermost valuable layers. Germination or Sprouting of Tuber.— Potatoes undergo some changes in storage. Not only do they lose water and decrease in weight but they increase in sugar. When sprout- ing commences, the potato becomes sweeter, due to the con- version of starch into sugar by the enzyme diastase. The most vigorous buds are the terminal ones. The tip of the main sprout grows upward. The underground stems bear tubers at their ends. These will not tuber if brought to the Hght but will develop into ordinary green-leafed shoots. Physical Composition of Potatoes.- — In all varieties the cells of the cortex are much smaller than those of the medulla. In general, potato varieties are characterized by their cellular density and can be grouped accordingly. The groups are not, however, clear-cut. Cellular density is an important factor to consider in the breeding of potatoes for SOLANACE^ 579 table use, or for the industries. For table use, only those tubers should be selected which have small cells (high density), and for starch factories only those with large cells (low density). Even with the same amount of starch in two varieties, it is found that the large-celled one is the more valuable to the "starch industry, due to the fact that in the small-celled varieties a larger number of the cells remain intact and do not give up their starch in the starch-removing process, while with the large-celled varieties fewer starch cells escape being broken up. In France, it was found that rich, compact (heavy) soils produced tubers with a low cellular density, while the Hghter soils produced tubers with small cells and high density. Chemical Composition of Potatoes.^ — A number of analyses of potatoes have been made in this country and in Europe. Gilmore gives the results of a number of these in the follow- ing table: Source ■^°- °* ^°- °^ analyses j varieties Cornell ! 43 ' 4 Maine 16 4 U. S. all sources 136 France: Coudon and Boussard 7 7 Coudon and Boussard ' 8 8 Coudon and Boussard 7 | 7 Coudon and Boussard 12 I 12 Protein Starch Quality 1.899 17-356 Very good 2.170 18.037 Very good 2.200 18.400 2.676 ir.798 Very good 2. 41 1 13.218 Good. 2.365 14.118 Passable. 2.090 16.047 Poor. Water and nitrogen increase from the outer to the inner zones, while the starch content decreases. The following table showing composition of the potato is from East: 580 BOTANY OF CROP PLANTS Variety Zone [ Rural Cortical I New Yorker Outer Med. [ No. 2 Inner Med. Carman No. 3 .. . . Cortical Outer Med. Inner Med. Dry matter, per cent. Total N, fresh basis, per cent. Total N. dry basis, per cent. 20.9s 0.46 2. 20 18.46 0.47 2.56 14.04 0.45 i-^i 22. 20 0.49 2. 23 19.41 0.51 2.63 14.92 0.52 3-49 This table shows that the dry matter decreases from the outside to the inside of the tuber. The nitrogen content shows an increase, on dry basis, from the outside to the center, although on a fresh basis there seems to be no regu- larity of percentage, probably due to variability in water content. The inner cells of the cortex contain a much larger amount of starch than those of the external medulla, which in turn contain considerably more than the cells of the inter- nal medulla. The outer cells of the cortex which are removed with the skin (in peeling) are comparatively low in starch. Starch and Sugar. — Potato starch grains are egg-shaped or nearly spherical with eccentric markings, and with the hilum near the small end. Some varieties of potatoes are abundantly supplied with large starch grains with infre- quent small ones, while in other varieties the reverse is the case. No correlation has been found between the size of the starch grains and the size of the tuber or its total starch content. In general, the early varieties contain large starch grains while the late varieties contain a larger proportion of small grains. Starch-grain formation is very slow. At first, many small grains are found, most of which later increase in size. This increase in size begins much sooner in early varieties than in late varieties. SOLANACE^ 581 In addition to starch, potatoes contain noticeable amounts of sugar. The average quantity is not far from 0.35 per cent. This sugar is lost in starch-making, but is utiHzed in the manufacture of alcohol. 'Mealiness." — In estimating cooking quahty of potatoes, meahness is the most important consideration. Mealiness depends quite largely upon the amount of starch in the cells. When boiled in water, the starch grains expand and coalesce. If there is sufficient starch, as is usually the case in the cortex, this expansion ruptures the cell walls, freeing their contents and producing mealiness. A deficiency of starch, as is usually the case in the cells of the internal medulla, produces swelling insufficient to rupture the cell walls; hence, soggi- ness results. As has been shown, the different zones of the potato vary considerably in starch content, the cortex being highest, and the internal medulla lowest. If the internal medulla is large and has branches extending into the external me- dulla, the tuber is likely to be hard and soggy when boiled, and to contain zones or parts which will not mash uniformly and readily. The external medulla is usually well stocked with starch. When this is the case, and when the starch is distributed uniformly, leaving no "water areas," a high degree of mealiness can be expected in the boiled tubers, a condition necessary for high table quahty in America. Quality of Potatoes.— The standards for table quality in potatoes vary somewhat in different countries. The more noticeable differences seem to be between France and the United States. East notes that most of the potatoes which he examined, imported from France, had a yellow flesh, a strong flavor, and were firm and soggy after boiling. In France, potatoes are commonly cooked by frying in deep fat. For this purpose, a potato yellowish in color which holds its 582 BOTANY OF CROP PLANTS form, and is, as a result, more or less soggy after boiling, is preferred. These characteristics are usually found in po- tatoes which are low in starch and high in protein. In the United States, on the other hand, where probably nine-tenths of the potatoes eaten are boiled, a white, floury, starchy po- tato which is mealy and dry when cooked is demanded for table use. In Germany, table potato standards are more Hke those in the United States. In general, it is considered that for table use in this country potatoes must contain about 17 per cent, or more of starch. As a result of experimentation with 15 American varieties. East says: "It is quite evident then that potatoes having as far as possible a homogeneous flesh and containing as large an amount as possible of cor- tical and outer medullary layers in proportion to inner med- ullary layer, should be of the finest quahty." Degree of Maturity and Quality .^ — Analyses in the United States have shown that the "greater part of the total nitro- gen is developed early in the growth of the tuber, while the starch is stored up later." It was also found that " the starch grains of immature tubers are small in size and few in number." Tubers increase in desirability with maturity. Degeneracy of the Potato. — The "running out" of potatoes is a common observation. New varieties are put on the market, are very productive for a varying number of years, then they usually begin to "run out" or degenerate. In Colorado, varieties in the mountain districts do not tend to run out, or only very slowly, the tendency apparently being easily overcome by seed selection, while in the Greeley district, on the plains, at an altitude of 4,600 feet, the sexual tendencies and consequent degeneracy seem to overcome other influences, such as selection. At Svalof (Sweden) the opinion is held that in a variety of potatoes "there is no period of old age." On the other hand, degeneracy is be- SOLANACEyE 583 lieved to be the result of "factors which hinder the normal development of the plants and tubers or invite disease." Stewart recently describes forms of degeneration known as leaf-roll, curly-dwarf, mosaic and spindling-sprout. He found that the progeny of plants with normal foliage and high yield may very suddenly degenerate into dwarfish plants affected with the above-mentioned diseases. The leaf-roll, curly-dwarf and mosaic troubles are passed from generation to generation by means of the tubers. The nature of spindling- sprout is not this well known. The observations are significant in that they show that seed selection may not always insure against "running out." It is claimed by the Svalof investigators that more vigorous seed tubers are pro- duced in cool, moist conditions than in hot, dry regions. This view is also held by Fitch who worked in Colorado. The cause of this increased vigor is another question. It may be due to a well-developed vascular system in the tuber or an abundance of diastase at the sprouting season. Investi- gators express the view that "where suitable sorts are used, and where suitable tubers of these sorts are utilized for seed- ing purposes each year, the standard of a variety may be maintained indefinitely under all favorable conditions of soil and climate." Hence it seems that the inherent tendency to degenerate is perhaps no stronger in potatoes than in other crops, but that they are more widely and strongly influenced by environmental conditions than are most crops. It is re- ported that at Svalof the variety Dala, introduced about 150 years ago in the province of Delarne, is still one;^of[the best sorts grown there. Environmental Relations.— The potato is a native of the high, cool regions of Mexico and South America. In the United States it thrives best in a cool, moist climate as is evidenced by the fact that the five leading ^potato States 584 BOTANY OF CROP PLANTS touch the Canadian border. It is well adapted to elevation up to 8,000 feet in the Central Rocky Mountains. Smith has shown that the potato makes its best development in those sections of the country where the mean annual temperature is between 40° and 5o°F., and where the mean for July is not over 7o°F. The plant is grown on both heavy and light soils, but the latter are preferred; upon these, the plant is less subject to Fig. 238. — Percentage of the world's supply of potatoes produced in the different countries in 1914. disease, the tubers are of better quahty and smoother, and come to maturity more quickly. Uses of Potatoes. — Potatoes are put to the four following chief uses: (i) human food; (2) commercial starch; (3) stock food; and (4) alcohol. Potatoes rank second to the cereals in importance as a food of northern peoples. They are fed to all classes of stock, especially hogs. In the dried state, they have been fed, in Germany, to cattle and horses with good results. Potato Starch: — The potatoes are first soaked for several hours in water, then washed, and finally reduced to a pulp I SOLANACEiE 585 by rasping machines. The pulp is passed through sieves, which separate the fiber from the Hquor containing starch. The liquor is allowed to stand, and during this time white starch settles in layers at the bottom of the receptacle. The starch is drawn off, purified by allowing it to run over tables, similar to those used in the purification of corn starch (page 184), and finally dried. "Culls" are profitably employed in starch manufacture. Alcohol.- — In Germany, the potato is used extensively for alcohol manufacture. In this country, it is too expensive for this purpose. The process of converting the starch to alcohol is very similar to that used in the manufacture of alcohol from corn starch. Production of Potatoes.- — The world's output of potatoes in 191 2 was 5,872,953,000 bushels. Of this amount, Ger- many produced 1,844,863,000 bushels, or about 31 per cent, of the total. Russia proper ranked second with a production of 925,775,000 bushels. France third with 552,074,000 bushels, and the United States fourth with 420,647,000 bushels. The five leading potato States in 191 5 were Minne- sota, Wisconsin, New York, Maine and IMichigan. SOLANUM MELONGENA (Eggplant, Guinea Squash) Description. — This species is an annual, erect, branching herb, finally becoming subwoody, 2 to 3 feet tall, woolly or scurfy, and spiny. The leaves (Fig. 239) are large, 6 to 9 inches long, sinuately lobed, ovate or ovate-oblong, thick, becoming almost smooth above but remaining densely hairy beneath. The flowers are soHtary or in small clusters in the axils of branches; the calyx is woolly or spiny, the corolla purplish and pubescent (Fig. 239). Parthenocarpy has been observed in this species. Artificial pollination is practiced 586 BOTANY or CROP PLANTS to insure fruit production. The fruit is a berry, 3 to 6 inches in diameter, smooth, and varying in color (Fig. 239). Egg- plant is a native of India. All cultivated varieties require high temperatures. They are usually transplanted. They are used exclusively as a table vegetable. Fig. 239. — Egg plant (Solanum melongena). A, mature fruit; B, leaves; C, single flower. Types and Varieties.— Bailey has divided the eggplants into three varieties, as follows: I. S. melongena var. esculentum (Common Eggplant). — The plants are tall and stout, the leaves large and thick, and the fruit large and usually spherical or oblong. There are forms in this group with purple fruit (Black Pekin, New York SOLANACE^ 587 Improved, Giant Round Purple) and others with white or striped fruit (White Chinese, Long White, White Egg). 2. S. melongena var. serpentinum (Snake Eggplant). — The plants are medium to tall, the leaves large, and the fruit long and slender. 3. S. melongena var. depressum (Dwarf Purple Eggplant). — The plants are small, weak, and spreading, the leaves small, the flowers small, and the fruit small to medium, pear- shaped, and purple (Early Dwarf Purple). LYCOPERSICUM (Tomato) Habit of Growth, and Stems. — The tomatoes are annual or short-lived perennial, coarse, branching or feebly climbing herbs, that vary in size and form with the species," climate, and methods of culture. The upright growing tomatoes {L. esculenlum var. validum), have a low, stiff, and erect growth form. L. esculenlum var. grandifolium is a tall sort with a few large, entire leaflets. In the currant tomato {L. pimpinelHfolium) , and cherry tomato (L. cerasiforme), the branches are usually w^eak and even trailing in habit. The pear tomato (L. pyriforme) has an erect and strong habit of growth. Roots.- — The root system of tomatoes is fibrous and not extensive. It does not penetrate far into the soil and is usually short-lived. In the transplanting of tomatoes from the seed bed to the garden, it is the practice to allow the seedHngs to wilt before they are reset. Under these conditions the fine, tender rootlets, and root hairs are largely destroyed, but the plant promptly throws out a vigorous cluster of new ones. In fact, the new set of roots possesses greater vigor than those on a seedling that has not been allowed to wilt; in the latter case the roots arc not injured beyond recovery, and it ap- 588 BOTANY OF CROP PLANTS pears that their recovery prevents the prompt development of new ones. Leaves. — The leaves are usually alternate, always com- pound, odd-pmnate, and petioled. In all tomatoes except L. escidentum var. grandifolium and possibly L. pimpinelli- folium, the leaflet margin is toothed or lobed. Inflorescence and Flowers. — The flowers are commonly in raceme-like cymes, or in racemes (as in currant tomato). However, even in the currant tomato the racemes are often branched at the tip. The flowers are perfect, regular, and pendant. The calyx is five- to six-parted; the segments are linear or lanceolate, persistent, and increase in size with the development of the fruit. The corolla is rotate or wheel- shaped, 'cleft into usually five, sometimes more, lobes; the tube of the corolla is short. There are five stamens (some- times more) attached to the corolla tube; the filaments are very short, and the anthers open by a longitudinal slit on the inner side; they are elongated, connate or connivent. There is one pistil bearing a single style and an ovary, which is usually two-celled (more than two-celled in cultivated tomatoes) and has a central, fleshy placenta. Pollination, Fertilization, and Development of the Fruit.^ — In the maturing of the flower, the style elongates and pushes the receptive stigma through the tube formed by the anthers. In some instances, this elongation occurs prior to the dehisc- ing of the anthers, hence eliminating the possibility of self- pollination. Sometimes the anthers shed pollen at the time the stigma is pushed upward, and in the growth of the stigma it rubs against the dehiscing surface of the anthers. Stigmas remain receptive for several days. However, it is known that greenhouse tomatoes do not set fruit well unless arti- ficially pollinated, as is commonly done by jarring the plants at the time of anther dehiscence. Natural cross-pollination seldom occurs. SOLANACEiE . 589 Extensive experiments made l)y Fletcher and Ciregg with greenhouse or forced tomatoes showed that self-fertihzed blossoms set fruit as well as cross-fertilized ones. Further- more, there was practically no difference in the appearance or weight of the fruit, and no difference in the number of cells. Parthenocarpy. — This phenomenon is not at all uncommon in tomatoes. By this is meant the ripening of the fruit without the fertilization of the ovules. Such fruits, of course, possess no germinative seeds. Abnormal Tomatoes. — Munson has found, in crossing tomatoes, that the amount of pollen placed on the stigmas affects the size of the fruit. Two stigmas in the same flower cluster were given different amounts of pollen: one abun- dant pollen, the other lo to 20 grains. With plenty of pollen, normal fruit resulted, while with scanty pollen, small and deformed fruit resulted. In the first case, there was abundant seed, while in the latter, only a few seeds. One- sided tomatoes result when pollen falls upon one side of the stigma only. It is undoubtedly commonly true that small and irregular tomatoes are caused by an insufiicient supph- of pollen. The Mature Fruit. — The fruit is a true berry (Fig. 240). The wild form of our common garden tomato (S. esculentum) has a two-celled fruit with a rather dry placenta. The cells are definite in both number and shape. Cultivated forms of the common garden tomato have a number of cells in the fruit; they are indefinite in both number and shape, and the placenta is exceedingly fleshy. The fewest celled fruits are considered nearest the original type. The pear and cherry tomatoes both have two-celled fruit. The calyx is persist- ent, adhering to the base of the fruit. The fruit varies in shape, color, and smoothness of surface. The seeds are numerous and small. 590 • BOTANY OF CROP PLANTS Geographical. — All the species in this genus are natives of South America. Dunal, in DeCandoUe's Prodromus, gives lo species of Lycopcrsiciim; this number is reduced, however, by some writers. Tomatoes are warm season "vegetables" that require transplanting in central and northern latitudes. Important Species and Varieties, — There is a difference of opinion whether to consider certain forms of tomatoes species or only varieties. For example, Bailey recognized Fig. 240. — Cross-section of mature fruit of cultivated tomato (Lycopersicon esculentum) . but two cultivated species of Lycopcrsicum: L. esculentum, the common tomato, and L. pimpinellifolium, the currant tomato. L. esculentum is, according to Bailey, divided into the following varieties : 1. L. esculentum va.r. vulgare, garden tomato. 2. L. esculentum var. cerasiforme, cherry tomato. 3. L. esculentum var. pyriforme, pear or plum tomato. 4. L. esculentum var. validum, upright tomato. 5. L. esculentum var. grandifolium, large leaf tomato. L. pimpinellifolium is not subdivided. On the other hand, Tracy regards as distinct species: L. pimpinellifolium, L. SOLANACE^ 591 cerasiforme, L. pyrijorme, and L. csculcnlum, including under the last the varieties viilgare, validum, and grandijoliimi. The above types of tomatoes may be artificially distin- guished by the following key; in all instances cultivated forms are understood. Key to Types of Cultwated Tomatoes Fruit in long racemes or branched clusters; berries red, currant-like, Currant, German, raisin or grape tomato. Fruit in short racemes or branched clusters. Plants low, stiff, and erect, having much the appearance of a potato plant; leaves small, curled, U pright tomato. Plants taller, the branches weaker and more spreading. Leaves very large, about two pairs of almost entire-margined leaflets, Large-leaf tomato. Leaves of medium size, numerous j)airs of leaflets the margins of which are toothed or lobed. Fruit pear-shaped, Pear tomato. Fruit globular or angular, not pear-shaped. Fruit globular, smooth, red or yellow, from H to ^4 inch in diameter, two-celled, Cherry tomato. Fruit varying somewhat in shape, surface, and color, larger than preceding, many-celled. Common garden tomato. The common tomato (var. vulgare) has undergone consid- erable modification as the result of cultivation. As compared with the small two-celled fruit, with thin walls and a dry placenta, and in some instances with distinct grooves on the surface, the cultivated forms are larger, many-celled, the walls and placenta are thick and fleshy, and the fruit surface smooth. There are three general groups of the common tomato: fruit angular, fruit apple-shaped, and fruit oblong. The cherry tomato (var. cerasiforme) has small globular, red or yellow two-loculed fruit. The pear tomato (var. pyriforme) has small red or yellow, two-loculed pear-shaped fruit. The upright tomato (var. validum) looks much like the potato plant in its growth habit. The large-leaf tomato 592 BOTANY OF CROP PLANTS (var. gra ndifolium) , of which the Mikado may be taken as a type, is distinguished from the other varieties by its large leaves with only a few (normally two) pairs of leaflets. Closely Related Forms. — The husk tomato {Physalis pnhescens) and the strawberry tomato (Physalis piibcsccns and P. alkekengl) are distinguished from Lycopcrsicum spp. in that the calyx becomes enlarged, inflated, and en- tirely covers the small berry. The fruit is esteemed by some for preserving, or making pies, or for eating raw. The tree tomato {Cyphomandra belacea), a tropical plant, has a fruit similar in taste, at least, to that of the common tomato. This plant also belongs to the Solanacere, but may be distinguished from Lycopcrsicum by its woody habit of growth. History. — The tomato is still found in the wild state in South America. The Spanish explorers carried the fruit to southern Europe where it was used as a food long before it was eaten by the people of northern Europe. It was early known in England and America as the ''Love Apple. " A prejudice against the tomato existed for a long time, no doubt due to its alliance with the nightshades. Now, however, it is a favored article of diet, and from 500,000 to 600,000 acres are devoted to its growth annually in the United States and there are as many as 175 different varieties offered by seeds- men. Uses.- — Tomatoes are commonly used, fresh or canned, as a table vegetable. Large quantities are made into catsup. Such varieties as Red Plum, Yellow Plum, Red Pear-shaped, Red Cherry, and Burbank's Preserving are used quite ex- tensively for pickling. CAPSICUM ANNUUM (Peppers) Description.- — This species is either an annual or biennial herb, 2 to 5 feet tall, and sometimes partly woody at the base. In temperate regions, the plant is cultivated as an annual, while in warmer climates it is often biennial. The leaves are S()LANACE^> 593 ovate and entire. The flowers (Fig. 241) are solitary, or in twos or threes. The calyx is iive-lobed, truncate, obcon- ical, cup-shaped or funnel- form. The corolla is white, rotate, usually Iive-lobed, with the lobes valvate. There are five stamens, some- times six or seven, attached near the base of the corolla; the bluish anthers dehisce longitudinally. The ovary is usually two-celled, rarely three-celled, and bears a thread-like style, and numer- ous ovules. The fruit (Fig. 242) is a berry, red or green in color, and short cylindrical or globular in shape are many seeds in each fruit. corolla lobes 'Slamen ~cal\jx lobe 2 -celled ovar'j Fig. 241. — Median longitudinal section of pepper flower (Capsicvim annuum). X 2. There J Fk;. ^4: Cri)ss and lcn"th\ ■ sections of the fruit of pei)pcr (.Capsicum annuum). 38 594 BOTANY OF CROP PLANTS Geographical. — This species has iie\er Ijeen found wild. But it is quite well established that the entire genus Capsifum had its origin in tropical America. Fig. 243. — Fruits of peppers (Capsicum annuum). A, Oxheart (C. annuum cerasiforme) ; B, Cherry (C. annuum cerasifera) ; C, Celestial (C. an- nuum abbreviatum) ; D, Chilli (C. annuum acuminatum); E, Long Cayenne (C. annuum acuminatum); F, Long Yellow (C. annuum longum); G, tabasca (C. annuum conoides) ; H, Sweet Spanish (C. annuum grossum) ; I, Ruby King (C. annuum gros.suin); J. Bell (C. annuum grossum); K, Squash (C. annuum grossum). (After Irish.) The temperature requirements of peppers are similar to those of eggplants and tomatoes. Their season of growth is so long that they are unable to SOLANACE/E 595 produce a full (.•i(>[) hcfort- liosl, ixiopl in llir Soullurii Slates, unless starU'il under glass. Other Species. — The only other species of Capsidim oi any importance is C. fnitescens. This is a shrubby perennial 6 to lo feet high. Its fruit does not ripen well in northern latitudes. The fruit is red, small, and is often called "bird pepper." Types. — Irish, in his excellent monograph of the genus Capsicum, places the numerous commercial varieties into seven types or botanical varieties (Fig. 243). The following key to these types is taken (verbatim) from this work. Key to Botanical Varieties of Capsicum Annuum Fruit oblong-linear. Calyx usually embracing base of fruit. Fruit usually less than 1^2 inches long; peduncles about as long or longer, C. annuum conoides (Coral Gem, Tabasco, Cayenne, Orange-red Cluster). Fruit usually more than 1)^2 inches long; peduncles shorter. Lea\-es and fruit fascicled; fruit erect, C. annuum fasciculalum (Red Cluster, Yellow Cluster). Leaves and fruit not fascicled, C. annuum acuminatum (Chilli, Long Cayenne, Nepal Chili). Calyx not usually embracing base of fruit, except in the Ivory Tusk variety, C. annuum longum (Black Nubian, Long Red, County Fair, Cardinal, Long Yellow, Ivorj- Tusk). Fruit oblate or oblong, truncated, deeply lobed, furrowed and wrinkled; fiesh mild, 3^12 to ig inch thick, C. annuum grossum (Monstrous, Sweet Spanish, Bell, Sweet Mountain, Golden Dawn, Ruby King, Brazilian Upright, Golden Upright, Squash). Fruit subconical, ovate or elliptical, slightly longer than broad, J?4 to 2 inches long; calyx not embracing base, C. annuum abbrevialum (Celestial, Etna, Kaleidoscope, Red Wrinkled, Princess of Wales). Fruit generally smooth, oval, spherical, cherry or heart-shaped, % to iJ'2 inches in diameter; calyx seated on the base, C. annuum ccrasiforme (Little Gem, Cherry, Oxheart). Composition. — All varieties of pepper are more or less pungent. The principle which imparts the pungent taste is a crystalline nitrogenous compound called capsaicin. In the smaller j)eppers (Coral Gem, Tabasco, Chilli, Cayenne 596 BOTANY OF CROP PLANTS Cherry) the pungency is in the pericarp as well as in the pla- centa and seed. In larger varieties (Squash, Bell, Sweet Mountain), the pungent taste is located for the most part about the seeds, while the fleshy pericarp is ''mild." Uses. — Medicinally, the red pepper is used in a great variety of ways. Probably its most important use is as a condiment, Cayenne Pepper being the common form. This is made by grinding up the entire fruit to a fine powder. Pepper sauce is the unground fruit preserved in brine or strong vinegar. Tabasca Pepper and Tabasca Catsup are examples of this. Chilli con carne is a mixture of small, finely ground peppers and meat. Peppers are commonly used in tamalas, also in pickles and salads, while bell-shaped and squash varieties are used as mangoes. Some varieties, such as Little Gem and Prince of Wales, are grown for orna- mental purposes. NICOTIANA (Tobacco) Habit- — Most representatives of this genus are tall, stout herbs. Several (as N. glauca and A^". tomentosa) grow to a height of 10 feet or more. S. wigandioides is half-shrubby. They are annual or perennial in habit, and for the most part sticky-pubescent; they have a strong odor, and narcotic, poisonous properties. Leaves. — The leaves are simple, alternate, mostly large, entire or wavy along the margin, petioled (in A^. glauca), or sessile and decurrent. Inflorescence and Flowers.^ — The inflorescence is a terminal raceme or panicle. The flowers are large and vary in color: white, yellowish, yellowish-white, greenish, purpHsh, or rose. The calyx is synsepalous, five-cleft, and usually persists in the fruit. The corolla is salverform or funnelform, five- lobed, and the tube is longer than the hmb. There are five SOLAN ACEiE 597 stamens attached to the corolla tube; the filaments are slen- der, and the anthers split lengthwise. The two-celled ovary bears a single, slender style, and a capitate stigma. Fruit.- — The fruit is a two-celled capsule bearing numerous very small seeds; it splits into two or four valves at maturity. Geographical Distribution and Economic Importance. — The genus includes about 50 species, mostly of the American tropics. A number of species are grown for ornamental pur- poses. N. tahaciim (tobacco) is the only one of great commer- cial importance. NICOTIAN A TABACUM (Tobacco) Habit, Roots, Stems.— The comnion tobacco is a strong annual plant, 3 to 5 feet tall. The root system is quite ex- tensive and fibrous. The American varieties bear large, thick stems which are hairy and sticky. In tobacco culture it is customary to "top" the plants, that is, remove the iiower stalks, so that a considerable portion of the food supply which would normally go to flower and fruit production may be directed to leaf grow^th. Topping stimulates the produc- tion of ''suckers" (new shoots). They must be removed before reaching any great size, as the quality of the leaves is damaged by their growth. The "one-sucker" type of tobacco is one that throws out one or only a few suckers. Leaves. — There is great variation in the shape, color, tex- ture, and number of leaves. In cigar-wrapper tobaccos, the leaves are thin, fine in texture, and small-veined. The leaves of plug and pipe tobaccos are usually coarser, thicker, and tougher. The leaves are sessile, decurrent, and either narrow^ or broad, most commonly lanceolate or ovate, and pointed. The number of leaves on a plant, which is, of course, important commercially, is different in the various types and also varies considerably from plant to plant in the 598 BOTANY OF CROP PLANTS same type. In the Sumatra cigar- wrapper tobacco the leaves range from i6 to 30, in the White Burley plug tobacco from 10 to 18, and in the Zimmer Spanish cigar-filler tobacco from 14 to 20. Tobacco plants are sometimes grown in the shade of tents, which condition makes a larger and thinner leaf with less vascular tissue. The leaf is thus improved for wrapper purposes. The chief effect of shade is to reduce the rate of transpiration. There is evidence that transpiration rate is the important factor determining the development of vas- cular tissue. ''Grain'' in Tobacco Leai^e^.—" Grain" of tobacco appears as small pimple -like projections or papillae over the cured leaf. The papillae vary in size from about i millimeter to microscopic dimensions. Each grain body consists of from one to several leaf cells filled with crystalline substance. The grain is composed chiefly of calcium, with some potas- sium and magnesium, in combination with citric and malic acids. Grain of tobacco is developed during the process of curing and fermentation. It is a character that the buyer takes into consideration when he selects tobacco. Inflorescence and Flowers.— The inflorescence is a terminal panicle. TYie flowers (Fig. 244) are about 2 inches long, and pink;Vellow, purple or white. The tubular or bell-shaped calyx is four- to five-cleft. The tube of the corolla is swollen, its lobes spreading and pointed. Pollination and Fertilization- Tobacco flowers bear nec- taries and are visited by insects. Hence, cross-pollination is probably somewhat frequent. Moreover, observations and experiments show that the flowers are self-fertile— that they will produce viable seed when close-fertilized. The earlier blossoms of an inflorescence are more commonly close-fertilized than are the later ones of the same inflores- so LAN ACE. E 599 cence. That the tobacco j^lant is, in all probability, natu- rally close-fertilized, is borne out by the fact that self-fertili- zation (inbreeding) under control has not resulted in a loss of vigor. Fig. 244. — Tobacco (Nicotiana tabacum). .4, flower; B, \nstil; C, corolla cut open and spread out flat; D, cross-section of young fruit; E, lengthwise section of young fruit. (After Slrashiirger.) Fruit." — The fruit (Fig. 244) is a two- to four-valved cap- sule, bearing numerous small seeds. A single plant may produce as many as a milHon seeds. Geographical. — This species is indigenous to tropical South America. Its varieties are now in cultivation throughout subtropical and even temperate climates. It occasionally escapes from cultivation and runs wild. It is grown commercially only in the humid sections of this country. 6oo BOTANY OF CROP PLANTS Closely Related Species.- — There are a number of species of Nicotiana which resemble N. tabacum somewhat, and there are several species belonging to other genera besides Nicotiana that go by the name "tobacco." N. rtistica is a "wild tobacco" that was cultivated by the Indians. It is a tall annual with petioled leaves. N. quadrivalvis is another plant cultivated by the Indians for tobacco. It is native to the region extending from Texas to California and Oregon. N. persica yields Persian tobacco. "Australian tobacco" is the leaf of Duboisla hopwoddii, a species of Solanacea. "Indian" or "wild tobacco" is a name often given to Lobelia inflata, the dried leaves and tops of which are officinal. It is a member of the bellflower family, CampanulacecE. Arnica alpina, a composite, is sometimes known as "moun- tain tobacco." The most popular ornamental Nicotiana is N. alata. In it the flowers are white, open at night and closed in the daytime. Types and Varieties.- — There are two general types of tobacco grown in this country: 1. Cigar type, the leaves of which are made into cigar wrappers, binders and fillers. The leaves are thin and of fine texture. Common varieties are Sumatra, Connecticut Havana, Connecticut Broadleaf, Cuban, Zimmer Spanish, and Little Dutch. 2. Export and manufacturing type, the leaves of which are used to make smoking tobacco, chewing tobacco, cigarettes, and snufT. The leaves, as compared with those of the pre- ceding type, are thicker, tougher, and of coarser texture. Popular varieties are White Burley, North Carolina Bright Yellow, Maryland Smoking, Yellow Mammoth, Pryors and Orinocos. Export and manufacturing tobaccos are pro- duced on soils and in sections of the country different from the cigar types. The physical and chemical properties of the soil have a marked influence on the quahty of the tobacco leaf. Light, well-drained soils, in which there is not too much organic matter, produce a leaf of mild flavor and fine texture. On the other hand, heavy, rich soils produce a leaf of stronger flavor and coarser texture. Composition. — The tobacco plant is a heavy feeder. It SOLANACE^ 60I removes large quantities of nitrogen, potash, and phosphoric acid from the soil. Consequently, the plant is rich in these valuable plant nutrients. In fact the leaves and stalks make excellent fertilizers, and are so used in tobacco sections. Curing Tobacco.^ — This process consists in removing the moisture in the leaves and stems in such a manner as to produce a uniform color and texture in the leaves. Artificial heat was first employed in the curing of tobaccos in 1812. Wood fires were used up to the year 1828, about which time, flues, and charcoal fires came into use. Flue-curing entirely replaced charcoal fires in 1865. Flue-curing produces a bright yellow leaf. The green tint is obtained by harvesting the leaf before it is fully ripe. The dark export tobaccos are cured with open hard-wood fires. Light tobaccos may be air-cured, and such are used for pipe smoking, and cigarettes. White Burley tobacco, so highly prized for twist and plug chewing tobaccos, is usually air-cured. The yellow and mahogany tobaccos are cured by flues. The process takes about four days. The broad leaf and Havana seed leaf varieties of the Connecticut Valley are air-cured. They are domestic cigar tobaccos. Curing is often carried on in specially constructed barns with horizontal ventilators. It usually takes about two months to air-cure tobacco, and less time if artificial heat is used. After the leaves have been left hanging for a long time, they are packed closely in boxes, where they are left undisturbed for several months. When warm weather sets in, a process of fermentation is set up in the cases, during which process certain important changes take place. Fermentation may be brought about after a shorter period of drying than is used in the preceding method, by placing the leaves in piles in a warm, moist at- mosphere. When the temperature reaches 125° to i3o°F., the piles are opened and heaped up again. The piles are 6o2 BOTANY or CROP PLANTS thrown down and remade a number of times, until the leaves are ready for the market. During the fermentation the leaf undergoes a number of changes such as a decrease in nicotin, an increase in alkaline reaction, in ammonia, and nitrate, a loss of water and sugar, and a change in the texture, color and flavor. It is not known positively whether fer- mentation is a result of oxidation by free oxygen of the air, or of bacterial activity, or is due to the action of enzymes. The Tobacco Industry. — From colonial days the tobacco industry has been an important one in this country. It Is interesting to note that tobacco was made legal tender in 1732 in Maryland, where a' pound was i penny, and where it was used for the "payment of all debts, including customs, dues, salaries of State officers and ministers of the gospel." In 1777 the tax levy for the county and city of Baltimore was 172 pounds of tobacco per poll. Virginia and Maryland were long the only tobacco-pro- ducing States. The industry has now spread to other States, and the production in 1915 is shown in the following table : Tobacco: Acreage, Production, and Total Farm Value, BY States, 1915 State Acres Kentucky 440,000 North Carolina .-,... j 320,000 Virginia 192,500 Ohio 93,700 Tennessee '. 92,900 Pennsylvania 31,400 South Carolina j 65,000 Wisconsin j 41,000 Connecticut 22,200 Maryland 22,000 All other States 47, 700 United States 1 1,368,400 Pounds Farm value Dec. I, dollars 356,400,000 23,799,000 198,400,000 22,221,000 144,375,000 13,571,000 84,330,000 7,590,000 69,675,000 4,990,000 42,390,000 3,900,000 37,700,000 2,639,000 36,900,000 2,214,000 29,907,000 3,095,000 16,280,000 1,384,000 44,030,000 12,638,000 1,060,387,000 96,041,000 ^ y^ ^ <5Vl \ ' "^ ^^=^— \-9^ (0 V j3-v--^*^r«v. h \ ^^■^'^^'"•^ / /^ ^5^ Z t- z LJ CO ^<» 'iX ••■•'T <^ a: Q. CO UJ rr a ;/, cc UJ () > -* H a: < o « - O lU n$ oj an the 'ens — st\jks receptacle . ' scale -ovar\j ■ ovar\j wai CNKile Fig. 254. — Jerusalem artichoke (Helianthus tuberosus). A, lengthwise section of head, X i; B, ray flower, X 6; C, disk flower, cut lengthwise, X 6. {A after Baillon.) varies in shape from flat to convex or conical. The recep- tacle is naked or there are chaffy scales subtending the flower; its surface is smooth, pitted, or honeycombed. The involu- cral bracts also vary widely in shape, from narrow and spine- like to broad and leaf-like; they occur in one or more series. COMPOSITE 627 Flowers. — The flowers may be perfect, polygamous, monoecious or dioecious. There are two sorts of flowers in the composite family: (i) Disk or tubular, and (2) ray or ligulate. Disk Flowers (Fig. 254, C). — These are perfect and regular and make up the so-called disk of the composite "flower." For example, the disk of the "sunflower" is the center. The calyx is modified, taking the form of a few or large number of bristles, awns, scales or teeth; this modified calyx is termed a pappus. In some instances, the pappus is entirely wanting. It is attached to the apex of the inferior ovary. The corolla is tubular and five-lobed. The five stamens are attached to the corolla and alternate with its lobes; the anthers are united into a tube. In one genus (Kuhnia), the anthers are distinct or nearly so. The anthers are often appendaged at the apex and sometimes caudate or sagittate at the base; pollen grains are spherical, often rough or prickly. There is a single pistil, an inferior one-celled and one-seeded ovary, and a single style which is entire (in sterile flowers) or two- cleft at the apex; the style branches are often tipped with appendages. Ray or Ligulate Flowers (Fig. 254, B). — These are usually imperfect and irregular. They have a pappus and a strap- shaped corolla with either a long or short tube. The composite family is divided into two large groups, the Ligiiliflorce and Tubuliflorce. The dandelion, chicory, and lettuce are representatives of the former, and sunflower, Jerusalem artichoke, daisy, fleabane, aster, and goldenrod typical members of the latter group. In the Liguliflorce, ligulate or strap-shaped flowers are the only sort present; in these, the flowers are perfect and consist of five stamens with their anthers united into a tube, a one-celled, one-seeded ovary, a single style, and a two-lobed stigma; the pappus may 628 BOTANY OF CROP PLANTS be present or wanting. In the Tulmlijlorce, there are both disk and ligulate flowers, the former occupying the center of the head, while the hgulate ones are at the margin of the receptacle, and are called ray flowers. In the Tubiliflorce, the ray or ligulate flowers are very frequently pistillate. In both types of flowers, the fruit (achene) is one-seeded and indehiscent. The pappus is usually persistent at the apex of the fruit, serving as a means of dissemination by the wind. Key to Important Genera Flowers with ligulate corollas only; flowers perfect. Pappus of plumose bristles, Tragopogon (salsify). Pappus not plumose. Pappus of mere chaffs or these reduced and united into a crown, dehor iuni (chicory) . Pappus of capillary bristles. Achenes flattened, Lactuca (lettuce). Achenes not flattened, Taraxacum (dandelion). Flowers with tubular corollas or none, or only the ray flowers with ligulate corollas. Anthers long- tailed at the base and with long appendages at the tip; heads large; rays none, Car dims (thistle). Anthers not tailed at the base; flowers tubular only, or tubular and ligulate. Receptacle naked. Ray flowers yellow; involucral bracts scarcely imbricated, Arnica. Ray flowers never yellow; involucral bracts well imbricated. Bracts of involucre imbricated in several series, Aster. Bracts of involucre in but one or two series, Erigeron (fleabane). Receptacle chaffy. Bracts of involucre foliaceous, Hclianlhus (Jerusalem artichoke and sunflower). Bracts of involucre dry, thin, and papery. Receptacle chaffy, Achillea (yarrow). Receptacle not chaffy, naked, or sometimes hairy. Raj' flowers present. Chrysanthemum. Ray flowers none, Artemisia (sage and wormwood). COMPOSITE 629 LACTUCA SATIVA (Garden Lettuce) Description. — Common garden lettuce is a tall, annual leafy herb, with a milky juice. There is thrown up from a short stem early in the season a cluster of leaves varying considerably in shape, character, and color, in the different varieties. Later in the season, a "seed stalk" is sent up. Tracy found that, at Washington, D. C, the first appearance Fig. 255. — Asparagus lettuce, var. angustana. {After Corhetl.) of the seed stalk after sowing seed, varied from 59 (in Emperor Forcing) to 112 (in Italian Ice) days. The leaves are alternate, denticulate or pinnatifid, sessile or auriculate- clasping, sometimes spinulose-margined, the lowest ones large, and the upper much smaller. The injlorescence is a panicle. The flowers are yellowish or yellowish- white, the involucre cylindric, the bracts of which are imbricated in several series, the outer shorter. The receptacle is flat and n«. i.cd. The corolla rays are truncate and five-toothed at 630 BOTANY OF CROP PLANTS the end. The anthers are sagittate at the base. The style branches are slender. The achenes are oval, oblong, or linear, flat, three to five-ribbed on each face, narrowed above or contracted into a narrow beak which bears a large number Fig. 256. — Cutting or cut-leafed lettuce, var. intybacea. (After Corbell.) of soft, capillary, white or brown pappus bristles. The achenes vary in color: whitish, blackish, yellowish, or brownish. Origin, and Geographical. — It is quite generally conceded by botanists that our garden lettuce {L. sativa) is originated from the wild species, L. scariola. This latter species grows COMPOSITE 631 wild in Europe, Canary Isles, Madeira, Algeria, Abyssinia, and Eastern Asia, and has also become naturalized in the Fig. 257. — Cos lettuce, var. romana. (After Corbetl.) United States, where it is often a troublesome weed. In this country, L. scariola is distributed from New York to Fig. 258. — Head lettuce, var. capitata. {After Corbett.) Minnesota and Missouri. The close relationship between L. sativa and L. scariola is shown by the fact that they readily cross. 632 BOTANY OF CROP PLANTS There are a number of native species of Lactuca in this country. Britton and Brown mention eight species native of the eastern and northern United States, besides the intro- duced L. scariola. This latter species is commonly known as the "compass plant." Fig. 259. — Salsify (Tragopogon porrifolius). From left to right: unopen flower head; side view and face view of open flower head; achene with pappus at tip of beak. Tjrpes of Lettuce. — Four types or botanical varieties of cultivated lettuce are recognized. These may be dis- tinguished by the following artificial key: Key to Types of Lettuce Basal leaves narrow, distinctly lanceolate, L. saliva var. anguslana (asparagus lettuce). COMPOSITE 633 Basal leaves broad, spatulate, oval to roundish, always rounded at the tip. Leaves deeply cut on the edges, L. saliva var. intybacca (cutting or cut- leaved lettuce). Leaves entire or but slightly toothed. Leaves forming a rather compact roundish or flattish head; leaves never decidedly stiff and flat, L. saliva var. capilata (head or cabbage lettuce). Leaves forming a conical or cylindrical-shaped head; leaves straight and stiff, L. saliva \ar. romana (cos lettuce). branches aniher tube corolla pappus ovarxj Fk;. 260. — Single flower of salsify (Tragopogon porrifolius). X 2]^-i. Tracy classifies the American varieties of lettuce as fol- lows: (i) butter varieties, (2) crisp varieties, and (3) cos varieties. These three groups are further subdivided. TRAGOPOGON PORRIFOLIUS (Salsify or "Oyster Plant") Description. — Salsify is a hardy perennial plant from a fleshy root. The roots are about 12 inches long with a diameter of about 2 inches at the top; the skin is grayish white. The stems are usually somewhat branched and succu- lent. When grown from seed, a seed stalk is sent up the second season to a height of 2 to 4 feet. The leaves are alter- nate, entire, linear-lanceolate, clasping at the base, and glau- cous. Heads (Fig. 259) are single at the end of rather long, thickened peduncles, which are often hollow for several 634 BOTANY OF CROP PLANTS inches below the head. The heads are purple and open early in the morning but usually close by noon. The in- volucre is cylindrical, the bracts nearly equal, in one series, linear-lanceolate, and usually much longer than the rays of the flowers. The corollas (Fig. 260) are truncate and five- FiG. 261. — Salsify (Tragopogon porrifolius). Headin fruit; receptacle after having shed the achenes; single achene. toothed at the apex. The anthers are sagittate at the base. The style branches are slender. Achenes are linear, and termi- nated by slender beaks, the outer ones being covered with tubercles, particularly on the ribs below. The pappus is grown together at the base, is plumose, and has interwebbed branches (Fig. 261). COMPOSITE 635 Geographical, and Closely Related Species. — The species is a native of southern Europe. It is quite widely distributed in this country in fields and waste places, probably as an escape from cultivation. A yellow-flowered salsify {T. pratensis), naturalized from Europe, is also quite widely distributed here. The Spanish salsify or Spanish oyster plant (Scolymus hispanicus), has a root much like that of common salsify, but the plant differs from common salsify in the following respects: the roots are of a lighter color and longer, the leaves prickly, and the flowers yellowish. The black salsify {Scorzonera hispanica), also a member of the Composite family, bears a black, fleshy, edible tap root. It differs from common salsify in that its leaves are broader, flowers yellow, and its involucral bracts are in many series. Uses. — Salsify is grown for its fleshy roots which have somewhat the flavor of oysters, hence the common name, "oyster plant." They are used both as a cooked vegetable and as a relish. CICHORIUM (Chicory or Succory, and Endive) Description. — All the species of this genus are branching herbs. The leaves are alternate, mostly basal, the cauline ones small and bract-like. The heads are large, and peduncled or in sessile clusters along the branches. The bracts of the involucre are in two series, the outer spreading, the inner erect. The receptacle is flat, naked, or fringed with small hairs. The corolla rays are truncate and five-toothed at the apex. The achenes are five-angled or five-ribbed, truncate, and not beaked. The pappus consists of a number of short scales. Geographical. — The species of Cichoritim are natives of the Old World. There are two of economic importance: Cichorium intyhus (chicory) and Cichormm endiva (endive). 636 BOTANY OF CROP PLANTS CICHORIUM INTYBUS (Chicory or Succory) Description (Fig. 262). — This is a perennial species from a long, deep tap root, which sends up a stiff, rough-hairy, branched stem to a height of i to 3 feet. Radical leaves are numerous, and spreading on the ground; the upper leaves are smaller, lanceolate or oblong, lobed or entire, clasping and auricled at the base. The heads are axillary. The flowers are blue or purplish, and sometimes white. The species is a native of Europe. It is introduced into the United States, occurring as a ruderal from Nova Scotia to North Carolina, and west to Minnesota and Missouri. Uses, and Varieties.^ — The roasted root of chicory has been used as a substitute for, and an adulterant of, coffee. The young roots are sometimes boiled, and the leaves used as "greens" or served fresh as a salad. The plant is some- times forced in the winter to produce a cluster of loose leaves for use in salads. Such clusters of leaves are called "Barbe de Capuchin." Common varieties of chicory are: Common, Large-rooted Madgebury, Long-rooted Brunswick and Improved very Large-leaved. Witloof chicory is an improved variety of Belgian origin. CICHORIUM ENDIVA (Endive) Description. — Endive is an annual or biennial herb with numerous basal leaves which vary much in character; they may be merely toothed, the teeth large or small and numerous, or pinnatifid; some of the most desirable varieties have the leaf margins very much curled. The upper leaves are smaller, and auricled at the base. The stem often rises to a height of 3 feet; it is hollow, terete, branched, and smooth or slightly hirsute. The flowers are purple and sometimes white. The achencs are angular and ribbed. COMPOSITE 637 Fig. 262. — Chicory (Chicorium intybus). A, sessile clusters of flowers in axils of bracts, Xi; B, single floral bract enlarged, X 4; C, open flower, face view, enlarged; D, basal leaf, X i>2. 638 BOTANY OF CROP PLANTS Geographical Distribution, and Economic Uses.— Endive is a native of India. It is cultivated to a great extent in the gardens of European countries and to some extent in Fig. 263. — Tubers of Jerusalem artichoke (Helianthus tuberosum). (After Vilmorin.) the United States. The best-known variety grown here is the Green Curled. The plant is cultivated for the young basal leaves which are blanched and used as a salad. COMPOSITE 639 HELIANTHUS TUBEROSUS (Jerusalem Artichoke) Description. — The Jerusalem artichoke is a perennial herb arising from thick, fleshy rootstocks that bear oblong tubers (Fig. 263). The above-ground stems attain a height of 6 to 12 feet; they are stout, branching, terete and hirsute. The leaves are alternate above, opposite below, simple, ovate or ovate- oblong, firm, three-nerved at the base, narrowed, rounded, truncate or slightly heart-shaped at the base, acuminate at the apex, and long petioled. The heads are. solitary or in corymbs. Tubular (disk) and ligulate (ray) flowers are both present; the rays are yellow and the disk is also yellow (Fig. 254). The involucre is hemispheric, with lanceolate, acumi- nate hirsute or cihate, squarrose bracts. There are 12 to 20 rays. The receptacle is chaffy; the chaff subtends the disk flowers. The achcnes are thick, somewhat four-angled, and pubescent. The pappus consists of two deciduous scales. Geographical. — The Jerusalem artichoke (also called Earth Apple, Canada Potato, Girasole and Topinambourj is native to this countrj' and is found from New Brunswick and Ontario to Georgia and Arkansas, west and north to Canada. It is grown as a crop more in Europe than in America. Closely Related Species. — The Jerusalem artichoke is closely related to the ''globe artichoke" {Cynara scolymus) which in fact belongs to the same family, Compositae. Cynara scolymus is sometimes cultivated for the flower heads and leaves. The thick receptacle together with the fleshy bases of the scales of the involucre is used as a vegetable. The plant may be distinguished further from Jerusalem artichoke by its blue or violet-purple flowers, and its large, wooly, pinnatifid leaves. Uses.^ — The tubers of Jerusalem artichoke are used both as a vegetable and as a food for stock. Hogs are turned into the field and permitted to root the tubers from the ground. References Tracy, W. W.: American Varieties of Lettuce. U. S. Dept. .\gr. Bur. Plant Ind. Bull. 69: 1-103, 1905. GLOSSARY Abaxile. — Situated off the axis. Abortive. — Imperfectly formed or rudimentary. Acaulescent. — Without an obvious stem. Accumhent (cotyledons). — Their edges against the hypocotyl. Achenc (akene). — A one-celled, dry, indehiscent fruit in which the testa and pericarp are not firmly attached. Aero petal. — Developing from the outside (below) toward the inside (above). Actinontorphic. — Regular, ray-shaped; said of a flower when it can be divided into symmetrical halves by radial planes. A cuminaie. — Taper-pointed. Acute. — Merely sharp-pointed, or ending in a point less than a right angle. Adnate. — Grown fast to; applied to the growing together of unlike parts. Adventitious. — Out of the ordinary place, as applied to buds or roots. Aestivaticn. — The arrangement of parts in the bud. Alliaceous. — With odor and taste of onions and garlic. Alternate (buds, flower parts, leaves, etc.). One after another singly at the nodes. Anient. — Scaly unisexual spike of flowers. Amphilrcpous (ovules). Half-inverted and straight, with the hilum about the middle, and mieropyle terminal. Anatropous (ovules). — Inverted, straight and with mieropyle next the hilum. Androecium.—^he stamens collectively. Annual (plant). — Produces flowers, fruit, and seed the same year it is raised from seed, and then dies. Winter annuals germinate in autumn, and produce seed the following spring or summer. Annular. — Forming a ring or circle, as embryo of beet. Apetalous. — Without petals, as in buckwheat, etc. Apical. — At the tip or apex. Apocarpy. — Condition in which the carpels are separate. Apopetaly. — Condition in which petals are separate and distinct. Articulated. — Jointed. Auricle. — Ear-like structure. Auriculate. — Eared; furnished with ear-like appendages. Autogamy. — Pollination in which pollen is transferred from the anthers to the stigma of the same flower. Awn. — Bristle-like structure, or beard. 41 641 642 BOTANY OF CROP PLANTS Aivned. — Furnished with an awn or beard. Axillary (buds, etc.). — In the a.xil. Basal. — Belonging to or attached to the base. Berry. — A fleshy fruit, with mesocarp and endocarp fleshy throughout, and seeds imbedded therein, as grape, currant, etc. Biennial. — Of two years' duration; the first year from seed, the second year flowering and fruiting, then dying; as in sugar beet, carrot, etc. Bipinnale (leaf). — Twice pinnate. Blade. — Expanded portion of a leaf. Bloom. — The whitish, powdery, and waxy secretion of epidermal cells. Bract. — A reduced scale-like leaf, above the regular foliage leaves. Bracteclaie. — Bearing bractlets. Bracteclc. — A small bract. Bulbils. — Small bulbs borne underground, as in garlic. Bulhlets. — Small bulbs borne above ground, as in tree onions. Cambium. — The growing layer in the vascular bundle. Campanulate. — Bell-shaped. Catnpylolropous (ovule or seed). — Curved so as to bring the apex and base near together. Capillary. — Hair-like in form. Capitate. — Knob-like; shaped like a head. Caprification. — The artificial process of pollinating figs. Capsule (pod). — A dry, dehiscent fruit of two or more carpels. Carina. — Keel. Carpophore. — A slender stalk to which the mericarps of the umbelliferous fruit are attached. Caryopsis. — Synonym of grain — a drj^, indehiscent one-seeded fruit in which the pericarp and testa closely adhere. Catkin.- — Ament. Scaly spike of flowers. Caudate. — Tailed; with a slender tail-like appendage. Cauliflorus. — Stem- flowering; trunks bearing flowers, as in figs. Cauline.—PeitSiinmg or belonging to the stem. Chasmogamy. — Flowers that regularly open are said to show chasmogamy. Ciliate. — Fringed with marginal hairs. Cladophyll. — A leaf-like branch. Claw. — The narrow or stalk-like base of some petals. Cleft. — Cut about halfway to midrib or median line. Ccleoptile. — Leaf sheath in grasses. Colecrhiza. — A sheath about the root. Commissure. — The contiguous surfaces of two carpels, as in the fruit of Umbelliferae. GLOSSARY 643 Coudu plicate. — Folded lengthwise. Connivcni. — Ovcrla|)ping or brought close together. Couvcrgcul. — iMargins touching. Convolnlc. — Rolled lengthwise. Cordiilc. — Heart-shaped. Corncus. — Horny. Conn. — The swollen, flesh)-, and solid base of a stem. Corte.v. — Bark region, from epidermis to endodermis. Corymb. — An indeterminate tj^pe of inflorescence that is flat-topped. Corymbose. — Corymb-like. Crenale. — Margins with rounded teeth. Crcnulate. — With very small rounded teeth; diminutive of crenate. C«/w.— The hollow stem of grasses and sedges. Cuticle. — A thin covering of a waxy substance called cutin on the outer wall of epidermal cells. Cyme. — A determinate type of inflorescence, in which the first flowers to open are those toward the inside. Cymose. — Cyme-like, or bearing cymes. Decompound. — Several times compound or divided, as in leaves of carrot. Decumbent. — More or less prostrate, but with the tips ascending. Decurrent (leaf). — Extending down the stem below the point of insertion. Dehiscence. — The opening of a fruit or anther. Dehiscent. — Splitting open. Dentate. — Sharp-toothed; teeth directed forward. Denticulate. — Diminutive of dentate; furnished with very small sharp teeth. Diadelphous (stamens). — United into two sets, as in many legumes. Diaphragm. — .\ dividing partition. Dichogamy. — A condition in which stamens and pistils do not mature simultaneously. Didinism. — Stamens and pistils in separate flowers, as in dioecious and monoecious plants. Digitate. — The spreading of segments like the fingers from palm of hand. Dilated. — Expanded. Dimorphism. — The occurrence of two distinct forms, as in flowers of buck- wheat. Diacious. — Bearing staminate and pistillate flowers on different individual plants. Dissected. — Divided into many lobes or segments. Distichous. — Two-ranked, as the leaves of grasses. Divergent. — Spreading apart. Divided. — Segmented to the midline, midvein, or base. Dorsal. — On the back; surface of member turned awav from the main axis. 644 BOTANY OF CROP PLANTS Drupe. — A one-seeded, fleshy fruit in which the endocarp is stony, the mesocarp fleshy, and exocarp skin-like. Drupelet. — A small drupe, as in raspberry. Ellipiic. — Oval, or the shape of an ellipse. Emarginate. — Notched at the apex. Embryo. — Young plant within the seed. Endocarp. — Inner wall of pericarp (ovary wall). Endosperm. — The stored food supply in a seed. Entire. — Without divisions, lobes, or teeth; usually refers to margins of leaves, petals, and sepals. Epicalyx. — Extra bract-like segments below the calyx in the strawberry. Epigynous. — Ovary inferior; flower parts above the ovary or apparently growing from its tip. Epiphyllous. — Borne on leaf surface. Epiphyte. — Growing upon another plant, but gaining from it no nutriment. Episperm. — Testa; seed coats. Erase. — With an irregular margin, as if chewed. Etiolate. — To whiten, or blanch, by the exclusion of light. Exocarp. — Outer wall of pericarp (ovary wall). E.xserted (stamens). — Extending beyond the other flower parts. E.xstipulate. — Without stipules. Extravaginal. — Referring to branches in grasses which force their way out through the base of the leaf sheath. Extrorse. — Turned outwards; usually referring to anthers which shed their pollen towards the outside of the flower. Falcate. — Shaped like a scythe. Fascicle. — Bundle or cluster. Fertile. — Capable of bearing fruit or seed; applied to flowers with pistils or to anther with pollen. Fertilization. — A sexual process in which two dissimilar gametes fuse. Fibrous. — Fiber-like, usually referring to root system of many small thread- like roots. Filament.- — Thread; stalk of stamen. Filamentous. — Thread-like. Fimbriated. — Fringed. Foliaceous. — Leaf-like in form and texture. Follicle. — A dry, dehiscent fruit with one carpel which splits along the ventral suture. Funnel form. — Funnel-shaped. Gcilonogamy. — A method of pollination in which pollen is taken from anther to stigma of another flower on same plant. GLOSSARY 645 Gcniculalc.—Bcni aliruptly at an angle, like the bent knee. Glabrous. — Smooth; without hairs, scales, or bristles. Glandular. — Furnished with glands. Glaucous.— Covered with a fine, waxy-like covering (bloom) which rubs off easily. Globose. — Globe-shaped. Globular. — Globe-shaped. Glume. — General name for floral bract of grasses and sedges. Gynarium. — The carpels taken collectively. Hastate. — Halberd-shaped; basal lobes diverging. Head.—An indeterminate type of inflorescence in which the flowers are m a dense cluster, as in Compositae. Hermaphrodite (flowers).— Perfect; both stamens and pistils present. Hyaline. — Thin and very nearly transparent. Hypocotyl.— That portion of the embryo stem below the cotyledons. Hypogean (cotyledons). — Remaining underground, as in the pea. Hypogynous. — Ovary superior; flower parts attached below the ovary. Hilum.— The scar on a seed, marking the attachment of a seed to its stalk. Hirsute. — Covered with stiff hairs. Homogamy. — The anthers and stigmas mature at the same time. Imbricated. — Overlapping. Incised. — Cut rather deeply into sharp lobes. Included (stamens). — Not extending beyond the surrounding parts. Incumbent (cotyledons).— With the backs against the hypocotyl. Indckiscent. — Not splitting open. Indigenous. — Native to the region of growth. Inferior (ovary). — Below the other flower parts. Injle.xed. — Bent inwards. Inflorescence.^A flower cluster. Integument. — Skin; coat or protecting layer. Inlernode. — The interval between two adjacent nodes. Intravaginal. — Referring to branches in grasses which grow out between the leaf sheath and the culm (stem). Introrse. — Turned inwards; usually referring to anthers which shed their pollen towards the inside of the flower. Involucel. — A secondary involucre. Involucellate. — Furnished with involucels. Involucrale. — Furnished with an involucre. Involucre. — A series of bracts that subtend an inflorescence, as in Compos- itae, cotton, etc. Irregular (flower). — One or more of the parts of a series are dissimilar. 646 BOTANY OF CROP PLANTS Keel. — Ridge, like the keel of a boat. Laciniak. — Cut into narrow, rather deep segments. Lamella. — Plate. Lanceolate. — Lance-shaped. Lemma. — The bract (glume) at the base of the flower in grasses. Lenticular. — Shaped like a double-convex lens. . Lignified. — Woody; cell walls impregnated with lignin. Ligulate. — Strap-shaped. Ligulc. — Appendage at juncture of sheath and blade in grasses, or, strap- shaped corolla in Compositae. Linear. — ^Long and narrow, its sides nearly parallel. Lobed. — Divided to about the middle. Lociile. — Cell cavity. Loculicidal. — Refers to capsules which split lengthwise through the middle of each cell. Lodicules. — Small scales (inner perianth) surrounding the ovary in grasses. Lumen. — Cell cavity. Lyrate. — Lyre-shaped; the end lobe of pinnatifid leaf is much larger than the rest. Marginal. — Along the edge or margin. Median. — Middle. Medulla. — Pith. Mericarp. — One-half of the fruit of Umbelliferae. Mesocarp. — Middle layer of pericarp (ovary wall). Mesocotyl. — Axis between base of coleoptile and grain, in grasses. Micropyle. — The opening between the ovule or seed coats. Micros porangium. — Anther sac; case bearing microspores'. Monoecious. — Staminate and pistillate flowers in different inflorescences on same plant. Mucronate. — With a sharp and abrupt point. Nerve. — Veins or ribs in bracts, scales, petals, sepals, etc. Node. — The point on the stem from which a leaf or leaves arise; the junction of two internodes. Nucelliis (megas porangium). — The ovule tissue within the integuments. Nutlet. — A small nut. Ob. — A prefix signifying inversion. Obcordate. — Heart-shaped, with broad end at the tip. GLOSSARY 647 Oblaic. — -Flattened at the ends. Obovale. — Egg-shaped in outHne, with the broader end at the tip. Obsolete. — Rudimentary, or entirely absent. Obtuse. — Blunt or rounded at the apex. Ocrcce. — Sheathing stipules in Polygonaceae. Orbicular. — .Approximately circular in outline. OrtJiolropGus (ovule). — Straight; hilum at one end and micropyle at the other. Ovate. — Egg-shaped in outline; broader end at the base. Ovoid. — Egg-shaped. Ovule. — The bod\' which becomes the seed after fertilization. Palet (palea). — Outer perianth segment of grass flower. Palmate. — Leaf segments or leaflets radiate from a point like the fingers from the palm of the hand. Panicle. — A compound raceme, as in oats. Paniculate. — Flowers in panicle or panicle-like inflorescence. Papilla. — A small protuberance. Papillose. — With papillae. Pappus. — Bristle-Hke, awn-like scaly structures (modified calyx) at the tip of the ovary in Composite. Parenchyma. — A tissue made up of large, thin-walled cells with rather large intercellular spaces. Parietal. — Pertaining to the wall; ovules that are attached to the wall of the ovary are said to be parietal. Parted. — Separated into parts nearly to the base. Parthenocarpy. — A phenomenon in which the fruit matures without fertili- zation of ovules. Pedicellate. — Possessing a pedicel. Peduncle. — A stalk, either of an individual flower or of the inflorescence. Pendant. — Hanging. Pentamerous (flower). — 'Parts in fives. Perfect (flower). — Possessing both stamens and pistils; hermaphroditic. Perennial. — Living from year to 3'ear. Perianth. — Calyx and corolla taken collectively, or the external floral whorl or whorls. Pericarp. — The ovary wall, consisting of three layers: exocarp, mesocarp, and endocarp. Pcrigynous. — Calyx, corolla, and stamens borne on a rim of the receptacle such that they appear on the level with the ovary. Perisperm. — Nucellus. Pctaloid. — Petal-like . Petiole.— The stalk of a leaf. 648 BOTANY OF CROP PLANTS Phlcem. — That portion of a vascular bundle which is largely concerned in the transport of elaborated food material. Phyllolaxy. — The arrangement of leaves upon a stem. Pileole. — Coleoptile (which see). Pinnate (leaf). — Leaflets arranged along the sides of an axis. Pinnalifid. — Pinnately cleft to the middle of the blade, or further. Pistillate. — Bearing pistils only. Placenta. — The membrane or surface bearing ovules. Plicate. — Plaited. Plumose. — Plume- or feather-like. Plumule. — The first bud in the young plant. Polyadelphous (stamens).— Separate, or in more than two groups. PclygamO'di(Pcioiis. — Bearing both perfect and imperfect flowers on the same plant, with a tendency to become dioecious. Polygamous. — Both perfect and imperfect flowers present on the same plant. Pome. — A fruit in which the receptacle of the flower enlarges, becomes fleshy and surrounds the carpels, as in apple, pear, and quince. Prehensile. — Adapted for holding. Protandry. — In which the anthers of a flower shed their pollen before the stigmas are receptive. Protogyny. — In which the stigmas of a flower are receptive before its anthers shed their pollen. Pubescence. — Fine, soft hairs. Pubescent. — Covered with fine, soft hairs. /?ace;we.— Indeterminate type of inflorescence, in which the pedicels are simple and one-flowered. Racemose. — Raceme-like. Rachilla. — The axis of a spikelet. Rachis. — The axis of a spike. Radical.— -Seeming to come from the root. Leaves arising from the base of stem, close to the ground line, are said to be radical, as contrasted with those on the stem {cauline). Ray. — The branch of an umbel; marginal, ligulate flowers of a composite head. Receptacle. — The end of the axis to which the floral organs are attached; torus. Refiexed. — Turned back. Regular (flower). — The parts of each whorl similar. Reniform. — Kidney-shaped. Reticulate. — Netted. Retrorse. — Turned back or downward. GLOSSARY 649 Rhizome. — Rootstock; underground stem, usually horizontally elongated. Rotate. — Wheel-shaped . Ruderal. — Growing in waste places; weed. Runner. — A prostrate, slender, above-ground stem, such as in the straw- berry. Saccate. — With a sac. Sagittate. — Shaped like an arrow-head, with the lobes turned downward. Salverform (sympetalous corolla). — Tubular with a spreading limb. Scabrous. — Rough. Scale. — Reduced leaf that appears lower on the stem than the foliage leaves. Scapose. — Bearing a nearly leafless flower stalk arising from the base of the plant. Schizocarp. — A dry, indehiscent fruit, of two carpels, each one-seeded, which split apart at maturity into two halves or mericarps. Sclcrenchymatous. — Composed of cells that fit closely together and have thick, hardened walls. Scutcllum. — Morphologically, the cotyledon of the grass embryo. Segment. — A division of a leaf, fruit or flower. Seminal. — Belonging to the seed. Septum. — Partition or dividing wall. Serrate. — With sharp teeth that point forward. Sessile. — Sitting; without a stalk. Sheath. — A tubular envelope about the stem, such as occurs in the leaves of grasses. Silicle. — Similar to a silique, except that it is broader than long. Siliqne. — Pod-like fruit of mustards, dehiscent, two-valved, and with two parietal placentas; longer than broad. Sinuate. — Wavy along the margin. Sinus. — The space between two lobes. Spathe. — A large bract or pair of bracts, subtending a spadix or flower cluster. Spatulate. — Shape of a spatula or spoon. Spicate. — Spike-like. Spike. — An indeterminate type of inflorescence in which numerous sessile flowers are borne on a rachis. Spikelet. — The unit of inflorescence in grasses and sedges; a small spike. Spinulose. — With small spines. Squarrose. — With spreading parts. Staminal. — Of or pertaining to stamens. Slaminatc (flowers). — Bearing stamens only. Stamiuodcal. — Pertaining to staminodia, i.e., abortive and sterile stamens. 650 BOTANY OF CROP PLANTS Standard. — The large petal in the flowers of Leguminosae. Sterile. — Unproductive; without the reproductive elements. Stipitate. — Provided with a stalk or stipe. Stipules. — Appendages at the base of the petiole. Stipulate. — Bearing stipules. Stolon. — A trailing stem, above ground, that easily takes root at the nodes when it touches the ground. Stooling. — Production of secondary branches from lowermost nodes, as in grasses; tillering. Strobile. — Spike-like pistillate inflorescence of hop; also cone-like group of sporophylls. Stylar. — Of or pertaining to style. Stylopodium. — Style-foot. The nectariferous gland at the base of the style in the Umbelliferous fruit. Sub. — Prefix signifying below, under, or almost, less than normal, in an inferior degree. Subtend. — To grow under, or be adjacent to, as a bract subtending a flower. Subulate. — Awl-shaped. Sucker. — Rapidly growing shoots from roots or from stems underground. Superior (flower). — Ovary appearing above the other parts of the flower. Sympetaly. — Petals united. Suture. — A line of splitting. Sympetalous. — With the petals united to form a tube. Syncarpy. — Condition in which the carpels are united. Synconium. — Fleshy fruit, in which the receptacle is hollow, and its inner wall is lined with numerous flowers. Syngenesious. — With the anthers united, as in Compositae. Tassel. — Stamina te inflorescence in corn. Tendril. — Slender, coiled organ used in climbing. Terete. — Cylindrical; pencil-shaped. Ternate. — Arranged in threes or divided into three divisions. Testa. — Seed coat. Tillering. — Production of branches from the lowermost nodes, as in grasses. Tomcntose. — Covered with dense wool-like hair. Tomcntum. — Dense, woolly hair. Torus. — Receptacle of a flower. Translucent. — Partially transparent. Trifoliate. — With three leaflets, as in clover. Truncate. — As if cut off squarely at the tip. Tuberculate.- — ^Furnished with tubercles or small projections. Tuberous. — Swollen and tuber-like. Tubular. — Tube-shaped. Turbinate. — Top-shaped. GLOSSARY 651 Umbel. — An indeterminate type of inflorescence, in which the pedicels arise from the same point. Umbellate. — Umbel-like. Umbellet. — Umbel of secondary order. Undulak. — With wavy margin. Utricle. — A one-seeded fruit with a bladder-like covering. Valvale (arrangement of parts in the bud). — The segments meet with their edges, without any overlapping. Valves. — One of the pieces into which a capsule splits. • Venation. — The arrangement of veins. Ventral. — On the lower side; surface of member turned toward the main axis. Vernation. — .\rrangement of leaves in the bud. Versatile (anther). — Filament is attached near middle of anther, so that it can readily turn in any direction. Vexillum. — Standard of the flower in Leguminosa;. Viscid. — Sticky. Vilta (pi. vittas). — Oil tubes in Umbellifer fruit. Wing. — Lateral petal in the flower of Leguminosaj. Whorl.— X group of organs arranged in a circle about a stem, and arising from the same node. Zygomorphy (flower). — See Irregular. INDEX Abutilon, 506 Abyssinian oats, 130 Achene, ScS Achillea, 625 Acrospire, 144 Adjuki bean, 423 Adriatic figs, 275 Aegilops, no African cotton, 517 millet, 213 Agave, 47, 281 Agropyron repens, 70, 75 Agrostis, 81 Aino millet, 218, 219 Alae, 415 Albumin, 105 Aleurone layer, 102 Alfalfa, 442 American, 447 Arabian, 447 Baltic, 447 German, 447 Grimm, 447 Peruvian, 447 sickle, 447 Turkestan, 447 variegated, 447 yellow-flowered, 447 Algie, 62, 63 Algerian oat, 131 Allium, 231 ascalonicum, 231, 237, 238 cepa, 232, 237, 240 bulbellifera, 241 multiplicans, 241 fistulosum, 232, 237, 239 sativum, 236, 237 schoenoprasum, 231, 232, 237, Almond, 410 bitter, 411 hard -shelled, 411 oil, 411 soft-shelled, 411 sweet, 411 Aloe, 229 Alopecurus, 79 Alsike clover, 433, 434 Althaea, 506 ofHcinalis, 507 rosea, 507 Amarelles, 404 Amaryllidaceas, 281 Amelanchier, 366, 367 American alfalfa, 447 cotton, 512, 520 cranberry, 548 black currant, 319, 320 crabapple, 379 flowering currant, 319, 320 gooseberries, 321 ivy, 492 laurel, 543 plum, 397, 400, 401 red raspberry, 357 upland cotton, 520 Amygdalus persica, 407 Amyris, 475 Andropogon, 87, 88 sorghum, 191 halepensis, 197 Angelica, 532 Angiospermaj, 62 Animated oats, 131 Annual ring, 40 Annuals, 21, 70 >38 Anlcnnaria, 625 653 6S4 INDEX Anther, 48, 49 Anthyllis, 429 Antipodals, 50 Apium, 533, 538 graveolens, 539, 540 rapaceum, 540 key to principal species of, 539 leptophyllum, 539 petroselinum, 539 Apple, 367 American crab, 379 common, 379, 381 family, 366 flowering crab, 379 narrow-leaved crab, 379 Siberian crab, 379 Soulard crab, 379, 381 western crab, 379, 381 Apricot, 405 black, 407 common, 405 Japanese, 407 purple, 407 Siberian, 407 Arabian alfalfa, 447 Arachis, hypogcea, 462 Aragallus, 414 Arctostaphylos uva-ursi, 543 Arnica, 625, 628 alpina, 600 Arrhenatherum elatius, 75 Artemisia, 625, 628 Artichoke, globe, 639 Jerusalem, 639 Artificial gums, 185 Artocarpus communis, 252 Arundinaria, 84 Ascomycetes, 64 Asiatic cotton, 511, 512 Asparagus, 244 bean, 422, 458 falcatus, 244 "fern" 246 Asparagus, laricinus, 244 lettuce, 632 medcoloides, 246 officinalis, 244, 246 plumosus, 246 sprengeri, 246 Aster, 625, 628 Astragalus, 414 Atriplex, 296 hortensis, 299 Atropa belladonna, 559 Auricle, 78 Australian tobacco, 600 Autogamy, 51, 94 Autumn wood, 40 Avena, 88, 123 abyssinica, 130 algeriensis, 131 barbata, 131 brevis, 130 byzantina, 130, 131 fatua, 128, 130, 131 nuda, 130, 131 orientalis, 125, 130, 131 sativa, 89, 125, 126, 128, 130, 131 sterilis, 131 strigosa, 130, 131 wiestii, 131 Awns, 82 Azalea, 543 Bagasse, 227 Baltic alfalfa, 447 Bamboo, 69 Bambusse, 84 Banner, 414 oats, 130 Banyan, 16 tree, 267 Barbe de Capuchin, 636 Bark, 39, 40 Barley, 72, 88, 89, 135 black, 145 INDEX 655 Barley, blue. 145 fail, 146 four-ruwcd, 144 hooded, 136, 137, 145, 146 hull-less Jerusalem, 145 hybrid, 145 medium, 137, 143, 145, 146 Nepal, 145 peacock, 146 six-rowed, 144 two-rowed, 145 bent, 147 erect-eared, 147 naked, 146 nodding, 147 Barnyard grass, 219 millet, 210, 210, 220 Basidiomycetes, 64 Basin, 378 Bean, 421 adjuki, 423 asparagus, 422, 458 broad, 422, 426, 429 coffee, 456 Dolichos, 422 Dutch case-knife, 423 flowering, 423 hyacinth, 422 Jack, 422 kidney, 423, 426 Lima, 423, 424 locust, 422 Mexican, 424 mung, 423 painted lady, 423 scarlet runner, 423 Sieva, 423, 424 soja, 456 soy, 422, 455 velvet, 422 Windsor, 427, 429 Beards, 82 Beet, common garden, 300, 310 Beet, foliage, 301 leaf, 301, 312 * ornamental, 301 pulp, 309 sea-kale, 312 seed, 306 multiple-germ, 306 single-germ, 306 silver, 312 spinach, 312 sugar, 300, 301 wild, 301 Belladonna, 559 Benincasa cerifcra, 613 Bergamot, 487 Beriberi, 206 Berry, 59 Berseem, 433 Beta, 298 cycla, 312 maritima, 301 vulgaris, 300 Bidens, 625 Biennials, 21 Bigarreaus, 403 Bilberry, dwarf, 546 tall bilberry, 547 thin-leaved, 544 Bindweed, 284 Binomial system, 64 Bird's-foot trefoil, 466 Bistort, 286 Bittersweet, 561 Black apricot, 405 barley, 145 bitter vetch, 428 blueberr>', 547 -cap raspberry, 357 mulberry, 255, 257 mustard, 327, 339 nightshade, 560 salsify, 635 Blackberrj', 354 6;6 INDEX Blackberry, dewberry, 354 high-bush, 354 * key to principal species of, 354 leafj'-cluster, 354 long-cluster, 354 loose-cluster, 354 sand, 354 white, 354 Blade, 42, 77 Blanched asparagus, 250 Blastophaga, grossorum, 271 Blitum capitatum, 296 Blood orange, 484 Blue barley, 145 Blueberry, 550 black, 547 Canada, 546 high bush, 547, 550 low, 546 black, 546 bush, 550 Bokhara, 453 Boll, 514 Bonavist, 422 Brace roots, 16, 159 Bracteole, 80 Bracts, 78 Brambles, 351 Bran, 106 layer, 105 Brandy, 503 Brassica, 326, 327 alba, 327, 340 arvensis, 339 campestris, 328, 337 juncea, 340 key to species of, 327 napus, 328, 338 nigra, 327, 339 oleracea, 328 botrytis, 330, 334 capitata, 329, 331 caulo-rapa, 330, 33s Brassica, oleracea, gemmifera, 329, 330 viridis, 329, 330 rapa, 65, 328, 335 Bread-fruit, 252 Breaking, hemp, 280 Brebas, 275 Brewing process, 149 British gums, 185 Broad bean, 422, 426, 429 Broccoli, 334 Bromus inermis, 76 Broom corn, 88, 196, 197 -corn millet, 210, 213 Brown mustard, 339 Brush, 99 Brussel's sprouts, 329, 330 Bryophytes, 62 Buchloe, 70 dactyloides, 76 Buckbean, 414 Buckwheat, 286, 289 common, 289 gray, 294 family, 284 Japanese, 294 notch-seeded, 294 silver hull, 294 Tatary, 293 Bud variation, 25 Buds, 23 accessory, 24 adventitious, 24 alternate, 25 axillary, 24 branch, 23 classification of, 23 dormant, 23 flower, 23 grafting, 23 lateral, 24 leaf, -23 mixed, 23 opposite, 25 INDEX 657 ]^U(ls, (crminal, 24 supernumerary, C4 whorled, 25 Buffalo bur, 561 currant, 319 Bulbs, 32, 229 BuUaces, 400 Bulletin Smj-rnas, 275 Bundle scar, 26 Buplcurum, 530 Cabbage, 328 common, 331 key to cultivated types of, 329 types of common head, 332 lettuce, 633 Calamondin orange, 487 Calendula, 625 J Callirrhoe, 508 Calyx, 48 Cambium, 36 ring, 38 Camelina, 326 Campanulaceae, 600 Canada blueberry, 66, 546 crookneck squash, 615 potato, 639 rice, 206 thistle, 21, 28 Canadian field pea, 420 Cane sugar, production of, 228 Cannabis, 252 indica, 281 sativa, 276 Cantaloupe, 618 Caper family, 326 Capparidacea?, 326 Caprification, 273 Caprifig, 269, 272, 276 Capsaican, 595 Capsella, 326 Capsicum, 560, 595 annuum, 592 Capsicum, annuum, al)l)rLviatuni, 595 acuminatum, 595 ccrasiforme, 595 conoides, 595 fasciculatum, 595 frutesccns, 595 grossum, 595 longum, 595 Capsule, 58 Caraway, 533 Carbohydrate synthesis, 46 Carduus, 625, 628 Carina, 415 Carolina rice, 206 Carpophore, 532 Carrot, 533 family, 530 Carum, 533 Caryopsis, 83 Catawba grape, 501 Catjang, 458 Cat-tail millet, 213 CauHflower, 330, 334 Cavity, 378 Cayenne pepper, 595 Ccleriac, 540 Celery, 540 Cell, 4 as unit of structure, 5 of plant activity, 5 Cell sap, 6 wall, 6, 8 CeUuloid, 526 Central cylinder, 17 Cercocarpus, 348 Cereals, 87 key to groups (genera) of, 87 small-grain seedlings of, 88 Chsetochloa, 88, 210, 211 italica, 211, 216, 218 key to principal types of, 218 maximum, 218 moharium, 219 658 INDEX Chaetochloa, viridis, 211, 219 Chard, 312 Charlock, 339 Chasmogamy, 82 Chenopodiacese, 296 key to principal genera of, 297 Chenopodium, 297 Cherry, 401 sour, 403 sweet, 402 tomato, 587, 590 Chicasaw plum, 401 Chick pea, 467 Chicory, 628, 635, 636 Chilean strawberry, 363, 364 Chilli con carne, 596 Chinese cotton, 517 mustard, 340 pear, 384, 385 Chiogenes hispidula, 543 Chives, 237, 238 Chlorophyceae, 63 Chloroplastids, 8 Chromoplastids, 8 Chrysanthemum, 625, 628 Chrysothamnus, 625 Ciboule, 237, 239 Cicer arietinum, 467 Cichorium, 628 endiva, 635, 636 intybus, 635, 636 Cider, 383 Cinque-foil, 348 Citrange, 489 Citron, 480, 622, 623 Citrullus, 610, 622 vulgaris, 623 Citrus, 476 aurantifolia, 480, 483 aurantium, 480, 487 bergamia, 487 grandis, 480, 485 ichangensis, 487 Citrus, key to principal species of, 479 limonia, 479, 481 medica, 479, 480 mitis, 487 nobilis, 480, 485 deliciosa, 485 unshiu, 4S5 sinensis, 480, 484 Give, 237, 238 Cladophylls, 244 Classification and naming of plants, 60 Cleistogamy, 82 Close pollination, 51 Clover, 66, 432 • Alsike, 433, 434 Berseem, 433 crimson, 433, 435 Dutch, 433 hop, 442, 449 giant, 453 Italian, 435 Japan, 465 Ladino, 434 mammoth, 433, 430, 441 meadow, 441 medium red, 441 Persian, 433 purple, 436 red, 433, 43^ scarlet, 433, 435 Shaftal, 433 spotted bur, 442, 449 Swedish, 433, 434 sweet, 452 toothed bur, 442, 452 white, 433, 441 zigzag, 433, 441 Cloudberry, 350 Club mosses, 62 wheat, III, 112, 114 Cob, 163 Cofifee bean, 456 Coleanthus, 81 INDEX C'>S9 Coleoptilc, 104 Colcorliiza, 10, ro3 Collard, 329, 330 Collodion, 526 Colocynth, 622 Columnar epithelium, 104 Commissure, 532 Common apple, 379, 381 apricot, 405 barnyard grass, 210 bread wheat, in, it2, 113, 114 buckwheat, 289 eggplant, 586 fig, 2,69, 275 gray buckwheat, 294 hop, 33 millet, 219 onion, 232, 237 pear, 384, 3S5 six-rowed barley, 144 sugar beet, 300, 310 sweet pea, 432 wheat, 65, III, 112, 114 Companion cells, 35 Compass plant, 632 Composite family, 625 Composite, 625 key to important genera of, 628 Concord grape, 501 Conium, 532 Convolvulaceae, 554 key to important genera of, 555 Convolvulus, 554 Cordelia figs, 276 Corchorus capsularis, 281 olitorius, 281 Core line, 377 Coriander, 533 Corinth currants, 501 Cork cambium, 38 tissue, 38 Corms, 32 Corn, 157 Corn, dent, 178, 180 flint, 178, 180 fodder, 185 oil, 184 pod, 178, 180 pop, 178, 180 soft, 178, 180 starchy sweet, 178, 180 sweet, 178, 180 starch, 184 stover, 186 xenia in, 172 Corolla, 48 Coronilla, 429 Cortex, 17 Corymb, 56 Cos lettuce, 633 Cotoneaster, 366 Cottolene, 524 Cotton, 508 African, 517 American, 512 Asiatic, 511, 512 Chinese, 517 Egyptian, 510 Guatemalan, 512 Nankin, 517 Red Peruvian, 517 Sea Island, 520 types and varieties of American, 521 Upland, 510, 520 Wild, 520 Cottonseed hulls, 524 meal, 524 oil, 524 Couloure of Muscat grape, 498 Cowberry, 550 Cowpea, 460 Crab-apple, American, 379 flowering, 379 narrow-leaved, 379 Siberian, 379 Soulard, 379, 381 66o INDEX Crab-apple, western, 379, 381 Cranberr^v, 548 American, 548 European, 544 large, 548 mountain, 550 small, 548, ^49 types of, 549 Cratffigus, 366, 367 Creeping snowberry, 543 wintergreen, 543 Crimson clover, 433, 435 Cross pollination, 52 artificial, 95 Crown vetch, 429 Cruciferae, 323 key to principal genera of, 326 Cucumber, 615, 617, 620 common field, 620, 621 English forcing, 621 Jerusalem, 617 musk, 620 prickly, 617 Sikkim, 621 squirting, 606 snake, 620 star, 606, 620 wild, 606 Cucumis, 610 anguria, 617, 620, 622 dipsaceus, 613 key to principal species of, 617 melo, 617, 618 var. acidulus, 620 cantalupensis, 618 chito, 620 dudaim, 620 flexuosus, 618, 620 inodorus, 619 reticulatus, 618 saccharinus, 618 moschata, 620 sativus, 617, 620 Cucumis, sativus, anglicus, 621 Sikkimensis, 621 Cucurbit, 606 Cucurbita, 610, 612 key to important species of, 612 maxima, 612, 613 moschata, 612, 613 pepo, 612, 613 ovipera, 613 Cucurbitaceas, 606 key to principal genera of, 610 Culms, 72 Currant tomato, 587 Currants, American black, 319, 320 flowering, 319, 320 Buffalo, 319 European black, 319, 320 golden, 319 Missouri, 319 red, 320 white, 320 Cushaw, 612, 615 Cuticle, 44 Cutting lettuce, 633 Cyanophyceae, 63 Cyclanthera, 608 Cydonia, 388 oblonga, 388 varieties of, 388 Cymopteris, 532 Cynara scolymus, 639 Cyperaceae, 85 Cyphomandra betacea, 592 Cypress vine, 554 Cytase, 142 Cytoplasm, 6 Dahlia, 625 Dakota vetch, 429 Damson, 400 Dandelion, 628 Dangleberry, 547 Danish ball head cabbages, 332 INDEX 66 1 Datura, 559 Daucus, 533 carota, 533 varieties of, 535 Delaware grape, 501 Dent corn, 178, 180 Dermatogen, 17 Dewberry, 355 blackberry', 354 key to principal species of, 356 northern, 356 Pacific Coast, 352 ^ southern, 356 western, 356 Dextrins, 185 Diastase, 142 Dichogamy, 169 Dicot stem, 33 stem, growth in thickness of, 38 Dicotyledones, 63 Dimorphism, 292 Dioscorea batatas, 556 Dioscoreaceae, 556 Disk flowers, 627 Distichlis, 55 Dock, 284 Dolichos bean, 422 Domestic onions, 243 Double fertilization, 53 DracEena, 229 Dried apples, 383 Drosera, 47 Drumhead cabbages, 332 Drupe, 393 Drupaceae, 391 Duboisia hopwoodii, 600 Duckweed, 2 Dukes, 403 Durra, 196, 197 Durum wheat, 89, in, 112, 113 Dutch case-knife bean, 423 clover, 433 Dwarf bilberry, 546 Dwarf broom corn, 200 purple eggplant, 587 Dye- weed, 414 Ear, 162 Early or forcing radishes, 243 Earth apple, 639 Ecballium claterium, 606 Echinochloa, 88, 210 crus-galli, 210, 219, 220 frumentacea, 210, 220 Echinocystis lobata, 606 Ectoplasm, 6 Edible-podded pea, 418 Egg nucleus, 50 Eggplant, 585 common, 586 dwarf purple, 587 snake, 587 Egyptian cotton, 510 onions, 241, 242 millet, 213 Eichhornia speciosa, 16 Einkorn, 85, no Eleusine coracana, 210 Elodea, 29 Embryo, 96 sac, 50 Emmer, 89, in, 112, 113 Endive, 636 Endocarp, 58 Endodermis, 17, 57, 96, 102 English currants, 501 Entire wheat, 108 Epiblast, 104 Epidermis, 34 Epigaea repens, 543 Epiphyte, 28 Episperm, loi Equisetales, 64 Erect-eared barley, 147 Ericaceae, 543 Erigeron, 625, 628 662 INDEX Erinocyce figs, 275 Eriogonum, 285, 286 Eryngium, 530 Euchlsena mexicana, 181, 182 European black currant, 319, 320 cranberry, 544 gooseberries, 321 raspberry, 357 strawberry, 363, 364 Eurotia, 297 Evergreen or fire thorn, 366 Everlasting pea, 432 Exocarp, 58 "Eyes," 31 Fagopyrum, 286 emarginatum, 294 tataricum, 293 vulgare, 289 False flax, 326 Solomon's seal, 21 Fan barley, 146 Farkleberry, 543 Fennel, 533 Fenugreek, 467 Fermentation, 150 Fern plants, 62 Fertilization, 52 Festuca ovina, 79 pratensis, 76 Fiber flax, 473 of cotton, 514 Ficus, 267 aurea, 267, 268 benghalensis, 267 brevifolia, 268 carica, 268, 269 elastica, 252 religiosa, 267 Field cucumber, 621 pea, 418, 420 Fig, 267 Adriatic, 275 Fig, common, 269, 275 Cordelia, 276 Erinocyce, 275 Golden, 267 Mission, 275 San Pedro, 275 Smyrna, 275 wasp, 271 wild, 276 Filament, 48 Filicales, 64 Finger millet, 210 First patent, 108 Five-finger, 348 Flat Dutch cabbages, 332 onions, 241 -podded pea, 432 Flax, 48, 470 family, 469 fiber, 473 large-seeded, 473 Sicilian, 473 small-seeded, 473 Fleabane, 625, 628 Flint corn, 178, 180 Flour, kinds of, 108 Flower, apetalous, 55 complete, 55 hermaphroditic, 55 incomplete, 55 naked, 55 perfect, 55 pistillate, 55 staminate, 55 symmetry of, 53 Flowering bean, 423 crabapple, 379 raspberry, 254 Flowers, 48 incomplete, 55 parts of representative, Fly oats, 131 Foeniculum, 533 INDEX 663 Foliage beet, 310 Follicle, 58 Forage crops, 186 Foreign onions, 243 Fortunella, 476, 487 crassifolia, 4S9 hindsii, 489 japonica, 489 margarita, 488 Four-rowed barley, 144 Foxberry, 550 Foxtail millets, 211, 216, 219 grass, 211 Fragaria, 358 californica, 363 chiloensis, 363, 364 glauca, 363 vesca, 363, 364 virginiana, 363 Fraxinus, 551 Fruits, kinds of, 58 dehiscent, 58 dry, 58 fleshy, 59 indehiscent, 50 Fungi, 62 Furrow, 100 Fusarium, 570 Gall flowers, 271 Garden pea, 418 lemon, 620 radish, 341 tomato, 590 Garlic, 236, 237 Gaultheria, 543 Gaylussacia, 543, 545, 547 brachycera, 547 dumosa, 547 frondosa, 54 key to 547 rcsinosa, 547 a, 547 North American species of, Gaylussacia, ursina, 547 Geitonogamy, 51 Generative nucleus, 50 Genista, 414 Geotropism, 73 German alfalfa, 447 celery, 540 millet, 218, 219 Gherkin, 622 Giant clover, 453, 563 Girasole, 639 Gleditsia, 414 Gliadin, 105 Globe artichoke, 639 onions, 241 Globulin, 105 Glucose, 184 Glume, flowering, 80 Glumes, 79, 80 Gluten, 102, 106, 155 meal, 186 Glutenin, 106 Glycyrrhiza, 414 Golden currant, 319 fig, 267 wonder millet, 218, 219 Goldenrod, 625 Goober, 462 Gooseberry family, 316 gourd, 617 Gooseberries, 321 American, 321 European, 321 Goosefoot, 296 family, 296 Goose wheats, 113 Gossypium, 508 barbadense, 519, 520 hirsutum, 517, 518, 520 Gossypol, 524 Gourd, 610, 613 family, 606 gooseberry, 617 664 INDEX Gourd, winter, 615 Grafting, 36 Graham flour, 108 Grain, 83 coats, 96 Gramineae, 69 Granules, 8 Grape, 492 Catawba, 501 Concord, 501 Delaware, 501 family, 491 Muscat, 498 Niagara, 501 northern fox, 499, 500 Old World, 499 raisin, 499, 501 river bank, 499, 500 sand, 499, 500 southern fox, 499, 500 sugar, 185 summer, 499, 500 wine, 499, 501 Grapefruit, 485 Grass family, 69 awnless brome, 76 bunch, 76 buffalo, 70, 76 quack, 75 rice-cut, 70 tall oat, 75 Grasses, bulbous, 75 rhizome-bearing, 75 stoloniferous, 76 tufted, 76 Greasewood, 297 Green asparagus, 250 foxtail, 211, 219 gages, 398 Green-weed, 414 Grimm alfalfa, 447 Griottes, 404 Groove, 100 Grossulariacete, 316 Ground meristem, 34 Growing point, 57 Guard cells, 45 Guatemalan cotton, 512 Guinea squash, 585 Gumbo, 527 Gums, artificial, 185 British, 185 Guncotton, 525 Gymnospermae, 62 Hackling, hemp, 280 Hairs, basal, 92 Hairy vetch, 427, 430 Halophyte, 296 Head, 56 lettuce, 633 Hearts, 403 Heath family, 543 Hedysaras, 415 Helianthus, 628 tuberosus, 639 Hemp, 252, 276 sisal, 281 tow, 280 Hennequin, 281 Hepaticae, 64 Herb, 2 Hesperidium, 478 Heterostyly, 292 Hibiscus, 506 esculentus, 507, 527 syriacus, 508 High-bush blackberry, 354 blueberry, 547, 550 Hog millet, 213 Hollyhock, 508 Homalocenchrus, 70, 81 Homogamy, 169 Honduras rice, 206 Hooded barley, 136, 137, 145, 146 Hop, 2,Z, 252 INDEX 665 Hop, clover, 442, 449 -meal, 264 -tree, 475 - Hordcum, 88, 135 distichon, 135, 136, 137, 143, 145 erectum, 147 nudum, 146 nutans, 146, 147 zeocriton, 146 spontaneum, 148 vulgare, 144, coeleste, 145 . coerulescens, 145 hexastichon, 136, 137, 143, 144, 146 intermedium, 137, 143, 145, 146 nigrum, 145 pallidum, 143, 145, 146 trifurcatum, 136, 137, 145, 146 Horse millet, 213 nettle, 560 Horseradish, 345 Horsetails, 62 Hortulana plum, 400 Hosackia, 429 Hubbard squash, 614 • Huckleberry, 547 black, 547, 550 blue, 546, 547 box, 547 bush, 547 Carolina, 547 dwarf, 547 family, 543 high bush, 547 southern black, 544 swamp, 547 Hull-less Jerusalem barley, 145 oats, 130 Humulus, 252, 258 japonicus, 265 lupulus, 258 neomcxicanus, 265 Hungarian millet, 219 vetch, 430 Husk tomato, 592 Hyacinth, 229 bean, 422 Hyaloplasm, 6 Hybrid barley, 145 Hydrocotyle, 530 Hypocotyl, 57, 104 Ichang lemon, 487 Imperatricc plums, 399 Incomplete flowers, 55 Indian corn, 88 millet, 213 mustard, 340 tobacco, 600 India rubber plant, 252 Inflorescence, determinate or cymose, 56 indeterminate or racemose, 56 scar, 26 simple, 56 Integuments, 50 Intercellular spaces, 44 Tnternodes, 72 Intracalicary organs, of cotton, 513 Involucre, of cotton, 512 Ipomcea, 554, 555 batatas, 555 bona-nox, 554 pandurata, 554 purpurea, 554 Italian clover, 435 Jack bean, 422 Japan clover, 465 ivy, 33 millet, 213 rice, 206 Japanese apricot, 407 barnyard millet, 210, 220 buckwheat, 294 hop, 265 666 INDEX Japanese pear, 384, 385 or pot-herb mustard, 340 plum, 400 Jasminium, 551 Jerusalem artichoke, 628, 639 cucumber, 617 Jessamine, 551 Jimson-weed, 560 Jumbos, 464 Juncaceae, 85 Jute, 281 Kafir, 196, 197 Kale, 329, 330 Kalmia, 543 Keel, 415 Kidney bean, 433, 424 vetch, 429 King orange, 4S5 Kinkan, 487 Kinnikinic, 543 Kleinwanzlebener sugar beet, 308 Knaurs, 553 Knotberry, 350 Knotweed, 284, 286 Kochia, 297 Koeleria, 79 Kohlrabi, 330, 333 Kowliang, 197 Kuhnia, 627 Kumquat, 487 Hongkong wild, 489 Marumi, 489 Meiwa, 489 Nagami, 488 oval, 488 round, 489 Lablab, 422 Labrador tea, 543 Lactuca, 628 sativa, 629 angustana, 632 Lactuca, sativa, capitata, 633 intybacea, 633 romana, 633 scariola, 630 Ladino clover, 434 Lagenaria vulgaris, 613 Lamb's quarters, 296 Lamella, middle, 375 Lamina, 77 Large cranberry, 548 • leaf tomato, 590 -seeded flax, 473 Lathyrus, 414 Lawn grass, 70 Layering, 316 Leaf, beet, 301, 312 floral, 2 foliage, 2 scale, 2 scar, 26 stalk, 42 Leaflets, 44 Leafy-cluster blackberry, 354 Leaves, 42 compound, 44 development of, 42 foliage, 42 kinds of, 42 parts of, 42 simple, 44 structure of, 44 Leek, 232, 236, 238 Ledum, 543 Legume, 413 Leguminosas, 413 key to principal genera of, 416 Lemma, 80 Lemon, 481 Ichang, 487 Lenticel, 27 Lepidium, 326 Lespedeza striata, 465 Lettuce, 628 INDEX 667 Lettuce, asparagus, 632 cos, 633 cutting or cut-leaved, 633 garden, 629 head or cabbage, 633 key to types of, 632 Leucoplastids, 8 Lianas, ^:i Licorice, 414 Lignin, 36 Ligulate flowers, 627 Ligule, 78 Liguliflorae, 627 Ligustrum, 551 Lilac, 551 Liliaceae, 229 Lilium, 229 Lily, 229 family, 229 Lima bean, 423, 424 Lime, 483 Limequat, 483 Linaceae, 469 Linen, 473 Linoleum, 473 Linseed oil, 473 Linum, 470 catharticum, 469 usitatissimum, 470 Llanos, 69 Liverworts, 62 Lobelia inflata, 600 Lobfigs, 275 Locks, 514 Loco, 414 Locust, 414 bean, 422 Lodicules, 80 Lodging, 72 Loganberry, 358 Lombard plums, 399 Long-cluster blackberry, 354 Loose-cluster blackberry, 354 Lotus corniculatus, 466 Low black blueberry, 546 blueberry, 546 bush blueberry, 550 Luff a, 613 Lupines, 465 Lupinus, 465 Lupulin, 264 glands, 264 Lupuline, 266 Lycium, 559 Lycopersicum, 587 esculentum, cerasiforme, 587 grandifolium, 587, 588 pimpinellifolium, 587, 588 pyriforme, 587 validum, 587 vulgare, 590 Lycopodiales, 64 Macaroni, 118 wheats, 113 Macounastrum, 284 Maiz de coyote, 1 79 Maize, 88, 157 Male nuclei, 50 Mallow familj^ 505 Malting, 149 Malus, 366, 367 angustifolia, 379 baccata, 379 coronaria, 379 floribunda, 379 ioensis, 379, 381 key to principal species of, 379 soulardi, 379, 381 sylvestris, 379, 381 Malva, 507, 508 Malvacea;, 505 key to important genera of, 508 Mamme, 272 Mammoni, 272 668 INDEX Mammoth clover, 433, 439, 441 pumpkins and squashes, 615 Mandarin orange, 485 Mand's wonder forage plant, 213 Mane oats, 130 Mangels, 313 Mangel-wurzels, 313 Man-of-the-earth, 554 Marblehead squash, 614 Marigold, 625 Marrow squashes, 614 Marsh mallow, 506 Massecuite, 227 Mayberry, 358 Mazzards, 402 Meadow clover, 441 fescue, 76 foxtail, 79 Meadows, 69 Mealiness, in apple, 375 Medicago, 441 arabica, 442, 449 inermis, 451 falcata, 443, 447 hispida, 442, 452 conlinis, 452 denticulata, 452 reticulata, 452 key to principal species of, 442 lupulina, 442, 449 media, 447 sativa, 442, 447 polia, 448 Medics, 441 Mediterranean oats, 130 orange, 484 Medium barley, 137, 143, 145, 146 red clover, 441 Medulla, 18 Medullary ray, 35, 39 Megarhiza calif ornica, 610 Melilot, 453 Melilotus, 452 Melilotus, alba, 453, 454 altissima, 454 gracilis, 454 indica, 454 officinalis, 453, 454 speciosa, 454 Melon apple, 620 pear, 561 Melons, 618 cucumber, 620 Dudaim, 620 Mango, 620 netted, 618 orange, 620 pineapple, 618 pomegranate, 620 Queen Anne's pocket, 620 snake, 618 winter, 619 Mendelism, 421 Mendel's law, 421 Mericarp, 532 Meristem tissue, ;^^ Mesembryacea?, 299 Mesocarp, 58 Mexican bean, 424 grass, 182 Micrampelis, 608 JSIicropyle, 50, 57 Middlings, 108 Millet, 88, 210 African, 213 Aino, 218 barnyard, 210, 219 broom-corn, 210, 213 Egyptian, 213 foxtail, 21 r, 216 German, 218 Golden Wonder, 218 Hog, 213 Horse, 213 Hungarian, 219 Indian, 213 INDEX 669 Millet, Japan, 21 3 Ja])aiicsc barnyanl, 210, 220 key to principal economic t3'i)cs (species) of, 210 pearl, 211 proso, 210, 213 Siberian, 218 true, 210 ]\lilo, 88, 196, 197 Mirabelles, 400 Mission figs, 275 Missouri currant, 319 Monocot stems, 39 Monocotyledones, 62 Monolepis, 297 Moon-flower, 554 Mooting, 73 Moraceae, 252 Morellos, 404 Morning glory, ^^ family, 554 Morus, 252, 253 alba, 255 tartarica, 255 venosa, 255 key to principal species of, 255 multicaulis, 256 nervosa, 256 nigra, 255, 257 rubra, 255, 257, 258 Moss plants, 62 Mountain ash, 366 bramble, 351 cranberry, 550 mahogany, 348 sorrel, 284 spinach, 299 timothy, 223 tobacco, 600 Mulberry, 252, 253 black, 255, 257 family, 252 paper, 254 Mulberry, red, 255, 257, 258 Russian, 255 white, 25s Mule flowers, 271 Multiplier onions, 242 Multipliers, 241 Mung bean, 423 Muscat grape, 498 Musci, 64 jMusk cucumber, 620 Muskmelon, 618 IMustard, 327 black, 327, 339 brown, 339 Chinese, 340 family, 323 Indian, 340 Japanese, 340 pot-herb, 340 white, 327, 340 Myrobalan plum, 400 Myxomycetes, 63 Naked oats, 130 wheats, in, 112 Nankin cotton, 517 Nardus, 81 Narbonne vetch, 429 Narrow- leafed crab-apple, 66, 379 leaved vetch, 428 Navel orange, 484 Nectaries, of cotton, 512 Nectarine, 410 Nepal barley, 145 Nepenthes, 47 New Zealand spinach, 299 Niagara grape, 501 Nicotiana, 560, 596 alata, 600 glauca, 596 persica, 600 quadrivalvis, 600 rustica, 600 670 INDEX Nicotiana, tabacum, 597 tomentosa, 596 wigandioides, 596 Nodding barley, 147 Node, 22 Nodes, 72 Non-saccharine sorghums, 196 Northern dewberry, 65, 356 fox grape, 499, 500 Nucellus, 50, 102 Nucleoli, 6 Nucleus, 6, 8 Nurse crop, 149 Oats, 88, 89, 123 Abyssinian, 130 Algerian, 131 animated, 131 banner, 130 fly, 131 hull-less, 130 mane, 130 Mediterranean, 130 naked, 130 panicle, 130 rough, 131 short, 130 side, 130 single, 126 sterile, 131 Tatarian, 130 twin, 126 wild, 130 Ochrus, 432 Ocrea, 284 Oil cake, 473 meal, 473 Okra, 527 Old World plums, 397 Oleaceae, 551 Olea europooea, 551 Oleomargarine, 524 Olive, 551 family, 551 Onion, 231, 240 common, 232, 237 Egyptian, 241, 242 multiplier, 241, 242 perennial tree, 243 potato, 241 top, 241, 242 tree, 241, 242 Welsh, 231, 239 Onions, types of, 241 composition of, 243 uses of, 244 Onobrychis vicia;folia, 465 Ophioglossales, 64 Orache, 299 Orange, blood, 484 Calamondin, 487 common, 484 king, 485 mandarin, 485 Mediterranean, 484 navel, 484 Satsuma, 485 Seville, 487 sour, 487 Spanish, 484 sweet, 484 trifoliate, 489 Unshiu, 485 Organs, 4 absorptive, 4 reproductive, 4 Ornamental beet, 301 Ornithopus sativus, 465 Oryza, 81, 87, 88 glutinosa, 204 granulata, 206 officinalis, 206 sativa, 200, 206 utilissima, 206 communis, 206 INDEX 671 Oryza, sativa, miniita, 206 Osage orange, 252 Ovary, 48 inferior, 54 superior, 54 wall, loi Ovules, 48, 50 Oxypolis, 530 Oxyria digyna, 284 Oyster plant, 633 Spanish, 635 Pacific Coast dewberry, 352 Painted lady bean, 423 Palea, 80 Palet, 80 Palisade tissue, 44 Panicle, 56, 79 oats, 130 Panicum, 210 miliaceum, 210, 213 compactum, 215 contractum, 215 effusum, 215 Papaveraceae, 326 Paper mulberry, 252, 254 Pappus, 627 Papyrus papyrifera, 252, 254 Parsley, 539 Parsnip, 536 Parthenocarpy, 374 Parthenocissus, 492 Pastinaca, 533 sativa, 536 Pasture crop, 149 Patent flour, 108 Patanas, 69 Pea, 417 chick, 467 common sweet, 432 edible-podded, 418 family, 413 everlasting, 432 Pea, field, 418, 420 flat-podded, 432 garden, 418 perennial, 432 shelling, 418 sugar, 418 Tangier, 432 wild, 432 Peach, 407 Peacock barley, 146 Peanut, 462 butter, 464 meal, 465 oil, 465 Pear, 384 Chinese, 384, 385 common, 384, 385 Japanese, 384, 385 sand, 384, 385 tomato, 587 Pearl barley, 149 millet, 211 Peepul tree, 267 Pencilaria, 213 Pennisetum, 88, 210 spicatum, 211 Penny cress, 326 Pepino, 561 Pepo, 608 Pepper, 592 Cayenne, 595 Tabasco, 595 vine, 492 Perennial, 20, 70 pea, 432 tree onions, 243 Perianth, 49 Periblem, 17 Pericarp, loi Pericycle, 17 Peridrigon plums, 399 Perisperm, 102 Perpetual strawberry, 363, 364 672 INDEX Persian clover, 433 tobacco, 600 Persicaria, 286 Peruvian alfalfa, 447 Petals, 48 Petiole, 42 Petunia, 559 Phjeopbyceaj, 63 Phaseolus, 421 angularis, 423 aureus, 423 key to principal species of, 423 lunatus, 423, 424 macrocarpus, 424 multiflorus, 423 vulgaris, 423, 426 nanus, 426 Phleum, 222 alpinum, 223 pratense, 222 Phloem, 18, 35 elements, functions of, 36 parenchyma, 35 Photosynthesis, 46 Phycomycetes, 64 Phylloxera, 499 Phylogeny, 83 Physalis, 559 Pickles, 621 Pie plant, 286 Pileole, 104 Pistil, 48, 51 Pistillate inflorescence, 55 Pisum, 416, 417 sativum, 418 Pitcher plants, 47 Pitching, 150 Pith, 18, 39 Placenta, 50 Placenlation, 53 Plant body, i fundamental internal structure of, 4 cell, 4 Plant body, cell, discover)' of, 4 structure of, 6 nomenclature, 64 Plastids, chloroplastids, 8 chromoplastids, 8 leucoplastids, 8 Plerome, 17 Plum, American, 397, 400, 401 Chicasaw, 401 family, 391 hortulana, 400 Japanese, 400 key to principal species of, 397 myrobalan, 400 old world, 397 tomato, 590 Plumy asparagus, 246 Poa pratensis, 7c Poaceae, 69 Pod, 58 corn, 178, 180 Polar nuclei, 50 Polish wheat, in, 112, 113 Pollen grains, 48, 52 mother cells, 50 tube, 52 Pollination, 51 Polygonacea;, 284 key to principal genera, 286 Polygonum, 284 Pomaceae, 366 key to important genera of, 367 Pome, 366 Pomelo, 485 Poncirus, 476; 489 trifoliata, 489 Pop corn, 178, 180 Poppy family, 326 Pot-herb mustard, 340 Potamogeton, 29 Potato, 561 family, 559 onions, 241 INDEX 673 Potentilla, 348 \ Poulard wheat, iii, 112 Prickly ash, 475 cucumber, 617 Privet, 551 Profichi, 272 Prophyllum, So Prop roots, 16, 159 Proso, 213 millet, 210 Protandry, 170 Protease, 142 Proteose, 105 Protogyny, 170 Protoplasm, 9 Protoplasmic membrane, 6 Protoplast, 6 Prunes, 398 Prunus, 394 americana, 400 amygdalus, 410 angustifolia, 401 armeniaca, 405 avium, 402 besseyi, 404 cerasifera, 400 cerasus, 402, 403 cuneata, 404 dasj'carpa, 407 domestica, 39S emarginata, 404 hortulana, 400 insitilia, 399 key to main groups of, 394 mahaleb, 404 mume, 407 munsoniana, 401 nigra, 401 pennsylvanica, 404 persica, 407 pumila, 404 sibirica, 407 triflora, 400 43 Psedera tricuspidata, S3 Pscudomonas radicicola, 413 Psilotalcs, 64 Ptelea, 475 Pteridophytes, 62 Pumpkin, 613 field, 613 mammoth, 615 Valparaiso, 615 Purple apricot, 407 cane raspberry, 357 clover, 436 vetch, 428 Pyrus, 384 communis, 384, 3S5 serotina culta, 384, 385 Quackgrass, 21, 70 Quamoclit quamoclit, 554 Quince, 388 Rabbit-brush, 625 Raceme, 56, 78 Rachilla, 79 Rachis, 79, 92 Radicula, 344 armoracia, 345 nasturtium-aquaticum, 345 Radicle, 57 Radish, 341 garden, 341 rat-tailed, 343 wild, 342 Ragi millet, 210 Raisin grape, 499, 500 Raisins, 501 Raphanus, 341 caudatus, 343 raphanistrum, 342 sativus, 341 Raspberry, 357 American red, 357 black cap, 357 674 INDEX Raspberry, European red, 357 key to princijjal species of, 357 purple-cane, 357 Rat-tailed radish, 343 Ray flowers, 627 Receptacle, 49 Red cabbages, 332 clover, 433, 435 currant, 320 mulberry, 255, 257, 258 Peruvian cotton, 517 Repeated germination, 109 Reproductive activity, i Retting, 279 Rheum, 289 palmatum, 289 undulatum, 289 Rhizbctonia, 569 Rhizomes, 29, 75 Rhododendron, 543 Rhodophyceae, 63 Rhubarb, 286 Ribes, americanum, 319, 320 aureum, 319, 320 grossularia, 319, 321 key to important species of, 319 nigrum, 319, 320 oxycanthoides, 319, 321 rubrum, 319, 320 vulgare, 319, 320 Rice, 88, 202 Canada, 206 cultivated, 206 large-kerneled, 206 small-kerneled, 206 wild, 206, 207 River bank grape, 499, 500 Robinia, 414 Rockmelons, 618 Root cap, 17 crown, 157 hair, effect of external factors upon development of, 20 Root cap, structure of, 20 -hair zone, 19 primary, 10 sheath, 10, 103 system, effect of environment upon character of, 14 primary, 91 temporary, 91 systems, 2, 10 adventitious, 11 development of, 10 fibrous, 10, II primary, 10 tap, 14 temporary, 10 tubercles, 413 Roots adventitious, 11 air, 16 classification of, based upon their medium of growth, 16 general characteristics of, 15 length of life of, 2 1 seminal, 10 soil, 16 structure of, 16 tap, 14 water, 16 work of, 14 Rootstocks, 29, 75 Rosacea?, 348 key to important genera of, 350 Rose family, 348 of Sharon, 508 Rough oats, 131 Rubus, 350, 353 argutus, 354, 355 bernardinus, 357 chamaemorus, 350 cuneifolius, 354, 355 glaucifolius, 357 idaeus, 357 invisus, 356 key to groups of, 353 INDEX 67; Riiljus, k'ucodcrmis, 357 microphyllus, 35S ncglcctus, 35.S nigrobaccus, 354 albinus, 354 sativus, 354 occidentalis, 357 strigosus, 357, 358 Irivialis, 356 villosus, 354, 356 roribaccus, 356 vitifolius, 352, 356, 358 Rue family, 475 Rumcx, 284 Runner, 13, 32, 76, 358 Rushes, 85 Russian mulberry, 255 thistle, 47, 296 vetch, 430 Rutabaga, 337 Rutaceae, 475 kej' to important genera of, 476 Rye, 88, 89, 153 Saccharum ofiicinarum, 225 Sachs, 177 Sage, 625, 628 Sainfoin, 465 Sake, 207 Salicornia, 297 Salsify, 628 , black, 635 Spanish, 635 yellow-flowered, 635 Salsola, 296 Saltbush, 296 Salt-grass, 55 Salt wort, 47 Samara, 551 Sand bur, 560 blackberry, 354 grape, 499, 500 pear, 384, 385 San Pedro figs, 275 Sanicula, 532 Sarcobatus, 297 Sarracenia, 47 Sauerkraut, ^^2 Satsuma orange, 485 Savannahs, 69 Savoy cabbages, 332 Scales, 78 Scallop, 613 Scarlet clover, 433, 435 runner bean, 423 strawberry, 363 vetch, 428 Schizomycetes, 63 Schizophytes, 63 Schuster, 84 Scientific name, 64 versus common name, 66 names, descriptive nature of, 66 Scion, 36 Scorzonera hispanica, 635 Scouring rushes, 62 Scutching, hemp, 280 Scutellum, 104 Sea Island cotton, 520, 521 Sea-kale beet, 312 Secale, 88, 153 anatolicum, 155 cereale, 89, 153 montanum, 155 Second patent, 108 Secondary cortex, 38 Sedges, 85 Seed ball, 306 coats, 57 germination of, 59 leaves, 59 plant body, size and form of, 2 principal parts of, 1 Seeds, 57 Seedlings, 57 Self-fertility, 372 676 INDEX Self-sterility, 372, 497 Seminal roots, 103 Semolina, 118 Sepals, 48 Sequoias, Giant, 2 Serradella, 465 Service berry, 366 Setaria, 210 Seville orange, 487 Shaddock, 485 Shaftal clover, 433 Shallot, 237, 238 Shallu, 196, 197 Shank, 163 Shantz, 117 Sheath, 77 Sheep's fescue, 79 Shelling pea, 418 Shepherd's purse, 326 Shoot system, 2 development of, 22 Short oats, 130 Shrub, 2 Siberian apricot, 407 crabapple, 379 millet, 218, 219 vetch, 430 Sicilian flax, 473 Sickle alfalfa, 447 Sicyos angulatus, 606 Sicyosperma gracilis, 610 Sieva bean, 423, 424^ Sieve tubes, 35 Sikkim cucumber, 621 Silage, 186 Silicle, 325 Silique, 325 Silks, 171 Silo, 186 Silver beet, 312 hull buckwheat, 294 Single oats, 126 Sisal hemp, 281 Sitopyros, no Six-rowed barley, 144 Small cranberry, 548, 549 Small-seeded flax, 473 Smilax, 244 Smith, 175 Smother crop, 149 Smyrna figs, 273, 275 Snake cucumber, 620 eggplant, 587 Soapweed, 229 Soft corn, 178, 180 Soja bean, 456 Solanaceae, 559, key to important genera of, 560 Solanum, 560 carolinense, 560, 561 chiloense, 561 commersonii, 561 dulcamara, 560, 561 elaeagnifolium, 560 immite, 561 jamesii, 561 key to important species of, 561 maglia, 561 melongena, 561 depressum, 587 esculentinum, 586 serpentinum, 587 muricatum, 561 nigrum, 560, 561 rostratum, 560, 561 triflorum, 561 tuberosum, 560, 561, 562 Solidago, 625 Sonchus, 625 Sophia, 326 Sophora, 415 Sorbus, 366 Sorghum, 88 Sorghums, 191 key to principal types, 197 origin of, 197 INDEX 677 Sorghums, uses of, 199 Sorgo, 196, 197 Soulard crabapple, 379, 381 Sour orange, 487 Southern dewberry, 356 fox grape, 499, 500 Sow-thistle, 625 Soy bean, 456 Soya, 455 max, 456 Spanish bayonet, 229 moss, 28 needles, 625 orange, 484 salsify, 635 Spathe, 234 Spelt, 89, III, 112, 113 wheats, in Sperm nuclei, 50 Spermatophytes, 62 Sphenophyllales, 64 Spike 56, 79 Spikelet, 78, 79, 80 Spinacea, 298 oleracea, 298 Spinach beet, 312 common garden, 300 key to groups of, 300 mountain, 299 New Zealand, 299 Spines, 33 Spiraea, 348 Spongy parenchyma, 44 Spotted bur clover, 442, 449 Spreading oats, 130 Spur, 23 Spurs, 367 Squash, 610 Canada crookneck, 610, 612 Hulibard, 612, 614 mammoth whale, 615 marblchead, 610, 612, 614 marrow, 614 Squash, summer, 613 turban, 610, 612, 614 Valparaiso, 615 Squirting cucumber, 606 Stages, ripening, 97 Stamens, 48 Staminate inflorescence, 55 Standard, 414 broom corn, 200 patent, 108 Star cucumber, 606, 620 Starches, 177 Starchy endosperm, 103 sweet corn, 178, 180 Strawberry tomato, 592 Stele, 17 Stem, of dicot, 33 Stems, 22 aerial, 2 classification of, based upon their medium of growth, 28 general characteristics of, 26 structure of, 33 underground, 2 work of, 41 Steppes, 69 Stewart, 167 Stigma, 48 Stipules, 42 Stock, 36 Stolon, 32 Stomata, 45 Stone crop, 47 Stooling, 22, 73 Straight bread flour, 108 Strawberry blite, 296 Chilean, 363, 364 European, 363, 364 everlasting, 364 perpetual, 363, 364 scarlet, 363 Virginian, 363 wood, 364 678 INDEX Streamside grape, 66 Streptochasta, 81, 84 Sturtevant, 159, 167, 178 Stylar canal, 168 Style, 48 Stylopodium, 531 Succory, 635, 636 Suckers, 160 Sugar beet, 300, 301 Sugar cane, 225 pea, 418 Sultanas, 501 Summer figs, 275 grape, 499, 500 radishes, 243 wood, 40 Sundew, 47 Sunflower, 625, 628 Swedes, 337 Swedish clover, 433, 434 Sweet clover, 452 white, 454 yellow, 454 corn, 178, 180 orange, 484 pea, leaf, 43 potato, 555 sorghums, 196 Swiss chard, 312 Synconium, 268 Synergids, 50 Systema Naturae, 61 Systematic botany, 60 Syringa, 551 Tabasco pepper, 595 Tall bilberry, 547 Tangelo, 485 Tangerine, 485 Tangier pea, 432 Tangleberry, 547 Tansy mustard, 326 Tap root system, 13 Taraxacum, 628 Tares, 429 Tassel, 55, 162 Tatarian oats, 130 Tatary buckwheat, 293 Teas' weeping mulberry, 256 Tempering, 107 Tendrils, 33 Teneriff^e, 243 Teosinte, 166, 181, 182 Testa, loi Tetragonia expansa, 299 Thallophytes, 62 Thallus, I plants, 62 Thermopsis, 414 Thin-leaved bilberry, 544 Thistle, 625, 628 family, 625 Thlaspi, 326 Thorn apple, 366, 367 Tillandsia usneoides, 28 Tillering, 22, 73, 74 Timothy, 75, 222 Tissue, 4 Tobacco, 596 Australian, 600 Indian, 600 mountain, 600 Persian, 600 "wild," 600 Tomato, 587 cherry, 587, 590 currant, 587 garden, 590 husk, 592 key to types of cultivated, 591 large leaf, 590 pear or plum, 587, 590 strawberry, 592 tree, 592 "Pright, 587, S90 Toothed bur clover, 442, 452 INDEX 679 Topinambour, 639 Top onions, 241, 242 Torch-wood, 475 Torus, 49 Toxylon pomiferum, 252 Tracheal tubes, 36 Tracheids, 36 Tragopogon, 628 p'orrifolius, 633 pratensis, 635 Trailing arbutus, 543 Transpiration stream, 47 Tree, 2 onions, 241, 242 tomato, 592 Trifoliate orange, 489 Trifolium, 66, 432 ale.xandrinum, 433 hybridum, 433, 434 incarnatum, 433, 435 key to principal species of, 433 medium, 433, 441 pratense, 433, 436 perenne, 439 repens, 433 suaveolens, 433 Trigonella foenum-groecum, 467 Tripping, of alfalfa flowers, 444 Triticum, 88, 91 oegilopoides, 112, 116 aestivum, iii, 112, 114, 116 boeoticum, 112 capitatum, 116 compactum, iii, 112, 114, 116 dicoccum, iii, 112, 113, 116 dicoccoides, 114, 115, 116 durum, in, 112, 113, 116 hermonis, 114 monococcum, no, in, 112 ovata, no polonicum, in, 112, 113, 116 spclta, in, 112, 113, 116 J thaoudar, 112 Triticum, turgidum, in, 113, 116 Tube nucleus, 50 Tuberization, fungus theory of, 569 Tubers, 30, 31 Tubuliflorae, 627 Tulip, 229 Turban squash, 614 Turkestan alfalfa, 447 Turnip, 65, 335 common, 335 Swede, 337 Turnip-rooted celery, 540 Twin oats, 126 Two-rowed barley, 145 Umbel, 56, 234, 530 Umbelliferae, 530 key to genera of economic impor- tance, 533 Unshiu orange, 485 Upland cotton, 510, 520 Upright tomato, 587, 590 Utricle, 297 Vaccinium, 543, 545 angustifolium, 546, 550 arboreum, 543 atrococcum, 547, 550 caespitosum, 546 canadense, 66, 546, 550 corymbosum, 547, 550 key to chief fruit-bearing species of, 546 macrocarpon, 546, 548 membranaceum, 544 myrtillus, 546 nigrum, 546, 550 ovalifolium, 547 oxycoccus, 546, 549 vacillans, 546, 550 virgatum, 544 vitis-idsea, 546, 550 Vacciniaceae, 543 68o INDEX Vacuole, 7 Variegated alfalfa, 447 Vascular bundles, 35 elements, 35 Vegetative activity, i Velvet bean, 422 Vetch, 414, 426 . black bitter, 428 crown, 429 Dakota, 429 hairy, 427, 430 Hungarian, 430 kidney, 429 Narbonne, 429 narrow-leaved, 428 purple, 428 Russian, 430 scarlet, 428 Siberian, 430 villous, 430 woolly-podded, 429 Vetchling, 432 Vexillum, 414 Vicia, 414, 426 angustifolia, 428 atropurpurea, 428 dasycarpa, 429 ervilia, 428 faba, 427, 429 fulgens, 429 key to important species of, 427 narbonnensis, 429 sativa, 427, 429 villosa, 427, 430 Vigna, 458 catjang, 458 sequipedalis, 458 sinensis, 458, 460 Villous vetch, 430 Vilmorin sugar beet, 308 Vine peach, 620 Vinegar, 383, 503 Virginia creeper, 16, 33 Virginian strawberry, 363 Vitaceae, 491 key to important genera of, 492 Vitis, 492 aestivalis, 499, 500 bourguiniana, 501 labrusca, 499, 500 riparia, 499, 500 rotundifolia, 499, 500 rupestris, 499, 500 vinifera, 499 Wakefield cabbages, 332 Washingtonia, 532 Water cress, 345 hyacinth, 16 lily, 29 Watermelon, 610, 622, 623 types and varieties, 623 Welsh onion, 232, 237, 239 West Indian gherkin, 617 Western crabapple, 379, 381 dewberry, 356 Wheat, 88, 89, 91 classification of the types of, no club. III, 112, 113, 114 common bread, in, 112, 113, 114 durum, 89, in, 112, 113 grain, microscopic section, 100 hard, 106 naked, in, 112 Polish, ni, 112, 113 Poulard, in, 112, 113 soft, X06 spelt. III, 112, 113 White blackberry, 354 clover, 433, 441 currant, 320 mulberry, 255 mustard, 327, 340 Whortleberry, 546 Wild barnyard grass, 210 beet, 301 INDEX 68l Wild cabbage, 328 cotton, 520 cucumber, 606 emmcr, 114, 115 fig, 276 goose wheats, 113 oats, 130 pea, 432 radish, 342 rice, 207 tobacco, 600 Windberry, 550 Windsor bean, 427, 429 . Wine grape, 499, 500 Wines, 502 Wings, 415 Winningstadt cabbages, ^3^ Winter gourd, 615 radishes, 243 Wolberry, 550 Wood, 36 elements, functions of, 37 fibers, 36 parenchyma, 36 strawberry, 364 Woolly-podded vetch, 429 Wormwood, 625, 628 Xanthoxylum, 475 Xenogamy, 52, 95 Xylem, 18, 36 Yams, 556 Yarrow, 625 Yellow egg plums, 399 -flowered alfalfa, 447 salsify, 635 Young dicot stem, ^s Yucca, 229 Zanta currants, 501 Zea, 87, 157 canina, 179 mays, 158, 17S amylacea, 178, 180 amylea-saccharata, 178, 180 curagua, 179 everta, 178, 180 hirta, 179 indentata, 178, 180 indurata, 178, 180 japonica, 179 key to "species groups" of, 180 saccharata, 178, 180 tunicata, 178, 180, 182 ramosa, 179 Zigzag clover, 433, 441 Zizania aquatica, 206 miliacea, 207 Zygote, 52 ■ k ^, •"oo^ on" \^ .#■ x^^ -^t. xO^^ -/-„ ^^^\ ,0 ^^ rO •v\ %./ ^^ V^ ■..■A'''i ""'^/fc^" >'-.^X -^z. v^ .■.^' ■>», 'A v>' .0 o^ if o v^^^ '^. ^'^ >• A ,. ^ ■ « .^^" '^^. 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