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Full text of "The botany of crop plants; a text and reference book"

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THE 
BOTANY OF CROP PLANTS 



ROBBINS 



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THE 

BOTANY OF CROP PLANTS 

A TEXT 
AND REFERENCE BOOK 



BY 
WILFRED W. ROBBINS, Ph. D. 

PROFESSOR OF BOTANY, COLORADO AGRICULTURAL COLLEGE 



WITH A GLOSSARY AND 
263 ILLUSTRATIONS 



PHILADELPHIA 

P. BLAKISTON'S SON & CO- 

1012 WALNUT STREET 



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Copyright, 1917, by P. Blakiston's Son & Co. 



THE MAPLE PRESS YORK PA 



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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 as agricultural 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. 



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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 obliga- 
tion. Bailey's Cyclopedia of Horticulture has been indis- 
pensable and has been called into use frequently. The 
writer has also called upon the publications 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 laken 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 made 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 



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CONTENTS 

PART I 

CHAPTER I.— The Seed Plant Body. 

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 — Effect 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 — Greneral 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.— Leaves. 

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 Seedijngs. 

Development of the Seed — Development of the Fruit — Fruit 
and Seed Distinguished — Kinds of Fruits — Germination of 
the Seed ' 57-59 



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VIU CONTENTS 

CHAPTER VIII. — The Classification and Naming or 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^ (Poacke) 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 1 22-134 

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 135-152 



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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 i53~is6 

CHAPTER XIV.— Zea (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 Com— Variation in the Com Plant — Results of Self-fertiliza- 
tion in Corn — ^The Mature Grain of Com — Corn Starch 
Distinguished from the Other Common Starches — Germina- 
tion of Com — Classification — Key to "Species Groups" of 
Com — Origin of Maize — Environmental Relations — Uses of 
Cora — ^Production of Com — References 157-190 

CHAPTER XV. — Andropogon Sorghum (Sorghums). 

Habit of Plant, and Roots — Stems and Leaves — Inflorescence 
— Spikelets and Flc^wers — 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 XVI.— 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 2 10-2 11 

Pennisetum glaucum (Pearl Millet) — Stem — ^Leaf— Inflores- 
cence — Spikelet and Flower — Pollination — Mature Grain — 

Varieties — Origin 211-213 

Panicum mOiaceum (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 — 
T)^pes and Varieties of Foxtail Millet — Key to Principal Types of 
Foxtail Millets (Chaetochloa italica) — Origin of Foxtail Millet. 216-219 



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X CONTENTS 

Echinochloa Cms — galli (Barnyard Grass or Barnyard 
Millet) — Habit, Stems, Leaves — Inflorescence, Spikelet, 

Flowers, and Fruit — Distribution 219-220 

Echinochloa f rumen tacea (Japanese Barnyard Millet) 219-220 

En\aronmental Relations — Uses of Millets — References 220-221 

CHAPTER XVITI.— 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.— LiLiACEiE (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 Allium 231-237 

Allium sativum (Garlic) 237 

Allium porrum (Leek) ^ 238 

Allium schcenoprasum (Chives or Gives) 238 

Allium ascalom'cum (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^ (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 



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CONTENTS XI 

Humulus (Hop). Humulus lupulus (Common Hop) — Root — 
Stems — Leaves — Inflorescences — Flowers — Pollination, 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 — 

Geographcal Distribution, and Economic Importance 267-269 

Ficus cariica (Common Fig) — Habit of Plant, and Stem — 
Leaves — Inflorescence, and Flowers — Pollination — Crops of 
Fruit in Caprifigs — Caprification — The Mature Fruit — Geo- 
graphical — Tjrpes 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 XXIL— PoLYGONACE^ (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 XXIIL— CHENOPODiACEiE (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 — ^Types 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 313-31 5 



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Xll CONTENTS 

CHAPTER XXIV.— GROssuLARiACEiE (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 (^enus Brassica 327-328 

Brassica oleracea (Cabbages, etc.) — Wild Cabbage — Cultivat- 
ed Types of Cabbages— Key to Cultivated Types of Cabbage. 3 28-330 

Brassica oleracea var. viridis 330 

Brassica oleracea var. gemmifera (Brussels Sprouts) — Types 

—Uses 33^331 

Brassica oleracea var. capitata (Common Head Cabbage) — 

Types — Key to Types of Head Cabbage — Uses 331-333 

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 — 339-34© 

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.— RosACEiE (Rose Family). 

Leaves — Inflorescence — Flowers — Fruit — Key to Important 

Genera of Rosaceae 348-350 

Rub us (Raspberry, Blackberry, Dewberry) — Stems — 
Propagation — ^Leaves — Inflorescence — Flowers — Pollination — 



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CONTENTS XUl 

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 354-355 

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 
ocddentalis — Rubus idaeus — Rubus strigosus — Rubus stri- 

gosus X R. ocddentalis — The Loganberry — Mayberry 355-358 

Fragaria (Strawberry) — Roots and Stems — Leaves — Inflores- 
cence and Flowers — Fertilization, and Devdopment of the 
Fruit — ^The Mature Fruit — Geographical — Principal Fruit- 
bearing Spedes — Key to Prindpal Spedes of Fragaria — 
Fragaria virginiana — Fragaria vesca — Fragaria chiloensis — 
Varieties — Origin of New Varieties — ^Uses — References 358-365 

CHAPTER XXVII.— PoMACEiE (Apple Family). 

Habit, Leaves — Inflorescence — Flowers — Fruit — Geographical 

— Key to Important Genera of Pomaceae 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 Devdopment — Key to Principal 
Spedes of Mains — Malus floribunda — 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— DRUPACE.E (Plum Family). 

Habit, Stems — ^Leaves — Flowers — Fruit 391-394 

Prunus — Key to Main Groups of Genus Pninus 394 

Plums — Stems — ^Leaves — Inflorescence — Flowers — Fertiliza- 
tion — Fruit — Classification of Plums — Key to Principal 

Spedes of Plums 394-397 

Discussion of Species — Prunus domes tica — Prunus insititia— 



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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 410-41 2 

CHAPTER 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 — 



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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 

Medicago 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 

M^lilotus 452-454 

Melilotus alba (White Sweet Clover) — Description 454 

Melilotus 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.. 458-460 
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 Flax) — Habit, Root — Stem — 
Flax Fibers — ^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 Family). 

Description — Key to Important Genera of Rutaceae 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 



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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 (Trifoliate Orange) — Description — A Hardy Orange.489 
References 489-490 

CHAPTER XXXIL— ViTACEiE (Grape Family). 

Family Description — Geographical — Key to Important 

Genera 491-492 

Vitis (Grape) — Stems — ^Leaves — Inflorescence and Flowers — 
Opening of Flower and Pollination — Self-sterility — 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 Famtly). 

Habit — ^Leaves — Flowers — Fruit and Seeds — Geographical — 
Economic Importance — Key to Important Genera of Mal- 
vaceae. ., 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, Gumbo) — Description — Geo- 
graphical — Tjrpes — Uses 527-528 

References < 528-529 



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CONTENTS XVll 

CHAPTER XXXIV.— UMBELUFERiE (Carrot Family). 

Stems and Leaves — Inflorescence and Flowers — Fruit — 

Geographical — Key to Genera of Economic Importance 530-S33 

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 53^53^ 

Apium (Celery and Parsley) — Generic Description — Geo- 
graphical — Key to Principal Species of Apium 538^539 

Apium petroselinum (Parsley) — Description— Varieties S39-540 

Apium graveolens (Celery and Celeriac) — Description — Geo- 
graphical — Types and Varieties — Uses 540-542 

References 542 

CHAPTER XXXV.— VAcaNiACE^ (Huckleberry Family). 

Habit — ^Leaves — Inflorescence and Flowers — Fruit S43-S4S 

Vacdnium — Pollination — Fruit — Geographical — Key to Chief 

Fruit-bearing Species of Vaccinium 545-547 

Gaylussacia (Huckleberry, Tangleberry, Dangleberry) — 
Description — Geographical — Key to North American Species 

of Gaylussacia 547 

Cranberries — Vaccinium macrocarpon — ^T)rpes — Vaccinium 

oxycoccus, Vaccinium vitis-idaea 548-550 

Huckleberries and Blueberries 550 

References 550 

CHAPTER XXXVI.— Oleaceje (Olive Family). 

Family Description — Geographical, and Economic Impor- 
tance 551 

Olea europoea (Olive) — Description — Seed Germination — 
Propagation— Uses 55^-553 

CHAPTER XXXVII.— CoNVOLVULACKB (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 — T)rpes and Varieties — 
Leaf Shape as a Basis of Classification — Uses — References. . 555-558 

CHAPTER XXXVIIL— SoLANACEJE (Potato Family). 

Habit of Plants — Leaves — ^Inflorescence and Flowers — Fruit 

— Key to Important Genera 559-560 

Solanum — Habit — ^Leaves — Inflorescence, and Flowers — 

FTuit — Geographical — Key to Important Species of Solanum.. 560-561 



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XVm 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 — Medulla — 
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 — ^T>'pes and 
Varieties — Composition — Curing Tobacco — The Tobacco In- 
dustry—References 597-605 

CHAPTER XXXIX.— CuctJRBiTACE^ (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 



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CONTENTS XIX 

Cucumis melo (Muskmelon, Cantaloupe, Melons) — Descrip- 
tion — Botanical Varieties of Cucumis melo 618-620 

Cucumis sativus (Cucumber) — Description — Geographical — 

— Closely Related Forms — Types — Pickles 620-622 

Cucumis anguria — 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.— CoMPOSiTiE (Thistle Faiuly). 

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 

Cidiorium (Chicory or Succory, and Endive) — Description — 

Geographical 635 

Cichorium intybus (Chicory or Succory) — Description — 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 641-65 1 

Index 653 



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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. 



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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 life 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 structiural 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 siurface 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 California; one individual, the General Sherman 
"big tree,'' measures 279.9 f^^^ ^ 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 



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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 grotmd. 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. 



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CHAPTER II 

FXJNDAMENTAL 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 r6le 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 imits — the cells. 

The Plant Cell. — Discovery of the Cell. — The discovery of 
the plant cell is attributed to Robert Hook^, 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 aUke 
in size and shape, and fitting closely together. It happens 

4 



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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 clings 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. 

Tlie 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 imits, 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 life 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 ability of the individual cells 
to Uve and reproduce when separated from its neighbors. In 



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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 fimctions more or less independently of its neighbors. 
The physiological unit of the plant is the cell. 

Tlie 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- 
living 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. 



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FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY ^ 

These spaces are called vacuoles. However, one must not 
think of the cell-sap spaces m 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. — i4, 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 solution. {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. 



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Plant ceU 



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: 

Cell wall (non-living) 

f Protoplasmic membrane (living) 

I Nucleus (living), containing one or more nucleoli 

protoplast. { { plastids (living) 

I P , I granule (living or non-living) 

[ ^ ^ * ] crystals (non-living) 

[ 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) leucoplasHdSj colorless; (2) chloroplastids, green; 
and (3) chrotnoplasHds, yellow, orange or red. 

Nucleus. — ^AU 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 



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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 Uvingness. 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'O 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 established 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. 



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CHAPTER in 
ROOTS 

Developm^it 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 setriinal (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 

10 



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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 





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 yoimg 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- 



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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, 



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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 



Pig. 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 



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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, yoimg, 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 
imder favorable soil conditions, that there is a very extensive 



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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 
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 Fig. 5. — Median lengthwise section of 

of members, each with 'J;,'J^^^,,J ^ '°°' ^^ ^^'^"^- ^^^'''' 
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 



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1 6 BOTANY OF CROP PLANTS 

is either naked or surrounded by modified leaves (bud 
scales). TKere 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, hot all roots Uve 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 
(Eickhornia 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 com (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 brace roots (Fig. 56, B). These arise at successive levels 
above the surface, extending obUquely downward. As aerial 
roots, they are unbranched, but they branch profusely when 
they strike the soil. They have the r61e 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 



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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) 
dermatogefiy an outer layer or 
layers; (2) plerome (axis); and (3) 
periblenty between the dermatogen 
and plerome. The dermatogen 
becomes the epidermis y 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. At pr, cortex; m, 
pith; X, stele or central cylin- 
der — all tissue within the peri- 
cycle, inclusive; g, primary 
xylem bundles; &, primary 
phloem bundles. 3, cross- 
section of older portion of 
root; lettered as in A; 6', 
secondary phloem. {After 
Vines.) 



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BOTANY OF CROP PLANTS 



bt. 



r I 



dies are called the xylem, the softer, food- 
conducting bundles, phloem. The central 
portion of the stele is composed of large, 
loosely fitting cells, making up the pUh or 
medulla. 

Side roots arise from the outer edge of 
jl_h ^^ ^^^^^ (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.) 



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ROOTS 



19 



\ 



the plant through root hairs, which are found near the tips of 
the smallest rootlets. In reality, 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-Uke 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 yoimgest 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 seedlings, 
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 seedlings grown in soil is plainly 
evident from the mass of soil particles held 
by the root hairs (Fig. 8). Each root hair 
in its growth flattens out over, and some- 
times partially surrounds, the soil particles 
with which it comes into contact, thereby 
forming a close connection with the water 
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- 
roimding of partigles, explains the presence of the mass of 
soil particles that clings to rootlets in the root-hair zone. 
Root hairs are short-lived, persisting for only a few days or 




Fig. 8.— Wheat 
seedling showing 
soil particles cling- 
ing to root hairs; 
note that the root 
cap is free of root 
hairs. 



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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 Gager.) 

and of almost pure cellulose. A thin layer of protoplasm 
may Kne 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 



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ROOTS 21 

water-soaked soil, the air spaces are filled 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, com, 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'0, 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, 
which 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 Uve 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, imderground perennial stems, such as are possessed 
by quackgrass, Canada thistle, false Solomon's seal, etc., 
may have annual roots. 



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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 life, 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 ^Hilleringy Common cereals invariably produce a num- 
ber of tiUers 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 

32 



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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 imdeveloped stem; it is simply a young 
shoot. In an ordinary shoot, an apple or peach twig^for 
example, the intemodes are considerably elongated. In 
rapidly growing water sprouts, intemodes may be seveml 
inches in length. A bud is a very short, young shoot in 
which the intemodes '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 reality 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) mioced 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 yoimg 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 



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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 reaUty 
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. 



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STEMS 



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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 leaf-scars''' 
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. 10). 
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- 



ferminal leaf -bud 



* flower-buds 
\slipule'Scar 



•..jSklenficels 



: lateral leaf buds 



latent bud^ 



•terminal bud- scar 



, flower- bud-scars 



one 



oldbt 



j/ear^ 



Fig. 10. — Cottonwood twig two years 
old. {After Lon^year.) 



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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 foliage, 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 falling 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 



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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. 



Pig. II. — Section of the lenticel of elder. {After Strashurger.) From A 
Text-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- 



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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 



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STEMS 29 

underground and aerial stems are possessed by such 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" Steins. — 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 diflferent 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 
eflScient 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- 



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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 



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STEMS 



31 



food of the plant is manufactured in the chlorophyll-bear- 
iiig (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 
imdergroimd 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 reality 
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.) 



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32 BOTANY OF CROP PLANTS 

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 kteral 
buds occasionally in the leaf 
axils. Bulbs are vertical 
stems, thus differing from the 
horizontal direction of growth 
of rhizomes. 

4. Corms, — ^A corm 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 

Fig. 14.— Median lengthwise section that their direction of grOWth 

of common onion bulb. j^ 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 



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STEMS 33 

strawberry plant. They are 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 are the 
grape, Virginia creeper, hop, Japan ivy (Psedra tricuspidata) 
and morning glory. The stems of lianas 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 (undiflFerentiated tissue). Although they 



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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 



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 y ground meristem, and 



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STEMS 



35 



O 



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 Btmdle. — 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 cells are somewhat 



Fig. 16. — ^Vascular elements. 
A, annular tracheal tube; B, 
spiral tracheal tube; C, reticu- 
lated tracheal tube; D, pitted 
tracheal tube; £, cross-section 
through plate of sieve tube, 
and adjoining companion cell; 
jF, lengthwise section of sieve 
tube; G, portions of two com- 
panion cells. (£, jF, and G 
after Strasburger.) 



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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 th*e vascular bundle are: tracheal 
tubes, tracheidsj 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. 



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STEMS 37 

Kinds of Tracheal Tubes (Fig. i6). — There are the fol- 
lowing sorts of tracheal tubes: 

1. Annular Tracheal Tubes, — ^Here and there in the tube 
are thickened rings of lignin, 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, 
lignin 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 like a spindle, and they fit closely together 
making up a strong supporting tissue. Tf^heids, 

Wood parenchyma cells are usually thin- walled with bor- 
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; (6) give strength to the 
stem. 

2. Tracheids, — (a) Carry water and solutes; (b) give 
strength to the stem. 

3. Wood Parenchyma. — (a) Store water and foods; (6) and 
also conduct them short distances. 



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38 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 bimdles. 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 lines 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 J and to secondary cortex. Hence, each year, there 
are produced in the dicot stem: 



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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. Camhium 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 Fig. is. — Cross-section of cornstalk 

corn stalk is an excellent ^^^7' «' epidermis; h, cortex and peri- 

cycle; c, ground tissue. {After Stevens.) 

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 



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40 BOTANY OF CROP PLANTS 

from (2) the formation de novo of vascular bundles from 
cells that have retained jtheir 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 19 16) is adjacent to the spring wood of the following 
year (191 7). '^Soft wood" is usually one which grows 
rapidly, and is diffuse 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. 



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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) 
Yoimg stems that contain chlorophyll in their outer layers 
possess the power of manufacturing carbohydrates, just as 
do green leaves. 



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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: 
hldde 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 bimdles 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 



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LEAVES 43 

As examples of the latter, may be mentioned the small 
scale leaves on imderground 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, lilies and most all other 

monocotyledonous plants. In ^^^- 19— a single compound 
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 



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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 
fit 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 



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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 peculiarities, 
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 



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46 BOTANY OF CROP PLANTS 

described above is t3T)ical of dicot leaves growing in situa- 
tions with a moderate water supply. Water leaves are 
thin and have no palisade tissue. Palisade 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 
f ows 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 injury to 
a plant that results from defoliation through any cause, or 
from disease of leaves, or from 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 



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LEAVES 47 

proteins, we see the great importance of a healthy leaf 
development. 

In addition to their important work of carbohydrate 
synthesis, the S3mthesis 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. 



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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- 

. ^..i^^ 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. 

48 



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. 



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FLOWERS 49 

All the flower parts mentioned above, 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 ailfe 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. 
is). 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 prevailing 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 



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so BOTANY or 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 splits 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 saCy at 
this stage consisting of eight nuclei: two synergids, one egg 
nucleus y three antipodals, and two polar nuclei. They occupy 



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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. 



/ei/s 



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 



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54 BOTANY OF CROP PLANTS 

metrical halves by any diameter (Figs. 156 and 162). Such a 
flower is said to be radially symmetrical, or actinomorpkicy 
or regular. Contrast this symmetry with that in such flowers 
as the pea or bean (Fig. 1 7 2^4 ) , in which there is but one plane 
through which the flower can be divided to separate it into 
two synmietrical halves. Such a flower is said to be bi- 
laterally symmetrical^ or zygomorpkic, 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 
gyncecimn 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 gsoicecium). 
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 gyncecium). 

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 imited 
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; 



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FLOWERS 55 



Separate United 

Sepals aposepalous synsepalous 

Petals apopetalous sympetalous 

Stamens polydelphous 



j diadelphous (2 groups) 
\ monodelphous (i group) 



Carpels apocarpous syncarpous 

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 " J^'ce- 
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 imisexual 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 differ with the 
kind of plant. There are three general classes of inflores- 



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$6 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. 



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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. 

(Growing point of shoot, with leaves (bud) . 
Cotyledon or cotyledons. 
Hypocotyl, terminating in the young root or radicle. 

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58 BOTANY OF CROP PLANTS 

Development of the Fruit — The stimulus of fertUization, 
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 pr 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 



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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 swelling 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 Uving an independent Ufe. 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. 



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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 5y5/ma/^V 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 afiinities 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 flow^ers 
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 

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THE CLASSIFICATION AND NAMING OF PLANTS 6 1 

the first natural systems of classifjdng plants (and animals) 
was that of Linnaeus. The first edition of his notable work, 
Systema Naturae, was published in 1735. There follow 
the systems of De Jussieu (1789), De CandoUe (18 19), 
Eichler (1883), Ben tham and Hooker (1826-1883), and Eng- 
ler and Prantl (1890-1896). Two recent systems are those 
of Bessey (1907), and of Schaflfner (1911). 

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 stabiUty 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. 



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62 BOTANY OF CROP PLANTS 

The "thallus plants'' (Thallophytes) include the simplest 
organisms. This group is divided into two large subdivi- 
sions, the Algcs and Fungi. The Algae 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 blight of potato, 
alfalfa leaf spot, apple scab, wilt of cucurbit, etc. 

The *^moss plants" (Bryophytes) include the liverworts, 
peat mosses, black mosses, and common mosses. They are 
a group of comparatively slight 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 GymnospernKB (pines, 
spruces, firs, hemlocks, cedars, junipers and other cone-bear- 
ing plants) and the AngiospermcB (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) 
MonocotyledoneSy in which the seeds have one cotyledon, the 
flower parts are in threes, the leaves are parallel-veined, and 



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THE CLASSIFICATION AND NAMING OP PLANTS 63 

the vascular bundles are scattered throughout the pith 
(examples: cereals, onions, asparagus, lilies); (2) Dicotyle- 
doneSy 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.^., 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 
"{?." 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. 



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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. 

Psilo tales — 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 



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THE CLASSIFICATION AND NAMING OF PLANTS 65 

that this species was first 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-galH (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 crus-galli L. In his revision, Beauvois trans- 
ferred the 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 Ruhus 
vUlosus (northern dewberry). 



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66 BOTANY OF CROP PLANTS 

Descriptnre 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- 
cvmibent Trifolium (clover) is Trifolium repens (repenSy 
creeping); the sweet clover with white flowers is Melilotus 
cdha (albay white); the narrow-leafed crab-apple is Malus 
angustifolia (angustus, narrow— /t?K«w, 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 canadensCy the Canada 
blueberry, the specific name indicates geographical distribu- 
tion. The systematist frequentiy 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 * 
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 conmion 
names. Again, several distinct species often may go by the 
same conmion 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. 



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THE CLASSIFICATION AND NAMING OF PLANTS 67 

Bbntham, G., and Hooker, J. D.: Genera Plantarum. London, 1862-1883. 
Bmtton and Brown : An Illustrated Flora of the Northern States and Canada. 

Scribners, New York, 1913. 
Card, Fred W.: Bush-fruits. The Macmillan Co., 1909. 
CoRBETT, L. C: Garden Farming. Ginn & Co., 1913. 
Coulter, J. M., Barnes, C. R., and Cowles, 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 I*flanzenfaniilien. 
Hunt, T. F.: Forage and Fiber Crops in America. Orange Judd Co., 1908. 
Knuth, Paul.: Handbook of Flower Pollination. Translation by J. R. 

Ainsworth Davis. Oxford, Clarendon Press, 1906. 
Montgomery, E. G.: Productive Farm Crops. Lippincott Co., 1916. 
Percival, John.: Agricultural Botany. Henry Holt & Co., 1905. 
Piper, Charles V.: Forage Plants and Their Culture. The Macmillan Co., 

1914. 
Shepperd, J. H.: Root Systems 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., 191 2. 

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. 

WossroLO, Paul.: Leitfaden der Botanik. Berlin, 191 1. 



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PART II 

CHAPTER IX 
GRAMINEiE (POACEiE), 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 

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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 life 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 sH feet (Fig. 
56), emmer and spelt 33^ feet, and wheat more than 4 feet. 

Roots may break through the sheaths (that part of the 



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GRAMINE^ (pOACEiE), GRASS FAMILY 7 1 



Pig. 25. — Wheat plant showing the general habit of grasses. 



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BOTANY OF 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 
(intertwdes) (Fig. 25) which 
are usually hollow, but some- 
times filled with pith, as in 
corn. When young, the in- 
temodes 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 ability to grow. The yoimgest 
part of each internode is at its base, surrounded by the basal 
swelling 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. A, portion of 
leaf at juncttire of leaf and blade; 
B, stem cut in median lengthwise 
section, x 2H. 



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GRAMINE^ (POACE^), GRASS FAMILY 73 

when its stems are bent oyer 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 amoimt 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 than 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 * *moo ting. " The individual branches are known as * ' tillers' ' 



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BOTANY OF CROP PLANTS 



(Fig. 27), and the entire mass of branches is the "siuol." 
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 kaf 
secondary stem 
'-prtmanj stem 

^^rown roots 



C^'grain remam^ 
'^ I ^5^/mtfry 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- 



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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 
(Phleum pratense) and tall oat grass {Arrhenatherum elatius), 
some of the lower, short intemodes are enlarged into bulb- 
like bodies containing a store of nourishment. 

Rhizome-bearing Grasses. — ^Perennial grasses usually 
have rhizomes or rootstocks, horizontally elongated under- 
groimd stems, which give rise to erect annual stems that 
bear foliage leaves and flowers. These undergroimd 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 



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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 intemodes 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 most rhizomatous 
grasses. Neither is it likely that the former would produce a 



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GRAMINE^ (POACE^), GRASS FAMILY ^^ 

sod that would be as enduring imder 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 ne:^t above or next below, is on the opposite side 
of the stem, i8o° aroxmd 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 y 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 aroimd 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, lilies 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). 



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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 foKage 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 Hordeae, 
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 spikeleL The spikelet is, in fact, the unit of the 



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GRAMINEiE (pOACEiE), GRASS FAMILY 79 

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 imbranched, 
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. UsuaUy, each cuhn bears a 
single spike. In the raceme, each spike- 
let is borne on a short branch of the 
rachis, as in sheep's fescue {Festuca 
ovina). In the panicle, the primary kmmas 

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 tj^es of. inflorescences be- 
sides the spike, raceme and panicle will fig. 28.— Single spike- 

t_ A. *A^ • i? .1 r n • let of common wheat 

be met with m some of the foUowmg (Triticumfiestivum). xa. 
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 tj^ical 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 



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8o 



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 gliunes, 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. 




2d$f*j*n^ 



Iji power i^£lme 



Fig. 29. — Spikelet of common wheat (Triticum aestivum) 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 



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GRAMINEiE (POACE^), GRASS FAMILY 8 1 

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 
{staik) is attached at the base of the anther, but on account 



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 Colean- 
thus, 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-keeledj 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 Streptochceia and Oryza (oc- 
casionally), there are three styles, and only one in Nardus. 
6 



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82 BOTANY OF CROP PLANTS 

The awns 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 cleistogabious 
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, chasitiogamous spikelets and 
cleistogamous spikelets may occur in the same inflorescence. 
According to Koemicke, 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 glimies 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 split open at maturity to allow the seed to escape. The 
pericarp (ovary wall) is firmly attached to the seed coat. 



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GRAMINE^ (POACE^), 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 Uly-like 
plants by a reduction and modification 
of a number of parts of the flower. 
Examination of the floral diagram of a 
typical Hly 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. 
i4, /, bract; ax, axis; 
op, outer perianth; ip, 
inner perianth; s, sta- 
mens; c, tricarpellary 
ovary. J5, shaded struc- 
tures are aborted; le, 
lemma (bract) ; ax, axis; 
p and p', palet (outer 
perianth); I and V, 
lodicides (inner peri- 
anth); 5 and 5', two 
whorls of stamens; c, 
tricarpellary ovary. (J5 
after Schuster.) 



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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-carpeUed, the 
grass pistil is really tri-carpeUary. 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 aU 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 StreptochcBta and BambuscB, 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, sl 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 



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GRAMINEiE (pOACEiE), GRASS FAMILY 85 

structure; the third, outer perianth whorl aborts. In this 
connection it should be noted that the palet of einkorn 
(TrUicum 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 {Cyperaced), 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 
(Juncacece), 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. 



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86 BOTANY OF CROP PLANTS 

References 

Baillon, H.: L' evolution de rinfloresceiice dans Ics Graminees. Bui. 

Soc. Linn. Nord, France, 1894, 11 23-1 128. 
Bruns, E.: Der Grasembryo. Flora, 76: 1-33, 1892. 
Chase, Agnes: Notes on the Cleistogamy of Grasses. Bot. Gaz., 45* i35- 

136, 1908. 
DoELL.: Untersuchungen fiber 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. Sd. Nat. Bot., 9: 1-59, 1899. 
Hackel, E.: tJber das Aufbltthen der Graser. Bot. Ztg., 33: 432, 1880. 

Untersuchungen tiber die Lodiculae der Graser. Engler's Jahrb., i : 336- 

361, 1881. 

The true grasses. Transl. from German by F. L. Scribner and E. A. 

Southworth. Henry Holt & Co., New York, 1890. 

tJber Kleistogamie bei den GrSsem. 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. ScL (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 Spikdet. Science, 

n. s., 23: 789-790, 1906. 
RowLEE, W. W.: The Morphological Significance of the Lodicules of Grasses. 

Bot. Gaz., 25: 199-203, 1898. 
Schuster, Julius: Vber 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: 

2x2-226, 1893 (contains bibliography on development of grain). 



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GRAMINE^ (pOACE^e), GRASS FAMILY 87 
C£R£ALS 

Cereals are those grasses which are grown for their grain. 
Buckwheat is sometimes considered a cereal because its 
fruit (achene) is groimd 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^ 

* 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 spedes, 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 MUlets; 
and the second, Avena, Secale, Triticum and Bordeum, 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, TrUicum and Hordeum, are subdivided on the basis of their inflores- 
cences. Avena has a panicle inflorescence, while Secale, Triticum, and Bor- 
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 whetho: 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, 



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88 BOTANY OF CROP PLANTS 

by examinaUon of this unknown plant, we find now that there are ** three 
spikdets at each jomt of the rachis," it must belong to the genus Hordeum 
(barley). 

The "key" shows many of the characteristics of a group. Consider 
TrUicum (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 hurs 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-Uke, 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 (nee), 
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 
com, etc.) 
Lemma and palet, at least of perfect flower, never thin and papery, 
parchment-Uke or leathery, hard and shiny, very different in color 
and appearance from the glumes (Fig. 83), Chatochloa, Echinochloa, 
Panicum, 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), AvetM (oats). 
Inflorescence a spike. 
One spikelet at each joint of rachis. 

Glumes bristie-like (Fig.*^55), Secale (rye). 
Glumes not bristle-Uke, broad (Fig. 28), TrUicum (wheat). 
Three spikelets at each joint of rachis (Fig 49), Hordeum (barley). 

Key to Small-grain Seedlings^ 

^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. 



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GRAMINE^ (pOACE^e), GRASS FAMILY 89 

• 
Collar without claw-like appendages, Oats (Avena sativa). 
Collar with daw-like appendages which clasp the stem more or less. 
Qaws hairy. 
Sheaths and blades finely pubescent, soft, and velvety, Emmer {Triti- 

cum dicoccum). 
Sheaths and blades not pubescent. 
Collar and claws large, Spelt (Triiicum speUa). 
Collar and claws slender. Wheat {TrUicum astivum). 
Claws not hairy. 
Collar and claws large and prominent. 
Nerves of blades not prominent, upper surface rough. Barley {Hor- 

deum sativum). 
Nerves of blades broad and prominent, smooth on upper surface, 
Polish wheat (TrUicum polonicum). 
Collar and claws slend^. 
Blades and sheaths sparsely hairy. Rye (Secale cereale). 
Blades and sheaths free from hairs, Durum wheat {TrUicum durum) » 

References 

Aaronsohn, a.: Vber die in Pal^stina und Syrien wildwachsend aufgefun- 
denen Getreide-arten. Verhandl. K. K. 2^1. Bot. (resell. Wien., 
59:385-590,1909. 
Contribution d Thistoire des cereales. Bui. Soc. Bot. (France), 1909. 

Attesberg, a.: Die Nachreife des Getreides. Landw. Versuchstat., 67: 
129-143, 1907. 

Carleton, 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: Uber den Ursprung der Stfirke im Getreidekom. 
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. 

Fruwirth, C: Das Bltihen des Getreides. Jahrb. Deut. Landw. Gesell., 
22: 68-75, 1907. 

Fruwirth, W.: Die Ztichtung 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. 
Wber die Entstehung und das Verhalten neuer Getreidevarietaten. 
Archivs ftir Biontologie, 1908. 



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90 BOTANY OF CROP PLANTS 

• 
Kkaus, C: DieLagerung der Getreide. Stuttgart, 1908. 
Knissling, L.: Untersuchungen tiber die Keimung der Getreide. Landw. 

Jahrb. (Bayem), 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 Getreidekom. Berlin, 191 2. 

Hunt, T. F.: The Cereals of America. Orange Judd Co., New York, 1905. 
NowACKi, A.: Anleitung zum Getreidebau, IV. Berlin, 1905. 
RiMPAU, W.: Das BlUhen des Getreides. Landw. Jahrb., 1882 (contains 

the old literature on the blooming of grasses). 
Untersuchimgen tiber 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.: Cber den Entwicklungverlauf beim Getreide. Ein Beitrag 

zur Sortenkenntnis. Landw. Jahrb., 45: 267-324, 1913. 
ScHULz, A.: Die Geschichte der kultivierten Getreide, I. Halle, 1913. 
ScHULz, B.: Wurzelatlas. Darstellung naturlicher Wurzelbilder der Halm- 

frUchte in verschiedenen Stadien der Entwickelung. Berlin, 191 1. 
Seelhorst, v.: Versuche tiber die Moglichkeit einer Bewurzelung und 

Advei^tivtriebbildung an oberirdischen Knoten von Getreidepflanzen. 

Jour. Landw., 1902. 



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CHAPTER X 
TRTTICUM (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 



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92 BOTANY 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 "Aead" 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 



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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. 




4-45 
A.M. 








Fig. 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 9:00 



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94 BOTANY OF CROP PLANTS 

a.m., there is less blooming; this is followed by 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 -.30 
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 usuallyjn several days. 

In northern cold or wet climates, close pollination (auto- 



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TRITICUM 95 

gamy) is the rule in nearly all wheats. Durum wheat, how- 
ever, has the habit of cross-poUination {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-poUination 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 locaUties, such as certain parts of India. 

Artificial Cross-poUination. — 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 
effect cross-fertilization. 

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 fertilization, the embryo begins to develop, the endo- 
sperm to store reserve material, and the seed and fruit walls 
to undergo marked changes. 



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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 pollination. 
About a week later, two other rootlets 
appear above the first pair, and 
Brenchley describes a fifth lateral 
I rootlet, which does not appear until 
quite late. 

Endosperm,— In about a week or ten 
days after fertilization, a definite tissue 
is formed within the embryo sac. This 
is the endosperm. About seven or 
__ . eight days later, the aleurone layer is 

matic section of young marked off, appearing first on the dorsal 
S'e^y?''^^''** ^"^^'"^ ^^^^- 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 pollination. 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: 




o¥ule\ 



mierof^i 



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TRITICUM 97 

1. Outer epidermis — one row of cells. 

2. Parenchyma layer — many 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. Nucellus — 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 
first, 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 persist 
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. 

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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; 
itjs then said to be in the dead-ripe stage. 

Nowacki gives the following analyses of grains of wheat at 
different stages of development: 



Milk-ripe (a) July 9 
Milk-ripe (Jb) July 13 

Yellow-ripe July 20 

Full-ripe July 23 



Water content 
of grain 



Dry substance 

in 100 grains. 

grams 




The maturity of the grain appears to affect its vitality. 
Kedzie has shown that wheat collected in the dough stage 



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TRITICUM 99 

3delded 25 bushels per acre; in the full-ripe stage, 30 bushels 
per acre, and in the dead-ripe, 2& 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 with 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 insuflSicient 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 spik^let 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 environmental 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 



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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; Bt 
grain, embryo side; C, cross-section of grain through the embryo; D, cross- 
section of grain beyond the embryo. 



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 CFig. 35) : 



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TRITICUM lOI 

1. Ovary wall or pericarp y of several cell layers. 

2. Testa, two layers of inner integument. 

3. Nucellus. 

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 lignified. 
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 einkom 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 sKghtly lignified. 

The coloring matter of the grain is found in the inner layer 
of the testa. It is of two kinds, pale yellow and orange 



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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 
Bordeum, that the semi-permeability of the grain coats is 
localized 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 imdeveloped 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 imtil its roots are taking substances 
from the soil, and the yoimg leaves are manufacturing food, 
or, in other words, until the young plant has established its 
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 



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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 



jffjrchy 
endosperm- + — — 

aleurone 



scuiellum- 
coleoptile 




groove 



hndnc 
ifhelium 



V'of 
jx^ulellutn 



hyipocotyl — 
epibmt — 

'^ rooi 

cdeorhiza 



^ siem 



Fig. 36.- 



-Part of a median lengthwise section of a grain of wheat; much 
enlarged. (After Strasburger.) 



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 amoimt. 
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 formed in 
addition to the two pairs usually described. These»rootlets 
are surrounded by the root sheath or coleorhiza. A very short 



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I04 BOTANY OF CROP PLANTS 

stem, the hypocotyl, is between the primary root and the 
growmg 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 surroimding 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 epiblast. 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 groimd 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 
monocptyledonous. 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 aU 
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 



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TRITICUM 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 cent., 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 



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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 y 3 to 4 per cent. 

3. Starchy ox floury endosperm j 82 to 86 per cent. 

4. Embryo or germ, about 6 per cent. 

"Hard" and "Soft" Wheats,— A "hard '' wheat is one with 
a homy 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 difl&culties 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 



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TRITICUM 107 

and Bluestem. Turkey and Kharkov are the chief hard 
winter wheats, and Kubanka the most important durum 
wheat. On accoimt 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 



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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 groimd 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 Flotir. — 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 794-1851), 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 ^^straighV' 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 



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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. Gtermina- 
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 40°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 yoimg 
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 groimd. 

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 dr)aiess, 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: 



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BOTANY OF CROP PLANTS 
Repeated Germination 



Kind of seed 


Per cent, germinated 


I8t 


2d 


3d 


4th 


sth 


6th 


Schumacher wheat 

Clawson wheat 

Buckwheat 


lOO 
lOO 
lOO 


lOO 
lOO 
lOO 


90 

97 
100 


87 
98 

98 


67 
84 

65 


8 
38 
39 







Classification of the Types of Wheat— Hackel divides the 
genus Trittcum into two sections, Aegilops and SUopyros. 
In the first, the glumes are flat or rounded on the ba:ck; 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). 



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TRITICUM III 

Spikdets more than two-flowered, two or more fertUe; terminal spikelet 
developed; lateral teeth 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, 
spdta (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, homy, long. T. durum (durum 
wheat). 
Spike short, crowded, long^vate; glumes usually pubescent; grain 
short, blunt and softer than that of T, durum, T. turgidum 
(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 small, short. T, 
compactum (club wheat). 
Spikes longer than 2 inches, open; sides usually parallel or nearly 
so. T. astivum (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, cestivum, 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). 



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112 BOTANY or CROP PLANTS 

Beyerinck has succeeded in producing crosses of einkom 
with dtcoccum, none of which were fertile, however. Aaron- 
sohn says that T. polonicum hybridizes with the other species, 
T. (Bstivum and T. monococcum, but the oflFspring are not 
fertile. 

T. monococcum (einkom) 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- 
nicuxn) ; 2, club wheat (T. compactum) ; 3, common bread wheat (T. aestivum) ; 
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. 
TrUicum agUopoides is considered to be the wild form of our cultivated ein- 
korn. This wild species is divided into the two subspecies: T, thaoudar and 
T. boeoHcum, In the first, only the lower flower is fertile, as a rule, but both 
bear awns, while in hoeoticum 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 einkom. T, (BgUopoides differs from cultivated forms of 
einkorn in that its spikes are more fragile, and the grains smaller and lighter 
in color. 



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TRITICUM 113 

T, polonicum (Polish wheat) is not a native of Poland, but occurs in Italy 
and Abyssinia in Africa. It is cultivated to some extent in this country. 

T. spdta (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 Westfern 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 they are better yielders than (Bstivum wheats. 



Pig. 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. aestivum) ; 5, club wheat (T. compactum) ; 6, dtirum wheat (T. durum) ; 7, 
Poulard wheat (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, 
r. 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 S toner, 
Miracle, Eldorado, Jerusalem, Many-headed, Many-spiked, Wild Goose, etc. 
8 



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114 BOTANY OF CROP PLANTS 

T, compactum (club wheat) varieties are said to be adapted to the 
Pacific Codst 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 dub-shaped. The 
joints of the rachis are very short, so that the spikelets are crowded and often 
stand outright. 

r. (Bstivum (common wheat). — ^The bread wheats of the world are largely 
varieties of (Bstivum, 

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 GaUlee to the north 
of Lake Tiberias, he found this wild emmer again, and, on 
Mount Hermon near the village of Amy, 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 einkom, 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 chmates. 



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TRITICUM IIS 



Fig. 40. — Wild emmer of Palestine (Triticum dicoccum dicoccoides) , grown 
in experimental plat at Bard, California. {Cook, U. S. DepL of Agr.) 



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Il6 BOTANY OF CROP PLANTS 

where cold or wet weather prevents flower opening. In 
India, it has been observed that cross-pollination in wheat is 
more frequent than in northern climates. 

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 
l^ ?! ^^^^ emmer given by Schulz, is shown in the following: 
cum 'di^ccoideT)" '* Einkorn series, of which T, mgUopoides is the 
X 2M. prototype. 

2. Emmer series, of which T, dicoccoides is the stem 
. form. From this have come dicoccum, durum, turgidum, and polonicum, 

3. Spelt series, of which the stem form is unknown. From this have come 
spelta, compactum, asUvum, and capitatum. 

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, 



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TRITICUM 117 

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 imits of water absorbed by the plant in the 
production of a imit of dry matter. The following data are 
taken from Briggs and Shantz: 

Water-requieement Determinations at Akron, Colorado, 1911, 191 2, 
AND 1913, Based on the Production of Dry Matter 

Plant Mean of genus 

Proso 293 

Millet 310 

Sorghum 322 

Com 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 



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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 ^^ semoUna.^^ 




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 



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TRITICUM 



119 



are also made from semolina and water, but dies of different 
form are used, and dr3dng 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 
coimtries of the world are shown graphically in Fig. 42. 
The following table gives the wheat production in the United 
States for 1915. 

Wheat Production in the United States, 191 5 



state 


Acres 


Bushels 


Total value 
dollars 


North Dakota 


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 


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 


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 


Minnesota 


Nebraska 


South Dakota 

niinnia 


Washington 

Indiana 


Ohio 


All other States 


United States 


59,898,000 


1,011,505,000 


930,302,000 



References 
Aakonsohn, a., and Schweinfurth, G.: Die Aufl&ndung des wilden Em- 
mers (Triticum dicoccum) in Nord Palastina. Altneuland Monatsschr. 
filr die wirtschaftliche Erschliessung Palastinas, Berlin, Nos. 7-8, 213- 
220, 1906. 



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TRITICUM 121 

Aaronsohn, Aaron: Agricultural and Botanical Exploration in Palestine: 

Wild Prototypes of Wheat and Other Cereals in Palestine. U. S. Dept. 

Agr. Bur. Plant Ind. Bull. i8o: 36-52, rpio. 
Beijerinck, M. W.: tJber den Weizenbastard Triticum monococcum 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: 117-139, 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 Palestme. 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 S)rstematik des cultivierten Weizens. Landw. 

Versuchsstat., 45: 37-i3S» 1894. 
Fruwirth, C: Das Bluhen von Weizen und Hafer. Deut. Landw. Presse, 

32: 737-739, 747-748, 1905. 
Hays, Willet M., and Boss, Andrew: Some Botanical Characteristics of 

Wheat. 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, 19 10. 
MoBius, F.: Untersuchungen tiber 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. Washington 

Pub. 84: 1-119, 1907. 
ScHULZ, August: Abstammung und Heimat des Weizens. 39 Jahrsber. 

Westfal. Prov. Ver. Wiss. u. Kunst (zu Mtinster) ftir 1910-1911, S. 

147-152, 1911. 

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.; Microchemical Studies in the Progressive Develop- 
ment of the Wheat Plant. Wash. Agr. Exp. Sta. Bull. 139; 1-20, 1917. 



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122 BOTANY OF CROP PLANTS 

Die Abstammung des Einkorns (T. monococcum L.). Mht. Naturf. 

Gesell. Halle, 2: 12-16, 1913. 

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. 



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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 foimd clinging 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 yoimg roots; hence, the 
root crown formed considerably above the seed, the lower root 
stem remaining rudimentary and the little 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 

"3 



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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 primary branch, 



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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 sativa), 




Fig. 45. — At 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 



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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 Sai flower 
paleK 




I 



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 from 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, 



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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 are 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 :oo 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 surroimded by 
the lemma and palet, except in *' naked oats." The lemma 
and palet form the '^hull" (Fig. 47). The quaUty 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. 



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128 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 



Fig. 47. — A, mature grain of wild oats (Avena fatua); 5, mature grain of 
cultivated panicle oats (Avena sativa) ; C, grain of same with "hull*' removed; 
D, cross-section of grain with the "hull." A, B a.ndC, 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. 



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AVENA 129 

There are marked dijBferences 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 dijBferent 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. 
9 



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130 BOTANY OF CROP PLANTS 

Classification of Oats. — The common oat varieties in the 
United States fall into three species: Avena saliva, A, 
orienkUiSy 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 orienlalis (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 huU-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, byzan- 
lina (Mediterranean oats) and A . abyssinica (Abyssinian oats) . 

Avena fatua ("wild oats")* — The so-called "wild oat" is 
often foimd 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 



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AVENA 131 

latter by the long reddish-brown hairs at the base of the 
lemma and on the rachilla. 

In cidtrvated sorts^ there appears occaaonally 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, 
sativa, A. orientaliSj 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, barbata, a 
species growing wild in the Mediterranean region, Persia, 
Mesopotamia, west to Atlantic Europe and Great Britain. 
A, abyssinica is originated from A, wiestiiy 2l species in- 
digenous to North Africa and Arabia. A, byzantina has 
come from A, steriliSy 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 sterUis 
("sterile" oats), beginning with those that are small and 
useless and ending with the forms now cultivated there. 
Algerian oat (-4. algeriensis) is the common cultivated variety 
of the sterile oat. 

All the forms of oats derived from A, fatua 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, sterilis, 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 cUmate, such as is found in the region north 



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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 Production of Oats. — As is the case with wheat and 
com, the United States also leads all other coimtries in the 
production of oats. Russia is a close second. Iowa, 
IlUnois and Minnesota were the leading States in 191 5. 

Leading Countries in the Production of Oats, Showing Acreage and 
Production, 191 5 



Countries 



United States 

Russia, European 

Germany 

Canada 

France 

Austria-Hungary 

United Kingdom 

Sweden 

Argentina 

* No official statistics, 



Acres 



Bushels 



40,780,000 
44,787,000 

11,365,000 
9,051,000 

4,149,000 

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 



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1 



AVENA 133 

The Production or Oats in the United States, 191 5 



States 


Acres 


T».,„t,«i» Total value, 
^^s^^^s dollars 


Iowa 


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 


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 


63,360,000 
68,402,000 


Illinois 


Minnesota 


43,000,000 
35,991,000 
26,460,000 
20,286,000 
21,824,000 


Wisconsin 


North Dakota 

South Dakota 

Nebraska 


Ohio. . . 


24,841,000 
22,277,000 


Indiana 


Michigan.. . . 


22,490,000 
206,638,000 


All other States 


United States | 40,780,000 


1,540,362,000 555,569,000 

1 



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. Fuhling'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. 
Criddle, N. : The So-called White Wild Oats and What They Are. Ottawa 

Nat., 23: 127, 1909. 
Wild Oats and False Wild Oats; Their Nature and Distinctive Charac- 
ters. Canada Dept. Agr. Bull. 7: i-ii, 191 2. 
Denaiffe and Sirodot: L'avoine, etc. Paris, 1902, 210 figures, pp. 848. 
Fruwith, C: Die Haferrispe bei der Beurteilung der Sorten und in der 

Ztichtung. Fuhling's Landw. Ztg., S. 289, 1907. 
Haselhoff, E.: Vergleichende Untersuchungen deutscher und amerikanis- 

cher Haferkomer. Landw. Vers. Stat., 65: 339-349, 1907. 



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134 BOTANY OF CROP PLANTS 

Haussknecht, E.: tJber die Abstammung des Saathafers. Mitt. Thiiring. 

Bot. Ver. N. F. Heft, 2: 45-49, 1892. 
Raum, H.: Zur Systematisierung der Hafersorten. Ftihling's Landw. Ztg., 

58: 496-501, 1909. 
RmPAUy W.: Die genetische Entwicklung der verschiedenen Formen unserer 

Saatgerste. Landw. Jahrb., 21: 699-702, 1892. 
ScHULz, A.: Die Geschichte des Saathafers I und II. Jahrsber. WestfaL 

Prov. Vers. Wiss. W. Kunst. Munster., 41: 204-217, 1913. 
Abstammung nnd Heimat des Saathafers. Mitt. Thuring. Bot. Ver. N. 

F. Weimar., 31: 6-11, 1914. 
Tannert, Paul: Entwickelung und Bau von Bliite und Frucht von Avena 

sativa L. Inaug. Diss. Zurich, 1905. 
Thellung, a.: tJber die Abstammung, den systematischen Wert und die 

Kulturgeschichte der Saathafer-Arten (Avena sativae Coss.) Vrtljschr. 

Naturf. Gesell. Zurich, 56:293-350, 191 1. 
Trabut, L. : Origin of Cultivated Oats. (Translation) Jour. Hered., 5 : 74-85, 

1915. 
Contribution a Tetude de I'origine des avoines cultivees. Compt. Rend., 

149: 227-229, 1909. 
ViEKHAPPER, 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). Ftihling's Landw. Ztg., 369-384, 191 2 



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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. disHchon), 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 su^ested 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 abimdantly 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- 



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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. 



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 



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HORDEUM 137 

no apical spikelet in barley. The groups of spikelets are 
arranged alternately on the rachis. 

Spikelet and Flower. — Each spikelet is one-flowered. The 
glumes are narrow and awn-Uke, 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. 



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 



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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. The styles are short, and the two lodicules are 

conspicuous and vary in the 
different types. 

Opening of Flower and 
PbHioatLon. — ^The blooming 
of a spike begins dightly 
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-rowed 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 




Fig. 51. — A, barley grain with the 
"hull;" B, with "hull" removed; C, 
grain in cross-section. 



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HORDEUM 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 nile, 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. 



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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. Pericarps 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 
thejgrain. 



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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 
Hordeum. 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-Kke 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 compoimd 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 compoimd 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 effect 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 



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142 BOTANY OF 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 abiUty 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 eflSciency 
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 



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HORDEUM 



143 



grows under the lemma and palet to the anterior end of the 
grain and there becomes free. The coleoptile then opens 










^> 



# 



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 foliage leaf appears. In the germination of 
barley, the young leaves become twisted. This is character- 



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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 classiJ&cation of the cultivated barleys. 
There are at least two distinct species: Hordeum vulgare, in- 
cluding the six-rowed barleys, and Hordeum disHchon, 
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 millimeters 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 tj^es 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 



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HORDEUM 145 

overlapping laterals also forming two rows. Furthermore, 
in four-rowed barley, the rachis intemodes 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 raCchis, 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 glimies 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 s)mimet- 
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: 



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146 BOTANY OF CROP PLANTS 

I. Hordeum distichon zeocriton (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). 



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HORDEUM 



147 



3. Hordeum distichon erectum (erect-eared 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 oflF (Fig. 54). Rachis joints are 2.8 to 3.5 millimeters 



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148 BOTANY OF CROP PLANTS 

long. The rachiUa 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 nutans first arose 
from the wild form. From this came erectunij by a shorten- 
ing of the rachis joints. From erectum, came zeocriton 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 trifurcatum. 

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. 



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HORDEUM 149 

Barley stands between oats and wheat in its water 
requirement. 

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 flour 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 forty- 
eight hours in water, and then spread out on the malting 
floor. The temperature of the air in the malting room is 
between 50 and 6o°F. Germination is not allowed to pro- 



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I50 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 
191 5, 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. 



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HORDEUM 



151 



Acreage, Production and Farm Value of Barley in Various 
States, 191 5 



States 


Acres 


Bushels 


Farm value, Dec. 
I, dollars 


North Dakota 

Minnesota 


1,400,000 

1,350,000 

1,360,000 

750,000 

656,000 

353,000 

270,000 

1,256,000 


44,800,000 
41,175,000 
39,440,000 
24,000,000 
23,288,000 
10,943,000 
8,370,000 
44,993,000 


19,712,000 
20,176,000 
24,453,<300 
11,040,000 
13,041,000 
5,362,000 
3,515,000 
25,200,000 


California 


South Dakota 

Wisconsin 


Iowa 


Kansas 

All Other States 


United States 


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 zweizeiligen Gerste-Hordeum 

distichum-am Korne. Inaug. Diss. Univ. Jena, 1906. 
Das Gernstenkorn im Bilde. Stuttgart, 1908. 
Brown, H. T., and Escombe, F.: On the Depletion of the Endosperm of 

Hordeum Vulgare during Germination. Proc. Roy. Soc. (London), 

63:3-25, 1898. 
Fruwirth, C. : Das Bluhen der Gerste. Fuhling'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 uber das Bluhen der Gerste (Schwedisch). 

Bot. Notiser., 1905. 
Hummel, A.: Die botanischen Unterscheidungsmerkmale bei zweizeiliger 

Gerste. lUus. Landw. Ztg., 830-839, 1909. 
JOHANNSEN, W.: Entwickeluug und Konstitution des Endosperms der 

Gerste. Ztschr. Gesam. Brauw., 1905. 
Kraus, C: Die Gliederung des Gersten- und Haferhalmes und deren Bezie- 

hungen zu den Fruchtstanden. Beiheft I der Naturwis. Ztsch. fur 

Land- und Forstwirthschaft. Munchen, 1905. 



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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 und brautechnischen Eigen- 

schaften und ihre Anbau. Berlin, 1913. 
RiicPAU, 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 I-II. Mott. Naturf. 

Gesell. Halle, i: 18-27, 191 2. 
TscHERMAK, E.! Die Bluh- und Fruchtbarkeitsverhaltnisse bei Roggen und 

Gerste und das Auftreten von Mutterkorn. Fuhling's Landw. Ztg., 

S. 194, 1906. 
Voss, A.: Versuch einer neuen Systematik der Saatgerste. Jour. Landw., 

33: 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. 



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CHAPTER XIII 
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 diflfer- 
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 
S 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 



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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 two cereals cannot be self-fertilized 
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,X2H; B and C, 
X5. 

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 9 : 00 or 1 1 : 00 a.m. Then 
blooming decreases throughout the afternoon, becoming 



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SECALE CEREALE 155 

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 place 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 Secale anatolicum, one of the subspecies of S. 
montanum. This stem form differs from S. cereale in the 
fragile rachis, the smaller, narrower fruit, and perennial 
rootstock. I 

Enviromnental Relations. — Rye is adapted to colder and 



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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 1915; 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. 
Rqipau, 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 Miinster) 

fiir 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 Bluhen beim Roggen. 

Ber. Deut. Bot. Gesell., 22:445-449, 1904. 
Das Bluhen 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.: Uber die Stammpflanze des gemeinen Roggens, Secale 

cereale. Verhandl. Bot. Ver. Brand., 32:32-34, 1890. 



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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 
oflf 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 (&) 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 

IS7 



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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 



ground line 




\-i 



L 

I 
I 

h 



U-1 



a 



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. 



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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 that an important 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 J^ 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 
imderground 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 r61e of absorption, then, 
as well as anchorage. 



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l6o BOTANY OF CROP PLANTS 

Stem. — Com 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 ^^ sucker s^^ 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 



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ZEA l6l 

reqiiirement of the plant is low as compared with oats, 
clover, or alfalfa. It has been computed that an average 
acre of well-adapted com, grown at the Nebraska Agricul- 



PiG. 57. — Pistillate and staminate inflorescences of corn (Zea mays). 

tural Experiment Station, has 4 acres of leaf space, coimting 
both sides. 
Inflorescence. — Ordinarily, com is monoecious, that is. 



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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 
"/a55e/." 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 
Fig. 58.— A palet is larger than the lemma, while in the 

the staminate in- lowcr flower, the lemma is larger than the 

florescence of ^^^^^ 
corn (Zea mays). * 

Pistillate Inflorescence ("ear'') General 
Characteristics. — The ear (Fig. 61) is borne on a short 

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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 



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." 



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164 



BOTANY OF CROP PLANTS 



What Is the ^'Ear'^ Morphologically? — There are two 
theories as to the morphology of the ear of com. 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; At dorsal anther. 
P, rudimentary pistil; J, 
joint of rachilla. {After 
Weatherwax.) 



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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 (Zea mays). Young pistillate inflorescence (" ear"), showing 
the long styles ("silks"). 

(c) Lemma and palet of upper flower become reduced 
while the lower flower becomes abortive, 
(i) Sessile flower becomes pistillate. 
{e) Both flowers become pistillate. 



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1 66 BOTANY O^ CROP PLANTS 

Recently East arid H^y^s have expressed an opinion very 
similar to that of Montgomery. Quoting from them, "The 
ear of maize, then, is a riieristic 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-like structure, 



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 fertilize the flowers on the lower branches. At the same 
time, the lateral branches came to produce only pistillate 
flowers, their position not beiug favorable as pollen producers, 
while, on the contrary, they were favorably placed to receive 
pollen. This differentiation 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 



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ZEA 



167 



flowers, the lower one of which is abortive^ (Figs. 62 and 63). 
The paiet 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 com, X 25. Sti, base of stigma; Sty, style; E, outline of embryo sac; 
L, lemma; Pa, palet; St, stamen of aborted flower; Sc, stylar canal; Ov, func- 
tional ovule; Gl glume; Sta, rudimentary stamen; P, pistil of aborted flower; 
/, joint of rachilla. (After Weatherwax.) 



by two glumes that are shorter than the ovary, very broad 
and fleshy at the base, thin membranous above and fringed 

* 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. 



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l68 BOTANY OF CROP PLANTS 

on the edges. The lemma and palet of the fertile flower are 
short, broad and membranous. In pod com, glumes, lemma, 
and palet attain a considerable size and enclose the grain. 
The single ovary bears one long style, the com **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 
com 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 tme to 
t3rpe. 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 



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ZEA 169 

were of unusual appearance, being 5 feet high, with short 
intemodes and broad leaves. 

Opening of the Flowers, and Pollination. — Cross-pollina- 
tion, consequently cross-fertilization, is the rule in com 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 
the 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 little at a time. In 
investigating a number (59) of varieties of com as to the 
time elapsing between the appearance of anthers and appear- 
ance of first silks, Gemert 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- 



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170 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 com 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 Lea;ming 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 com varies from 0.08 to o.i millimeter. 
They are rather ellipsoidal in shape. Com pollen soon 
shrivels after being shed, but its germinating power is not 



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ZEA 171 

destroyed by this. However, pollen does not remain viable 
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 pollinate 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, 
fertilization is not prevented when tips of silks are 
cut off. 

Fertilization, and Development of the Grain.— Just prior 
to fertilization, the ovary of com 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 (raghilla) about 2.5 millimeters 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 fertilization, 
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 



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172 BOTANY or CROP PLANTS 

the base of the style, on the posterior side." This is probably 
the "stylar. canal" described by Poindexter. 

The outer and inner integ^ments 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 Com.— Xenia is the term applied to the phe- 
nomenon in which some character of the miale appears at 
once in the seed. For exapaple, in crossing a strain of com 
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, 



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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 
diflFerences 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 9ther 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 y^e 
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 com 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 com 



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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 Com. — If our ordinary 
field strains of com 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 kemels on an ear 




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 quaUties. Furthermore, artificial 
self-fertilization 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 Com. — The mature grain of corn 
varies considerably in shape (Fig. 64). In most varieties. 



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ZEA 175 

it is flattened 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 foimd 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 y 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 . o to 14 . o 

Horny endosperm 45 . o 

Starchy endosperm 25 .0 



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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 homy 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 




Pig. 65. — ^Variation in the shape of corn grains. Which is the best propor- 
tioned kernel? Why? {After Mich. Agr. Exp. Sta. 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 com kernels, the homy 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. 



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ZEA 177 

Embryo, — In the nonnal flower, 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. 

Grains rounded, with central hilum; small grains globular or angular, 
Wheat. 

Grains large, of various shapes, with excentric 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., 



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178 BOTANY or CROP PLANTS 

maximum 114.8°?., 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 s8.s°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. ColUns 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 muys 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 saccharata, sweet corn. 

7. Zea amylea-saccharata, starchy sweet corn. 

*The specific name "mays" is omitted, for convenience, from the 
following. 



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ZEA 179 

Gemert describes a type of corn with branching ears and 
highly branching tassels, which he considers as a distinct 
subspecies and for which he suggests the name Zea 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 teosinte. 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 hirta is a 
hairy, South American corn. Zea mays curagua is a form 
with serrate leaves. 



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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 
type, 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 homy 
(corneous) endosperm; kernels and ears small, Zea everta (pop corn). 
Grains without popping properties. 
No corneous endosperm, hence grains are soft; shaped like flint com; 
no indentation; the mununy corns of Peru, Mexico, and southern 
United States probably belong to this group, Zea amylacea (soft 
com). 
Corneous endosperm present. 
Grains more or less wrinkled or shrivelled; kernels homy and trans- 
lucent in appearance. 
Grains homy throughout, Zea saccharata (sweet com). 
Grains with upper half homy and translucent, the lower half 
starchy, Zea amylea-saccharata (starchy sweet com). 
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 indentata (dent com). 
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 com). 

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 by 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 



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ZEA l8l 

small, angular, and does not have the appearance of the 
typical corn starch granule. Sweet corns may be regarded 



Fig. 67. — Teosinte (Euchlaena mexicana). {After Collins and Kempion 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 



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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 (Euchlcena 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 tunicata). 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. 



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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 95th meridian, hot winds 
sometimes prove fatal to corn. These winds are particularly 
harmful during the critical periods of 'Hasseling'' 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. 



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l84 BOTANY OF CROP PLANTS 

Corn 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 vidcanized 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 



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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 J and are made from starch. Starch is heated to a 
temperature varying from 170 to 270^0. 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. 



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1 86 BOTANY OF CROP PLANTS 

leaves, and ears — and in this form is fed to stock. Com 
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 Ughtness 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 Com. — In 1914, the United States produced 
2,672,804,000 bushels of com, which was over 70 per cent, 
of total production for the world. The coimtry ranking 



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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 Illinois, 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 
1915 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 

BoHUTiNSKY, GusTAv: Entwicklungsabwcichungen beim Mais. Ber. Deut. 

Bot. Gesell., 32: 179-188, 1914. 
Bowman, 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: 34^395, 1909- 
Incomplete Dichogamy in Zea Mays. Jour. Bot. (London), 47:180-182, 

1909. 
Maize, Its History, Cultivation, Handling, and Uses. Longmans, Green & 

Co., 1914. 
Collins, G. N.: A New Type of Indian Corn from China. U. S. Dept. Agr. 

Bur. Plant Ind. Bui. 161: 1-25, 1909. 



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ZEA 189 

Apogamy in the Maize Plant. U. S. Nat. Mus. Contrib. Nat. Herbarium, 

12:453-455,1909. 
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, i : 293-302, 19 14. 
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, 191 2. 
A Chronicle of the Tribe of Com. 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 Com Pollination, I. Proc. Ind. Acad. 
Sci., 1908. 
Report of Work in Com 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, 191 1. 
A New Subspecies of Zea Mays. Am. Nat., 47: 616-622, 1912. 
Guignard, L.: La double f6condation 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, 190T. 
Hopkins, C. G., Smith, L. H., and East, E. M.: The Stmcture of the Corn 
Kernel and the Composition of its Different Parts. 111. Agr. Exp. Sta. 
Bull. 87: 77-112, 1903. 
Hus, H., and Murdock, A. W.: Inheritance of Fasciation in Zea Mays. 

Plant World, 14: 8S-96, 191 1. 
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-fertilizaticn of Varieties of Corn. 2d Ann. Rept. 
Kans. Agr. Exp. Sta., 346-353, 1890. 



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IQO 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, 191 1. 
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: 1 15-123, 1905. 
Shoesmith, V. M.: The Study of Corn. Kans. Agr. Exp. Sta. Bull. 139: 
223-249, 1906. 
The Study of Corn. Orange Judd Co., 19 10. 
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. Agr. Office Expt. Stats. Bull. 5;: 1-103, 
1899. 
Weather wax, Paul: Morphology of the Flowers of Zea Mays. Bull. 

Torrey Bot. Club, 43: 127-144, 19 16. 
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. 



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CHAPTER XV 
ANDROPOGON SORGHUM (Sorghums^ 

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 milo, kowliang, shallu, durra, broom corn, and kafir. 

191 



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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. 



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 



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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 ofskrik ji 





1^ ^lume 



Itxt glume 



j Jertile flower- 

FiG. 71. — spikelet of sorghum (Andropogon sorghum) dissected. 
X 10, all others X 5- 



Lodicule 



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. 
13 



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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 amoimt of blooming during 
the day. The stigmas may protrude to a sUght extent first. 
(Fig. 7 2) . 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- 



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> 



ANDROPOGON SORGHUM 



195 



shedding anthers may be m contact at time of opening, and 
since the stigma is receptive at this time, some self-pollination 
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 



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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. 

Emit. — 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 maiA di- 
virfons: (i) saccharine or sweet sorghimis, 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 com group, in which the heads are 
loose and spreading. Frequently the heads are on recurved 
stems, called "goose necks.'' 



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ANDROPOGON SORGHUM 197 

Key to the Principal Groups of Sorghum^ 

Pith juicy. 
Juice abundant and very 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 awned. 
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 Com. 
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, Shallu. 
Panicle oval or obovate, the branches spreading; glumes at maturity 
appressed, not involute; seeds white, brown, or reddish, KowUang. 
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, Kowliang. 
Spikelets broadly obovate, 4.5 to 6 millimeters wide. 
Glumes gray or greenish, not wrinkled; densely pubescent; lemmas 

awned or awnless; seeds strongly flattened, Durra. 
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 halepensis 
(Johnson grass) . This species is native to tropical and sub- 
tropical parts of the Old World. The view is now quite 

1 Taken from Ball. 



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198 



BOTANY OF CROP PLANTS 






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ANDROPOGON SORGHUM 199 

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 dififer from corn, for corn is unable 
to remain in a dormant state for a 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. 



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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 dwarf. 
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) lo 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 
directiy to the broom factory. The "straws" of a broom 
are the rachises of the sorghimi 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, 19 10. 
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: 

i-36» 1911. 
The Importance and Improvement of the Grain Sorghums. U. S. Dept. 

Agr. Bur. Plant Ind. Bull. 203: 1-45, 1911. 
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: 11 5-1 26, 1885. 
Piper, C. V.: The Prototype of the Cultivated Sorghums. Jour. Am. Soc. 

Agron., 7: 109-117, 191 5. 



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^ 



ANDROPOGON SORGHUM 20I 

Hartley, Charles 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. Agr. 

Farmers' Bull. 288: 1-28, 1907. 



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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 }4 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 M 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 fiye-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 

202 



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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-poUi- 



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204 



BOTANY OF CROP PLANTS 



"-r-F-few^n7tf 



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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 paraflln-Uke 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. 



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N 



ORYZA SATIVA 20S 

When it is cooked, there is formed a mass the particles of 
which stick closely together; the single grains do not renpiain 
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 lo 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 poUshing 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. 



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2o6 BOTANY OF CROP PLANTS 

Beriberi. — ^Thb 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-kemeled rice). 

(b) glutinosa (glutinous rice). 

American varieties are comparatively few in number. 
Three main types are grown: Honduras, Carolina 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 



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ORYZA SATIVA 207 

aquatica), and wild rice {Zizania miliacea). Both are tall 
aquatic grasses belonging to the same tribe (Oryzeae) 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 1916, 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 milling 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. 



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2o8 



BOTANY OF CROP PLANTS 



Environmental Relations. — Rice has a cKmatic range simi- 
lar to that of cotton; it is seldom raised north of that region 
in which the average summer (June, July, August) tempera- 




te «i 
1 1 









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 



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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 

AKEinNE, M.: On the Flowers and Flowering of O. sativa. Agric. Gaz. 
N6gy6-Sekai, 1910-11. 

Graham, R. J. D. : 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, Bot. 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, 1912. 
14 



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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 purposes and in a number of Asiatic and 
African countries for himian food as well. 

Most of these millets belong to the four genera Chcetochloa, 
Echinochloa, Panicum, and Pennisetum, of the tribe Paniceae. 
Ragi or finger millet {Eleusine coracana) belongs to the tribe 
Chlorideae. 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. crusgalli (common barnyard grass). 
Awns short; spikelets brown, E, frumetUacea (Japanese barnyard 
millet). 
Inflorescence a drooping panicle; empty glumes not awned, Panicum 
miliaceum (proso or broom-corn millet). 

'After Frear. 210 



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MILLET 211 

Inflorescence spicate; involucre of bristles below each spikelet. 

Grain enclosed in lemma and palet (the hull) at maturity; spike loose, 
Ch(Btochloa (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, Pennisetum 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 tipper nodes either smooth or short-hairy. 

Leaf. — The leaf sheaths aire 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.— rThis 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 glimie 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, 



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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. 

PoUination. — 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 hy 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 



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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 
palet. 

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 nuUet, 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- 
ceum). X 2. 



Stem. — The plants are erect, some- 
times decumbent at the base, and 
often reach a height of 3 to $}4 f^et. 
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 papillae. The ligule is short, 
thick, and fimbriated, and the auricles are lacking. The leaf 



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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. 



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MILLET 215 

Spikelet and Flower. — The spikelets are oval in shape and 
4}4 to s 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. 

PoUination. — 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 effusum. — Panicle broad, the 
branches spreading to all sides. 

2. Panicum miliaceum contractum, — 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 



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BOTANY OF CROP PLANTS 



known. The plant has been cultivated in Europe and 
Asia from the earliest times. 

CHJETOCHLOA ITALICA (FoxtaQ MiUets) 
' 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 3^ 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. 



mm 
ieni 
ower 



fi 



llume 
ties 



Fig. 82. — Spikelet of foxtail millet 
(Chaetochloa italica). X 15. 



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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 



^lume 




fertile Jk 



mfer 



Zod ^/um^ 



Fig. 83. — Dissected spikelet of common millet (Chaetochloa 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. 

PoUination. — 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 23^ milli- 
meters long and i3^ to i3^ 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 



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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. 

Types and Varieties of Foxtail Millet. — Koernicke rec- 
ognizes two main groups of cultivated millets belonging to 
the species Chcetochloa italica: 




Fig. 84. — A, grain of foxtail millet (Chaetochloa 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, Grolden Wonder millet, and Siberian millet. 



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MILLET 219 

2. ChcBtoMoa 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 Types 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 Millet. 
Heads large, more or less open; seeds more or less bunched. 
Heads long, slender, very open, lax, drooping; seed groups very distinct, 

Aino 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 Chcetochloa viridis, the green foxtail. It differs 
from the cultivated forms in that its fruit falls from the 
inflorescence when mature. ChcBtochloa 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^ to 
2 feet long, J^ 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 

^ After Frear. 



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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 FRITMENTACEA (Japanese Barnyard Millet) 

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 ''billion- 
dollar grass" in the United States. It probably originated 
from common barnyard millet {E. crusgalli). 

Enviromnental 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. 



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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 
proso group. The latter is most frequently grown for the 
grain. 

R^erences 

Ball, Carleton R.: Pearl millet (Pennisetum spicatum). U. S. Dept. Agr. 
Farmers* Bull. i68: 1-16, 1903. 



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CHAPTER XVIII 

PHLEUM PRATENSE (Timothy) 

Description. — Common timothy is a peremiial grass, from 
ij^ 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, live 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 earliness, 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 
spikelets 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 thaji 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 

222 



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PHLEUM PRATENSE 223 

by the lemma and palet. 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 alpinum) is common 
in meadows from Labrador to Alaska, in the mountains of both the East and 
the West, also Europe, Asia, and temperate South America. The inflores- 



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224 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. 

R^erences 

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: 1 31-136, 

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. 



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CHAPTER XIX 
SACCHARUM OFFICINARUM (Sugar Cane) 

Habit, Roots. — Sugar cane is a tall, perennial plant, re- 
sembling com 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. 

Inflorescencei 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 
IS ' 225 



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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, 191 6, by Albert Perry Brigham and Charles T 
McFarlane. American Book Company, Publishers.) 



is small, silky, and of low vitality. 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 



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SACCHARUM OFFICINARUM 227 

north of the latitude of 33°. The roots are unable to stand 
a temperature much lower than is^'F. 

Sugar from Sugar Cane. — The canes, stripped of their 
leaves, are first shredded by revolving spiked qylinders, 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 utiUzed 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 lime is added. The limed juice is heated with steam. 
The impurities unite with the lime, 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 crystallization is brought 
about. 

The grain of the sugar is imder 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 



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228 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 h^-s 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 



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CHAPTER XX 
LILIACEiE (Lay Famfly) 

Representatives of the Kly 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 
Draccenay 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, irt^he 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, like 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 are mostly linear, seldom divided or 
toothed, and not divided into petiole and blade. 

229 



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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 

Fig. 87. — Flower of onion ^ tr y 

(Allium cepa). 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, splitting (dehiscent) fruit with several united 
carpels. When the carpels split down the middl# 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. 



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LILIACEiE 



231: 



ALLIUM 

To this genus belong chives, gariic, leek, onion, shallot and 
Welsh onion. They are all herbs with a characteristic 



Fig. 88. — A, Welsh onion (Allium ascolonicum) ; B, cive (Allium schoeno- 

prasum) . 

alliaceous odor, which is due to the presence of allyl 
sulphide. 



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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 schcmoprasum) y 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 



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LILIACEiE 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. — A, base of stem of common onion (Allium cepa) showing hollow 
leaves cut across; 5, cross-section of hollow stem of same: C, base of stem of 
leek (Allium porrum) showing flattened solid leaves; Z>, 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 



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234 



BOTANY OF CROP PLANTS 



species, is the fleshy bases of leaves. In some spedes, as 
leek and shallot, the leaves are used as a seasoning in food. 
The leaves may be either flat or cylindrical (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 



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 



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LIUACE^ 



235 



filaments are 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 




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; «, endosperm; 
/, first true leaf; A, 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- 



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238 BOTANY OF CROP PLANTS 

ALLIUM PORRUM (Leek) 

Leek is a very robust biennial plant. The bulbs are 
small. The tall scape is solid and bears broad, solid, 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 tlie 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. 

ALLIUM SCHOSNOPRASUM (Chives or Cives) 

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 yoimg leaves are used in the seasoning of soups, ome- 
lets, and stews. The plants are also used, ornamentally, in 
garden borders. 

ALLIUM ASCALONICUM (ShaUot) 

This is a perennial herb with small, oblong-pointed bulbs 
about I inch in diameter and 2 inches long (Fig. 94). The 



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LILIACE^ 239 

bulbs are borne in clusters, but imlike 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) . 
ALLIUM 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." 



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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 earliest 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 earliest colonists 
brought the onion with them to America. 



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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 cepa var, multiplicans). 
Potato onions. 

Multipliers. 

2. Propagated by inflorescence bulblets or "tops" (Fig. 95) {Allium cepa 
var. bulbellifera). 

Top onions. 
Tree onions. 
Egyptian onions. 



Fig. 90. — Two common types of onions based upon shape of bulb. A, globe 
type; B, flat type. 



3. Propagated by seeds {Allium cepa). (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). 
(6) Bulbs small (Queen). 
16 



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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 English 
multiplier. The principal use of the "multiplier'' group is 
in the production of " bunchers " for the early market. There 
are both white and yellow "multipUers." 

In "/<?^," "/r^e," 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 



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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 called ^^peren- 
nial tree onions y 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 California. 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 
Prizetaker is our best example of a Spanish onion. Impor- 
tant varieties of Italian onions are the Barletta, White 
Italian Tripoli, 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, Silverkin and Strasburg. 

Composition of Onions.— Different 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 



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244 BOTANY OF 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 (^4. officinalis) , or perennial as in -4. laricinus, 
one of the ornamental asparagi. The stems are erect or 
climbing, in some instances (^4 . falcatus) reaching a distance 
of 25 feet or more. The small leaf-like structures along the 
stem, the so-called "leaves,'' are in reah'ty 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 



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LILIACEiE 



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 




Fig. 98. — Gaxden asparagus (Asparagus officinalis). A, pistillate flower; 
B, staminate flower; C, mature fruit; D, section of fruit; E and F, portions of 
the plant showing method of b anching, 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. The fruit (Fig. 98) 



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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 conmion 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 
'^hftmg^' 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 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 '0 and form the 



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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 or 
"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 



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248 



BOTANY OF CROP PLANTS 



nodes. Each flower is borne on a short, slender jointed 
pedicel (Fig. loo). The perianth is campanulate (bell- 
shaped), about 6 millimeters 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 — 



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LILIACE.E 



249 



staminate and pistillate flowers are borne on different 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 Flfty Plants Each, Staminate and Pistillate 





Fifty staminate 
plants, ounces 


Fifty pistillate 
plants, ounces 


First period, ten days 

Second period, ten days 


37 
104 
266 
203 


21 

68 


Third period, ten days 


164 


Fourth period, ten days 


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 
difiference 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. 



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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 five years, and may even retain their 
vitality 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 deUcate 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 njarket 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 Ught. 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. 



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LILIACE^ 251 

The Palmetto is grown most in the south, and is well-known 
on account of its resistance to asparagus rust {Ptu:cinia 
asparagi). 

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 

Bailey, 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., 94-98, 1887. 
GoFF, E. S.: Onion. 6th Ann. Rept. N. Y. State Agr. Exp. Sta., 190-214, 

1887. 
Green, W. J.: Asparagus. Ohio Agr. Exp. Sta. Bull. 9 voj. 3 (second series), 

241: 244, 1890. 
Gross, A. R : American Onions. Proc. Soc. Prom. Agr. Sci., 1 15-132, 1901 



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CHAPTER XXI 
MORACEiE (Mtilbeny 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 homes is Ficus elastica. Artocarpus 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 mxilherry (Papyrus papyrif era) , 
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 buds 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 



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MORACEiE 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 
hemp, and a synconium in figs. 

Key to Principal Genera 

Trees or shrubs. 

Flowers not in a receptacle; buds scaly, Morus (mulberry). 

Flowers inside of a hollow receptacle; buds naked, Ficus (fig). 
Herbs. 

Erect herbs, Cannabis (hemp). 

Twining herbs, Humtdus (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 

Pig. 1 01. — 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). 



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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 style* 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 imderstood, 
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 papyrifera) , a native of 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" {Rubus odoratus) 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. 



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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, and 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 J^ 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. — EconQmic 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 



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256 BOTANY OF CROP PLANTS 

is a very hardy, low, bushy tree with small fruit which varies 
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. muUicauUs) 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 1621, 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 



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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 meaHor 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 
staiminsiie inflorescences are i to 2 centimeters long. The pis- 
tillate inflorescences are from 5 to 8 millimeters long. The 
fruit is black, i to 2 centimeters long and has a deep red juice. 

Geographical. — Morus 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 {Morus rubra) y 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 



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258 BOTANY OF CROP PLANTS 

MORUS RUBRA (Red Mulbeny) 

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 
yoimg shoots deeply lobed, and with oblique and rounded 
sinuses, in the bases of which there are no teeth; they are 
roimded 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 
cyiindric. 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. 



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MORACEiE 



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. tj^^ 

Hop plants send out, near the i jf^ 

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- ^^^- ^""^''[^^flxll '^''^''^ 
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- 



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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 Stockberger as. a result of a 
number of experiments in which the plants were cut back, 
or primed, 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 



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MORACE^ 



261 





Fig. 103. — Hop (Humulus lupulus). A , portion of plant showing pistillate 
inflorescences; B, staminate inflorescence; C, rachis of pistillate inflorescence 
(•'hop"). 



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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- 



e 
\e 



Fig. 104. — Hop (Hamulus 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 



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HORACES 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 fertiUzed. Howard has shown that hops arti- 
ficially pollinated start to grow out at once, while those not 
polUnated 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- 



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264 



BOTANY OF CROP PLANTS 




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, 
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 ''lupulin'' (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 
layer of cells. Each cell has a 
rather thick cuticle. The secre- 
tion of the cells collects just 
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 quality 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 



Fig. 105. — Hop (Humulus lupu- 
lus). A, bract eole; B, immature 
lupulin gland; C, same in section; 
D, mature lupulin gland; E, same 
in section. (B-E after Percival.) 



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MORACE.E 26s 

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 California 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 



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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 



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MORACEiE 267 

acids in the hops tend to increase the acidity of the wort, and 
the ash adds to its mineral composition. 

FICUS (Fig) 

Habiti RootSy Stems. — Members of this genus are trees, 
shrubs or woody climbers (lianas). 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 hencg 1^- 
come trunk-Uke. Aerial roots may be sent down frotn 
branches, take root and also form trunks. The banyan tr:ee 
{Ficus benghalensis) 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. 



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268 BOTANY 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. 

Staminate 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 ovary and single style. The 
small nutlets are enclosed in the thick, succulent receptacle, 
forming a fruit known as a synconium (**fig'0- 

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, aurea and F, 
brevifoliaj are native to peninsular Florida and the Keys, 
while F. carica has been introduced into southern California 



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MORACEiE 269 

and a number of the Gulf States. As compared with other 
genera in the family Moraceae, Ficus is by far of the greatest 
economic importance. The most important species is Ficus 
caricdy the common fig of commerce. 

FICUS CAIUCA (Common Fig) 

Habit of Planti 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 roimd 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 trimcate 
or slightly heart-shaped. There are five to seven deep lobes, 
which are coarsely toothed or slightly lobed again; each lobe 
is blimt 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'O ^.t 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 



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270 



BOTANY OF CROP PLANTS 



perianth which is shorter than the stamens. The stamens 
vary from one to five; four is the ordinary number. 




Fig. 107. — Flowers of fig (Ficus carica). A, B and C, mule flowers; I>, 
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 loG after Kerner; H after Soltns-Laubach.) 

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 



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MORACEiE 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 pollination, 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 



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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 
foimd 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, 



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MORACEiE 273 

wasps from the second crop come to them, depositing eggs 
in the gall flowers. These figs, together with the eggs 
of the wasp, hibernate until March or April, 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 fertihzation. 
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 come to 
full maturity. Hence, it has been found necessary, in 
order to grow Smyrna figs, to resort to artificial fertiUzation. 

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 
18 



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274 BOTANY OF CROP PLANTS 

possessing pistillate flowers (mammoni) and those without 
pistillate flowers (profichi and mamme). The effects of 
fertilization may 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 
fertilized; 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 and 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 



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MORACEiE 275 

taken there to prevent the trees from winter-kilUng; 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, brevifolia) 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. 



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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. 



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MORACE^ 



277 



digitate, with five to eleven linear-lanceolate, pointed and 
serrate leaflets. Hemp is dioecious. The staminate 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 native home of common hemp is central and western 
Asia. It has spread, as a result of cultivation, throughout Europe, Asia and 
America. 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.) 



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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. 




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- 



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MORACE^ 279 

growing regions; and to the greater use of other fibers 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 imiformly 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 



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28o BOTANY OF 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 millimeters 
in length. They are of the best quality if the plants are cut 
when stamina te 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 



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MORACEiE 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 
capsularis 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 (Amaryllidaceae) 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 200,000,000 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. 



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282 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; 10: 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. t The Influence of Pollination upon the Development of the Hop 

(Humulus luptdus). . Plant World, 8: 281-283, 1905. 
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 Caprification. 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: 126 7- 129 2, 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. 



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MORACEJE 283 

Salmon,E. S.,andAMOS, A.: On the Value of the Male Hop. Jour. Southeast. 
Agr. Col., Wye, 17: 365-391^ 1908. 

Salmon, 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. 
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 Hop)s. Compt. 
Rend. Lab. Garlsberg, 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., 9 ser., 
19: 49-191, 1914. 

WiNGE, O. : The Pollination and Fertilization Processes in Humulus Lupulus 
L. and H. Japonicus Sieb. et Zucc. Comp. Rend. Lab. Carlsberg, 
11: 1-46, 1914. 



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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. — The 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- 
c e p t i o n s , are membranous, 
sheathing, and united to 

form a very characteristic structure, the ocrea (plu. ocreae) 

(Fig. no). 

284 




Fig. 1 10. — ^Leaf of common buckwheat 
(Fagopyrum vulgare). X i. 



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POLYGONACE^ 285 

Inflorescences. — The inflorescences vary a great deal 
within the family; in buckwheat they are panicled racemes, 
in Polygonum spp., 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 (resembUng 
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 filiform, 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 soUtary. 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 



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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, Eriogonum. 
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 



>bi 



Fig. III. — Rhubarb (Rheum) flower, external view, median lengthwise 
section, and with perianth and stamens removed. {After Lurssen.) 

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 



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POLYGONACEiE 287 

the season, there arise flower shoots, bearing elongated leafy 
inflorescences, crowded with small whitish flowers. Unless 
seed is desired, flower shoots should be promptly 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- 



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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. 



-^^persisfent jt^les 




persiMenfi 
calyjx lobe 



Fig. 113. — Fruit of rhubarb (Rheum rhaponticum). A, external view; B* 
cross-section. X 5. 

Self-polliiiation 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- 



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POLYGONACEiE 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- 
roimds 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 cUmates. 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. rhaponticum, 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, add 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 VULGARB (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. 

Steins. — 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 



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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 (Fagop3nrum 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. 



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POLYGONACEiE 



291 



InfiU>rescence. — 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. 





Fig. 115. — Common buckwheat (Fagopyrum vulgare). A, achene; B, 
floral diagram; C, cross-section of fruit; D, flower. {B after Wossidlo; C after 
Stevens.) 

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 



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292 BOTANY OF CROP PLANTS 

base of the fruit. There are eight stamens with glabrous, 
filiform filaments and oblong anthers. Three of the stamens 
closely surroimd 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. 

Dimoiphism and Pollination. — 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 other. 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-polli- 
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 



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POLYGONACEiE 



293 



more starchy than that of wheat, oats, barley, rye and com, 
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 
for this reason "middlings," 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. 




— jtencfcy 
ermsoerm 



Fig. 116- 



-Common buckwheat (Fagopyrum vulgare). 
seed. {After Stevens.) 



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 coimtry 
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 ol Fagopyrum, 
one of which, F, tataricuniy 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 wavy fruit angles. It is cultivated where a hardy sort is 



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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 conmion 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, 

Graii^large and not so plump, Japanese. 

Environmental Relations. — Buckwheat is a temperate- 
climate 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- 



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POLYGONACE^ 295 

wheat will grow well on poor soil — a soil that will not support 
true cereals. Therefore, it may be used as a green-manure 
crop. 

References 

Morse, J. F.: The New Rhubarb Culture. Orange Judd Co., 191 2. 
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, 191 2. 
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, 

1891. 



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CHAPTER XXIII 
CHENOPODIACEJE (Goosefoot Famfly) 

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 leaves 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 



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CHENOPODIACEiE 297 

are usually small, greenish, and bractless (SarcobatuSy grease- 
wood), or bracteolate (Beta), They are perfect {Beta), pis- 
tillate (Kochia), polygamous {Kochia), monoecious iSar- 
cohatus), or dioecious {A triplex spp.) They are usually regu- 
lar. There are no petals. The calyx is three- to five-lobed 
or parted, rarely of one sepal (Monolepis), or is entirely want- 
ing in the pistillate flowers of some genera {A triplex). The 
calyx is persistent in the fruit. There are usually as many 

stamens as lobes of the perianth, rarely fewer .. 

(Chenopodium spp.) ; the filaments are com- 
monly slender and bear longitudinally dehis- 
cent, two-celled anthers. The ovary is 
superior, free from the calyx and one-celled; 
the styles are terminal, short or elongated, 
one to three in number, and bear capitate 
stigmas. It has a single, erect ovule. 

Fruit. — The mature /rwi/ is a utricle (one- Fig. 117.—-^, 
seeded fruit with a loose pericarp) with mem- sarS)ba^s^^° b, 
branous, leathery, or thin pericarp. The annular embryo 
seeds may possess an abundance of endo- 
sperm {Betay Eurotia, etc.), or none {SarcobatuSy Salsola); 
the embryo is spirally coiled (Pig. 117) (Salsola) y annular 
{Beta)y or conduplicate {Salicornia). 

Key to Principal Genera 

Embryo spirally coiled (Fig. 117); endosperm little or none. 
Shrubs, Sarcobatus (grease wood). 
Herbs, Salsola (Russian thistle). 
Embryo not spirally coiled, partly or completely annular (Fig. 117); 
endosperm abundant. 
Flowers perfect (polygamous in Kochia). 
Calyx with five lobes, about the base of which is developed a wing, Kochia. 
Calyx wingless, persistent. 
Lobes of calyx becoming fleshy and bright red, Blitum (strawberry 
blite). 




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Lobes of the cdlyx not becoming fleshy, and never red in color. 
Developing large fleshy tap roots, Beta (beet). 
Tap roots not fleshy, Cheno podium (goosefoot, lamb's quarters, 
pig- weed). 
Flowers monoecious or dioecious. 
Bractlets silky-hairy, Eurotia (winter sage). 
Brae tie ts not silky-hairy. 

Pistillate flowers without a calyx, A triplex (orache). 
Pistillate flowers with a calyx, Spinacia (spinach). 

SPINACIA OLERACEA (Spinach) 

Description. — Spinach is an erect, smooth, annual herh. 
Early in the season, it throws out a number of large leaves, 
crowded near the ground surface. Somewhat later, a flower 
stalk is sent up to a distance of 2 or 3 feet. The leaves are 




penanti 
an 



Fig. 118. — Spinach (Spinacea oleracea). A, pistillate flower of prickly- 
seeded spinach; B, staminate flower of same; C, fruit of smooth-seeded 
spinach; D, fruit of prickly-seeded spinach. 

large, alternate, petioled, and triangular-ovate or arrow- 
shaped in outline. The flowers occur in axillary clusters. 
They are dioecious. The staminate flowers (Fig. 118, B) 
have a four- to five-parted calyx and four to five stamens 
inserted at the base of the perianth. Pistillate flowers 



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CHENOPODIACE^ 299 

(Fig. 118, A) have a two- to four-divided perianth which en- 
closes the fruit. The single ovary bears four to five stigmas, 
united at the base. The mature fruit (Fig. ii8, C, D) is a 
utricle consisting of a compressed seed surroimded by the 
cartilaginous calyx lobes, which are either smooth or spiny, 
and by a membranous pericarp. The seed is compressed, 
about the size of beet seed, and has an annular embryo 
surrounding the floury endosperm. 

Spinach is a native of southwestern Asia. It has become 
widely spread in cultivation. It is a cool-season crop re- 
quiring an abundance of water. It rims to seed in warm 
weather. 

Other Plants Named "Spinach." — There are two types 
of "spinach" which do not belong to the genus Spinacia: 
New Zealand Spinach {Tetragonia expansa) and Moimtain 
spinach, or orache (Atriplex kortensis). New Zealand 
spinach or New Zealand ice plant, is a member of the family 
Mesembryaceae, and a native of New Zealand. It is grown 
as simimer "greens." The plant is low, but profusely 
branching and spreading; the numerous, upright lateral 
branches are beset with tender leaves; the tips of these 
branches are the edible portion of the plant. The alternate 
triangular leaves are rather fleshy; the flowers are axillary, 
small, yellowish green, and without petals; the fruit is 
nut-like, and has one to nine locules, each of which is one- 
seeded. Mountain spinach or orache is more closely re- 
lated to the common species, belonging in fact, to the same 
tribe. It is a plant 4 to 6 feet tall, branching, and bears an 
abimdance of fruit. It not only differs from common spin- 
ach in its more erect habit but in its floral and fruit characters. 
The pistillate flowers do not have a perianth, but in fruit 
the seed is enclosed by a pair of compressed bracts which 
become enlarged and wing-like. 



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300 BOTANY OF CROP PLANT3 

Groups of True Spinach. — Kinney places the varieties of 
true spinach (Spinacia) into four types or groups, which may 
be distinguished by the following key: 

Key to Groups of Spinach 

"Seeds" prickly, Prickly-seeded group. 
"Seeds*' smooth. 

Ends and lobes of leaves rounded; plants compact in habit, Round-leaved 

group. 
Ends and lobes of leaves more or less pointed. 
Plants large, leaves long, and spreading on the ground. Thick-leaved 

group. 
Plants not so spreading, more vase-form and erect, on account of 
the stronger leaf stalks, Norfolk or Bloomsdale group. 

It was formerly thought that prickly-seeded spinach 
was more hardy than the smooth-seeded varieties, but a 
number of the latter have proven quite as hardy as prickly- 
seeded ones. Norfolk, Bloomsdale, Curled Savoy, and 
American Curled are important varieties in the Norfolk 
group; Victoria and Long Standing in the round-leaved group; 
Broad-leaved Flanders, Viroplay and Long Season in the 
thick-leaved group. 

Spinach is one of the foremost plants for *^ greens,'' or for 
use as a pot herb. 

BETA VULGARIS (Beet) 

Botanical Groups. — The above is the only species of the 
genus Beta of any economic importance. It is a complex 
species, however, separated into a number of rather distinct 
groups as follows: 

1. Sugar beet. 

2. Mangel-wurzels or mangels. 

3. Common garden beet. 



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CHENOPODIACEiE 3OI 

4. Leaf beets. 

(a) Chard or Swiss chard. 

(b) Ornamental or foliage beets. 

The Wild Beet. — Along the coast of southern Europe, 
there grows a perennial sea beet (Beta marUima) with a 
tough, slender root. It is considered by some that the culti- 
vated groups of beets have been derived from some form of 
this wild beet. 

SUGAR BEET 

Habit. — The sugar beet is a biennial, storing up food the 
first year in the crown (fleshy stem) and tap root from which 
aerial shoots are produced the second year. 

Root. — The "beet" itself is, for the most part, an enlarged 
tap root. The "crown" of the beet is developed from 
hypocotyl. The root part of the beet may be distinguished 
from the hypocotyl portion (stem) by the two opposite, longi- 
tudinal rows of secondary roots (Fig. 4). The tap root 
extends almost straight downward, and the lower portion be- 
comes small and thread-like and commonly reaches a depth 
of 4 feet and often 6 or 7 feet. The lateral roots and 
rootlets are very abimdant. The first 6 to 8 inches of the 
root, however, are almost free of side roots. The upper 
laterals are the largest of the branch roots and extend farth- 
est in the soil, spreading almost horizontally 2 to 3 feet. The 
lower laterals are more vertical, and those near the very tip 
almost parallel with the tap root. 

Stems. — The upper part (crown) of the sugar beet is 
hypocotyl, i.e., stem. This is a very much shortened fleshy 
stem with the leaves crowded at the apex. The second year, 
it sends up, from terminal and axillary buds, stout, angular, 
branching stems to a height of 3 or 4 feet; these stems give rise 
to flowering branches (Fig. 119). 



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302 BOTANY OF CROP PLANTS 

Shape and Structure of Beet (Tap Root and Hypocotyl) 

— Beet Shape and Size, and Sugar Content, — There is great 
variation in the shape and size of sugar beets. Some im- 
portance has been attached to the correlation between sugar 
content and beet shape and size. This relation, however, is 



.Fig. 119. — Sugar beet plant in full fruit. 

of little significance. Pritchard has recently shown that 
differences in the size and sugar content of individual beet 
roots are fluctuations, and show no evidence of inheritance. 
It is true that uniformity of type is desirable, but any attempt 
to judge of the sugar content of an individual beet by the 



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CHENOPODIACE^ 303 

shape and size is useless. Beets with a large crown are 
undesirable. 

Anatomical Structure and Sugar Content. — The researches 
of a number of European investigators have shown that the 
anatomical structure of the sugar beet is correlated with 
sugar content. In general, beets with a high percentage of 
sugar have a finer structure than those with a low percentage. 
A cross or lengthwise section of a beet shows it to be made up, 
for the most part, of a ground tissue penetrated by groups of 
vessels. In cross-section (Fig. 120), these groups of vessels 



Fro. 120. — Diagrammatic cross-section of sugar beet root. 

take a circular form, being separated from each other by par- 
enchyma tissue. At the center of the beet, the bundles are 
close together, forming the so-called "star. '^ The tissue that 
separates vessels is composed of two kinds of parenchyma 
cells: small cells surrounding the vessels, and large ones 
farther removed. The smaller parenchyma cells are rich in 
sugar, while the larger ones are principally water storage cells, 
poor in sugar. Hence, beets with a predominance of small- 
celled parenchyma are richer in sugar than those in which 
large water storage cells predominate. It must not be as- 



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304 BOTANY OF CROP PLANTS 

sumed from this that it would be possible to find conspicuous 
differences in the anatomical structure of beets varying i or 
2 per cent, in sugar. Furthermore, a certain microscopical 
appearance is not to be associated with a given sugar content. 
Distribution of Sugar in the Beet. — Fig. 121 shows that 
the beet root is divided into various zones differing as to their 



Fig. 121. — Diagram show- Fig. 122. — Sugar beet (Beta vulgaris), 

ing distribution of sugar in an A, flowers grouped in the axil of a bract; 

average sugar beet. {After B, cluster of flowers which fuse to form a 

Molinari.) multiple germ beet "seed." 

sugar content. The sugar content decreases from a point 
below the broadest portion of the root to the crown and tip. 
Crossing of Vascular Bundles in Crown, — In a longitudinal 
section of a beet, it will be seen that there is a crossing of the 
vascular bundles in the stem. The oldest part of the beet is 



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CHENOPODIACEiE 305 

the center; new rings of growth are placed upon these, while 
the new leaves come from the center of the crown. Hence, 
there is a crossing of the older and younger bundles that lead 
into the leaves. 

Rings of Growth. — The rings of growth vary in number, de- 
pending upon the length of the growing season. Ordinarily, 
six to ten rings complete their growth. The cambium rings 
arise in the pericycle, each remaining active but for a short 
period of several weeks. 

Leaves.— A cluster of large leaves is developed from the 
crown of the beet during the first season. The oldest leaves 




Pig. 123. — Beet (Beta vulgaris). A, floral diagram; B, flower, face view. 

{A after Bessey.) 

are on the outside, the youngest toward the center. Each 
leaf has a long petiole which broadens out at the base; the 
blade is large and roughly triangular in shape at the bas^, and 
longer than broad; the veins are prominent. 

Inflorescence. — The inflorescences are loosely spicate and 
terminal. The flowers are arranged along an axis, singly or 
in dense, sessile clusters, each of which is subtended by a small 
bract. Fig. 122, A shows a characteristic cluster of beet 
flowers in the axis of a bract. 

Flowers. — Beet flowers are perfect. The perianth consists 



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306 BOTANY OF CROP PLANTS 

of five parts united below to the base of the ovary (Figs. 123 
and 124). There are five stamens opposite to and partially 
attached to the perianth ring. The ovary is half-inferior, 
that is, partially imbedded in the flesh of the receptacle, one- 
celled and one- to three-seeded. There are two to three 
short, awl-shaped stigmas, united at the base. 

Pollination and Fertilization. — The beet flower is protan- 
drous. Shaw has shown that " self-fertilization '' (autogamy) 
does not take place, and that ** close 
fertihzation'^ (geitonogamy) is usu- 
ally ineffective. He has also demon- 
'^^ strated that thrips voluntarily travel 
from plant to plant, and positively 
assist in pollination of beet flowers. 
' j^^ ' Bees are of little consequence in this 

Fig. 124.— Diagram of process. Wind is the chief factor in 
h:?^rflo^fc°uti^a^: beet pollen dissemination. 
wise. (After Townsend and Fruit and Seed. — The ripened 
ovary of each flower is imbedded 
in the receptacle and the base of the perianth. The 
fruit is hard and nut-like, and contains a single, dark, 
smooth seed. The beet seed of the market is frequently 
called the ^^seed ball.'' The "seed ball" usually contains 
a number of germs; however, in some cases a single germ 
is produced. The multiple-germ beet seed arises when the 
flowers are in clusters; in this case, the parts of the several 
flowers stick together forming a several-seeded mass, the 
"seed ball." If the flower stands by itself on the stem, a 
single-germ beet seed is produced. The single flowers are 
usually located at points on the stem where a branch arises. 
According to this, a highly branched inflorescence will 
produce a greater proportion of single flowers. 

Tests of the comparative yields of beets from single-germ 



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CHENOPODIACEiE 307 

seeds and multiple-germ seeds have not been made. Of 
course, the advantage of single-germ seed is in the elimina- 
tion, to a large extent, of "thinning." Townsend and 
Rittue say that there is some indication that plants grown 
from single-germ seeds produce a greater number of single 
flowers than plants from multiple-germ seeds. It must be 
borne in mind that the so-called *^beet seed'' is in reality a 
fruit, that a multiple-germ seed consists of several one- 
seeded fruits, and a single-germ seed of one one-seeded 
fruit. 

The true seed is kidney-shaped and about the size of a 
turnip seed. The testa is thin, dark and smooth. The 
hilum and micropyle are basal. The white and floury endo- 
sperm lies in the middle of the seed, surrounded peripherally 
by the annular embryo (Fig. 117). 

Seed Production. — The beet industry in the United States 
has been dependent almost wholly upon Germany for its 
supply of beet seed. However, in the last year or so, con- 
siderable activity has been manifested in the growing of beet 
seed at home, and as a result, we are now growing success- 
fully large quantities of seed. Since the beet is a biennial, 
it is necessary to store the roots of the first year, and set 
them out the following season, in order to obtain seed. The 
"mother beets" may be tested for their sugar content before 
planting, and only those wliich show the desired percentage 
of sugar set out for seed production. The testing and 
selection of mother plants for seed has resulted in the striking 
improvement of beets. 

Germination/ and the Seedling. — The primary root is the 
first to appear. Soon, the cotyledons follow, pushing their 
way above groimd. The seedling consists of a very short 
hypocotyl which scarcely appears above ground, two rather 
fleshy, glabrous, short-petioled, one-nerved cotyledons, and 



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BOTANY OF CROP PLANTS 



a tapering primary root which gives off a few red, fibrous 
laterals. 

Types of Sugar Beets. — There are two well-known and 
common tyj>es of sugar beets: Klein wanzlebener and Vil- 
morin. The Vilmorin beet is of French origin, and as com- 
pared with the Kleinwanzlebener, a German beet, is more 
circular in cross-section, smaller, has a lighter skin, and a 
much smaller top of leaves. The secondary root lines are 
straight in Vilmorin beets, and spiral in Kleinwanzlebener 
beets. The percentages of sugar in the two t)^s are about 
the same. The tonnage of the Vilmorin is smaller. 

Compositioii oi Sugar Beets. — The following analyses of sugar beets were 
made by Headden.* 



German 
beet, 
grams 



Michigan I Colorado j Montana 

beet, I beet, beet, 

grams ( grams grams 



Average weight trimmed. j 

Water I 74550 

Dry substance I 25 . 450 

Sugar I 16.600 

Total ash | o. 800 

Protein j o . 706 



813.000 
78.000 
22.000 

15300 
0.701 
0.769 



673.000 

75.800 

24.200 

18.300 

0.820 

0.543 



479 300 

74 603 

25-370 

18.240 

2.680 

0.436 



Except in extreme cases, there seems to be little support for the statement 
that the greater the weight the less the sugar content of the beet. The com- 
position of the beet is affected by age, disease, fertilizers, insufficient food 
supply, light, time of topping, rainfall, etc. The average sugar content of 
American grown beets is about 15 per cent. Frequently, the yields are more 
than 20 tons, and the sugar content 17 to 20 per cent. 

Manufacture of Sugar. — The chief use of sugar beets is in 
the manufacture of sugar. The beet sugar industry has made 
very rapid development in this country. In the making of 
beet sugar, the topped beets are first washed, and then cut by 

' Colorado Agri. Exp. Sta. Bull. 183. 



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CHENOPODIACEiE 309 

machinery into narrow strips (^'cossettes'O- These strips 
are placed in diffusion vessels, treated with water at a tem- 
perature of about 80 to 84^0., and the sugar extracted by 
diffusion. The juice is then run into large tanks, where milk 
of lime is added to it. The liming is followed by the intro- 
duction of carbonic acid, which precipitates the lime as a car- 
bonate and salts of the acids of the juice. The precipitate 
carries down most of the impurities in the juice. When the. 
first '^carbonatation*' process is about completed, the juice 
is heated nearly to the boiling point, filter-pressed, and the 
filtrate lead into a second carbonatation tank. This may be 
followed by a third carbonatation. The purified juice is 
concentrated by boiling, and crystallization brought about 
in vacuum evaporators. The material that comes from the 
vacuum evaporators is a mixture of crystals and molasses. 
This mixture ("masscuite") is placed in centrigufal machines 
lined with fine sieves; here the molasses is driven out and the 
sugar retained. The sugar is next fed into the granulator, 
where the crystals are separated from each other during the 
drying process. The molasses from the first boiling is again 
boiled, and further crystallization brought about. 

By-products of Manufacture. — After the sugar has been 
removed from the sliced beets, there is left a substance known 
as ''beet pulp." This is a valued stock food. However, it 
cannot be made the sole ration of an animal, as it is deficient 
in nitrogenous food materials. Beet pulp is sometimes dried, 
mixed with molasses, and fed to dairy cows. Molasses from 
the second boiling is also valued as a stock food. The refuse 
that accimiulates in the purification process is sometimes 
employed as a fertilizer. It has been demonstrated that it is 
possible to manufacture fusel oil, alcohol, rum, and vinegar 
from the refuse molasses. There are many other ways of 
utilizing sugar-beet molasses. 



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COMMON GARDEN BEET 

The botanical characters of the garden beet are very similar 
to those of sugar beet. As is well known, however, they are 
not so rich in sugar and dififer from them in color, shape, and 
edible qualities. 

Types. — As to color, there are two main groups of garden 
beets: (i) Flesh red (Early Blood Turnip, Eclipse, Egyptian, 
Detroit, Dark Red); and, (2) Flesh yellow (Early Yellow 




Pig. 125. — Percentage of the world's supply of beet sugar'(raw) produced in 
the different countries, campaign of 19 13-14. 



Turnip, Golden Globe). Goff divides garden beets into four 
types as to shape: 

1. Root oblate or top-shaped (Early Blood Turnip, 
Eclipse, Egyptian, etc.). 

2. Root half long (Victoria). 

3 . Root oval (Strasbourg Pear-shaped, Dell's Black-leafed) . 

4. Root long-conical (Long Blood, Long Yellow). 

Uses. — Garden beets are mostly for table use. The flavor 
of early varieties is more delicate than that in later maturing 
ones. The roots are boiled, pickled, or mixed in salads. 
Considerable quantitites are canned, and in some cases the 
common garden sorts are used for stock food. 



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312 BOTANY or CROP PLANTS 

CHARD 

The edible "leaf beets'' go under various names: Spinach 
beet, sea-kale beet, Swiss chard, silver beet, chard, and 
Beta cycla. The 'flowers and fruit are like those of the 



Fig. 127. — Chard or leaf beet (Beta vulgaris). 

common beet. Cultivation has changed its habit of growth, 
however, such that leaves, instead of roots have become 
developed. 



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CHENOPODIACE^. 



3^3 



The plant is a biennial with a somewhat branched and 
thickened, but not fleshy, root system. The leaves are 
clustered at the surface of the ground (Fig. 127); they bear 
large, thick leaf stalks and large blades. The leaf stalks 
are often as much as 2 feet long and i to 3 inches thick. 

The chief variety grown in this country is LucuUus, one 
in which the leaves are heavily crumpled or "savoyed." 
Swiss chard is a variety with dark, green leaves. There 
are forms of chard with white, red or pink leaf stalks. 

Chard is grown for its tender leaves and petioles. The 
leaves are boiled like spinach, and the petioles are served like 
asparagus. 

MANGEL-WURZELS OR MANGELS ■ 

To this group belong the stock-feeding varieties of Beta vuh 
garis. The botanical characters are very similar to those 
given for the sugar beet. 




Fig. 128. — Types of mangels. A, long; B, intermediate; C. tankard; D* 
globe. (After Percival.) 

Types. — As to shape, there are four well-recognized types 
of mangels (Fig. 1 28) : 

1. Globe. — In these varieties, the roots are globular, and 
project above ground for more than half their length (Yellow 
Globe, Orange Globe). 

2. Tankard. — Varieties of this type have roots which are 



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314 BOTANY OF CROP PLANTS 

almost cylindrical, and narrow abruptly at both ends. The 
roots are comparatively small (Golden Tankard). 

3. Oval or ^^ Intermediate.^^ — The roots in these are oval, 
and intermediate in shape between globe and long varieties. 
They vary in color (Giant Intermediate). 

4. Long. — Roots of this type are several times longer than 
broad and project above the soil for a considerable propor- 
tion of their length. They are heavy yielders. Both red 
and yellow-skinned varieties (Long Red, Long Yellow) occur. 
The ox-horn varieties have long twisted and horn-like roots. 

Composition and Uses. — The mangels vary in sugar con- 
tent from 3 to 8 per cent., the Golden Tankard and Globes 
having the highest percentage. Long varieties are relatively 
low in sugar content but produce a greater tonnage per acre. 
The water content varies from 85 to 92 per cent. Mangels 
are being extensively grown for stock food. They are 
one of the most important root crops. The root crops 
include all plants whose underground vegetative parts, such 
as rootstocks or roots, are utilized. Bulbs and tubers, 
however, are usually excluded. Examples of root crops are 
beets, mangels, turnips, carrots, rutabagas, sweet potatoes, 
and artichokes. Root crops are used for human food and 
also for forage. It must be kept in mind that all "root 
crops" are not wholly roots, morphologically, but that in 
some, such as the carrot, turnip, rutabaga, mangel and beet, 
the lower two-thirds or more of the underground part is 
root, the remainder stem ("crown")- Practically all 
root crops are best adapted to localities with a cool growing 
season. 

References 

GoFF, E. S.: Vegetables: Garden Beet. 6th Ann. Rept. N. Y. Agr. Exp. 

Sta., 120-132, 1887. 
Kinney, L. F.: Spinach. R. I. Agr. Exp. Sta. Bull. 41: 99-131, 1896. 



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CHENOPODIACEiE 315 

Pritchard, F. J.: Some Recent Investigations in Sugar-beet Breeding. 

Bot. Gaz., 62 : 425-465, 1916. 
RuGGEBERG, H.: Beitrage zur Anatomie der Zuckerriibe. Mitt. Kaiser 

Wilhelms Inst. f. Landw. Bromberg, 4: 399-415, 191 2. 
Shaw, G. H.: Thrips as Pollinators of Beet Flowers. U. S. Dept. Agr. 

Bull. 104: 1-12, 1914. 
TowNSEND, C. O., and Rittue, E. C: The Development of Single-germ Beet 

Seed. U. S. Dept. Agr. Bur. Plant Ind. Bull. 73: 1-23, 1905. 
TowNSEND, C. O.: Single-germ Beet Seed. Jour. Hered., 6: 351-354, 191 5. 



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CHAPTER XXIV 
GROSSULASIACEiE (Gooseberry Fanuly) 

There is but one genus — Ribes — in this family. It includes 
the gooseberries and currants. 

Stems. — Gooseberries and currants are erect or procum- 
bent shrubs. The stems of gooseberries are armed with 
spines and prickles, while currants have neither of these 
present on the stems. The spines and prickles of gooseberries 
are stem emergences, thus differing from those of certain 
plums and thornapples, which are reduced branches. Some 
cultivated varieties of gooseberries are almost thornless. 
In gooseberries the fruit is borne on one-year-old wood and 
from spurs (short branches) on older wood. As a rule, these 
spurs only bear well for the first two or three years. Black 
currants produce the most fruit on wood that is one year old, 
while red and white currants produce fruit most abundantly 
on spurs that arise from wood two or more years old. When 
the canes (^' stems") reach an age of four or five years their 
yield decreases, and hence it is the practice to prune out old 
canes, and keep a supply of new ones coming on. The cut- 
ting back of old canes not only induces the formation of 
fruit spurs, but new canes as well. Propagation of both 
gooseberries and currants may be made by stem cuttings; 
gooseberries are also propagated by layering^ and occasionally 
from root cuttings. In layering, the branches are bent over 
and covered with earth; after the buried stems take root, 
the newly rooted part is severed from the parent plant. 

316 



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GROSSULARIACEiE 317 

Leaves. — The leaves are alternate, palmately lobed, often 
reginous-glandular or viscid. Stipules are wanting or pres- 
ent. In all gooseberries and most currants, the leaves are 
plicate (Fig. loi) in the bud. In a few cases, as the golden 
currant (Ribes aureum), they are convolute (Fig. loi). 

Inflorescence and Flowers. — Currants and gooseberries 
usually have a typical racemose type of inflorescence; rarely 
the flowers are solitary. Each pedicel is subtended by a 



Fig. 129. — A, flower of red currant (Ribes rubrum) in lengthwise section; 
B, flower of golden currant (Ribes aureum). The portion designated calyx- 
tube is in reality toral tube. (A afUr Sargent.) 

bract and usually also bears two bractlets at about the 
middle. The flowers are perfect, regular, with calyx and 
corolla both present and well differentiated (Fig. 129). The 
receptacle (torus) is cup-shaped and surrounds the carpels 
(Fig. 130). The calyx is divided into four or five lobes, 
often colored. There are four or five very small petals, 
scale-like and alternating with the calyx lobes; the petals 
are free, and inserted on the throat of the calyx tube. The 



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BOTANY OF CROP PLANTS 



stamens are of the same number as petals, and are usually 
included, and attached to the perianth. The inferior ovary 
is one-celled with two parietal placentae, each bearing 
numerous ovules; two more or less united styles are present. 

PoUinatioiL — Gooseberries and currants are cross-polli- 
nated, for the most part. Insects are the chief agents in 
pollination. 

The Mature Fruit. — The fruit of the currant and goose- 
berry has been regarded as a berry; that is, a true fruit 



vascular bundle 
Of receptacle 




"""^^^J^lbondle 



Fig. 130. — Diagrammatic cross-section of Ribes flower prior to fertiliza- 
tion. Note that carpel tissue is surrounded by receptacle tissue, as is evi- 
denced by the two distinct sets of vascular bundles. The fleshy part of the 
Ribes fruit is thus seen to be composed of receptacle tissue for the most part; 
hence the fruit is not a berry, morphologically, but rather pome-like. (Dia- 
gram front microscopic section and data furnished by E. J. Kraus.) 

possessing numerous seeds more or less imbedded in a fleshy 
endocarp and mesocarp. Recent, unpublished work of 
Kraus establishes the fact that the fruit is in reality pome- 
like in its structure. A cross-section through the base of 
the flower or through the fruit shows two distinct sets of 
vascular bundles (Fig. 130), the outer belonging to the re- 



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GROSSULARIACE^ 3 1 9 

ceptacle and leading to the sepals, petals and stamens, the 
inner to the carpels. Thus it is seen that a large portion of 
the flesh of the Ribes fruit is toral and not carpellary. 
Toral or receptacle tissue and carpellary tissue imperceptibly 
grade into each other. 

Seeds. — The seeds are small, and slightly flattened on one 
side. The outer layer of the seed coat is comparatively thick 
and gelatinous and the inner layer is thin. There is an 
abundance of endosperm. A minute embryo occurs at the 
base of the seed. 



Geographical. — There are about loo species of the genus Ribes. These are, 
for the most part, natives of temperate Europe, Asia, North America and the 
Andes of South America. 



Key to Important Species of Genus Ribes 

Stems with one to three thorns below the clusters of leaves, often with nu- 
merous scattered prickles on the branches, sometimes upon the fruit 
also. Leaves plaited in the bud (Fig. loi) (Gooseberries). 
Fruit unarmed and smooth; spines on the branches generally solitary 
(sometimes triple) and slender. R. oxyacanthoides (common gooseberry) . 
Fruit armed with prickles, or rough and glandular-hairy; spines on the 
branches usually three together, stout. R. grosstUaria (European 
gooseberry). 
Thornless and prickleless; leaves plaited in bud (Fig. loi); racemes few- to 
many-flowered (Currants). 
Torus dilated immediately above the ovary. 
Leaves without resinous dots beneath; fruit red or light. R. rubrum 

(garden currant). 
Leaves with resinous dots beneath; fruit black. R, nigrum (Euro- 
pean black currant). 
Torus prolonged above the ovary into a campanulate, cylindrical 
tube. R. americanum (American black currant). 
Thornless and prickleless; leaves convolute in the bud (Fig. loi); racemes 
several flowered; torus above much elongated, bright yellow. R, aureum 
(Missouri, flowering, golden, or Buffalo currant). 



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320 BOTANY OF CROP PLANTS 

CURRANTS 

Species. — There are four principal species of currants in 
American currant culture. 

(i) Ribes rubrum {R. vulgar e) includes all our red and 
white varieties, and is the most important species commer- 
cially. The leaves are hairy at first, but become smooth with 
age. The small, greenish-yellow or purplish flowers are in 
drooping racemes. The fruit varies in color; it may be 
bright red, yellowish, white, or striped. This species is foimd 
growing wild from New England to Minnesota and north- 
ward; also in Europe and Asia. Commercially, its culture is 
restricted to northern latitudes. Important varieties are 
Victoria, Red Dutch, Cherry, Versaillaise, Fay, Prince 
Albert, and White Grape. 

(2) Ribes nigrum, the European black currant, is but little 
cultivated in America. It differs from the preceding in 
several respects: the lower surfaces of leaves are covered with 
yellow, resinous dots, and the fruit is black. The greenish- 
white flowers are in drooping racemes, and the fruit and 
toral tube are both hairy and resinous-dotted. This currant 
is a native of middle and northeast Europe, through northern 
Asia to Manchuria and northern China. 

(3) Ribes atnericanum, the native wild black currant of 
America, is not cultivated to any extent. The plant has a 
spreading habit. As in the European black currant, the 
lower surfaces of leaves are resinous-dotted, and the fruit is 
black in color, but it differs from the European species in that 
the toral tube and fruit are not resinous. It is distributed 
from Nova Scotia and New England south to Virginia and 
westward to Colorado and Manitoba. 

(4) Ribes aureum is the chief American flowering currant. 
It is cultivated principally as an ornamental shrub, but also 



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GROSSULARIACE^ 32 1 

for its fruit. The wedge-shaped leaves are three-lobed, 
smooth, and resinous when yoimg. The short inflorescence 
is very leafy. The most characteristic feature of the plant is 
its flowers (Fig. 129, B) which have a long, tubular, yellow 
toral tube, and small reddish petals. The fruit is dark 
brown or black. The species is native to the Mississippi 
Valley, and westward to the Rocky Mountains. Important 
varieties are Crandall, Deseret and Jelly. 

Uses. — Currants are made use of for jelly, pies, sauce, and 
wine. 

GOOSEBERRIES 

Species. — The cultivated gooseberries belong to two 
species: Ribes grossulariaj of Europe, and Ribes oxyacan- 
thoides {R, hirtellum), of America. European gooseberries, 
as compared with American sorts, are less productive, less 
hardy, not so easily propagated by cuttings, have a thicker 
skin, a poorer quality of fruit and are less resistant to Ihe 
common gooseberry mildew {Sphcerotheca mors-uvce). 

Ribes grossularia. — This is a robust plant, bearing large 
thorns, usually in threes. The leaves are shining and 
pubescent. The flowers have a pubescent toral tube and 
fruit. The large berry is rough, hairy or prickly, red, green- 
ish, or yellowish in color. The species is a native of 
Europe, northern Africa and western Asia. 

Ribes oxyacanthoides. — The American gooseberry is not 
as robust as the preceding. The thorns, sometimes in 
threes, sometimes single, are much more slender, and in 
some varieties may be entirely wanting. The leaves are 
shining and finely hairy. The greenish or purplish flowers 
have a smooth or hairy toral tube and a smooth fruit. The 
small berry is perfectly smooth, and reddish in color. Ribes 
oxyacanthoides grows from Newfoundland to New Jersey 



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322 BOTANY OF CROP PLANTS 

and westward to the Rocky Mountains. Important varie- 
ties are Downing, Pale Red, Red Jacket, Champion and 
Pearl. There are hybrids between the American and 
European species. 

Uses. — Gooseberries are used either green or ripe. They 
are made into pies, jelly, wine, and stewed or canned. 



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CHAPTER XXV 
CRUCIFERiE (Mustard Family) 

This family is of world-wide distribution. There are in 
the neighborhood of 2,000 species in 180 genera. The largest 
number of genera and species is found in southern Europe 
and Asia Minor. They are 
found from low to high latitudes 
and from low to high altitudes. 

Many of the genera yield crop 
plants, such as cabbage, turnip, 
rutabaga, rape^ black mustard, 
white mustard, radish, water 
cress and horse radish, while a 
number of genera include per- 
nicious weeds, such as penny 
cress, wild mustard or charlock, 
shepherds purse, false flax, and 
tansy mustard. 

Stems, Leaves. — Most mus- 
tards are herbaceous; a few are 
woody. The sap is usually 
watery and acrid. The leaves 
are alternate, simple, and vari- Pig. 131.— -Cmciferae. Floral 

, , , J J. , J rn-i diagram above; flower in median 

OUSly lobed or dissected. The longitudinal section below. 

stipules are wanting. 

Inflorescence and Flowers. — The predominant type of 
inflorescence is a terminal raceme; rarely'^the flowers are 
solitary at the end of a scape. The mustard flower is char- 

323 



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324 



BOTANY OF CROP PLANTS 



acteristic (Fig. 131). It is perfect and regular with four 
sepals, four petals, six stamens (two short and four long), 
and a two-celled ovary. The four sepals are entirely dis- 




FiG. 132. — Common garden radish (Raphanus sativus). In flower, on 
right; and in fniit, on left. Note the characteristic racemose inflorescence 
with flowers at the apex and fruit at the base. 

tinct, but often overlapping; the two outer are narrow, and 
the two inner may be narrow also, but often are distinguished 
from the outer by being concave or saccate at the base; they 



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CRUCIFERiE 



325 




are in two distinct whorls. The four petals are so arranged 
that when one looks at the face of the flower, it has the 
appearance of a Greek cross, hence the name Cruciferae 
(Latin, crux, cross, +feray to bear). The petals, as a rule, 
are clawed, that is, have a narrow or stalk- 
like base at the tip of which is a broader 
blade; they are similar as to size and shape. 
Nectar glands are frequently found at the 
base of petals. The six stamens are in two 
whorls, the outer two opposite each other 
and opposite the two sepals of the inner 
whorl, and with short filaments, the inner 
four stamens opposite the petals and with 
long filaments; the anthers are two-loculed 
(rarely one), and longitudinally dehiscent. 
The single pistil is superior, usually sessile, 
compoimd, and has a single style with a 
more or less two-lobed or disk-shaped stigma; 
the ovules are attached to two parietal 
placentas, which are connected by a "false." 
partition, an outgrowth of the placentas 
themselves. 

Fruit — The ovary develops into a pod-like 
fruit (Fig. 133), which is termed a silique 
(Brassica) when long and slender, and a 
silicle (Bursa) when short and broad. The 
sides (valves) of the fruit separate at dehis- 
cence, leaving the two placentas and false 
partition. In a few genera {Raphanus, radish), the fruit is 
indehiscent. 

Seeds. — ^The seeds are usually many, attached to both 
sides of the partition, and have a mucilaginous testa; the 
endosperm is lacking; cotyledons are incumbent (with their 



Fig. 133. — Fruit 
of cabbage (Bras- 
sica oleracea capi- 
tata). A, exter- 
nal; B, cross-sec- 
tion. 



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326 BOTANY OF CROP PLANTS 

back against the hypocotyl), accumbent (margins folded 
against the hypocotyl), or conduplicate (folded upon them- 
selves lengthwise). 

The seeds of mustards, like those of grasses and composites, 
are short-lived, as compared with those of the mallow family, 
potato family and pea family. Longevity of seeds is due to 
a number of factors, chief of which is impermeability of the 
seed coats to water and oxygen. Seeds with permeable coats 
are more sensitive to moisture and temperature changes than 
are those with impermeable ones. When moisture is absorbed 
by the seed its rate of respiration is increased, and hence its 
vitahty reduced. This may be an important factor in 
shortening the life of the seed. 

Closely Related Families.— Members of the mustard family may be mis- 
taken for those of the poppy family (PapaveracecB) or caper family {Cappari- 
dacece), both of which are closely related. The poppies have perfect flowers 
usually with two early deciduous sepals, while capers are distinguished from 
mustards by the six approximately equal stamens and by the one-celled 
capsule. 

Key to Principal Genera 

Pod indehiscent, Raphanus (radish). 
Pod dehiscent into two valves. 
Pod a silique, at least twice as long as wide. 
Leaves dissected, Sophia (tansy mustard). 
Leaves broadly-lobed. 

Silique beaked by a persistent style) ; seeds in one row, Brassica 
(cabbage, turnip, rutabaga, rape, black mustard and white mustard). 
Silique beakless; seeds in two rows, Radicula (water cress and horse 
radish). 
Pod rarely more than twice as long as broad. 

Silique not flattened, nearly circular in cross-section, Camelina (false 

flax). 
Silique flattened. 
Silique elliptic or oval, Lepidium (penny cress). 
Silique triangular-obovate or obcordate. 

Basal (radical) leaves pinnatifid, Capsella (shepherd's purse). 
Basal leaves entire or merely toothed, Thlaspi (penny cress). 



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CRUCIFERiE 327 

BSilSSICA 

Generic Description. — This genus includes annual (black 
mustard), biennial (turnip), or perennial (cabbages under 
their^natural conditions) herbs. The root system may be 
fleshy (turnip), or rather woody and solid (cabbages). The 
basal (radical) leaves are frequently pinnatifid, while those 
of^the stem (cauline) are entire, dentate, or broadly lobed. 
The large, yellow flowers are in elongated racemes. The 
sepals, petals, and stamens are as described for the family. 
The silique (Fig. 133) is elongated, sessile, terete or four- 
sided, and tipped with an indehiscent, conic, usually one- 
seeded beak; the valves are convex, one- to three-nerved, 
the lateral ones often flexuous; the septum (partition) is 
membranous or spongy; at the tip of the silique is a short or 
elongated style tipped by a truncate o?. two-lobed stigma. 
The seeds are in one row in each cell. 

Pollination. — Representatives of the genus are for the most 
part insect pollinated. It appears that both self- and cross- 
pollination takes place. 

Seedling. — ^At germination of the seed, the cotyledons are 
brought above ground. In all representatives of the genus, 
the cotyledons are emarginate (notched at apex), unequal 
in size, and three-nerved at the base. 

Geographical. — ^There are about 80 species in the genus Brassica, chiefly 
occurring about the Mediterranean region; some are now cultivated, however, 
in boreal and subtropical regions of Europe, Asia, Africa, and North and South 
America. None of the Brassicas are native of America or Australia. 

Key to Principal Species of Genus Brassica 

Leaves of flowering stem not clasping; annuals; sepals spreading. 
Seeds small, reddish-brown; valves of silique one-nerved, B, nigra (black 

mustard). 
Seeds large, pale yellow; valves of silique three-nerved, B. alba (white 
mustard). 



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328 BOTANY OP CROP PLANTS 

Leaves of flowering stem somewhat clasping; biennials; sepals erect. 
Roots swollen and fleshy. 
Young leaves glaucous; a distinct short stem on upper part of root, B. 

campestris (rutabaga or Swede turnip). 
Young leaves grass-green; no distinct short stem on upper part of root, B, 
rapa (turnip). 
Roots not fleshy. 

Young foliage covered with a few hairs, B. napus (rape). 
Young foliage smooth, B. oleracea (cabbages, etc.). 

BRASSICA OLERACEA (Cabbages, etc.) 

Wild Cabbage. — This is the parent of the various forms 
of cultivated cabbage. It grows wild along the coasts of 



Fig. 134. — ^Wild cabbage. (After Bailey.) 

England and Wales, Channel Island, and western and south- 
em Europe. It is a stout perennial or biennial from a tough 
and woody root. The stem is branching and attains a 
height of I to 2 feet (Fig. 134). The lower leaves are stalked, 
lyrate or pinnatifid, entire, and broad, while the upper ones 
are sessile and much smaller. There is no tendency to form 
heads in the wild form. The flowers are in elongated 
racemes and are rather large, about ^i to i inch in diameter, 
and of a pale yellow color. The fruit is a smooth silique 
often 3 or 4 inches long. 



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CRUCIFER^ 329 

Cultivated Types of Cabbages. — ^A number of types have 
arisen, probably as mutants, from the native wild cabbage. 
The modifications concern the stem as in kohlrabi, the foliage 
as in kale, head cabbage, and Brussels sprouts, and inflores- 
cence, as in broccoli and cauliflower. The characteristic 
differences between these are shown in the following key: 

Key to Cultivated Types or Cabbages 

Stem of first year elongated. 
Stem branched and leafy; plant much resembling wild cabbage (Fig. 135), 

B. oleracea vat. viridis (kales and collard). 
Stem unbranched, the axillary buds developing into small heads (Fig. 136), 

B. oleracea var. gemmifera (Brussels sprouts). 



Fig. 135. — Kale (Brassica oleracea Fig. 136. — Brussels sprouts (Brassica 
viridis). (After Vilnwrin.) oleracea gemmifera). 

Stem of first year short. 
First-year stem forming a "head** (Fig. 137), B. oleracea var. capUata 

(common cabbage). 
First-year stem not forming a "head.** 



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330 BOTANY OF CROP PLANTS 

Turnip-like stem which stands mostly above {ground. (Fig. 138), B 

okracea var. caalo-rapa (kohlrabi). 
Stem not tumip-like, leafy below, inflorescence partially developing 

first season (Pig. 139), B. oteracea var, hotrylis (cauliflower, broccoli). 

BRASSICA OLERACEA VAR. VIRIDIS (Fig. I35) 

The members of this group resemble very much the wild 
form of cabbage. The terminal and lateral buds elongate 
during the first season, giving the plant a branching habit. 
Forms of this variety are known as kale, borecole, marrow 
cabbage, or coUard. CoUards are grown in the South par- 
ticularly. This southern form is known as the Georgia 
coUard. Marrow cabbage or marrow kale is a broad-leaved 
form. There are a number of kales with finely dissected 
leaves; among such are the well-known Scotch kales, rather 
common market sorts. The tree kales have straight, stiff 
and strong stems often 3 or 4 feet tall; the dwarf kales are 
lower and close to the groimd. Dwarf Green Scotch Kale 
is the most common sort grown in the Norfolk truck-garden- 
ing area. Thousand-headed kale is a very large, highly 
branching forni. The large-leaved kales, such as marrow 
kale and thousand-headed kale, are used as stock food. The 
finer-leaved varieties are used as a boiled green vegetable. 

Unlike their close relatives, Brussels sprouts, head cabbage, 
kohlrabi and cauliflower, kale and coUard will endure the 
heat and drought of summer, and kale, at least, will stand 
considerable freezing. 

BRASSICA OLERACEA VAR. GEMMIFERA (Brussels sprouts) (Fig. 136) 

Here belong those cabbages in which the axillary buds 
develop into small heads or "sprouts.'' These are formed 
in the axils of leaves. The mam stem is elongated and 
imbranched. The first "sprouts" to appear are those at the 
base of the stem, subsequent ones appearing in order from 



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CRUCIFERiE 331 

below upwards, almost to the top of the stem. Brussels 
sprouts resemble the kales except that the axillary buds, 
instead of developing into side branches, do not elongate but 
develop into "heads,'' which are in reality specialized buds, 
usually I to 2 inches in diameter. 

Types. — There are two general types of this plant: tall 
Brussels sprouts and dwarf Brussels sprouts. The former 
type grows to a height of 2 to 3 feet, is rather slender, and 
the leaves and "sprouts" are comparatively far apart. It 
is not grown to any extent in this country; dwarf varieties 
are preferred here. These latter seldom exceed 2 feet in 
height; they have a stout stem upon which the leaves and 
"sprouts'' are crowded. As a rule, the leaves of the dwarf 
type are more crimped than those of the tall type. All the 
types are cool season plants. 

Uses. — Brussels sprouts are much more tender than com- 
mon head cabbage. The smaller "sprouts" are the most 
desirable. They are cooked in a manner similar to cabbage. 





Fig. 137. — Common head cabbage (Brassica oleracea capitajba). Three com- 
mon types of heads: A, pointed or oblong; J5, ballhead; C, drumhead. 

BRASSICA OLERACEA VAR. CAPITATA (Common Head Cabbage) 

(Fig. 137) 
The common head cabbage produces, the first year, a short 
stem upon which are found numerous, thick, overlapping, 



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334 BOTANY OF CROP PLANTS 

BRASSICA OLERACEA VAR. BOTRYTIS 
(Cauliflower, Broccoli) (Fi& 139) 

Cauliflower and broccoli are types of cabbage in which 
there is a large "head/' composed of abortive flowers upon 
very much modified, thickened flower stems (Fig. 139). The 



Fig. 139. — Cauliflower (Brassica oleracea botrytis). Ay entire plant; JB, 
portion of "head." 

metamorphosed inflorescence develops the first season, its 
numerous short, fleshy, and closely crowded flower stalks 
forming the head, as indicated above. Subtending the head 
are a number of cabbage-like leaves. In growing the vege- 



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CRUCIFERiE 335 

table, these basal leaves are tied up about the fleshy, white 
head to prevent its browning by the sun. 

A distinction is made between cauliflower and broccoli. 
The latter requires a longer time to mature than cauliflower; 
furthermore, the heads are smaller and the leaves broader, 
narrower, stiffer and more numerous. 

Cauliflower and broccoli are both cool-season crops. 

BRASSICA RAPA (Turnip) 

Description. — The common turnip is a biennial. The 
first year aWollen and fleshy tap root is formed. However, 
the " turnip '' is combined primary root and hypocotyl. The 
upper portion to which the leaves are attached is stem, while 
the lower portion to which secondary roots are attached is 
root. 

The leaves that arise from the " turnip '^ the first season are 
in the form of a rosette. They are oblong to oval, some- 
times entire, serrate, or the later ones pinnate or pinnatifid. 
First-year leaves are grass-green and rough-hairy. The sec- 
ond season, a stem i to 3 feet tall is sent up from the ter- 
minal bud in the center of the rosette of leaves, which bears 
alternate, clasping, lanceolate or oblong, entire or dentate, 
smooth leaves. The flower stem is branching. The inflores- 
cence is a raceme. The flowers are bright yellow, about J^ 
inch in diameter and of the characteristic mustard type. 
The fruit is ij^ to 2 inches long, cylindrical, and tipped by a 
short beak. The seeds are reddish brown in color, spherical, 
and number 15 to 25 in each silique. 

GeographicaL — ^The turnip seems to have originated in Europe or Western 
Asia. By cultivation, it has spread into all temperate regions. The cul- 
tivated sorts are grown as cool-season crops. 

Types of Turnips. — There are numerous varieties of turnips, 
varying chiefly as to shape and color of "root'' (Fig. 140). 



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338 BOTANY OF CROP PLANTS 

develop the sweetness and flavors for which they are so well 
known only in the Northern States where the nights are cool. 

BRASSICA NAPUS (Rape) 

Description. — Rape is a biennial plant, growing to a 
height of 2 to 3 feet. It thrives best in those regions with 
cool summers. The stem is branched to a considerable 




Fig. 142. — Rutabaga (Brassica campestris). 



extent. There is no swollen root. The lower leaves are 
lyrate, the upper ones oval to lanceolate and clasping the 
stem. The inflorescence is of the typical racemose type. 
The flowers are bright yellow. The seeds are black or dark 
purple. The seedlings and yoimg plants resemble those of 
B. campestris (rutabaga). 

Varieties and Uses. — The principal variety of rape in the 
United States is Dwarf Essex or English rape. This is a 



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CRUCIFERiE 339 

variety used for its green foliage, and hence is treated as an 
annual. This type of rape is used as a fall pasture for sheep, 
pigs or cows, as a green manure, and as a soiling crop, catch 
crop, or cleaning crop. ''Rape cake,'' made from the seeds 
by expressing the oil, is used as a stock food, and the oil 
itself is of some value. About 42 per cent, of the seed is 
composed of rape oil. 

BRASSICA NIGRA (Black or Brown Mustard) 

Description. — The black mustard is an annual herb 2 to 
7 feet tall, and freely branching. The lower leaves are hairy 
and deeply pinnatifid, with one large, terminal lobe and 
two to four smaller, lateral ones; the lobes are coarsely 
toothed. The upper leaves have much shorter petioles than 
the lower, or they are entirely sessile, and the blades are 
entire and oblong or lanceolate. The flowers are bright yel- 
low. The pods are slender, four-sided, oppressed against the 
stem, and measure about }i inch or more in length. The 
seeds are dark brown. 

Black mustard is a native of Europe and Asia. It has 
become naturalized in this country and has escaped from 
cultivation, becoming frequently a troublesome weed. 

Black mustard resembles charlock (Brassica arvensis)^ 
one of the worst pests in grain fields of the Middle West. 
Charlock has long, knotted pods with stout beaks, while the 
pods of black mustard are short, four-angled, and with short 
beaks. The pods of white mustard are somewhat bristly. 
Charlock, black mustard and white mustard are propagated 
by seeds. In their eradication, no attention needs to be 
directed toward the starving out of rootstocks, which are so 
typical of perennial weeds. Every effort is made to prevent 
them from going to seed. Much success has attended the 
use of chemical herbicides, chiefly iron sulfate, in eradicating 



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340 BOTANY OF CROP PLANTS 

the mustards from grain fields. All grasses are resistant to 
injury from this spray, but the young mustards, and many 
other weeds, are quite easily killed by it. This is due to the 
fact that the spray does not adhere so readily to the smooth 
grass leaves as to the mustard leaves; moreover, although the 
tips of grass leaves are injured, the growing tissue at the leaf 
base may not be touched by the spray, and hence the recovery 
is rapid. 

Related Species. — It is closely related to the white mustard which is de- 
scribed hereinafter, and to Chinese or Indian mustard (Brassicajuticea), The 
latter is adventive from Asia in this country, often a bad weed, and sometimes 
its leaves are used for "greens." In the Indian mustard, the pods are i to 2 
inches long, and some of the forms have leaves twice the size of those in the 
ordinary black or white mustards. The Japanese or pot-herb mustard 
{Brassica japonica) is introduced into the United States. It has thin, soft 
leaves which are valued as "greens." 

Uses.— The plant is used mainly for garnishing, also in 
salads and in the preparation of meat dressmgs and sauces. 
Occasionally it is boiled like spinach. Table mustard is the 
ground seeds of black mustard. The aroma and pungency 
of mixed mustard (table mustard) does not exist in the seed 
itself, but is given rise to when the groimd seed is mixed with 
water. This pungent, volatile oil is an allylthiocyanate and 
is formed by the action of a specific enzyme, myrosin, upon 
potassium myronate — a glucoside present in the seed. 

BRASSICA ALBA (White Mustard) 

This species has characteristics very similar to those of 
black mustard. It is distinguished from the latter chiefly by 
its lighter colored bristly pods, and its lighter colored and 
larger seeds. 

The plant is a native of Europe, Asia and northern Africa. 
It is used similarly to the black mustard, and in addition is 



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CRUCIFER.E 341 

sometimes used as a green manure. The mixed mustard 
from this species is less pungent than that from B, nigra. 

RAPHANUS SATIVUS (Garden Radish) 

Habit — The common garden radish is an annual or bien- 
nial herb. It may produce fruit the same year, when planted 
early in the season, while, if planted late, it produces a 
fleshy tap root the first year, which may be kept over the 
winter imtil the next year, when it produces fruit. 

Root. — The radish vegetable is mainly a tap root, varying 
in size, shape, and color. At the top is a short hypocotyl 
(stem). The laterals from the tap root are few in number 
and very slender. 

Stem. — From the hypocotyl or crown of the radish, there 
first appears a rosette of leaves, and later an erect, freely 
branching stem, i to 2 J^ feet tall. This stem may be sparsely 
pubescent with stiff hairs, especially below, or rarely gla- 
brous throughout. 

Leaves. — The basal and lower leaves are deeply lyrate-pin- 
natifid, 4 to 8 inches long; the upper leaves are few, small, 
and oblong. 

Inflorescence and Flowers. — The inflorescence is an elon- 
gated raceme (Fig. 132). The flowers are of the typical mus- 
tard type; the sepals are erect and sac-Kke at the base; the 
petals rose-lilac or white. 

Fruit. — The pods are i to i3^ inches long, two- to three- 
seeded, fleshy, or corky with a spongy tissue separating the 
seeds; the pods are not longitudinally grooved or promi- 
nently constricted; they are capped by a long conic beak 
which may equal or exceed the pod itself. 

Seeds and Seedling. — The seeds are small and of a yellowish 
color; on one side, when viewed with a hand lens, may be 
seen a small spot, in reality double, made up of the hilum and 



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342 BOTANY OF CROP PLANTS 

micropyle. Endosperm is absent. The cotyledon leaves 
are persistent until the root becomes of considerable size and 
may be seen at the crown of the radish, lying flat against 
the root. Each cotyledon leaf is oblong in outline and 
broadly notched at the tip. 

Geographical Distribution and Origin. — The common 
radish is foimd growing wild in the temperate regions of the 
Old World. It was introduced into this country by the 
earUer settlers and here, as wherever it is planted, has 
escaped from gardens, becoming in many instances a rather 
common wayside plant. Radishes that run wild in this 
manner produce a root that is slender and woody, possibly 
reverting to the type from which it came. E. A. Carriere 
held the opinion that our common garden radish has spnmg 
from Raphanus raphanistrum, the wild radish or white 
charlock, and a common weed throughout Europe, and also 
adventive in the United States. He bases his opinion on his 
own experiments which in brief were as follows: The seeds of 
Raphanus raphanistrum, which has very woody and slender 
roots, were planted and after five years of care there was 
developed a type of root which was fleshy, large, and varying 
in form and color. The roots developed had the flavor of our 
garden radishes and were edible. In spite of the experiments 
of Carriere, many botanists believe that white charlock is not 
the projenitor of the radish. For example, it is known that 
the garden radish long ago was a common plant in India, 
China, and Japan. But Raphanus raphanistrum is not 
found in these countries, and furthermore, the main move- 
ment of ^cultivated plants has not been from Europe to Asia, 
but from the orient to the Occident. The true history of the 
radish seems to be unknown. 

Closely Related Species. — Raphanus raphanistrum, white charlock, men- 
tioned above, may be quite easily mistaken for the common radish, especially 



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CRUCIFEILS: 343 

when the latter has run wild. White charlock, however, has yellowish 
flowers turning white or purplish, and a silique which is much more conspicu- 
ously jointed and longitudinally grooved than that of common radish. 

Raphanus sativus caudatus, the rat-tailed radish, an annual herb native to 
South Asia, has a slender, twisted pod, 8 to lo inches long, which thus differs 
from the short, thick ones of common radish. These pods form the edible 
portion of the plant. 

Tjrpies of Radishes. — As to seasonal development, there are 
three groups of radishes, as follows: 

1. Early or Forcing Radishes, — ^A forcing crop is one grown 
out of season, and out of its natural environment. Hot 
beds, cold frames and greenhouses are the forcing structures 
in use. The chief crops forced besides radishes are lettuce, 
tomatoes, cucumbers, cauliflowers and beans. Early or 
forcing radishes reach an edible size very soon, often in from 
twenty to thirty days. In this group, belong such varieties 
as French Breakfast, Early Scarlet Turnip, Scarlet Globe, 
Long Scarlet Short Top, and White "Icicle." 

2. Summer Radishes, — The roots of this group are slower in 
maturing, requiring from six to eight weeks to reach a 
marketable size, and are larger than those of the first group. 
Here belong such varieties as Long White Vienna, Ghartiers, 
White Strasburg, Stuttgart. 

3. Winter Radishes, — These have a compact and firm flesh 
and keep well through the winter. The roots require several 
months to reach maturity, often attaining a large size. 
Gommon winter varieties are Black Spanish, Sakurajima or 
Japanese radish, and White Ghinese. 

As to shape, radishes may be classified as follows (Fig. 143): 

1. Round or turnip-shaped (Early Scarlet Turnip, Scarlet Globe, Scarlet 
Gem). 

2. Olive or oval-shaped (intermediates) (French Breakfast, Early Scarlet 
Olive-shaped, Black Spanish). 

3. Half-long (Scarlet Half -long, French, Half-long Deep Scarlet). 

4. Long (Vienna, Chartier, Long Scarlet, White " Icicle ")• 



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BOTANY OF CROP PLANTS 



Radishes vary in color: some varieties are white, otiiers pink, red, purple, 
mottied, or black, or red, tipped with white, etc. 

RADICULA (Water Cress and Horse-radish) 

Members of this genus are branching herbs with simple or 
•pinnate lobed, dissected, or rarely, entire leaves. Flowers are 




Fig. 143. — Types of radishes (Raphanus sativus). A, turnip-shaped; JB. 
globular; C, olive-shaped; D, half -long; E, long. {After CorbeU.) 



in elongated racemes; they have spreading sepals, yellow or 
white petals, and one to six stamens. The siliques are short or 
elongated, pencil-shaped, without a stalk or stipe, with one- 
nerved valves; there are numerous turgid seeds in two rows in 
each cell, or very rarely one row in each cell. 



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CRUCIFERiE 345 

The genus is one of wide distribution; it is most abundant 
in the north temperate zone. 

There is a rather large number of species, some of which are 
amphibious, others aquatic. The two principal economic 
species are Radictda armoracia (horse-radish) and Radicula 
nasturtium-aquaticum (water cress). The former is terrestrial, 
the latter aquatic. 

RADICULA ARMORACIA 
(Horse-radish) (Fig. 144)] 

Description. — Horse-radish is a hardy perennial from a 
white, fleshy, cylindrical root which branches at the lower 
end. The fibrous roots may penetrate to a depth of 6 or 7 
feet. In propagating the plant, the slender side roots usually 
are used; pieces of the main root are also used for this purpose. 
The plants are 2 to 3 feet tall, branching, with long-petioled, 
oblong, basal leaves, 6 to 12 inches long, that have crenate, 
sinuate or pinnatifid margins. The upper leaves are smaller, 
sessile, oblong, or lanceolate. The racemes are terminal or 
axillary, and bear white flowers. The pods are oblong or 
nearly globose and bear a short persistent style. In cultiva- 
tion, the plant seldom produces seed, but is propagated by 
root cuttings. 

GeographicaL — Horse-radish is a native of Europe. It is a common home 
garden plant in the United States, and in some instances has escaped from 
cultivation and become a troublesome weed. 

Uses. — ^The root is grated or scraped, sometimes mixed 
with vinegar, and used as a condiment. 

RADICULA NASTURTIUM-AQUATICUM 
(Water Cress) 

Description. — This is a perennial, aquatic plant with long 
floating or creeping stems which readily take root at the 



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346 BOTANY OF CROP PLANTS 

nodes. The leaves are compound and odd-pinnate (Fig. 
145); the terminal segment is larger than the laterals, all of 



Fig. 144. — Horse-radish (Radicula armoracia). A, basal leaf; B, fruit; C, 
cauline leaves and inflorescence. 



which are slightly wavy on the margin and of a dark green 
color. The white flowers are in terminal racemes; the petals 
are twice as long as the sepals. The siliques (Fig. 145) are 



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CRUCIFERiE 347 



slightly curved, on pedicels 
of equal length, and bear 
a few seeds in two rows. 

Geographical. — Water cress is 
a native of Europe an4 Northern 
Asia, but has become naturalized 
in both North and South Amer- 
ica. It is widespread in North 
America. 



References 

Carriere, E. a.: Une nouvelle 
plante fourragere et econom- 
ique. Journ. d*Agric. Prat. 
Annee, 33, tome 11: 845-847, 
1869. 

GoFF, E. S.: Vegetables: Turnip- 
6th Ann. Rept. N. Y. Agr. 
Exp. Sta., 168-190, 1887. 

Henslow, G.: The History of 
the Cabbage Tribe. Jour. 
Roy. Hort. Soc. (London), 
34: 15-23, 1908-1909. 

Shaw, T.: The Rape Plant: Its 
History, Culture, and Uses. 
U. S. Dept. Agr. Farmers' 
Bull. 11: 1-20, 1893. 



Fig. 145. — Water cress (Radicula nas- 
turtium-aquaticum) . 



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CHAPTER XXVI 

ROSACEiE (Rose Family) 

The Rosaceae are well represented in North Temperate 
climates. There are about 1,200 species within 65 genera. 
The most important genera from the crop standpoint are 
Rubus (raspberry, blackberry and dewberry), and Fragaria 
(strawberry). Other genera of importance or of interest are 
Spircea, an ornamental shrub, Potentilla (five-finger or cinque- 
foil), Cercocarpus (moimtain mahogany), and Rosa (rose). 

Leaves. — ^The leaves are alternate, either simple (as in 
some Rubus species), or compound (strawberry, rose). 
There are two rather prominent stipules, free from or adher- 
ent to the petiole. 

Inflorescence. — There are several different kinds of flower 

clusters in the family. It is a terminal corymb (flat-topped 

raceme) in Opulaster, either racemose, 

cymose, corymbose or paniculate in Spircea, 

terminal or axillary and solitary, racemose 

or paniculate in Rubus, and corymbose or 

racemose in the strawberry. It is interest- 

FiG. i46^piorai ^S to note the great number of different 

diagram of Rubus., gorts of infloresccnces in this one family, and 

(After Wosstdlo.) "^ ' 

contrast it with the mustard family, in which 
the raceme is the one prevailing type, or with the carrot 
family in which the umbel is, with the exception of one 
genus, the only type, or with the sunflower family, all mem- 
bers of which have a head inflorescence. 

Flowers. — The flowers (Fig. 146) are regular, and usually 
perfect. In some cultivated strawberries imperfect flowers 

348 




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ROSACEA 349 

are borne. The calyx is free from or grown to the ovary, 
five-lobed, and sometimes subtended by a set of bracts 
(epicalyx, as in strawberry). The petals are distinct, as 
many as the lobes of the calyx and inserted on the margin of 



Fig. 147. — American red raspberry (Rubus strigosus) . A , median lengthwise 
section of flower, X 4; B, same of frmt, X 4; C, single immature pistil, X 5. 

the disk (Fig. 147). This disk is an outgrowth of the recep- 
tacle and forms a flat rim about the calyx base. In cultivated 
roses there are numerous petals which have developed from 
primordia that normally become stamens. This bears out the 



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3 so BOTANY OF CROP PLANTS 

belief that stamens are leaves, morphologically. The pro- 
duction of supernumerary petals is known as "doubling." 
The stamens are numerous, distinct, and attached to the 
margin of the toral disk (Fig. 147). The anthers are small 
and two-celled. The carpels are usually numerous and dis- 
tinct, or rarely attached to the calyx. The ovary is one-celled 
(rarely imperfectly two-celled) with a terminal or lateral style, 
and with from one to many ovules. 

Fruit. — The fruit is a follicle in Spircea, an aggregate of 
drupelets in raspberry, blackberry and dewberry, or an 
aggregate of achenes in strawberry and rose. The follicle 
is a pod-like fruit, with one carpel, which opens along one 
side only and usually bears numerous seeds. The true pod, 
characteristic of the pea family, is a one-carpelled fruit, 
which splits along two sides. It will be remembered that 
the capsule has several carpels. A drupelet is a small 
drupe — a one-seeded fruit with a fleshy mesocarp and stony 
endocarp. 

Key to Important Genera op RosACEiE 

Fruit not inclosed in a hollow receptacle, i.e., the caljrx not constricted over 
the fruit. 
Carpels becoming follicles, SpircRa. 
Carpels become smaU drupelets crowded on a fleshy receptacle, Rubus 

(raspberry, blackberry, dewberry). 
Carpels becoming dry achenes. 
Style becoming long and plumose, Cercocarpus (mountain mahogany). 
Style short. 
Receptacle fleshy in fruit, Fragaria (strawberry). 
Receptacle not fleshy in fruit, PoteniiUa (five-finger or cinque-foil). 
Fruit inclosed in a hollow receptacle, i.e., the calyx constricted over the 
fruit, Rosa (rose). 

RUBUS (Raspberry, Blackberry, Dewberry) 

Stems. — The plants of this genus are usually shrubs, 
rarely herbs {Rubus Chamcemorus, cloudberry, knotberry or 



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ROSACEA 351 

mountain bramble). They are usually designated as 
"brambles.'' The stems are, as a rule, prickly, erect, decum- 
bent, or creeping. The stems (" canes '0 commonly die after 
one or two years, new ones being sent up from the roots. The 
main growth of the stem is made during the first year, in 



Pig. 148.— Fruiting branch of American red raspberry (Rubus strigosus). 

most Rubi; side branches are produced the second year; the 
flowers and fruit are developed on these side branches. The 
entire cane usually becomes weak and dies after^fruiting. 
This suggests the advisability of removing canes once they 
have borne fruit. 

Propagation. — Red raspberries, blackberries and dew- 
berries (rarely) "sucker'' readily. This natural tendency to 



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352 BOTANY OF CROP PLANTS • 

send up sprouts from the roots is taken advantage of by the 
fruit-raiser. All plants which reproduce naturally from 
suckers are easily propagated from root cuttings. Black- 
cap raspberries and dewberries produce stolons. A shoot 
bends over by its own weight and takes root at the. tip. 
When once the tip has rooted well, the shoot may be cut loose 
from the parent stem and such rooted tips used as "sets.'' 

Leaves. — These are alternate, simple, palmately lobed or 
compoimd three- to seven-foliate, and bear persistent 
stipules. In Rubus trivialis, southern dewberry, the leaves 
are evergreen. 

Inflorescence. — The flowers are terminal or axillary, soK- 
tary, in panicles or racemes. The flowers and fruit in all 
representatives of the genus Rubus are borne on shoots which 
arise from the growth of the year before. For example, in 
1913, a shoot (cane) is sent up from the root. This bears 
leaf buds entirely. In 1914, these lateral buds elongate, and 
some of the resulting shoots bear inflorescences. The 
shoots, developed in 1913, once having borne fruit in 1914, are 
no longer useful. The cutting out of these useless shoots will 
induce the development of new ones from the roots. 

Flowers. — The flowers (Fig. 147, A) are rather large, regu- 
lar, and usually perfect. In Rubus vUif alius ^ the Pacific Coast 
dewberry, however, there are both hermaphroditic and pistil- 
late plants. Rubus ChamcBtnorus is dioecious. The recep- 
tacle is flat or convex. The five-parted calyx is persistent 
in the fruit. There are five petals, which are usually white, 
and deciduous. The stamens are numerous, and attached 
at the base of the disk. The numerous pistils are separate 
and crowded on the receptacle; each pistil bears a single 
thread-like style. The styles are hairy and somewhat 
broadened at the base in the raspberry; while they are 
narrow and free from hair at the base in the blackberry. 



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ROSACEA 353 

Pollination. — ^As a rule, the anthers and stigmas mature 
simultaneously. There is abundant nectar secreted by a 
fleshy ring on the margin of the receptacle, inside of the 
stamens. Insects facilitate pollination. Better yields are 
secured, in the case of some dewberries, if they are planted 
adjacent to another variety so that cross-fertilization will 
result. 

Fruit. — The fruit (Fig. 147) of the genus is an aggregate. 
The numerous pistils ripen into drupelets which cling to- 
gether to a greater or less degree. In the dewberries and 
blackberries, the drupelets are firmly attached to the recep- 
tacle while in raspberries the drupelets readily separate from 
the receptacle when the fruit is being picked, clinging together 
in the form of a cup. The exposed surface and the angles 
between the faces of each drupelet are pubescent in the rasp- 
berry, and the faces themselves are glabrous. The sticking 
together of the drupelets is due to the interlocking of these 
crooked hairs. The blackberry and dewberry drupelets are 
glabrous throughout. 

Geographical. — ^The Rubi are of wide geographic distribution; the greater 
number of species, however, occurs in North Temperate regions. 

Classification. — The numerous members of the genus fall 
into three groups which may be distinguished as follows: 

Key to Groups of Genus Rubus 

Drupelets firmly attached to receptacle, not separating from the latter when 
fruit is being picked. 
Stems upright; plant propagating by suckers; lower, outer flowers open 

first. Blackberries. 
Stems trailing; plant propagating by tips; center flowers open first, DeTv- 
berries. 
Drupelets readily separating from the receptacle when fruit is being picked, 
clinging together in form of cup. Raspberries. 

23 



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354 BOTANY OF CROP PLANTS 

BLACKBERRIES 

Only those species are considered in the following keys 
which have yielded us our important fruit-bearing varieties. 
The key considers the groups of blackberries as given by 
L. H. Bailey m "The Evolution of Our Native Fruits." 

Key to Species of Blackberries 

Inflorescences conspicuously loose, the few flowers scattered on long pedi- 
cels, Rubus nigrobaccus X R. villosus (loose-cluster blackberries or black- 
berry-dewberry) . 

Inflorescences more compact, the flowers not so scattered along the main 



Inflorescences leafy, i.e., pedicels subtended by leaves, Rubus argutus 

(leafy-cluster blackberries). 
Inflorescences entirely or almost leafless. 
Clusters long. 
Berries black, R. nigrobaccus (common long-cluster or high-bush 

blackberry). 
Berries cream-colored or pink, R. nigrobaccus var. albinus (white 
blackberry). 
Clusters short. 
Lower surfaces of leaves white-pubescent; plants i to 3 feet tall, very 

thorny, R. cuneifolius (sand blackberry). 
Lower surfaces of leaves pubescent but not whitish; plants i to 8 feet 
tall, thorny, R, nigrobaccus va,T.sativus (short-cluster blackberries) . 

Rubus nigrobacctts. — ^The tall stems are furnished with strong, hooked 
prickles. The long-stalked leaves have ovate and distinctly pointed leaflets. 
Inflorescences are long, glandular-hairy racemes with large, showy flowers on 
pedicels that stand out almost at right angles. The fruit is firm, oblong, 
sweet, and aromatic. 

The plant is found throughout eastern United States and northward into 
Canada. The variety Taylor is the best known. Snyder and Kittatinny 
are common varieties of the short-cluster blackberries. The white blackberry 
has greenish-yellow stems and cream-white fruits, and occasionally grows 
wild. 

Rubus nigrobaccus X R* villosus. — ^The loose-cluster blackberries are con- 
sidered to be hybrids between the high-bush or long-cluster blackberry and 
the northern dewberry. The plants are rather low and spreading and have 
characteristic, broad, jagged leaflets. 



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ROSACEA 355 

The fruits are small and globular or globular-oblong, and grow m small 
clusters. Wilson and Rathbun are typical varieties. 

Rubus argutus. — ^The plants are erect, stiff, prickly, and with stems 
strongly angled, almost grooved. The small leaflets are firm and rather rigid, 
and coarsely toothed. Inflorescences are short and leafy. The fruit is small, 
globular, and black. The species is found growing wild from New England 
to Florida and Arkansas. Common varieties are Dorchester, Early Harvest, 
and Brunton Early. 

Rubus cuneifolius.— The sand blackberry is a stiff, thorny plant about 
3 feet tall. The leaflets are thick, obovate, and white-pubescent beneath. 
Inflorescences are short and bear but a few (two to eight) flowers. The fruit 
is of medium size, sweet, and desirable. This species grows wild from south- 
ern New York and Pennsylvania to Florida, Louisiana and Missouri. Topsy 
is the common cultivated variety; it often does not have the pubescence of 
the species. 



Fig. 149. — Northern dewberry (Rubus villosus). 

DEWBERRIES 

These differ from blackberries in their traihng habit, 
cymose inflorescences, and propagation by tips. They 
have received the name ^'traihng blackberry.'* There are 



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3S6 BOTANY OF CROP PLANTS 

four principal groups of dewberries, which are distinguished 
in the following key: . 



Key to Principal Species of Dewbeiuoes 

Leaves'evergreen, R. trivialis (southern dewberry). 
Leaves deciduous. 

Buds tipped by the united ends of the sepals, forming a spine; flower clus- 
ters forking into two or three parts, R. invisus (northern dewberry). 
Buds not tipped by the united ends of the sepals to form a spine. 
Both hermaphrodite and pistillate plants; leaflets coarsely toothed, R, 

vUifoUus (western dewberry). 
Plants all perfect; leaflets finely toothed, R. villosus (northern dewberry). 

Rubus trivialis. — ^These are trailing shrubs, with stout, hooked prickles and 
bristles on the stems, and with upright branches 3 to 9 inches tall. The leaves 
are trifoliate, petioled, and with oval, leathery, serrate, evergreen leaflets. 
The inflorescences are one- to five-flowered. The flowers are large, white, 
and have petals that are much longer than the sepals. The fruit is black, 
and up to i inch long. The species occurs from Virginia to Florida and west- 
ward to Texas and Missouri. The best-known horticultural variety is 
Manatee. 

Rubua invisus. — ^The stems are moderately prickly. The leaflets are large 
and coarsely and simply dentate. The erect peduncles are elongated. The 
large flowers are on long pedicels; flower buds are tipped by the united ends 
of the sepals. The species is reported by Bailey as growing wild from New 
York to Alabama and east to Kansas and Missouri. The chief varieties are 
Bartel and Mammoth. 

Rubus vitifolius. — ^This species occurs in California, Oregon, Washington 
and Idaho. Skagit Chief is the principal form in cultivation. 

Rubus villosus. — The plants are robust, with smooth stems and large, 
thick leaves, which have three to seven oval or ovate, long-pointed and sharply 
double-toothed leaflets. The inflorescences are one to three-flowered, leafy, 
and cymose. The fruit is globular, and has a few, shining-black, and sweet 
drupelets. This is the common dewberry of the Northern States; it b found 
growing wild from Newfoundland to Virgina and westward to Minnesota and 
Kansas. Windom, Geer and Lucretia's Sister are varieties. The Lucretia 
dewberry (variety rorihaccus) is a more robust form with large wedge-obovate, 
jagged leaflets, and large flowers on long pedicels. 



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ROSACEA 357 

RASPBERRIES 

There are four well-known groups of cultivated rasp- 
berries: black-cap, purple-cane, American red, and European 
red. 

Key to Principal Species op Raspberries 

Fruit purple-black, rarely yellow; propagating by tips, R, occtdetUalis 

(black-cap). 
Fruit purple, dark red, light red, or sometimes yellow; propagating by tips 
or suckers. 
Stems stifE and erect; fruit produced more or less continuously throughout 

the season, R. idiBus (European red). 
Stems more slender and drooping; fruit produced less continuously through- 
out the season. 
Stems bristly, not glaucous; fruit light red; inflorescence racemose, R. 

strigosus (American red). 
Stems prickly, slightly glaucous; fruit dark red; inflorescence racemose- 
cymose, R. strigosus X R- occidentalis (purple-cane). 

Rubus occidentalis. — The slender stems are often lo to 12 feet long, rooting 
at the tip, sparingly supplied with small hooked prickles, and sometimes glan- 
dular-bristly above. The leaves are trifoliate, stipulate, with oval or acumi- 
nate, toothed leaflets, that are white-hairy on the under side. The inflor- 
escences are dense, and corymbose. The flowers are on short pedicels; the 
petals are shorter than the sepals. The black-cap raspberries are the most 
important in this country. The species is found throughout eastern United 
States, northward into Quebec and Ontario, and westward to Oregon and 
British Columbia. 

Some of the western forms have been given distinct specific names (R. leu- 
codermiSy R. glaucifolius, R. bernardinus. 

Rubus idfleus. — ^The stems are stiff and erect, and furnished with prickles; 
glandular bristles are never present except in some cultivated forms which 
may be considered as hybrids between R. idaus and R. strigosus; pubescence 
occurs on peduncles, pedicels, petioles are nearly always flattened and slightly 
curved. The thick leaves are white-downy beneath. The fruit is purple or 
yellow and is produced throughout the season. The European raspberry is 
not cultivated to any extent in this country at the present time. It is a native 
of Europe and Asia. 

Rubus strigosus. — ^The stems are slender and bear stiff, straight or hooked 
prickles; glandular bristles occur on peduncles, pedicels, petioles, and calyx. 
The leaves are three- to five-foliate, with ovate or oblong-ovate, sharply serrate 



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3S8 BOTANY OF CROP PLANTS 

or lobed leaflets, which are whitish-pubescent beneath. Tlie inflorescences 
are terminal or axillary, and racemose; the flowers are white. The fruit is 
light red, rarely yellow, and is not produced continuously throughout the 
season. Rubus strigosus is the native, common red raspberry. It is dis- 
tributed from North Carolina to New Mexico, northward in the Rocky 
Mountains to Manitoba and British Columbia and eastward to Newfound- 
land and Labrador. Cuthbert is one of the principal varieties. 

Rubus strigosus X R. occidentalis (R. neglectus). — The stems are long and 
often rooting at the tip, glaucous, prickly, and bristly. The inflorescence is 
racemose-cymose and has short, erect or ascending peduncles. The fruit 
varies in color from purple-black to bright purple, and sometimes yellow. 
Shaffer and Columbian are the chief varieties. 

The Loganbeny. — ^This is a rather notorious fruit that has resulted from 
crossing a blackberry and a raspberry. It is supposed that the blackberry 
was the variety Aughinbaugh and the raspberry, Red Antwerp. Aughin- 
baugh is a pistillate variety of R. vitifolius. Evidence^ has recently been 
presented tending to show that the loganberry has behaved as a true species, 
and is not a hybrid. The loganberries are large, often i to i J^ inches long, 
and of a rich, dark red color, but unfortunately not of very superior flavor. 

Mayberry. — This is supposed to be a cross between a Japanese species, 
Rubus micro phyllus and Cuthbert, a variety of Rubus strigosus. 



FRAGARIA (Strawberry) 

Roots and Steins. — Strawberries are low, perennial plants 
with very short, thick stems set close to the surface of the 
ground. Such very short-stemmed plants are usually 
termed "acaulescent." The branches that arise from the 
axils of the closely set leaves are called ^^ runner s,^^ Runners 
are slender stems, growing along the ground surface; they 
have long intemodes, and produce leaves and flowers and 
roots at the^nodes. Runners are used as a means of propa- 
gating the plant. They are attached to the old plant for 
but one season. In the Virginian group of strawberries, the 
runners start to form as early as new leaves are produced and 
may attain a considerable length before the fruit is mature. 
In the Chilean group, the runners are usually formed after 

1 Journal of Heredity, 7: 504-507, 1916. 



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ROSACEA 359 

the fruit is matured. Runners may branch. New branches 
from the main perennial stem appear, of course, above the 
old ones, hence there is a tendency for the short stem to 
become more and more exposed above the groimd surface. 
Roots do not extend over a depth of 2 feet in the soil, and 
horizontally, scarcely beyond the area covered by the leaves. 
Practically all roots are within the first foot of soil. 



Fig. 150. — Flowers of strawberry (Pragaria chiloensis). Above, two perfect 
flowers; below two pistillate flowers. 

Leaves. — The leaves are alternate and arise in a tuft; the 
petioles are usually much longer than the leaf blades, which 
are divided into three leaflets (trifoliate); sheathing, mem- 
branous, adnate stipules which increase in size as the leaf 
grows, occur at the base of the petiole. 

Inflorescence and Flowers. — The white flowers are in 
small racemes or corymbs on long, erect, leafless scapes 



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BOTANY OF CROP PLANTS 



which spring from the crown of the plant. The flowers are 
usually perfect; however, there are some varieties (Bisel, 
Princess, Warfield, etc.) which have only pistillate flowers 
(Fig. isq); there are no commercial varieties that have only 
staminate flowers. In planting varieties with pistillate 
flowers only, it is necessary to have rows near-by planted to 
pollen-bearing individuals. Some perfect-flowered varieties 




peial 

achene 
calux lobe 



N 



\^Yinm of receptacle 
^fleskj recepiack 



Fig. 151.- 



-Strawberry (Fragaria chiloensis). 
flower. X 4. 



Median lengthwise section of 



(Glen Mary and Crescent) bear very few stamens, and hence 
are practically self-sterile. The receptacle is convex or con- 
ical (Fig. 151). The calyx is five-parted, with five bracteoles 
(epicalyx) below, that ^are persistent in the fruit. There 
are five obovate, short-clawed petals, attached to the rim of 



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ROSACEiE 361 

the receptacle. There are numerous stamens, as a rule, 
sometimes a few or none; they are attached to the rim of the 
receptacle, persistent in the fruit, and possess slender fila- 
ments and small anthers. Pistils are numerous on the 
smooth, convex, or conical receptacle which becomes modi- 
fied in the fruit (Fig. 152, A). Each carpel bears a style 
laterally placed (Fig. 152, B), and a single ovule. 

Fertilization, and Development of the Fruit. — Strawberries 
are protogynous, that is, the pistils of a flower mature before 
its stamens. Hence cross-fertilization is secured; and this 
usually by insects. Non-fertilization or incomplete fertiU- 
zation is usually indicated by berries with hard, greenish, 
undeveloped apices, so-called '^ nubbins." The true fruits 
of a strawberry are the achenes (so-called *' seeds '0 scattered 
over the fleshy receptacle. Unless the ovules are fertilized, 
the receptacle does not mature properly. This behavior is 
the rule in most plants. When a sperm nucleus of the pollen 
tube unites with the egg nucleus of the ovule, resulting in 
fertilization, there is set into action a train of changes which 
not only involve the ovule itself, but which extend to the 
ovary wall, and, as in the strawberry, to the receptacle. 
Undoubtedly, the stimuli are chemical in nature, but just 
what they are and how they act is not known. 

The Mature Fruit. — The strawberry "fruit'' (popularly 
speaking) is an aggregate of true fruits. The fleshy part 
of the "fruit" is receptacle, while the true fruits (botanically 
speaking) are achenes partially imbedded in the surface of 
the receptacle. In a lengthwise section (Fig. 152, A) of the 
ripened fruit, the receptacle is seen to be composed of a 
fleshy pith and cortex with fibro-vascular bundles between 
them. It is in reality stem structure. These bundles send 
off side branches into the cortex, and some of them extend 
to the achenes. The persistent calyx and epicalyx, and 



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362 



BOTANY OF CROP PLANTS 



withered stamens are at the base of the fruit. These con- 
stitute the "Aw//'' of the fruit. The achenes are attached to 
the receptacle a short distance above their base and the 
styles arise from the ventral side, a little above the point of 




Fig. 152. — Strawberry (Fragaria chiloensis). A^ "fruit" in median length- 
wise section, X 2>4; 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. 



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ROSACEA 363 

Principal Fruit-bearing Species. — The 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 calif ornica 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 Fragasia 

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; cdHiyx 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 



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CHAPTER XXVII 
POMACES (Apple Family) 

Habit| Leaves. — Members of the apple family are either 
trees or shrubs. The alternate simple or compoimd leaves 
are petioled, and have small deciduous stipules. 

Inflorescence. — The inflorescences are racemose {Amel- 
anchier, service-berry), cymose {Mains, apple, Sorbus, moun- 
tain ash) or simple (Cotoneaskr, evergreen or fire thorn). 

Flowiers. — 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- 
^us 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 Amelanchiery one to five in Cratcegus (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 



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POMACES 367 

Geograpliical. — ^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 Pomaces 

Ripe carpels bony, Cratagus (thorn-apple, haw, hawthorn). 
Ripe carpels papery or leathery. 
Leaves compound, Sorbus (mountain ash). 
Leaves simple. 

Ovules one in each cavity, Amelanchier (service-berry, June-berry). 
Ovules (usually) two in each cavity. 
Flesh of the pome with grit-cells, Pyrus (pear). * 
Flesh of the pome without grit-cells, Malus (apples arid 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 ''spurs'^ 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- 



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368 BOTANY OF CROP PLANTS 

more that the fruit spur must be two or more years old before 
it will bear fruit. Paddock and Whipple ("Fruit Growing in 



Pig. 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 



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POMACEiE 



369 



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, Striped, Trans- 
cendent and Winesap are among those varieties 
producing fruit in the axils of leaves. Astra- 
chan, Ben Davis, Grimes, Hyslop, Jonathan, 
Mcintosh, 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 
yotmg 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.) 



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370 BOTANY OF CROP PLANTS 

conditions, the fruit and leaf buds are diflferentiated 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, cjone, 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 
Ejraus. A longitudinal section (Fig. 155) of a growing axis 
shows a number of bracts and bud scales siu'rounding 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 



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POMACEiE 



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. 156). 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. 



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372 



BOTANY OF CROP PLANTS 



Pollination and Fertilization. — The literature on this 
subject is extensive. Cross-pollination 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. 




Pig. 156. — Ploral 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 



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POMACEiE 



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 




nm oj recef\ac\e^^ 



Fig. 157. — Apple (Malus sylvestris). Median longitudinal section of 

flower. 

impresses its characteristics upon the fruit. It is difl&cult 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. 



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374 BOTANY OF CROP PLANTS 

Parfhenocarpy. — ^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 fertilized. However, develop- 
ment of the ovary does sometimes occur although fertiliza- 
tion fails. Such an imusual development of carpels is called 
parthenocarpy. This phenomenon is not imknown in the 
apple. With certain sorts of both apples and pears, fruits 
weighing loo grams have been developed without fertiliza- 
tion. Of course, parthenocarpic fruit is seedless. There are 
among cultivated plants many which bear seedless fruit. 
We noted that in the conmion Mission figs the fruit matures 
normally without fertilization of the ovules. Seedless to- 
matoes, egg plants, English forcing cucumbers, oranges, 
grapes, and bananas are quite common. 

Tlie Emit and Its 'Developmeat— Morphology, — There 
are two conmion opinions as to the nature of pomaceous 
fruits: 

1. Flesh is thickened calyiL 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. 
I SS)) 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 



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POMACEiE 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 line. 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 shght 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 lamellae. 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. 



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376 



BOTANY OF CROP PLANTS 




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POMACES 377 

Cross-section of Fruit. — In a median cross-section of the 
apple fniit (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 reaUty stem, surroimds 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 bimdles 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 Une, 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 line, 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. In judging form, the apple is held so^^as^to 



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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 roimd, 
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 hasal^ situated near the base of the 
cal)^ tube; median, near the middle; or marginal, near the 
outer edge. The calyx tube itself varies in shape from con- 
ical to fimnel-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. 



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POMACES 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, Malus floribunda (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 baccata 
(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 J^ inches in diameter. 
Pedicels slender, i to ij^ inches long, Malus ioensis (Western crab- 
apple). 
Pedicels stout, J^ to i inch long, Malus soulardii (Soulard crab- 
apple). 
Leaves rounded or subcordate at base; pomes large, 2 to 4 inches in 
diameter Malus sylvestris (common apple). 

Malus floribunda, Flowering Crab. — ^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 J^ to % 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. 
sylvestris. 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. corcMiaiia, 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^ inches 
in diameter, somewhat flattened endwise, greenish-yellow, waxy, fragrant, and 



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38o 



BOTANY or 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. angustif olia) ; £, 
Soulard crab (M. soulardi); F, common apple (Wealthy) (M. sylvestris); G, 
American crab (M. coronaria); H, Siberian crab (M. baccata). X M. 



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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 various 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 
Mollis ioensis. 

M. soulardii, Soulard Crab. — ^This is a natural hybrid between the common 
apple (JIf . sylvestris) and the Western crab-apple (M. ioensis). It is a small, 
stout tree, with leavci similar to those of M. ioensisy in close clusters on short, 
densely woolly pedicels; the fruit is larger and of better flavor than that of M. 
icmsis. It grows wild in the Mississippi Valley. 

M. sylvestris, Conmum 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 (Malus 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- 



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382 



BOTANY OF 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 smnmer 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: 



Summer varieties 
Autumn varieties 
Winter varieties. . 
Crab-apples 



specific 
gravity 



1.049 
I 054 
1.056 
1.062 



Total 
solids 



Total 
sugar 



Invert 
sugar 



I 



12.33 
13.76 
14.29 
15.69 



9-53 
10.66 

11.43 
II. 71 



5.85 
6.93 
7.04 
8.08 



Cane 
sugar 



350 
3-53 
4.16 

3.45 



Acids a« 
HsS04 



0.33 
0.36 
0.41 
0.50 



Tannin 



0.040 
0.069 
0.050 
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- 



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POMACES 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 fermentation. 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 alcoholic 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 sKghtly, 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. 



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384 BOTANY OF CROP PLANTS 

Production of Apples in the United States. — In 1915 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, Pennsylvania, Illinois, Virginia, Kentucky, 
Indiana, Iowa and Michigan. 

PYRUS (Pear) 

The characters of this genus are very similar to those of 
Malus. The pears are trees or shrubs with simple leaves, 
and large flowers in terminal cymes, resembling those of the 




"pvenchuma cellt 



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. 160). 

The two most common species of Pyrus are Pyrus communis, 
the common pear, and Pyrus serotina 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-hke, the flowers appear before 
the leaves, and the calyx is deciduous. 



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POMACES 385 

PYRUS COMMUiaS (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. 

Fmit. — 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 
25 



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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 Jcommon 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-steriUty, that is, the inabiUty 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 coimtry 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 Kieffer. 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 

Kieflfer X Kieflfer i in 253 

Kieffer X Bartlett lin 5 

Kieffer X Le Conte i in 7 

Kieffer X Lawrence lin 6 

Kieffer X Duchess lin 5 

Kieffer X Anjou lin 4 

Kieffer X Clairgeau lin 3 

Kieffer X Garber lin 7 



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POMACES 387 

From these exp)eriments, Fletcher recommends (under 
Virgmia 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 effect 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 niunerous 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 quahty of the fruit. 

^ 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 stock 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. 



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388 BOTANY OF CROP PLANTS 

CYDONIA (Quince) 

The genus has much the same characters as Mains and 
Pyrus, except that each of the five carpels has several seeds, 
covered with a mucilagmous 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 15 
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 3^ inch long. 

Flowers. — ^As a rule, the flowers are solitary; the petals 
are white or light 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, 



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POMACES 389 

Cydonia vulgaris: Lusitanica, maliformis, pyriformis mar- 
morata, and pyramidalis. 

Uses. — Quinces are 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. Exp. 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, 191 5. 
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 Apple. Bull. Torrey 

Bot. Club, 44: 85-95, 1917- 
Chittenden, F. J. : Pollination in Orchards. III. Self-f ruitf ulness 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. 1 13-192 (Paris), 1875. 

Le jardin fruitier du museum, un iconographie de touts les especes et 
varietes d*arbres fruitiers cultives dans cet etablissement. Firmin 
Didot Freres. 
Drinkard, a. W. : Fruit-bud Formation and Development. Rept. Vic Agr. 

Exp. Sta., 1909-1910: 159-205, 191 1. 
EwERT, K.: Die Parthenokarpie der Obstbaume. Ber. Deut. Bot. Gesell., 

24: 414-416, 1906. 
Die Parthenocarpie der Obstbaume. Ber. Bot. Ges., 26: 414-416, 1906. 
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. Va. Agr. Exp. Sta., 

1909 and 1910: 213-224, 191 1. 
GoFF, E. S. : The Origin and Early Development of the Flowers in the Cherry, 

Plum, Apple and Pear. i6th Ann. Rept. Wis. Agr. Exp. Sta., 290-303, 

1899. 



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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. Card., 22: 330 and 
346-347, 1901. 
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.: Traits de la taille des arbres fruitiers, ed. 12, 123, 

Paris. 
Hedrick, V. P.: Dwarf Apples. N. Y. Agr. Exp. Sta. Bull. 406: 341-368, 

191S.. 
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. 

in. 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, 191 1. 
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, 191 3. 
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. 
WesTj^G. H.: The Pollination of Apples and Pears. Trans. Kans. State 

Hort. Soc, 32: 38-50, 1912. 



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CHAPTER XXVIII 
DRUPACEiB (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, 
amygdalin, 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 
soUtary (apricot), or in racemes (wild black cherry, etc.), 
umbels (sweet cherry, etc.), or cor3anbs (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, 
inB. 



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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. 




nm oj recepiacle 
\5t\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 



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DRUPACE^ 



393 



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 pisHlj 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. 

P>p of 
mrp 
mesocarp 
endocarp 

: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 yoimg ovary of a Prunus flower he will find 



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394 BOTANY OF CROP PLANTS 

two ovules; one of them aborts, the other devldops into a 
seed. The endosperm is absent, or presait only in a small 
amoimt. 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 
fpUo wing 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 



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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 line. 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 pliuns, 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, imlike those of the apple and 
j)ear, bear only flowers. They may 
break open before, simultaneously with, 
or after the leaf buds. The flowers are 
in fascicled lunbels. 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.) 



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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 orchards, 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 Pruntss species 
are insect-pollinated for the most part. 

Fruit. — ^After fertilization, 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 



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DRUPACEiE 397 

the stone ("pit") of the plum consists of hardened endocarp, 
seed coat, and embryo. The 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. triflora)^ 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. cerasifera. 
Flowers in threes, P. triflora. 
Flowers in clusters of three or more, rarely two, American Plums. 
Leaf serrations glandless, acute; calyx lobes entire, glabrous on the outer, 

pubescent on the inner surface, not glandular, P. americana. 
Leaf serrations glandular (at least when they first unfold), rounded or ob- 
tuse; calyx lobes glandular (except in P. angusHfoUd). 
Leaves broad, mostly oblong-ovate or obovate, the margin often doubly 
serrate; flowers 2 to 2.5 centimeters broad; calyx 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 IS 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. hortidana. 
Leaves usually thin, lustrous on upper surface, veins not conspicuous 
below, margin finely and evenly serrate. 
Leaves usually 6 to lo centimeters long; calyx lobes glandular, P. 

munsoniana. 
Leaves 2 to 6 centimeters long; calyx lobes glandless, P. angustifolia. 

•Adapted from The Plums of New York by Hedrick. 



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398 BOTANY OP 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 primes. The fruit is large, oval, usually com- 
pressed, blue or purple, and with a firm, greenish, yellow, or 
golden flesh, and free stone. Pnmes 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 pnmes, the 



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DRtrPACE^ 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 boiling water, glycerine or 
fruit juice. This gives the surface of the pnmes a shiny 
appearance, and also sterilizes the exterior. 

3. Peridrigon Plums. — This is a pnme 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 plmns, 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 pliuns. Lombard, Bradshaw, 
Victoria, Pond, and Duane are well-known varieties. 

Primus insititia. — ^This is a small tree not over 25 feet high 
with small 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 



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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. Bullaces. — This group contains a few varieties differing 
but little from the preceding group, except as to fruit shape. 
The Bullaces are spherical. 

3. Mirabelles, — These are roimd, yellowish or golden plums 
with a free stone and resemble much the green gages as to 
quality. 

4. St. Juliens. — This is a name applied to a group of plums 
resembling 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 )^ to i inch in diameter. They are adapted 
to ornamental usage. They are also used as stocks upon which to bud 
other plums. 

Pninus triflora. — 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, 

Pninus 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. 

Pninus hortulana. — ^This species includes a number of plums well suited 
for jelly, preserves, and spicing. They are very free of suckers. Iniportant 
varieties are American, Golden, Juicy, Ruby, Waugh, and Gonzales. The 
Hortulanas are adapted to the Southern States. 



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DRUPACE^ 401 

Prunus nigra. — ^This is the most northern of American plums. It is well 
adapted to the States along the Canadian border. 

Ptunus 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 are Robinson, Newman, Wild 
Goose, Arkansas, and Downing. 

Prunus 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, African, Clark, Emerson, etc. 

CHERRIES 

Description. — The cher- 
ries resemble plums in ^^^ 
many respects. The bark 
of the cherry separates in 
rings. The flower buds are 

usually foimd on short \ 

spurs (Fig. 166). In some y'^owth 

sour cherries, however, 
axillary flower buds occur 

on long, strong shoots. y ^^ 

These buds produce fruit • j9Mi. 

the following spring. Since ^3ca^^3 

the lateral buds in such - 

shoots are flower-bearing, n\\\ 

no lateral branches are pro- 
duced, and the result is a 

long, naked branch. On the 13 

spurs, the flower buds are « ^*" 

axillary and a branch bud Fig. 166. — spur of sour cherry (Prunus 

terminates the short shoot. cerasus). 

Tht flower buds bear only flowers and no leaves (except very 
rudimentary ones which persist but for a short time). There 

26 



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402 BOTANY OF CROP PLANTS 

are from two to five 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 
California have been shown to be self-sterile. It is altogether 
possible that sterility in cherries is widely spread. 

Groups of Cherries. — ^According to Bailey the principal 
cultivated cherries are from two spedes, 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, lighter 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 36. 
Self-sterility 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. 

GeograpliicaL — ^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 



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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 P, 
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. 

PRUNUS CESASUS (Sour Cheny) 

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. — Twig 
of sweet cherry 
(Prunus avium). 
(After Paddock 
and Whipple.) 



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404 



BOTANY OF CROP 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. 

Geograpliical. — 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. emarginata, P, pumilay P. cuneata, and P. 
besseyi, P. pennsylvanica is sometimes used as a 
stock on which to bud the sour cherry. 

Prunus mahaleby 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.) 



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DRUPACEiE 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 
stuff. 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 



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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-aciuninate, 
smooth above, slightly 
hairy beneath, finely 
toothed,* on glandular 
petioles, and convolute in 
vernation. 

Inflorescence and 
Flowers. — ^The flowers*are 
solitary 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.) 



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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. sibiricaf 
the Siberian apricot, P. dasycarpa, the purple or black 
apricot, and P. mume, 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 off 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.) 



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408 BOTANY OF CROP PLANTS 

a branch bud (Fig. 170). In this respect, they are similar 
to the apricot. 

Leaves. — ^These are conduplicate (Fig. loi) in the bud, 
elliptic 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 
stone is compressed, pointed, and pitted. The seed is of 
the shape of an almond, aromatic, and slightly 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, persicaj 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. 

Tjrpes 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 roimd 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 slight; the fruit is 
slightly flattened, with a peculiar long, conical apex more 
or less recurved, small, oval, and has a very deep suture at 



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DRUPACEiE 



409 



the stem end; the flesh is juicy, firm, generally white; the 
stone is free or cling. 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. A , Spanish Race ; B, South Chin- 
ese Race; C, Peen-to Race; D, stone of Peen-tC) Race; £, Persian Race; F, 
stone of Persian Race; G, North Chinese Race. (After Price, Texas Agr. Exp. 
Sta.) 

4. North China Race (''Chinese Clings'').— The stone (Fig. 
171, G) is globular, thick, its corrugations not at all promi- 
nent, cling, semi-chng or free; the fruit is large, almost glob- 
ular, and its flesh is fine-grained and juicy. It has a wide 
range of adaptabihty. Varieties: Belle, Lee Ray, Superb. 
Elberta and several other varieties are considered crosses 
between the North China and Persian races. 



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4IO BOTANY OF CROP PLANTS 

S- Persian Race, — The seed is globular, with corrugations 
prominent toward the apex (Fig. 171, E, F) ; the fruit is much 
like 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. Peaches 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 1915 was 64,218,000 busTiels, which were 
sold at an average farm price of 81.1 cents. Cahfomia 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 



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DRUPACEuE 411 

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 conamon almond is a native of Asia. 

Tjrpes of Almonds. — The two general types or races of 
common almonds are the bitter and the sweet. The difference 
is in the composition and taste of the kernel. The sweet or 
edible almonds 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; ahnond 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 groimd, subjected to 
great hydraulic pressure to • remove the imdesirable 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. 



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412 BOTANY OF CROP PLANTS 

References 

Bailey, L. H: Fourth Report on Japanese Plums. Cornell Exp. Sta. Bull. 

175- 131-160, 1899. 
Bailey, 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.: Uber 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: 1-616, 1911. 
The Blooming Season of Hardy Fruits. N. Y. Agr. Exp. Sta. Bull. 407 : 

367-391, 1915. 
Hendrickson, a. H.: The Common Honey Bee as an Agent in Prune 

Pollination. Calif. Agr. Exp. Sta. tull. 174: 127-132, 1916. 
Hume, Harold H. : The Peen-to Peach Group. Fla. Agr. Exp. Sta. Bull. 62 : 

S05-519, 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: 349-35 1> iQoo. 
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, 191 5. 
Native American Species of Prwnw5. U. S. Dept. Agr. Bull. 179: 1-75, 191 5. 



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CHAPTER XXIX 
LEGUMINOS^ (Pea Fanuly) 

The pea family is one of wide geographical distribution, 
occurring both in temperate and warm climates. 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 apphed to members of the 
Leguminosae. Probably no family is of greater agricultural 
importance than this one, imless it is the Gramineae. Legu- 
minous plants are comparatively rich in protein; this apphes 
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 animals, 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 {Pseudomonas 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 



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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 imder. 

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 {Robinia and 
Gleditsia, locusts), and a very few are vines {Vicia spp., 
vetches). 

Leaves. — These are alternate on the stems, stipulate, and 
mostly compoimd. They are generally odd-pinnate, that 
is, a leaflet terminates the rachis of the leaf, as in Robinia 
(locust). Astragalus (vetches) and 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). 

Inflorescence. — 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 imequal. The petals are usually five in 
number, a broad^upper one {standard, banner or vexillum)^ 



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X-EGUMINOS-ffi 415 

two lateral ones {wings or alal), 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 {monadelphous) y 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 So phot a and Thermopsis, 



-H — Mndr*''^ 




Fig. 172. — Flower of Leguminoss. A, floral diagram of Vicia faba; B, 
sweet pea flower, dissected, diagrammatic. (A after Eichler^ B after Bergen 
and Caldwell.) 

The imited 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), 



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41 6 BOTANY OF CROP PLANTS 

the fruit is a loment, that is, a jointed indehiscent legume, 
constricted between the seeds. The style, calyXy 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 viabiUty 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 huUer is effective as an 
abraser, as is shown by the experiments of Harrington who 
found that alfalfa seed, grown imder 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 Genera of Leguminos-^ 

Plants with tendril-bearing leaves (Fig. 19). 

Calyx lobes leafy; stipules large, rounded (Fig. 19), Pisutn (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), Laihyrus 
(yetchling). 
Plants without tendril-bearing leaves. 
Leaves palmately three-foliate (Fig. 183), Trifolium (clover). 
Leaves pinna tely three-foliate, rarely five- to seven-foliate (Fig. 182). 



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LEGUMINOSiE 



417 



Flowers small, many in a cluster. 
Flowers in slender, spike-like racemes, Melilotus (sweet clover). 
Flowers in heads or short spikes, Medicago (alfalfa and other medicks). 
Flowers medium to large, few in a cluster. ^ . 

Pods smooth, mostly large. 

Keel of corolla spirally coiled (Fig. 176, A), Phaseolus (bcan).^ 
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 
("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 compoimd, the component parts being about one-half 
the size of the grains in smooth peas. The seed coat is 
27 




Pig. 173. — A, style and stigma of 
Vicia; B, same of Lathryus. 



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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 axDs 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 aadls pigmented; comparatively hardy Pisum sativum (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 
shelling peas into two groups: Round or smooth-seeded^ and 
wrinkled-seeded. Each of these is divided into (i) tall climb- 
i^gj (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, roimd seeds, while the late sorts have 



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LEGUMINOSJE 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 Corhett.) 

are sometimes classified as to their time of maturing into 
early, medium, and late or m^in 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. 



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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. 175. — Pea pods showing types and range of 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 Corbett.) 

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. 



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LEGUMINOS^ 421 

Peas and Mendeiism. — Gregor Mendel'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 
MendeVs Laws, He selected a number of differentiating (paired) characters 
and observed their behavior when crossed with each other. In the brief 
sunmiary, 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 cotyledons 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 axils 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 m 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 live 
stock, particularly hogs and sheep, on field peas. 

PHASEOLUS (Bean) 

Description, — Representatives of this genus are annual or 
perennial herbs or vines ^th pinnately three-fohate, 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 five-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 keelis characteristically spirally 
coiled (Fig. 176, A). The stamens are diadelphous (nine 
and one). The ovary has a style longitudinally bearded, and 



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422 



BOTANY OF CROP PLANTS 



numerous ovules. Members of the genus are quite regularly 
visited by insects. The pod is linear, straight or curved, 
subterete 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.y 
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 Phaseolus 
are tropical and warm-country 
plants. According to Britton and 
Brown, there are close to i8o 




Fig. 176. — Common kidney bean 
(Phaseokis vulgaris). A, spiral keel; B, 
entire flower. X 2H- 



species. 

A number of "beans" do not 
fall within the genus Phaseolus^ for example, broad bean iyiciafaba), soy 
bean {Soja max), velvet bean {Mucuna uHlis)y asparagus or dolichos bean 
(Vigna sesquipedalis), cowpea or bean {Vigna sinensis) y^Ja,ck^he3,n (Cana- 
valia ensiformis)y locust bean (Ceratonia siligna) and hyacinth bean, bonavist 
or lablab (Dolichos lablah). 



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LEGUMINOS^ 



423 



The adjuki bean {Phaseolus angularis) and mung bean {Phaseolus aureus) 
are now grown to some extent in this country. 

Key to Principal Species of Phaseolus 

Roots tuberous or much thickened, P. multiflorus (scarlet nmner bean). 
Roots fibrous. 

Seeds flat or flat-oval in cross-section, P. luncUus (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 trifoliate leaves. The large and showy 
flowers are scarlet (scarlet runner), ''or white (Dutch case- 




FiG. 177. — Pistil of flower of common bean (Phaseolus vulgaris). 

Knuth.) 



(After 



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 nmner 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 



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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 midtijlorus. 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 trifoUate, 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 Tjrpes of Lima Beans. — There are two 
general types of Limas, as follows: (i) Phaseolus lunatus, 
including the Sieva or Carolina 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 Relationseop of Types of Lima Beans 

Phaseolus lunatus (Sieva, Civet, or Carolina beans). 

Plants bush (Henderson's Bush Lima). • < 

Plants pole (Small White Lima, Florida Butter). 
Phaseolus lunatus var. 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). 



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LEGUMINOS^ 



425 



a 








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 Corhett.) 



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426 BOTANY OF CROP PLANTS 

Seeds smaller; pods short and thick, with prominent tqi; leaflets tap e riig» 
long ovate, PotcUo Limas, 
Plants bush (Dreer's Dwarf Lima). -• 

Plants pole (Drecr*s Improved). 

PHASEOLUS VULGARIS (Kidney Bean) 

These are annual plants, with pinnately 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 bush. These in turn each possess 
green-podded and wax-podded sorts. The bush beans are 
often grouped together imder the variety P. vulgaris nanus. 
Most of our common garden sorts are dwarf or bush beans. ^ 

The stringiness 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 Descrq)tion. — The Vicias are climbing 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. 



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LEGUMINOS-ffi 



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 oDary has 
numerous ovules and a slender 
style with a tuft or ring of hairs 
at its simimit (Fig. 173, A). 
The pod is flat. 

Geogw^hical.— 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 Wicia 

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), F. villosa (hairy vetch). 
Leaves truncate at tip; flowers few, 

usually two in each leaf axil, 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. DepL Agri.) 



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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 vetch {Vicia angustifolia) 
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 ervilia) 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 



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LEGUMINOS-fi 429 

vetch (Vicia fulgens)y Narbonne vetch {Vicia narbonnensis) and woolly podded 
vetch (Vicia dasycarpa) are rather raid 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 VictGy for example: Crown vetch (Coronilla sp.), kidney vetch (Anthyl- 
lis vulneraria), Dakota vetch {Hosackia americana) and Lathyrus 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 ysrhich 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 pedimcled, 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. 



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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 VnXOSA (Haixy, 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 accoimt 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 leafletSy 
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 imdergroimd at germination, as is the 
case in the common garden and field pea. Hairy vetch is a 



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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. 



Fig. 182. — Hairy vetch (Vicia villosa). 



Hot simimer weather is very harmful to its growth. It is 
frequently planted on light, sandy soils, where it may be 
plowed imder as a green manxire. 



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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, Wild 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 LathyruSy 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: Z. tingitanus (Tangier pea), 
L. cicera (flat-podded pea) and L. 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, Trifolium) 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. 



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LEGUMINOS^ 433 

Geographical. — There are close to 300 species of Trifolium^ 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. alexandrinum (Berseem) 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. incarnaium 

(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 acununate (Fig. 183, A), T. hyhridum (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). 

TRIFOLIUM 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, trifoUate leaves 
have inversely h^art-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 



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434 BOTANY OF CROP J?LANTS 

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. 

Enviroimieiital 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 dover) 

Descrq)tion. — 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 coimtry for agri- 
cultural purposes and has escaped from cultivation, often 
being foimd 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 



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LEGUMINOSiE 435 

for planting at high altitudes and latitudes. It is prized as 
a honey plant. 

TRIFOLIUM mCARNATUM (Crimson, Scarlet, or Italian Clover) 

Descrq)tion. — 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) ; 
2>, 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-like 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. 



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436 BOTANY OP CROP PLANTS 

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 w 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 poimds 
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. 

Liflorescence 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 



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LEGUMINOSiE 437 

per head than the first crop. The flowers are of the ordinary 
pea type, except that the petals are united at their bases aijd 
to the staminal tube to form a corolla-tube about J^ 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- 



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438 BOTANY OF CROP PLANTS 

men 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 
abimdant 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. 
Fruit^ of ^^red When the capsule is mature, the stylar end 
clover (Trifo- separates from the basal part by an irregular 
m^he^argS'. transverse line. The upper part of the cap- 
sule, together with the style, comes off as a 
lid (Fig. 185), and the sinfle 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 pollinators. When the bumble- 
bee lights on the clover head and inserts its proboscis into 
th^ 3taminal tube, its weight presses down on the keel and 



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LEGUMINOS-ffi 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. 

Enviromnental 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 like 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 ordinary TrifoUum 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 TrifoUum 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 himaid 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. 



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440 BOTANY OF CROP PLANTS 



Fig. 1 86. — A vigorous alfalfa plant showing the **crowjr^^i:oi:ial;which 
arise the numerous shoots. {After Headden, ^Mtm^A/ghPMxp, Sta.) 



leguminosJe 441 

TRIFOLIUM MEDIUM (Zigzag, Medium Red, White, Mammoth or 
Meadow Clover) 

This is a perennial clover resembling red clover {T. pra- 
tense), 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 country and occurs here and 
there in the eastern United States as 
a ruderal. 

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 / 
alfalfa, and very rarely shrubby (one 
species in southern Europe). The 
leaves (Fig. 183, E) are pinnately 

three-foliate, the stipules adnate to fig. 187.— Seed and pod 
the petiole, and the leaflets com- of alfalfa (Medicagosativa). 

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 



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442 BOTANY OF CROP PLANTS 

ovary is sessile or short-stipitate, and several- cm: rarely one- 
ovuled; it has a subulate (awl-shaped), and smooth style. 
The pods (Fig. 187) are curved or sf^rdly twisted, veiny or 
spiny, and indehiscent. 

GeographicaL — There are a niunber of species of Medi- 
cagOy 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 p>erennial 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 saUva (alfalfa). 
Annual, low-growing plants; flowers yellow. 
Pods kidney-shaped, without spines, Medicago lupulina (hop clover). 
Pods cylindrical, with spines. 

Stems pubescent; pods 3 3^ to 5 millimeters diameter; purple spot in 
center of each leaflet; two to eight seeds in each pod, Medicago arahica 
(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 SATTVA (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 
foimd 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 



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LEGUMINOSiE 443 

the variety. The average Kfe 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 t3T)es is more spreading and the numerous buds and 
shoots come from below the soil surface. Hence in the latter 
case, the buds and yoimg 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 yoimg 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 ofalfalfa 



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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 poimds of 
nitrogen, 17 poimds of phosphorus, 99 pounds of potassium, 
and 90 pounds of calcium. 

Lreaves. — 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 suflScient 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 



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LEGUMINOSiE 445 

"automatic" tripping. Humidity and temperature condi- 
tions are probable causative factors in automatic tripping. 
Both self- and cross-pollination are effective in alfalfa. 



unl 



Pig. 1 88. — Pollination of alfalfa. A, flower untripped with calyx and 
standard removed; B, same tripped; C, position of staminal tube untripped 
and tripped. {After U. S. Dept. 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 



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446 BOTANY OP CROP PLANTS 

of pods set and the number of seeds p>er 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 applied 
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 amoxmt 
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 }4 ii^ch long. The seeds 
retain their viabiUty for many years. 

Germination and Seedlmg. — 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 aU 
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 



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LEGUMINOSJE ' 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 (GrinMn, for example) 
owe their hardiness to the possession of a small percentage 
of the "blood'' of the hardy yellow-flowered or sickle alfalfa 
(Medicago falcata). Numerous forms of alfalfa arise where 
ordinary alfalfa {M. sativa) and yfellow-flowered alfalfa (M. 
falcata) 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 
{Medicago media) is considered by some botanists to be a 
natural hybrid between M, sativa and M. falcata; 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 little smaller, and the leaves are 
narrower and more hairy, than other common sorts. German 



1 



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448 BOTANY OF 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 imder irrigation in the southwest, where the winters 
are mild. Brand proposes to place Peruvian alfalfa as a 
distinct variety {Medicago sativa var. polio). 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. " 

EnvJromnental 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 
t3T)es 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). 

p.__^ Water 

'^'°P 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 



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> LEGUMINOS^ 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 m 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, Cali- 
fornia and Idaho. 

MEDICAGO LUPULINA (Hop Clover, Black Medic, Yellow TrefoO) 

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 cyHndrical 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 



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4SO 



ROTANY OF CROP PLANTS 





• • • 


• • ^ 


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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. DepLlof Agr.) 



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LEGUMINOSiE 45 1 

(Fig. 189) are in long clusters, twisted into three to five 
spirals, and the edges bear numerous grooved spines which 
interlock. The seeds are kidney-shaped, and about 2 J^ milli- 
meters long. Medicago arahica inermis is a spineless-podded 
form. 



Fig. 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. 



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452 BOTANY OF CROP PLANTS 

MEDICAGO mSPIDA (Toothed Bur 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. The flowers are yellow. The pods are netted- 
veined, twisted spirally, and spiny. The seeds are light- to 
brownish-yellow, kidney-shaped, and about 3 millimeters 
long. Medicago hispida reticulata and M, hispida confinis 
are forms with spineless pods. Toothed bur clover, Medi- 
cago hispida denticulataj is native to the northern Mediter- 
ranean region. It is the most common bur clover grown in 
Cahfornia. 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-foliate, 
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-like 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 



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^ 



LEGUMINOSiE 453 

germinate the first season. This results from the production 
of sonie "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 and inflorescence of white sweet clover (Melilotus alba) on 
left, and alfalfa (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 
Melilotus: M, alba, white sweet clover, and M, officinalis, 



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454 BOTANY OF CROP PLANTS 

yellow sweet clover. Several other species of Melilotus 
have been used agriculturally to some extent; among such 
are M, indicfL (*'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 
line. The leaves iiave 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 



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I 



LEGUMINOSiE 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, like the preceding 
species, has become naturalized in this country, being widely 
distributed as a ruderal throughout both the Northern and 
Southern States. 

Enviromnental 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 Glovers. — 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 pinna tely 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. 



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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, Cofifee Bean) 

Description. — This is an erect, bushy appearing, hairy 
annual, varying from i % 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 and 
strong. The leaves are tri- 
foliate. 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. 

Fig. 192.— Soy bean (Soja max). The flowers are Self -pollinated 
{After Piper.) ^^ ^ j,^j^^ ^^^ ^^^ Completely 

self-fertile. Occasional cross-fertilization occurs in the field 
when varieties are planted very close together. The pods 
are from i to 2j^ inches long, yellowish or brown, and 
covered with short bristly hairs. As many as 300 to 4CX) 
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 



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. LEGUMINOSiE 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 
viability 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 utilized to 
make a so-called soy-bean milk, which is valued for cooking 

* Data from the U. S. Dept. of Agri. Bureau of Chemistry. 



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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 
trailing 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 sue diadelphous 
(nine and one). The ovary is sessile, many-ovuled, and 
bears a style that is bearded along the inner side. The 
pods are Unear, straight or sKghtly curved, and two-valved. 
The seeds are much like the common kidney bean in shai>e 
(Fig. 1.93). 

All the Vigna spp. (^^Vignas'O 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.) 



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LEGUMINOS^ 


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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 lies in the first i }4 fe^t 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 abimdance of water and 



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LEGUMINOS^ 461 

heat, and seed production is stimulated by adverse condi- 
tions. The first 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 cylindrical, 
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 ^^^- ips.-Cowpea (Vigna sinensis). 

(After Piper,) 

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, cylindrical pods 
with globular seeds. 



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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 
com, and like ,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 localities 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 a substitute for 
cqffee. 

ARACmS 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 imited, one abortive) 
and a minute abortive ovary. The calyx tube is long and 
slender, and bears on its rim the calyx lobes, corolla, and 



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LEGUMINOSiE 463 

Stamens; the four superior lobes 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 J 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. 



Fig. 196. — ^I*eanut'(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 ovary 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 ^^shelP' of 
the '^peanut'' is the pericarp; the thin skin that surrounds 
each seed or pea ("nut'O is the testa. The cotyledons are 
large, and rich in stored food. 



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464 BOTANY OF CROP PLANTS 

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 ''JumbosJ' 

Enviromnental 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 
''"hV'^o7SnAJrr„*i^.r''^ 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 



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LEGUMINOS-ffi 465 

are other products. The nuts ("goobers") are 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 viciflefolia (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 



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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 



Fig. 198. — Chick pea (Cicer 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. 



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LEGUMINOSiE 467 

Cicer arietintun (Chick-pea). — A bushy, hairy annual, i to 2 feet high, 
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 stock 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 ARTLETT, G. : The Native and Cultivated Vicieae and Phaseoleae of Ohio. 

Ohio Nat., 15: 393-404, 19 14. 
Beal, a. C. : Evolution and Pollination of the Sweet Pea. Florist*s Exch., 

32: 140-141, 1911. 
Beattie, W. R.: Peanuts. U. S. Dept. Agr. Farmers' Bull. 356: 1-40, 1909. 

The Peanut. U. S. Dept. Agr. Farmers* Bull. 431: 1-39, 191 1. 
Blinn, Philo. : Alfalfa — the Relation of Type to Hardiness. Colo. Agr. Exp. 

Sta. BuU. 181: 1-16, 1911. 
French, G. T.: Observations on Medicago lupulina L. Science, n. s., 2, 

28: 127, 1908. 
FucsKO, Mihaly: Uber die biologischen und entwickelungsgeschichtlichen 

Verhaltnisse des Pericarps der Papilionaten. Ung. Bot. BL, 8: 264-265, 

1909. 
Anatomie, Entwickelung und Biologie der Fruchtwand der Papilionatae. 

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 Selbstbestaubung 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, 191 5. 
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, 191 7. 



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468 BOTANY OE CROP PLANTS 

Pamicel, Edna C, and Clark, Clarissa: Studies in Variation of Red Clover. 

Proc. la. Acad. Sci., i8: 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. Dept. la. State College, 47 : 1-45, 1911 . 
Pfenninger, Urs.: Untersuchung der Fruchte von Phaseolus vulgaris L. in 
verschiedenen Entwickelungstadien. 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: 

i-iS, 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, 191 2. 
ScoFiELD, Carl S.: The Botanical History and Classification of Alfalfa 

U. S. Dept. Agr. Bur. Plant Ind. Bull. 131: 11-19, 1908. 
Shaw, Thomas: 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, 1910. 
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, 191 2. 
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. 



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CHAPTER XXX 
LINACEiE (Flax Famfly) 

Habit, Stem, Leaf. — The species of this family are annual 
or perennial herbs, or shrubs. The plants are tap-rooted, 
and each tap root bears a number of slender, lateral branches. 
The steins are single. The leaves are simple, narrow, nearly 
sessile, and usually alternate, although sometimes opposite 
(L. catharticum) . 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 cor)mib or c)mie, or the flowers may be 
more or less scattered on the branches. The 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 imited 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 imited 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 capsule apparently ten-celled (Fig. 21). 

469 



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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 requirement 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 



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LINACEiE 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. — Common flax (Linum usitatissimum) . 

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 



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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. 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 
3^^ 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^ to }i inch. 
They are lenticular, compressed, and slightly 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. 



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LINACEiE 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 
groimd into a meal, and 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 yams, fishing lines, seine twines, 
etc. It is also employed to some extent for upholstering, 
for insulating cold-storage plants, refrigerator cars and ice 



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LINACEiE 475 

boxes. A fine grade of paper (linen paper) 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 bimdles. The bundles are 
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 poimded 
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 raisfes a very 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 1914 were North Dakota, Minnesota, 
Montana, South Dakota, and Kansas. 



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CHAPTER XXXI 

RUTACE^ (Rue Famfly) 

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; the 
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.) 



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RUTACEiE 477 

Key to Important GfeNERA of Rutace^^ 

Leaves trifoliate, Poncirus (trifoliate orange). 
Leaves unifoliate. 

Ovary three- to seven-celled; ovules two in each cell; stigma cavernous, 

Fortunella (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. 



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478 BOTANY OF CROP PLANTS 

late, glaucous, leathery, evergreen, and unifoliate (with the 
exception of Citrus trifoliate) ; the leaf stalk is usually articu- 
lated to the blade and also to the twig. The life 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 solitary, 
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, imited at their bases to form 
groups; the ovary possesses 8 to 75 cells 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 imless pollen is derived from certain 
congenial varieties. Pollination may occur without the 
visitation of insects. The time for complete fertilization 
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." 



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RUTACE^ 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 either leathery 
or membranous; endosperm is lacking; each seed has two 
or more embryos with fleshy, hypogean cotyledons. The 
poly embryonic 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 imion 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 Malay Archipelago, 
and adjacent Asiatic territory. 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 oi: reddish outside. 

Stamens 30 to 40; fruit 6 to 9 inches long, its skin thick, C. medica (citron). 
Stamens 20 to 30; fruit about 3 inches long, its skin medium thick, C. 
limonia (lemon). 



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480 BOTANY OF CROP PLANTS 

Petals white both on the inside and outside. 
Leaves wingless or narrowly winged. 

Fruit small, i J4 to 2}^ inches in diameter, its skin thin, C. auranlifolia 

(Ume). 
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 "fingered 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 extent 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 



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RUTACE^ 481 

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 10 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, 

Sta.) 

sometimes in small clusters; their petals are white inside, 
and purplish above; the stamens are usually between 20 
and 30 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. The 
first class is the only one to set fruit. The fruit is about 3 
31 



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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 Lremon 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 them 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 
machine method. There are two sponge methods, known as 
the two-piecCj and three-piece sponge methods. In the former 



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RtJTACE^ 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 slightly 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, cr^nate, 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 ij'i to 23^ 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." 

"Limeqtiat." — The "limequat" is a hybrid between a 
kumquat and the Mexican lime. 



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484 BOTANY OF CROP PLANTS 

CrrRUS 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 flowers 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, light 

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. 

Types. — 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. 



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RUTACE^ 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 nobilis var. 
unshiu is the Satsimia 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, 



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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. Sta.) 

Geographical. — The species is a native of Polynesia and the Malay Archi- 
pelago. It is now grown in the United States. 



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RUTACEiE 487 

Variety and Name.— The name grapefruit is the one that 
this species is known by comp;iercially. 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 AUKANTIUM (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. 

Geografkhical. — 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, 



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BOTANY OF CROP PLANTS 



and each cell contains two ovules; a characteristic feature of 
the flower is the cavernous stigma; the fruit is small, i to 
1 3^ inches in diametet, its rind usually thick, fleshy, spicy, 




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 Fortunella 
are F. margarUaj the Oval or Nagami kumquat, and F. 



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RUTACEiE 489 

japonica, the Round or Marumi tumquat. 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. 

PONCIRUS, (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 i3^ inches long, and flattened at the base; the 
characteristic deciduous trifoliate 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 
allies in being oval, rounded at one end and blunt-pointed 
at the other. The pulp is acid, bitter, and gummy. 

A Hardy Orange. — The trifoliate 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. 



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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. St^. Bull. 66: 571-594, 1903. 
Citrus Fruits and Their Culture. Orange Judd Co., 19 13. 
Ikeda, Tomochika: On the Parthenocarpy of Citrus fruits. Jour. Sci. Agr. 

Soc. Tokyo, 63, 1904. 
OsAWA, I.: 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. 



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CHAPTER XXXII 

VITACEiE (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 (ViHs) 
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-dioecious 
(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). 



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492 



BOTANY OF CROP PLANTS 



Key to Important Genera 

The three most important genera are VUis (grape), Cissus (pepper 
vine) and Parthenocissus (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, Parthenocissus (Virginia 
creeper, American ivy). 

VITIS (Grape) 

Stems. — Grapes are cKmbing or woody 
vines with tendrils. The stem is jointed. 
The intemodes 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 
priming 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 




Fig. 207. — Two 
types of grape 
stems cut in me- 
dian lengthwise , i. r i 11 

section. A. south- below or near the surface of the ground and 

( vkis ^TotundHo- shouM be removed. Water sprouts arise 

lia) with pith con- from dormant buds above ground. They do 

nodes; JB. old not produce fruit. If dormant buds de- 

^rdferaV^h ith ^clop, producing these sterile shoots, it in- 

interrupted at the dicates that there is not a sufficient number 

nodes. (After ^^ ^^^^ ^^^^ ^^ ^^^^ ^^^^ ^^ ^^ ^^ ^^p 

co.ming to aerial parts. Water sprouts should 



Hedrick.) 



be removed during winter pnming. 

Tendrils, morphologically, are modified stems. 



This is 



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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- 



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494 BOTANY OF CROP PLANTS 



Fig. 209. — Fruit-bearing shoot of river-bank grape (Vitis riparia). {After 

Hedrick.) 



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VITACEiE 495 

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 imtil 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 



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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. 




— nectar 
^and 



Fig. 210. — Grape flower, opening. X 20. 

The flowers (Fig. 2 10) 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. Whep the 
flower opens, the petals become loosened at the base but 
remain united by the tips. Stamens are five in number and 



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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. 210). 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 five 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-fertilized, usually 
possess short stamens. However, long stamens and short 
stamens are not absolute criteria of self-fertility and self- 
sterility 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 
32 



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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-steriUty 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 fertilization. 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 diflBculty 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 
jdiffer 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. 



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VITACE^ 499 

Key to Most Important Species of Vitis^ 

Skin of mature berry not separating freely from the pulp, Vitis vinifera 

(Old World grape). 
Skin of mature berry separating readily from the pulp. 

Nodes without diaphragms (Fig. 207, A) ; tendrils forked, Vitis rotundifolia 

(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. rupestris (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. cBsHvalis (summer grape). 
Leaves covered with a dense, thick, felt-like tomentum when fully 
grown, V. lahrusca (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 yomig; 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 iif CaUfornia, where the wine and raisin in- 
dustries have developed to considerable importance. F.- 
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. 

^The key is adapted from "The Grapes of New York," by Hedrick. 



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500 BOTANY OF CROP PLANTS 

VUis 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 
heart-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. 



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VITACEiE 501 

By far the greatest number of cultivated grapes are varie- 
ties of this species, or hybrids from it and other species, 
chiefly VUis vinifera, the Old-World grape. 

Varieties of Table Grapes. — There are four very common 
varieties of table grapes: 

1. Catawba J hybrid of V, labrusca and V, vinifera. 

2. Delaware, hybrid of V. labrusca and V. bourguiniana, 

3. Niagara, hybrid of F. 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, Jefferson, 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. 

Uses. — 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 light-colored raisins made 



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S02 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 sim, 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- 
mienting juice. In the making of red wines, the skins and 
piilp are crushed and placed in fermenting vats. The im- 
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 



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VITACE^ 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 angelicas. 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 angelica 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 



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S04 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. ii: 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. 
Dorse Y, 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. 



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CHAPTER XXXIII 

MALVACEiE (MaUow FamUy) 

Habit. — Members of the family are herbs, shrubs, or 
trees. Tree species are tropical. The mallows are usually 
rich in mucilage. 



Fig. 211. — Diagram showing arrangement of parts in the cotton flower. 
(After Cook, U. S. Dept. Agri.) 

I/eaves. — The leaves are alternate, and mostly palmately 
veined and palmately lobed. The stipules are small^ narrow, 
and deciduous. 

505 



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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 {AUh<Ba)y 
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 AbuHlon, 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), 



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BIALVACEiE $07 

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 imited with the bases of the petals (Fig. 212). There are 
five more or less distinct projections at the top of the tube 
of stamens; this seems to indicate that there are in reab'ty 
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 



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5o8 BOTANY OF CROP PLANTS 

(Malva spp.), poppy mallow (CalUrhoe spp.), AbuHlon 
and Hibiscus. The Rose of Sharon is Hibiscus syriacus. 

Key to Important Genera of MALVACEiE 

Stamen column anther-bearing at the summit. 
Carpels one-seeded. 

Involucre of six to nine bractlets, AUhcBa (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, Callirho'i (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 Gossypiufn, 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. 

Steins. — The main stems are erect and branching. The 
usual height of Upland cotton plants is 2}^ 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 limbs may arise 



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MALVACEiE 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; I>, 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. 



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SIO 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 differ 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 iQ 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 
pronoimced 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 



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MALVACEAE 5II 

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 
undergroimd 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. 

I/eaves. — 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 arr.angement 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 
intemode 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 



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512 BOTANY OF 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, 



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MALVACEAE 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. 

^^ Intrdcalicary 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. barbadense 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 colunm 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. 
33 



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514 BOTANY OF CR01> 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 imtil 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 suboyate. 

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 abimdance of long 
fibers. A high percentage of Unt usually indicates small 



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MALVACE^ 515 

seed. In some varieties, the Knt may form 34 per cent, or 
more of the seed. 

Distriiution of Seed Hairs, — ^Lint and fuzz are mixed to- 
gether over the entire seed surface in Upland cottons. In 
Eg3^tian sorts, fuzz is limited to the ends of the seeds, with 
long fibers between the two patches. The lint at the tip of 
the seed in some Upland cottons is longer than that at the 
base. 

Fiber inferences, — 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 i .6i 0.000640 

New Orleans i .02 0.000775 

Texas i.oo o. 000763 

Upland 0.93 0.000763 

Egyptian 1.41 0.000655 

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 cylindrical and solid. The hair 
cavity or lumen takes up about two-thirds of the entire 



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5l6 BOTANY OF CROP PLANTS 

breadth. Immature fibers or imripe 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 quaUty 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 cultivation 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: 



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MALVACE^ 517 

Section I, Species with a Fuzz hut no Floss. — "Wild species (never recorded 
as met with under cultivation), distributed from the western coast tracts and 
islands of America to Australia." Here are included G. sturtiij davidsonii, 
klotzschianuniy robinsoniy darwiniiy tomentosunty 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. arboreumy G. nanking, G. obtusifoliumj 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. 
negleclay 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. herbaceum 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 1 62 1, it was brought to the United States, and for a time cultivated, but 
was finally replaced by the more desirable West Indian cottons. G. herbaceum 
is considered to be the first cotton cultivated in Europe. Watt believes 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 with Free Bracteoles. — These are Ameri- 
can and, in one case, African species. Here belong G. mustelinumy punctatumy 
hirsutum y palmeriiy fruticulosumy schottiiy lanceolatuMy microcarpumy peruvi- 
anum, and mexicanum. 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 offsprings of 
hirsutum (Fig. 214). G. palmeriiy fruticulosum and lanceolatum are Mexican 
species. G. schottii is from Yucatan, and is known as the "split-leaved" cot- 
ton. G. microcarpum, known as Ashmoum* cotton and Red Peruvian cotton, 
grows in Mexico, northern South America, Africa, and Malaya. It is culti- 
vated. G. pemvianum is the Peruvian or Andes cotton. Watt regards many 
of the Egyptian cottons as races or hybrids of this species. G. mexicanum 



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5l8 BOTANY OP 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. mexicanum)^ rather than as forms of G. hirsututn" He con- 
siders many of our Upland or short staple cottons as hybrids of G. mexicanum 
and G. hirsidumy 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 Bracteoles 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 



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MALVACE.^: 519 

"naked." To this section belong G. taitense^ purpurascens^ viUfolium, bar- 
hadensCf and brasUiense. 

G. taitense 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. vitifolium^ the vine-leaved cotton, has fur- 



FiG. 215. — Sea Island cotton (Gossypium barbadense). {After Watt.) 

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 



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S20 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 
oflf the coast of Carolina and Georgia are referred to G. barbadense var. 
maritima. G, brasUiense 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. 

Seciion V. Naked-seeded Cotton with Bracteoles 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-coloredy 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 fonns. 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 



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MALVACE^ 521 

spot at the base of each petal m Sea Island cotton. The 
latter is limited to a small area along the coast of South 
Carolina, 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 poimd of cotton; four to five locules; seeds large, 
very fuzzy, white to brownish gray or greenish in color; lint 20 to 30 miJli- 
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 with 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, Defian(», Bernett, Berryhill, 
Hawkins. 

5. Rio Grande or Peterkin 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; b'mbs 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, 33 to 35 per cent, of 
seed. Earliest American cottons. Examples: 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. 

?. Intermediate Group. — This group includes a number of varieties with 



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522 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, Tudcer. 

Enviromnental Relations. — Cottcm 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 abimdance 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 



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MALVACE^ 523 

in a type known as the roller gin, as the fiber is injured by the 
saw ^ 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 boilings in caustic soda in order to remove the 
waxy, fatty and pectic substances from the fiber. After a 
thorough washing 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 Ume compoimds 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 yams 
are from long staple upland cotton. The short lint or fuzz, 



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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 oflF some of the water. The oil is then extracted 
under pressure. A ton of se^d 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 9 13. 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 groimd 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, gossypol. Cottonseed 



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MALVACEiE 



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 




t3 4« 
CO 8 

o 

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^^ 



to ^ 



•«> 

U . 

1 M -^ 

« Ov JO 

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I ^1 









gossypol and rendering it non-toxic. Cottonseed meal is 
also highly prized as a fertihzer. 
GuncoUon. — This is a powerful explosive made by treating 



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526 



BOTANY OF CROP PLANTS 



cotton or some other form of cellulose with nitric acid or 
sulphuric acid. Military 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 gimcotton in ether and alcohol. 



^ 




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Pig. 2 17. — Cotton-producing regions of the United States. {From 
Essentials of Geography, Second Book. Copyright, 1916, by Albert Perry 
Brigham and Charles T. McFarlane. American Book Company, Publishers.) 

^portance, 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 



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MALVACE^ 5^7 

States led in cotton production, 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, 191 5. 

Production of Lint (Excluding Linters) in soo-pound Gross Weight 
Bales, by States, 19x5 

State Bales 

Texas 3>i75>ooo 

Georgia 1,900,000 

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 
leavtss 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. 



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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 i)^ 
to 33^ 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 coim tries 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: i-i6, 1905. 
Bowman, F. H.: Structure of the Cotton Fiber. Manchester, England, 1881. 
Brooks, E. C. : The Story of Cotton. Chicago, New York, and London, 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. 
DuGGAB, 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. 33: 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. 



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MALVACE^ 529 

Heizmann, H.: Die BaumwoUe. Zurich undLeipsic, 1913. 

Meade, R. M.: Methods of Securing Self-pollination in Cotton. 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 Baumwolle. 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 Baumwolle, 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, 1907. 



34 



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CHAPTER XXXIV 
UMBELLIFER JE (Carrot Family) 

Stems and Leaves. — ^AU 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 
Bupleuruffty Hydrocotyle and Oxy polls) j they are simple. In 
Saniculay they are digitately parted or lobed. In the carrot, 
fennel, and others, the leaves are decompoimd. 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 compoimd, but occasionally 
a head (as in Eryngium). The umbel is so characteristic 
of this group of plants as to suggest the name ''Umbelliferae" 
(literally 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 umbel 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 



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UMBELLIFERiE 



.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, 



—anther 





^^yf carpophores^ 

D 

.dorsal r/6 
^ — - -interval 




lateral nb 



commissural ^\ie 

Fig. 218. — Parsnip (Pastinacasativa). A, median lengthwise section of 
flower, X 12; J3, face view of same, X 12; C, dorsal view of single mericarp, X 
2>6; Dy floral diagram; £, schi-zocarp with mericarps separating at maturity, 
X 2M; ^f cross-section of single mericarp, X 10. {D after Strasburger.) 

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. 



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532 BOTANY OF CROP PLANTS 

Pruit. — The umbelliferous /rw^7 (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 m^ricarps. 
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, five longitudinal mem- 
branous or corky ribs, the primary ribs. These are modifi- 
cations of the pericarp; each encloses vascular bimdles. 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), rimning 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 soKtary 
(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 



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UMBELLITER^ 533 

whole cavity and is usually adnata 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 Importance 

Fruit bristly, Daucus (carrot). 
Fruit not bristly. 
Fruit strongly flattened dorsally, with lateral ribs more or less prominently 

winged (Fig. 218, F), Pastinaca (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, Fcmicidum (fennel). 
Involucre present; leaves ternately compound, Carum (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 first season of growth, there is a storage of food in 
the enlarged h5^ocotyl 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. 



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534 



BOTANY OF CROP PLANTS 




^imarif ndge 



ysecondaru 



In a cross-section the of ** carrot '' the following tissues 
may be seen, from the outside to inside: (i) periderm (skin); 
(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 decompoimd (doubly 
compoimd). The lower 
ones are two- to three- 
pinnate, the segments 
linear 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. 



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UMBELLIFERiE 



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 (vittae) are solitary in the in- 
tervals, that is, imder 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 carota is a native of Europe and 
Asia. It has become common throughout North America, in many places 
proving a troublesome weed. All the cultivated forms of carrot are con- 
sidered to be derived from this one wild form. 




Pig. 220. — Types of carrots (Daucus carota). A, Garden Ball; B, Early 
Scarlet; C, Oxheart; D. Chantenay; £, True Danvers; F, Saint Vallery; G, 
Long Orange. 

Varieties. — There are numerous varieties of carrots vary- 
ing as to size, shape, color, and quaKty. As to shape of 



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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, RootSy 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 
compoimd, 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. 



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UMBELLIFERiE 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 involucels 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 oval and 
much flattened dorsally. The dorsal and two intermediate 



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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 sohtary in the intervals; there 
are four on the dorsal side and two to four on the conmiissural 
side. The olive-green seeds are flattened dorsaUy. The 
seeds are very short-lived. 

Geographical. — The wild parsnip, Pastinaca saiiva^ from which our culti- 
vated varieties are derived, is a native of Europe. This wild form has be- 
come naturaiized 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 is; J5, 
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 greenish flowers are in compound umbels. The involucre 
and involucels may be present or wanting. The calyx teeth 



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UMBELLIFERiE 539 

are absent. As in many umbellifers, the petals are turned 
in at the tip. The fruit (Fig. 222) is flattened laterally, 
broader than long, sniooth or covered with protuberances. 
The mericarps have pronounced corky ribs; the oil tubes are 
soUtary 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, Apium leptophyllum. These three species are distinguished in the 
following key. 

Key to Principal Species of Apium 

Flowers greenish-yellow, Apium petroselinum (common parsley). 
Flowers white. 

Leaf segments broad, Apium graveolens (celery and celeriac). 

Leaf segments narrow, Apium leptophyllum (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: 



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540 BOTANY OF 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 stimted 
or set back in their development, seed stalks may be sent 
up the first season. Of course, in celery growing, the 
^^ seeder s^^ are imdesirable 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. 

Geographical. — Apium graveolensj 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, tumip- 



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UMBELLIFEILffi: 54I 

like rootstock, 2 to 4 inches long. These rootstocks con- 
stitute the edible portion of the plant (Fig. 223). 

There are two general types of the common celery: (i) 
self-blanchifig varieties — quick-growing, very tender, easily- 
blanching sortSj 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 Vilmor in.) 

Ught; 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 Ught. 

(2) Green or winter varieties — not as quick-growing or 
easily blanched as those of the preceding type and, further- 



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542 BOTANY OF CROP PLANTS 

more, with better keeping qualities when stored for the winter 
(Giant Pascal, Boston Market, Winter Queen, Giant White 
SoUd). 

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. 



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CHAPTER XXXV 
VACCmiACEiE (Huckleberry Famfly) 

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 (GauUheria), American Laurel {Kalmia), Labra- 
dor tea (Ledum) y Azalea; Rhododendron, and trailing arbutus 
(Epigcea 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 



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544 



BOTANY OF CROP PLANTS 



,^^^ 



m ^ 



berry, or Vaccinium memhranaceum, the thin-leaved bil- 
berry), or in racemes (as in Vaccinium virgaPum, southern 
black huckleberry, or Vaccinium oxycoccus, 
the European cranberry). The flower 
pedicels are usually bracted. The small 
flowers are perfect, s)anpetalous, and usu- 
k Y %p ^ y«^ ally actinomorphic (Fig. 224). The calyx 
\^<S^o/ (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 

— j/yfe - 

anther 
olla 



Fig. 224. — Floral 
diagram of Vaccin- 
ium. 




'inectar 
^calyx tube^ 
ovules 



Fig. 225. — Flower of Vaccinium. A, median lengthwise section; B, 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 




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VACcmiACE^ 545 

upwardly prolonged into tubes, and open by a terminal pore 
(Fig. 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 fruit is globular and either a many-seeded 
berry (as in Vaccinium) or drupe-like (as in Gayltcssacia) . 
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. 

Pollination. — 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-pollination is to a large extent prevented. 

If pollen from the same plant is used in pollination, the fruit 
that is formed remains small and green, and later drops off, 

35 



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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 VAcaNiUM 

Fruit red in color. 
Stamens included, V. viHs-idcea (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 
macrocatpon (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. ccspitosum (dwarf bilberry). 
Leaves not shining above, V. vacillans (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, 7. angustifolium (low blueberry). 
Fruit without bloom, V, nigrum (low black blueberry). 
Leaf surfaces hairy, V. canadense (Canada blueberry). 



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VACCINIACEiE 547 

Plants tall, 3 to 1 2 feet, and spreading. 

Flowers solitary in leaf axils, V. ovalifolium (tall or oval-leaved bilberry). 
Flowers in groups in leaf axils. 

Fruit blue, V. corymbosum (high-bush blueberry, swamp huckleberry). 

Fruit black, V. atrococcum (black blueberry). 

GAYLUSSACIA (Huckleberry, Tangleberry, Dangleberry) 

Descrq)tion. — 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-Uke 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. frondosa (blue huckleberry, tangleberry, dangle- 

berr}'). 
Fruit without a bloom. 
Leaves 2 to 4 inches long, G. ursina (Carolina huckleberry). 
Leaves i to 2 inches long. 

Bracts small, deciduous, G. resinosa (black or high-bush huckleberry). 
Bracts large, persistent, G. 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. 



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BOTANY OF CROP PLANTS 



CRANBERRIES 

Some botanists place the cranberries in the genus Oxycoc- 
cuSy separate from the blueberries, huckleberries and bil- 
berries, which are included in the genus Vaccinium. In 
Oxycoccus 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 




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 



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^ACCINIACE^ 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 light 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 Americsi. 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 ozycoccus (Small Cranberry). — This is the 
cranberry of the Old World. It is a slender, creeping plant 
with thin stems, 4 inches to\ 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 
yoimg; 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 



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5 so BOTANY OF CROP IJLANTS 

regions of Asia, Europe, and America. It is not cultivated i 

in America to any great extent. 

Vacciniiun 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. 

HUCEXEBERIUES Ain> 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 (F. corymbosunij and V. atrococcum), 
and low-bush blueberries (F. canadense, F. angusHfolium, 
V, nigrum, and F. vacillans). 

The common black huckleberry on the market is Gaylus- 
sacia resinosa, Vaccinium angusHfolium is a rather common 
low-bush blueberry, while F. 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. 



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CHAPTER XXXVI 
OLEACE^ (OUve Fanuly) 

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 is four-lobed, sometimes entirely 
absent; the regular corolla is four-parted, or of four distinct 
petals, or absent. There are two stamenSy 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 fruit 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 oUve {Olea europma). 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 oUve 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. The flowers 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 purpUsh drupe. 



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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 europoea). Branch and fniit. {From Calif. Agr. 
Exp. Sta.) 



the warm, dry portions of California. The olive requires a 
mean annual temperature of S7°F., and it is claimed that at 
no time should the temperature go below i4°F. 



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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 oUve 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 trtmks, of yoimg or old limbs, 
and even of knaurs, Knaurs are knots or excrescences formed 
upon the trtmks 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 "stuflfed." 
Olive oil is an important commercial product. The best 
quaUty of oUve 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 "olive 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. 



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CHAPTER XXXVII 

CONVOLVULACEiE (Morning Glory Fanuly) 

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 (Ipomcea pan- 
durata)y used as food by the 
Indians, moon-flower {Ipomcea 
bona-nox) , morning glory 
{Ipomasa purpurea) , cypress vine 
{Quamodii quamoclit) and the 
bindweeds {Convolvtdus 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- 

FiG. 228. — Flower of sweet 

potato (I pomoea batatas), length- natc, exstipulate, entire, den- 

wise section. (After Sargent.) ^^^^^ ^^^^^^ ^^ dissectcd. 

Inflorescence and Flowers. — The flowers are in an axil- 
lary cyme, or sometimes solitary. 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 limb (Fig. 228). The five stamens are inserted on the 

554 



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CONVOLVULACEiE 555 

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 imequal. The anthers are two-celled, and 
longitudinally dehiscent. The ovary is sxiperior 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. 
Fruit. — The fruit is a capsule; its seeds are endospermous. 

Key to Important Genera 

Stigmas capitate (knob-like). 

Stamens and style exserted, QuamoclU. 

Stamens and style included, Ipomosa. 
Stigmas two, filiform or oblong, Convolvtdus, 

IPOMCtA BATATAS (Sweet Potato) 

Roots and Stems. — The sweet potato is a sinistrorse-twin- 
ing, trailing, 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. — In 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, petiolate, 
dark green, and glossy. 

Inflorescence and Flowers.^The large, purple, con- 
spicuous flowers are axillary, soUtary or cymose. The 



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5S6 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 family (Dioscoreaceae), closely related to lilies. This is a tall 
climbing plant with simple cordate, shining leaves, small, white flowers, and 
large tubers. 

Types 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 fleshjis watery, rich 
in sugar, soft and gelatinous when cooked. They are the 
sorts most in demand in the South. Common southern 



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CONVOLVULACE^ 



557 



sorts ("yams") are Triumph, Nancy Hall, Dooley Yam, 
Vineless Yam, Sugar, Southern Queen, Florida. 




Fig. 229. — Types of sweet potatoes (Ipomoea batatas) . A, Black Spanish ; 
B. Shanghai; C, Big Stem Jersey; D, Red Bermuda; E, Southern Queen. 
{Modified after Corbelt.) 




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 either 



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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 
com meal in its chemical composition. 

References 

Groth, B. H. a.: The sweet potato. Contrib. Bot. Lab. Univ. of Pa., 4- 
1-104, 1911. 



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CHAPTER XXXVIII 
SOLANACE^ (Potato Famfly) 

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. 

Ireaves — 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 imited lobes. The corolla is sympetalous, mostly 
fiveobed. The corolla varies considerably in shape: rotate 
(tomato), bell-shaped {Phy salts), fimnel-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 



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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. 232), Solatium (potato and 

eggplant). 
Anthers opening longitudinally 
Flowers white, Capsicum (pepper). 
Flowers yellow, Lycopersicon (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 5. nigrum, 
the black nightshade, and the common potato, etc.), or 
cUmbing herbs (5. 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. 

Lifiorescence, and Flowers. — The inflorescence is cymose 
(bittersweet), umbellate (black nightshade), racemose (5. 
carolinense, horse nettle), or rarely paniculate. The flowers 
(Fig. 232) are perfect and regular; in color, they are white 
(S. tuberosum varieties and 5. nigrum), blue (5. ceagni- 
folium, silver-leaved nightshade, and 5. tuberosum varieties), 



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SOLAN ACEiE $6 1 

yellow (5. rostratum, sand bur), or purple (5. dulcamara). 
The calyx is bell-shaped or rotate, generally five-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 (5. 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. muricatum (pepino, melon 
pear). 
Fruit a small, spherical berry, not over i inch in diameter. 

Peduncles ne- to three-flowered; ripe berries green, S. Iriflorum 

(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, S. carolinense 

(horse-nettle). 
Flowers purplish; fruit large, 5. melongena (egg pdant). 
36 



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S62 BOTANY OF CROP' PLANTS 

Berry enclosed by calyx, S. rosiratum (sand bur, buffalo bur). 
Tuber-bearing.* 

* Note. — Berthault in his monograph on the tuber-bearing SolanumSy has a 
key to 37 species. A portion of this key is here included (modified) to show 
the relation of common potato to some wild tuber-bearing specias. 
Corolla rotate. 
Points of sepals long and tapering. 
Leaves oval, S. 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. commersonil, 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, EngUsh, 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 foUage-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 



4 



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SOLANACEiE 563 

becomes spreading later. It is smooth and generally solid. 
It has no ribs at first, but as it develops, ijt becomes more or 
less quadrangular. 
Ireaves. — Potato leaves are compound pinnate, with more 



Fig. 231. — Flowering branch of potato (Solanum tuberosum). 

or less petioled 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- 



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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 pinna tifid. 

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. 



Fig. 232. — Potato (Solanum tuberosum). Ay berry; B, flower in median 
lengthwise section; C, floral diagram. 

It is white, yellow, purple, or blue in color and i to iH 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 



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SOLANACEJE 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 nimierous 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 foimd 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, split 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-fertilization 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 



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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 seeds are produced. Fitch found no seeds in 650 
seed balls of Early Rose. One seed ball from a Pearl crossed 
with a Rual 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 familiar 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 % cluster, and lateral, sectional and 
basal views. (After Stuart, U. S. Dept. of Agri.) 



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567 



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S68 



BOTANY OF CROP PLANTS 




JJk _Jrqund line 



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 foliage 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, 




loung 
tuber 



Fig. 234. — Young potato plant grown 
from seed. {After Percival.) 



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SOLANACEiE 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 5. 
commersoniiy 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 oflF the 
downward movement of elaborated foods from the leaves to 
the imderground 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 
Rhizodonia. 

Fungus Theory of Tuberization. — In general, it is found 
that darkness and low temperature favor the development 
of potato tubers. Tuberization is also faciUtated 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. 



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570 BOTANY OF CROP PLANTS 

When the potato was first 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 diflSiculty 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 imreasonable 
to suppose that the r61e 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 



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SOLANACE.E 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 Solatium^ 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 



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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" 




Fig. 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): 

I. Periderm or skin. 

2*. Cortex. 

3. Vascular ring. 



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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: 

Per cent. 

Skin (average of two varieties) 8 . 79 

Cortex (average of two varieties) 36 . 19 

External medulla (average of five varieties) ... 34. 17 
Internal medulla (average of five varieties) 14-95 



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. 

(a) Cortex. 

1. External. 

2. Internal. 

(b) Medulla. 

1. External. 

2. Internal. 



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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 quality 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. 



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SOLANACEiE 575 

Vascular Ring. — The vascular ring consists of a 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 
parench)ana, 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 quality. 
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. 

Medulla. — 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 light, 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. 



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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 
quaUty 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 foimd 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, 



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SOLANACE^ 577 

white-fleshed tubers are the only ones accepted in American 
markets. Yellow flesh is correlated with a strong flavor and 
a poor quahty, 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 quality, however. In this coim- 
try, these varieties are considered of good quaUty for the 
making of salads and for frying. 

Eyes (Fig. 236). — The buds of the potato tuber usually 
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 yoimg, but later disappears. The ''eye 
brow" ("eye yoke") is the line above the depression — the 
line which separates the leaf from the stem. In reality, the 
eye is a lateral branch with undeveloped intemodes, 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 Jonger. 

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 



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578 BOTANY OF CROP PLANTS 

the only one to develop. The sprout produced by 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 
Ukely 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 quality, 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 imdergo 
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 Jstarch 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 
Ught 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 



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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 



Cornell 

Maine 

U. S. all sources 

France: 

Coudon and Boussard. 

Coudon and Boussard. 

Coudon and Boussard. 

Coudon and Boussard. 



No. of No. 9f 
i analyses varieties 



43 
i6 

136 

7 
8 

7 
12 



7 
8 

7 
12 



Protein I Starch 



1.899 
2.170 

2. 200 

2.676 
2. 411 

2.365 
2.090 



17.356 
18.037 
18.400 

11.798 
13-218 
14. 118 
16.047 



Quality 

Very good. 
Very good. 



Very good. 
Good. 
Passable. 
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: 



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58o 



BOTANY OF CROP PLANTS 



Variety 


Zone 


Dry 
matter, 
per cent. 


Total N. 

fresh basis, 

per cent. 


Total N. 
dry basis, 
per cent. 


Rural 


Cortical 
Outer Med. 
Inner Med. 

Cortical 
Outer Med. 
Inner Med. 


20.95 

. 18.46 

14.04 

22.20 
19.41 
14.92 


0.46 
0.47 
0.45 

0.49 
0.51 
0.52 


2. 20 


New Yorker 

No. 2 


2.56 
3-23 

2.23 
2.63 
3-49 


Carman No. 3 



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 foimd 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. 



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SOLANACEiE 58 1 

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 utilized 
in the manufacture of alcohol. 

"Mealiness.*' — In estimating cooking quality of potatoes, 
mealiness 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 suifficient 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 insuifficient 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 Ukely 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 meahness can be expected in the boiled tubers, a 
condition necessary for high table quality in America. 

Quality of Potatoes. — The standards for table quaUty 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 



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S82 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 like 
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 amoimt as possible of cor- 
tical and outer medullary layers in proportion to inner med- 
ullary layer, should be of the finest quality." 

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 storedup 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 ''ruii 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- 



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SOLANACEiE 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 Delame, 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 



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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 So^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 19 14. 

disease, the tubers are of better quality 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 



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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 rim over tables, 
similar to those used in the purification of com 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 1912 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 Michigan. 

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 solitary 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 



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586 BOTANY OF 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 



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SOLANACEiE $87 

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. 5. 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 
(Z. esculentum var. validum), have a low, stiff, and erect 
growth form. L. esculentum var. grandifolium is a tall sort 
with a few large, entire leaflets. In the currant tomato (L. 
pimpinellifolium), and cherry tomato (L. cerasiforme) , the 
branches are usually weak and even traiUng 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 seedlings 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 are not injured beyond recovery, and it ap- 



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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-pinnate, and petioled. In all tomatoes except 
Zr. esculentum var. grandifolium and possibly i. pimpinelli- 
foliumy 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 stamen^ (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 possibiUty 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. 



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SOLANACEiE 589 

Extensive experiments made by Fletcher and Gregg with 
greenhouse or forced tomatoes showed that self-fertilized 
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 imcommon 
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. — Mimson has foimd, 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 amoimts of pollen: one abun- 
dant pollen, the other 10 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 insufficient supply 
of pollen. 

The Mature Fruit.— The fruit is a true berry (Fig. 240). 
The wild form of our common garden tomato (5. 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. 



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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 Lycopersicum; 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 Lycopersicum: L. esculentum, 
the common tomato, and L, pimpinellifoliumy the currant 
tomato. L. esculentum is, according to Bailey, divided into 
the following varieties : 

1. L. esculentum var. 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. 



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SOLANACE-ffi 591 

cerasiforme, L. pyriforme, and L, esculentum, including under 
the last the varieties vulgare, validum, and grandifolium. 

The above types of tomatoes may be artificially distin- 
guished by the following key; in all instances cultivated forms 
are imderstood. 

Key to Types of Cultivated Tomatoes 

Fruit in long racemes or branched clusters; berries red, currant-like, Currant, 

German J raisin or grape tomato. 
Fruit in short racemes or branched clusters. 
Plants low, stifif, and erect, having much the appearance of a potato plant; 

leaves small, curled, Upright tomato. 
Plant!s 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 pairs 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 }i to ^ 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 imdergone 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 



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592 BOTANY OF CROP PLANTS 

(var. grandifolium) J 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 pubescens) and the 
strawberry tomato (Physalis pubescens and P. alkekengi) are distinguished 
from Lycopersicum spp. in that the caljrx 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 betacea), a tropical plant, has a fruit similar 
in taste, at least, to that of the common tomato. This plant also belongs to 
the Solanaces, but may be distinguished from Lycopersicum by its woody 
habit of growth. 

History. — The tomato is still foimd 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 



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SOLANACE^ 



593 



ovate and entire. The flowers (Fig. 241) are solitary, or 
in twos or threes. The calyx is five-lobed, truncate, obcon- 
ical, cup-shaped or funnel- 
form. The corolla is white, 
rotate, usually five-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 hbes 
^stamen 
-cal^x lobe 

Z- celled 
ovary 



Fig. 241. — Median longitudinal 
section of pepper flower (Capsicum 
annuum). X 2. 



There 



Fig. 242. — Cross and lengthwise sections of the fruit of pepper (Capsicum 

annuum). 

38 



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594 



BOTANY OF CROP PLANTS 



Geogra];ihical. — ^This species has never been found wild. But it is quite well 
established that the entire genus Capsicum had its origin in tropical America. 




Fig. 243. — Fruits of peppers (Capsicum annuum). A, Oxheart (C. 
annuum cerasif orme) ; B, Cherry (C. annuum cerasifera) ; C, Celestial (C. an- 
nuum abbreviatum) ; I>, Chilli (C. annuum actiminatum) ; E, Long Cayenne 
(C. annuum acuminatum); F, Long Yellow (C. annuum longum); G, tabasca 
(C. annuum conoides); H, Sweet Spanish (C. annuum grossum) ; J, Ruby 
King (C. annuum grossum); 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 



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SOLANACE^ 595 

produce a full crop before frost, except in the Southern States, unless started 
under glass. 

Odier Species. — ^The only other species of Capsicum of any importance is 
C. frutescens. 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 t}T)es 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 i}4 inches long; peduncles about as long or longer, 
C. annuum conoides (Coral Gem, Tabasco, Cayenne, Orange-red 
Cluster). 
Fruit usually more than i J^ inches long; peduncles shorter. 
Leaves and fruit fascicled; fruit erect, C. annuum fasciculatum (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 Redj County Fair, Cardinal, 
Long Yellow, Ivory Tusk). 
Fruit oblate or oblong, truncated, deeply lobed, furrowed and wrinkled; flesh 
™ild, K 2 to ^^ inch thick, C. annuum grossum (Monstrous, Sweet Spanish,. 
Bell, Sweet Mountain, Golden Dawn, Ruby King, Brazilian Upright, 
Golden Upright, Squash). 
Fruit subcorneal, ovate or elliptical, slightly longer than broad, % to 2 inches 
long; calyx not embracing base, C. annuum abbreviatum (Celestial, Etna, 
Kaleidoscope, Red Wrinkled, Princess of Wales). 
Fruit generally smooth, oval, spherical, cherry or heart-shaped, ^i to i}4 
inches in diameter; calyx seated on the base, C. annuum cerasiforme 
(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 peppers (Coral Gem, Tabasco, Chilli, Cayenne 



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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 ungroimd 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 groimd 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. glatcca and N, tomentosa) grow to a 
height of lo 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 N. 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, purplish, 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 limb. There are five 



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SOLANACEJS 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 spHts 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. tahacum (tobacco) is the only one of great commer- 
cial importance. 

NICOTIANA TABACUM (Tobacco) 

Habity Roots, Stems.— The common 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 
flower stalks, so that a considerable portion of the food supply 
which would normally go to flower and fruit production may 
be directed to leaf growth. 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 



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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 Leaves. — ^' 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. The flowers (Fig. 244) are about 2 inches long, and 
pink, yellow, 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- 



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SOLANACE^ 



599 



cence. That the tobacco plant 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). A, flower; B, pistil; C, corolla 
cut open and spread out flat; D, cross-section of young fruit; E, lengthwise 
section of young fruit. {After Strasburger.) 

Fruit. — Tht fruit (Fig. 244) is a two- to four-valved cap- 
sule, bearing numerous small seeds. A single plant may 
produce as many as a miUion 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. 



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600 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. rustica 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 Dubolsia hopwoddii, a species of SolanacecB. "Indian" 
or "wild tobacco" is a name often given to Lobelia inflatay the dried leaves 
and tops of which are oflScinal. It is a member of the bellflower family, 
CampantdacecR. 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. 

T^rpes 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 snuff. 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 coimtry different from 
the cigar types. The physical and chemical properties of 
the soil have a marked influence on the quality 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 



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SOLANACE^ 6oi 

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 



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6o2 



BOTANY OF 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 



Kentucky 

North Carolina. 

Virginia 

Ohio 

Tennessee 

Pennsylvania 

South Carolina. . 

Wisconsin 

Connecticut 

Maryland 

All other States 
United States 



Acres 



440,000 

320,000 

192,500 

93,700 

92,900 

31,400 

65,000 

41,000 

22,200 

22,000 

47,700 

1,368,400 



Pounds 



356,400,000 

198,400,000 

144,375,000 

84,330,000 

69,675,000 

42,390,000 

37,700,000 

36,900,000 

29,907,000 

16,280,000 

44,030,000 

1,060,387,000 



Farm value 
Dec. I, 
dollars 



23,799,000 

22,221,000 

13,571,000 

7,590,000 

4,990,000 

3,900,000 

2,639,000 

2,214,000 

3,095,000 

1,384,000 

12,638,000 

96,041,000 



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6o4 BOTANY OF CROP PLANTS 

The United States leads all other countries in the produc- 
tion of tobacco. In 1914, Japan ranked second to the 
United States, but its output was only about 10 per cent, of 
that in this country. 

References 

Appleman, C. O.: Physiological Behavior of Enzymes and Carbohydrate 
Transformations in After-ripening of the Potato Tuber. Bot. Gaz., 52: 

306-315, 1911- 
Barnes, J. : The Potato (Solanum Tuberosum) : Its History, Microscopical 

Characters, and Structure. Ann. Rep. Trans. North Staffordshire Field, 

cl, 1902-03, pp. 96-106. 
Bernard, Noel: Sur la tuberculization de la pomme de terre. Compt. 

Rend. Acad. Sci. (Paris), 132: 3S5-3S7i iQoi- 
Berthault, Pierre: Recherches botaniques sur les varieties cultivees du 

Solanum tuberosum et les.especes sauvages de Solanum tuberiferes voisins. 

Ann. Sci. Agron., 28: 1-59, 87-143, 173-216, 248-291, Paris, 1911. 
Fitch, C. L.: Productiveness and Degeneracy of the Irish Potato. Colo. 

Agr. Exp. Sta. Bull. 176: 1-16, 19 10. 
Indentification of Potato Varieties. la. Agr. Ext. Dept. Bull. 20: 1-32, 

194. 
Fletcher, S. W., and Gregg, O. I.: Pollination of Forced Tomatoes. Mich. 

Agr. Exp. Sta. Spec. Bull. 39: 2-10, 1907. 
Pollination of Forced Tomatoes. Mich. Agr. Exp. Sta. Spec. Bull. 39: 

294-301, 1907. 
Gable, C. H.: The Wild Tomato. Jour. Hered., 6: 242, 191 5. 
GiLMORE, John W.: Quality in Potatoes. Cornell Agr. Exp. Sta. Bull. 230: 

503-525, 1905. 
GooDSPEED, T. H.: Parthenogenesis, Parthenocarpy and Phenospermy in 

Nicotiana. Univ. Calif. Pub. Bot., 5: 249-272, 1915. 
Halstead, B. B.: Notes upon Stamens of Solanaceae. Bot. Gaz., 15: 103- 

106, 1890. 
Heckel, E.: Sur Torigine de la pomme de terre cultivee et sur les mutations 

gemmaires culturales des Solanum tuberiferes sauvages. Ann. Fac. Sc. 

Marseille, 1907, 82 pp. 
Irish, H. C. : A Revision of the Genus Capsicum with Especial Reference to 

Garden Varieties. 9th Ann. Rep. Mo. Bot. Gard., 53-110, 1898. 
Jones, Donald F.: Natural Cross-pollination in the Tomato. Science, n. s., 

43: 509-510, 1916. 
Klemt, F.: tJber den Bau und die Entwickelung der Solanaceenfruchte. 

Berlin, 1907. 



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SOLANACEiE 605 

Magrou, H.: Symbiosis and Tuberization in Potato. Compt. Rend. Acad. 

Sci. (Paris), 158; So-S3» i9i4- 
MiDDLETON, R. Morton: Solanum Tuberosum L., and Its Allies. Jour. 

Bot., 47: 228, 1909. 
Reed, T.: The Anatomy of Some Tubers. Ann. Bot., 24: 537-548, 19 10 

(Potato and Jerusalem artichoke). 
Rendle, a. B.: Production of Tubers within the Potato. Jour. Bot., 31: 

193-195, 1893- 
RiGDWAY, Charles S. : Grain of the Tobacco Leaf. Journ. Agri. Research, 

7: 269r-288, 1916. 
Stewart, F. C: Observation on Some Degenerate Strains of Potatoes. 

N. Y. Agr. Exp. Sta. Bull. 422: 319-357, 1916. 
Stuart, William: Group Classification and Varietal Descriptions of Some 

American Potatoes. U. S. Dept. Agr. Bull. 176: 1-56, 191 5. 
WiTTMACK, L.: Die Stammpflanze unserer Kartoffel. Landw. Jahrb., 38: 

551-605, 1909. 
Studien iiber die Stammpflanze der Kartoflfel. Ber. Bot. Gesell., 27: 28- 

42, 1909. 



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CHAPTER XXXIX 
CUCXJRBITACEiE (Gourd Family) 

There are about 650 species of cucurbits, mainly in tropical 
regions. All cultivated cucurbits are easily injured by 
frost, and are distinctly warm season crops. 

A number of species are of economic importance. Chief of 
these are the pumpkin, squash, watermelon, muskmelon, and 
cucumber. The wild cucumber {EchinocysHs lobata) and 
the star cucumber {Sicyos ,angulatus) are sometimes planted 
as ornamental vines. The squirting cucumber {Echallium 
elaterium) is a fleshy herb containing a cathartic and poison- 
ous principle, elaterin, the main ingredient of elaterium. 

Habit. — The members of this family are commonly known 
as *' cucurbits." The majority of them are annual, climbing 
or trailing herbs, with tendrils, but often reaching a large 
size. 

Stems and Leaves. — The stems are hollow and usually 
covered with stiff hairs. The leaves are large, alternate, 
petioled, heart-shaped, palmately lobed or dissected. The 
tendrils arise as a rule in the axils of leaves. The same ten- 
dril may be dextrorse and sinistrorse at different points along 
its axis and may be simple or forked. 

Flowers. — The flowers (Figs. 246 and 247) are axillary, 
either solitary, paniculate, or rarely racemose or subumbel- 
late. They are monoecious or dioecious, commonly white or 
yellow, rarely blue or red. The calyx forms a tube which is 
adnate to the inferior ovary; its limb is tubular or campanu- 

606 



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CUCURBITACE^ 607 

late, and usually has five imbricated lobes. The corolla is five- 
lobed, usually sympetalous, sometimes parted to the base, in- 
serted on the limb of the calyx, and rotate or campanulate. 
The stamens (Fig. 247) are five in number, but they often grow 



Fig. 246. — Field pumpkin (Cucurbita pepo). A, staminate flower; B, pistil- 
late flower. 

together so that there are apparently three. In case there 
are three stamens, two of them are broader than the third; 
the two broad stamens have two-celled anthers, the other has 
a one-celled anther, thus making in all five anther cells to the 
androecium. The filaments are short, often united, and 



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6o8 BOTANY OF CROP PLANTS 

tipped by the worm-like pollen sacs. The ovary (Fig. 248) is 
inferior, one- to three-celled, and usually has numerous seeds 
in each cell or locule; the style is terminal, simple or lobed. 
Fruit. — The fruit is a pepo, usually indehiscent, or in some 



Fig. 247. — Field pumpkin (Cucurbita pepo). A, pistillate flower; B, stami- 
nate flower; both with perianth removed. 

cases (MicrampeliSy Cyclanthera) dehiscent at the apex or 
bursting irregularly. In many instances (watermelon, 
pumpkin, squash), the fruit is of enormous size. The outer 
part of the fruit is receptacle which has become attached to 
the exocarp. The flesh of the fruit is chiefly mesocarp and 



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CUCURBITACE^ 609 

)lacenta 
seeds 



Fig. 248. — Cross-section of mature fruit of cucumber (Cucumis sativus). 



Fig. 249. — Germination of pumpkin (Big Tom) seeds/ showing the 
pegs functioning in the removal of the coats. {After Crocker, Knight and 
Roberts.) 



39 



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6lO BOTANY OF CROP PLANTS 

« 

endocarp. Seeds are usually abundant, flat, and without 
endosperm. 

Germination of Cucurbit Seeds. — The cotyledons are 
epigean in all the common members of the Cucurbitaceae. 
There are a few hypogean forms, such as Megarhiza calif arnica 
and Sicyosperma gracilis. The first portion of the seedling to 
appear above ground is the hypocotyl, which emerges as an 
arch (Fig. 249). At the base of the hypocotyledonary arch, 
there is developed a peculiar outgrowth known as the "/>^g." 
It is a natural part of the plant, and although it varies some- 
what in size in [different cucurbits, it has been shown that 
gravity has no direct effect in increasing peg development 
or in determining its lateral placement on the hypocotyl. 
The peg serves to hold the seed coat while the hypocotyl 
withdraws the cotyledons from the coat. It will be noticed 
(Fig. 249) that one edge of the seed coat is caught against the 

peg. 

Key to Principal Genera 

CoroUa rotate or campanulate, five-parted to or almost to the base. 

Tendrils often two to three times branched, CUrtdlus (watermelon, citron). 

Tendrils simple, Cucumis (muskmelon, cantaloupe, cucumber). 
Corolla campanulate,^ five-lobed to or little below middle CucurhUa (gourd 

pumpkin, squash). 

CUCUKBITA (Squash, Pumpkin, Gourd) 

StemS| Leaves, Flowers. — Members of this genus are 
annual, prostrate bushy or trailing vines with rough stems 
which have a tendency to root at the nodes. The tendency is 
particularly marked in the long-running varieties of squashes 
(Turban, Marblehead, Canada Crookneck, Field Pumpkin). 
The tendrils are branched. The leaves are usually cordate 
at the base, lobed (C pepo), or not lobed (C. maxima). 
The flowers are always solitary in the axils of the leaves, 
yellow, and monoecious. In squashes with a bushy habit 



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CUCURBlTAgSiE 6ll 

(early squashes)^ the stamina te flowers are on long peduncles, 
while th€ pistillate flowers occur near the base of the plant 
on comparatively short peduncles. In the long-running 
squashes (fall and winter types), the stamina te flowers are 
borne near the center of the plant on long peduncles, while 
the pistillate occur some distance from the roots, on compara- 
tively short stalks. The flower stalks (peduncles) may be 
strongly ridged (as in C pepo and C, moschata) or compara- 
tively smooth (as in C. maxima) . In the staminate flowers, the 
calyx tube and corolla are campanula te and five-lobed; the 
stamens are three in number, inserted on the calyx tube, the 
filaments are free, and the anthers large, linear, and more 
or less united; the ovary is rudimentary. In the pistillate 
flowers, the calyx and corolla are as described above; the 
stamens are rudimentary (three sta«iinodia commonly 
present), pistil one, ovary oblong with three to five many- 
ovuled placentae, style short and thick, and stigmas three to 
five, each two-lobed and papillose. There are always many 
more staminate flowers produced than pistillate. 

Pollination and Fertilization. — The squashes and pump- 
kins are usually insect-pollinated. It has been shown that 
the varieties of C pepo, including the common Crookneck, 
Scallop, and Pineapple squashes, and the common field 
pumpkin, will readily cross with one another. However, the 
above will not cross with varieties of C. maxima, including 
Hubbard, Marblehead, Turbans, and Mammoth Chili and 
Valparaiso pumpkins. These latter will cross with one 
another. Varieties of C. moschata will not cross with either 
of the above species. Cucurbita species do not cross with 
melons and cucumbers. Squashes and pumpkins ordinarily 
do not reach any considerable size unless the ovules are 
fertilized. 

Mature Fruit. — The mature fruit is a pepo. In the 



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6l2 



BOTANY OF CROP PLANTS 



Turban squashes, the receptacle does not extend over the 
top of the ovary, while in most other sorts, it is entirely 
closed at the top. The pericarp is fleshy. 





Fig. 250. — i4, cross-section of squash (Cucurbita maxima) fruit stalk; B, 
same of pumpkin (Cucurbita pepo). 

Geographical. — The genus Cucurbita has about 10 species, natives of trop- 
ical America, Asia, and Africa. 



Key to Important Species of Cucurbita 

Leaves lobed; stalks of fruit strongly ridged (Fig. 250, B). 

Calyx lobes narrow, peduncle not enlarged next to the fruit (Fig. 251, B) 




Fig. 251. — A, fruit stalk of Cucurbita maxima; B, of C. pepo; C, of C. mos- 
chata. {After Bailey.) 

Cucurbita pepo (pumpkin, scallop, gourd). 
Calyx lobes broad, peduncle much enlarged next to the fruit (Fig. 251, C), 
C. moschata (Canada Crookneck and Cushaw). 
Leaves not lobed; stalks of fruit not prominently ridged (Fig. 250, A), Cucur- 
bita maxima (Marblehead, Turban, Hubbard squashes, etc.). 



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CUCURBIT ACE.E 613 

CUCURBITA PEPO 

Description. — This is an annual species, with long, running 
stems; in the so-called "bush-pumpkins," which include the 
scallops (patty-pans or C5anblings) and summer or crookneck 
squashes, the plants are more compact. The leaves are 
three- to five-lobed. The calyx lobes are narrow. The 
peduncle is not enlarged next to the fruit. The fruit varies 
much in size and shape. 

Origin. — ^There is a question as to the origin of the pump- 
kin. It is considered by some to be of American origin, as 
it was cultivated by the Indians at the time America was 
discovered. However, it is claimed by others that its original 
home is southern Asia. 

Types and Varieties. — Cucurbita pepo includes the follow- 
ing groups: 

Plants with long, running stems, True field pumpkins (Connecticut field and 
Mammoth are common varieties). • 

Some of the vegetable marrows have long, running stems, while others 
have a bushy habit. As a group they are relatively unimportant. 

Plants bushy, Summer squashes^ crooknecks. In these the neck is decidedly 
crooked and narrow, the distal end is swollen but terminating in a point, 
the skin is orange-colored and covered with many round excrescences. 
Scallop or patty-pan varieties. These are also known as custard marrows, 
and in the South as cymblings. The leaves are large, entire, and very 
slightly five-lobed; the fruit is much broader than long, the edge coarsely 
scalloped; the flesh is solid and floury; the skin is smooth and of various 
colors. The pineapple summer squashes are oblong-conical varieties. 

Plants with slender, running stems; leaves lobed; fruit small, hard, not edible, 
of various shapes, Gourds (in part) (C pepo var. ovifera). 

Not all ''gourds" belong to the species Cucurbita pepo. 
In addition to this species, they are also referred to Lagenaria 
vulgaris, Luffa, Cucumis dipsaceus, Cucumis anguria, and 
Benincasa cerifera. 



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6 14 BOTANY OF CROP PLANTS 

CUCUKBITA MAXIBIA 

Description. — This is an annual plant with long, running, 
cylindrical, somewhat prickly (not spiny) and hairy stems. 
The leaves are large, not lobed, except on young shoots. The 
peduncles are smooth, i.e., not ridged. The calyx tube is 
not ribbed. The corolla tube is of equal diameter through- 
out, the lobes curved outward. The fruit varies in shape 
and size, but unlike representatives of the preceding species, 
it never has a light color or a crookneck or bears warty ex- 
crescences; the peduncle is not much enlarged next to the 
fruit. 

It is quite agreed that this species is of American origin. 

Tjrpe and Varieties. — Representatives of the species C. 
maxima are late maturing, as a rule, and hence are quite 
generally known as "winter squashes.'' The principal types 
are as follows: 

1. Turban Squashes. — The fruit has the appearance of a 
turban or '*Turk's-c^p." This is due to the failure of the 
fleshy receptacle to completely cover over the ovary, and 
hence the latter protrudes, forming a fruit the character of 
which suggests the expression '* squash within squash." 

2. Hubbard Squashes. — These are the most popular 
squashes in the Northern States. They are broadly pear- 
shaped, or olive-shaped with very thick, hard, dark green 
skin and dark yellow, floury flesh. There are varieties of 
the Hubbard (Red or Golden Hubbard) with orange-red skin. 

3. Marblehead Squashes. — These have a gray skin. Other- 
wise they resemble the Hubbard squashes. 

4. Marrow Squashes. — There are a number of varieties of 
these, only a few of which are very well known. Most of 
them have a smooth skin and a very floury flesh. The 
Boston Marrow, a variety with orange-colored skin and flesh, 
is the best known in the United States. 



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CUCURBITACE/E 615 

5. Mammoth Pumpkins and Squashes. — These are the 
largest of the squashes. Some varieties (Mammoth Whale 
squash, Valparaiso squash, Mammoth pumpkin) attain a 
diameter of i to 2 feet and a weight of 100 to 200 pounds. 
The Mammoth pumpkins are strongly flattened at the ends, 
while the mammoth squashes are longer than broad, and 
oblong or narrowly oval in shape. 

CUCURBITA MOSCHATA 

Description. — This is an annual with long, running, hairy 
(never spiny) stems which readily root at the nodes. The 
leaves are lobed, dark green and with whitish blotches here 
and there. It is said that these whitish areas are due to a 
thin layer of air beneath the epidermis. The calyx is deeply 
lobed. The corolla widens upward. The peduncle is 
angular, deeply ridged, and swollen where it joins the fruit. 
The flesh of the fruit usually has a musky flavor. 

The species is said to have originated in Eastern Asia. 

Types. — The principal types belonging to this species are : 

1. Canada Crookneck or Winter Gourd. — The plants are 
small; the fruit is also rather small, smooth and crook- 
necked. 

2. Cushaw. — This is the "pie pumpkin" or squash of the 
South and Southwest. It is a crook-necked type of squash, 
the skin of which may be white, yellow, or striped. 

CUCUMIS (Muskmelon, Cantaloupe, Cucumber) 

StemS| Leaves, Flowers. — All of our common species are 
hispid or rough, trailing, annual herbs. The tendrils are 
simple. The leaves are simple, palmately three- to five-lobed 
or dissected. The flowers are monoecious. Rane finds that 
some varieties of muskmelons possess perfect flowers. For 



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6i6 



BOTANY OF CROP PLANTS 



example, out of 95 varieties examined, 85 had perfect 
flowers, and only 1 1 had imperfect flowers. 

The staminate flowers are in small clusters, or rarely soli- 
tary. The calyx tube is turbinate or campanulate, and its 
limb five-lobed. The corolla is campanulate, deeply five- 
lobed or five-parted, the lobes acute. The three stamens are 




Fig. 252. — Leaves of A, cucumber (Cucumis sativus) and B, muskmelon 
(Cucumis melo). X M. 

separate, with short filaments and oblong anthers. The 
ovary is rudimentary. 

Pistillate flowers are solitary. The calyx and corolla are 
similar to those described above. The ovary is ovoid or 
globose, with three to five placentae; the style is single and 
short, the stigmas obtuse, three in number, and the ovxiles 
numerous. The fruit is a pepo varying in shape, size, sur- 
face characters, and physical and chemical composition. 

Pollination. — Grifiin gives data with reference to pollina- 
tion and fruiting of the cantaloupe. He kept an account of 



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CUCURBITACEJE 617 

the number of flowers produced on each of six vines, from 
June 27 to July 13, at which latter date the vines became 
indistinguishable from each other. His data are as follows: 

Number of flowers 
Date Staminate Pistillate 

June 27 203 I 

June 30 338 II 

July 3.; 474 28 

July 7 755 95 

July 10 660 87 

July 13 64s 31 

Total 3,07s 253 

Average to each vine 512 42 

Vines continue to bloom profusely until late in August in 
the locality (Rocky Ford, Colorado) where data were ob- 
tained. Here, melons may ripen that are set as late as the 
middle of August; it takes about six weeks for one to mature. 
Twenty ripe melons per vine is a good crop. In all Cucumis 
species, the staminate flowers are more numerous and appear 
earlier than the pistillate ones. Pollination is carried on by 
insects. Ordinarily, lack of fertilization causes a premature 
dropping of the fruit, and incomplete fertilization results in 
misshapen fruit. 

Geographical. — ^There are close to 30 species of CucumiSf most of them be- 
longing to tropical Asia, Africa, and the East Indies. 

Key to Principal Species 

Fruit smooth, not spiny or tuberculate at maturity, Cucumis tnelo (musk- 
melon, cantaloupe, melons). 
Fruit spiny or tuberculate at maturity. 
Stems (cultivated) 6 to 15 feet long; fruit 6 to 12 inches long, Cucumis 

sativus (cucumber). 
Stems 3 to 6 feet long; fruit i to i J-^ inches long, Cucumis anguria (prickly 
cucumber, West Indian gherkin, Jerusalem cucumber, gooseberry gourd). 



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6l8 BOTANY PF CROP PLANTS 

CUCUMIS MELO (Muskmekm, Cantaloupe, lUons) 

Description. — This is a hirsute or rough annual herb with 
prostrate stems. The leaves are subcordate, with somewhat 
rounded angles. The flowers are monoecious, or in some 
varieties the pistillate flowers are with stamens. The fruil 
varies in shape and size. 

Cucutnis melo is considered to be a native of southern Asia. 

Botanical Varieties of Cucumis melo. — Naudin has mono- 
graphed the species Cucumis melo, and according to him, it 
is divided into a number of botanical varieties, races, or 
groups which can be fertilized by each other. The principal 
ones are as follows: 

1. Netted Melons {Cucumis melo var. reticulatus) , — To this 
group belong the common muskmelons. These usually have 
a netted skin, sometimes almost smooth. All of them are 
shallow ribbed melons, the flesh of which may be green- or 
salmon- tin ted (Jenny Lind, Emerald Green, Netted Gem, 
Rust Resistant Pollock, Ironclad, Montreal Nutmeg, Cos- 
mopolitan, Ryan's Early Watters). The so-called "Rocky 
Ford Cantaloupes" are not true cantaloupes; the "Rocky 
Fords" include a number of varieties (chiefly Rust Resistant 
Pollock No. 25, Netted Gem), all of which are netted melons 
(var. reticulatus). 

2. Cantaloupes or Rockm^lons {Cucumis m^lo var. canta- 
lupensis). — The true cantaloupes are usually deep-ribbed, 
hard-rinded, and warty or scaly. The flesh is either green- 
or salmon-tinted (Hackensack, Nutmeg, Carmes, Long 
Yellow). 

3. Pineapple Melons {Cucumis melo var. saccharinus) . — 
These resemble the common netted melons. They are ob- 
long in shape and have a very tender flesh. 

4. Snake Melon or Snake Cucumber {Cucumis melo var. 
flexuosus). — The fruit of this is long and slender, bent and 



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CUCUKBITACEiE 619 

twisted, furrowed, and thickest at the distal end. It often 
reaches a length of 3 feet, and a diameter of i to 3 inches. 



Fig. 253. — I to 6, stages in the development of the cucumber fruit; the 
flower is unopen in i and 2, in 3 it is fully open, in 4 and 5 it is withering, and 
in 6 the perianth, stamens and styles have fallen from the enlarged ovary. 7, 
staminate flower of cucumber. 

5. Winter Melons {Cucumis melo var. inodorus), — Little 
known in United States. 



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620 BOTANY OF CROP PLANTS 

6. Cucumber Melon {Cucumis melo var, acidulus), — Of no 
economic importance. 

7. Orange Melon, Mango Melon, Melon Apple, Vine Peach, 
Garden Lemon, Vegetable Orange {Cucumis melo var. chito), — 
Used in making preserves. 

8. Dudaim Melon, Pomegranate Melon, Queen Anne^s 
Pocket Melon {Cucumis melo var. dudaim). — Inedible. 

CUCUMIS SATIVUS (Cucmnber) 

Descrq>tion. — This is an annual plant with rough, hispid 
stems which reach a length of 6 to 15 feet, and are somewhat 
branching. The leaves are subcordate, almost as wide as 
long, and somewhat five-lobed. The corolla is yellow. 
There is a general impression that the cucumber can be 
crossed with the melon. Experiments have shown that this 
crossing is impossible. The fruit is oblong, obscurely three- 
angled, tuberculate when young, but often becoming smooth 
(in cultivated forms) at maturity. 

Geographical. — Cucumbers have been in cultivation for 3,000 or 4,000 
years. They were first cultivated in Asia. The species has not been found 
growing wild. 

Closely Related Forms. — There are a number of "cucum- 
bers" which may be confused (at least in name) with the 
common cucumber {Cucumis sathus). Chief of these are 
the snake cucumber {Cucumis melo var. flexuosus), West 
Indian gherkin {Cucumis anguria), musk cucumber {Cucumis 
moschata), and star cucumber {Sicyos angulatus). The snake 
cucumber is in reality a melon. It is characterized by the 
long, narrow, twisted fruit. In the West Indian gherkin the 
stems are shorter and the fruit much smaller than those of 
the cucumber. It is a common practice to use young cucum- 
bers as gherkins. The musk cucumber is also a melon. The 



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CUCURBITACE^ 62 1 

star cucumber fruit is compressed, dry and membranous, and 
occurs in head-like clusters. 

Types. — There are three principal types of cucumbers 
{Cucumis sativus) : (i) Common field cucumbers; (2) English 
or forcing cucumbers (var. anglicus); and (3) Sikkim cucum- 
bers (var. Sikkimensis). The field cucumbers are divided 
into black spine varieties and white spine varieties, and these 
two divisions are further subdivided. 

The English or forcing cucumbers differ from the ordinary 
cucumbers. In the forcing-house, the former do not need 
artificial fertilization, while all our common cucumbers must 
be artificially fertilized. Hence, the English cucumbers have 
the habit of producing seedless fruit. The fruit of the 
forcing cucumber is long and smooth, green in color, and at 
first covered with a few black spines. Common varieties 
are Telegraph, Sion House, Kenyon, and Lome. The Sik- 
kim cucumber fruit is large and reddish brown, marked with 
yellow. 

Pickles. — The growing of cucumbers for pickling is an 
industry quite different from that having to do with the 
cultivation of cucumbers for slicing. The pickle industry is 
mostly restricted to the Northern States, as cucumbers for 
this industry do best in the cooler climate of the north. 
Cucumbers that are to be pickled are harvested before they 
reach maturity, and are not allowed to reach a length of 
more than about 5 inches. They are hauled to the local 
"salting station, '' where they are immersed in a brine, which 
is contained by large wooden tanks, some with a capacity of 
1,500 bushels. The pickles are kept in these tanks until 
ready to be bottled at the factory. 

Dill pickles are made either from pickles stored in brine 
or from fresh cucumbers from the vine. The peculiar 
flavor of dill pickles is secured by adding to the brine and 



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622 BOTANY OF CROP PLANTS 

cucumbers, the stems, leaves, flowering heads, and seeds of 
dill, and also, sometimes, a spice made from allspice, crushed 
black pepper, coriander seed, and bay leaves. Some 
vinegar is added in the later stages of the pickling process. 

CUCUMIS ANGURIA (Gherkin) 

Descrqition. — This is an annual, creeping, branching 
plant. The stems are slender, rough-hairy, and bear simple 
tendrils. The leaves a,Te deeply sinuate-lobed. Staminate 
flowers are small, numerous, and on short peduncles, while 
pistillate flowers are on long stalks. The fruit is about i)^ 
inches long, oval, prickly, and green with whitish streaks. 
The flesh is thin, and the seeds form a proportionately large 
percentage of the fruit. 

The species is native of the West India Islands. 

The genuine gherkins of commerce are the fruit of C 
anguria. Small cucumbers (C. sativus) are often substituted 
for them, however. 

CITRULLUS (Watenn^on, Citrcm, C<docynth) 

Descrq^tion. — Citrullus species are coarse, trailing herbs 
with branched tendrils. The leaves are rotimd-cordate, and 
three- to five-lobed. The flowers are monoecious, and always 
solitary. In the staminate flowers, the calyx has a broad 
campanulate tube and a five-lobed limb, and the corolla is 
five-parted to below the middle; there are three stamens with 
subsessile anthers, one of which is one-loculed, the other 
two, two-loculed. In the pistillate fl^rwers, the calyx and 
corolla are as described above. The ovary is ovoid with 
three fleshy placentae; the style is short, with three large 
stigmas, and ovules are numerous. The fruit varies widely 
in form and size, color and thickness of skin, flavor, etc. 



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CUCURBITACEiB 623 

Geographical. — ^There are two or three species of CUruUus, natives of the 
Mediterranean region, Africa, and Asia. The only one of agricultural im- 
portance is Citrullus vulgaris, which includes the watermelon and citron. 



CITRULLUS VULGARIS (Watennelon, Citron) 

Description. — The watennelon is a hairy annual with 
long, angular, somewhat branching stemsy which often 
attain a length of 15 feet. The leaves are lobed. The 
flowers are pale greenish-yellow. The fruit varies in shape 
and has a firm fleshy rind and a tender watery pulp, which 
is usually reddish in color and sometimes purplish, yellowish 
or white. The skin or rind varies in thickness from }i inch, 
in such varieties as White Gem, Gray Monarch, and Hoosier 
King, to I inch in the Black Spanish, Nabob, and Golden 
Gate. The weight of the fruit frequently reaches 23 or 25 
pounds. 

Geographical. — The watermelon is indigenous to tropical and South Africa. 
It has been cultivated for centuries; Egyptian paintings show that these 
peoples cultivated them. 

Tj^s and Varieties. — The varieties of Citrullus vulgaris 
may be divided into two general types: 

1. Common Watermelon, — Flesh of fruit comparatively 
tender and watery. 

2. Citron. — Flesh of fruit very firm. 'As compared with 
watermelons, the citron feels much more solid. The citron 
is used for making sweet pickles and preserves. It is not 
eaten in the raw state. The juice of the citron is added in 
equal parts to that of such fruits as peaches, cherries and 
others whose juices will not ''jell" by themselves to make 
them produce jelly. The citron has a large amount of 
pectin in the cell walls. This is the substance in fruits 
which causes their juice to "jell." 



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624 BOTANY OF CROP PLANTS 

The citron is not to be confused with the true citron {Citrus 
medico) (see page 480). 

Rane divides the varieties of watermelons into six 
"classes:" (i) light green (Light Icing, Gray Monarch); 
(2) medium green (Fordhook Early, Jackson); (3) dark 
green (Black Spanish, Mountain Sweet, Cannon Ball) ; (4) 
light-striped (Golden Gate, Delaware, Hoosier King, Rattle- 
snake, Santiago) ; (5) dull-striped (Price of (ieorgia. Orange, 
Triumph); and (6) mottled green (Nabob Phinney's Early). 
These "classes" are subdivided into "types" according to 
shape of fruit, and the "types" are each divided into two 
groups: those with light seeds, and those with dark (black 
6r brown) seeds. 

References 

CoRBETT, L. C: Cucumbers. U. S. Dept. Agr. Farmers' Bull. 254: 1-30, 

1906. 
Crocker, W., Knight, L. S., and Robert E.: The Peg of the Cucurbitaceae. 

Bot. Gaz., 50: 321-339, iQio- 
Grifpin, H. H.: The Cantaloupe. Colo. Agr. Exp. Sta. Bull. 62: 1-18, 1901. 
Pammel, L. H.: Crossing of Cucurbits. Bull. Torrey Bot. Club, 20: 358-359, 

1893. 
Results of Crossing Cucurbits. la. Agr. Exp. Sta. Bull. 23: 906-917, 1894. 
Rane, F. W.: Fertilization of the Muskmelon. Proc. Soc. Prom. Agr. Sci., 

150-151, 1898. 
II. Classification of Watermelons. N. H. Agr. Exp. Sta. Bull. 86: 95-107, 

1 901. 



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CHAPTER XL 

COMPOSITE (Thistle Family) 

The composite or thistle family is one of the largest of the 
plant kingdom, consisting of about 10,000 species in about 
760 genera; it has a wide geographical distribution. 

Representatives of the family are considered to be among 
the most complex of plants, and among Dicots, of the highest 
evolutionary rank. They show a combination of characters 
which place them high in the scale of evolution. These are: 
imion of petals (sympetaly), inferior ovary (epigyny), seed- 
like fruit, pappus, imited (syngenesious) anthers, head 
inflorescence, diclinism, and dimorphism. 

Comparatively few species of this large family are of 
economic value. The most important are common lettuce, 
Jerusalem artic)ioke, endive, salsify, and dandehon. The 
following is a short list of the less important representatives 
of the family: yarrow {Achillea) ^ Chrysanthemum j sage and 
wormwood (Artemisia spp.), sunflower (Helianthus)^ Arnica, 
Aster, goldenrod (Solidago), sow-thistle (Sonchus), Dahlia, 
marigold {Calendula), rabbit-brush {Chrysothamnus) , flea- 
bane {Erigeron), everlasting (Antennaria) , Spanish needles 
{Bidens), and thistle {Carduus). 

Habit. — This large family is made up mostly of herbaceous 
forms; there are a number of shrubs, however, and a few 
tropical tree species. Many of them, as the dandelion and 
lettuce, have a milky juice, while in others the sap is watery, 
resinous, acrid or bitter. 

Leaves. — The leaves are either alternate or opposite, 
rarely in whorls (verticillate), and usually without stipules. 
40 625 



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626 BOTANY OF CROP PLANTS 

Inflorescence. — The inflorescence (Fig. 254, A) is a head, 
the flowers, usually numerous, being mounted on a common 
receptacle which is subtended by an involucre. A "sun- 
flower" is not a single flower in the botanical sense, but a 
group or composite of individual flowers. The receptacle 



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. 



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COM^OSIT^ 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 
Liguliflorce and TubuliflorcB, 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 



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628 BOTANY OF CROP PLANTS 

be present or wanting. In the Tubuliflora, there are both 
disk and ligulate flowers, the former occupying the center 
of the head, while the ligulate ones are at the margin of the 
receptacle, and are called ray flowers. In the Tubiliflor(e, the 
ray or ligulate flowers are ver>' frequently pistillate. In 
both t>'pes 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 (salsif>'}. 
Pappus not plumose. 
Pappus of mere cba& or these reduced and united into a crown, 

Cichorium (chicor>). 
Pappus of capillary bristles. 
Achenes flattened, Laciuc^i (lettuce). 
Achenes not flattened. Taraxacum (danddion). 
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, Carduus (thistle). 
Anthers not tailed at the base; flowers tubular only, or tubular and ligulate. 
- Receptacle naked. 

Ray flowers yellow; involucral bracts scarcdy imbricated. Arnica. 
Ray flowers never yellow; involucral bracts wefl imbricated. 
Bracts of involucre imbricated in several saies. Aster. 
Bracts of involucre in but one or two series, Erigeron (fleabane). 
Receptacle chafly. 

Bracts of involucre foliaceous, Hdianthus Qenisalem artichoke and 

sunflower;. 
Bracts of involucre dr>% thin, and pajjery. 
Receptacle chatty, AckilU^ (\-arrow^>. 
Receptacle not cha5"y, naked, or sometimes hair>*. 
Ray flowers present. Chrysanthemum. 
Ray flowers none, Arittr.-.sia (sage and wormwood). 



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COMPOSITiE 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 var)dng 
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 Corbetl.) 

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 inflorescence 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 
naked. The corolla rays are truncate and five-toothed at 



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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 Corbett.) 

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 



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COMPOSITiE 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 Corhett.) 

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. saliva and L. scariola is shown by the fact that they readily 
cross. 



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632 BOTANY OF CROP PLANTS 

There are a number of native species of Lacttica 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 porrif olius) . From left to right: unopen 
flower head; side view and face view of open flower head; achene with pappus at 
tip of beak. 

Types 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. sativa var. angustana (asparagus 
lettuce). ^ 



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COMPOSITE 633 

Basal leaves broad, spatulate, oval to roundish, always rounded at the tip. 
Leaves deeply cut on the edges, L. saliva var. intybacea (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. capilala (head or cabbage lettuce). 
Leaves forming a conical or cylindrical-shaped head; leaves straight and 
stiff, L. saliva var. romana (cos lettuce). 



ohes 
tube 



Fig. 260. — Single flower of salsify (Tragopogon porrifolius). X 2^. 

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 PORMFOLroS (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 sea3on 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 



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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 porrif olius) . Headin fniit; 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). 



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COMPOSITE 63 s 

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 Cichorium are natives of the Old World. 
There are two of economic importance: Cichorium intyhus (chicory) and 
Cichorium endiva (endive). 



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636 BOTANY OF CROP PLANTS 

CICHORIUM mXYBUS (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. 

UseSy 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 achenes are angular and ribbed. 



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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 iH. 



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638 



BOTANY OF CROP PLANTS 



Geographical DistributioDy and Eccmomic 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. 



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COMPOSITE 6^g 

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 ciliate, squarrose bracts. There are 12 to 20 
rays. The receptacle is chaffy; the chaff subtends the disk 
flowers. The achenes 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 Topinambour) is native to this country 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. Agr. Bur. Plant 
Ind. Bull. 69: 1-103, 1905. 



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GLOSSARY 

AbaxUe. — Situated off the axis. 

Abortive. — Imperfectly formed or rudimentary. 

Acaulescent. — Without an obvious stem. 

AccumberU (cotyledons). — Their edges against the hypocotyl. 

Achene (akene). — A one-celled, dry, indehiscent fruit in which the testa 
and pericarp are not firmly attached. 

Acropeial. — Developing from the outside (below) toward the inside (above). 

Actinomorphic. — 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. 

Aestivation. — 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. 

Ament. — Scaly unisexual spike of flowers. 

Amphitropous (ovules). Half -in verted and straight, with the hilum about 
the middle, and micropyle terminal. 

Anatropous (ovnles). — Inverted, straight and with micropyle next the 
hilum. 

Androecium. — The 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 



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642 BOTANY OF CROP PLANTS 

Awned. — Furnished with an awn or beard. 
Axillary (buds, etc.). — In the axil. 

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. 

Bipinnate (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. 

Bracteclale. — Bearing bractlets. 

Bractecle. — A small bract. 

Bulbils. — Small bulbs borne underground, as in garlic. 

Bulblets. — Small bulbs borne above ground, as in tree onions. 

Cambium. — The growing layer in the vascular bundle. 

Campanulate. — Bell-shaped. 

Campylotropous (ovule or seed). — Curved so as to bring the apex and base 
near together. 

Capillary. — Hair-like in form. 

Capitate. — KLnob-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 dry, 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. 

CauUflcrus. — Stem-flowering; trunks bearing flowers, as in figs. 

Cauline. — Pertaim'ng 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. 



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GLOSSARY 643 

Conduplicate. — Folded lengthwise. 

Connivem, — Overlapping or brought close together. 

Convergent. — ^Margins touching. 

Convolute. — Rolled lengthwise. 

Cordate. — Heart-shaped. 

Corneus. — Horny. 

Corm. — The swollen, fleshy, and solid base of a stem. 

Cortex. — Bark region, from epidermis to endodermis. 

Corymb. — An indeterminate type of inflorescence that is flat-topped. 

Corymbose. — Corymb-like. 

Crenate. — Margins with rounded teeth. 

Crenidate. — With very small rounded teeth; diminutive of crenate. 

Cidm. — 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. — A 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. 

Dioecious. — 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 away from the main axis. 



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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. 

Elliptic, — Oval, or the shape of an ellipse. 

Emarginate. — Notched at the apex. 

Embryo, — Yooing 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 sepab. 

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. 

Erose. — With an irregular margin, as if chewed. 

Etiolate. — To whiten, or blanch, by the exclusion of light. 

Exocarp. — Outer wall of pericarp (ovary wall). 

Exserted (stamens). — Extending beyond the other flower parts. 

Exstipulate. — 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 . 

Geitonogamy. — A method of pollination in which pollen is taken from anther 
to stigma of another flower on same plant. 



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GLOSSARY 645 

Geniculate. — Bent abruptly 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. 
GyncBcium. — The carpels taken collectively. 

Hasiate. — ^Halberd-shaped; basal lobes diverging. 

Head. — An indeterminate type of inflorescence in which the flowers are in 
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. 

^/r^w^e.— 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. 

Indehiscent. — Not splitting open. 

Indigenous. — Native to the region of growth. 

Inferior (ovary). — Below the other flower parts. 

In flexed. — Bent inwards. 

Inflorescence. — A flower cluster. 

Integument. — Skin; coat or protecting layer. 

Internode. — 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. 

Involucd. — A secondary involucre. 

Invclucellate. — Furnished with involucels. 

Involucrate. — 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. 



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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. 

Leniicidar. — Shaped like a double-convex lens. 

Lignified. — Woody; cell walls impregnated with lignin. 

Ligidate. — Strap-shaped. 

Ligide. — 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. 

Locide. — 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. 
MeduUa.—Fith. 

Mericarp. — One-half of the fruit of Umbellif erae. 
Mesocarp. — Middle layer of pericarp (ovary wall). 
Mesocotyl. — Axis between base of coleoptile and grain, in grasses. 
Micro pyle. — The opening between the ovule or seed coats. 
Micros porangium. — Anther sac; case bearing microspores. 
MoncBclous. — 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. 
Nucellus (megasporangium). — The ovule tissue within the integuments. 
Nutlet. — A small nut. 

Oh. — A prefix signifying inversion. 

Ohcordate. — Heart-shaped, with broad end at the tip. 



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GLOSSARY 647 

Oblate. — Flattened at the ends. 

Ohovate. — Egg-shaped in outline, with the broader end at the tip. 
Obsolete. — Rudimentary, or entirely absent. 
Obtuse. — Blunt, or rounded at the apex. 
Ocrea. — Sheathing stipules in Pol)rgonaceae. 
Orbicidar. — ^Approximately circular in outline. 

Orthotropous (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 body which becomes the seed after fertilization. 

Palei (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-like, awn-like scaly structures (modified calyx) at the tip 
of the ovary in Compositae. 

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 year. 

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. 

Perigynous. — Calyx, corolla, and stamens borne on a rim of the receptacle 
such that they appear on the level with the ovary. 

Perisperm. — Nucellus. 

Pe/a/oiJ.— Petal-like. 

Petiole.— The stalk of a leaf. 



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648 BOTANY OF CROP PLANTS 

Phloem. — That portion of a vascular bundle which is largely concerned in 
the transport of elaborated food material. 

Phyllotaxy. — The arrangement of leaves upon a stem. 

Pileole. — Coleoptile (which see). 

Pinnate (leaf). — ^Leaflets arranged along the sides of an axis. 

Pinnatifid. — Pinnately cleft to the middle of the blade, or further. 

Pistillate. — Bearing pistils only. 

Placenta. — The membrane or surface bearing ovules. 

P//c(i/e.— Plaited. 

Plumcse. — Plume- or feather-like. 

Plumule. — The first bud in the young plant. 

Polyadelphous (stamens). — Separate, or in more than two groups. 

Pclygamo-dicecious. — 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. 

Raceme. — 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 (cauUne). 

Ray. — The branch of an umbel; marginal, ligulate flowers of a composite 
head. 

Rece ptacle. — The end of the axis to which the floral organs are attached ; 
torus. 

Reflexed. — Turned back. 

Regular (flower). — The parts of each whorl similar. 

Reniform. — Kidney-shaped. 

Reticulate. — Netted. 

Retrorse, — Turned back or downward. 



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GLOSSARY 649 

Rhizome. — Rootstock; underground stem, usually horizontally elongated. 
Rotate. — Wheel-shaped. 
Ruder al. — 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. 

Sclerenchymatous. — Composed of cells that fit closely together and have 
thick, hardened walls. 

Scutellum. — 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. 

Silique. — 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. 

S pikelet. — 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. 

Staminate (flowers). — Bearing stamens only. 

Staminodeal. — Pertaining to staminodia, i.e., abortive and sterile stamens. 



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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; ako 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. 

Syngenesiou?. — With the anthers united, as in Composite. 

Tassel. — Staminate inflorescence in corn. 

Tendril. — Slender, coiled organ used in climbing. 

Terete. — Cylindrical; i>encil-shaped. 

Ternate. — Arranged in threes or divided into three divisions. 

Testa. — Seed coat. 

Tillering. — Production of branches from the lowermost nodes, as in grasses. 

Tomentose. — Covered with dense wool-like hair. 

Tomentum. — 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. 

Tubercidate. — Furnished with tubercles or small projections. 

Tuberous. — Swollen and tuber-like. 

Tubular. — Tube-shaped. 

Turbinate. — Top-shai>ed, 



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GLOSSARY 651 

Umbel. — An indeterminate type of inflorescence, in which the pedicels 
arise from the same point. 
Umbellate, — Umbel-like. 
UmbeUet. — Umbel of secondary order. 
Undulate. — With wavy margin. 
Utricle. — A one-seeded fruit with a bladder-like covering. 

Valvate (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. — Arrangement of leaves in the bud. 

Versatile (anther). — Filament is attached near middle of anther, so that 
it can readily turn in any direction. 

Fexi//ttw.— Standard of the flower in Leguminosae. 

Viscid. — Sticky. 

Vitta (pi. vittae). — Oil tubes in Umbellifer fruit. 

Wing. — ^Lateral petal in the flower of Leguminosae. 

Whorl, — A group of organs arranged in a circle about a stem, and arising 
from the same node. 

Zygomorphy (flower). — See Irregular. 



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Digiti 



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INDEX 



Abutilon, 506 
Abyssinian oats, 130 
Achene, 58 
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 
Algae, 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, 238 



Almond, 410 

bitter, 411 

hard-shelled, 411 

oil, 411 

soft-shelled, 411 

sweet, 411 
Aloe, 229 
Alo|>ecurus, 79 
Alsike clover, 433, 434 
Althaea, 506 

officinalis, 507 

rosea, 507 
Amarelles, 404 
Amaryllidaceae, 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 
Angiospermae, 62 
Animated oats, 131 
Annual ring, 40 
Annuals, 21, 70 
Antennaria, 625 



653 



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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, hypogoea, 462 
Aragallus, 414 

Arctostaphylos uva-nrsi, 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 

medeoloides, 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, 151 

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 
Bambusae, 84 
Banner, 414 

oats, 130 
Banyan, 16 

tree, 267 
Barbe de Capuchin, 636 
Bark, 39, 40 
Barley, 72, SS, 89, 135 

black, 145 



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INDEX 



655 



Barley, blue, 145 

fan, 146 

four-rowed, 144 

hooded, 136, 137, 145, 146 

huU-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, 219, 220 
Basidiomycetes, 64 
Basin, 378 
Bean, 421 

adjuki, 423 

asparagus, 42^, 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 cerifera, 613 
Betgamot, 487 
Beriberi, 206 
Berry, 59 
Berseem, 433 
Beta, 298 

cycla, 3J2 

maritima, 301 

vulgaris, 300 
Bidens, 625 
Biennials, 21 
Bigarreaus, 403 
Bilberry, dwarf, 54O 

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 

blueberry, 547 
■ -cap raspberry, 357 

mulberry, 255, 257 

mustard, 327, 339 

nightshade, 560 

salsify, 635 
Blackberry, 354 



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6s6 



INDEX 



Blackberry, dewberry, 354 

high-bush, 354 

key to principal species of, 354 

leafy-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, 333 



Brassica, oleracea, gemmifera, 329, 330 
viridis, 329, 330 

rapa, 65, 328, 335 
Bread-fruit, 252 
Breaking, hemp, 280 
Brebas, 275 
Brewing process, 149 
Britbh 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 

BrussePs 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 



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INDEX 



657 



Buds, terminal, 24 

supernumerary, 24 

whorled, 25 
Buffalo bur, 561 

currant, 319 
Bulbs, 32, 229 
BuUaces, 400 
Bulletin Smyrnas, 275 
Bundle scar, 26 
Bupleurum, 530 

Cabbage, 328 

common, 331 

key to cultivated types of, 329 
types of common head, 332 

lettuce, 633 
Calamondin orange, 487 
Calendula, 625 
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 
Capparidaceae, 326 
Caprification, 273 
Caprifig, 269, 272, 276 
Capsaican, 595 
Capsella, 326 
Capsicum, 560, 595 

annuum, 592 
42 



Capsicum, annuum, abbreviatum, 595 

acuminatum, 595 

cerasiforme, 595 

conoides, 595 

fasciculatum, 595 

frutescens, 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 
Cauliflower, 330, 334 
Cavity, 378 
Cayenne pepper, 595 
Celeriac, 540 
Celery, 540 
Cell, 4 

as unit of structure, 5 

of plant activity, 5 
Cell sap, 6 

wall, 6, 8 
Celluloid, 526 
Central cylinder, 1 7 
Cercocarpus, 348 
Cereals, 87 

key to groups (genera) of, 87 

small-grain seedlings of, 88 
Chaetochloa, 88, 210, 211 
italica, 211, 216, 218 

key to principal types of, 218 

maximum, 218 

moharium, 219 



Digiti 



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6s8 



INDEX 



Chaetochloa, viridis, 211, 219 
Chard, 312 
Charlock, 339 
Chasmogamy, 82 
Chenopodiaceae, 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 came, 596 
Chinese cotton, 517 

mustard, 340 

pear, 384, 385 
Chiogenes hispidula, 543 
Chives, 237, 238 
Chlorophyceae, 63 
Chloroplastids, 8 
Chromoplastids, 8 
Chrysanthemum, 625, 628 
Chr3rsothamnus, 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 
CitruUus, 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, 485 

sinensis, 480, 484 
Cive, 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, 439, 441 

meadow, 441 

medium red, 441 

Persian, 433 

purple, 436 

red, 433, 43^ 

scarlet, 433, 435 

Shaftal, 433 

spotted bur, 442, 449 

Swedish, 433, 43*4 

sweet, 452 

toothed bur, 442, 452 

white, 433, 44i 

zigzag, 433, 441 
Cloudberry, 350 
Club mosses, 62 

wheat. III, 112, 114 
Cob, 163 
CofiFee bean, 456 
Coleanthus, 81 



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INDEX 



6S9 



Coleoptile, 104 
Coleorhiza, 10, 103 
Collard, 329, 330 
Collodion, 526 
Colocynth, 622 
Columnar epithelium, 104 
Commissure, 532 
Conunon apple, 379, 381 

apricot, 405 

barnyard grass, 210 

bread wheat, iii, 112, 113, 114 

buckwheat, 289 

eggplant, 586 

fig, 269, 275 

gray buckwheat, 294 

liop, 33 

millet, 219 

onion, 232, 237 

pear, 384, 385 

six-rowed barley, 144 

sugar beet, 300, 310 

sweet pea, 432 

wheat, 65, n I, 112, 114 
Companion cells, 35 
Compass plant, 632 
Composite family, 625 
Compositae, 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 



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66o 



INDEX 



Crab-apple, western, 379, 381 
Cranberry, 548 

American, 548 

European, 544 

large, 548 

mountain, 550 

small, 548, 549 

types of, 549 
Crataegus, 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 

Cucurbitaceae, 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 



Digiti 



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INDEX 



66l 



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 
Dracaena, 229 
Dried apples, 383 
Drosera, 47 

Drumhead cabbages, 332 
Drupe, 393 
Drupaceae, 391 
Duboisia hopwoodii, 600 
Duckweed, 2 
Dukes, 403 
Durra, 196, 1^7 

Durum wheat, 89, iii, 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 elaterium, 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, so 
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 



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662 



INDEX 



Erinocyce figs, 275 
Eriogonum, 285, 286 
Eryngium, 530 
Euchlaena 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 

Smjrrna, 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, 48 
Fly oats, 131 
Foeniculum, 533 



Digiti 



zed by Google 



INDEX 



663 



Foliage beet, 310 
Follicle, 58 
Forage crops, 186 
Foreign onions, 243 
Fortunella, 476, 487 

crassifolia, 489 

hindsii, 489 

japonica, 489 

margarita, 488 
Four-rowed barley, 144 
Foxberry, 550 
Foxtail millets, 211, 216, 219 

grass, 211 
Fragaria, 358 

califomica, 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, 547 

key to North American species of, 

547 
resinosa, 547 



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, 15s 

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 



Digiti 



zed by Google 



664 



INDEX 



Gourd, winter, 615 
Grafting, 36 
(Jraham flour, 108 
Grain, 83 

coats, 96 
CJramineae, 69 
Granules, 8 
Grape, 492 

Catawba, 501 

Concord, 501 

Delaware, 501 

family, 491 

Muscat, 4q8 

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 



Grossulariaceae, 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, hem{), 280 
Hairs, basal, 92 
Hairy vetch, 427, 430 
Halophyte, 296 
Head, 56 

lettuce, 633 
Hearts, 403 
Heath family, 543 
Hedysarae, 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, 33, 252 



Digiti 



zed by Google 



INDEX 



665 



Hop, clover, 442, 449 
-meal, 264 
-tree, 475 
Hordeum, 88, 135 

distichon, 135, 136, 137, 143, MS 
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 
neomexicanus, 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 
Imperatrice 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 
Internodes, 72 

Intracalicary organs, of cotton, 513 
Involucre, of cotton, 512 
Ipomoea, 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 



Digiti 



zed by Google 



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, 485 
Kinkan, 487 
Kinnikinic, 543 

Kleinwanzlebener sugar beet, 308 
Knaurs, 553 
Knotberry, 350 
Knot weed, 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 
Lathy rus, 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 
Leguminosae, 413 

key to principal genera of, 416 
Lemma, 80 
Lemon, 481 

Ichang, 487 
Lenticel, 27 
Lepidium, 326 
Lespedeza striata, 465 
Lettuce, 628 



Digiti 



zed by Google 



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, 33 
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, 27s 
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 
Ivow 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, 179 
Maize, 88, 157 
Male nuclei, 50 
Mallow family, 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 
Malvacese, 505 

key to important genera of, 508 
Mamme, 272 
Mammoni, 272 



Digiti 



zed by Google 



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 
confinis, 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, i43» i4S» 146 

red clover, 441 
Medulla, 18 
Medullary ray, 35, 39 
Megarhiza calif omica, 610 
Melilot, 453 
Melilotus, 452 



Melilotus, alba, 453, 454 

altissima, 454 

graciUs, 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 
MendePs law, 421 
Mericarp, 532 
Meristem tissue, 33 
Mescmbryaceae, 299 
Mesocarp, 58 
Mexican bean, 424 

grass, 182 
Micrampelis, 608 
Micropyle, 50, 57 
Middlings, 108 
Millet, 88, 210 

African, 213 

Aino, 218 

barnyard, 210, 219 

broom-corn, 210, 213 

Egyptian, 213 

foxtail, 211, 216 

German, 218 

Golden Wonder, 218 

Hog, 213 

Horse, 213 

Hungarian, 219 

Indian, 213 



Digiti 



zed by Google 



INDEX 



669 



Millet, Japan, 21 3 

Japanese barnyard, 210, 220 

key to principal economic types 
(species) of, 210 

pearl, 211 

proso, 210, 213 

Siberian, 218 

true, 210 
Milo, 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, 33 

famUy, 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,