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THE
BOTANY OF CROP PLANTS

ROBBINS

THE

BOTANY OF CROP PLANTS

A TEXT
AND REFERENCE BOOK

WILFRED W. ROBBINS, Ph. D.

PROFESSOR OF BOTANY, COLORADO AGRICULTURAL .'tJLLEGE

WITH A GLOSSARY AND
263 ILLUSTRATIONS

PHILADELPHIA
P. BLAKISTON'S SON & CO,

1012 WALNUT STREET

THE MAPLE PRESS VORK PA

PREFACE

This book has grown out of a course of instruction ex-
tending over a number of successive years. Most of the
material presented here, except Part I, has been used in
mimeographed form in college freshmen classes, not only as
a text from which to make assignments, but also as a guide
and reference in the laboratory. The issuance of the book
has been stimulated in part by the expressed need of a number
of schools for a text and reference book which will give the
student a knowledge of the botany of common orchard,
garden and field crops, and it is the author's wish that the
material brought together from many sources and organized
in the present form will meet this need, at least in a measure.

It has seemed advisable to include chapters (Part I) which
may be needed in some instances to refresh the student's
knowledge of certain fundamentals, or prepare him for that
which follows in Part II. But in many schools Part II will
be preceded by a general course which aims to give the stu-
dent a survey of the plant kingdom and an acquaintance with
the large outstanding facts and principles of botany, and in
this case Part I will be omitted. The subject matter of
Part II is sufiicient 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.

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 taken verbatim. A
majority of the illustrations are original. It is believed that
the direct method adopted herein of labeling drawings will
appeal to both students and teachers.

Almost all original illustrations, and also those copied or
adapted are the work of Mr. N. Lee Foster. The writer is
especially indebted to him, not only for the delineation, but
for his helpful interest and valued cooperation throughout.
Professor D. W. Frear, formeily Associate Professor of
Agronomy at the Colorado Agricultural College, now of the
North Dakota Experiment Station, is to be given credit for
organizing and writing up portions of Chapters IX, XVII,
XXX and XXXVIII. The text was planned and outlined
by Professor Frear and the undersigned as joint authors,
but unavoidable exigencies 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 Agricui-tural College

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 Structxjre 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 E.xternal Factors upon Develop-
ment of Root Hairs — ^Length of Life of Roots 10-21

CHAPTER IV.— Stems.

Development of Shoot System — Buds— Classification of
Buds — Bud Variation — General Characteristics of Stems —
How Does a Stem Grow in Length — Classification of Stems
Based upon Their Medium of Growth — "Modified" Stems —
Structure of Stems — The Young Dicot Stem — Dicot Vas-
cular Bundle— Growth in Thickness of Dicot Stem— Monocot
Stems— Annual Rings — Bark — The Work of Stems 22-41

CHAPTER v.— 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 PoUen ' Grain — Pistil — Ovule — Pollina-
tion— Fertilization — Placentation — Symmetry of Flower —
Relative Positions of Flower Parts — Union of Flower Parts —
Incomplete Flowers — Inflorescence 48-56

CHAPTER VII.— Fruits, Seed, and Seedlings.

Development of the Seed — Development of the Fruit — Fruit
and Seed Distinguished — Kinds of Fruits — Germination of

the Seed 57-59

vii

VIU CONTENTS

CHAPTER VIII. — The Classification and Naming of Plants.
Reproductive versus Vegetative Organs in Classification —
Groups of Plants — The Plant Kingdom — Plant Nomenclature
— Scientific Name — Scientific Name versus Common Name —
General References 60-67

PART II

CHAPTER IX.— GRAMiNEiE (P0ACE.E) 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 91-1 21

CHAPTER XI.— AvENA (Oats).

Habit of Plant— Roots— Stems — ^Leaf— Inflorescence— Spike-
let and Flower — Opening of Flower and Pollination — Fertiliza-
tion and Maturing of Grain — The Mature Grain — Germina-
tion of Oats — Classification of Oats— Other Cultivated Oats
— A vena fatua ("wild oats") — Origin of Oats — Environmental
Relations — Uses of Oats — The Production of Oats —
References .' 122-134

CHAPTER XII.— HoRDEUM (Barley).

Habit of Plant, Roots, Stems, Leaves — Spikelet and Flower —
Opening of Flower and Pollination — Fertilization and Matur-
ing of Grain — Mature Grain of Barley — Color of Grain-
Germination of Barley — Classification of Barleys — Origin
of Cultivated Barleys — Environmental Relations— Uses of
Barley — The Brewing Process — Production of Barley-
References 135-152

CONTENTS IX

CHAPTER XTII.— Secale cereale (Rye).

Habit of Plant, Roots — Steins, 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 iS3-i56

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

CHAPTER XV. — Andropogon Sorghum (Sorghums).

Habit of Plant, and Roots — Stems and Leaves — Inflorescence
— Spikelets and Flowers — Fertile Spikelet — Staminate Spike-
let— Opening of Flowers and Pollination — Fruit — Varieties —
Key to Principal Groups of Sorghum — Origin of Sorghums —
Environmental Relations — Uses of Sorghums — References. .191-201

CHAPTER 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 210-211

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

Varieties — Origin 211-213

Panicum miliaceum (Proso, Hog or Broom-corn Millet) —
Stem — ^Leaf — Inflorescence — Spikelet and Flower — Pollina-
tion— Mature Grain — Varieties — Origin 213-216

Chaetochloa italica (Foxtail Millets) — Steam — ^Leaf —Inflores-
cence— Spikelets and Flower — Pollination — Mature Grain-
Types and Varieties of Foxtail Millet — Key to Principal Types of
Foxtail Millets (Chaetochloa italica) — Origin of Foxtail Millet. 216-219

X CONTENTS

Echinochloa Crus— galH (Barnyard Grass or Barnyard
Millet) — Habit, Stems, Leaves — Inflorescence, Spikelet,

Flowers, and Fruit — Distribution 219-220

Echinochloa frumentacea (Japanese Barnyard Millet) 219-220

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

CHAPTER XVIII.— Phleum pratense (Timothy).

Description — Environmental Relations — Closely Related Spe-
cies— References 222-224

CHAPTER XIX.— Saccharum officinarum (Sugar Cane).

Habit, Roots — Stems — ^Leaves — Inflorescence, Flowers, Fruit
— Geographical — Sugar from Sugar Cane — Production of Cane
Sugar 225-228

CHAPTER XX.— Liliace^ (Lily Family).

Habit, Roots — ^Leaves — Inflorescence and Flowers — Fruit and

Seeds 229-230

Allium — Roots — Stems — Leaf — Inflorescence — Flower — Polli-
nation— Fruit — Germination of Seed, and the Seedling —
Geographical— Key to the Principal Cultivated Species of

Genus Allium 231-237

Allium sativum (Garlic) 237

Allium porrum (Leek) 238

Allium schcenoprasum (Chives or Gives) 238

Allium ascalonicum (Shallot) 238-239

Allium fistulosum (Welsh Onion or Ciboule) 239-240

Allium cepa (Onion) — Description — History — Types of Onions
— Foreign and Domestic Onions — Composition of Onions —

Uses of Onions 240-244

Asparagus — Generic Description — Economic Importance of

Genus 244-246

Asparagus ofl&cinalis (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

Moms (Mulberry)— Habit, Stems — Leaves — Inflorescences —
Fruit— Other "Mulberries"— Geographical— Key to Principal

Species of Genus Morus 253-255

Morus alba (White Mulberry) — Description — Geographical
— Types and Varieties — Economic Importance — Early At-
tempts in the United States to Grow Silk— Uses 255-257

Morus nigra (Black Mulberry) — Description^ — Geographical

—Varieties— Uses 257-258

Morus rubra (Red Mulberry)— Description — Geographical-
Varieties and Uses 258

CONTENTS XI

Humulus (Hop). Humulus lupulus (Common Hop) — Root —
Stems — Leaves — Inflorescences — Flowers — 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— Types of Figs — Uses of Figs 269-276

Cannabis sativa (Hemp) — Description — Geographical — Varie-
ties— The Hemp Industry in the United States — Preparation
of Hemp for Market — Uses of Hemp — Sisal Hemp —
References 276-283

CHAPTER 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 XXIII. — 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 313-315

XU CONTENTS

CHAPTER XXIV.— Geossulariace^ (Gooseberry Family).

Stems — Leaves — Inflorescence and Flowers — Pollination —
The Mature Fruit — Seeds — Geographical — Key to Important

Species of Genus Ribes 316-319

Currants — Species — Uses 320-321

Gooseberries — Species — Uses 321-322

CHAPTER XXV.— Crucifer^ (Mustard Family).

Stems, Leaves — Inflorescence and Flowers — Fruit — Seeds —

Closely Related Families — Key to Principal Genera 323-326

Brassica —Generic Description — Pollination — Seedling — Geo-
graphical— Key to Principal Species of Genus Brassica 327-328

Brassica oleracea (Cabbages, etc.) — Wild Cabbage — Cultivat-
ed Types of Cabbages— Key to Cultivated Types of Cabbage. 328-330

Brassica oleracea var. viridis 330

Brassica oleracea var. gemmifera (Brussels Sprouts) — Types

— Uses 330-33^

Brassica oleracea var. capitata (Common Head Cabbage) —

Types — Key to Types of Head Cabbage — Uses 331-33.3

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 Riadish) — Habit— Root— Stem-
Leaves — Inflorescence and Flowers — Fruit — Seeds and Seed-
ling—Geographical Distribution and Origin — Closely Related

Species — T3^es 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.— Rosacea (Rose Family).

Leaves — Inflorescence — Flowers — Fruit — Key to Important

Genera of Rosaceae 348-35°

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

CONTENTS Xlll

Fruit — Geographical — Classification — Key to Groups of Genus

Rubus 350-354

Blackberries — Key to Species of Blackberries — Rubus nigro-
baccus — Rubus nigrobaccus X R. villosus — Rubus argutus —

Rubus cuneifolius 354-355

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
occidentalis — Rubus idaeus — Rubus strigosus — Rubus stri-

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

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

CHAPTER XXVIL— Pomaces (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 Development — Key to Principal
Species of Malus — 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^ (Plum Family).

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

Prunus — Key to Main Groups of Genus Prunus 394

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

Species of Plums 394-397

Discussion of Species — Prunus domestica — Prunus insititia—

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 — UscSt— Almond

Oil— References .410-412

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 41 7-421

Phaseolus (Bean) —Description — Geographical, and Species —

Key to Principal Species of Phaseolus 421-424

Phaseolus lunatus (Sieva and Lima Beans) — Classification of
Types of Lima Beans— Table Showing Relationship of Types of

Lima Beans 424-426

Phaseolus vulgaris (Kidney Bean) — Uses of Beans 426

Vicia (Vetch, Broad Bean) — Generic Description — Geographi-
cal— Key to Important Species of Vicia — Less Common

Species 426-429

Vicia faba (Broad Bean, Windsor Bean) 429

Vicia sativa (Common Vetch or Tares)— Uses 429-430

Vicia villosa (Hairy, Russian, Siberian, or Villous Vetch) 430-432

Lathyrus (Vetchling, Wild Pea) ■ 432

Trifolium (Clover) — Generic Description — Geographical-
Key to Principal Species of Trifolium 432-433

Trifolium repens (White or Dutch Clover) — Description —

. Geographical, and Uses — Environmental Relations 433-434

Trifolium hybridum (Alsike, Alsatian, or Swedish Clover) —

Description — Geographical, and Uses. 434-435

Trifolium incarnatum (Crimson, Scarlet, or Italian Clover) —
Description — Geographical, and Uses — Environmental Rela-
tions 435-436

Trifolium pratense (Common Red or Purple Clover) —
Habit, Stems, Roots — ^Leaves — Inflorescence and Flowers —

CONTENTS XV

Fruit— Pollination — Geographical — Environmental Relations

—Mammoth Clover — Uses 436-440

Trifolium medium (Zigzag, Medium Red, "White, Mammoth

or Meadow Clover) 44i

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

Melilotus 452-454

Melilotus alba (White Sweet Clover) — Description 454

Melilotus ofhcinalis (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..458-46o
Vigna sinensis (Cowpea) — Description — Environmental Rela-
tions— Uses 460-462

Arachis hypogoea (Peanut, Goober) — Habit, Stem — ^Leaves —
Flowers — Development of Fruit — Fruit — Types — Environ-
mental Relations 462-465

Less Important Legumes 465-467

References 467-468

CHAPTER XXX.— Linages (Flax Family)

Habit, Stem, Leaf — Inflorescence and Flowers^Fruit — The
Names Derived from"Linum" — Geographical, and Environ-
mental Relations 469-470

Linum usitatissimum (Common 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

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 Grange.489
References 489-490

CHAPTER XXXII.— ViTACE^ (Grape Family).

Family Description — Geographical — Key to Important

Genera 491-492

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

Habit — Leaves — Flowers^-Fruit and Seeds — Geographical —
Economic Importance — Key to Important Genera of Mal-
vaceae 5oS~So8

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— Types — Uses 527-528

References 528-529

CONTENTS XVll

CHAPTER XXXIV.— UMBELLiFEEiE (Carrot Family).

Stems and Leaves — Inflorescence and Flowers — Fruit —

Geographical — Key to Genera of Economic Importance S3o~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 S36-538

Apium (Celery and Parsley) — Generic Description — Geo-
graphical— Key to Principal Species of Apium 53^-539

Apium petroselinum (Parsley) — Description — Varieties 539-54°

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

References 542

CHAPTER XXXV.— Vacciniace^ (Huckleberry Family).

Habit — ^Leaves — Inflorescence and Flowers — Fruit 543-545

Vaccinium — Pollination — Fruit — Geographical — Key to Chief

Fruit-bearing Species of Vaccinium 545-547

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

of Gaylussacia 547

Cranberries — Vaccinium macrocarpon — Types — Vaccinium

oxycoccus, Vaccinium vitis-idaea 548-550

Huckleberries and Blueberries 550

References 550

CHAPTER XXXVL— Oleace^ (Olive Family).

Family Description — Geographical, and Economic Impor-
tance 551

Olea europoea (Olive) — Description — Seed Germination —
Propagation — Uses 551-553

CHAPTER XXXVII.— CoNVOLVULACE^ (Morning Glory Family).
Habit — ^Leaves — Inflorescence and Flowers — Fruit — Key to

Important Genera 554-555

Ipomoea batatas (Sweet Potato) — Roots and Stems — ^Leaves—
Inflorescence and Flowers — Geographical, and Environmental
Relations — Closely Related Species — Types and Varieties —
Leaf Shape as a Basis of Classification — Uses — References. .555-558

CHAPTER XXXVIII.— SoLANACEiE (Potato Family).

Habit of Plants — Leaves — Inflorescence and Flowers — Fruit

— Key to Important Genera 559-560

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

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

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 — Types and
Varieties— Composition — Curing Tobacco — The Tobacco In-
dustry—References 597-605

CHAPTER XXXIX.— CucuEBiTACE^ (Gotod 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 — T3T)es and Varieties 614

Cucurbita moschata — Description — Types 615

Cucumis (Muskmelon, Cantaloupe, Cucumber) —Stems,
Leaves, Flowers — Pollination — Geographical — Key to Prin-
cipal Species 615-617

CONTENTS XIX

Cucumis melo (Muskmelon, Cantaloupe, Melons) — Descrip-
tion— Botanical Varieties of Cucumis melo 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.— Composite (Thistle Family).

Habit — Leaves — Inflorescence — Flowers — Key to Important

Genera 625-628

Lactuca sativa (Garden Lettuce) — Description — Origin, and
Geographical — Types of Lettuce — Key to Types of Lettuce. . 629-633
Tragopogon porrifolius (Salsify or "Oyster Plant") — Descrip-
tion— Geographical, and Closely Related Species — Uses 633-635

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

Geographical 635

Cichorium intybus (Chicory or Succory)— 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 .

BOTANY OF CROP PLANTS

PART I

CHAPTER I
THE SEED PLANT BODY

The seed plant body, like the human body, is made up of
a number of separate parts or members. In the lowest plant
group, the Thallophytes (thallus plants), including algae
(pond scums, sea weeds, etc.), and fungi (molds, mildews,
mushrooms, etc.), the plant body is relatively simple; it is
not composed of distinct members, such as leaves, stems,
roots and flowers. Such a simple, undifferentiated plant
body is called a thallus. Between the typical thallus of algae
and fungi on the one hand, and the highly complex and well-
differentiated body of seed plants on the other, there are
many intermediate forms, as for example, among the liver-
worts (Hepaticae).

Principal Parts of Seed Plant Body. — The parts of the
plant body may be classified according to the work they do,
into two groups: (i) those that carry on vegetative activity;
and (2) those that carry on reproductive activity. In seed
plants, the stems, leaves and roots are chiefly concerned with
maintaining the life of the individual plant, that is, carrying
on the vegetative (nutritive) functions, such as absorption of
materials from the soil, manufacture of foods, respiration,

2 BOTANY OF CROP PLANTS

transpiration, etc., while the flowers which produce seeds,
carry on, for the most part, the reproductive activities, and
thus preserve the 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 structural basis, as follows:

1. Shoot system, including stems, leaves, flowers, fruit and
seed. The stems may be in the air {aerial) or underground;
the leaves may be ordinary foliage leaves, floral leaves (flower
parts), or scale leaves.

2. Root system, which may be in the soil, the water or air.
The roots, stems, leaves and flowers are not always typical,

but may be modified or disguised, in some cases to such an
extent as to be scarcely recognizable. For example, the
tendril of the sweet pea is a leaf part, morphologically; the
potato tuber, a modified stem; the sweet potato, a modified
root.

Size and Form of the Seed Plant Body. — There is a re-
markable variety of forms and sizes of seed plants in the
world. The duckweeds are very small, simple seed plants
floating upon the surface of ponds. They are without leaves
or with only very simple ones, they bear one or more rootlets,
and extremely small flowers which usually consist of a single
stamen or a single pistil. At the other extreme are the Giant
Sequoias of California; one individual, the General Sherman
''big tree," measures 279.9 feet in height and 102.8 feet about
the base.

We commonly make a distinction between trees, shrubs and
herbs — plants which differ much in form and habit. Trees
and shrubs are woody, while herbs possess iess woody tissue

THE SEED PLANT BODY 3

and, consequently, are more soft and tender. The tree has
a main trunk giving off branches at varying distances from
the ground. The shrub may have a small main stem, but
the shoots that arise at its base are equal to it in size. We
note differences in the shapes of plants. Contrast the apple
tree with its oval shape with the cone shape of the pine or
spruce. Observe the general columnar form of the corn
plant, and note how different it is from the broadly oval form
of a vigorous alfalfa clump. Again, we see that while most
plants are erect, a number, like the strawberry and melons,
are prostrate on the ground. Others, like the grape, are
climbing, and gain mechanical support from other objects.

CHAPTER II

FUNDAMENTAL INTERNAL STRUCTURE OF PLANT
BODY

Organs and Tissues. — We have said that the seed plant
body is composed of a number of members: roots, stems,
leaves, and flowers, bearing the fruit and seed. We may say
that the plant body is composed of a number of organs, that
is, well-defined parts that perform some definite function or
functions. For example, those parts of the plant concerned
with absorption we call absorptive organs, those that carry on
reproduction, reproductive organs, and so on. The roots are
the chief absorptive organs of all common seed plants, and
the stamens and pistils of the flower the reproductive organs.
Now, if we study microscopically the structure of organs,
they are seen to be made up of one or more different groups of
cells. Each distinct group of cells within the organ that has
a common origin and a common role to perform, is desig-
nated a tissue. For example, the pistil (a reproductive organ
of a flower) is composed of several different tissues such as
parenchyma tissue, conductive tissue, and epidermal tissue.
Still deeper analysis of tissues shows all to be made up of
small microscopic units — the cells.

The Plant Cell. — Discovery of the Cell. — The discovery of
the plant cell is attributed to Robert Hooke, an Enghsh lens
manufacturer. In his microscopic study of thin sections of
ordinary bottle cork, in 1667, he observed the cork tissue to
be composed of very small compartments, very much alike
in size and shape, and fitting closely together. It happens

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.

The Cell as a Unit of Structure. — Just as a brick house is
made up of individual units, the bricks, so is a plant composed
of individual units, the cells. A plant is made up of cells and
the products of cells, and nothing else. The wood, the root,
the flower parts, the leaf, are made up of cells and cell prod-
ucts. This must not be understood to mean that all parts
of a plant are alive; but the non-Hving 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

6 BOTANY OF CROP PLANTS

the higher seed plants, there are many different sorts of cells,
both in structure and function, and the different cells are
more dependent one upon another than are the cells that
make up the simple algal filament. Yet, even in the seed
plant, each cell is a unit of activity, and each is carrying on
its functions more or less independently of its neighbors.
The physiological unit of the plant is the cell.

The Structure of the Plant Cell (Fig. i).— It must be
understood at the beginning that plant cells vary a good deal
in size and shape. However, the fundamental structure of
all plant cells is much the same. The plant cell consists of
a living mass {protoplast) of protoplasm enclosed in a non-
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, whichis only made manifest by treating
the cell in a special manner. This membrane is known as the
protoplasmic membrane, ectoplasm or hyaloplasm. It is all-
important in the intake and outgo of substances. If a plant
tissue is immersed in a sugar or salt solution which has a
greater concentration than the cell sap, water is drawn from
the protoplast of each cell through the protoplasmic mem-
brane, and the protoplast shrinks, thus pulling the membrane
away from the cell wall and making it visible microscopic-
ally. Imbedded within the body of the protoplast there is
a darker and denser mass of protoplasm, the nucleus, sur-
rounded by its own living nuclear membrane. It may con-
tain one to several small, darker bodies, the nucleoli. The
protoplasm outside the nucleus is designated the cytoplasm.
Hence we see that the protoplast is made up of three main
parts: protoplasmic membrane, cytoplasm and nucleus. The
protoplasm has spaces within it, which are filled with cell sap.

FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 7

These spaces are called vacuoles. However, one must not
think of the cell-sap spaces in the protoplasm as vacuums, as
the rather inappropriate name "vacuole" may suggest.
Vacuoles are numerous and small in the young cells, but as

Fig. I. — A, young cells from onion root tip; d., protoplasmic membrane; c,
cytoplasm; a, nuclear membrane; d, nucleolus; e, plastids (black dots). B,
older cells farther back from the root tip; /, vacuole; note that the cells have
enlarged. C, epidermal cell of Tradescantia zebrina; in its natural condition
of the right, and, on the left with the protoplast drawn from the cell wall as
the result of immersing the cell in a solution the concentration of which is
greater than that of the cell sap. . This phenomenon is called plasmolysis. g,
contains the plasmolyzing 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.

Plant cell

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 plasHds, 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. \ I plastids (living)

I „ ^ , j granules (living or non-living)

Cytoplasm, i ^ , , / ,. • n
[ I crystals (non-livmg)

[ vacuoles, containing cell sap.

The Cell Wall.— The cell wall is a product of the proto-
plast. When young it is almost pure cellulose. As the
cell grows older, its wall may thicken and become denser,
and have added to it certain substances such as lignin, su-
berin, cutin and pectin which give it different physical
and chemical qualities.

Plastids. — These are specialized masses of protoplasm
suspended within the cytoplasm. They vary in size and
form. There are three sorts of plastids based upon their
color: (i) leucoplastids, colorless; (2) chloroplastids, green;
and (3) chromoplastids, yellow, orange or red.

Nucleus. — All typical cells have a definite nucleus. It
is wrong to regard the nucleus as the "seat of life" of the
cell, for other portions of the cell are all-important, but it is a
most essential part of the cell. If the nucleus is separated
from the cytoplasm by artificial means, the cell dies. Its
presence is needed, it seems, to stimulate respiratory activity.
Moreover, reproduction of the cell — its division to form two

FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 9

cells — involves definite nuclear changes, which has led to
the opinion that hereditary characteristics are carried by
nuclear matter. The structure of the nucleus is indeed
complex, and there is a wonderful chain of changes that
it goes through at the time of cell division.

Protoplasm. — In 1840, Hugo von Mohl drew attention to
the fact that the slimy substance in the plant cell was
responsible for its life, and that as soon as it was removed,
the cell no longer had the properties of livingness. The
name protoplasm was applied to the living portion of the
plant cell. Somewhat later, 1850, Ferdinand Cohn, gave
positive evidence of the identity of the living material
(protoplasm) in plant cells, and of the living material (so-
called "sarcode") in animal cells.

If we examine a small bit of protoplasm under the micro-
scope we see that it is a semi-transparent, jelly-Uke, 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.

CHAPTER III
ROOTS

Development of Root Systems. — The root system of a
plant is the entire collection of roots. Let us trace out the
development of different root systems, starting with the
seed. If we examine soaked grains of wheat, or bean seeds,
or beet seeds, we observe that there is a young root already
formed within the seed. Three germinating stages in wheat
are shown in Fig. 2. The one principal root or primary
root we see in the grain is the first to appear. It breaks
through the root sheath (coleorhiza) which remains as a
collar about the root where it breaks through the grain coat.
Very soon two lateral roots appear; hence the primary root
system or temporary root system consists of a whorl of three
roots. Since these three roots were in the seed in the
embryonic condition they are called seminal (seed) roots.
The secondary roots appear in whorls at the joints on the
stems some distance above the three temporary roots. The
first whorl of permanent roots in wheat is generally about i
inch below the soil surface, no matter at what depth ;the
grain was planted (Fig. 3). One whorl of roots after
another is formed above the first one, and as a result there is
built up a fine network of roots, with their branches. A root
system such as described in wheat is called a fibrous root
system.

We spoke above of the three seminal or seed roots, and the
development of whorls of roots from the nodes above as
shown in Fig. 3. Roots not arising from the seed or as

ROOTS II

branches of seed roots, but from stems or leaves, are called
adventitious roots. Hence the fibrous root system of wheat,
and of all the other cereals and grasses, is in reality composed
of roots that develop adventitiously. Adventitious root

coleophle

Fig. 2. — Three germinating stages in wheat.

systems may appear under a variety of conditions. When
young onion "sets" are placed in the ground, a set of roots
(adventitious roots) appears at their bases. If young one-
year-old twigs or stems (cuttings) of apple, raspberry, willow,
geranium, carnation, chrysanthemum, rose, or of many other
economic plants are placed in damp soil or sand, adventi-

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

ground line

Fig. 3. — In spite of the fact that the grain of wheat was planted at too great a
depth, the permanent roots were formed at about i inch below the soil surface.

leaves will even develop adventitious roots from cut or
wounded leaf veins. This is true of such leaves as begonia,

ROOTS

gloxinias, and bryophyllum. In the black-cap raspberry
and in dewberries, a shoot (stem) may bend over by its own
weight, and where it strikes the ground, develop adventi-
tious roots, and thus secure a foothold. When once the
tip has rooted well, the stem may be cut loose from the

GROUND

L.I NE

.\::;\

Hcf--

Fig. .\. — Tap-root system of youny^ sugar beet. (Maxsou.)

parent stem and such rooted ti[).s 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 develo[)s in such plants

14 BOTANY OF CROP PLANTS

as the beet, radish, turnip, parsnip and carrot. In the germi-
nation of the beet seed, for example, the primary root pushes
out, takes a straight downward course, and gives off a few
lateral roots. Hence, the primary root system of the beet
consists of one main root extending downward, with a few
fme 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, dandehon, red clover, and many
other plants is called a tap-root system.

The Work of Roots. — A root system absorbs, anchors, and
serves as storage organ. The small, young, tender roots, with
their root hairs, are largely absorption roots, but as the plant
gets older, new absorptive roots are continually being formed,
while the older ones become thick and woody and serve mainly
as anchorage organs. Familiar storage roots are those of
the beet, carrot, turnip, parsnip, sweet potato, and dande-
lion. The food material stored up by such plants for their
own use furnishes a large proportion of the food supply of
man. Irish potatoes (tubers) are not roots, but stems, and
hence their discussion will be reserved for the proper section
in the book.

Effect of Environment upon Character of Root System.—
It is noted, when roots make a vigorous growth, as they will
under favorable soil conditions, that there is a very extensive

ROOTS

,plerO),-Ti.

endodermis

perl6/em
Aerwaloqen

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
of members, each with
more or less distinctive
characters. . Roots have characteristics which stand out
in quite marked contrast to those of other plant members.
Roots do not give off their branches in a regular order,
as stems do. They do not bear buds, except in very rare
cases. Roots usually bear a root cap (Fig. 5) which pro-
tects the growing point, while the growing point in stems

region of ^

ariatesir
iellmu/tif^ica

Fig. 5. — Median lengthwise section of
the apex of a root of barley. (After
Slrasburger.)

l6 BOTANY OF CROP PLANTS

is either naked or surrounded by modified leaves (bud
scales). There are other characters which will be mentioned
further on.

Classification of Roots Based upon Their Medium of
Growth.^ — The medium of growth of most roots is soil. Such
roots may be called soil roots. It is customary for us to
think of the root system of a plant as growing in the soil,
just as we associate the shoot system with the air above
ground. However, not all roots live in the soil, and not all
shoots hve in the air. There are water roots, and air roots,
as well as the ordinary sort, soil roots. Water roots occur
in such floating plants as the duckweeds, water hyacinth
{Eichhornia speciosa). Water roots produce but a few
branches. They possess no root hairs; absorption takes place
through any cells on the surface. Air roots occur in many
plants, such as corn (Fig. 56, B), Virginia creeper, tropical
orchids, the banyan and other species of Ficus. Air roots are
well shown in corn. In addition to the ordinary underground
(soil) roots, corn develops aerial (air) roots, the so-called prop
or brace roots (Fig. 56, B). These arise at successive levels
above the surface, extending obliquely downward. As aerial
roots, they are unbranched, but they branch profusely when
they strike the soil. They have the role of absorption, then,
as well as anchorage. In the banyan, for example, the air
roots are often very large, and arise from branches far above
the ground. They grow downward, and when they strike
the ground, become firmly attached, and act as a support
or prop to the heavy branches.

Hence, we learn that not all roots have soil as their medium
of growth, but that air and water may be the media for some.

Structure of Roots. — ^Let us cut a median (middle) length-
wise section of a young root. It will appear as in Fig. 5.
We shall see then that the root has a cap of loose cells at the

ROOTS

tip. This protective structure is called the root cap. Just
back of the root cap is the region of greatest cglljnultiplica-
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, (jX.
dermatogen, an outer layer or
layers; (2) plerome (axis); and Q}.
periblem^etween the dermatogen
and plerome. The dermatogen
becomes the epidermis, the plerome
the stele or central cylinder, and
the periblem the cortex. It is
often possible to strip the cortex
and epidermis from the central
cylinder, which is composed of
tough, fibrous tissue. ' 4^

The cortex (Fig. 6) is composed
of large, thin-walled cells, which
do not fit closely together, but
leave air spaces (inter-cellular
spaces) between. The innermost
cortex layer is called the endo-
dermis. The outer cortex cells
may become prolonged to the side
to form root hairs. The central
cylinder or stele (Fig. 6) is bounded
by a single layer of cells, the pericycle, which lies adjacent
to the endodermis. Within the stele are found alternat-
ing bundles or strands. The woody, water-conducting bun-

FiG. 6. — Cross-section of a
young root of Phaseolus mul-
tiflorus. A, pr, cortex; m,
pith; X, stele or central cylin-
der— all tissue within the peri-
cycle, inclusive; g, primary
xylem bundles; b, primary
phloem bundles. B, cross-
section of older portion of
root; lettered as in ^; b',
secondary phloem. (After
Vines.)

BOTANY OF CROP PLANTS

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 pith or
medulla.

Side roots arise from the outer edge of
^j, the stele (central cylinder), and push their
way through the cortex and epidermis
(Fig. 7). This method of origin of side
branches is characteristic of roots. In
stems the, side branches arise from the outer
part of the cortex (Fig. 15). Branch roots
are said to have an endogenous origin,
while branch shoots (except those in mono-
cots) have an exogenous origin.

As the root grows older, new xylem and
phloem are formed, and by and by, it be-
comes very tough and woody, serving as an
efficient anchorage organ.

Root Hairsn^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

Fig. 7. — Young root of white lupine showing origin
of lateral roots from the stele. {After Gager.)

ROOTS

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-hke rootlets as branches of larger roots. These fine
"hair roots" are sometimes mistaken for root
hairs. But, closer examination, in which a
hand lens may be necessary, shows us that
these hair roots are the bearers of root hairs.
In fact, root hairs are found only on the
smallest and youngest rootlets.

Root-hair Zone. — Root hairs do not grow
along the full length of a rootlet, but occupy
a definite zone, designated the root-hair zone.
This is clearly seen in young 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- ^]°- 8.— Wheat

° ' seedling snowing

times partially surrounds, the soil particles soU particles cUng-
with which it comes into contact, thereby nTtethltTh^root
forming a close connection with the water cap is free of root
and solutes that form a thin film around
each soil particle (Fig. 9). Furthermore, the root hairs
become mucilaginous, and this, along with their partial sur-
rounding of particles, explains the presence of the mass of
soil particles that clings to rootlets in the root-hair zone.
Root hairs are short-lived, persisting for only a few days or

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 line the walls, and the nucleus usually occupies a posi-
tion near the apex. The central vacuole is large, and is filled
with cell sap. The cell sap contains water, and various or-
ganic and inorganic substances in solution.

Effect of External Factors upon Development of Root
Hairs. — Most air and water roots have no root hairs. Soil
roots, such as those of conifers, oaks, and others that are
surrounded by a fungus (mycorrhizal growth) possess no root
hairs. In the case of ordinary soil roots, root-hair develop-
ment is usually meager in very wet soil. Corn roots develop
root hairs in abundance in moist air, but none at all in water.
The absence of root hairs in very wet soil, and in water, is
probably to be attributed to poor oxygen supply. In a

ROOTS 21

water-soaked soil, the air spaces are 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, corn, rice,
sorghum, and also such common crop plants as buckwheat,
beans, peas, tomatoes, melons, etc., have annual roots.
Biennial plants live two vegetative periods. Common
biennials are beet, cabbage, carrot, and parsnip. From the
seed of beet, for example, there is developed the first season
a large fleshy tap root, and a short crown from which the
leaves arise. This fleshy structure ("beet"), stored with
food, rests over the winter, and the next growing period
sends up stout, branching stems to a height of 3 or" 4 feet,
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 live from year to year, increasing in size each season.
Such plants are perennial in habit. In most cases the length
of life of roots is the same as that of the shoot system. How-
ever, underground perennial stems, such as are possessed
by quackgrass, Canada thistle, false Solomon's seal, etc.,
may have annual roots.

CHAPTER IV
STEMS

Development of Shoot System. — When a grain of wheat
germinates, the primary root is the first to appear. Very
soon two lateral roots make their appearance, forming a
primary root system of three roots. Also, the young stem
(Fig. i) elongates, and there is formed the first shoot
system of the plant. Elongation of the stem continues by
growth at the tip, where the cells are young and active.

It is observed that the stem is divided into sections (inter-
nodes) (Fig. 25). The nodes, the enlarged joints between
the internodes, give rise to leaves, and if we follow the wheat
plant through its hfe, we observe that the stem terminates
in an inflorescence (flower cluster). Now, in addition to the
one main stem that arises as a prolongation of the embryonic
stem in the seed, branches arise from the lower nodes. These
branches arise in the axils of the lowermost leaves, in most
cereals. In cereals, this branching is known as " stooling"
or ^^ tillering" Common cereals invariably produce a num-
ber of tillers or branches from the primary stem, and these
in turn other tillers (lateral branches), so that under favorable
conditions several dozen culms may result from a single seed.
In the wheat plant, two or three weeks old, three or four
buds (young stems) may be found, one in the axil of each
leaf. Tillering results from the outgrowth of these lateral
buds. Hence, as a result of the elongation of the main
growing point, and of the lateral growing points into lateral

STEMS 23

branches of the primary stem, there is built up a shoot sys-
tem, with its leaves and flowers.

Buds. — A bud is an undeveloped stem; it is simply a young
shoot. In an ordinary shoot, an apple or peach twig'^for
example, the internodes are considerably elongated. In
rapidly growing water sprouts, internodes may be several
inches in length. A bud is a very short, young shoot in
which the internodes 'are few or are exceedingly short.
That a bud is a young, individual shoot in itself is shown
by the fact that buds may be removed from a branch
and applied to the surface of the growing tissue (cambium)
of another branch (stock) and successfully grown there. In
fact, bud grafting is a common horticultural practice. The
tip of the bud is usually protected by a series of overlapping
scales (bud scales), which are in 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) mixed buds.
If we open up a leaf bud, we find a very much shortened axis
or stem bearing a number of small leaves. As the leaf bud
is a young shoot, it may as properly be called a branch bud.
That is, it elongates into a branch which bears leaves. The
new shoot, just as the old one from which it came, ends in a
bud, and in the leaf axils other buds arise. If we open up a
flower bud, we find one or more young flowers. In plums,
for example, the number of flowers in a bud varies from one
to five, two and three being the most common numbers
(Fig. 166). Mixed buds contain both flowers and leaves.
The terminal buds at the ends of the short "spurs" in the
apple are mixed buds (Fig. 153).

It is not always possible to distinguish leaf from flower

24 BOTANY OF CROP PLANTS

buds by their external appearance. In some cases, however,
they have a different shape. In the apple, for example,
fruit buds (here, really mixed buds) are rather thick and
rounded, while leaf buds are smaller and more pointed.
In all plums, the flower buds are lateral, and usually stand
out at an angle of about 30°, while leaf buds are more ap-
pressed to the stem.

Buds may be classified as to their position on the stem into:
(a) terminal, ih) lateral or axillary, ic) 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 He buried within the tissue in
a latent condition. Such a bud may be called into activity
later in the life of the plant and come to the surface. It
would appear to be endogenous in its origin, while in reality
it is exogenous. Irregular branching may result from the
development of dormant buds, or as is more commonly the
case, from the development of adventitious buds.

STEMS

Buds may be classified
as to their arrangement on
the stem into : {a) alternate,
(b) opposite and (c) whorled.
It is well to keep in mind
that bud arrangement is
the same as leaf arrange-
ment, for the reason that
buds normally develop in
each leaf axil. Further-
more, as leaf buds develop
into shoots, the method of
branching, and hence the
form of the plant, is largely
determined by the bud
arrangement.

When one bud occurs at
each node, they are said
to be alternate (Fig. 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-

terminal leaf -bud

flower-buds
\sfipule-scar

llenticels

latent hud--

one year'
old branch

■ lateral leaf buds

■ terminal bud- scar

flower-bud-scars

:o. — Cottonwood twig two years
old. {After Longyear.)

26 BOTANY OF CROP PLANTS

ence really exists can be well shown by removing branches or
buds and growing them into independent plants. If we do
this we will find that the individuals from the separate buds
may vary in such respects as habit of growth, manner of
branching, nature of foHage, form, color, texture and yield
of fruits.

Nearly all our fruits are multiplied by bud propagation
(asexual parts) and not by seed (sexual parts) ; and many of
the varieties of fruits now in cultivation are in reality bud
varieties or " sports." A certain branch on a tree is observed
to differ from the rest in some marked respect; and this
branch is taken off and propagated as a new variety.

General Characteristics of Steins. — ^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

STEMS

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.

W^sg'

Fig. II. — Section of the lenticel of elder. (After Slrasburger.) 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-

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 foHage leaves and flowers. Both

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 different from the ordinary sorts that they are scarcely
recognizable as stems, and are identified as such, only by
careful study of their origin and structure. Among such
stems are the following:

I. Rootstocks or Rhizomes (Fig. 12). — These are under-
ground, horizontally elongated stems. The rootstocks or
rhizomes of Canada thistle are excellent examples. They
bear reduced, scale leaves at the nodes. Lateral buds arise
in the axils of these leaves, just as described in the cotton-
wood twig — a typical stem. They grow in length from a
terminal bud, which is unprotected by tough scales. Adven-
titious roots are produced at the nodes. Rootstocks are
efficient organs in the spreading of a plant. Here is a
method of reproduction other than by seeds. Usually,
aerial stems from the lateral buds of the rootstock are pro-
duced; they may die back to the ground each fall. The
plant lives over the winter by means of the rootstocks.
Hence, rootstocks or rhizome-bearing plants are perennial.
Many of our worst weeds are perennials from a rootstock.
We may prevent such plants from going to seed, but in spite
of this, and the cutting back of the leafy shoots, new shoots
are sent up from the rootstocks. Furthermore, if the root-

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

i/jp— decurrent

leaf base

xhizome

Fig. 12. — Portion of a sprouting potato tuber.

shoots as soon as they appear, may succeed in starving out
the rootstock after a time. The period of time depends upon
the amount of stored food material in the structure. This
method of eradication is based upon the knowledge that the

STEMS

food of the plant is manufactured in the chlorophyll-bear-
ing (green) cells above ground.

2. Tubers. — These are fleshy, underground stems. The
best example is common Irish potato. Although the potato,
ordinarily, would not be considered a stem, still if we follow
through its development, and examine its structure, we are
convinced that it is stem (Fig. 12). When we plant a
slice of a potato, "sprouts" are soon sent out from the
"eyes." These sprouts, with their nodes, and internodes,
and their scale leaves, are quite obviously horizontal under-
ground stems (rhizomes). Soon,
the tip of a rhizome begins to en-
large, and a potato is formed;
hence, the potato is seen to be a
simple enlargement of the tip of an
underground stem. Furthermore,
examination of the tuber reveals
the presence of a terminal bud
("seed end" of the potato), and
lateral buds along the sides. The
buds are the so-called "eyes."
In an elongated potato, we may
be able to detect the spiral ar-
rangement of the buds. Lenticels
may also be observed on the corky
layer (skin) of the bark of the
potato.

A section of a tuber reveals a stem structure. The three
principal parts of an ordinary stem are bark, wood and pith.
This is shown in a cross-section of an ordinary twig (Fig. 13).
In the potato, these three distinct zones are visible, as indi-
cated in Fig. 236. Hence, we see that the potato is in 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.)

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
exempHfied in gladiolus.
Corms are usually flattened
from top to bottom, and bear
a cluster of thick fibrous
roots at the lower side, and a
tuft of leaves on the upper
side. Corms are storage
organs.

5. Runners (stolons). —
These resemble rhizomes in
that their direction of growth
is horizontal. In the straw-
berry plant, the branches that arise from the axils of the
closely set leaves are called "runners." They are slender
stems, growing along the ground surface; they have long
internodes, and produce leaves, flowers and roots at the
nodes. Runners are used as a means of propagating the

Fig. 14. — Median lengthwise section
of common onion bulb.

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 hanas 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 (undifferentiated tissue).. Although they
3

BOTANY OF CROP PLANTS

are similar in appearance, it is quite evident that they are
capable of developing into different tissues. Just back of

r Xylemfroni the procamblun

Cylem from the procamblum xvlem f rom the cambium

Xylem from the cambium .phloem from the procamblum and cambium

rhloem from the procamblum and cambium miuouiiium <= w

Fig. 15. — Diagram showing the evolution of tissues from the primordial
meristem down to the beginning of cambial activity. {After Stevens.)

the growing point, we note that the cells have differentiated
into three main regions: epidermis, ground meristem, and

STEMS

:::^^

OOOo

%oc>o

ooot^o

-S=^^

OOooO

==-__

ill

.=^

.S:

er.^1!^

o°o?S

^^5=--

So^'^O

OO o°

OOoO

,==»

procambium strands. These three regions are best shown
in a cross-section (Fig. 15). In a little older portion
of the stem, such as shown in a section further back
(Fig. 15), further differentiation
has taken place, which changes
involve the ground meristem and
the procambium. The vascular
bundle is composed of three re-
gions : phloem, cambium and xylem.
The center of the stem is made up
of large, loosely fitting cells which
constitute the pith or medulla.
Radiating from the medulla out
between the vascular bundles are
a number of cells which make up
the medullary ray.

Dicot Vascular Bundle. — De-
tailed examination of a dicot vas-
cular bundle in cross- and longitu-
dinal sections shows each of its
three parts to be made up of
characteristic structural elements.

Phloem. — In the phloem are
sieve tubes, companion cells, and
phloem parenchyma. Each sieve
tube is a single cell, much elon-
gated and modified for conduc-
tion. The end walls of sieve tubes
(Fig. 16) are thickened, and per-
forated by a great number of holes,

and thus resemble a sieve. Each sieve tube is adjoined by
a single row of small cells, the companion cells, which run
parallel to it. Phloem parenchyma cells are somewhat

F ' "^^

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

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 Hfe processes
for which a nucleus seems necessary.

3. Phloem Parenchyma. — The cells of this region store food
material or conduct it short distances in the stem.

Cambium. — The cambium layer is composed of one or
more rows of small cells, flattened in planes that run at
right angles to a radius of the stem. They are thin- walled
cells, rich in protoplasm, and capable of rapid cell division
and growth. The cambium is in fact the growing layer of
the stem. In grafting, one stem, the scion, is inserted
into another stem, the stock, in such a way as to bring the
two cambium layers together. The cells of these layers
possess the power of growth, and after a time there is a
union.

Xylem (Wood). — The chief structural elements of the
xylem or wood portion of the vascular bundle are: tracheal
tubes, tracheids, wood fibers and wood parenchyma. The
tracheal or water tubes are long, large, tubes with thick
walls. They have been formed by the elongation and en-
largement of rows of cells, the common end walls of which
have totally or partially dissolved, leaving a duct of consider-
able length. The" walls of the tracheal tubes become thick-
ened, and the thickening material {lignin) is laid down on
the inside of the walls in various patterns.

STEMS 37

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

1. Annular Tracheal Tubes. — 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 manlier 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. Trache"d

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; {b) 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; {b} and
also conduct them short distances.

^8 BOTANY OF CROP PLANTS

4. Wood Fibers.— Give strength to the stem.

Growth in Thickness of Dicot Stem. — Medullary ray cells
give rise to cambium that joins with the cambium in the
vascular bundles. Thus there is formed a continuous cam-
bium ring (Fig. 15). At the end of the first year of growth
or the beginning of the second, another sort of cambium,
called cork cambium, is differentiated in the outer cortex.
Growth in thickness of the stem consists then in the produc-
tion and growth of new cells from: (i) cambium of vascular
ring, and (2) cork cambium. The cambium cells of the
vascular ring may differentiate into xylem, or phloem, or
remain cambium. Each cambium cell divides by a wall
which is parallel with a tangent to the outside of the stem.
If the inner cell resulting from the division becomes a xylem
element, the outer usually remains cambium. On the other
hand, if the outer cell resulting from the division becomes a
phloem element, the inner remains cambium. Hence, by a
division of cambium cells of the vascular ring, new xylem
is laid down on the outside of the old xylem, and new phloem
is laid down on the inside of the old phloem. Not only
do the vascular bundles grow in a radial direction, but also
somewhat laterally. This lateral growth of existing vascular
bundles, together with the formation of new ones between
the old ones, brings about a narrowing of the medullary rays,
so that in an old stem they appear as mere 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, and to secondary cortex. Hence, each year, there
are produced in the dicot stem:

STEMS

1. Wood, on outside of old wood.

2. Phloem, on inside of old phloem.

3. Cork, on inside of old cork.

4. Secondary cortex, on outside of old cortex.

A two-year old woody dicot stem has the following general
structure :

1. Bark, consisting of the following parts in order from
outside to inside: Cork, cork cambium, secondary cortex,
primary cortex, primary
phloem, secondary phloem.

2. Cambium of vascular
bundle.

3. Wood, consisting of
two layers, the youngest
toward the outside.

4. FUh.

5. Medullary rays, each
ray of several rows of
thin-walled cells running
from the medulla to the
outer edge of the phloem.

Monocot Stems. — The
corn stalk is an excellent
type of a monocot stem.
In this, as shown in cross-section of the stem in Fig. 18,
the vascular bundles (fibers) are scattered throughout the
ground tissue. They do not form a definite "vascular ring"
as in dicot stems. Moreover, the vascular bundles of most
monocots do not possess cambium, as in dicot stems. Hence,
new phloem and xylem are not produced each season, and
consequently there are no annual rings formed. Growth of
monocot stems results from (i) simple enlargement of cells
derived from primary meristem tissue, and in some instances

Fig. 18. — Cross-section of cornstalk
stem; a, epidermis; b, cortex and peri-
cycle; c, ground tissue. (After Stevens.)

40 BOTANY OF CROP PLANTS

from (2) the formation de novo of vascular bundles from
cells that have retained their meristematic power.

Annual Rings. — An annual ring, as generally understood,
is one year's growth of wood (xylem). The ring varies in
width, depending upon the time in the life of the plant it was
formed, and upon seasonal climatic conditions. Further-
more, it is known that some trees grow rapidly, producing
wide annual rings, while it is a specific character of others
to grow slowly, i.e., produce narrow annual rings.

There is usually a marked difference in the wood formed in
the spring and early summer, and that produced in late
summer and fall. In early or so-called "summer wood,"
tracheal tubes are large and quite numerous; in late or
"autumn wood," tracheal tubes are smaller and fewer, and
tracheids and wood fibers are relatively more abundant.
Hence, "autumn wood" has more strength than summer
wood. It is readily seen that the autumn wood of one year
(say 1916) is adjacent to the spring wood of the following
year (19 17). "Soft wood" is usually one which grows
rapidly, and is difuse 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 Hne
is the cambium zone.

STEMS 41

The Work of Stems. — (i) The stems of trees, shrubs and
common herbs are mainly concerned in the conduction of
water and solutes from the soil, and of food materials. The
need for a conductive system first arose in the plant kingdom
when the food-making organs of the plant became elevated
above the soil or water surface. (2) The stem also is a
support to the other organs of the plant, and it brings into
display the leaves, and flowers. The leaves are brought
into a position where they may receive the light to advantage,
and flowers are placed where their pollen may be disseminated
by wind or bees, and seeds may be more easily spread. (3)
In addition to conduction and support, stems may store
food material, water and various waste products. In our
woody perennials, such as the apple or peach, for example,
an abundance of food material is stored during the winter
in the medullary ray cells, also, in wood parenchyma, and in
that portion of the pith adjacent to wood, and sometimes
in all of the pith cells; portions of the phloem, and cortex
may also store food. The stems of such plants as the giant
cactus, and other cacti, store large quantities of water.
Some stems, such as the potato tuber, bulb, corm and root-
stock, are heavily loaded with stored food material. (4)
Young stems that contain chlorophyll in their outer layers
possess the power of manufacturing carbohydrates, just as
do green leaves.

CHAPTER V
LEAVES

Development of Leaves.^ — ^Leaves appear at the growing
point of a stem, as lateral protuberances (Fig. 15) consist-
ing at first of a shapeless mass of cells. We call this group of
cells the primordial leaf. By further cell division and dif-
ferentiation (becoming different from each other) of these
few cells the adult leaf arises. In the embryos of seeds
the first few leaves are already formed, and even in this
early stage may bear some resemblance in shape to the
adult leaves.

Parts of Leaf. — Most leaves have two distinct parts:
hlade and petiole (leaf stalk). Some leaves, as those of peas
and beans, have two small, leaf-like structures at the base
of the petiole. These are stipules (Fig. 19). The petiole is
sometimes absent, the blade being mounted directly on the
stem. Such a leaf is said to be sessile. Vascular bundles run
from the stem out through the petiole into the blade, where
they branch to form the network of veins. The veins not
only carry water, solutes and food materials, but also form
a framework for the softer tissue of the leaf.

Kinds of Leaves. — It is possible to classify leaves in many
different ways. Common green leaves that we are all
familiar with are usually called foliage leaves. They are the
chief food-making organs of all ordinary plants. However,
there are many leaves that do not possess green coloring
matter (chlorophyll) and hence, have no food-making power.
42

LEAVES

tendrils

-jleajleh

As examples of the latter, may be mentioned the small
scale leaves on underground stems, the scales enwrapping
the growing point in buds, the bracts in grass inflorescences,
and the petals, stamens and car-
pels of flowers.

We look upon ordinary foliage
leaves as the most common, and
hence "normal," sorts of leaves.
We would regard scale leaves,
bracts, bud scales, and flower
parts as "modified" leaves.

Leaves may function as (i)
food-making organs (foliage
leaves), (2) protective structures
(scales), (3) reproductive organs
(floral organs), and (4) as storage
organs. The fleshy leaves that
make up the bulb of onion are
good examples of leaves used for
storage.

Foliage leaves are either par-
allel-veined or netted-veined. In
leaves with parallel venation, there
are many veins, about, equal in
size, running parallel, and joined
by inconspicuous veinlets. This
type of venation is characteristic
of the leaves of. grasses, sedges,
rushes, liHes and most all other
monocotyledonous plants. In
leaves with netted venation, which
is so well illustrated in leaves of apple, oak, maple, potato,
cabbage and other dicotyledonous plants, there are a few

'^stipules

Fig. 19. — A single compound
leaf of sweet pea.

44 BOTANY OF CROP PLANTS

prominent veins from which arise numerous minor veins,
thus forming quite a conspicuous network.

Leaves are often classed as simple or compound. The apple
leaf is an example of a simple leaf (Fig. 1 59) . 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
paHsade 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 developa thicker cuticle under arid conditions

LEAVES

45
A thick

than when growing where there is ample water,
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

46 BOTANY OF CROP PLANTS

described above is typical of dicot leaves growing in situa-
tions with a moderate water supply. Water leaves are
thin and have no palisade tissue. 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
rows of palisade cells. Palisade may develop on both upper
and lower surfaces. Some leaves have palisade tissue from
epidermis to epidermis. The thickness of leaves growing in
arid conditions may also be, in part, the result of the de-
velopment of a very thick cuticle.

The Work of Foliage Leaves. — ^Leaves are very important
organs of the plant. We are all familiar with the injury to
a plant that results from defoHation 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

LEAVES 47

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

In addition to their important work of carbohydrate
synthesis, the synthesis of the fats, amides and proteins is
carried on to a large extent in leaf cells. We may truly say,
then, that leaves are the food-making organs of a plant.

Leaves are also the chief transpiring (water-losing) organs
of the plant. Practically all of the water that escapes from
a plant passes out through the leaves, chiefly through the
stomata. When in a healthy growing condition, there is a
continuous stream (transpiration stream) of water from the
roots to the leaves.

The leaves of many succulent plants, such as Agave,
Russian thistle, salt wort, stone crop, and others serve as
storage places for water. Agave leaves may also store
food. The onion bulb is made up of a very short stem bear-
ing numerous, overlapping, fleshy leaves in which consider-
able quantities of food are stored.

The leaves of the sundew {Drosera), and pitcher plants
{Sarracenia and Nepenthes) are highly modified as special
organs that catch, digest and absorb insects.

CHAPTER VI

FLOWERS

Parts of Representative Flower. — A representative flower

such as shown in Fig. 21
has the following parts
taken in order from the
outside to the inside:

1. Calyx, made up of
sepals, which are green,
and enclose the other
flower parts in the bud.

2. Corolla, made up of
petals, which are usually
the colored portions of the
flower.

3. Stamens, each made
up of a stalk or filament
at the tip of which is
the anther, bearing pollen

5"*^v^ V^^X^Q ^ Pistil, which has a

,^ swollen basal portion, (i)

\^^y\j If . the omr'^, (2) a style, slen-

^^^^^^"^^ (k W 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.

FLOWERS

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 are many different sorts of flowers
in the families of seed plants. They differ widely in size,
form, color, and in the shapes of the various parts.

Development of the Flower. — The primordia of flower
parts arise as protuberances from the young receptacle (Fig.
15). As a rule, the sepals, petals, stamens and carpels

Fig. 22. — Cross-section of a mature lily anther. The pairs of pollen cham-
bers unite to form two pollen sacs, filled with pollen grains; s, modified epi-
dermal cells at line of splitting. (From a Text-book of Botany by Coulter,
Barnes, and Cowles. Copyright by the American Book Company, Publishers.)

appear in the order named, as described in the case of the
apple flower on page 366. This order of floral succession is
said to be acropetal. Although this is the prevaiHng order,
there are different types. For example, in some mustards
the petals are the last to appear, and in some roses the carpel
primordia appear before the stamens.
Stamens. — Ordinarily, the anther is held upon a filament

50 BOTANY OF CROP PLANTS

or stalk. When the filament is absent, the anther is said
to be sessile. A cross-section of an immature anther is
seen to have four chambers or locules, each with a number
of pollen mother cells; each pollen mother cell normally
divides to form four pollen grains. As the anther matures
the pairs of locules unite, thus forming two pollen sacs in
each anther. Finally, each sac splits open (dehisces) allow-
ing the pollen to escape (Fig. 22).

Matiire Pollen Grain. — When the pollen grain is mature,
it consists of a wall surrounding a protoplasmic mass, the
essential parts of which are a tube nucleus and a generative
nucleus. At the time of pollen germination the latter di-
vides into two sperm or male nuclei.

Pistil. — The pistil usually consists of an ovary, style and
stigma. The seeds are borne in the ovary. A cross-section
of a simple ovary shows it to have one locule or chamber
with one or more ovules attached to the wall. The tissue to
which the ovule or ovules are attached is the placenta.
A compound ovary (Figs. 21 and 131) usually has two or
more compartments, with an ovule-bearing tissue (placenta)
in each. We may also speak of the pistil as simple or com-
pound. A simple pistil has one carpel, which is in reality a
modified leaf bearing one or more seeds. A compound pistil
has two or more carpels. When the carpels are separate,
as in the strawberry (Fig. 151) the flower is said to be
apocarpous; when united, as in asparagus (Fig. 99),
syncarpous.

Ovule. — Fig. 23 shows an ovule just before fertilization.
A central mass of tissue, the nucellus, is surrounded by an
inner and an outer integument, except for a small opening,
the micropyle. Within the nucellus is the embryo sac, at
this stage consisting of eight nuclei: two synergids, one egg
nucleus, three antipodals, and two polar nuclei. They occupy

FLOWERS

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.

pollen iube

eqg nucleus

pericarp
ouier /niefi/item
innerhhijvtneni

nucellvi-'
embrno sac -'

polarnuc/ei
aniipodals

Fig. 23. — Diagram of a simple pistil as seen in lengthwise section showing a
single ovule just prior to fertilization.

This is termed autogamy or close pollination. Or, pollen
may be carried from an anther to a stigma of another flower
on the same individual plant. This is called geitonogamy.
Again, pollen may be transferred from an anther to a stigma
of a flower on another individual plant. This is termed

BOTANY OP CROP PLANTS

xenogamy, or cross-pollination. Insects, wind and water are
the chief agents in the spread of pollen.

Fertilization. — Fig. 23 is a diagram of an ovary with a
single ovule cut lengthwise. It shows a stage of develop-
ment of the ovule about at the time when the pollen grain
has reached the stigma. As has been said, the mature pollen
grain consists of a protoplasmic mass surrounded by a rather
thick wall. Three nuclei (Fig. 24) constitute
the important structures in the pollen grain.
It absorbs water and nutrient materials from
the stigmatic surface, and grows by sending
out a tube, known as the pollen tube. The
tube grows downward through the stigma,
sometimes in a tubular passage, or when
necessary, secreting enzymes which digest
(render soluble) the walls of cells that are in
its path, at the same time deriving nourish-
ment from this digested material. As the
tube grows, the three nuclei keep pretty close
to the tip, the tube nucleus in the lead, with
the two sperm nuclei (male gametes) follow-
ing. The tube finally reaches the ovule,
takes a course through the micropyle and comes into con-
tact with the nucellus. This nucellar tissue is penetrated,
and after dissolution of the wall at the tip of the pollen tube,
the three nuclei are discharged into the embryo sac. The
tube nucleus is reabsorbed. One sperm nucleus unites with
the egg nucleus (female gamete) to form the zygote, a nuclear
mass which contains both the characters of the plarit fur-
nishing the pollen - (paternal characters) and those of the
plant fertilized (maternal characters). The union of the
male gamete (sperm nucleus of pollen tube) with female
gamete (egg nucleus of embryo sac) is fertilization. It is a

■tube nucleus

Fig. 24. — Ger-
minating pollen
grain. {After
Bergen and Cald-
well.)

FLOWERS 53

sexual process. It is seen to differ fundamentally from
pollination which is simply a mechanical -process. The
fertilized embryo nucleus now develops into a young plant
(embryo). The synergids and antipodals are usually dis-
organized. In grasses and lilies and some other plants, so-
called double fertilization has been observed. One sperm
nucleus has been accounted for, as uniting with the embryo
nucleus. The other unites with the two polar nuclei of the
embryo sac. The body resulting from this triple fusion also
carries both maternal and paternal characters. It grows
and develops into the endosperm of the seed. Immediately
following fertilization, there is a series of changes not only
in the ovule which results in a seed, but in the ovary wall as
well.

Just one pollen tube penetrates the embryo sac to bring
about fertilization. Many pollen tubes, even hundreds,
may penetrate the style, although comparatively few may
function normally. Those which do not, wither and die.
We may be sure that every ovule that develops into a seed
has been visited by one, and only one, pollen tube.

Placentation. — We said that the placenta is the tissue in
the ovary to which the one or more ovules are attached. It
is traversed by vascular bundles from which branches are
given off to the ovules. In currants and gooseberries (Fig.
129) the placentae are on the ovary wall. Such placentation
is said to be parietal. In lilies (Fig. 31^), the placentation
is axial, or central, that is, the placentae are on the ovary
axis. A third kind of placentation is the free central, in
which^the ovules are attached to an up-growth of the floral
axis in the center of the ovary, which is not connected to
the ovary wall by radial partitions.

Symmetry of Flower. — A flower such as the apple, cherry
or asparagus can be divided into two approximately sym-

BOTANY OF CROP PLANTS

metrical halves by any diameter (Figs. 156 and 162). Such a
flower is said to be radially symmetrical, or acfinomorphic,
or regular. Contrast this symmetry with that in such flowers
as the pea or bean (Fig. 1 72^), in which there is but one plane
through which the flower can be divided to separate it into
two symmetrical halves. Such a flower is said to be bi-
laterally symmetrical, or zygomorphic, or irregular.

Relative Positions of Flower Parts. — In the gooseberry or
currant flower (Fig. 129), for example, the ovary is below
the stamens, corolla, and calyx, and is said to be inferior. . A
flower with an inferior ovary is said to be epigynous (above the
gynoecium or carpels) . When the calyx, corolla, and stamens
are inserted on the receptacle below the ovary, the ovary is
superior, and the flower hypogynous (below the gyncecium).
The flowers of mustards are hypogynous. There is a third
intermediate type of flower, well illustrated by the cherry
(Figs. 157 and 163), apple (Fig. 157), etc., in which the
petals and stamens are inserted on a calyx rim and arise at
about the level of the ovary. In such a case the ovary is
half-inferior or half -superior , and the flower perigynous
(around the gynoecium).

Union of Flower Parts.- — In the primitive flower type, such
as the buttercup, the sepals, petals, stamens and carpels are
all separate and distinct. A more or less complete union of
the parts of each set of floral leaves may take place. For
example, in gooseberries and currants, the sepals are united
to form a calyx tube, in the potato flower the petals are united
to form a corolla tube, in the cotton flower the stamen fila-
ments are joined, and in many instances — onion, apple,
orange, and others — the carpels are united. The adjectives
to describe these various cases are as follows:

FLOWERS 55

Separate United

Sepals aposepalous synsepalous

Petals apopetalous sympetalous

o^ , J 1 , f diadelphous (2 groups)

Stamens polydelphous { J 1 1. / \

^ -^ ^ [ 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 "f/fce-
cious." In some dioecious species (hops), the staminate
and pistillate inflorescences are very unlike in appearance,
while in other dioecious species (salt-grass, Distichlis), the
two unisexual inflorescences are very similar. If staminate
and pistillate inflorescences are on the same individual plant,
it is said to be "monoecious." This is the case in corn, in
which the "tassel" (staminate inflorescence) and the "ear"
(pistillate inflorescence) are very dissimilar in appearance.

Inflorescence.— An inflorescence is a flower cluster. Its
shape and the arrangement of the flowers in it differ with the
kind of plant. There are three general classes of inflores-

56 BOTANY OF CROP PLANTS

cences: (i) simple, (2) indeterminate or racemose, and (3)
determinate or cymose.

The simple type is well represented by the calla Hly 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.

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 micro pyle 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:

Seed

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.
57

58 BOTANY OF CROP PLANTS

Development of the Fruit. — The stimulus of fertilization,
which is not well understood, extends its influence not only
to the ovule, but to the ovary as well. Coincident with the
changes resulting in the mature seed, the ovary enlarges, and
its walls become changed both physically and chemically.
The ovary wall (pericarp) has three distinct layers. Named
in order from the outside to the inside, these are the exocarp,
mesocarp and endocarp. As the fruit develops the changes
that occur in these layers may differ. For example, in the
cherry or plum, the exocarp becomes the skin of the fruit,
the mesocarp becomes thick and juicy to form the fleshy
portion of the fruit, while the endocarp takes on a stony
character.

Fruit and Seed Distinguished. — A fruit, botanically, is
the matured ovary, with its seeds, and any parts of the flower
which may be closely associated with it. The fruit contains
the seed or seeds. For example, the entire bean pod is a
fruit; the "beans" within are the seeds. It is in the case of
dry, one-seeded fruits, particularly, that distinction needs to
be made between fruit and seed. For example, the buck-
wheat fruit (achene) or grass fruit (grain) is commonly called
a "seed." But, if development of these is traced and their
structure carefully examined, they are seen to be true fruits,
with a very thin pericarp (ovary wall) enclosing one seed
(Figs. 35 and 115).

Kinds of Fruits. — No attempt will be made at this place
to give a complete classification of fruits. We will describe
the different kinds as we meet with them in the discussions
of crop plants. Fruits with a dry pericarp, such as the grain,
achene, capsule and pod, are designated dry fruits. De-
hiscent dry fruits (capsule, pod, foUicle) 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

TRUITS, 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
foHage leaves.

As soon as the first roots are established, making it possible
for the plant to absorb water and mineral nutrients from the
soil, and a few leaves are formed, the young plant is capable
of making its own food and living an independent 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.

CHAPTER VIII
THE CLASSIFICATION AND NAMING OF PLANTS

That subject which deals with the arrangement of plants
into groups, based upon their structure and form, is desig-
nated Systematic Botany. From the earliest times, man has
attempted to classify the large and varied assemblage of
plants which he has found on the earth. There have been
many systems of classification, some "artificial," some
"natural." An artificial system of grouping plants may
use purely arbitrary bases; it may be convenient, but fail
to express the natural affinities of plants. For example, in
an artificial system, we might choose to put all those plants
with red flowers into one group, and those with blue flowers
into another class, and so on, thus basing our classification
on flower color. Or, we might put trees into one group,
shrubs into another, and herbs into still another, thus basing
the grouping on size and growth habit. Obviously, we
would throw together plants which have no natural relation-
ships, and in some cases, separate those which are naturally
allied. An artificial system would not take into account the
evolutionary tendencies in the plant world. It is agreed
that one system of classification is better than another if it
more accurately expresses the natural affinities and the
evolutionary tendencies of the organisms dealt with.

In the early history of systematic botany, the systems of

classification were largely artificial. As the knowledge of

plants increased, one system supplanted another, and in

most cases was an improvement over the old one. One of

THE CLASSIFICATION AND NAMING OF PLANTS 6 1

the first natural systems of classifying 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 Candolle (1819),
Eichler (1883), Bentham and Hooker (1826-1883), and Eng-
ler and Prantl (1890-1896). Two recent systems are those
of Bessey (1907), and of Schaffner (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 stability of the reproduc-
tive structures of a plant, these are of relatively great value
in showing actual relationships, and are of prime importance
in classification.

GROUPS OF PLANTS

A survey of the plant kingdom shows it to be composed of
a great variety of plants, differing in size, in structure, in
habitat, and in method of living.

62 BOTANY OF CROP PLANTS

The "thallus plants" (Thallophytes) include the simplest
organisms. This group is divided into two large subdivi-
sions, the AlgcB 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" (Pkridophytes) 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 Gymnospermce (pines,
spruces, firs, hemlocks, cedars, junipers and other cone-bear-
ing plants) and the AngiospermcR (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)
Monocotyledpnes, in which the seeds have one cotyledon', the
flower parts are in threes, the leaves are parallel-veined, and

THE CLASStPlCATlON AND NAMING OF PLANTS 6;^

the vascular bundles are scattered throughout the pith
(examples: cereals, onions, asparagus, lilies); (2) Dicotyle-
dones, in which the seeds have two cotyledons, the flower
parts are in fours or fives, the leaves are netted-veined, and
the vascular bundles are in the form of a cylinder about the
pith (examples: buckwheat, beet, apple, cherry, mustard,
cotton, melon, potato).

Each of these subclasses is further subdivided. A com-
plete classification of some plant, e.g., common alfalfa, will
give the principal subdivisions:
Spermatophyta,
Angiospermse,
Dicotyledones,
Order Rosales,

Family Leguminosae,
Genus Medicago,
Species Medicago sativa.
The order ending is usually "ales.'' Orders are subdivided
into families. The family ending is commonly "acecs" or
"cB." Families are spHt up into genera, and genera into
species. The number of families, genera, and species may
be large or small.

THE PLANT KINGDOM

Thallophytes— "Thallus plants."

Myxomycetes — slime molds or slime fungi.
Schizophytes — "splitting plants. "

Cyanophyceae — blue-green algae.

Schizomycetes — bacteria.
Algae — ^pond scums, sea weeds, etc.

Chlorophyceae — green algae.

Phaeophyceae — brown algae.

Rhodophyceae — red algae.

64 BOTANY OF CROP PLANTS

Fungi — molds, yeast, mildews, rusts, smuts, toadstools,
lichens, etc.

Phycomycetes — algal-like fungi.

Ascomycetes — sac fungi.

Basidiomycetes— basidium fungi.
Bryophytes — "moss plants."
Hepaticag — liverworts.
Musci — mosses.
Pteridophytes — "fern plants."

Lycopodiales — club mosses, lycopods, quillworts.

Psilotales — two small living genera.

Sphenophyllales—a single Carboniferous genus.

Equisetales — horsetails.

Ophioglossales — adder's tongue, moonwort.

Filicales — true ferns and water ferns.
Spermatophytes — "seed plants."

Gymnospermae— lower seed plants: cycads, ginkgo, coni-
fers, joint-firs, etc.
Angiospermae — higher seed plants.

Monocotyledones.

Dicotyledones.

PLANT NOMENCLATURE

Scientific Name.^ — The system of nomenclature in use by
all biologists today is the so-called binomial system. The
scientific name of each plant (and animal) is composed of
two words. For example, the scientific name of the common
garden bean is Phaseolus vulgaris L. The first word, Phase-
olus, is the name of the genus (pi. genera), or generic name;
the second, vulgaris, is the name of the species (pi. species) or
specific name. The letter "L" following the scientific name
of the common garden bean is the abbreviation for Linnaeus.
Placed in this position after the name of the plant, it signifies

THE CLASSIFICATION AND NAMING OF' PLANTS 6$

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-galli (L.) Beauv. This illustrates
a case in which a species has been transferred from one
genus to another. Linnaeus named the common barnyard
grass Panicum 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 Rubus
villosus (northern dewberry).

66 BOTANY OF CROP PLANTS

Descriptive Nature of Specific Names. — Specific names
are commonly descriptive. They may be descriptive of
(i) some plant character or habit, (2) habitat, or (3) dis-
tribution; and, in some instances (4) the species may bear
the name of an individual. By far the largest proportion
of specific names is descriptive of some striking habit or
character of the plant. For example, the trailing or pro-
cumbent Trifolium (clover) is Trifolium repens (repens,
creeping); the sweet clover with white flowers is Melilotus
alba (alba, white); the narrow-leafed crab-apple is Malus
angustifolia (angustus, narrow — folium, leaf).

In Vitis Hparia, the streamside grape, riparia is descrip-
tive of this species' habitat. The common black-cap rasp-
berry is Rubus occidentalis; here the specific name means
"western." Again, in Vaccinium canadense, the Canada
blueberry, the specific name indicates geographical distribu-
tion. The systematist frequently uses the name of an indi-
vidual for the specific name. This may be done as a token
of friendship, or recognition of distinction, or to indicate the
finder of the new form. For example, Prunus besseyi, is
after the well-known botanist, Charles Bessey. The i
ending is the Latin genitive, signifying "of Bessey."

Scientific Name versus Common Name. — There are dis-
tinct advantages connected with the knowledge and use of
scientific names. Often the same species has many common
names. Again, several distinct species often may go by the
same common name. The use of one scientific name will do
away with much misunderstanding as to what plant is
actually referred to.

General References

Bailey, L. H.: The Standard Cyclopedia of Horticulture. The Macmillan

Co., 1914.
Baillon, H,: Histoire des plantes. Paris, 1894.

THE CLASSIFICATION AND NAMING OF PLANTS 67

Bentham, G., and Hooker, J. D.: Genera Plantarum. London, 1862-1883.
Brixton 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., 1911.
De Candolle, Alphonse: The Origin of Cultivated Plants. D. Appleton

& Co., 1892.
Engler and Prantl: Die naturlichen Pflanzenfamilien.
HtJNT, 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.
Perclval, 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.
WossiDLO, Paul.! Leitfaden der Botanik. Berlin, 1911.

PART II

CHAPTER IX
GRAMINE^ (POACE^), GRASS FAMILY

No family of plants is of greater economic importance than
the grass family. It has several thousand species, among
which are the "grains" (such as wheat, oats, barley, corn,
rice, and others) and the meadow, pasture and range grasses.
The grasses grown for "grain" were the first plants to be
cultivated by the human race. Members of this family
are widely distributed over the surface of the earth, from
tropical to polar regions and from low to very high altitudes.
In many parts of the world, grasses form a dominant part
of the plant covering. Examples of extensive grass associa-
tions are meadows, steppes, and savannahs. Meadows are
moist grass lands and may occur in all climates. Steppes are
dry grass lands. The Old World steppes of Russia, Hungary,
Roumania, and Spain, the plains of the Western United
States, and the pampas of South America are excellent
examples. Savannahs are dry grass lands with scattered
trees. The best examples of these are the llanos of Venezuela,
and the patanas of Ceylon.

Habit of Plants.— Most grasses are low, erect herbs. A
few, such as the bamboos, are shrubs or trees. Bamboo
has a woody stem which may reach a height of loo feet or
more. Some grasses are trailing, one or more being re-
ported as climbing over trees loo'^feet high. Others, like
69

70 BOTANY OF CROP PLANTS

rice cut grass (Homalocenchrus) are feeble climbers or support
themselves by means of numerous hooked prickles on their
leaves.

Many of our common pasture and meadow grasses, and
all the cereals, complete their life period in one season. Such
plants are said to be annual. In cool climates, certain
grasses behave as winter annuals, living through the winter
as small plants and sending up jQower 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 re pens), 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 33^ feet (Fig.
56), emmer and spelt 3}^ feet, and wheat more than 4 feet.

Roots may break through the sheaths (that part of the

GRAMINE^ (pOACE^e), GRASS FAMILY 7 1

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

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
{internodes) (Fig. 25) which
are usually hollow, but some-
times filled with pith, as in
corn. When young, the in-
ternodes are soKd, 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 youngest
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 juncture of leaf and blade;
B, stem cut in median lengthwise
section. X 2}i.

GRAMINE^ (pOACEiE), GRASS FAMILY 73

when its stems are bent over and caused to lie on the ground
by the mechanical action of a high wind, or driving rain.
Some grasses lodge more easily than others. This may be
due either to their greater height, heavier fruiting head, or
to a lack of strengthening material. Moreover, it has been
shown that an excessive amount of available nitrates in the
soil favors lodging. As it has been demonstrated that the
application of nitrate fertilizers to a soil tends to suppress
the amount of silicon taken in by the wheat plant, the greater
frequency of lodging of plants grown on such a soil may re-
sult from a stem weakness caused by a lack of silicon within
them. However, the causes of lodging are not well known.

The stems of lodged grain are not necessarily broken.
The reverse is the case, as is shown by the fact that the lodged
culm has the power of partially or entirely erecting itself.
This power is exhibited more strongly in growing or imma-
ture culms than in old ones. When a grass stem is lodged,
the cells on the lower side of each internode, at its base,
grow more rapidly 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' '

BOTANY or CROP PLANTS

(Fig. 27), and the entire mass of branches is the "siv/ol."
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
6cale leaf
'^^^econdary stem
^ priivar\j stem

^^-^crown roots

-^rain remains
J^^nmar\j roots

-Diagrammatic representation of tillering in cereals.
{After Schindler.)

appear to come out at one point. In the wheat plant, two
or three weeks old, three or four buds may be found, one in
the axil of each leaf. Tillering results from the outgrowth
of these lateral buds.

Tillering activity varies with the species, the individual,
and environmental conditions. In- general, winter grains
tiller more than summer ones. It is dependent especially
upon the depth of seeding. There seems to be an optimum
depth, which varies with the sort of grass. The average
depth of the tillering node in cereals is about i to 2 centi-

GRAMINE^ (POACE^), GRASS FAMILY

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

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 internodes are enlarged into bulb-
like bodies containing a store of nourishment.

Rhizome-bearing Grasses. — Perennial grasses usually
have rhizomes or rootstocks, horizontally elongated under-
ground stems, which give rise to erect annual stems that
bear foliage leaves and flowers. These underground stems
are very efficient as reproductive organs, for, as a result of
their elongation in the soil, the plant is able to invade areas
already occupied by other plants. Furthermore, each root-
stock is capable of budding a new plant at every node, and
should it be dragged from the ground by cultivating machin-
ery and broken into a number of separate pieces, each piece
will give rise, under favorable conditions, to a new^plant.
Quack grass (Agropyron repens), and many other of our

76 BOTANY OF CROP PLANTS

worst weeds, owe their obnoxious character mainly to the
possession of rootstocks. Such plants are not dependent
upon seed production alone, but in addition spread by means
of their rootstocks. The rootstock is a storehouse of food
material, and although the leaves and stems above ground
may be destroyed, new shoots are sent up from it, drawing
upon the stored food supply. For this reason, perennial
weeds of all kinds are difficult to eradicate. Any method of
elimination adopted is based upon the knowledge that the
food stored in the underground stems is made in the green
leaves; therefore, the development of green leaves must not
be allowed.

Rhizomes of grasses bear brown or colorless sheathing
scales (rudimentary leaves) containing in their axils active
buds which may develop into erect stems. Under favorable
conditions, roots are produced at the nodes of the rhizomes.
Grasses possessing rhizonies 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

GRAMINE^ (POACE^), GRASS FAMILY 77

sod that would be as enduring under conditions affecting the
sod surface, such as heavy trampling or close grazing.

Leaves. — General Characteristics. — In grasses, a single leaf
arises at each node. Leaves disposed in this fashion along a
stem are said to be alternate. If one starts with a certain
leaf, the leaf next above or next below, is on the opposite side
of the stem, i8o° around the circumference. This arrange-
ment gives two vertical rows of leaves opposite each other
on the stem. Such an arrangement is said to be two-ranked,
distichous, or one-half spiral. We shall have occasion further
on to discuss other leaf arrangements, and to emphasize
the fact that leaves are developed on a stem in a definite
order.

The grass leaf in general appearance is unlike that of such
common plants as apple, cottonwood, maple and beet. In
these the leaf has a definite, narrow stalk or petiole and an
expanded blade (Fig. 159). The grass leaf is divided into
two distinct parts, sheath and hlade (Fig. 26). The sheath
represents the leaf base, and forms a tube around the culm.
At the base of the leaf sheath, there is a distinct swelling.
The more or less flattened part of the leaf which spreads
away from the culm is the hlade (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).

yg BOTANY OF CROP PLANTS

The upper portion of the leaf may therefore be removed
without permanent injury to the plant. This is well shown
in the rapid recovery of the leaves of lawn grass after mowing,
and of pasture grasses after grazing.

Scales and Bracts. — Reduced leaves in the form of scales
and bracts occur in grasses. Such reduced leaves are termed
''scales" when they appear lower on the stem than the
foliage leaves, and "bracts" when higher. For example,
the reduced leaves at tillering nodes are "scales" (Fig.
27), while the reduced leaves (glumes) in the inflorescence
are "bracts" (Fig. 28). Scales and bracts seldom possess
chlorophyll (green coloring material in plants), and, hence,
are incapable of carrying on synthesis of carbohydrates.
The scales and bracts in grasses have the same one-half
spiral arrangement as the foliage leaves and although they
may be very close together on the axis, careful observation
shows them to have this typical arrangement of all grass
leaves.

Ligule. — At the junction of the sheath and blade is a
membranous or cartilaginous ring or fringe, the ligule (Fig.
26). It is next to the culm, and varies in size, shape, and
hairiness in different species of grasses. The ligule is
sometimes absent.

Auricle (Fig. 26). — This is a more or less pointed, thin,
ear-like structure projecting from the leaf edge at the junc-
tion of sheath and blade. It often clasps the stem but
may be more or less twisted and bent away from it. It
varies greatly in size and shape. In the tribe 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 spikelet. The spikelet is, in fact, the unit of the

GRAMINE^ (POACE^), GRASS FAMILY

lemmas

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 unbrahched,
so that the spikelets are not borne on individual stalks, but
are attached directly (sessile) to the rachis, the result is a
spike. The inflorescences of wheat,
barley, and rye are good examples of
spikes. Usually, each culm bears a
single spike. In the raceme, each spike-
let is borne on a short branch of the
rachis, as in sheep's fescue {Festuca
ovina). In the panicle, the primary
branches of the rachis branch one or
more times (Fig. 44). These branches
may be long and widely spreading, as
in oats and brome grass, or short and
rather appressed to the rachis, as in
timothy, meadow foxtail {Alopecurus) ,
and Koeleria.

Different types of inflorescences be-
sides the spike, raceme and panicle will
be met with in some of the following
families. We shall also see that these
three types are not confined to the grass family, but are in
fact exceedingly common among seed plants of all kinds.

Spikelet. — The spikelet is the unit of inflorescence in
grasses. A typical spikelet, such as that of oats (Fig. 46),
or wheat (Fig. 28), for example, consists of a shortened axis,
the rachilla, bearing a number of chaff-like, two-ranked
(distichous), overlapping bracts (glumes of some authors).
The two lowermost bracts are empty, that is, do not bear
flowers in their axils. Fig. 29 shows a dissected wheat

rachis

Fig. 28. — Single spike-
let of common wheat
(Triticumaestiviim). X 2.

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 glunies, 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,

Iji glume

Fig. 29. — Spikelet of common wheat (Triticum sestivum) dissected, the parts
removed in order.

bracteole, and superior palea of some authors) . Its back is
turned toward the rachilla. It frequently envelops the
other parts of the flower with its infolded edges. The palet
is never awned (bearded). While the glumes and lemmas
are inserted on the rachilla, the palet is inserted on a very
short flower stalk (pedicel) . At the base of the ovary, on the
side opposite the palet, are two minute scales, the (anterior)
lodicules (Fig. 30). Inside the palet, and placed farther up
on the flower stalk, are three stamens and a single pistil.
Thus we see that in the typical spikelet there are two glumes

GRAMINE^ (POACE^), GRASS FAMILY

subtending one or more lemmas; in the axil of each lemma is
a flower, and each flower consists of a palet (outer perianth),
two lodicules (inner perianth), three stamens, and a single
pistil. Each stamen has a large anther. The filament
{stalk) is attached at the base of the anther, but on account

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-
Ihus, the empty glumes are absent; in Nardus, solitary; in Bomalocenchrus,
mere rudiments. In some Agrostis species, the palet is rudimentary. It is
not always two-keeled, but generally two-nerved. There is a third (posterior)
lodicule in some grasses. Although the stamens are as a rule three, there are
six in most bamboos and in rice {Oryza). In Streptochceta and Oryza (oc-
casionally), there are three styles, and only one in Nardus.
6

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 cleistogamous
grasses. As compared with flowers that open, cleistogam-
ous ones generally have reduced lodicules, smaller anthers,
a shorter pistil, and less pollen. In a few cases {Panicum
clandestinum) for example, -claasmogamous spikelets and
cleistogamous spikelets may occur in the same inflorescence.
According to Koernicke, two-rowed erect-eared barley
{Hordeum distichon erectum) bears only cleistogamous
flowers.

Pollination. — Wind is the chief agent in the dissemination
of grass pollen. In all grasses the pollen is light and dry, and
hence easily blown. Insects play a very unimportant part
in this process.

Most grass flowers open to shed their pollen, that is show
chasmogamy. In some grasses, however, the glumes do not
spread apart, thus allowing the stamens and pistils to be-
come exposed. Flowers that do not open are said to show
deistogamy.

Fruit. — In all grasses, the fruit is one-seeded, dry, and does
not spUt open at maturity to allow the seed to escape. The
pericarp (ovary wall) is firmly attached to the seed coat.

GRAMINE^ (pOACEiE), GRASS FAMILY

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 Hly-Hke
plants by a reduction and modification
of a number of part's 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 Hhes; there was a reduction in the lobes of

Fig. 31. — Diagram of
A lily flower, and B
grass flower showing
homologous structures.
A, f, bract; ax, axis;
op, outer perianth; ip,
inner perianth; s, sta-
mens; c, tricarpellary
ovary. B, shaded struc-
tures are aborted; le,
lemma (bract) ; ax, axis;
p and p', palet (outer
perianth); I and I',
lodicules (inner peri-
anth); 5 and s', two
whorls of stamens; c,
tricarpellary ovary. {B
after Schuster.)

84 BOTANY OF CROP PLANTS

the pistil from three to one, a loss of one whorl of stamens,
and a reduction in the number of perianth lobes.

Although commonly assumed to be one-carpelled, the
grass pistil is really tri-carpellary. This latter view is
held by a number of morphologists (Doell and Goebel),
and recently has been quite conclusively demonstrated
by Walker and Schuster. In all grasses, the pistil has
three fibro-vascular bundles. Two of these extend to the
style branches and the third (dorsal) extends to the
dorsal lobe of the pistil or to the third rudimentary style
branch, when present. This third bundle bears the ovule.
In Streptochceta and Bambusce, there are three styles.
Furthermore, it should be noted that the three vascular
bundles stand in regular alternation with the second whorl of
stamens and the inner whorl of the perianth.

Rowlee, in a study of Arundinaria, a bamboo, concluded
that the lodicules represent the inner perianth whorl. The
common view, as presented by Hackel, has been that lodi-
cules are bracts. Schuster's researches substantiate those
of Rowlee. He finds that, although two lodicules is the com-
mon number, a third (anterior) one occasionally occurs (in
Bambusae) ; that the two (posterior) lodicules are not bound
together at first but originate separately; that in one grass
genus {Streptochaeta) , at least, the three lodicules are inde-
pendent. From these studies, it appears that the lodicules,
morphologically, are to be considered as the inner perianth
whorl. The same worker (Schuster) considers the palet to
represent the outer perianth whorl of this lily-like flower.
The palet is usually two-keeled or two-nerved. There are
cases in which the palet is divided into two parts, and in
which there is a third part in a rudimentary condition. In
the majority of grasses, the two parts of the palet arise from
separate primordia, later growing together to form a single

GRAMINE^ (POACE^), GRASS FAMILY 85

structure; the third, outer perianth whorl aborts. In this
connection it should be noted that the palet of einkorn
(Triiicum monococcum) divides into two parts, at maturity,
on the median liiie, 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 {CyperacecB). 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 spht (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
{JuncacecB}, other than rush-like sedges, which are grass-
like in appearance. These, however, are distinguished from
the grasses by the presence of a perianth of six distinct glume-
like segments.

86 BOTANY OF CROP PLANTS

References

Baillon, H.; L' evolution de Tinflorescence dans les Graminees. Bui.

Soc. Linn. Nord, France, 1894, 1123-1128.
Bruns, E.: Der Grasembryo. Flora, 76: 1-33, 1892.
Chase, Agnes: Notes on the Cleistogamy of Grasses. Bot. Gaz., 45: 135-

136, 1908.
DoELL.: Untersuchungen iiber den Bau der Grasblute. Jahresber. Mann,

Ver. f. Naturk., 1868, xxxiv and 1870, xxxvi.
GoEBEL, K.: Ein Beitrag zur Morphologie der Graser. Flora, 1895,

Erganzungsband.
GuERiN, P.: Recherches sur le development du tegument seminal et du

pericarpe des graminees. Ann. Sci. Nat. Bot., 9: 1-59, 1899.
Hackel, E.: tJber das Aufbluhen der Graser. Bot. Ztg., 33: 432, 1880.

Untersuchungen iiber die Lodiculas 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.

Uber Kleistogamie bei den Grasern. Osterr. Bot. Ztschr., 55: 81-88,

143-154, 180-186, 1906.
Hitchcock, A. S. : A Text-book of Grasses with Especial Reference to the

Economic Species of the Unites States. The Macmillan Co., New York,

1914.
JUMELLE, Henri. : Note sur la constitution du fruit des Graminees. Compt.

Rend. Acad. Sci. (Paris), 107: 285, 1888.
Kennedy, P. B.: The Structure of the Caryopsis of Grasses with Reference

to Their Morphology and Classification. U.S. Dept. Agr., Div. Agros.,

Bui. 19, 1900.
Lamb, William H.: The Phylogeny of Grasses. Plant World, 15: 264-270,

1912.
Piper, C: The Terminology of the Parts of the Grass Spikelet. Science,

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

Bot. Gaz., 25: 199-203, 1898.
Schuster, Julius: tJber die Morphologie der Grasbliite. Flora, 100: 213-

266, 1910.
Walker, E. R..: On the Structure of the Pistils of Some Grasses. Thesis,

Univ. Nebr., 1906.
Ward, H. Marshall: Grasses, a Handbook for Use in the Field and

Laboratory. Cambridge, 1901.
True, Rodney: On the Development of the Caryopsis. Bot. Gaz., 18:

212-226, 1893 (contains bibliography on development of grain).

GRAMINE^ (POACE^), GRASS FAMILY 87
CEREALS

Cereals are those grasses which are grown for their grain.
Buckwheat is sometimes considered a cereal because its
fruit (achene) is ground into flour, but it is not so considered
here.

Buckwheat, flax, and others, which are often raised for
their seed or fruit, but are not grasses, are discussed wherever
they happen to come in the botanical order of treatment
followed here.

Key to Groups (Genera) of Important Cereals^ .

1 Whai is a "key," and how is it used? Throughout the following pages
there will be a number of "keys." A "key" is a convenient form for dis-
tinguishing one plant from another, or one plant group from another. It
presents in concise form the principal differences between the plants con-
sidered. It also enables one to determine the proper classification of an
unknown plant. Most of the "keys" in the following pages are "artificial,"
that is, the characters used are obvious ones. The "keys" herein are con-
structed on the dichotomous plan, i.e. by twos. The entire number of groups
under consideration, whether these be species, genera, families, or higher
divisions, is first divided into two subgroups; each of the subgroups is sub-
divided into two groups, and so on. The alternatives are equally indented
on the page. In the key to the genera of cereals, they are first divided into
two large groups, the first including Zea, Oryza, Andropogon and Millets;
and the second, Avena, Secale, Triticum and Hordeum. It is seen that those
genera of the first group have "spikelets falling from the inflorescence entire
..." while those of the second group have "spikelets falling from the in-
florescence without the glumes. . . " Each of the two large groups
is again separated into two subdivisions. For example, the genera Avena,
Secale, Triticum and Hordeum, are subdivided on the basis of their inflores-
cences. Avena has a panicle inflorescence, while Secale, Triticum, and Hor-
deum have a spike inflorescence.

Let us suppose that we have a cereal in hand, the genus of which we wish
to determine. First of all, it would be necessary to decide whether the
"spikelets fall from the inflorescences entire . . . ;" or "spikelets fall
from the inflorescence without the glumes . . . ;" if it has the characters
of the second alternative, we know it is either oats, rye, wheat or barley.
Should the specimen in hand have a spike inflorescence, oats is eliminated
from consideration, and the plant must be either rye, wheat or barley. If,

88 BOTANY OF CROP PLANTS

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

The "key" shows many of the characteristics of a group. Consider
Triticum (wheat), for example. One can see by the key that "spikelets fall
from the inflorescence without the glumes, which remain attached to the
rachilla; spikelets one-many- flowered; rachilla often produced beyond the
upper glume; grain with a longitudinal furrow; tuft of hairs at tip of ovary."
Furthermore, that the "inflorescence is a spike"; that there is "one spikelet
at each joint of the rachis," and the "glumes are not bristle-like, but broad,"

Spikelets falling from the inflorescence entire (glumes attached to grain), one-
flowered, or if two-flowered the lower one staminate; rachilla not pro-
duced beyond the flowers; grain without a longitudinal furrow; no tuft
of hairs at tip of ovary.
Flowers staminate and pistillate; borne in separate inflorescences on the

same plant, i.e., monoecious (Fig. 57), Zea (maize or Indian corn).
Flowers perfect or staminate; when the staminate are present, borne in
same inflorescence with perfect.
Spikelets much compressed laterally (Fig. 75), Oryza (rice).
Spikelets cylindrical or somewhat compressed dorsally.
Lemma and palet thin and papery, much more delicate in texture than
the empty glumes (Fig. 71), Andropogon (sorghum, milo, broom
corn, etc.)
Lemma and palet, at least of perfect flower, never thin and papery,
parchment-like or leathery, hard and shiny, very different in color
and appearance from the glumes (Fig. 83), 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), Avena (oats).
Inflorescence a spike.
One spikelet at each joint of rachis.

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

■ Key to Small-grain Seedlings^

iThis 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.

GRAMINE^ (pOACEiE), GRASS FAMILY 89

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

cum dicoccum) .
Sheaths and blades not pubescent.

Collar and claws large, Spelt {TrUicunt spelta).
Collar and claws slender. Wheat {Triticum astivum).
Claws not hairy.
Collar and claws large and prominent.
Nerves of blades not prominent, upper surface rough, Barley {Uor-

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

References

Aaronsohn, a.: tJber die in Palastina und Syrien wildwachsend aufgefun-
denen Getreide-arten. Verhandl. K. K. Zool. Bot. Gesell. Wien.,

59:385-590, 1909-
Contribution i I'histoire des cereales. Bui. Soc. Bot. (France), 1909.

Attekberg, 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, 1917.

Deherain und Dupont: tJber den Ursprung der Starke im Getreidekorn.
Comp. Rend. Acad. Sci. (Paris), 133:774, 1902.

Desriot, a.: Les cereales, 2 ed., Paris, 1910, Hachette et cie.

Ekkert, F.: tJber Keimung, Bestockung und Bewurzelung der Getreide-
arten. Inaug. Diss. Leipzig, 1873.

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

Fruwirth, W.: Die Ziichtung der landwirtschaftlichen Kulturpflanzen.
Berlin, 1910.

KoERNiCKE, F. and Werner, H.: Handbuch des Getreidesbaues. I. Die
Arten und Varietaten des Getreides. II. Die Sorten und der Anbau
des Getreides. Berlin, 1885.
tJber die Entstehung und das Verhalten neuer Getreidevarietaten.
Archivs fiir Biontologie, 1908.

90 BOTAN"i^ OF CROP PLANTS

Kraus, C: Die Lagerung der Getreide. Stuttgart, 1908.

Knissling, L.: Untersuchungen iiber die Keimung der Getreide. Landw.

Jahrb. (Bayern), 1:449-514, 191 1.
KuDELKA, F.: Uber 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, 19 10.
Hoffman: Das Getreidekorn. Berlin, 191 2.

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

the old literature on the blooming of grasses).
Untersuchungen iiber die Bestockungen des Getreides. Jahrb. Deut.

Landw. Gesell., 1903.
ScHiNDLER, Franz: Der Getreidebau. Berlin, 1909.
ScHMiD, B.: Bau und Funktionen der Grannen unserer Getreide-arten. Bot.

Centralbl., 76, 1898.
Schmidt, O.: Uber den Entwicklungverlauf beim Getreide. Ein Beitrag

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

friichte in verschiedenen Stadien der Entwickelung. Berlin, 1911.
Seelhorst, v.: Versuche iiber die Moglichkeit einer Bewurzelung und

Adventivtriebbildung an oberirdischen Knoten von Getreidepflanzen.

Jour. Landw., 1902.

CHAPTER X
TRITICUM (Wheat)

Habit of Plant. — Wheat is an annual. Under our cultural
conditions, there are two seasonal forms, winter annual, or
winter wheat, and summer annual, or spring wheat.

Roots. — Wheat has a fibrous root system. ■ In the germina-
tion of the grain, the primary root (Fig. 2) takes the lead;
very soon, two secondary roots appear on either side of the
primary, thus forming a whorl of three. Later, other roots
may be added to these. This whorl constitutes the primary
or temporary root system. It usually dies before the plant
is fully grown. Permanent roots appear in whorls at the
nodes some distance above the three temporary roots. The
first whorl of permanent roots is generally about i inch below
the soil surface, no matter at what depth the grain was
planted (Fig. 3). In their growth, the whorls of permanent
roots curve outward and then downward, taking an almost
vertical course. They branch very freely near the soil sur-
face and form within the first foot a fine network, which
constitutes a large absorbing surface. However, many of
the roots of wheat reach a depth of 4 feet, or even more under
favorable soil conditions. Nobbe observed that the aggre-
gate length of all the roots of a one-year-old wheat plant
amounts to 500 to 600 meters. The number of roots increases
with the number of tillers.

Stems. — The stems of wheat are of the general grass type.
In wheat, there are usually six joints (internodes), the sixth
being the spike-bearing one. The lowest joint usually re-
91

92 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 spUt; the ligule is
thin and transparent; the auricles are conspicuous, although
not as prominent as those in barley.

Inflorescence. — Wheat flowers are arranged in spikelets
and the spikelets into a ''head" or spike (Fig. 38). The
spike varies in size, compactness and form in the different
types of wheat. Fifteen to twenty fertile spikelets in a head
is a fair average, but spikes have been observed with a
number considerably greater. An abundance of water in
the soil during the early stages of development has been found
to increase the number of spikelets in a head. The racUs
or main axis of the spikelet is zigzag in shape (Fig. 48).
Each joint of the rachis is flattened and curved, the concave
surface being on the side next to the spikelet. There is but
one spikelet at each joint of the rachis. There are usually
numerous short so-called "basal hairs" at the base of each
spikelet. The lower spikelets of the head are often sterile;
less frequently, the terminal spikelet is sterile (as in einkorn).

Spikelet. — The number of flowers in a wheat spikelet
varies from two to five. It has been shown that the number
of flowers that reach maturity in a spikelet may be increased
by an ample supply of water during the period when the
flowers are developing. It is quite probable that there is
a "critical period" in the life of the plant at which time the
supply of moisture coming to the plant has the maximum
effect in the production of flowers. This critical period is
probably during the early stages of flower formation, quite
a while before the time of heading.

The wheat spikelet dissected in Fig. 29 has four flowers,
three of which have matured grain. The fourth flower is

TRITICUM

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.

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

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 usually in several days.

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

TRITICUM 95

gamy) is the rule in nearly all wheats. Durum wheat, how-
ever, has the habit of cross-pollination (xenogamy), and it has
been suggested that this behavior is partly responsible for
its better adaptation to dry climates, and for its greater dis-
ease resistance and vigor. Cross-pollination is quite common
in the primitive wheat, which is an inhabitant of a dry, warm
country. It appears that cross-pollination is the rule in
hot, dry localities, such as certain parts of India.

Artificial Cross-pollination. — One of the chief means of
wheat improvement is hybridization. This necessitates the
operation of artificial cross-pollination. In this process,
the glumes of the flower of the female parent are spread
apart and the three stamens removed; this is done just before
the anthers are mature. On the same day, or on the follow-
ing morning, pollen is taken from the mature anthers of the
plant to serve as the male parent, and placed between the
glumes of the flower from which the stamens have been re-
moved. The chances are that the pollen will reach the
stigma branches of the emasculated flower, germinate, and
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.

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. 2>3)- 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
V about four weeks after pollination.

About a week later, two other rootlets

(appear above the first pair, and
Brenchley describes a fifth lateral
rootlet, which does not appear until
quite late.
Endosperm. — In about a week or ten
days after fertiUzation, a definite tissue
is formed within the embryo sac. This
is the endosperm. About seven or
eight days later, the aleurone layer is
marked off, appearing first on the dorsal
side. According to Brenchley, starch
first begins to appear in the "flank"
cells about the eleventh day after pollination. Eckerson
points out that the actual time of the beginning of deposi-
tion depends upon the relative activity of the leaves in
making sugar and of the embryo in assimilating it.
Infiltration of starch is complete in about five weeks
after 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 :

ovm

Fig. 33. — Diagram-
matic section of young
ovary of wheat. {After
Bessey.)

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.
7

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:

Water content
of grain

Volume of loo
grains, cm*.

Dry substance

in 100 grains,

grams

Milk-ripe (o) July 9
Milk-ripe (6) July 13,

Yellow-ripe July 20

Full-ripe July 23

51-47
47.69
34-37
25-73
12.91
12.97

S-31
5-17
5-07
4.28
3-o8
3-52

2.86
3.58
4-44
4.19
3.80
4.22

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

TRITICUM 99

yielded 25 bushels per acre; in the full-ripe stage, 30 bushels
per acre, and in the dead-ripe, 28 bushels. The dead-ripe
stage produced the most vigorous seed, as was determined by
the length to which the plumule would grow. For example,
in the above experiment wheat collected in the dough stage
produced a plumule g^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 insufficient positive results to warrant the
belief that large plump seeds will give uniformly greater
yields than small seeds, especially when such seeds are secured
by means of the ordinary fanning mill. It is known that not
all the grains in a spikelet are the same size and weight —
the second is the heaviest, the first and third about equal in
weight, and the fourth and fifth, if present, are lightest of
all. It is obvious that all grains from a spikelet regardless
of their size, have the same heredity. And a light seed from
a spikelet usually will, under similar 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

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 asstivum). A, grain, groove side; B,
grain, embryo side; C, cross-section of grain through the embryo; D, cross-
section of grain beyond the embryo.

. starchu

'jper

endosterm

Fig. 35. — Microscopic section of wheat grain.

section of a mature grain of wheat through the embryo
region. The three primary roots are seen in section.

In a cross-section of a mature wheat grain, cut at right
angles to its length, so as not to include the embryo, the
following layers may be recognized (Fig. 35) :

TRITICUM lOI

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

2. Testa, two layers of inner integument.

3. Nucellus.

4. Aleur'one 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 einkorn have the palet and
lemma attached, and in these the pericarp is more weakly
developed than in the types of wheat with naked grains. In
all wheats, the layers of the grain, both fruit and seed, are
much thinner at the embryo end than in the other parts of
the fruit. It is known that the greatest amount of absorp-
tion of water takes place at the embryo end.

Testa (episperm). — It has been noted that, in the develop-
ing wheat grain, the testa is composed of two integuments of
two layers each. In the ripening process, the outer integu-
ment is entirely absorbed, so that in the mature grain the
testa consists of two rows of cells, belonging to the inner
integument. The walls are slightly 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

I02 BOTANY OF CROP PLANTS

yellow. The proportions of these colors determine whether
the wheat is white, yellow, or red.

Brown found in Triticum, as well as in Avena, Secale, and
Hordeum, that the semi-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 undeveloped ovule. The mature nucellus consists of
cells with strongly thickened walls, and with indistinct
cavities. It is possible that in some cases the nucellus is
completely absorbed, and hence wanting in the mature
grain.

Endosperm. — The endosperm consists of two portions,
starchy or floury endosperm, and aleurone layer. The endo-
sperm constitutes about 92 per cent, of the grain's volume.
The cereals are cultivated chiefly for the food material
stored in the grain. In all of them, the bulk of this food is
found in the endosperm. The chief food materials stored in
the endosperm of grains are starch and proteins. The
germinating embryo makes use of these foods in the first
few days of its growth, or until its roots are taking substances
from the soil, and the young leaves are manufacturing food,
or, in other words, until the young plant has 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

TRITICUM

103

SO the principal protein found in the starchy endosperm, and
thould not be used in connection with the aleurone layer.

Starchy Endosperm. — This is made up of large, somewhat
elongated, thin-walled cells. The longer axes of the cells
are usually at right angles to the grain surface. They are
filled for the most part with starch grains. Protein granules
may be seen among the starch grains by appropriate stain-
ing. Most, if not all, of the wheat starch and all of the

jfarchy
akurom-

jcuiellum-
coleoptih

h\ipoco\\jl —
em\a5i — -
' rooi

groove

cylmclric
ebiflidium

mscufar
bundte of

growing
U3t stem

coleorhiza^

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 amount.
Embryo. — ^A median lengthwise section of the grain of
wheat shows well the structure of the 'embryo (Fig. 36).
The seminal roots point toward the micropylar end. They
consist of a primary rootlet with two pairs of laterals.
According to Brenchley, a fifth lateral rootlet is formed in
addition to the two pairs usually described. These rootlets
are surrounded by the root sheath or coleorhiza. A very short

I04 BOTANY OF CROP PLANTS

stem, the hypocotyl, is between the primary root and the
growing point. In other words, the embryonic stem, or
hypocotyl, terminates at the anterior end in a growing point
and at the posterior end it is prolonged into the primary root.
There are several immature foliage leaves surrounding the
growing point and attached to the upper end of the hypo-
cotyl. The growing point and foliage leaves are surrounded
by a leaf sheath, the coleoptile or pileole. At the point where
the root sheath merges into hypocotyledonary tissue, there
is a small projection, the epihlast. Lying next to the endo-
sperm is a speciahzed structure, the scutellum, which is
attached to the hypocotyl. It has been suggested that the
scutellum and epiblast represent two cotyledons, one of
which (scutellum) is highly modified, the other (epiblast)
suppressed.

We are all familiar with the seedlings of bean or squash.
In these, there are two cotyledons (seed leaves) which
are brought above ground and function for a while as
green leaves. Plants with two cotyledons are said to be
dicotyledonous. The scutellum of grasses is regarded as a
cotyledon, morphologically. Plants Hke grasses, sedges,
rushes, liUes, etc., which have one cotyledon are said to be
monocotyledonous. If the epiblast represents a rudimentary
second cotyledon, as its position on the embryo would seem
to indicate, it stands as evidence of the fact that monocoty-
ledonous plants had dicotyledonous ancestry. Rudimentary
structures are a great aid in tracing the racial history of all
organisms.

The scutellum remains in the seed during germination,
serving in the absorption of and transfer of food from the
endosperm to the growing regions. The outermost layer
of the scutellum, where it adjoins the endosperm, is a
columnar epithelium. It is probably this layer which secretes

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

Io6 BOTANY OF CROP PLANTS

glutenin. The latter two proteins compose gluten. Gliadin
is the sticky substance in gluten.

As a general rule, grains that have a marked glutenous or
horny or flinty appearance are higher in protein than those
that have a starchy or dull appearance. However, it is
known that a given variety may produce a grain that is hard
and rich in gluten; or one that is soft and low in gluten, de-
pending on the environmental factors. But it seems true,
nevertheless, that the term "quality" refers to both the
physical characteristics and chemical composition of the
grain.

Relative Proportions of the Parts of the Grain. —

1. Bran (pericarp, testa, nucellus), 8 to 9 per cent.

2. Aleurone layer, 3 to 4 per cent.

3. Starchy or floury endosperm, 82 to 86 per cent.

4. Embryo or germ, about 6 per cent.

"Hard" and "Soft" Wheats.— A "hard" wheat is one with
a horny or flinty texture, and quite high in protein. Hard
wheats, as a result of their high gluten content, make a
"strong" flour, which is adapted for making Ught 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 difliculties in milling and baking.
In recent years, however, this opposition has been largely
overcome.

There are three classes of hard wheats in this country:
(i) hard spring wheat, (2) hard winter wheat, and (3)
durum wheat. The principal hard spring wheats are Fife

TRITICUM 107

and Bluestem. Turkey and Kharkov are the chief hard
winter wheats, and Kubanka the most important durum
wheat. On account of its highly glutenous character, durum
is used extensively in the manufacture of macaroni and
vermicelli. The flour of this hard, glutenous wheat is being
mixed with that from the softer wheats, and the result is a
flour of excellent bread-making qualities.

Much emphasis has been placed upon the great influence
of climate upon the composition, hardness and quality of
wheat. In fact, it is claimed, that the soil has Httle or no
effect upon these characters. In general, a hot, dry climate
produces a fine-stemmed plant the grain of which is hard,
glassy and rich in nitrogen, while a cool, moist climate pro-
duces a coarser-stemmed plant the grain of which is relatively
soft, mealy and poor in nitrogen. Headden, however, has
been able to produce starchy and flinty kernels at will in the
same variety growing under identical climatic conditions, by
controlling the ratio of nitrogen to potassium. An abund-
ance of nitrates produced a flinty grain, while a scarcity of
nitrates in proportion to potash gave a starchy, mealy
grain. This work establishes the fact that the soil, as well
as the climate, is a factor in determining the quality of
wheat.

Milling of Wheat. — The wheat is first thoroughly cleaned
and scoured to remove sticks, straw, fine dust particles, and
hairs of the brush. It is then slightly moistened with water,
in order to prevent the pericarp from grinding up fine. This
is known as tempering. Then comes the process of breaking.
This consists in removing the bran coats and embryo from
the endosperm, and the gradual reduction of the latter to
finer and finer particles. In this process the grain is passed
between successive pairs of corrugated iron rolls. The prod-
uct of each set of rolls is sifted, and the particles are graded

Io8 BOTANY OF CROP PLANTS

according to size, the coarser particles passing on to the
next set of rolls. Finally, the pericarp layers are com-
pletely separated from the adhering layers of aleurone and
starchy endosperm cells. The finely ground parts of the en-
dosperm are sifted and bolted. The material that will pass
through fine silk bolting cloth is called flour. The larger and
coarser particles that remain behind are known as middlings.
The middlings are then freed of particles of bran, i.e., purified,
and passed between several sets of smooth rolls; the product
of each set of rolls is taken to a machine which separates out
the fine flour. The number of grades of flour, and of other
products, will depend upon the number of sets of rolls, and
the mesh of the bolts to which the grain and its ground prod-
ucts are subjected. Mills differ much in the grades of
material turned out.

Kinds of Flour. — There are three general sorts of flour:
graham, entire wheat, and patent or straight bread flour.
■"Graham flour ^' is the product obtained by grinding the
entire kernel of wheat. Its name is after that of Sylvester
Graham (1794-1851), 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 "straight" or "standard
patent." It is usually a combination of the so-called "first
patent," "second patent," and "first clear" flours. About
72 to 75 per cent, of the total wheat is recovered as "straight"
or "standard patent" flour. It is composed of floury endo-
sperm alone. The ordinary bread flours belong to this
grade. Other products of the milling process are known as
"second clear" flour, used for low-grade bread, "red dog"
also used for low-grade bread or for cattle feed, and "shorts, "
"middlings" and "bran." About 25 per cent, of the grain

TRITICUM 109

is returned as shorts, middlings and bran. The composition
of these varies somewhat with the milling process.

Germination of Wheat. — The time required for germina-
tion depends upon external conditions. The optimum tem-
perature for the germination of wheat is close to 84°F., the
minimum 40° to 43°F., and the maximum io8°F. Germina-
tion will take place under field conditions usually within
from four to ten days. Nobbe finds that wheat will
begin to germinate in one and three-fourth days at
65°F., two days at 6o°F., three days at 5o°F., and six days
at 4o°F.

Three germinating stages in wheat are shown in Fig. 2.
The primary root is the first to appear. It ruptures the
coleorhiza which remains as a collar about the root where it
breaks through the grain coats. Very soon two lateral roots
appear; hence the primary root system consists of a whorl
of three roots. The growing point elongates, the first young
leaf being enclosed by the leaf sheath or coleoptile, a closed
and pointed organ. The coleoptile protects the growing
point and serves as a boring organ. The coleoptile of wheat
has the greatest soil-penetrating ability of the common
cereals. Its length varies with the variety and with the
depth of seeding. The closed end of the coleoptile is
broken by the first foliage leaf. The cotyledon (scutellum)
is left beneath the ground.

Repeated Germination. — The grains of wheat, and the seeds
of a number of other agricultural plants, are capable of
repeated germination. A grain may start to sprout, the
process be stopped by dryness, and sprout again if moisture
is available. Beal germinated wheat and buckwheat six
times, each time allowing the root and stem to grow to the
length of the grain, with the following results :

BOTANY OF CROP PLANTS
Repeated Germination

Kind of seed

Per cent, germinated

1st

4th

Sth

6th

Schumacher wheat

Clawson wheat

Buckwheat

lOO
lOO

loo

lOO
lOO
lOO

97
100

87
98
98

67
84
65

8
38
39

Classification of the Types of Wheat. — Hackel divides the
genus Triticum into two sections, Aegilops and Sitopyros.
In the first, the glumes are flat or rounded on the 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 iehakotn).

TRITICUM III

Spikelets more than two-flowered, two or more fertile; terminal spikelct
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.
spella (spelt).
Spikelets set thickly on stem; flattened on inner side; adhering portion
of rachis slender, pointed; stem above, with e.xception of narrow
canal, fiUed with pith. T. dicoccum (emmer).
Rachis tenacious, not articulated, remaining entire in threshing; spikelets
usually more than two-grained.

Empty glumes sharply and broadly keeled to the base; lemma
bearded.
Spike with sides parallel or nearly so; glumes with a bloom, usually
glabrous; grain very hard, horny, long. T. durum (durum
wheat).
Spike short, crowded, long-ovate; glumes usually pubescent; grain
short, blunt and softer than that of T. durum. T. lurgidum
(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. asllvum- (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 wheals,'' in which the grain comes free from the
lemma and palet, and the rachis is tenacious (2\ durum,
turgidum, compactum, cdsiivum, and polonicum) .

2. ''Spelt wheats," in which the grain remains altaclicd
to the lemma and palet, and the rachis is fragile {2\ ■moiio-
coccum, dicoccum, and spelta).

112 BOTANY OF CROP PLANTS

Beyerinck has succeeded in producing crosses of einkorn
with dicoccum, none of which were fertile, however. Aaron-
sohn says that T. polonicum hybridizes with the other species,
T. cEstivum and T. monococcum, but the offspring are not
fertile.

T. monococcum (einkorn) is a small-headed species of no economic impor-
tance in this country. It is cultivated to some extent in Spain, Germany,

Fig. 38. — Spikes of the types of wheat, i, PoHsh wheat (Triticum polo-
nicum) ; 2, club wheat (T. compactum) ; 3, common bread wheat (T. asstivum) ;
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.
Triliciim agilopoidcs is considered to be the wild form of our cultivated ein-
korn. This wild species is divided into the two subspecies: T. thaondar and
T. boeoticum. In the first, only the lower flower is fertile, as a rule, but botli
bear awns, while in hoeoHcum only the lower flower is fertile and awn-bearing.
There is a difference of opinion as to which of these stem forms is nearest to
our cultivated einkorn. T. cegllopoidcs differs from cultivated forms of
einkorn in that its spikes are more fragile, and the grains smaller and lighter
in color.

TRITICUM

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. dicoccitm (emmer) is of some economic importance in this country,
especially in the Western States.

T. durum (durum) varieties are also known as "goose," "wild goose,"
and "macaroni" wheats. They are hard wheats, particularly adapted
Id the arid regions, where they are better yielders than aslivum wheats.

Fig. 39. — Spikelets of the types of wheat, i, einkorn (Triticum monococ-
cura); 2, spelt (T. spelta) ; 3, emmer (T. dicoccum); 4, common bread wheat
(T. xslivum) ; 5, club wheat (T. compactum) ; 6, durum 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.
T. lurgidum (Poulard wheat) is of little consequence in this country. The
spikes are quadrangular or rectangular in cross-section. There is a tendency
to form branching spikes, as in Alaskan and Seven-headed or Egyptian
varieties. Such varieties also go under such common names as Stoner,
iMiraile, Eldorado, Jerusalem, INIany-headed, Many-spiked, Wild Goose, etc.

114 BOTANY OF CROP PLANTS

T. compaclum (club wheat) varieties are said to be adapted to tlie
Pacific Coast and Rocky Mountain States. In club wheats, the spikes
are only two or three times as long as broad, and typically broader
at the top than at the base, thus appearing somewhat club-shaped. 'I"lu'
joints of the rachis are very short, so that the spikelets are crowded and often
stand outright. J

T. (Bslivum (common wheat). — The bread wheats of the world are large!)-
varieties of ccslivum.

Origin of Wheat. — A few years ago, Aaronsohn brought
from Syria a wild emmer which was named by Koernicke
Trilicum dicoccum dicoccoides {T. licrmonis Cook) (P'ig.
40). Later, in an expedition in Upper Galilee to the north
of Lake Tiberias, he found this wild emmer again, and, on
Mount Hermon near the village of Arny, he found it very
common and in a variety of forms. This was at an altitude
of 1,500 to 2,000 meters. Chodat concludes that wheat is
indigenous to Syria. He considers that T. dicoccum dicoc-
coides, a form with a fragile rachis, is the primitive type
of wheat. It is interesting to note that the grains of this
"wild wheat" are not inferior in weight or size to those of
the best cultivated varieties.

It is well agreed that the prototype of our cultivated
wheats, whatever it is, is one with a fragile rachis. The rigid
rachis is considered to be developed by man. It is known
that the wheats cultivated in most ancient times were those
with fragile rachises, such as emmer. Furthermore, all
genera and species related to wheat, such as Aegilops and
Agropyron, etc., have a fragile rachis. The only cultivated
wheats of today with brittle rachises are einkorn, emmer,
and spelt.

It is observed that cross-pollination is more prevalent in
Aaronsohn's primitive wheat than in cultivated forms. This
may be due to the fact that it grows in a warm, dry climate,
while most cultivated wheats belong to northern cHmates,

TRITICUM

115

Imc;. 40. — Wild cimm-r ni PalcsUnc ( InLicuni dicoccuiii dicoccoi.

in experimental plat at Banl, California. (Cook. LI. S. Pep!, of Agr.)

BOTANY OF CR01> PLANTS

where cold or wet weather prevents Uower ()i)eniiig. In
India, it has been observed that cross-polh'nation 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 iirst 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. agilopoidcs Ihaoudar and dicoccoidcs. The
Fig. 41. — Spike- origin of the different types of cultivated wheats, as
let of wild ernmer given by Schulz, is shown in the following:
(Tnticum dicoc- t^- u ■ r i • u -f •; ^ -j • ^1

cum dicoccoides). '• ^'''koni scnes, of which f. a-gibpoidrs is the
X 21.;. prototype.

2. Emmer scries, of which T. dicoccoidcs is tlic stem
form. From this have come dicoccum, durum, lurt^iduiii, and poloiiicum.

3. SpcU series, of which the stem form is unknown. From this have come
spelld, compaclum, wslivuni, and capilalum.

Environmental Relations. — Wheat is grown under a wide
range of temperature conditions. Some varieties come to
maturity and yield well as far as 64° N. latitude in Norway,

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

WATER-REQmREMENT DETERMINATIONS AT AkRON, COLORADO, IQII, I912,

AND 1913, Based on the Production of Dry Matter

Plant Mean of genus

Proso 293

Millet 310

Sorghum 322

Corn 368

Wheat 513

Barley 534

Buckwheat 578

Oats 597

Rye 685

Beet, sugar 397

Potato 636

Pea, Canada field 788

Alfalfa 831

If the water requirement of proso millet is regarded as i,
the water requirement for the following crops is as follows:
millet 1.06; sorghum i.io; corn, 1.26; wheat 1.76; barley
T.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 fertihty of the
soil. The water requirement is greater in an unfertile than

Il8 BOTANY or 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 cUmate 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 alHed
products. In the manufacture of macaroni, the wheat is
first ground into a course product known as "semolina.''^

Fig. 42. — Diagram showing the percentage of the world's wheat crop pro-
duced by the different countries in 1915.

It is freed then of any adhering particles of fine flour and
bran. The semolina is mixed with about 30 per cent, of
water, worked into a stiff dough, and given a thorough
kneeding. The dough is then forced through a press, from
which it issues in long hollow tubes. These tubes of moist
dough are then carefully dried in a manner to prevent them
from becoming too brittle or sour. Vermicelli and spaghetti

TRITICUM

119

are also made from semolina and water, but dies of different
form are used, and drying is done on frames. Many sorts of
breakfast foods are made from wheat. A very recent prod-
uct is puffed wheat, in the preparation of which the kernels
are expanded by heating to a high temperature under pres-
sure, and then the pressure is suddenly released. The whole
grain, screenings, bran, shorts, middlings and "red dog" are
fed to animals. Sometimes wheat is sown with vetch and
the two together used for silage purposes. Wheat, as well
as other cereals, finds use in the manufacture of whiskey.
It is employed also in the making of weiss-beer malt.

Production of Wheat. — The leading wheat-producing
countries of the world are shown graphically in Fig. 42.
The following table gives the wheat production in the United
States for 1915.

Wheat Production in the United States, 191 5

State

Acres

Bushels

Total value
dollars

North Dakota... . r.

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

lUinois

Washington

Ohio

All other States

United States

59,898,000

1,011,505,000

930,302,000

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

o
<

iSSlssSss.s.sSSsS

ii.ii

iiSi

III!

ills

P-lsllllll

iiiiiiHii

illlliS!-!-!-

ssiisiisSs

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, 1910.
Beijerinck, M. W.: tJber den Weizenbastard Triticum monococcum 9?

Triticum dicoccum c?. Nederlandsch Kruidkundig Archief., ser. 2,
' T. 4: 189-201, 1886.
Bessey, C. E.: The Structure of the Wheat Grain. Nebr, Agr. Exp. Sta.

Bull. 32: 100-114, 1894.
Bloomfield, L. M. : Contributions to the Life History of the Wheat Plant

(T. vulgare). Ann. Rep. Ohio State Acad. Sci., 2: 12-14, 1894.
Brenchley, W. E.: On the Strength and Development of the Grain of Wheat

(T. vulgare). Ann. Bot., 23: 11 7-139, 1909.
Brenchley, W. E., and Hall, A. D. : The Development of the Grain of

Wheat. Jour. Agr. Sci., 3: 195-217, 1909.
Chodat, R.: a Grain of Wheat. Pop. Sci. Mo., 82: 33-46, 1913.
Cobb, N. A.: Universal Nomenclature of Wheat. N. S. W. Dept. Agr.

Misc. Pub. 539, 1905.
Cook, O. F.: Wild Wheat in Palestine. U. S. Dept. Agr. Bur. Plant Ind.

Bull. 274: 1-56, 1913.
DoNDLiNGER, P. T.: The Book of Wheat. Orange Judd Co., 1908.
Eriksson, J.: Beitrage zur Systematik des cultivierten Weizens. Landw.

Versuchsstat., 45: 37-135. 1894.
Fruwirth, C: Das Bliihen von 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, 1910.
MoBius, F. : Untersuchungen iiber die Sorteneinteilung bei Triticum vul-
gare. Inaug. Diss., Giessen, 1913. Druck von F. StoUberg, 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 Munster) fur 1910-1911, S.

147-152, 1911.

Die Geschichte des Weizens. Ztschr. Naturw., 83: 1-68, 1911.

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.

122 BOTANY OF CROP PLANTS

Die Abstammung des Einkorns (T. monococcum L.). Mitt. 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.

CHAPTER XI
AVENA (Oats)

Habit of Plant. — Oats are annual. The large majority of
varieties are summer annuals; a very few are winter annuals.

Roots. — The root system of oats is very similar to that of
wheat. The dense, fibrous growth, which in wheat occurs in
about the first foot of soil, is somewhat deeper in oats.
The roots of oats extend to a depth of 4 or 5 feet. To quote
from Ten Eyck, "Extending down from the center of the
root crown of each plant in this example was observed a short
rudimentary root stem which ended abruptly with a slight
enlargement from which radiated a few short, fine, wire-like
roots. Often the old seed coat was found 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 young 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

123

124

BOTANY OF CROP PLANTS

rolled to the left. The auricles are lacking, which also dis-
tinguishes it from the other cereals.

Inflorescence. — The spikelets of oats are arranged in a
panicle. The branching on the main axis is racemose, that

Fig. 44. — Diagram of oat inflorescence. (After Broili.)

of a higher order is cymose (Fig. 44). The number of
whorls in a panicle ranges from four to nine, mostly five or
six. Apparently, there are a number of primary branches
arising at a node. However, there is only one primary branch,

AVENA 125

the others being branches of higher order, arising at the base
of the primary. The branching decreases from bottom to top.
In banner oats {Avena orientalis), the panicle is one-
sided. In ordinary panicle or spreading oats (Avena saliva),

Fig. 45. — A, contracted, one-sided panicle of banner oats (Avena orientalis);
B, spreading inflorescence of panicle oats (Avena sativa).

the branches spread toward all sides (Fig. 45). Four main
types of panicle oats have been distinguished at the Svalof
Experiment Station, as follows: (i) Panicle stiff and upright,
(2) panicle pyramidal, the branches long, slender, and rising

126

BOTANY OF CROP PLANTS

weakly, (3) panicle widely spreading, (4) panicle with
branches weak and drooping.

The number of spikelets in a panicle varies, an average
number being near 75. The rachis is straight or only sHghtly
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 live, rarely it is one.
Three, however, is the usual number. In the so-called " single

^jlerile 3rd flower

Fig. 46. — Spikelet of panicle oats (Avena sativa). X 2>2.

oals,'' 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,

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 surrounded 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.

128

BOTANY OP 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

rachilla

starchy
endosperm

Fig. 47. — A, mature grain of wild oats (A vena fatua); B, 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 andC, X5;.D, Xio.

ones. Furthermore, there is no constant relation between
weight of grain per bushel and per cent, of hull. However, if
an oat variety is well adapted to a certain region, the per cent,
of hull is quite generally lower than if it is poorly adapted.

AVENA 129

There are marked differences in the basal and upper grains
of a spikelet. The basal grain is the largest and usually
bears an awn; the upper ones rarely have awns. A short
rachilla (Fig. 47), which bears the second grain, is at the
base of the lower kernel. This rachilla varies in length, shape
and hairiness in the different oat varieties. The second grain
commonly carries no rachilla, or only a fine, thread-like one
at the end of which is an immature grain or the mere rem-
nants of a third flower. The base of the outer grain is blunt,
while that of the inner is pointed.

The oat kernel (Fig. 47) is elongated and has a hairy
surface. As in wheat, the embryo forms a very small por-
tion of the kernel. A cross-section of the grain shows the
following coats: (i) lemma; (2) palet, of six to eight cell
layers; (3) pericarp, a thin layer of two or three rows of cells;
(4) testa, two layers of inner integument; (5) nucellus, one
layer; (6) aleurone layer, two rows of cubical cells (some-
times one) ; (7) starchy endosperm.

The starchy endosperm of oats, unlike that of wheat,
possesses no gluten, and hence it cannot be made into light
bread. In this respect it resembles barley. The double row
of aleurone cells also distinguishes the oat grain from the
wheat grain. The other grain coats and the embryo are
very similar.

Germination of Oats. — The cardinal temperatures (maxi-
mum, optimum and maximum) for oats are about the same
as they are for wheat.

The young shoot breaks out at the germ end, grows
underneath the lemma, and comes out at the brush end.
This method of growth is necessitated by the persistence of
the palet and lemma. The primary root, however, rup-
tures the hull. The coleoptile is closed. The first foliage
leaf is rolled.
• 9

130 BOTANY OF CROP PLANTS

Classification of Oats. — The common oat varieties in the
United States fall into three species: Avena sativa, A.
orientalis, and A. nuda. The latter two are sometimes
given as varieties of A. sativa.

Avena sativa (panicle oats). — The common oats belong
to this species. In these, the panicles are spreading in all
directions (Fig. 45). A considerable number of forms are
recognized. Four main types, based upon character of
panicle, were given on page 125. As to color of grain, there
are white, yellow, gray (winter oats), brown and black sorts.
Some are bearded and some are beardless.

Avena orientalis (banner, side, mane, or Tatarian oats) . —
The panicles of these species have erect branches which are
close to the main axis (Fig. 45). The] inflorescence is one-
sided, which character has suggested the common names
ascribed to it. There are beardless-white, bearded-white,
beardless-yellow, beardless-brown, and bearded-brown
varieties.

Avena nuda (naked or hull-less oats). — The grains of this
oat fall from the hull when threshed. It may be either a
spreading or side type.

Other Cultivated Oats. — In addition to the three common
species of oats given above, the following species are recog-
nized and cultivated in various parts of the Old World:
Avena strigosa (rough oats), A. hrevis (short oats), A. hyzan-
tina (Mediterranean oats) and yl. abyssinica (Abyssinian oats).

Avena fatua ("wild oats")* — The so-called "wild oat" is
often found in oat fields, and the "seed" may frequently occur
as an impurity in farm seed. The plant has slender stems,
which are long, and hence it usually stands above the culti-
vated oats. It has three flowers to a spikelet, and the awns
on the lemmas are strongly bent (Fig. 47), thus differing
from common oats. Again, it is distinguished from the

AVENA 131

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

In cultivated sorts, there appears occasionally the so-called
"false wild oats," differing in its characteristics both from
the cultivated varieties and the true wild oats. It differs
from the cultivated varieties in having the long twisted and
bent awns. The kernels, however, are similar to those of the
cultivated varieties.

Origin of Oats. — It is held by Haussknecht, Thellung,
Trabut, and others that all the varieties belonging to A.
sativa, A. orientalis, and A. nuda have originated from A.
fatua. Under cultivation, A. fatua has lost the fragility of
its articulations, its hairs and, in some instances, its awns.
A. strigosa and A. brevis are derived from A. barbata, a
species growing wild in the Mediterranean region, Persia,
Mesopotamia, west to Atlantic Europe and Great Britain.
A. ahyssinica is originated from A. wiestii, a species in-
digenous to North Africa and Arabia. A. byzantina has
come from A. sterilis, the so-called "animated" or "fly"
oats, a wild form frequent in the Mediterranean region.
Trabut has found in this region all forms of Avena sterilis
("sterile" oats), beginning with those that are small and
useless and ending with the forms now cultivated there.
Algerian oat {A . algeriensis) is the common cultivated variety
of the sterile oat.

All the forms of oats derived from A . 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 climate, such as is found in the region north

132

BOTANY OF CROP PLANTS

of the corn belt in the United States. Cool summers favor
the ripening of the grain; oats is a better crop than wheat
at high latitudes and altitudes. The white and black oats
are grown at higher latitudes than red and yellow sorts; the
latter are raised in the Southern States, some varieties
being sown as winter oats. Practically all of the oats grown
in the Northern States is spring-sown.

The water requirement of oats is greater than that of
any of the other common cereals. It will thrive on soils too
wet for corn and in general is better adapted to heavier soils.

Uses of Oats. — ^Large quantities of oats are consumed
annually in the form of rolled oats or oatmeal. The grain
is also a much valued horse feed, and not infrequently it is
fed to poultry. Oats are sometimes grown for pasture, and
also cut before reaching maturity as hay. It makes an ex-
cellent nurse crop. Oat straw is used as roughage for stock,
and as a bedding.

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

Leading Countries in the Production of Oats, Showing Acreage and
Production, 1915

Countries

United States

Russia, European

Germany

Canada

France

Austria-Hungary

United Kingdom

Sweden

Argentina

* No ofl&cial statistics.

40,780,000

1,540,362,000

44,787,000

1,006,983,000

650,000,000
481,035,000

11,365,000

9,051,000

234,924,000

234,924,000
195,169,000

4,149,000

70,000,000
62,392,000

2,869,000

AVENA 133

The Production of Oats in the United States, 1915

States

Acres

Bushels

Total value,
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
43,000,000
35,991,000
26,460,000
20,286,000
21,824,000
24,841,000
22,277,000
22,490,000
206,638,000

Illinois

North Dakota

South Dakota

Nebraska

Ohio

Indiana

Michigan.

All other States

United States

40,780,000

1,540,362,000

555,569,000

References

Atterberg, a.: Neues System der Hafervarietaten nebst Beschreibung der

nordischen Haferformen. Landw. Vers. Stat., 39: 171-204, 1881.
BoHMER, C: tJber die Systematik der Hafersorten sowie uber einige zuch-

terisch wichtige Eigenschaften der Haferispe. Eerlin, 1909, P. Parey.

Hafer im Bilde. Fiihling's Landw. Ztg., 609-616, 1911.
Broili, J.: Beitrage zur Hafer Morphologic. Jour. Landw., 58: 205-220,

1910.

Hafer im Bilde. Arb. Deut. Landw. Gesell. Heft., 194, Berlin, 1911.

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, 1912.
Denaiefe and Sirodot: L'avoine, etc. Paris, 1902, 210 figures, pp. 848.
Fruwith; C: Die Haferrispe bei der Beurteilung der Sorten und in der

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

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

134 BOTANY OE CROP PLANTS

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

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

58: 496-501, 1909.
RrMPAU, 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 und Heimat des Saathafers. Mitt. Thuring. Bot. Ver. N.

F. Weimar., 31: 6-1 1, 1914.
Tannert, Paul: Entwickelung und Bau von BlUte und Frucht von.Avena

sativaL. Inaug. Diss. Zurich, 1905.
Thellung, a.: Uber die Abstammung, den systematischen Wert und die

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

Naturf. Gesell. Zurich, 56:293-350, 1911.
Trabut, L. : Origin of Cultivated Oats. (Translation) Jour. Hered., 5 : 74-85,

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

149: 227-229, 1909.
ViERHAPPER, F.: Zur Systematik der Gattung Avena. Verhandl. K. K.

Zool. Bot. Gesell. Wein., 56: 369-370, 1906.
ZADE:'Die Zwischenformen von Flughafer (Avena fatua) und Kulturhafer

(Avena sativa). Fiihling's Landw. Ztg., 369-384, 1912.

CHAPTER XII

HORDEUM (Barley)

Habit of Plant, Roots, Stems, Leaves. — Barley is grown as
either a summer or winter annual. It has been observed
that two-rowed barley {H. distichon), has a distinct tendency
toward the perennial habit like rye.
Plants that were mowed down in
July sent up new sprouts which de-
veloped inflorescences the following
September, and after removing these,
a third set of sprouts was sent up.
It has been suggested that our culti-
vated barleys are derived from a
perennial form and that in the course
of time this habit has been lost.

The root system of barley resem-
bles that of oats. The culm has
from five to seven joints, sometimes
eight, the length of which increases
from below upward. Barley does
not tiller as abundantly as oats and
winter wheat. The leaves resemble
those of wheat. The auricles, how-
ever, are usually very much pro-
nounced, and may be used as a basis of distinction between
the straws (Fig. 26).

Inflorescence. — The inflorescence is a cyUndrical spike,
the shape of which varies slightly in the different barley
13 s

Fig. 48. — Rachises of
three common cereals.
A, barley; B, wheat; C,
rye. X 5-

136

BOTANY OF CROP PLANTS

types. The rachis is strongly compressed. Opposite each
point on the rachis where the spikelets stand, there is a
sharply defined horizontal cushion (Fig. 48). This dis-
tinguishes the barley rachis from that of wheat and rye.
Furthermore, the single joints of the barley rachis are
straight, while in wheat and rye they are bent.

Fig. 49. — ^.-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-
f urcatum) .

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

iiORDF.ri\r 137

no ;i|)iciil si)ikclcL 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-like, forming an apparent in-

FiG. 50. — I, triplet of spikelets of six-rowed barley (Hordeum vulgare
liL-xastichon); 2, of hooded barley (H. vulgare trifurcatum); 3, of medium
barley (H. vulgare intermedium); 4, of two-rowed barley (H. distichon). Nat.
size.

volucre about the spikelets. The lemma is broad, rounded
on the back, five-nerved at the apex and bears a long awn
with strongly barbed edges. In threshing barley care is
taken not to break the awn so close that the end of the kernel

138

BOTANY OF CROP PLANTS

is exposed, for by so doing, a point of attack for molds is

furnished.

The palet is about the same length as the lemma, and bears

two ridges. The styles are short, and the two lodicules are

conspicuous and vary in the
different types.

Opening of Flower and
Pollination. — The blooming
of a spike begins slightly
above the middle and pro-
ceeds from this point upward
and downward. The middle
flowers of a triplet come to
maturity earlier than the
laterals. The duration of
blooming varies. Three to
four days is a good average
for a single spike, and seven
to nine days for all spikes of
a plant. The glumes of a
flower remain open from
twenty to thirty minutes.
This period depends upon
weather conditions.

In two-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

- lemma

itarchv
endojpermi

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

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-polHnation, while in six-rowed, peacock,
and two-rowed erect barleys this possibility is excluded.
However, very few positive cases of natural hybridization
of barleys have been observed. The reason for this prob-
ably is that the styles are short and do not protrude beyond
the glumes. Rimpau examined a large number of sorts, and
in all, found but eight sure cases of crossing, and these were in
four-rowed barleys. Self-pollination is the rule, which means
that under field conditions there is little danger that a pure
strain will become impure through the introduction of
characters brought in by the pollen grains of undesirable
strains.

Blooming in barley begins between 5:30 and 6:00 a.m.,
increasing in intensity up to 8:00 a.m. Very little blooming
occurs in the middle of the day. There is a^ slight amount
between 3 and 5 o'clock in the afternoon, but by 8 in the
evening all blooming has ceased.

As in all cereals, blooming is dependent upon the weather.
Barleys that normally bloom with open glumes on a day with
high temperature and dry atmosphere, may bloom with
closed or only slightly open glumes on a cool, moist day.

Fertilization and Maturing of Grain. — The immature grain
has much the same structure as that of wheat. Kudelka
finds that, in barley, the chlorophyll-bearing layer consists
of two rows of cells, however. As in wheat, there is an
early resorption of the two layers of the outer integument,
and of pericarp and nucellar cells. The barley grain passes
through the milk-ripe, yellow-ripe, full-ripe, and dead-ripe
stages.

I40 BOTANY OF CROP PLANTS

Mature Grain of Barley. — In hulled barleys, the palet and
lemma are firmly attached to the kernel (Fig. 51). In the
so-called "naked" or hull-less barley, these scales come loose
from the kernel, as in common wheat. The kernel of naked
barley resembles that of wheat. It is, however, pointed at
both ends (Fig. 51). The kernels are broadest at the
middle, in two-rowed barleys, while in the four-rowed types
the kernels from the outer rows of the head are slightly
twisted and those from the middle rows are broadest near
the tip.

In the hulled barleys, a rachilla ("basal bristle") persists
at the base of the grain on the side adjacent to the palet
(Fig. 51). The character of this bristle is of some syste-
matic importance.

The hull may form from 10 to 25 per cent, of the grain,
being greater in six-rowed types than in two-rowed types.
Variation in percentage of glumes may depend upon season,
soil, grain shape, and perhaps fertilizers. Furthermore,
Haberlandt has shown that barleys of northern regions have
a smaller percentage of hull than those of southern localities.

In a cross-section of the mature grain of hulled barley, the
following coats are seen:

1. Lemma and palet, five to seven rows of cells.

2. Pericarp, consisting of several rows of parenchyma cells
and two rows of chlorophyll-bearing cells.

3. Testa, two layers of inner integument.

4. Nucellus, one row of cells.

5. Aleurone layer, usually of three (two to four) rows of
thick-walled cells.

6. Starchy endosperm.

As in rye and wheat, the fruit and seed coats are more
weakly developed at the embryo end than in other parts of
the igrain.

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 alkaHne condition; the other, a melanin-Hke compound,
is black. The pigments may occur in the hulls, the peri-
carp, the aleurone layer, and occasionally in the starch endo-
sperm. The resulting colors of the grain are quite compli-
cated. White denotes the absence of all pigment; a heavy
deposit of the melanin-like compound in the hulls results in
black; a light deposit, brown. Anthocyanin in the hulls re-
sults in a Ught violet-red. In naked forms the melanin-
like compound in the pericarp results in a black kernel;
anthocyanin produces a violet one. The acid condition of
anthocyanin in the pericarp superimposed upon the alkaline
condition in the aleurone layer gives the 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

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 ability to produce an abundance of the starch-
dissolving enzyme— diastase. Small grains, with a high
nitrogen content have a high power of forming the enzy-
matic secretions. The enzymes secreted during germination
are chiefly diastase, cytase, and proteases, and it is quite
probable that the epithelial layer of the scutellum is the
secreting organ. It has been pointed out by Mann and
Harlan that "the greatest secreting area for a given grain
is secured with a scutellum extending well over the edges of
the adjacent endosperm; the greatest vigor in an epithelial
layer of long, narrow cells, the highest condition of efl&ciency
in a well-matured, well-cured grain." As has been indicated,
the principal enzyme secreted by the germinating embryo
is diastase. It has the specific property of changing starch
to sugar. Hence, the reserve starch in the embryo, converted
to soluble and diffusible sugar, serves to nourish the young
plant. Cytase is a cellulose-dissolving enzyme. Protease
renders the insoluble proteins soluble.

The primary root is the first to appear. This is followed
by the secondary ones, and the young shoot. The shoot

HORDEUM

143

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

Jemma
/ yindicule
jtamen

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-

144 BOTANY OF CROP PLANTS

istic of barley. The term ^^ aero spire'' is sometimes applied
to these leaves.

The crown roots are formed at a rather constant soil level.
If the grain is planted deep, a long internode is formed, such
that adventitious roots are produced at the proper level.

Classification of Barleys. — There is much difference of
opinion concerning the classification of the cultivated barleys.
There are at least two distinct species: Hordeum vulgare, in-
cluding the six-rowed barleys, and Hordeum distichon,
including the two-rowed barleys.

Hordeum vulgare hexastichon (six-rowed barley). — It will
be recalled that, in the barleys, there are three one-flowered
spikelets at each joint of the rachis. In the six-rowed type,
every flower of a triplet is fertile. The spikelets are in six
distinct rows and stand out equidistant from the rachis.
Furthermore, the rows are equal distances from each other
about the axis. These points are shown in Fig. 52. The
lemmas of all three spikelets are bearded. The rachis inter-
nodes are very short, from 2.1 to 2.7 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 types are food barleys.

Hordeum vulgare (common six-rowed barley). — This is
sometimes called a four-rowed barley. Every spikelet is
fertile; the lemmas of all spikelets are bearded or hooded;
the "hull" is thick; and there is a high percentage of protein.
It differs from six-rowed barley in that the rows of grains are
not equal distances from each other about the axis (Fig.
52). The lateral grains of one triplet tend to overlap with
the lateral grains of the triplet on the opposite side of the
rachis. Hence, there will be found often four rows of grains,
the central grains of each triplet forming two rows and the

IIORDEUM 145

overlapping laterals also forming two rows. Furthermore,
in four-rowed barley, the rachis internodes are longer (2.8
to 3.5 millimeters) than those in six-rowed barley, and this
results in a more loosely arranged spike.

A form of four-rowed barley, Hordetim vidgare 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,
//. vulgare nigrum, black barley, and H. vulgare coelesle, the
hull-less Jerusalem barley.

Hordeum vidgare 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 ////(T/^/c^/mw forms are segregates
of the hybrids of certain two-rowed and many-rowed forms.

Hordeum disliclion (two-rowed barley). — In this, the
spikes bear two longitudinal rows of grains. As in six-rowed
barley, the spikelets occur in groups of three on opposite
sides of the rachis, but in the case of two-rowed barley, the
lateral spikelets of each triplet do not mature, only the middle
one of each maturing its grain (Figs. 49 and 52). However,
the glumes of the lateral spikelets develop normally. 'I'he
anthers of side spikelets may be either dwarfed or well
developed. The kernels of two-rowed barleys are symmet-
rical and broadest in the middle. The hull is thin. There is
a low percentage of protein and a mealy endosperm.

There are four rather common types of two-rowed barleys:

146

BOTANY OF CROP PLANTS

I. Uordeum dislichon 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 (Hordeuni dis-
tichon nutans); 2, medium barley (H. vulgare intermedium); 3, four-rowed
barley (H. vulgare pallidum); 4, hooded barley (H. vvdgare trifurcatum); 5,
six.-rowed barley (H. vulgare hexaslichon).

centimeters long, broad at the base and narrow at the tip,
and with widely spreading beards.

2. Uordeum dislicJion nudum (two-rowed naked barley).

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, 5, nodding barley
(Hordeum distichon nutans); C, D, erect-eared barley (H. distichon erec-
tum). (After Newman.)

4. Hordeum distichon nutans (bent or nodding barley). —
In this the heads hang down when ripe. On the dorsal side
of the grain at the base, there is a slight horseshoe-shaped
depression. In lengthwise section, the base of the kernel
slopes off (Fig. 54). Rachis joints are 2 .8 to 3.5 millimeters

148 BOTANY OF CROP PL.A^^TS

long. The rachilla is broom-form or very hairy. The noted
malt barley. Chevalier, belongs to this t>'pe.

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 erectum, 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 sLx-rowed
barleys.

Rimpau, on the other hand, considers the six-rowed
bearded barley as the prototv-pe of all other barley tjpes.
Through a process in which side spikelets become rudimen-
tary, there arose the various four- and two-rowed tx-pes.
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 "w-inter 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° X. 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 barlev. " Bqiey also does well in
southern Cahfornia.

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 utihzed 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-

150 BOTANY OF CROP PLANTS

ceed to the point when the young shoot (acrospire) breaks
out from under the lemma and palet, but the process is
checked by transferring the germinating grain to a kiln
where it is kept for about twelve hours at a temperature
sufficient to thoroughly dry it out. During germination,
there is secreted from the epithelial layer of the scutellum a
diastase which converts the starch to maltose sugar. Pep-
tase is also secreted by the germinating barley; this enzyme
modifies the albuminoids of the malt.

Mashing. — The malt, prepared as above, is cleaned, and
crushed in a roller mill. It is then mixed with water, and
in some cases with unmalted cereals. The mash is then held
at the proper temperature for the action of diastase and pep-
tase, which chemically invert the starch into maltose, malto-
dextrin and dextrin, and change the insoluble albuminoids
to a soluble form.

Boiling the Wort. — The product of the mashing machine is
called "wort." During the boiling process, hops are added.
Boiling serves not only to extract desirable products from
the hops, but to render harmless certain undesirable con-
stituents. After boiling, the wort is strained into coolers.

Fermentation. — Yeast is now added to the wort. This
introduction of yeast is called "pitching." Through the
activity of yeast, the sugar in the wort is changed to alcohol
and carbon dioxide. The wort has been changed to beer.
It is removed from the fermenting vat, stored for a period to
allow certain products to settle, and also to permit of after-
fermentation, and then clarified, filtered, and packed for
the market.

Production ,of Barley. — The four leading countries, in
1915, in the production of barley were: Russia, United
States, Germany, and Austria-Hungary, producing respec-
tively 475,109,000; 277,009,000; 150,000,000; and 136,186,000
bushels.

HORDEUM

151

ACREAGE) Production and Farm Value or Barley in Various
States, 191 5

States

Acres

Bushels

Farm value, Dec.
I. dollars

North Dakota

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
24,453,000
11,040,000
13,041,000
5,362,000
3,515,000
25,200,000

California

South Dakota

Wisconsin

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, 1912.
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 Bliihen der Gerste. Fiihling's Landw. Ztg., S. 544, 1906.
Harlan, Harry V.: Some Distinctions in Our Cultivated Barleys, with

Reference to Their Use in Plant Breeding. U. S. Dept. Agr. Bull. 137,

1-38, 1914.
Henning, E.: Beobachtungen iiber das Bliihen der Gerste (Schwedisch).

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

Gerste. Illus. Landw. Ztg., 830-839, 1909.
Johannsen, W.: Entwickelung und Konstitution des Endosperms der

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

hungen z'u den Fruchtstanden. Beiheft I der Naturwis. Ztsch. fur

Land- und Forstwirthschaft. Munchen, 1905.

152 BOTANY OF CROP PLANTS

Mann, Albert, and Harlan, H. V. : Morphology of the Barley Grain with

Reference to its Enzyme-secreting Areas. U. S. Dept. Agr. Bull. 183:

1-32, 1915.
QuANTE, Hugo: Die Gerste, ihre botanischen und brautechnischen Eigen-

schaften und ihre Anbau. Berlin, 1913.
RiMPAU, W. : Die genetische Entwicklung der verschiedenen Formen unserer

Saatgerste. Landw. Jahrb., 21: 699-702, 1892.
ScHULZ, A.: Die Geschichte der Saatgerste. Ztschr. Naturw., 83: 197-233,

1912.
Die Abstammung der Saatgerste, Hordeum sativum l-II. Mott. Naturf.

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

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

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

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.

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 differ-
ing from the other cereals. The root system branches pro-
fusely in the first foot of soil and extends to a depth of 4 or
5 feet.

Stems, Leaves. — As compared with wheat, oats and barley,
the stems of rye are tougher, slenderer, and longer. There
are commonly five to six, rarely four to seven stem joints.
The leaves are similar to those of wheat. The ligule is short
and somewhat rounded. The auricles are white, narrow and
wither early; sometimes they are absent altogether.

Inflorescence. — This is a spike. It is usually somewhat
longer than the wheat spike, and is rather uniformly four-
rowed. There are from 20 to 30 rachis joints. There is a
single spikelet at each joint. All the spikelets, from base
to tip, are fertile. The spikes have no terminal spikelet.

Spikelet. — Each spikelet (Fig. 55) consists of three flowers.
The two lateral flowers mature grains, the middle one aborts.
The glumes are very narrow; the lemma is broad, keeled,
and bears a long, terminal awn; the keel is strongly barbed;
the palet is thin, blunt and two-keeled. The lodicules are
IS3

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-fertiUzed
without a reduction in vigor and productivity. Apparently,

Pjq 25 — Rye (Secale cereale). A, a single spikelet at a joint on the
rachis; B, grain, external view; C, grain in cross-section. A, X 2j4; B and C,

xs-

no ill effects result from self-fertilization of barley, wheat and
oats. According to some observers, the pollen of rye is im-
potent on the stigma of the same flower. Fruwirth notes that
the flower is completely closed within twenty-five to thirty
minutes after it begins to open, providing the stigmas re-
ceive pollen. In case the stigmas are not dusted, the flowers
remain open much longer. Blooming begins between 5:00
and 6 : 00 a.m. and continues until 9 : 00 or 1 1 : 00 a.m. Then
blooming decreases throughout the afternoon, becoming

SECALE CERE ALE I 55

more rapid again in the evening. The first flowers to open
are slightly above the middle of the spike. It has been ob-
served that the flowers of rye can be induced to open by
rubbing with the hand, or by other mechanical stimulation.

Maturing of Grain, and Mature Grain. — The anatomical
structure of the ovary at blooming time is similar to that of
wheat, as are also the changes which take place in the grain
during its ripening.

The mature grain (Fig. 55) is free from the lemma and
palet. It is long, narrow, and usually darker in color than
wheat. The cross-section of the mature grain shows layers
similar to those in wheat, although different from it in details.

Rye protein usually forms about 6 to 12 per cent, of the
grain. Gluten is present in the protein, hence, the flour may
be made into porous bread. It wfll 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 87°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.

Environmental Relations. — Rye is adapted to colder and

156 BOTANY OF CROP PLANTS

drier climates than wheat, and will thrive on poorer soils
and more sandy soils than any of the other cereals.

Uses of Rye. — Rye flour is made into bread. A few break-
fast foods include rye as a minor component. Mixed with
barley, or corn, or shorts, or oats, rye grain is fed to stock.
In some sections it is grown for hay, or as a pasture crop, and
now and then as green manure. The straw finds consider-
able use as a stable bedding, as a packing material for nursery
stock, as a stuffing for horse collars, and it is also used inthe
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.
RiMPAU, W.: Die Selbst Sterilitat des Roggens. Landw. Jahrb., 6, 1877.
ScHULZ, August.: Die Geschichte des Roggens. Jahresbericht des West-

falischen Provinzial-Vereins fiir Wissenschaft und Kunst (zu 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 Bliihen beim Roggen.

Ber. Deut. Bot. Gesell., 22:445-449, 1904.
Das BlUhen des Roggens (Secale cereale). Ostrk. Landw. Wchnbl.,

1906, p. 163.
Die Bluh- und Fruchtbarkeitverhaltnisse bei Roggen und Gerste und das

Auftreten von Mutterhorn. Fuhlings Landw. Ztg., 55:194-199, 1906.
Ulrich, C: Die Bestaubung und Befruchtung des Roggens. Inaug. Diss.,

Jena, 1902.
WiTTMACK, L.: tJber die Stammpflanze des gemeinen Roggens, Secale

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

CHAPTER XIV
ZEA (Cora, Maize)

Habit of Plant, Roots. — Corn is distinctly a summer
annual.

The root system is fibrous. Corn generally has been con-
sidered a shallow-rooted plant. The contrary is the case.
At maturity the roots come to fill the upper 3 feet of soil and,
under some conditions, may reach to a depth of 4 or 5 feet
(Fig. 56). The depth of planting appears to bear no rela-
tion to the depth of rooting, for the first whorl of roots usu-
ally forms about i inch below the soil surface, no matter how
deep the seed is planted. It will be remembered that this
is true for the other cereals too. The roots of corn are thrown
off in whorls, varying in number from two to ten, one whorl
above another. The internodes between whorls are very
short. The entire group of whorls constitutes the root
crown.

Two kinds of roots are developed (Ten Eyck): {a) main
vertical roots and {h) main lateral roots. Vertical roots
curve out slightly from the crown and go directly downward.
The laterals curve downward, as they leave the crown, then
extend horizontally for a distance, finally taking a downward
course. Laterals that leave the crown at about the soil
level slope gradually downward, as indicated above. Midway
between the rows of planted grain, about 22 inches from the
157

158

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

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. De-pt. Agri,; B,
somewhat modified after Bailey.)

and wet seasons. The roots of most plants are more super-
ficial in a heavy or wet soil than in a light and drier soil.

ZEA 159

This is quite likely a response to oxygen supply, as well as to
moisture supply. The amount of oxygen in the soil decreases
as the depth increases. Moreover, the rate of decrease is
greater in heavy or wet soils than in light or dry soils. When
it is understood that every living root cell derives its oxygen
for respiration from the soil air immediately surrounding
and that the oxygen does not diffuse to any extent from the
aerial parts of the plant down through the stem to the roots,
we see the probable explanation of the fact that a shallow
root system is peculiar to a heavy or wet soil. In this con-
nection, it should be stated 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 3^ inch of the sur-
face. The depth of the corn roots determines the depth of
cultivation. If it is so deep as to destroy roots, the yield
is decreased.

"Prop" or "Brace" Roots. — In addition to the ordinary
underground roots, corn develops aerial roots, the so-called
"prop" or "brace" roots (Fig. 56). These' arise in whorls
at successive levels above the surface, extending obliquely
downward. They are covered with a mucilaginous sub-
stance which protects them from drying out. As aerial
roots, they are unbranched, but they branch profusely when
they strike the soil. They have the role of absorption, then,
as well as anchorage.

l6o BOTANY OF CROP PLANTS

Stem. — Corn is the largest of the common cereals. How-
ever, no other cereal varies so in size. There are dwarf forms
scarcely 3 feet high, while some are 15 or more feet high.
The stem is jointed as in all grasses. The internodes, how-
ever, are not hollow, but are filled with a soft pith through
which run numerous vascular bundles, the fibers. The
nodes are solid as in other grasses. The internodes are
furrowed on the side next the leaf blade. The corn plant
produces '^ suckers^' which correspond to the "stools" of
wheat, as to their morphology. "Suckers" are secondary
stems or branches arising from the lower nodes. These
branches develop their own roots. "Suckers" of corn are
undesirable, for they do not, as a rule, produce ears, although
they are heavy soil "feeders."

Leaves. — The leaves are arranged alternately on opposite
sides of the stem as in all grasses. They vary in number from
8 to 20. The blade is long and flat; the ligule closely invests
the stalk, acting as a rain-guard. Water that runs down the
stem and leaf blade is prevented from entering the space
between the culm and leaf sheath by this tightly fitting
ligule.

The corn leaf is thrown into a number of folds along the
edges and at the base. This is due to the more rapid growth
of the cells at these points. The corn plant is moderately
well adapted to dry conditions. An examination of the
leaf structure explains this. On the upper surface of the
leaf blade, along either side of the midrib, are a number of
large wedge-shaped cells; these absorb water readily in moist
weather, become turgid, and thus flatten the leaf out. In
dry weather, these cells lose their turgor. Hence the leaf
rolls up, presenting a smaller evaporating surface. In addi-
tion to this adaptation to dry conditions, the cuticle of the
lower surface of the leaf is much thickened, and the water

ZEA

l6l

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

FiG. 57. Pistillate and staminate inflorescences of corn (Z

ea mays).

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

l62

BOTANY OF CROP PLANTS

the stamens and pistils are borne in separate inflorescences on
the same plant (Fig. 57). The staminate
tlowers are in a panicle at the top of the
stalk; this inflorescence is known as the
'Uassel." 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-hke. 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 iive-nerved and the palet
two-nerved. The two lodicules are fleshy
and truncate. The anthers are long. The
upper flower of a spikelet matures first; its
palet is larger than the lemma, while in the
lower flower, the lemma is larger than the
palet.

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

Fig. 58.- a
single branch of
the staminate in-
florescence of
corn (Zea mays).

Characteristics.

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

6pikelet

Fig. 59. — A pair of staminate spikelets of corn (Zea mays).

reduced, the leaf sheaths alone remaining. The collection
of leaf sheaths on the shank forms the "husk" of the ear.
The pistillate spikelets are arranged in rows along a fleshy
axis, the "cob."

164

BOTANY OF CROP PLANTS

What Is the "Ear," Morphologically? — There are two
theories as to the morphology of the ear of corn. The view
of Hackel and of Harshberger is that the ear is the result of
a fusion of a number of two-rowed
pistillate spilces. 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 beHef may be
summarized as follows :

1. He has found tassels in which a
few pistillate flowers were found on the
central spike, also tassels in which the
central spike had developed into a fair-
sized ear of corn.

2. He observed a case in which the
lateral spikes as well as the central one
had developed pistillate flowers, form-
ing a number of four-rowed "nubbins"
surrounding a central well-developed
twelve-rowed ear.

3. The central spike develops pistil-
late flowers much more readily than the
lateral ones of the tassel. The central

spike has the greater number of rows of spikelets.

4. He has observed the development of pistillate flowers
from staminate ones. This development is as follows:

Fig. 60. — Longitudinal
section of staminate
spikelet of Country Gen-
tleman sweet corn, X 1 5 .
G, glume; Pa, palet; An,
position of one of the
lateral anthers; L, lem-
ma; A, dorsal anther.
P, rudimentary pistil; /,
joint of rachilla. (After
Weatherwax.)

ZEA 165

(a) Pedicellate spikelet shortens and becomes sessile; the
difference between the two flowers of this becomes greater.

(b) The lower glume shortens and thickens.

Fig. 6r.- — Corn (Zca mays). Young pistillate infLjrescence ("ear"), showing
the long styles ("silks").

(d) Sessile flower becomes pistillate.

(e) Both flowers become pistillate.

l66 BOTANY OF CROP PLANTS

Recently East and Hayes have expressed an opinion very
similar to that of Montgomery. Quoting from them, "The
ear of maize, then, is a meristic variation produced from the
central spike of the tassel of the lateral branches of teosinte
or of a teosinte-like plant, and not a fusion of the lateral
spikelets." Montgomery suggests that teosinte and corn
had a common ancestor, which was a "large, much-branched
grass, each branch being terminated by a tassel-Hke structure,

J^ glume

lemma of

ferhle '

jlower

^Znd ^lume
Fig. 62. — Pistillate spikelet of corn, much enlarged. {After Necs.)

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 being 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 entire!}- enclosed in the leaf sheaths" (the husks).
Pistillate Spikelet. — Each normal pistillate spikelet has two

ZEA

167

flowers, the lower one of which is abortive^ (Figs. 62 and 63).
The palet and lemma of the abortive flower remain, and form
a part of the "chaff" on the cob. The spikelet is subtended

Fig. 63. — Longitudinal section of pistillate spikelet of Black Mexican
sweet corn, X 25. 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; G, glume; Sta, rudimentary stamen; P, pistil of aborted flower;
J, joint of rachilla. (After Weatherwax.)

by two glumes that are shorter than the ovary, very broad
and 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.

1 68 " BOTANY OF CROP PLANTS

on the edges. The lemma and palet of the fertile flower are
short, broad and membranous. In pod corn, glumes, lemma,
and palet attain a considerable size and enclose the grain.
The single ovary bears one long style, the corn "silk," which
is forked at the tip. It is well to remember that there is one
silk for each grain on the cob. Weatherwax considers the
corn silk a compound stigma rather than a style. The silk
is indeed receptive to pollen a good portion of its length,
possibly all. A hot, dry wind may wither the silks, thus
destroying their receptivity to p|ollen. FertiUzation of the
ovules consequently does not take place, and the ovules do
not mature. The short protuberance at the top of the ovary
is considered by Weatherwax to be the style. It is traversed
by a canal, the stylar canal. Three small rudimentary
stamens have been observed by Baillon, and Weatherwax, in
the fertile flower; the lodicules are absent. The small
aborted flower has rudimentary stamens and pistil about
equally developed; the lodicules are present.

Hermaphroditic Flowers. — Ordinarily in corn the flowers
are imperfect, that is either staminate or pistillate. Perfect
or hermaphroditic flowers sometimes occur, however. Herma-
phroditic flowers are far more common on the tassel than on
the ear. East and Hayes record a sterile dwarf mutation
which had nothing but hermaphroditic flowers. Hermaphro-
ditic flowers have the stamens reduced. Lodicules are well
developed in staminate flowers, reduced in hermaphroditic
flowers, and altogether absent in fertile pistillate flowers.
Montgomery observed hermaphroditic flowers on normal
types of ears. The plants from these seeds came true to
type. The seed was normal in every respect except that it
had three fully developed stamens coming from near the
base of the ovary. There were also three small stamens in
the aborted flower of each pistillate spikelet. The plants

ZEA 169

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

Opening of the Flowers, and Pollination. — Cross-pollina-
tion, consequently cross-fertilization, is the rule in corn but
self-fertihzation 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 corn as to the
time elapsing between the appearance of anthers and appear-
ance of first silks, Gernert finds marked variation. Both
dichogamy (maturation of pollen and stigmas at different
times) and homogamy (simultaneous maturity of pollen and
stigmas) may occur. Furthermore, in dichogamous indi-

1 70 BOTANY OF CROP PLANTS

viduals, protandry (anthers mature first) or protogyny
(stigmas mature first) may occur. Out of 2,794 individuals
in 59 varieties examined, he found 243 individuals homoga-
mous, 92 protogynous, and 2,459 protandrous. It appears,
then, that protandry is the rule in corn. In protandrous
individuals, the first appearance of silks occurred from one to
twenty-three days after pollen shedding, although the aver-
age is two days. Varieties of corn dealt with in the above
were pod, pop, flint, dent, soft, and sweet. Collins records
the discovery of the protogynous habit in a variety of maize
introduced from Granada, Spain. Ordinarily, however,
dichogamy is seldom pronounced enough to completely ex-
clude self-pollination.

Gernert has also made observations as to the number of
days intervening between the appearance of tassel and
anthers. He finds, out of 3,319 individuals in 57 varieties,
that, in the greatest number (514), the anthers appeared
nine days after the tassel, and that in more than half of
the individuals the first anthers appeared in seven to ten
days after the tassels bearing them appeared.

Pollen is produced in great quantities. It is estimated
that each tassel produces 20,000,000 to 50,000,000 grains of
pollen. Lazenby estimated that for each ovule in dent
maize there are about 45,000 pollen grains produced.

The size of pollen grains in corn varies. Pollen produced
by central spikes is larger than that produced by laterals.
Livingston observed that in Leaming corn the pollen grains
from the central spikes were 0.02 milKmeter larger on the
average than those from lateral spikes. Of 12 varieties
examined, Gernert finds that the average diameter of the
pollen grain of corn varies from 0.08 to o.i millimeter.
They are rather ellipsoidal in shape. Corn pollen soon
shrivels after being shed, but its germinating power is not

ZEA 171

destroyed by this. However, pollen does not remain 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 polhnate all the silks of an ear.
Unfavorable cHmatic 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 corn is bent from the perpendic-
ular so that the silk, instead of pointing directly out from
the cob} points in a direction longitudinal to the cob. The
ovary is on a stalk (rachilla) about 2.5 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. Smgle row of epidermal cells.

2. Many layers of parenchyma tissue, varying somewhat in
size.

3. Single layer of inner epidermal cells.

True records the presence of a pit "a short distance from

172 BOTANY OF CROP PLANTS

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

The outer and inner integuments vary in thickness from
two to four layers. The very large embryo sac is located at
the base of the nucellus.

After fertilization, the following changes take place in the
maturing grain:

1. Outer integument disappears.

2. Cells of inner integument become flattened, due to
pressure from within.

3. The middle and inner cells of pericarp become compacted.

4. Cells of nucellus disappear to a large extent.

5. Hardening of the cell walls of the pericarp.

6. Fusion of pericarp and inner integument.

Xenia in Com. — ^Xenia is the term appUed to the phe-
nomenon in which some character of the male appears at
once in the seed. For example, in crossing a strain of corn
having yellow endosperm with a strain having white endo-
sperm, the grains produced are all yellow in every case, no
matter which is used as the male parent. Xenia is- shown
only in case the parent having yellow endosperm is used as
the male parent. The yellow endosperm character is
dominant over white endosperm. Pollen from the plant
bearing yellow endosperm will carry this character; pollen
from the plant bearing white endosperm will carry the white
character. When pollen, bearing the yellow endosperm
character, is placed on the stigma of the grain having white
endosperm, the pollen tube will discharge into the ovule two
male nuclei, each bearing the character for yellow endosperm.
One sperm nucleus fuses with the egg nucleus, the other
sperm nucleus fuses with the two polar nuclei. The result
of this triple fusion (second sperm nucleus and two polar
nuclei) is the endosperm. Now, since yellow is dominant,

ZEA 173

the grain that is formed by this double fertilization will have
a yellow endosperm. Thus double fertilization explains
the phenomena of xenia. It is of course true that, if in the
above, pollen from the white endosperm-bearing plant were
used, xenia would not be shown. Xenia, the visible effects
of double fertilization, has been found in the following con-
spicuous cases in corn— in each case below, the plant men-
tioned first is the female :

Non-starchy-seeded plants crossed with starchy-seeded
plants always give starchiness.

Non-yellow endosperm crossed with yellow shows yellow.

Non-colored aleurone layer crossed with purple gives
purple.

Non-colored aleurone layer crossed with red gives red.
/variation in the Corn Plant. — There are marked individual
differences in the plants of an ordinary field of corn. The
plants may vary in height, vigor, leaf production, height of
ears on the stalk, shape of ears, composition of kernel,
etc. Moreover, there is scarcely any other crop plant in
which we find more abnormalities or monstrosities than we
do in corn. We have mentioned hermaphroditic flowers,
both in the tassel and ear as one abnormality; to these we
may add branched ears, tassels with a few or many kernels,
variegated leaves, and variegated ears. In corn it is possible
for the different kernels of an ear to receive pollen from many
different plants, and from its own tassel. Hence, it usually
happens that the grains on the same ear have different
hereditary characters as shown by their varied progeny.
This is well shown in variegated ears. If xenia occurs, the
effects of this crossing may be evident the same season. For
example, if pollen from dent corn fertilizes some of the ovules
on an ear of sweet corn, those ovules appear starchy, while
the other grains of the ear of corn, fertihzed with sweet corn

174

BOTANY OF CROP PLANTS

pollen are wrinkled. If xenia does not occur, the results of
the mixing will not show up until the second year. Hence,
ordinarily even though an ear of corn appears uniform, the
separate kernels may have different heredity. The only way
of testing its purity is to plant the grains and observe their
progeny. Of course in this test, care must be taken to pre-
vent strange pollen from blowing in. This is practically ac-
compHshed by isolating the test plots.

Results of Self-fertilization in Corn. — If our ordinary
field strains of corn are self-fertiHzed for several generations
the yield is considerably reduced. However, as a result of
this inbreeding, we may be sure that all the kernels on an ear

Fig. 64. — Corn (Zea mays). ^, median lengthwise section, cut parallel to
broad surface, of grain of dent corn; B, cross-section of same through the
embryo; C, section as in A of flint corn.

have the same hereditary qualities. Furthermore, artificial
self-fertiHzation for five or more successive years results in a
strain that is not so complex in its characters, that is, a race
which is comparatively uniform and pure.

The Mature Grain of Com. — The mature grain of corn
varies considerably in shape (Fig. 64). In most varieties,

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 found the papery remains ("chaff") of the palet,
lemma, and glumes of the pistillate spikelets. The point of
the grain, where it was attached to the cob, is the peduncle
of the flower. The opposite indented end of the grain is
often marked by a small point which is the remnant of the
style. A longitudinal section of the corn grain parallel with
the broad surface will show, with magnification, the follow-
ing parts.

1. Pericarp, of several layers.

2. Testa, inner integument, of two layers.

3. Nucellar tissue.

4. Aleurone layer, outermost layer of endosperm, a single
row of cells.

5. Starchy endosperm.

6. Horny endosperm.

7. Embryo.

8. Tip cap.

The pericarp and testa form the hull. It is possible to
separate mechanically the starchy endosperm into two parts,
the crown starch and tip starch.

The following is a fair average of the relative proportions
of the divisions of the grain, as given by Hopkins, Smith,
and East:

Per cent.

Embryo 11. o

Tip cap 1.5,

"Hull" 6.0

■ Aleurone layer 8.0 to 14.0

Horny endosperm 45 . o

Starchy endosperm 25.0

176 BOTANY OF CROP PLANTS

Of course, there is a marked variation in the proportions
of these parts, and in their chemical composition.

Chemical analysis of the above parts shows' that the hull
contains less protein (about 4 per cent.) than any other part
of the grain. The endosperm is richest in protein, containing
20 to 25 per cent. The horny endosperm contains about
go per cent, starch and 10 per cent, protein. The starchy
endosperm is poor in total amount of protein (5 to 8 per

Fig. 6«;. — 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 corn kernels, the horny endosperm ex-
tends up to and comes into contact with the embryo,
the tip starch being entirely separated by it from the crown
starch. In low-protein corn kernels, the amount of horny
endosperm is reduced, tip and crown starch being continuous
between it and the embryo. The embryo is much larger in
high-oil kernels than in low-oil kernels.

ZEA 177

Embryo. — In the normal 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 jor 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, "i?tce.

Grains large, polygonal or rounded; hilum with clefts. Maize.

Germination of Com. — The germination of corn may be
judged from the following data: Sachs says: optimum 9i°F.,

178 BOTANY OF CROP PLANTS

maximum ii4.8°F., and minimum 4i°F. Sturtevant further
shows that corn germinates in from ten to twenty days at
a temperature of 43.7°F., while at from 48.6°F., to 58.5°F.,
it germinates in from five to ten days. In germination, the
primary root appears first, at the tip of grain; soon the plu-
mule breaks through the pericarp at about the middle of the
grain. The young germinating grain consists of a primary
root projecting at the peduncle end, and the plumule emerg-
ing through a slit in the pericarp at about the middle of the
grain, and pointing in the opposite direction. On the sides
of the primary root, two secondary ones soon appear, making
a total of three roots in the primary root system.

In the seedling, there is, as in other cereals, a more or
less elongated axis between the base of the coleoptile and
the grain. This has been named the mesocotyl by some mor-
phologists. Collins described seedlings of maize grown by
the Indian tribes of the southwestern United States, that
may develop, under conditions of deep planting, a mesocotyl
up to 36 centimeters in length.

Classification. — The many different varieties of cultivated
corn are all included under the one name, Zea mays L.
Sturtevant has divided this species up into "species groups"
(subspecies), the most important of which are the following:*

1. Zea tunicata, pod corn.

2. Zea everta, pop corn.

3. Zea indurata, flint corn.

4. Zea indentata, dent corn.

5. Zea amylacea, soft corn.

6. Zea saccharata, sweet corn.

7. Zea amylea-saccharata, starchy sweet corn.

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

ZEA 179

Gerncrt 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

Fic. 66.— The six principal lypos of corn. Fr(.in k-U to rik'lit. P
pop corn, flint corn, dent corn, soft c(5rn, and sweet corn. {After Montgom-
ery.)

canina Watson, the Mai/ de Coyote, is a branching plant
producing many small ears (2 to 4 inches long) on lateral
branches. It has been produced artificially by cros.sing 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, tlinty grains. Zea mays hirla is a
hairy, South x\merican corn. Zea mays ciiragiia is a forni
with serrate leaves.

l8o BOTANY OF CROP PLANTS

The distinguishing characteristics of the seven groups above
are shown in the following key:

Key to "Species Groups" of Corn

Each kernel enclosed in husks (glumes, lemma, palct); the ear is also
enclosed in husks; a rare form, considered by some to be the primitive
type, Zca litnicata (pod corn).
Each kernel naked, not enclosed in pod or husk:

Grains with popping properties; popping is due to the turning inside out of
the kernel through the explosion of the contained moisture when heat
is applied; pericarp is thick and tough; excessive proportion of horny
(corneous) endosperm; kernels and ears small, Zea everta (pop corn).
Grains without popping properties

No corneous endosperm, hence grains are-soft; shaped like flint corn;
no indentation; the mummy corns of Peru, Mexico, and southern
United States probably belong to this group, Zea amylacea (soft
corn).
Corneous endosperm present.
Grains more or less wrinkled or shrivelled; kernels horny and trans-
lucent in appearance.
Grains horny throughout, Zca saccharala (sweet corn).
Grains with upper half horny and translucent, the lower half
starchy, Zca amylca-saccharala (starchy sweet corn).
Grains not wTinkled, 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), Zca indcnlata (dent corn).
Starchy endosperm enclosed by the corneous endosperm; hence
there is no shrinkage of top of grain and no dent formed (Fig.
64), Zca iudiirala (flint corn).

Zea amylea-saccharata (starchy sweet corn) is a group of
only botanical interest. Some seed of this was found in the
San Padro Indian collection 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 saccharala, the power to develop starch grains to
maturitv has been lost. The starch that is formed remains

i8i

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

Fig. 67. — Tcubiulc ^.l:;uchlacna me.xicanaj. {AJ'ti-r Collins ami Knnpton in
Journal of Ilercdily.)

as dent, tlint, and [)op corns that have lost the power to
mature starch normally.

Origin of Maize. — Although maize or Indian corn has been

l82 BOTANY OF CROP PLANTS

in cultivation since prehistoric times, it is unknown in the
wild state. It is generally agreed, hawever, that it is dis-
tinctly of American origin. The nearest known wild relative
of maize is a Mexican grass, leosinle {EiicJilcena mcxicana),
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 Andropogonete. 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 ])cing southern
Wisconsin and Minnesota. This is a region with warm sum-
mer days and nights. The chief limiting factor to corn grow-
ing in the northern tier of States is cool nights.

ZEA 183

Reference to page 117 shows that the water requirement
of corn stands between that of sorghum and wheat. There
is a significant difference in the water requirement of the
varieties of corn, indicating that some may be more drought-
resistant than others. Corn is being raised with profit on
the dry lands of the West.

There is a close correlation between the yield of corn and
the rainfall for June and July. The critical month is July.
Smith says that the most critical ten-day period for corn, in
Ohio, is from August i to 10, the period following blossoming,
when the weather must be wet and moderately cool.

In the corn districts west of the 95th meridian, hot winds
sometimes prove fatal to corn. These winds are particularly
harmful during the critical periods of "tasseling" and
"silking."

Corn thrives best in a well-drained, medium loam soil, such
as is found in the river bottoms of the Mississippi Valley. It
will grow on soils so rich in nitrogen as to cause the lodging
of the small grains.

Uses of Com. — No other cereal is put to such a variety of
uses as is corn. • Some economical use has been found for
nearly every part of the plant. There are numerous manu-
factured corn products and by-products. Corn meal, both
yellow and white, is one of the chief forms in which the grain
is used as a food for man. Whole meal includes the embryo,
endosperm and hull, while new process meal has the embryo
and hull removed. Other forms in which corn as a human
food is used are: hominy, green corn, canned corn, corn oil,
corn flakes, pop corn, starch, and glucose. The sweet corn
canning industry is a large one. Corn starch from which
the protein and mineral matter have been removed by treat-
ment with dilute alkaline solutions gives a flour which is used
largely in the preparation of puddings, blanc manges, etc.

184 BOTANY or 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 vulcanized into a cheap grade of rubber.

Corn Starch. — About 50,000,000 bushels of corn are used
annually in the United States in the manufacture of com-
mercial starches, and products derived from them. In the
manufacture of corn starch, the corn is steeped from two to
four days in warm water containing about 0.2 per cent, of
sulphurous acid. Steeping is instituted in large wooden vats
holding about 2,000 bushels of corn. When the grains are
softened sufficiently, they are lead through a Fuss mill which
thoroughly breaks up the grain. The embryos are separated
from the rest of the grain material, and removed to another
receptacle. The disintegrated grains are freed from the
embryos, mixed with water, more finely ground and then
shaken through bolting-cloth sieves. Starch and gluten pass
through the sieves, while the courser materials, such as frag-
ments of the pericarp, are caught by the sieve. The liquor
containing starch and gluten is passed over tables, very
slightly inclined, and as the liquid slowly flows down these
tables, the starch granules settle, while the lighter particles
of gluten are carried off the lower end. The starch is re-
moved from the tables, washed, and kiln-dried.

Glucose. — The commercial "glucose" is a thick syrup — a
product of the partial hydrolysis of starch. The manufac-
ture of corn starch has been described. The "green
starch" from the tables is made into a thick cream by mix-
ing with water. This is then passed to converters where
the starch is treated with hydrochloric acid to bring, about
its partial hydrolysis. The converted liquor is blown out
of the converters into the neutralizer, where it is treated

ZEA 185

with a dilute solution of sodium carbonate, which neutralizes
the acid, and precipitates the dissolved iron, and coagulates
the colloidal albuminoids. The neutral liquor is then filtered,
first in bag filters, and then in bone-char filters. From the
first bone-char filters, there issues a light liquor. This is
evaporated to increase its concentration, and passed on as
heavy liquor to the bone-char filter again. The liquor that
results from this second filtering is boiled down in vacuum
pans, whence it comes as the finished glucose.

Pure glucose syrup has Httle flavor, and but half the sweet-
ness of cane syrup. Maize syrup is mixed with varying
quantities of cane syrup and sold as a substitute for golden
syrup and molasses. It is the basis of many manufactured
jellies and preserved fruits.

Grape Sugar. — This is a crude sugar made from starch,
in a manner very similar to that employed in the manufac-
ture of glucose. However, hydrolysis is more complete, the
process of conversion being carried to the point that no dex-
trin is precipitated when a sample is placed in strong alcohol.
Grape sugar appears on the market as a hard, waxy solid.
It finds considerable use in the manufacture of sparkling
ales; and, also, as a reducing agent in indigo dyeing, and other
industries.

Artificial Gums. — These are known as dextrins and British
gums, and are made from starch. Starch is heated to a
temperature varying from 170 to 27o°C. During this proc-
ess, the starch may be treated with dilute nitric acid to bring
about hydrolysis, although if high temperatures are used,
the addition of acid is unnecessary, as the starch itself con-
tains enough acid and water to effect hydrolysis. Dextrins
and British gums are used on envelopes and postage stamps,
and also in many of the textile industries.

Stock Food. — Corn fodder includes the whole plant — stalks,

1 86 BOTANY OF CROP PLANTS

leaves, and ears — and in this form is fed to stock. Corn
stover is the stalks of corn from which the ears have been
husked; the stalks may be fed in the bundle form or shredded.
Fodder is an important silage crop. In the form of silage,
it makes a highly nutritious, succulent feed throughout the
winter. Silage is a forage prepared by fermenting green,
fresh, plants in a specially constructed air-tight receptacle,
called a silo. The material to be ensilaged is cut into fine
pieces and packed into the silo. Forage crops include, ac-
cording to common usage, those plants which are grown
for their vegetative parts and which are eaten, either in the
green or dry state, by herbivorous animals. Some plants,
such as sorghums, are grown for their grain and also for
their herbage, that is, they are both a cereal and a forage
crop. Corn Is also both a cereal and a forage crop. The
grass family (Gramineae) and the pea family (Leguminosae)
furnish the great majority of forage plants. Corn grain and
corn bran are important stock foods.

Other Corn Products. — The pith from the stalks is made
into explosives and also employed as a packing material
where extreme lightness 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 com
gives about 90 gallons of 94 per cent, alcohol.

Production of Com.^ — In 1914, the United States produced
2,672,804,000 bushels of corn, which was over 70 per cent,
of total production for the world. The country ranking

ZEA 187

second in its corn output was Argentine with 338,235,000
bushels. The ten leading States in the order of their pro-
duction of corn in 191 5 were 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
1 91 5 corn crop, on the basis of the price of corn December i,
was $1,755,859,000.

Fig. 68. — Percentage of the world's supply of corn produced in the various
countries in 1914.

References

BoHUTiNSKY, GusTAv: EntwicklungsabweichuDgen 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.
BxiRTT, Davy J.: Botanical Characters of the Maize Plant. Transvaal

Agr. Jour., 7: 34-8-395, iQOQ-
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.

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, j : 293-302, 1914.
CoRRENS, C: Untersuchungen uber 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 Corn. Pop. Sci. Mo., 82:225-236, 1913.
East, E. M., and Haves, H K.: Inheritance in Maize. Conn. Agr. Exp.

Sta. Bull. 167:1-142, 1911.
Fisher, M. L.: Report of Work in Corn Pollination, I. Proc. Ind. Acad.
Sci., 1908.
Report of Work in Corn Pollination, II. Proc. Ind. Acad. Sci., 1910.
Report of Work in Corn Pollination, III. Proc. Ind. Acad. Sci., 191 1.
Gager, C. S.: An Occurrence of Glands in the Embryo of Zea Mays.

Bull. Torrey Bot. Club, 34: 125-137, 1907.
Gernert, W. B.: Methods in the Artificial Pollination of Corn. Am.
Breeders' Assn., 7: 353-367, 1911.
A New Subspecies of Zea Mays. Am. Nat., 47: 616-622, 1912.
GuiGNARD, L.: La double fecondation dans le mais. Jour. Bot. (Paris),

15: 37-50, 1901.
Harshberger, J. W.: Maize: A Botanical and Economic Study. Contrib.
Bot, Lab. Univ. Pa., i : 75-202, 1893.
Fertile Crosses of Teosinite and Maize. Gard. and Forest, 9: 522-523,

1896.
A Study of the Fertile Hybrids Produced by Crossing Teosinte and Maize.
Contrib. Bot. Lab. Pa., 2, 190T.
Hopkins, C. G., Smith, L. H., and East, E. M.: The Structure of the Corn
Kernel and the Composition of its Different Parts. 111. Agr. Exp. Sta.
Bull. 87: 77-112, 1903.
Hus, H., and Murdock, A. W.: Inheritance of Fasciation in Zea Mays.

Plant World, 14: 88-96, 1911.
Kellerman, W. a., and Swingle, W. T. : Preliminary Study of the Recep-
tivity of Corn Silk. 2d Ann. Rept. Kans. Agr. Exp. Sta., 353-355,
1890.
Bibliography of Cross-fertilization of Varieties of Corn. 2d Ann. Rept.
Kans. Agr. Exp. Sta., 346-353, 1890.

igo BOTANY OF CROP PLANTS

Experiments in Cross-fertilization of Corn, ad Ann. Rapt. 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., 1910.
Stewart, Alban: The Pistillate Spikelet in Zea Mays. Science, n.s. 42:

694, 1915.
STtTRTEVANT, E. L.: Notcs on Maize. Torrey Bot. Bull. 21: 319-343) 1894.
Varieties of Corn. U. S. Dept. Agr. Office Expt. Stats. Bull. 5/: 1-103,
1899.
Weatherwax, Paul: Morphology of the Flowers of Zea Mays. Bull,

Torrey Bot. Club, 43: 127-144, 1916.
Webber, H. J.: Xenia, or the Immediate Effect of Pollen in Maize. U. S.
Dept. Agr. Div. Veg. Path, and Veg. Phys., 22: 1-44, 19°°-

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

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.

horn\/ enSosperm

Zndglui

embr\}(/\J "
j/yfe branch^

■sienle

Fig. 70. — Sorghum (Andropogon sorghum). A, pair of spikelets; B, grain in
section; C, grain, external. X 5-

Fertile Spikelet (Fig. 71). — The sessile spikelet has thick,
leathery glumes of about equal length. The outer one par-
tially wraps about the inner. The latter is narrower and
more gradually tapering at the tip. Within the two glumes
of this sessile spikelet, are two flowers; the lower sterile, the
upper with both stamens and pistil. The so-called "third
glume" of some descriptions is the lemma of the lower, sterile
flower. Moreover, it is the only remnant of this flower. It

ANDROPOGON SORGHUM

193

encloses the parts of the fertile flower. The lemma of the
fertile flower is broad, hairy, and two-cleft at the tip; there
arises in the cleft, as a rule, a long awn which projects from
the spikelet. The awn may be very short or only represented
by a bristle. The palet is frequently absent; when pres-

lemma of sterile jlower-

aniher

Fig. 71.

—ovar\j
lemma of fertile jlower-

-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

194 BOTANY OF CROP PLANTS

Staminate Spikelet. — The stalked spikelet is narrower, and
more pointed than the fertile one. It is two-flowered. It is
subtended by two leathery glumes. Immediately within
this pair is the lemma of the sterile flower of the spikelet.
Then comes the lemma of the staminate flower; it may be
short-awned or awnless; the palet of this flower is'^absent.
The lodicules and stamens resemble those of the fertile spike-
let. There is no pistil.

Opening of Flowers and Pollination. — Flowers do not be-
gin to open on the inflorescence until the latter is entirely out
of the leaf sheath. The first flowers to open are those near
the tip of the head. Blooming proceeds from the tip down-
ward. As a rule, flowers at the tip of an inflorescence have
shed their pollen, and closed, when the lower flowers of the
head are just beginning to bloom. Flowers on branches be-
longing to one whorl are usually in about the same stage of
blooming. In nearly all cases, the sessile spikelet of a pair is
the first to open. The stalked spikelets may sometimes fail to
protrude their stamens. Most of the flowers open in the early
morning; there is but very slight amount of blooming during
the day. The stigmas may protrude to a shght 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-

ANBROPOGON SORGHUM

195

shedding anthers may be in contact at time of opening, and
since the stigma is receptive at this time, some self-poHination
must take place. Pollination between flowers of the same

Fig. 72. — Four stages in the opening of the spikelet of sorghum (Andropogon
sorghum). X 5-

plant is very common. The upper flowers are shedding pol-
len in abundance, as the receptive stigmas of lower flowers are
opening. And, in the light breeze of the morning, the head is

196 BOTANY OF CROP PLANTS

moved enough to shake pollen out. Cross-polHnation is also
very common. Individual flowers do not, as a rule, remain
open longer than the evening of the day they open. The
brown and withered stamens and stigmas commonly protrude
from between the closed glumes.

The different types of sorghum cross readily.

Fruit. — The mature grain may be entirely or in part en-
closed by the "glumes." It is oval, a Httle longer than broad,
smooth, and tipped with the remains of two style branches.
The position of the embryo is seen at the base of the grain on
one of the flat surfaces. The point of attachment — an oval,
brown area— is found at the base of the grain on the other
flat surface.

The seed is flattened in the durras, pyriform in some of the
sorgos, and globular in kafir, kowliang, and shallu.

In some types of sorghum, the pericarp bears starch. The
aleurone layer consists of one row of small cells. The starchy
endosperm is mealy within and more or less horny without.

Varieties. — The sorghums are divided into two main di-
visions: (i) saccharine or sweet sorghums, and (2) non-sac-
charine sorghums. Saccharine sorghums are tall, leafy, and
have an abundance of sweet juice, and a light crop of seed.
The chief varieties are Amber, Orange, and Sumac. Non-
saccharine sorghums are more stocky, as a rule, contain less
juice, and have a heavy crop of seed. Non-saccharine
sorghums are divided into three groups; (i) kafir group, in-
cluding those with erect, long cylindrical heads full of
obovate seeds (kafirs, white milo, etc.); (2) durra group,
including those with thick, compact, ovate, pendant inflo-
rescences, and large, flattened seeds (yellow milo, durra,
feterita) ; and (3) hroom corn group, in which the heads are
loose and spreading. Frequently the heads are on recurved
stems, called "goose necks."

ANDROPOGON SORGHUM T97

Kky to the Principal Groups of Sorguumi

['ilh juicy.
Juice abundant and very sweet.

Internodes elongated; sheaths scarcely overlapping; leaves 12 to 15 (ex-
cept in .\mber 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 Corn.
Panicle 2.5 to 4 decimeters long; rachis more than two-thirds as long
as the panicle.
Panicle conical, the branches strongly drooping; glumes at maturity

spreading and involute; seeds white or somewhat buff, Sliallii.
Panicle oval or obovate, the branches spreading; glumes at maturity
apprcssed, not involute; seeds white, brown, or reddish, Ko7diaiifi.
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, Kouiiang.
Spikelets broadly obovate, 4.5 to 6 millimeters wide.

Glumes gray or greenish, not wrinkled; densely puliescent; lemmas

awned or awnless; seeds strongly llattened, Diirra.
Glumes deep brown or black, trans\ersely wrinkled; thinly pubescent;
lemmas awned; seeds slightly flattened, Milo.

Origin of Sorghums. — The wild form from which our culti-
\at(.'tl sorghums have been derived is Andropogon halcpensis
(Johnson grass) . This species is native to tropical and sub-
tropical parts of the Old World. The view is now quite
^ Taken from Ball.

1 98

BOTANY OF CROP PLANTS

ANDROPOGON SORGHUM I99

generally adopted that the present-day cultivated sorghums
can be divided into two groups, each of which had an
independent origin in Asia and Africa respectively.

Environmental Relations. — Sorghums are of tropical
origin, and are more at home in regions with warm, sunshiny
summers. The plant will undergo high temperatures. It
is sensitive to low temperatures, and consequently cannot be
planted as early in the season as the other small cereals.

The sorghums are either able to resist or to escape drought.
For this reason they have become one of the principal crops
on the non-irrigated lands of the West. Their resistance to
drought is due largely to their low water requirement, along
with their ability to roll the leaves with approaching dry
periods, and thus reduce the water-losing surface, and also
to their ability to remain alive during a period of drought and
quickly resume growth when moisture is available. In this
last respect the sorghums differ from corn, for corn is unable
to remain in a dormant state for 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,

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) to be
harvested by pulling. After threshing the grain from the
heads, they are cured in sheds or out of doors in ricks. They
are then graded and baled, and either stored or shipped
directly to the broom factory. The "straws" of a broom
are the rachises of the sorghum inflorescence. Oklahoma,
Kansas, and Texas, in the order named, are the leading
broom-corn States.

References

Ball, CARLEibN 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: I-I4) 1910.
The History and Distribution of Sorghum. U. S. Dept. Agr. Bur. Plant

Ind. Bull. 175: 1-63, 1910.
Better Grain-sorghum Crops. U. S. Dept. Agr. Farmers' Bull. 448:

1-36, 1911-
The Importance and Improvement of the Grain Sorghums. U. S. Dept.

Agr. Bur. Plant Ind: Bull. 203: 1-45, 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: 115-126, 1885.
Piper, C. V.: The Prototype of the Cultivated Sorghums. Jour. Am. Soc.

Agron., 7: 109-117, 1915.

ANDROPOGON SORGHUM 201

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: i-i6, 1916.
Warburton, C. W.: The Non saccharine Sorghums. U. S. Dept. Agr.

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

CHAPTER XVI
ORYZA SATIVA (Rice)

Habit, Roots, Stems, Leaves. — Common cultivated
rice is an annual plant, which grows best under swampy
or very moist conditions. There are upland varieties pro-
duced with irrigation, but the lowland type is the sort
almost entirely grown in the United States. The seedHng
has one seed root. The root system is fibrous; the first,
second, and third nodes give rise to adventitious roots.
The first whorl of permanent roots is close to ^^ inch above
the lower end of the culm. It is more shallow in very moist
ground than in dry soil. The plant tillers freely, sending up
usually four or five hollow stems to a height of 2 to 6 feet.
The leaf sheaths are open, and the blades are from 8 to 12
inches long and % to i inch wide. The ligule is long, acute
or obtuse, and easily splits into two parts. It is much shorter
and more rounded on the upper leaves than on the lower.
The auricle is white or green, cartilaginous or membranous,
and hairy.

Inflorescence and Spikelet. — The inflorescence is a pan-
icle (Fig. 74). Its branches are either single or in pairs.
The spikelet " (Fig. 75) is compressed laterally. It is one-
flowered. There are two small scale-like or bristle-like
glumes, underneath each of which is a very minute, rudi-
mentary glume. The lemma is compressed, parchment-like
and five-nerved. The palet is similar to the lemma in size
and texture, but is only three-nerved. Both may be awned
or awnless. The broadly oval lodicules are small, thick, and

ORYZA SATR'A

203

fleshy. Rice dilTcrs markedly from the other common cereals
in having six well-developed and functioning stamens. The
ovary is somewhat longer than broad, smooth, and bears two

Fig. 74. — Panicle of rice (Oryza sativa).

styles, and sometimes a short, rudimentary third one. These
three are sometimes grown together at the base.
Pollination and Fertilization.— Rice is normally self-polli-

?04

BOTANY OF CROP PLANTS

nated. The flowers at the tip of the inflorescence are the flrst

to open.

--H-'M- lemma

Flower opening continues throughout the clay.
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 arc grains that appear dull; in such, the
endosperm is starchy on the outside and horny
within, (rrains with dull areas here and there
are not uncommon. An interesting rice is
Oryza glulinosa, the grains of which always
appear dull. A cut surface of this rice is de-
scribed 'as j)arairin-iike in aj)pearance. The
starch grains behave c^uite dilYerently 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).
c. embryo.

ORYZA SATIVA 20S

When it is cooked, there is formed a mass the particles of
which stick closely together; the single grains do not remain
separate. There are rices with grains pale green in color,
reddish-brown, dark brown, and white with red or dark
stripes.

In cross-section of the rice grain, the layers are very similar
to those in wheat. There is the pericarp of several layers, the
testa, the nucellus (perisperm), and the aleurone layer, usu-
ally of one row of cells. The embryo is about one-third
the length of the fruit. During the milling process, the
lemma and palet, the embryo, pericarp, testa, nucellus, and in
many cases all or a portion of the aleurone layer are removed.
This "scouring process," in the case of Honduras and Japan
rices, removes about 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 "pearHng cone" where they are scoured. This
is followed by a thorough poHshing between pieces of pigskin.
The grains then receive a coating of glucose and talc, and are
ready to be graded and packed for the market.

2o6 BOTANY OF CROP PLANTS

Beriberi. — ^This is a disease resulting from a diet consisting chiefly of
polished rice. Asiatic laborers who have been fed upon polished rice develop
this disease, while, if the rice is not polished, the disease does not appear.
When rice is polished, there is removed a large proportion of the phosphates of
the grain, and hence, when rice is almost the sole food, there is a deficiency
of phosphates in the ration, which lack results in the disease, beriberi. Of
course, those who have a mixed diet get the requisite amoimt of phosphates
from a number of different foods, and hence may eat polished rice without any
lU 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),
(fl) utilissima.

1. communis (large-kerneled rice).

2. minuta (small-kerneled rice).
(b) glutinosa (glutinous rice).

American varieties are comparatively few in number.
Three main types are grown: Honduras, Carolina and Japan.
The hulls of Honduras and Japan rice are yellowish-brown,
those of CaroHna 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_^0. sativa is the warm parts ofAsia and Africa. Culti-
vated rice probably originated in eastern Asia.

In this country, there are two quite common native
plants termed "rice." These are, Canada rice {Zizania

ORYZA SATIVA

207

aquatica), and wild rice {Zizania miliacea). Both are^.tall
aquatic grasses belonging to the same tribe (Oryzeae) as
cultivated rice. Both species of Zizania dilTer 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 neighlioring
islands. The consumption- of rice per capita in the United

Fig. 77. — I-L^r>v„w.,, .... ... Ar / nluils of C-Oi^rafhy.

Second Hook. Copyright 1916. by Albert I'crry BriKkum and Cluirlfs T.
McFarlane. American Book Company, Publishers.)

States is steadily increasing. Orientals do not polish their
rice, while all the rice that comes on the market in this coun-
try has had the hull removed, and has been polished. Rice
hulls and rice flour or polish, removed in the miUing process,
are used as stock food. Rice straw is also used as a food for
stock, and in the manufacture of paper, straw hats, straw-
board, etc. In Japan, a drink called "sake," similar to
beer, is made from rice.

208

BOTANY OF CROP PLANTS

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

te «5
o ■»;

2 S
Ok,

tJU

5fq

3 ^

■^ r: ^
2 '^ ^

O - .'■^

I. MO,
00 ^- .

ture is lower than 77°F. It reaches its best development in
moist regions. Certain sorts of upland rice are planted,
cultivated and harvested like oats. But, most of the rice

ORYZA SATIVA 209

is raised on low delta- or alluvial lands that will permit of
inundation. In lowland rice culture, flooding of the field
is usually resorted to in order to hasten germination; after
the plants have attained a height of several 'inches, from
3 to 6 inches of water are turned on to the field and kept
there continuously for twenty, thirty, or more, days, de-
pending upon the region. The water is renewed occasionally
to prevent it from becoming stagnant. It is drained off
just prior to the ripening of the grain.

The Production of Rice. — British India produced 62,-
638,912,000 pounds of rice in 1 914. During the same period,
Japaii 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
Akemine, 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, 191 2.
14

CHAPTER XVII
MILLET

The term millet does not refer to a . definite botanical
group (species, genus, or tribe) of plants. Originally it
applied to certain species of grasses belonging to the genera
ChcBtochloa (Seiaria), 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 foHage, 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 human 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. frumentacea (Japanese barnyard
millet).
Inflorescence a drooping panicle; empty glumes not awned, Panicum
miliaceum (proso or broom-corn millet).

'After Frear. 210

MILLET 211

Inflorescence spic;ite; involucre of bristles below each spikelet.

Grain enclosed in lemma and palet (the hull) at maturity; spike loose,
Chcclochloa (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. ilalica (foxtail millets).
Grain globose, forcing open the hull as it matures, and falling free when
tlireshed; spike dense, Pcnniselum glancum (pearl millet).

PENNISETUM GLAUCUM (Pearl MUlet)

Stem. — The plant.s are erect, and from 3 to 8 feet tall.
11ie culms are cylindrical and pithy; the upper internodes are
smooth, the upper nodes either smooth or short-hairy.

Leaf. — The leaf sheaths are open and hairy; the ligule is
short and fimbriated ; the leaf blade is lanceolate, long-pointed,
and long-hairy especially on the upper side.

Inflorescence. — This is a close cylindrical spike (Fig. 79),
6 to 14 inches long and -^i 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 Kmg, and truncate; the inner glume is longer, about
one-half the length of the spikelet, oval, and three- to four-
nerved. Each spikelet has two flowers, the lower stami-
nate, the upper perfect. The lemma of tiie lower staminate
llower is oval, and three- to four-nerved; the palet is small,
sometimes entirely lacking, the stamens three in number, and
lodicules absent. The staminate fiower 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, si)ikelets contain two
I)erfect flowers. The Icinnia of the fertile flower is oval,

212 BOTANY OF CROP PLANTS

pointed, and five- to six-nerved; the palet is oval, rounded
above, pointed, and thin-membranous; lodicules are absent;
there are three stamens; the ovary is obovate, smooth, and
with two style branches.

Pollination. — Pearl millet is regularly cross-pollinated.
The llowers near the middle of the intlorescence are the first

Fk;. 79. — Millets, i, Common; 2, Hungarian; 3, Siberian; 4, Cmldcn Win-
der; 5, Japanese Barnyard; 6, German; 7, Pearl.

to open. The stigmas of perfect llowers first appear be-
tween the closed glumes, then the stamens, which are in turn
followed by the appearance of staminate flowers.

Mature Grain. — The kernel is 3 to 4 millimeters long, reach-
ing the length of the glumes, obovate, somewhat iiattened on

MILLET

213

the sides, and smooth. One layer of aleurone cells is present.
The kernel is easily separated, as a rule, from the lemma and
palet.

Varieties. — ^There is considerable variation in length and
thickness of the inflorescence, color of inflorescence, and color
of grain. No varietal classirtcation
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 miflet, some of which are cat-
tail millet, African millet, Indian
millet, Egyptian miflet, 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-
limes decumbent at the base, and
often reach a height of 3 to 2,}4 feet.
Branches frequently arise from the basal nodes, and they
may hear inflorescences. The culms are cylindrical, and
rough-hairy or smooth below the nodes.

Leaf (Fig. 80). — The leaf sheaths are ()j)en. They are
co\'ered with very small pn^tuberances (papillte) 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

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. 81. — Inlloresccncc of proso millet (Panicum miliaceum).

what angled and rough with short hairs that point forwards.
In some varieties, the branches of the panicle spread to all
sides, in others they are more or less compressed and one-
sided, while in a few varieties, the panicle is much compressed,
thick, and erect.

MILLET 215

Spikelet and Flower. — The spikelets are oval in shape and
4^^ to 5 mm. long. The lowermost glume is broad, pointed,
five- to seven-nerved, and about one-half the length of the
spikelet; the second glume is the length of the spikelet and
bears 13 nerves. Within the second (longer) glume is the
lemma of a sterile flower; this lemma is slightly shorter than
the glume surrounding it, and encloses a very small palet.
Above this sterile flower, is a perfect one. The lemma of this
is parchment-like, broad, and seven-nerved; it encloses the
three-nerved palet. The two lodicules are fleshy, smooth,
and somewhat broader than long. Stamens are three in
number. There are two plumose style branches.

Pollination. — This millet is quite regularly cross-polli-
nated; however, self-pollination is not excluded.

Mature Grain. — The kernel is firmly surrounded by the
indurated, shining lemma and palet. The whole grain
measures about 3 millimeters in length and 2 millimeters
in width. The kernel itself is broadly oval, smooth, white,
and does not possess a groove or furrow as does wheat. The
position of the embryo is indicated by a shallow broad
marking about one-half the length of the kernel. The
wall of the kernel is thin. There is one row of small, flat
aleurone cells surrounding the starchy endosperm.

Varieties. — Koernicke recognizes three main types of
broom-corn millet. These are as follows:

1. Panicum miliaceum efusum. — Panicle broad, the
branches spreading to all sides.

2. Panicum miliaceum contractum. — Panicle less spread-
ing than preceding, one-sided.

3. Panicum miliaceum compacium. — Panicle compact,
thick, and erect.

Origin. — The native home of Panicum miliaceum is not

2l6

BOTANY OF CROP PLANTS

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

CH^TOCHLOA ITALICA (Foxtail 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. 1

Ijt glume
bristles

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

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 sHghtly 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

glume sterile flower

'jeriilejh

ower

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.

Pollination. — Cross-pollination is the rule; self-pollination
occasionally occurs.

Mature Grain (Fig. 84) . — The lemma and palet enclosie
the mature kernel. The grain is oval, shining, 2 to 2}^ milli-
meters long and i>^ to i^ millimeters wide. The kernel is
broad-oval, smooth, and white; it does not have a groove or
furrow. The position of the embryo is indicated by a mark

2l8

BOTANY OF CROP PLANTS

which is about one-half the length of the kernel. The peri-
carp is thin. There is a single row of small, flat cells in the
aleurone layer.

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 (Chsetochloa italica) with lemma and
palet attached; B, grain of same, embryo side with "hull" removed; C, grain
of same, side opposite the embryo; D and E, grains of pearl millet (Pennisetum
spicatum). X 10.

I. Chcetochloa italica maximum. — Heads long, open,
and drooping. This group has two subdivisions: (i)
varieties with short bristles, and (2) varieties with long
bristles. Here would be included Aino millet, German mil-
let, Golden Wonder millet, and Siberian millet.

MILLET 219

2. Chcetochloa 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) 1

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. Chcetochloa 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, ^ 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.

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.

ECmNOCHLOA FRUMENTACEA (Japanese Barnyard MiUet)

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).

Environmental Relations. — The millets require environ-
mental conditions similar to those favoring sorghums. They
are sensitive to cold, and hence must be planted after all
danger from frost is over. The water requirement of millets,
as a group, is less than that of sorghums. Hence they are
among our most drought-resistant crops, and on this account,
have been cultivated extensively on the Great Plains, from
Kansas to Dakota.

Uses of Millets. — The millets are grown as a hay crop, for
pasturage purposes, and for the seeds, which are most
commonly fed to poultry. Millet is a quick-growing crop,

MILLET 221

and is ready to cut for hay in from six to ten weeks after seed-
ing. The foxtail millets are more valuable for hay than the
proso group. The latter is most frequently grown for the
grain.

References

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

CHAPTER XVIII

PHLEUM PRATENSE (Timothy)

Description.^ — Common timothy is a perennial grass, from
iM to 5 feet high. Corms or bulbs form in the lower leaf
axils, a single seedhng sometimes having from eight to twenty.
These bulbs develop in the fall of the year, Uve through the
winter, and send up new shoots the following season. Thus
we see that the plant reproduces vegetatively as well as by
seeds. In cultivation the plant shows marked variation in
stem, leaf, and inflorescence characters, in earhness, duration
of bloom, longevity, vigor, stoohng 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 shghtly 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 than the glumes, thin, truncatCj
and finely toothed at the apex; the palet is narrow and thin.
Stamens are three in number. There are two distinct styles
with plumose stigmas. The whole process of blooming and
dehiscence of anthers takes place in about one and one-half
hours. Clark observed that the average number of days the
individual heads remain in bloom varies from seven to ten.
The upper third of the head blooms first. The time of bloom-
ing is just before daybreak. The egg-shaped grain is enclosed

PHLEUM PRATENSE

223

by the lemma and 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 timotliy {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-

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.

References

Clark, Charles F.: Variation and Correlation in Timothy. Cornell Agr.

Exp. Sta. Bull. 279: 1-350, J910.
Observations on the Blooming of Timothy. Plant World, 14: 131-136,

1911.
Webber, H. J.: The Production of New and Improved Varieties of Timothy

U. S. Dept. Agr. Bur. Plant Ind. Bull. 313: 339-381, 1912.

CHAPTER XIX
SACCHARUM OFFICINARUM (Sugar Cane)

Habit, Roots. — Sugar cane is a tall, perennial plant, re-
sembling corn and the sorghums in general habit. The root
system is hbrous and rather shallow.

Stems. — The stem is of the usual grass type — divided
into a number of joints. The cylindrical, solid culm is
8 to 15 feet high, and i to 2 inches in diameter. There are
sometimes as many as 60 to 80 nodes. The jointed stem is
prolonged into the ground, and the roots arise from the lower-
most nodes. This stem arises from the rootstock of the pre-
vious year, or, under artificial conditions, from the planted
portion of a cane. The buds are found, as usual, in the leaf
axils. They are better developed in the lower leaf axils
than in the upper. Around the culm, at the bud, are several
rows of dots; roots arise from these dots when the cane is
planted, or when in any way it is brought into contact
with the soil. Sugar cane "suckers" readily. The plant is
propagated entirely from stems. The whole stalk may be
used or only the lower parts of the stools, the so-called
''rattoons."

Leaves. — There is a single, broad, clasping leaf at each
node.

Inflorescence, Flowers, Fruit.- 'J he 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
15 225

226

BOTANY OF CROP PLANTS

spikelet. Each spikelct is two-flowered; the lower one is
sterile and consists of a palet; the upper is fertile and has
a lemma and palet, two minute lodicules, one to three sta-
mens, and a single ovary with two stigmas. There is a tuft
of long, silky hairs at the base of each spikelet. The grain

Fig. 86. — Mill where sugar cane is crushed. (From Essentials of Geography _
Second Book. Copyright, 1916. by Albert Perry Brigham and Charles T
McFarlane. American Book Company, Publishers.)

is small, silky, and of low vitaUty. Mature grains are seldom
produced in cultivated plants and pollen is often infertile.
Geographical.^ — Saccharum officinarum is a native of the
tropics. It is now grown as a crop throughout our Southern
States and in many other warm regions. It is not a success

SACCHARUM OFFICINARUM 227

north of the latitude of 33°. The roots are unable to stand
a temperature much lower than i5°F.

Sugar from Sugar Cane. — The canes, stripped of their
leaves, are first shredded by revolving spiked cylinders, and
then passed between three different sets of rollers, which
crush out the juice. About 75 per cent, of the juice is pressed
out by the first set of rollers. Between the first and second
set of rollers, the canes are sprayed with the heated juice from
the third set. About 10 per cent, of the total amount of
juice is removed by the second set of rollers. Before reach-
ing the last set of rollers, the crushed material is sprayed with
hot water; in this process about 5 per cent, of the total juice
is removed. The crushed canes, known as "bagasse,"
are utiHzed as a fuel to run the mill.

The juice that flows from the rollers is turbid, due to
the impurities which it contains. It is strained, and then
milk of Hme is added. The Hmed 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 under the control of the one
who has the crystallizing pans in charge. A high temper-
ature in the vacuum pans favors the formation of hard-
grained sugar; while a low temperature and high vacuum
produce a "soft sugar." The mixture of molasses and sugar
crystals is termed "massecuite." They are separated by
centrifugal action. The sugar crystals are then dried, and
packed for shipment.

By-products of Manufacture. — Cane molasses from the
manufacture of white and high-grade yellow sugars is used for

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 has been made of the fact that the stalks from
which the juice has been removed are used as a fuel to run
the mill. The refuse that accumulates in the purification
process is used as a fertihzer. 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 61 2,000

Philippine Islands 408,000

Australia and Fiji 407,000

Porto Rico 364,000

Argentina 304,000

United States 301,000

Mauritius 275,000

CHAPTER XX
LILIACEiE (Lily Family)

Representatives of the lily family are found all over the
world, although the family is best developed in drier parts of
the temperate zone. The family is by no means of as great
economic importance as the grass family. A number of
representatives are cultivated as vegetables, the principal
ones being onions, and asparagus. Yucca, lily (Lilium),
hyacinth and tuHp 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
Draccena, however, are shrubs or small trees. In herbace-
ous forms, the roots axe mostly fibrous and shallow, sometimes
fleshy and extending to considerable depths in the soil.

Stems. — Both underground and aerial stems are borne.
Underground stems in the family are either rhizomes or
bulbs. The character of rhizomes has been described (page
29). Bulhs are fleshy stems with a very short, usually con-
ical stem upon which are many fleshy, overlapping leaves
(Fig. 14). Bulbs, Hke rootstocks or rhizomes, are storage
organs. They are made use of in vegetative propagation.
The aerial stems may be leafy or free of leaves for a long dis-
tance. In Yucca — the soapweed or Spanish bayonet — of
the semi-arid sections of the country, the base of the aerial
stem is persistent from year to year.

Leaves. — The leaves are mostly linear, seldom divided or
toothed, and not divided into petiole and blade.
229

230

BOTANY OF CROP PLANTS

Inflorescence and Flowers.- — There are a number of
different types of inflorescences in the family. The flowers
are often single or solitary, as in the Hlies; 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 8 7) . The stamens are attached
to the receptacle or to the perianth.
The anthers are usually large and con-
spicuous. The superior ovary is
three-celled, has one style and a
three-lobed stigma.
Fruit and Seeds. — The fruit is a capsule or berry. The
capsule is a dry, splitting (dehiscent) fruit with several united
carpels. When the carpels split down the middle line as
they do in lilies, the dehiscence is said to be loculicidal.
It is distinguished from septicidal dehiscence of capsules,
in which the carpels open along the Hne of their union, as in
rhododendron, and from poricidal dehiscence in which the
carpels open by pores, as in the poppy. The herry is a fleshy
fruit possessing several to many seeds which are more or
less imbedded in the fleshy ovary wall (pericarp).

The seeds always possess abundant endosperm, which en-
closes the embryo. Considerable quantities of oil occur in
the endosperm.

Fig. 87

Flower of onion
(Allium cepa).

LILIACEiE

231

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

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

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

232 BOTANY OF CROP PLANTS

Roots. — The root system is fibrous and very shallow (Fig.
88). The roots arise from the reduced stem, forming a
fibrous tuft.

Steins. — With but few exceptions, species of the genus
Allium bear bulbs. In chives {Allium schosnoprasum) , 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 {A Ilium cepa) ,
they are large and well developed. Examination of the
mature bulb of the common onion shows it to be made up of
the much thickened bases of leaves, attached to a compara-
tively small, conical stem (Fig. 14). This is best seen in a
median, longitudinal section. From a terminal bud on this
small, underground stem, there is sent up a long hollow or
solid, leafless stem (Fig. 90) (scape) bearing an inflorescence
at the top, which in this case is an umbel. Lateral buds are

LILIACE/E

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. AU leaves are very thick and fleshy, and over-
lapping. There is no petiole.

The oldest leaves are on the

lM<; 00 —A, base of stem of common onion (Allium cepa) showmg hollow
leaves cut across; B. cross-section of hollow stem of same: C. base of stem o
leek (Allium porrum) showing flattened solid leaves; D. cross-section of solid
stem of same.

outside of the Inill). while the younger appear toward the
inside. In a longitudinal section of the bulb, it will be noted
that these younger leaves, coming from within, are higher
on the compressed stem than the older (Fig. 14)- The
edible "portion of the common onion, and of some other

234 BOTANY OF CROP PLANTS

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

spathc, consisting of two (rarely three) papery bracts. The
spathe encloses the entire umbel in the bud. The pedicels
arc long and slender.

Flower. — The flowers (Fig. 87) are regular and perfect.
The perianth consists of six distinct segments which are very
similar as to size, shape and color. The six stamens are
inserted on the bases of the perianth segments. Alternate

LILIACE^

23s

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; e, endosperm;
/, first true leaf; h, hypocotyl; j, slit from which the first true leaf emerges. A
considerably magnified. {After Bergen and Caldwell.)

single fihform style, which may be more or less indistinctly
three-cleft at the apex.

Pollination. — Species of Allium are insect pollinated. The
anthers of the flower usually mature before the stigma, al-

236 BOTANY OF CROP PLANTS

though the reverse is sometimes the case. The inner circle
of stamens is the first to shed pollen.

Fruit. — This is a three-celled, membranaceous capsule
with locuHcidal dehiscence. Two seeds, black in color,
are usually borne in each locule of the capsule. The seeds
(Fig. 92) are convex on one side and almost flat on the other,
and possess a large quantity of oil. The embryo is cylin-
drical and curved.

Germination of Seed, and the Seedling. — At the beginning
of germination, the primary root is forced out by the growth
of the curved end of the embryo (Fig. 92). The curved
end of the embryo, the cotyledon, comes out of the ground
in the form of a closed loop. The tip of the cotyledon re-
mains attacked to the endosperm and seed coat. When the
soil is loose, the endosperm and seed coat may be pulled
from the ground, but in case it is compact, they remain
beneath the ground. The cotyledon absorbs nourishment
from the endosperm. When this is used up, the cotyledon
tip withers and becomes detached from the seed coat. At
the base of the cotyledon, where it joins the hypocotyl, there
early appears a longitudinal sHt; through this, the first
foliage leaf emerges. The cotyledon later disappears
entirely.

Geographical. — There are about 250 species of the genus
Allium, the majority of which occur in boreal America,
Mexico and northern Europe. A number are also found in
Abyssinia and extratropical Asia. The cultivated onions
require cool, moist weather during the early stages of their
development, but ripen better if the weather is drier.

Key to Principal Cultivated Species of Genus Allium

Leaves flat and solid (Fig. 90).

Leaves keeled, very narrow, Allium salivum (garlic).
Leaves keeled, very broad, Allium porrum (leek).

LILIACEiE

237

Leaves cylindrical and hollow (Fig. 90).

Plants forming a dense clump with very small bulbs, Allium schceno-

prasum (cive or chives).
Plants not forming dense clumps; bulbs of considerable size.
Leaves short, awl-shaped; bulbs in clusters (Fig. 88), Allium ascaloni-

cum (shallot)
Leaves long, rather broad; bulbs not in clusters.

Bulbs very distinct, generally large (Fig. 14), Allium cepa (common

onion) .
Bulbs not distinct, usually a mere swelling at base of plant (Fig. 88).
Allium fistulosum, (Welsh onion, ciboule).

ALLIUM SATIVUM (GaiUc)

Garlic is a perennial herb. The bulbs are composed of
several small, elongated, egg-shaped bulbils, called "cloves,"
all of which are enclosed by a
whitish skin .(Fig. 93). There
are often as many as ten bulbils
in a single bulb. The scape is
from I to 2 feet high, round,
and possesses alternate, broad-
linear, sohd, flat leaves. The
spherical umbels bear many
bulblets among the small, long-
stemmed flowers. Seeds and
bulblets are borne in the same
head. In propagation, the bulb-
lets in the flower head and the
Fig. 93.— Bulb of garlic (Allium cloves are used more commonly

sativum). X M- , ,

than seeds.
GarHc is a native of southern Europe. Both the cloves
and leaves are used in seasoning salads and soups, and the
stems are also often an ingredient of sausage and other ground
meats.

238 BOTANY or 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 the same as aspara-
gus or as common onions. The leaves are used to season
soups, salads and stews.

Important varieties are Large American Flag, Mussel-
burgh, Large Rouen and Monstrous Caratan.

ALLIUM SCHCENOPRASUM (Chives or Gives)

Chives (Fig. 88) are hardy perennials bearing small,
white, narrowly ovoid, clustered bulbs with membranous
coats. The scape is stout and up to 2 feet high. The leaves
are Hnear, terete, and hollow, 7 or 8 inches in length and borne
in dense tufts. The rose-colored flowers are in dense, globu-
lar umbels. Although the plant flowers profusely, it seldom
produces seeds. It is propagated by division of the tufts of
bulbs.

Chives are natives of Europe, Asia and North America.
In this country, they grow wild from New Brunswick to
Alaska, south to Maine, northern New York, Michigan,
Wyoming and Washington.

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

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

LILIACEiE 239

bulbs are borne in clusters, but unlike garlic, are not sur-
rounded by a thin membrane. The leaves are short, cylin-
drical and hollow. The compact umbels bear lilac or reddish
flowers.

Fig. 94. — Shallot (Allium ascolonicum),
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."

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, cyUndrical 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.

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, muUiplicans) .
Potato onions.

Multipliers.

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

Top onions.
Tree onions.
Egyptian onions.

Fig. 96.

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

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

242

BOTANY OF CROP PLANTS

Skin of mature bulb colored.

1. Globe onions (Southport, Yellow Globe, Southport Red Globe, Giant
Rocco, Golden Ball, Yellow Danvers).

2. Flat Onions.

(a) Bulbs deep and distinctly red (Red Wethersfield, Red Globe, Red

Bermuda).
(6) Bulbs indifferent in color, reddish or yellowish (Yellow Danvers,

Prizetaker, Strasburg).

The "multiplier" onions have compound bulbs (Fig. 97),
copper-yellow in color, with rather thick skin and mild flavor.
When large bulbs are planted, they segregate into a number
of bulbs, and each produces six to twelve stalks. The potato

Fig. 97. — Cross-section of a multiplier onion bulb. {After Bailey.)

onion is a hardy "multiplier," sometimes called EngHsh
multiplier. The principal use of the "multipHer" group is
in the production of " bunchers " for the early market. There
are both white and yellow "multipHers."

In "top," "tree," and "Egyptian" onions, clusters of bulb-
lets are produced at the top of the scape. Some primordia
develop into flowers and others into bulblets. In* some cases,
all the primordia may develop into bulblets, and again, al-
most all may develop into flowers, some of which may pro-
duce fertile seed. Bulblets may be produced in separate
clusters one above the other on the same stalk. They may

LILIACE^ 243

germinate while still attached to the inflorescence. It is not
clearly known what is the cause of bulblet formation in
the inflorescence. Egyptian onions are often called ''peren-
nial tree onions.'' They are valued for fall planting in the
North to produce early spring "bunchers." They are a hardy
type.

The types of onions grown from seed are also classified by
Goff and by Gross. In these classifications, the primary
divisions are made on the basis of bulb shape, the secondary
ones, on size and color.

Foreign and Domestic Onions.— There is a rather sharp
distinction between ''foreign" and "domestic" types of
onions. The foreign types include Bermuda, Spanish and
Itahan onions. As compared with American types, they are
larger, less hardy, the flesh is more tender and mild, but they
do not keep as well. On account of their tenderness, the
foreign types of onions do best in Florida, Texas, and south-
ern Cahfornia. Seed of the Bermuda onion is produced
successfully only in Teneriffe, one of the Canary Islands,
off the west coast of Africa. Attempts to grow seed in the
United States have given comparatively poor results. The
Prizetaker is our best example of a Spanish onion. Impor-
tant varieties of Italian onions are the B arietta, 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), Dan vers, 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

244 BOTANY OP 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, B arietta, and American
Silverskin are used for pickling. The Egyptian (perennial
tree onion) and multipliers are valued for the production
of bunchers. It is considered that the allyl sulphide in
onions stimulates the flow of digestive juices and hence
they are often recommended for those having a tendency to
constipation. Again, on account of the small amount of
starch and sugar they contain, onions are made a part of
the diet of invalids who are not allowed starchy foods.

ASPARAGUS

Generic Description. — Members of the genus Asparagus
are all perennial plants with rather fleshy roots and short
rootstocks. From the latter, arise branching aerial stems,
which are sometimes annual, as in the common edible
asparagus (A. officinalis), or perennial as in A. laricinus,
one of the ornamental asparagi. The stems are erect or
cHmbing, in some instances {A . falcatus) reaching a distance
of 25 feet or more. The small leaf -like structures along the
stem, the so-called "leaves," are in reality modified stems
(cladophylls) (Fig. 98). They may be slender, as in com-
mon asparagus, or broad, as in Smilax. They are arranged
in clusters or whorls in the axils of the true leaves. The true
leaves (Fig. 98) are scales or spines, usually very small.
They subtend the branches. The flowers are solitary, in
small umbels or racemes and arise in the axils of the scales

LILIACE^

245

or fascicles of cladophylls. Each flower is mounted on a
very slender jointed pedicel. The perianth consists of six
similar segments which are separate or slightly united at
the base. They are persistent in the fruit. Stamens are

Fig. 98. — Garden 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)

246 BOTANY or 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 cyhndrical.

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 chmbing plant used for decorative purposes
and often called "asparagus fern," and A. sprengeri, another
"asparagus fern," much used for planting in hanging baskets.
The only edible species of any consequence is Asparagus
officinalis, the common garden asparagus.

ASPARAGUS OFFICINALIS (Asparagus)

The common garden asparagus is a much-branched peren-
nial herb reaching a height of 3 to 7 feet.

Roots. — The roots (Fig. 99) are numerous and fleshy, ex-
tending horizontally in the soil to some distance, but being
confined to the surface layers. They arise both from the
sides and bottom of the thickened rootstock. Each year new
roots are produced and the older ones die and become hollow,
without becoming separated from the stem. New roots ap-
pear above the older, which accounts for the so-called
"Hfting" of the plants.

Stems. — Asparagus bears both subterranean and aerial
stems. The underground stems are rootstocks. They are
much thickened, branched, rather woody, and about long
as broad. The rootstock or " crown " makes an annual growth
of I to 3 inches. Its extension is horizontal, taking place at
one or both ends. The older portions of the rootstock gradu-
ally die. The rootstocks send up aerial shoots (Fig. 99).
These at first are thick and fleshy ("spears") and form the

LILIACE.'E

'47

edible portion ol the plant. Tin' scales borne on these llcshy
shoots arc true leaves. At lenthi^, 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 lea\es, 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.

Fii;. 99. — r.arden asparagus (Asparagus ofTicinalis). .1, young shoot or
"spear"; B. thick, fibrous roots and young shoots arising from "crown."

However, good crops ha\-e been produced two years after
seeding. The plant may ])c. [)ropagated by divison of the
root stocks, but the common method is by seeding.

Leaf. — The true leaves (Fig. 98) are minute scales sub-
tending the whorls of clado[)hylls. Thi-y flo not i)erform leaf
functions.

Flower. —The llowers are .-^mall. drot)i)ing, greenish-\-i'll(jw
and usually solitary, but sometimes in twos or more at the

248

BOTANY OF CROP PLANTS

nodes. Each flower is borne on a short, slender jointed
pedicel (Fig. ico). The perianth is campanulate (bell-
shaped), about 6 millimeters long, the segments being linear

Fig.

(JO. — Garden asparagus (.A.sparagus officinalis). Portion of pistillate
plant in fruit, on left; and of staniinate 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 —

LILIACEiE

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:

Peoduct from Fifty Plants Each, Staminate and Pistillate

Fifty staminate
plants, ounces

Fifty pistillate
plants, ounces

37
104
266
203

Second period, ten days

Third period, ten days ...

164
154

Fourth period, ten days

Total for season

610

407

This shows a gain of the staminate plants over the pistillate
plants of about 50 per cent, for the whole season, the greatest
difference being in the first period. Hence, it seems to show
that staminate plants are earlier and more productive than
pistillate ones. Fruit production makes a greater demand
for food than does the formation of stamens. It is for this
reason that staminate plants are able to produce a greater
growth of "spears" than pistillate ones.

Pollination. — Common asparagus is insect-pollinated.
The nectaries are small and concealed at the base of the
perianth. Staminate flowers are first to open.

250 BOTANY OF CROP PLANTS

Fruit. — This is a red, spherical berry (Fig. 98) with three
cells, each of which usually contains two seeds. The perianth
is persistent in the fruit. The dark, somewhat triangular
seeds run about fifty to a gram. They preserve their germi-
nating power for four or 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 delicate flavor and is quite gener-
ally considered the more desirable. Blanched asparagus has
a much thicker stalk than the green sort. It must be under-
stood that these two market types of asparagus are simply
the result of cultural methods, and may be produced from
the same variety. To produce etiolated or blanched aspara-
gus, the plants are banked or ridged up with soil just as they
appear above ground, so that they must make an additional
growth of 4 to 10 inches before they come to light. The
shoots that develop in the soil are, of course, whitish for the
reason that the green coloring matter (chlorophyll) does not
form in the absence of light.

The number of American varieties of asparagus is small.
The most common of these are Conover's Colossal,' Palmetto,
Barr's Mammoth, Eclipse and Columbian Mammoth White.

LILIACE^ 251

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

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 CaHfornia 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. Card., 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 vol. 3 (second series),

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

CHAPTER XXI
HORACE-® (Mulberry Family)

The mulberry family has about 925 species in 55 genera,
occurring in tropical and temperate regions of both hemi-
spheres. It possesses a number of plants of considerable
economic importance. Several Asiatic species of the genus
Ficus yield a sap from which rubber is made. Ficus carica
is our cultivated fig. The India rubber plant of green-
houses and in home?, is Ficus elastica. Artocarpus communis
is the well-known bread-fruit of the tropics. Toxylon
pomijerum is the osage orange, a tree whose wood is valuable
for wheels, posts and other small articles; it is also planted
for ornament. The paper mulberry {Papyrus papyrifera) ,
is a native of Asia. Its bark is of value in paper-making.
Other genera of importance are Morus (mulberry), Humulus
(hop), and Cannabis (hemp).

Description. — Members of this family are trees, shrubs,
or herbs with a milky sap. The 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-hke 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-hke, and erect or
inflexed in the bud. In the pistillate flower , the calyx consists
252

HORACES 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, Fictis (fig).
Herbs.

Erect herbs, Cannabis (hemp).

Twining herbs, Hiimuliis (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 plicaie conduplicate

Fig. ioi. — Three principal types of vernation.

leaves on one shoot may be relatively entire, while those on
another may be moderately or deeply and irregularly lobed.
Inflorescences. — The flowers appear rather early in the
season in the axils of the lower leaves. The staminate and
pistillate inflorescences may be on different branches of the
same tree (monoecious) or on different trees (dioecious).

254 BOTANY OF CROP PLANTS

The staminate inflorescences are long, cylindrical catkins.
They soon fall. The calyx of the staminate flowers is deeply
divided into four rounded lobes. The three or four stamens
are inserted at the base of the calyx, beneath the rudimentary
pistil. The filaments are thread-like, inflexed in the bud
and uncoil like a spring at the moment of anther dehiscence.
The two-celled anthers open lengthwise and shed their
pollen toward the inside of the flower (introrse dehiscence).

The pistillate inflorescences are short, dense catkins. The
flowers in these have a deeply four-lobed calyx, the two outer
lobes being the broader. All the calyx lobes are persistent,
become fleshy, and enclose the ovary in the fruit. The
sessile ovary possesses one cell, and a single style divided
almost to the base into two very slender, hairy stigmas.

Fruit. — Each ovary develops into a nutlet bearing rem-
nants of the styles at the tip and enclosed by the thickened,
juicy calyx lobes. There is a single seed within each fruit.
However, the mulberry "fruit" as commonly understood,
is not a single drupe-Uke structure, as given above, but an
aggregate of these, i.e., an entire pistillate flower cluster.
The single fruits are very much crowded together, making up
a collection, which commonly goes by the name "mulberry."

Other "Mulberries." — The so-called paper mulberry
(Papyrus papyrif era), Sinsitiyeoi 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.

MORACEiE 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 Moms 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. Morns 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 ^ to i centimeter long. The fruit is white or pinkish
in color, i to 2 centimeters long, and poor in quality.

Geographical. — The white mulberry is a native of Asia, probably of China.
It has spread throughout Europe and has also become naturalized in eastern
United States.

Types and Varieties. — ^Economic Importance. — There are
a number of types and varieties of the white . mulberry.
According to L. H. Bailey, the following are forms or off-
shoots of Morus alba: Morus alba var. tartarica (Russian mul-
berry) and Morus alba var. venosa. The Russian mulberry

256 BOTANY OF CROP PLANTS

is a very hardy, low, bushy tree with small fruit which 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 muUicaulis {M. alba var. muUicaulis) 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. muUicaulis.
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 earhest 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 muUicaulis
mania." This species was introduced into America in 1826,
and since it was thought to be the source of the renowned
Chinese silk, soon gained wide fame here. The "craze"
died down in about 1836, and since that time, there has been
little effort to grow silk in North America upon a commercial
scale.

Uses. — ^As has been said, the white mulberry is the one
upon which silkworms are raised. In the Old World the

HORACES 257

wood of the white mulberry is used for various purposes.
The roots furnish a yellow dyestuff. In western Asia the
fruit is ground into a meal for food.

MORUS NIGRA (Black Mulberry)

Description. — The black mulberry often attains a height of
40 to 60 feet and a diameter of i to 2 feet. The numerous
branches are slender, slightly hairy at first, but later become
smooth and brownish gray. The leaves are dark, dull green,
large, pointed at the apex, rounded or heart-shaped at the
base, and the teeth rather small and close together. The
st?imma,te 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), and hence has been replaced by.
the latter, especially in the north. The Black Persian
variety of the Southern States and California belongs to
this species.

Uses. — Over central and eastern Asia the black mulberry
is a common and rather valuable fruit, and large quantities
are dried. The wood is used like that of the white mulberry.
The juice of the ripe fruit has medicinal value. The fruit of
all mulberries is relished by hogs and poultry, and it is the
practice in some localities to plant mulberry trees along
fences enclosing pastures or poultry yards.
17

258 BOTANY OF CROP PLANTS '

MORUS RUBRA (Red Mulberry)

Description. — This is the largest of the mulberry trees,
reaching a height of 60 feet and a diameter of 5 to 7 feet.
The twigs are slender, dark green, with a reddish tinge, but
finally become dark brown. The leaves are large, those on
young shoots deeply lobed, and with oblique and rounded
sinuses, in the bases of which there are no teeth; they are
rounded or heart-shaped at the base, singly or doubly toothed
or three-lobed, and with a rough upper surface and a soft
lower surface. The staminate inflorescences are slender and
cylindric. The pistillate inflorescences are much shorter than
the staminate ones. The fruit is bright red, becoming nearly
black, sweet and juicy, and about i centimeter long.

Geographical. — The red mulberry is a native of North America. It
grows from Massachusetts to southern Ontario, Michigan, and southeastern
Nebraska, eastern Kansas and southward to Florida and Texas. It is most
abundant and reaches its largest size in the Central States.

Varieties and Uses. — There are a number of varieties of
the red mulberry, all of which are more hardy than those of
the black mulberry. The principal horticultural varieties
are Hicks, Johnson and Stubbs. The wood is used for posts
and fencing, but finds its greatest usefulness in the making of
shoe lasts, churns and cooperage material.

HUMULUS (Hop)
HUMULUS LUPULUS (Common Hop)

Root. — The root system of the common hop plant is large
as compared with above ground parts. This holds true in
both young and old plants. The roots extend to consider-
able depths in the soil. and also spread.horizontally in the sur-
face layers. They give rise to a fine network of small rootlets.
Older roots become covered with a reddish-brown bark.

MORACE^

259

Stems. — The common hop is a perennial, herbaceous,
climbing plant from an underground stem, a rootstock.
These rootstocks may become quite woody. They are
commonly used for propagation.
Cuttings from them readily form
numerous adventitious roots.
Hop plants send out, near the
ground line, "runners" which
extend several feet. These are
cut into pieces, possessing two or
more buds, and used for propaga-
tion. They are known in hop
culture as "roots." However,
they are stems and not true roots.

The aerial stems, commonly
known as "bines," die back to the
ground in the fall. The lower
portion of each stalk ("bine"),
below ground, does not die, but
forms an addition to the root-
stock. The above ground stems
are herbaceous, hollow and angu-
lar, and vary in color from pale
green to purplish red or green
streaked with purple. They have
a twining habit, always winding
about the support clockwise (Fig.
102) . The angle of the support de-
termines, to a degree, the manner

and rate of growth. The most rapid and uniform growth is
made, and the longest internodes produced, when the sup-
ports are. vertical, The "bines" are assisted in their climb-
ing and clinging to supports by the presence of hooked, re-

FlG.

[02. — Dextrorse twining
of hop stem.

26o BOTANY OF CROP PLANTS

trorse hairs on each of the six edges of the stems, and on the
petioles and leaf veins. The main stems bear opposite
lateral branches. These reach their greatest length near the
middle of the main stem. They bear the pistillate inflores-
cences (hops), and hence it is important that they be formed
in abundance.

Leaves. — The hop leaves are opposite, broad, palmately
veined, and three- to five-toothed (Fig. 103). In palmately
veined leaves there are several main veins which radiate
from the leaf base. The stipules are broad, those of opposite
leaves being united.

Inflorescences. — Hops are commonly dioecious, rarely
monoecious. Hermaphroditism in hops has been noted.
Some have held that injury is the cause of this abnormality.
This theory has been refuted by Stockberger as a result of a
number of experiments in which the plants were cut back,
or pruned, or the tap root removed or portions of the crown
removed. All of them failed to develop the abnormality
(hermaphroditism). Hop plants of this type arise independ-
ently of injury. They transmit the abnormality to their
progeny when propagated vegetatively. It is held that
perfect flowers appear only in pistillate inflorescences.

S laminate inflorescences (Fig. 103, B) are paniculate, and
grow from the axils of the main shoot or from the axils of
lateral ones. Pistillate inflorescences (Fig. 103, A) are spike-
like in appearance. They are the "hops" of commerce and
are often spoken of as "burrs" or "strobiles." These are
mostly borne on lateral branches from the main stem ; they
arise in the axils of the leaves.

The pistillate inflorescence has a central, hairy axis (Fig.
103, C) upon which are arranged a number of very short
lateral branches or axes. At the base of each short lateral
branch, or axis, is a pair of bract-like structures. These are in

MORACEiE

261

_ Fig. 1 03 .—Hop (Humulus lupulus) . A , portion of plant showing pistillate
inflorescences; B. staminate inflorescence; C, rachis of pistillate inflorescence
("hop").

262

BOTANY OF CROP PLANTS

reality stipules belonging to leaves which, normally, do
not develop. Each of the lateral branches bears four pis-
tillate flowers. Below each flower is a single bracteole
(small bract). Hence, examination of a single lateral axis
or branch shows it to be made up of the following parts,
from below upwards: (i) two bract-like stipules; (2) brac-

— bract-Jike

stipule

^bracteole

Fig. 104. — Hop (Humulus lupvdus). 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

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 fertiKzation, 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. mucB' larger and
a brighter yellow than those bearing rudimentary Seeds.
Furthermore, hops, not fertilized, remain in blossom longer
than those fertilized. Howard has shown that hops arti-
ficially pollinated start to grow out at once, while those not
pollinated at all begin their growth seven to ten days later.
He shows that fertilization stimulates growth, hastens
ripening, improves the color and increases the mold-resisting
power of the plant. Salmon and Amos have shown that, in
England at least, seeded hops bearing an average of 9.5
seeds per hop, contained 15 per cent, resin and produced
147 pounds of resin per acre, while seedless hops contained
17.2 per cent, of resin and produced 92 pounds of resin
per acre. It is true that there are certain disadvantages
connected with growing seeded hops. Extra space is needed
for growing staminate plants, and there is also a possi-

264

BOTANY OF CROP PLANTS

brac\eo\e

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-Hke stipules are
covered with yellow pollen-like
grains, the so-called " hop-meal "
or "lupuHn" (Fig. 105).

Each yellow grain is a cup-
shaped, multicellular, glandular
hair filled with a resinous secre-
tion. It is an outgrowth of an
epidermal cell and consists of a
short stalk and a cup of one
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, bracteole; B, immature
lupulin gland; C, same in section;
D, mature lupulin gland; E, same
in section. (B-E after Percival.)

MORACEiE 265

northern part of the continent of Europe and in Asia as far as
eastern Siberia and south to Persia; it also grows wild in
North America, across the continent westward to New
Mexico and British America. It requires a moist, cool ch-
mate to attain its best development. Oregon, California,
New York, and Washington are the leading States in the
commercial production of hops.

Closely Related Species. — Humulus japonicus, the Japa-
nese hop, is grown as an ornamental plant. It is an annual ;
its pistillate inflorescence does not enlarge into a "hop."
Along streams from Wyoming to Utah, New Mexico and
Arizona, there is a hop (Humulus lupulus neomexicanus)
which is distinguished from the Linnaean species by its more
deeply divided leaves and more sharply acuminate bracts.

Varieties. — There are a number of varieties of hops, based
upon length and color of vines, size, shape and color of hop,
shape of bracteoles and stipular bracts, aroma, lupulin con-
tent and time of ripening. In Cahfornia the chief variety is
Large Gray American. Common New York varieties are
Enghsh 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 "lupuUn,"
as follows:

1. Essential oil.

2. Non-resinous bitter principle.

3. Resins.

4. Tannin.

Hop oil is volatile and gives the hop its characteristic
aroma. The amount of essential oil in hops varies from 0.2
to 0.8 per cent. The non-resinous bitter principle of the hop

266 BOTANY OF CROP PLANTS

hop is probably the alkaloid, lupuline. Of the r esins 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 locaHties, 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-
Hn glands imparts an aroma to the beer, the non-resinous
bitter principle and the resins give to the hopped wort a shghtly
bitter taste, and the tannin probably serves to precipitate
albuminous substances. Moreover, the maHc and citric

MORACE.E 267

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

FICUS (Fig)

Habit, Roots, Stems. — Members of this genus are trees,
shrubs or woody cHmbers (Hanas) . A number of species are
parasitic on other trees. A parasite is an organism which
secures its food material from another living organism. A
complete parasite has no power of making its own food as do
those plants which possess chlorophyll. The Golden Fig
{Ficus aurea) begins life as an epiphyte ; the seed germinates
in the crevices of other trees; the aerial roots that are first
produced take root when they strike the soil, and hence be-
come trunk-like. Aerial roots may be sent down from
branches, take root and also form trunks. The banyan tree
(Ficus henghalensis) also starts its Hfe 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 Kving columned hall, consisting of a flat expanded
canopy of leaves and numerous stem-like prop roots growing
down from the boughs" (Schimper's Plant Geography).

Leaves. — The leaves are alternate, sometimes opposite,
thick, leathery and deciduous or persistent. In the
Buddhists' sacred Peepul tree {Ficus religiosa), a plant of
tropical rain forests, the leaves have a long "dripping point,"
by means of which rain water is soon drained off. The
stipules are interpetiolar and early deciduous.

Inflorescence. — The flowers occur within an enlarged,
fleshy, hollow receptacle (Fig. 106) which is commonly borne
in the axils of leaves. Staminate and pistillate flowers may
be borne in the same receptacle or in different receptacles.

268

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, itnedium 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")-

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

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
carica, the common fig of commerce.

FICUS CARICA (Common Fig)

Habit of Plant, and Stem. — The common fig is a shrub or
small tree, seldom reaching a height of more than 25 feet.
The main trunk of the tree is short. It branches rather
irregularly, forming a round head. The gray or reddish bark
is smooth and fits closely to the wood. The twigs are stout
and thick, at first somewhat hairy but later becoming smooth
and grayish-green in color. The fig is propagated mainly
from stem cuttings.

Leaves. — These are thick and leathery and from 5 to 15
centimeters long. The general outline of the leaf is usually
oval, sometimes about circular. The leaf base is truncate
or shghtly heart-shaped. There are five to seven deep lobes,
which are coarsely toothed or slightly lobed again; each lobe
is blunt at the tip. The leaves are light green, rough and
hairy on the upper side, paler and hairy on the under side;
leaf venation is prominent.

Inflorescence, and Flowers. — The numerous small flowers
Hne the inner wall of a hollow receptacle (Fig. 106), except
near the small opening ("eye") at the apex where there are
scales or small leaves.

Among the various types of Ficus carica, there are four
distinct kinds of flowers, staminate, pistillate, gall and mule.

S laminate Flowers (Fig. 107, E). — These rarely occur in
cultivated figs, being found for the most part in the wild
fig (Caprifig). They occur just below the scales in the
receptacle. Each staminate flower usually has a four-lobed

270

BOTANY OF CROP PLANTS

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

nucellus
e0^ cf <

Fig. 107. — Flowers of fig (Ficus carica). A, B and C, mule flowers; D,
long-styled pistillate flower; E, staminate flower; F, gall produced from a
short-styled gall flower; G, fig wasp escaping from a gall; H, gall flower. {A,
B, and C after Eisen; D toG after Kerner; H after Solms-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

HORACES 271

Pedro figs, the first crop of Adriatic fi_gs, 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

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 inCaprifigs.— In the wild fig (Caprifig) there
are three crops of fruit in a year. These are as follows:

First Crop (Profichi). — The figs of this crop form in the
autumn, rest over the winter and mature the following
June or July. They bear staminate and gall flowers but
no pistillate flowers. When the figs are about one-fourth
grown, female wasps enter and deposit their eggs in the
gall flowers. In about two months, the eggs hatch out, the
perfect wasps emerge and the females, covered with pollen,
come from the fig and seek other figs in which to deposit
their eggs. By this time (June and July) the second crop
of figs is about one-fourth grown.

Second Crop (Mammoni). — The fruits of this crop possess
staminate, pistillate and gall flowers. The wasps which
emerge from the figs of the first crop enter the narrow orifice
at the apex of the receptacle (second crop) , crawl down along
the inner side, first over the staminate flowers, then over
the pistillate flowers, finally reaching the gall flowers at the
base of the receptacle, in which they deposit the eggs. The
pollen on their bodies is rubbed off on the receptive stigmas,
which are elevated on the long, curved styles, and thus polli-
nation is secured. As a result, a few fully developed seeds are
found in the second crop of Caprifigs. In August or Sep-
tember the eggs, deposited in the gall flowers of the second
crop, hatch out. The mature female wasps emerge from the
receptacle, in search of other figs in which to lay their
eggs. By this time the third crop of Caprifigs is about one-
fourth grown.

Third Crop (Mamme). — The figs of this crop possess
staminate and gall, but no female flowers. When they
are about one-fourth growu in August or September,

HORACES 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 fertiUzed, the receptacle does not come to
full maturity. Hence, it has been found necessary, in
order to grow Smyrna figs, to resort to artificial fertilization.

The artificial process of fertihzation 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

274 BOTANY OF CROP PLANTS

possessing pistillate flowers (mammoni) and those without
pistillate flowers (profichi and mamme). The effects of
fertiUzation 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
fertiHzed; they cling to the tree more tightly, the ribs are
more pronounced and the branches that bear them grow
more vigorously.

As has been indicated, Smyrna figs must be caprificated
to bring about the development of the ovaries 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 CaHfornia by
the Franciscan order of Mission Fathers. From CaHfornia,
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

MORACE^ 275

taken there to prevent the trees from winter-killing; this
object is attained by growing the plant in a bush form and
covering it with several inches of soil during the winter.

Closely Related Species in the United States. In Florida,
there are two native figs {F. aurea and F. 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.

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,

MORACE.K

-/ /

(ligilatf, with Uw to eleven linear-laiueolate, i>()inte<l and
serrate leallets. Hemp is diceeious. The slam'nuilr iii-
Jlofcscciiccs (Fi,^. 1 08, A)
are in axilhir}-, narrow and
loose panicles, the pisliUalr
in erect, leafy spikes, also
axillary. The stam'nialc
flower is borne on a slender
l)editel subtended by a
bracteole; it has five dis-
tinct sepals and five short
stamens. Each pistillalr
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, hardachene.
The curved embryo is
imbedded in a tlesh\' endo-
sperm. 'i'he fruits of
hem J) an- much larger
and hea\ier when grown
in a moist habitat than
when grown in a dry
one.

hilc t\<

llciiii' (Cmn.il

irt sali\

st;iininaU- i)l;int

; B. sin

.M-. {B ,ill<-r \V

yssidlo.)

Geographical.— Tlu- niitixc lionu' of common lu mp is ci-ntral arui western
Asia. It lias spread, as a result of lullivalion, throuRliout liurope, .\sia and
America. In many places, it has escaped from cultivation and become a
rather troublesome weed.

278

BOTANY OF CROP PLANTS

Varieties. Nearly all hemp grown in this country is of
Chinese origin, 'i'he Japanese hemp is identical, or very
similar, to Chinese hemp. European varieties (Piedmont,
Neapolitan, Hungarian, and Russian), often termed Smyrna
types, dififer 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. 'J'he best Cjuality
of hemp liber comes from Italy.

Fig. 109.- Cutting hemp, Kentucky. {From Essenlials of Geography,
Second Book. Copyriglil, 1916, by Albert Perry Brighain a>id Charles T.
McFarlaiir. 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
difliculty of obtaining laborers to do the work of retting,
breaking, and preparing the liber for the market; to the lack
of development of labor-saving machinery; to the fact that
greater profits are derived from raising other crops in hemp-

HORACES 279

growing regions; and to the greater use of other 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 Maiket—Har vesting Hemp. —
In some places, hemp is still harvested by hand with a reaping
knife or hemp hook. However, in most hemp-growing dis-
tricts, sweep-rake reapers, mowing machines, or self-rake
reapers are used.

The hemp stalks, usually 8 to 14 feet long, are bound into
bundles about 10 inches in diameter, and shocked. They
are allowed to stand in the shocks for ten to fifteen days, or
until they are dry enough to be stacked.

There is an advantage in stacking hemp, in that it rets
more quickly and more uniformly than hemp that is taken
directly from the shock. Furthermore, .the stacking of
hemp improves the quality and yield of the fiber.

Retting. — This is a process in which the substances sur-
rounding the bast fibers are partially dissolved, thus allowing
the fibers to be separated from the wood ("hurd") and thin
outer bark, and from each other. This separation is due to
the decomposing action of bacteria, in fact the retting organ-
ism has been isolated and grown in pure cultures. There are
two commercial methods of retting: dew-retting and water-
retting. The former is the common method in this country.
The hemp stalks are spread out in thin, even rows on the
ground, where they are exposed to alternate freezing and
thawing, or to cool, moist weather. The process of retting is
complete when the bark separates easily from the woody

28o BOTANY 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 cyhnder 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 staminate plants are in full bloom. If cut too early,
the fibers lack strength, and if harvested too late they are
coarse and brittle.

Hemp fiber is put to a variety of uses. It is used in the
manufacture of sail cloth, yacht cordage, binder twine,
tying twine, carpet yarns, carpet thread, sacking, bagging,
rope, upholstery webbing, and belt webbing. The ravelings
of hemp rope, termed "oakum," are used for calking seams
of wooden boats and joints of iron pipe, in pumps, engines,
and other machinery. The seed of hemp is often fed to
poultry and cage-birds. Moreover, the seed contains 20 to

HORACES 281

25 per cent, of an oil, which is sometimes extracted and used
as a substitute for Unseed 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 quaHty 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.

BOTANY OF CROP PLANTS

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Chemical Properties. John Wiley & Sons, 191 1.
Myrick, H.: The Hop: Its Culture and Curing, Marketing, Manufacture.

Orange Judd Co., 1899.
Power, F. B., Tutin, F., and Rogerson, H.: The Constituents of Hops.

Jour. Chem. Soc. (London), 103: 1267-1292, 1913.
Rabak, F.: Aroma of Hops: A Study of the Volatile Oil with Relation to the

Geographical Sources of the Hops. U. S. Dept. Agr. Jour. Agr. Research,

2: 115-159, 1914.

MORACEiE 283

Salmon, E.S., and Amos, 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-
^33', 3- 23-220; 20: 953-966; 21: 22-31, 1914.

Schmidt, J.: Investigations on Hops, V. On the Aroma of Hops. Compt.
Rend. Lab. Carlsberg, 11: 149-163, 1915.

SxocioJERGER, 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.

CHAPTER XXII

POLYGONACE^ (Buckwheat Family)

Herbaceous representatives of this family are largely found
in temperate regions, tree-
like species in Anierican
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-
ception 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.

POLYGONACE.E 285

Inflorescences. — The inflorescences vary a great deal
within the family; in buckwheat they are panicled racemes,
in Polygonum spp., terminal or axillary spike-hke 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 exemphfied by the dandelion or sunflower, the flowers
are crowded on the receptacle; the stalk of each flower is
very short or entirely absent; it is an indeterminate type.

Flowers. — The flowers are small, mostly perfect, rarely
dioecious or monoecious, and radially symmetrical. In
the genus Eriogonum, the flowers are subtended by a five- to
eight- toothed involucre. The calyx consists of two to six
segments which are below the ovary and free from it; the
segments are in one or two series, often imbricated (over-
lapping), and the inner or both series are petaloid (resembling
petals). There are no petals. The stamens vary from two
to nine; in perfect flowers, they are attached near the base
of the calyx, while in staminate ones, they may be crowded
on a central disk; the filaments are fihform, mostly distinct
but sometimes united in a ring at the base, and commonly
dilated at the base; the anthers possess two cells, and are
longitudinally dehiscent. The pistil is sohtary. The su-
perior ovary is one-celled, three-angled or compressed, rarely
four-angled, and usually sessile ; the styles are most frequently
three in number, rarely two or four, and attached to the apex
of the ovary; the stigmas are capitate (head-shaped) or
tufted, and sometimes two-cleft. Within each ovary there
is a single ovule.

Fruit. — The fruit is a three-angled (rarely four-angled)
achene, about which is frequently the persistent calyx; the

286

BOTANY OF CROP PLANTS

pericarp is hard or leathery. The single seed in each fruit
assumes the shape of the pericarp; the seed coat (testa) is
membranaceous, the endosperm is abundant and mealy, and
the embryo is straight or curved.

Key to Pkincipal 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

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

well-developed root system. The rhizome is used in the
propagation of the plant. In the spring, a number of large
leaves are sent up from the underground stem, and, later in

POLYGONACE/E

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,

i.2. ^Rhubarlj ^ Rheum rhaponticuiu) plauL iu trviic.

as they require considerable food supply which should go
to the support of the roots. The leaves are large, circular
in outline, cordate at the base, and with sinuate veins
beneath; leaf petioles are semi-cylindrical and bear membran-

288

BOTANY OF CROP PLANTS

ous ocreas. 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. in) 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.

-^-V^-perj/jfen/ j/y/ej

persiMenl
cai\jx lobe

Fig.

:i3. — Fruit of rhubarb (Rheum rhaponticum).
cross-section. X 5.

.1, external view; B,

Self-pollination is prevented to a large degree by the matu-
ration of anthers before the stigmas. Stigmas of flowers
below on the inflorescence receive pollen from the anthers of
younger flowers borne above them. Pollen is disseminated
by wind, insects, and gravity.

Fruit.- Rhubarb fruit (Fig. 113) is an achene surrounded
at the base with the persistent remains of the perianth; it has
three broad, thin wings which are traversed by a longitudinal
nerve running near ihu margin; it is tip[)ed l)y a small per-

POLYGONACE/E 289

sistent style. The seeds are three-angled, conforming in
shape to the fruit; the testa is (hin and red; the hiluni and
micropyle are basal; the endosperm is abundant and sur-
rounds the large, straight embryo, (jood-sized plants can
be raised from seed in one season if it is [)lanted early. The
seedlings of rhubarb show interesting xariation.

Geographical, and Varieties -The common rhubarb is a
native of Asia. It has become introduced into many coun-
tries of the temperate cHmates. 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. rliaponlicum, R. undulatnm and
R. palmalum. The principal varieties grown are J.innocus,
Victoria and Monarch. There are a number or ornamental
species of Rheum, most of which are tlistinguished from com-
mon rhubarb by their more or less lobed leaves, the margins
of w^hich may be coarsely or linely toothed.

Uses. — Rhubarb or pie plant is a vegetable used for its
large, acid leaf stalks, which are of the best quahty early in
the season. 'J'he leaf stalks are usually made into pies or
sauce, and occasionally wine is made from the juice.

FAGOPYRUM VULGARE (Common Buckwheat)

Roots. — Common l)uckwheat 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. Tkickwheat differs from the true cereals, in
the possession of a single {)rinuir}- root, and a much less
extensive root system.

Stems. — The stems are quite succulent, smooth, except at
the nodes, and strongly groo\ed. I'>ach seed gives rise to but
one stem which may branch freely, but, unlike grasses, no
19

290

BOTANY OF CROP PLANTS

''suckers" or "tillers" are produced. The amount of
branching depends upon the thickness of seeding; the plants
branch freely when not crowded and feebly when crowded.
The young stems vary from green to red, and turn brown
with age.

c^m

Leaves.- The leaves are ahernaLely 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. 1 10), which soon falls oil.

POLYGONACE^

291

Inflorescence. — The inflorescence is a raceme .whicli 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.

nectar ^land
receptacle

Fig. 115. — Common buckwheat (Pagopyrum vulgare). A, achene; B,
floral diagram; C, cross-section of fruit; D, flower. (J5 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

292 BOTANY OF CROP PLANTS

base of the fruit. There are eight stamens with glabrous,
fihform filaments and oblong anthers. Three of the stamens
closely surround the styles and dehisce outward, while the
five others are inserted outside of these three, and dehisce
inward. The single ovary is one-celled and one-ovuled and
bears three style branches, which are bent back in fruit.

The plant begins to bloom when quite young and continues
until frost.

Dimorphism and 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. 115, A) is a triangular (some-
times two- or four-angled) crustaceous achene, brown,
streaked with black, or entirely black; the point of the
''grain" is the stigmatic end, while the opposite end shows
a fragment of the flower stalk (pedicel), and small, persistent,
withered calyx lobes which have become adherent to the peri-
carp. The "hull" is the pericarp and attached portions.

Seed. — The single seed conforms in shape to the pericarp.
There is an abundance of white, dry, floury endosperm in
which is imbedded the embryo. Buckwheat endosperm is

POLYGONACE^

293

more starchy than that of wheat, oats, barley, rye and corn,
and the fat content is lower. Consequently, buckwheat
flour is low in percentage of protein and fat. The embryo
("germ"), however, has an abundance of fat and protein, and
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.

—jtarchv
endosperm

Fig. 116. — Common buckwheat (Fagopyrum vulgare). Section of mature
seed. (After Stevens.)

Geographical.^ — Common buckwheat has been cultivated
in China for 1,000 years. It was introduced into Europe
during the middle ages. It was brought into this country
by the early settlers. It has escaped from cultivation in
North America, and is now common throughout northern
United States and Canada.

Other Species. — There are two other species of Fagopyrum,
one of which, F. tataricum, at least, has been cultivated to a
slight extent in this country, and is also an occasional escape
from cultivation. Tatary buckwheat is distinguished from
the common form by the simple racemes, its rough hull, and
the wavy fruit angles. It is cultivated where a hardy sort is

294 BOTANY or CROP PLANTS

needed. The notch-seeded buckwheat {F. emarginatum),
a form cultivated in northeastern India and China, is dis-
tinguished from the preceding by having the angles of the
smooth hull prolonged into wide, rounded wings.

Varieties. — Three varieties of common buckwheat are
grown in the United States: Japanese, silver hull, and com-
mon gray. They may be distinguished by the following
key:

Key to Varieties of Common Buckwheat

Faces of grain slightly concave; angles extended into very short wings,

Common gray.
Faces of grain flat; angles not extended into wings.

Grain small and plump, Silver hull.

Grain large and not so plump, Japanese.

Environmental Relations. — 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-

POLYGONACEiE 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: S9-66, 1912.
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.

CHAPTER XXIII
CHENOPODIACE^ (Goosefoot Family)

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

CHENOPODIACEiE 297

are usually small, greenish, and bractless (Sarcobatus, grease-
wood), or bracteolate (Beta). They are perfect {Beta), pis-
tillate (Kochia), polygamous {Kochia), monoecious (Sar-
cobatus), or dioecious {Atriplex spp.) They are usually regu-
lar. There are no petals. The calyx is three- to five-lobed
or parted, rarely of one sepal (Mowo/e/jw), or is entirely want-
ing in the pistillate flowers of some genera {Atriplex). 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 /rw^V is a utricle (one- Fig. 117.—^,
seeded fruit with a loose pericarp) with mem- sarc^obl'Tif^ b,
branous, leathery, or thin pericarp. The annular embryo
seeds may possess an abundance of endo-
sperm {Beta, Eurotia, etc.), or none {Sarcobatus, Salsola);
the embryo is spirally coiled (Fig. 117) {Salsola), annular
{Beta), or conduplicate {Salicornia).

Key to Principal Genera

Embryo spirally coiled (Fig. 117); endosperm little or none.
Shrubs, Sarcobatus (greasewood).
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).

298

BOTANY OF CROP PLANTS

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

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

SPINACIA OLERACEA (Spinach)

Description. — Spinach is an erect, smooth, annual herb.
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

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 outhne. 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

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. 118, C, D) is a
utricle consisting of a compressed seed surrounded 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 runs 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 Mountain
spinach, or or ache (A triplex hortensis). 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 summer "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
abundance 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.

300 BOTANY OF CROP PLANTS

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.

CIlENOPODIACEyE 3OI

4. Leaf beets.
(d) Chard or Swiss chard.
(b) Ornamental or foHage beets.

The Wild Beet. . Along the coast of southern Europe,
there grows a perennial sea beet (Beta marilima) 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 }car 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 abundant. 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; the.se stems give rise
to flowering branches (Fig. 119).

302 BOTANY OF CROP PLANTS

Shape and Structiire 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

'--1 . i^^*ttVi

Fig. 1 19. — Sugar beet plant in full fruit.

of httle signifuancc. I'ritchard 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 unifonniLy of tyi)c is desirable, but any aLLcni[)t
to judge of the sugar content ol an individual beet by the

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

vascular

-^mali-ceileci
parench\jma

larde-cejfed
parencmma

-ring ofgrowih

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 surrovmding 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-

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-
ing distribution of sugar in an
average sugar beet. {After
Molinari.)

Fig. 122. — Sugar beet (Beta vulgaris).

A, flowers grouped in the axil of a bract;

B, cluster of flowers which fuse to form a
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

CHENOPODIACE^

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

Fig. 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 base, 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

3o6 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
fertilization" (geitonogamy) is usu-
ally ineffective. He has also demon-
strated that thrips voluntarily travel
from plant to plant, and positively
assist in polKnation of beet flowers.
1^^ ' Bees are of little consequence in this

Fig. 124.— Diagram of process. Wind is the chief factor in
S o"7:;ef cuT °iLX beet pollen dissemination.
wise. (After Townsend and Finlt and Sccd. — The ripened

Riltue, U. S. Dept. Agri.) . , _ . . , j, ,

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

CHENOPODIACE^ 307

seeds and 'multiple-germ seeds have not been made. Of
course, the advantage of single-germ seed is in the ehmina-
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 Hes 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 which 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 ground. The seedhng consists of a very short
hypocotyl which scarcely appears above ground, two rather
fleshy, glabrous, short-petioled, one-nerved cotyledons, and

3o8

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 t3^pes of sugar beets: Kleinwanzlebener 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 types are about
the same. The tonnage of the Vilmorin is smaller.

Composition of Sugar Beets.-

made by Headden.^

-The following analyses of sugar beets were

German
beet,-
grams

Michigan

beet,
grams

Colorado
beet,
grams

Montana
beet,
grams

74-SSO
25-450
16.600
0.800
o". 706

813.000
78.000
22.000
15.300
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

Water

Dry substance

Sugar

Total ash

Protein

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 afifected 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.

CHENOPODIACE^ 309

machinery into narrow strips ("cossettes")- These strips
are placed in diffusion vessels, treated with water at a tem-
perature of about 80 to 84°C., 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 crystaUization 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 crystaUization 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 accumulates in the purification process is sometimes
employed as a fertihzer. 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
utiHzing sugar-beet molasses,

3IO BOTANY OP CROP PLANTS

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 differ from them in color, shape, and
edible quahties.

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

Fig. 125. — Percentage of the world's supply of beet sugar (raw) produced in
the different countries, campaign of 1913-14.

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 deHcate 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 OF CROP PLANTS

CHARD

The edible "leaf beets" go under various names: Spinach
beet, sea-kale beet. Swiss chard, silver beet, chard, and
Bcla cvcla. The tlower> and fruit are like those of the

E9i

Ub^^^^^^H

HIHI

^m7>j^Ej|

r "^^19

H^H

1 , ^^S

'^^

i^Si

^^B^t'^r >S

^■'Wh

^^B ^'Hb

Edf

^^' (^^^1

^^B '^'^

W '^

^^^^^H

^^^^Lv'a

Sf ^^H

Fk;. I J7. -Chard or IlmI larl (Beta vulj^ari.).

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

CHENOPODIACE^

313

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 Lucullus, 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 Hke spinach, and the petioles are served like
asparagus.

MANGEL-WURZELS OR MANGELS 1

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

-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. 128):

1. Glohe. — 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

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-Hke roots.

Composition and Uses. — I'he 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 utiHzed. 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. Kept. N. Y. Agr. Exp.

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

CHENOPODIACE^ 315

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

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

Wilhelms Inst. f. Landw. Bromberg, 4: 399-415, 1912.
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, iQ^S-

CHAPTER XXIV
GROSSULARIACE^ (Gooseberry Family)

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

GROSSULARIACE^

317

Leaves. — The leaves are alternate, palmately lobed, often
resinous-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 after 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

3l8 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.

Pollination. — 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

vdscular bundle
Of receptacle

vascular bundle

LSC

ofc

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 from 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 reaHty 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-

GROSSULARIACEiE 319

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 100 species of the genus Ribes. These arc,
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. grossularia (European
gooseberry).
Thornless and pricklel ess; 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. atireum
(Missouri, flowering, golden, or Buffalo currant).

320 BOTANY OF CROP PLANTS

CURRANTS

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

(i) Rihes rubrum {R. vulgare) 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 found
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) Rihes 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) Rihes americanum, 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) Rihes aureum is the chief American flowering currant.
It is cultivated principally as an ornamental shrub, but also

GROSSULARIACEiE 321

for its fruit. The wedge-shaped leaves are three-lobed,
smooth, and resinous when young. 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 grossularia, 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 the
common gooseberry mildew {Sphcerotheca mors-uvcB).

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

32 2 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.

CHAPTER XXV

CRUCIFER^ (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 FAirope
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. — ]\rost mus-
tards are herbaceous; a few are
woody. The sap is usually
watery and acrid. The leaves
are alternate, simple, and vari-
ously lobed or dissected. The
sti[)ules are wanting.

Inflorescence and Flowers.— The predominant t\[)e of
injloresccnce is a terminal raceme; rarely the [lowers are
solitary at the end of a scape. The mustard jloiver is char-
323

Cruciferai. Floral
diagram above; flower in median
longitudinal section below.

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-

pjf. j_j2. — Common garden radish (Raphanus sativus). In flower, on
right; and in fruit, 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

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, + fera, 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,
compound, 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-hke
fruit (Fig. 133), which is termed a silique pic. 133.— Fruit
(Brassica) when long and slender, and a of cabbage (Bras-
silicle (Bursa) when short and broad. The tata)°. ^^^^!\xter-
sides (valves) of the fruit separate at dehis- ^.^^'' ^' cross-sec-
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

326 . ■ BOTANY OP 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-Kved, 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 Ufa of the seed.

Closely Related Families. — Members of the mustard family may be mis-
taken for those of the poppy family (PapMeracece) 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).

CRUCIFERiE 327

BRASSICA

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, sihque is a short or
elongated style tipped by a truncate or two-lobed stigma.
The seeds are in one row in each cell.

Pollination.— Representatives of rtie. 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 (whit?

mustard).

328 BOTANY OF 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.).

BR/^SSICA 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-
ern 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.

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 of Cabbages

Stem of first year elongated.

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

B. oleracea var. viridis (kales and coUard).
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 Vilmorin.) oleracea gemmifera).

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

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

330 BOTANY OF CROP PLANTS

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

oleracea var. caulo-rapa (kohlrabi).
Stem not turnip-like, leafy below, inflorescence partially developing

first season (Fig. 139), B. oleracea var. botryiis (cauliflower, broccoli).

BRASSICA OLERACEA VAR. VIRIDIS (Fig. 13s)

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 collard. Collards are grown in the South par-
ticularly. This southern form is known as the Georgia
collard. 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 ground. 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 form. 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 cauHflower, kale and collard 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 main stem is elongated and
unbranched. The first "sprouts" to appear are those at the
base of the stem, subsequent ones appearing in order from

CRUCIFER^

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 oleraceacapitata). Three com-
mon types of heads: A, pointed or oblong; B, 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,

332 BOTANY OF CROP PLANTS

smooth leaves, the whole forming the "head." A longitu-
dinal section of a cabbage head shows the terminal bud, and,
in some instances, rather well-developed axillary ones.

Types. — There are numerous varieties of cabbages. They
have been grouped into a number of different types. These
types vary as to color, size, and shape of head and leaves,
texture of leaves, length of stalk, earUness, etc. As grouped
here, the types may be distinguished as follows:

Key to Types of Common Head Cabbage

Leaves smooth, not crimped or curled.
Leaves dark purple or red, Red cabbages.
Leaves glaucous-green.

Heads cone-shaped, longer than broad (Fig. 137, A), Winningstadt and

Wakefield cabbages.
Heads spherical (Fig. 137, B), Danish Ball Head cabbages.
Heads flat, broader than long (Fig. 137, C), Flat Dutch or Drumhead
cabbages.
Leaves crimped or curled, Savoy cabbages.

The red varieties of cabbage are valued for pickhng and
slaw. The Wakefields are the ones most extensively grown
in trucking districts. There are two main types of Wake-
fields: True Jersey Wakefield which has small heads pointed
at the tip, and Charleston Wakefield, with a head broader,
flatter and more obtuse-pointed. Danish Ball Head cab-
bages are most used for storage purposes. The Savoy cab-
bages, especially when sHghtly frosted, are known for their
very excellent flavor.

Uses. — Cabbage is grown as a market-garden, truck and
farm crop, and is best adapted to a cool climate. As a human
food, it is most generally boiled or used as slaw. Sauerkraut
is cabbage cut up into very fine pieces and allowed to ferment
in a brine made of its own juice with salt. The sour taste is
due to the presence of lactic acid, formed by the action of

CRUCIFER^

333

lactic-acid species of bacteria on the sugar in the cabbage
juice. Ordinarily there is a maximum of about i per cent, of
lactic acid, the presence of which prevents putrefaction of the
sauerkraut. Among other organisms, yeast is universally
present in the fermenting cabbage. Cabbages are also used
quite extensively for pickling, and as a food for stock and
chickens.

BRASSICA OLERACEA VAR. CAULO-RAPA
(Kohlrabi or Tijrnip-rooted Cabbage) (Fig, 138)

The stem is short, much thickened, fleshy, and stands out
of the ground. The fleshy part comes from the stem above
the cotyledons, hence is not
root. The swelling begins at
the ground line; there is formed
a large, spherical body upon
which are very prominent, broad
leaf scars.

As to color there are two
principal types: Those with
white "balls" or stems (White
Vienna Erfurt) ; and those with
purple "balls" (Purple Vienna) .

Kohlrabi is not grown exten-
sively in the United States. It
is used particularly by our
foreign population, being stewed
and eaten like turnips or ruta-
bagas. It is also a valuable
stock food; both the stems and
leaves are used for this purpose.
Kohlrabi is chiefly grown as an early spring crop, less frequently
as a fall crop. It does not endure the heat of summer.

Fig. 138. — Kohlrabi (Brassica
oleracea caulo-rapa).

334

BOTANY OF CROP PLANTS

BRASSICA OLERACEA VAR. BOTRYTIS
(Cauliflower, Broccoli) (Fig. 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).
portion of "head."

A, entire plant; B,

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-

CRUCIFER^ 335

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

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 a^swoUen 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 3^
inch in diameter and of the characteristic mustard type.
The fruit is 1 3^ 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 sihque.

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).

33^

BOTANY OF CROP PLANTS

The principal varieties grown in the United States may
also be classified as follows (in each division but one or two
examples are given) :

Flesh white.

Root entirely white.

Flat (Early White Flat Dutch Strap-leaved, Extra Early White Milan).
Spherical (Snowball, White Globe Strap-leaved).
Oval (White Egg).
Carrot-shaped (Cow-horn).

Fig. 140. — Types of turnips (Brassica rapa). A, flat; B, tankard or spindle;
C, globe; D, long. (After Percival.)

Root purple or red at top, white below.

Flat (Purple Top Strap-leaved, Extra Early Purple-topped MUan).

Spherical (Purple Top White Globe).
Root entirely red (Scarlet Kashmyr).
Flesh yellow.
Root entirely yeUow (Golden Ball).
Root green at top, yellow below (Amber Globe),
Root red at top, yellow below (Early Red Top Globe).

Structure and Uses. — It will be recalled that the greater
portion of a turnip is tap root. In cross-section, it shows the
following layers (Fig. 141) :

1. Outer layer or cortex (bark).

2. Cambium.

3. Main flesh of turnip (wood and pith). J

CRUCIFER^

337

In the fleshy root of the turnip, the walls of the cells which
make up the wood are not lignified, and hence the tissue is
soft, unUke ordinary wood tissue. The medullary rays are
very indistinct. Some turnips are coarse in texture and
such are used for stock food. The turnips of finer texture

'--cortex

"Z^ -rr .^\- camhwsm

Fig. 141. — Root of turnip (Brassica rapa) in cross-section. Diagrammatic.

are used as food by man. In the South the variety Seven
Top is grown as a green forage and green manure.

BRASSICA CAMPESTRIS (Rutabaga or Swede Turnip) (Fig. 142)

Description. — This species resembles very closely B. rapa,
the common turnip. Rutabagas or "Swedes," have a short
stem or "neck" at the upper part of the vegetable. It is
this character which easily distinguishes the rutabaga vege-
table from that of turnip. The flesh is solid and yellow or
orange in color. The first leaves are bluish white, and all
leaves have thick, fleshy petioles. The yellow flowers are
larger than those of the turnip, and the claws are longer.

Uses. — Rutabagas or "Swedes" have less water than com-
mon turnips. They are commonly grown as a food for
stock, but are also eaten in large quantities by man. They

338 BOTANY OP 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 young 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

CRUCIFER^ 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 soiUng 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 }4 inch or more in length. The
seeds are dark brown.

Black mustard is a native of Europe and Asia. It has
become naturahzed 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

340 BOTANY OF CROP PLANTS

the mustards from grain fields. All grasses are resistant to
injury from this spray, but the young mustards, and niany
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 (Brassicajuncea). 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 dressings 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 ground 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 Hghter colored bristly pods, and its Hghter 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

CRUCIFER^ 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 until 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 23^ 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). Th.e flowers are of the typical mus-
tard type; the sepals are erect and sac-like at the base; the
petals rose-hlac 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. — Th^ seeds are small and of a yellowish
color; on one side, when viewed with a hand lens, may be
seen a small spot, in reahty double, made up of the hilum and

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 outhne and
broadly notched at the tip.

Geographical Distribution and Origin. — The common
radish is found growing wild in the temperate regions of the
Old World. It was introduced into this country by the
earlier 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 sprung
from Raphanus raphanisirum, 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

CRUCIPER^ " 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 caiidatus, 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.

Types 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, cauHflowers 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, Chartiers,
White Strasburg, Stuttgart.

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

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").

344

BOTANY OF CROP PLANTS

Radishes vary in color: some varieties are white, others pink, red, purple,
mottled, 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; B,
globular; C, olive-shaped; D, half-long; E, long. (.After Corbetl.)

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.

CRUCIFER^ 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 Radicula 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 liome
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

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.

-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 sihques (Fig. 145) are

CRUCIFER^

347

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

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

References

Carriere, E. a.: Une nouvelle

plante fourragere at econom-

ique. Journ. d'Agric. Prat.

Annee, ^^t tome ii: 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) .

CHAPTER XXVI

ROSACEA (Rose Family)

The Rosacese are well represented m 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 (mountain 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 SpircBu,

terminal or axillary and soHtary, racemose

or paniculate in Rubus, and corjnnbose or

racemose in the strawberry. It is interest-

FiG. i46^Fiorai ing to notc the great number of different

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

{After Wossidlo.) . . , , , ^ ., . , . ,

contrast it with the mustard family, m 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

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

rece'pkcle
drupeki

ca^K lobe

■6li^ma

Fig. 147. — American red raspberry (Rubus strigosus). A, median lengthwise
section of flower, X 4; B, same of fruit, 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

350 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 Spircsa, an aggregate of
drupelets in raspberry, blackberry and dewberry, or an
aggregate of achenes in strawberry and rose. The folHcle
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 of Rosace^e

Fruit not inclosed in a hollow receptacle, i.e., the calyx not constricted over
the fruit.
Carpels becoming follicles, Spiraa.
Carpels become small 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, Potenlilla (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

ROSACE/E

351

mountain bramble). They are usually designated as
"brambles." The stems are, as a rule, prickly, erect, decum-
bent, or creeping. The stems ("canes") 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

Fig. 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 advisabiUty of removing canes once they
have borne fruit.

Propagation.^Red rasi)berrics, blackberries and dew-
berries (rarely) "sucker" readily. This natural tendency to

352 BOTANY or CROP PLANTS

send up sprouts from the roots is taken advantage of by the
fruit-raiser. All plants which reproduce naturally from
suckers arc 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
compound three- to seven-foHate, and bear persistent
stipules. In Rubus trhialis, southern dewberry, the leaves
arc evergreen.

Inflorescence. — The flowers are terminal or axillar\-, soli-
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
19 13, 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 vilifolius, the Pacific Coast
dewberry, however, there are both hermaphroditic and pistil-
late plants. Rubus Chamccmorus is flioccious. The recep-
tacle is Hat or convex. The live-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 rece[)tacle; each pistil bears a single
thread-like style. The styles arc hairy and somewhat
broadened at the base in the raspberry; while they are
narrow and free from hair at the base in the blackberry.

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 polhnation. Better yields are
secured, in the case of some dewberries, if they are planted
adjacent to another variety so that cross-fertiHzation 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, Dew-
berries.
Drupelets readily separating from the receptacle when fruit is being picked,
clinging together in form of cup, Raspberries.
23

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 in "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-clustec blackberries or black-
berry-dewberry).
Inflorescences more compact, the flowers not so scattered along the main
axis.
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. cuneifoUus (sand blackberry).
Lower surfaces of leaves pubescent but not whitish; plants i to 8 feet
tall, thorny, R. nigrobaccus v&r.sativus (short-cluster blackberries).

Rubus nigrobaccus. — 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.

ROSACE.E

355

The fruits arc small and globular or globular-oblong, and grow in smal'
clusters. Wilson and Rathbun are typical varieties.

Rubus aigutus. — The plants are erect, stiff, prickly, and with stems
stronglj' 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 I'lorida and Arkansas. Common varieties are Dorchester, Early Harvest,
and Brunton Early.

Rubus cuneifolius. — The sand blackberry is a stifT, 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.

Fu".. 149. — Xurlhcrn dewberry (Rubus villosus).
DEWBERRIES

These differ from blackberries in their trailing habit,
cymose inflorescences, and propagation by tips. They
ha\-e received tin- iianic "trailinLr black.I)err\'." There are

356 BOTANY OF CROP PLANTS

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

K.EY TO Principal Species of Dewberries

Leaves'evcrgrecn, R. Irivialis (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.

vilifolius (western dewberry).
Plants all perfect; leaflets fmely toothed, R. villostis (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, pctioled, 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.

Rubus invisus. — The stems are moderately prickly. 'J"he 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
Hartel and Afammoth.

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 Xorlhern States; it is 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 roribaccus) is a more robust form with large wedge-obovate,
jagged leaflets, and large flowers on long pedicels.

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 of Raspberries

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

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

the season, R. idaus (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-
codermis, R. glaucifolius, R. bernardinus.

Rubus idaeus. — 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. idcsus 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

358 BOTANY OF CROP PLANTS

or lobed leaflets, which are whitish-pubescent beneath. The 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 Loganberry. — 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^ 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 strigostis.

FRAGARIA (Strawberry)

Roots and Stems. — 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 "runners." Runners
are slender stems, growing along the ground surface; they
have long internodes, 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 a-re usually formed after

^ journal of Heredity, 7: 504-507, 1916.

ROSACE.E 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 ground surface..
Roots do not extend over a depth of 2 feet in the soil, and
horizontally, scarcely beyond the area covered by the leaves.
Practicallv all roots arc within the first foot of soil.

,cif .slra\v!)crry (Frai;aria cliilnoiisis). A1j'A-c. iwu i)crfcct,
ilowLTs; below two pistillate llowers.

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 tlowers are in
small racemes or corymbs on long, erect, leafless scai)es

360

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. 150); 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

stamens

\^^rim of receptacle
^jleshxj receptacle

Fig. 151. — Strawberry (Fratjaria chilueiisis). Median lengthwise section of
flower. X 4.

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

ROSACEA 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 m 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 fertili-
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") 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 reahty 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

362

BOTANY OF CROP PLANTS

withered stamens are at the base of the fruit. These con-
stitute the "hull" 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

corfex of
idle

medulla of
receptacle

Fig. 152. — Strawberry (Fragaria chiloensis). A, "frviit" in median length-
wise section, X 2>^; B, single achene, X 20.

The achenes are com-

attachment of fruit to receptacle,
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.

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 PiaNCiPAL Species of Fragaria

Leaves usually projecting above the flowers and fruit; achenes sunken in the
flesh.
Runners appearing after the fruit; berry dark; calyx large; leaves shining

above, bluish- white beneath, F. chiloensis (Chilean strawberry).

Runners appearing with the fruit; berry scarlet; calyx medium; leaves light

green on both surfaces, F. virginiana (scarlet or Virginian strawberry).

Leaves usually not projecting above the flowers and fruit; achenes not

sunken in the flesh, F. vesca (perpetual or European strawberry) .

Fragaria virginiana (Virginia or Scarlet Strawberry). — ^This is a stout, dark

364 BOTANY OF CROP PLANTS

green, tufted herb with soft-hairy leaves. The petioles are from 2 to 6 inches
long, the leaflets oval or obovate, obtuse, dentate, the lateral not symmetrical
at the base. The scape is usually shorter than the leaves, at least not exceed-
ing them, hence the fruits are borne below the leaves. The calyx lobes are
erect at maturity. The fruit is red, ovoid, and with achenes imbedded in the
flesh.

The species extends from New Brunswick to South Dakota, south to Florida,
Louisiana and Arizona.

Fragaria vesca {European Wood or Everlasting Strawberry). — ^This is a stout,
dark green, tufted plant with hairy leaves. The leaflets are ovate or broadly
oval, obtuse, dentate, the lateral not symmetrical at the base. The scape is
longer than the leaves, hence the fruits are borne above the leaves. The calyx
lobes are spreading or reflexed. The fruit is red, hemispheric or conic, with
achenes not imbedded in the flesh.

This strawberry is a native of Europe, but naturalized in the Eastern and
Middle States. It has given us our Perpetual and Ever bearing varieties.

Fragaria chiloensis (Chilean Strawberry). — The Chilean strawberry is a low
form with thick leaves, shining above and bluish-white beneath; the runners
appear after the fruit is gone. The fruit is large, firm, dark, with a large
"hull," and with achenes sunken in the flesh.

It is a native of the western coasts of South America and North America.
Most of the common varieties of strawberries belong to the Chilean species.

Varieties. — The number of varieties of strawberries is great.
They are commonly divided into three groups as to time of
maturing: first, early (Warfield, Excelsior, Bederwood);
second, medium (Ridgeway, Dunlap, Marshall, Jucunda);
and third, late (Aroma, Gandy, Chesapeake, Splendid).
Growers distinguish between commercial varieties and those
for home consumption. A good commercial variety should
be hardy, very productive, of good color, firm, and of good
size and form. Among good commercial varieties, may be
mentioned Bederwood, Excelsior, Jucunda, Dunlap, Captian
Jack, Splendid, and Parson's Beauty. Such varieties as
Warfield, Ridgeway, Marshall, Aroma, and Chesapeake are
grown for home use.

Origin of New Varieties. — Strawberries seldom come true
to seed; hience it is possible to secure new varieties by plant-

ROSACEA 365

ing seed. When a desirable variation appears, propagatejt
and keep it "true" by means of runners. This method of
vegetative propagation insures permanency in the characters
of the variety selected.

Uses. — Strawberries are used chiefly in the fresh state.
There is an increasing demand for such strawberry products
as crushed fruit, preserves, marmalades, and jellies. Large
quantities are put up fresh for use at soda fountains and in
the manufacture of ice cream.

References

Bailey, L. H.: Survival of the Unlike. Essay 25, Strawberries, The

MacMillan Co., 1896.
Blanchard, W. H.: Rubus of Eastern N. A. Bull. Torrey Bot. Club, 38:

425-439, iQii-
BuNYARD, E. A.: The History and Development of the Strawberry. Jour.

Hort. Soc, 39: 541-552, 1914-
CoRBETT, L. C: Strawberries. U S. Dept. Agr. Farmers' Bull. 198: 1-24,

1904.

CHAPTER XXVII
POMACES (Apple Family)

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

Inflorescence. — The inflorescences are racemose {Amel-
ancJner, service-berry), cymose {Malus, apple, Sorbus, moun-
tain ash) or simple {Cotoneaster, evergreen or fire thorn).

Flowers. — The flowers (Fig. 157) are regular, perfect, and
usually with a concave or cup-shaped receptacle or torus to
which is attached a five-lobed or five-toothed calyx, five sepa-
rate petals, numerous distinct stamens and a one- to five-
celled ovary. The ovary is ordinarily five-celled, and the
carpels are wholly or partly united. The carpels vary in
texture from parchment-like (Malus, etc.) to bony (CratcB-
%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 Amelanchier, 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

POMACES 367

Geographical. — The family is of wide geographical distribution, there being
dose to 225 species within about 20 genera. Most of the species occur in
north temperate or boreal regions.

Key to Import.vnt Genera of Pom.vce.e

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

Ovules one in each cavitj^, Amdanchicr (service-berry, June-berry).
Ovules (usually) two in each cavity.

Flesh of the pome with grit-cells, Pynis (pear).
Flesh of the pome without grit-cells. Mains (apples and crab-apples).
Ovules many in each carpel, Cydonia (quince).

MALUS (Apples)

Stems. — Malus species are either trees or shrubs. In the
apple, all rapid-growing shoots develop only leaf buds.
Flower buds, which in the apple are "mixed" buds, are al-
most always borne on the ends of ''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-

368

ROTANY 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

Fig. 153. — Spur of Yellow Transparent apple.

Arid Regions") have noted that in certain districts of Colo-
rado many varieties produce flower buds in the axils of leaves
on the growth of the current season and that one-year-old spurs

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
young trees, and in many varieties. Different
forms of fruit branches occur; furthermore the
same variety, or even tree, may bear more than
one sort of fruit branch. Frequently, it has
been noted that spurs bear annually, instead
of biennially, as is the rule. In such a case,
fruit buds are developing on a spur at the same
time that an apple is maturing.

It is not always an easy matter to distinguish
between the fruit and leaf buds of apple.
Generally, fruit buds are rather thick and
rounded, while leaf buds are smaller and more
pointed.

It has been shown that fruit buds are differ-
entiated very early, and may be distinguished
by microscopic study, from leaf buds, as early as the last
week in June of the year preceding the opening of the flower.
The above has been reported by Drinkard, and Kraus has
observed that in the Yellow Newton apple, under Oregon
24

Fig. IS4-—
Mature Jona^
than apples
from axillary
flower buds.
{After Pad-
dock and
Whipple.)

370 BOTANY OF CROP PLANTS

conditions, the fruit and leaf buds are differentiated in early
July, and in early varieties, even by the latter part of May.

The form of the tree, nature of twigs, branches, bark and
leaves vary a great deal in the many varieties of apples.

Leaves. — These are simple, alternate, and toothed or
lobed; the stipules are free from the petiole.

Inflorescence. — It will be recalled that the buds contain-
ing flowers are mixed buds. Hence, when each opens there
is developed a very short axis bearing closely crowded leaves
and flowers. On this axis, the flowers are apical, the leaves
basal. The flowers may be so crowded that the cyme is
umbel-like in appearance. In most cases, the inflorescence
is terminal, but, as has been indicated above, it is axillary
in some varieties. The number of flowers in a single mixed
bud may vary from two or three to eight or ten. As a rule,
but one flower matures its fruit, thus illustrating the struggle
for existence among the different individual flowers.

The determinate.inflorescence, cyme, of apple is not always
definitely so. It will be remembered that in the cyme type
of inflorescence the flowers open in order from the inside
outward. Sometimes the central flower is tardy in its
development, and often the central and some of the laterals
may open simultaneously.

Flowers and Their Development. — The development of
the apple flower (Yellow Newton) has been worked out by
Kraus. A longitudinal section (Fig. 155) of a growing axis
shows a number of bracts and bud scales surrounding it; on
the sides of the axis, appear the primordia of flower buds and
leaves. The primordia of sepals are the first to appear.
The torus develops especially toward the outer edge by a
growth of the cells beneath the developing calyx, and finally
takes on a concave shape. The torus continues to uprise
during the development of petals and stamens, both of which

POMACES

371

are seen to arise from the concave sides of the torus. Follow-
ing the appearance of sepal primordia, appear petal primor-
dia, then those of stamens, and lastly those of the carpels.
The succession of floral cycles is acropetal, i.e., in order
from without to the inside.

Fig. 155. — Diagram showing the development of apple. Dotted area repre-
sents pith. Not drawn to scale. {After Kraus, Oregon Agr. Exp. Sla.)

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.

372 BOTANY OF CROP PLANTS

Pollination and Fertilization. — The literature on this
subject is extensive. Cross-pollination is the rule and
self-polHnation the exception in the apple and pear. Ex-
periments have shown that the wind aids but Httle in cross-
polhnation, and that insects, chiefly the honey bee, are
relatively more important The bee is attracted to the
flowers by the nectar which is produced rather abundantly.

Fig. 156. — Floral diagram of apple (Malus sylvestris). Note that the sta-
mens are in three distinct whorls. {After Kraus.)

Self -sterility and Self -fertility.- — Many apples and pears
are self-sterile, that is, will not fertilize their own pistils.
In such cases, pollen from another variety will usually result
in fertilization. Self-steriHty 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 fertiUzed 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 soHd blocks of Spitzenburg, for
example. It should be alternated with rows of some one of

POMACES

373

the other varieties the pollen of which is capable of fertilizing
it. It is no doubt true that the failure of many varieties to
set fruit is due, in part, to self-sterility.

Effects of Strange Pollen. — The secondary effects of for-
eign pollen on the mature fruit have received considerable at-
tention. It is claimed by many that the pollen from one va-
riety when placed on the stigma of another, immediately

Fig. 157. — Apple (Malus

sylvestris). Median
flower.

longitudinal section of

impresses its characteristics upon the fruit. It is difficult to
understand how foreign pollen could have any considerable
effect of this kind. The flesh of the apple is receptacle for the
most part. The sperm nuclei of the pollen, of course, do not
come into contact with the nuclei of the receptacle cells. It is
altogether possible, however, that uniformity of crop, percent-
age of set, and size of fruit are immediately affected by
strange pollen.

374 BOTANY OP CROP PLANTS

Parthenocarpy. — As a general rule, lack of fertilization of
the ovules in the ovary is followed by the shedding of the
blossoms; the ovary fails to develop completely if a good
number of its ovules are not fertilized. However, develop-
ment of the ovary does sometimes occur although fertiliza-
tion fails. Such an unusual development of carpels is called
parthenocarpy. This phenomenon is not unknown in the
apple. With certain sorts of both apples and pears, fruits
weighing loo grams have been developed without fertiliza-
tion. Of course, parthenocarpic fruit is seedless. There are
among cultivated plants many which bear seedless fruit.
We noted that in the common Mission figs the fruit matures
normally without fertilization of the ovules. Seedless to-
matoes, egg plants, English forcing cucumbers, oranges,
grapes, and bananas are quite common.

The Fruit and Its 'DQveloi^m.Qnt— Morphology. — There
are two common opinions as to the nature of pomaceous
fruits:

1. Flesh is thickened calyx tube.

2. Flesh is receptacle or torus closely connected with the
carpels.

The recent work of Kraus appears to establish the latter.
In following through the development of the flower (Fig.
155), it is seen that the receptacle, by more rapid growth at
the sides than toward the center, becomes urn-shaped and
bears on the rim and inside face, calyx lobes, petals, and
stamens. In the development of the fruit, there is a con-
tinuation of the enlargement of the receptacle ; the throat of
the receptacle becomes narrow, and through it the styles pro-
trude; and the connection between receptacle and carpel
tissues becomes a very close one; hence receptacle makes up
the greater portion of the flesh of the apple.

Ripening Process. — Important chemical changes take place

POMACES 375

in the ripening process. The content of sucrose (cane sugar)
increases steadily in the ripening process up to a maximum
and then suddenly decreases. There is a rapid decrease of
starch throughout the entire period. Invert sugar (a mix-
ture of glucose and fructose) increases throughout the ripen-
ing period while the total sugar increases up to the date when
starch entirely disappears, after which time it fluctuates
sUghtly. MaUc 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 hne (Fig. 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 Hne. 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 slight separation of the cells, an
increase in the regularity of the cell outline, in the size of
intercellular spaces, and amount of intercellular air.

'^Mealiness." — This results from a softening of the middle
lamellae; those varieties that are comparatively very mealy
have correspondingly weak 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 Hne.

376

BOTANY OF CROP PLANTS

POMACES 377

Cross-section of Fruit. — In a median cross-section of the
apple fruit (Fig. 158), the relation of carpels and receptacle is
well made out. The five carpels radiate from the center.
Each carpel is composed of a parchment-like endocarp,
fleshy mesocarp, and fleshy exocarp. The pith of the re-
ceptacle, which is in reality stem, surrounds and unites
with the carpels; the pith is without vascular bundles. As a
rule, there are ten primary vascular bundles seen in the
median cross-section. They mark the limits of the pith, all
tissue outside of them being cortex of the receptacle.

The tissues of the carpels and pith are very similar. How-
ever, the tissue of the carpels bears a network of very fine
vascular bundles, while that of pith is without such a network.
Many observers have wrongly considered all tissue from
parchment-like tissue, surrounding the seed cavities, out to
vascular ring, inclusive, as carpellary, whereas others have
considered only the parchment-like tissue as carpellary.

The ten primary vascular bundles are related in their
development with the carpels, as is shown by the fact that
when six carpels occur there are twelve bundles instead of
ten, and when there are four carpels, eight bundles.

Longitudinal Section of Fruit. — In longitudinal section
(Fig. 158), the flesh is seen to be separated into two parts by
a distinct fine, the "core Hne." 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

378 BOTANY OP CROP PLANTS

be seen in a line at right angles to an axis from stem end to
calyx end. Form terminology includes such terms as round,
oblate, conical, ovate, oblong, elliptical, etc. The flower
stem persists in the fruit. The depression about the stem
is termed the cavity. It varies in shape and depth in the
different varieties. At the opposite end from the cavity is
the basin. This also varies in character and is of taxonomic
value in the classification of fruits. The remains of the
calyx are persistent within the basin of the common apple.
In the pure Siberian Crabs, the calyx is deciduous, while in
hybrid forms of Siberian Crabs and in the common apple
it is partly deciduous. The dried stamens and styles may
be seen within the calyx lobes.

The stamens may be basal, situated near the base of the
calyx tube; median, near the middle; or marginal, near the
outer edge. The calyx tube itself varies in shape from con-
ical to funnel-shaped. The calyx segments, five in number,
vary in their arrangement in the mature fruit. They may
be divergent, that is, reflexed, erect convergent, when their
margins touch, flat convergent, when they are flat and close
the tube, and connivent, when they are overlapping. In a
median transverse section, the "cells" in different varieties
vary in shape and relation to the axis of the apple. They
may be "open" or "closed," axile or abaxile. When the
walls extend to the axis, the cells are axile, and when they
are distant from the axis, and unsymmetrical, they are abaxile.
When the core line meets inside the calyx tube, the core is
said to be meeting; if near the calyx tube, it is clasping.
The core outline varies in shape. There are usually two
seeds in each cell cavity; however, there may be more than
two or fewer or sometimes none at all. They vary in size
and color.

POMACEiE 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, M alus 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 haccata
(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 anguslifolia (narrow-
leaved crab-apple).
Leaves persistently pubescent or tomentose beneath.

Leaves narrowed at base; pomes small, i to i^ inches in diameter.
Pedicels slender, i to i}4 inches long, Malus ioensis (Western crab-
apple).
Pedicels stout, }i to i inch long, Malus soulardii (Soulard crab-
apple).
Leaves rounded or subcordate at base; pomes large, 2 to 4 inches in
diameter Malus sylvesiris (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 H 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.
sylvesiris. The Siberian crab grows wild from Siberia to Manchuria and the
Himalaya region.

M. angustifolia, Narrow-leaved Crab-apple. — It is a low tree with small,
narrow, lanceolate leaves, few-flowered cymes, fragrant pink flowers, and
fruit about i inch in diameter. It is distributed from Pennsylvania to
Tennessee and Florida.

M. coronaria, American .Crab-apple. — This is a small, bushy tree with
thorny, crooked branches, ovate or triangular-ovate, sometimes three-lobed,
leaves, large flowers, with a persistent calyx, and fruit that is i to i3^ inches
in diameter, somewhat flattened endwise, greenish-yellow, waxy, fragrant, and

38o

BOTANY OF CROP PLANTS

Fig. 159, — Leaves of Mains species. A and B, western crab (M. ioensis);
C, flowering crab (M. floribunda); D, narrow-leaf crab (M. angustif olia) ; E,
Soulard crab (M. soulardi); F, common apple (Wealthy) (M. sylvestris); G,
American crab (M. coronaria); H, Siberian crab (M. baccata). X }-i.

POMACES 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
Malus ioensis.

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

M. sylvestris, Common Apple. — The common apple is a large tree with
twigs and under surface of leaves gray-woolly; the flowers are in close clusters,
and on short pedicels; the fruit is very variable. There are numerous varieties
differing as to form, size, color, and taste of fruit. In order to keep the va-
rieties true to type, propagation is vegetative rather than sexual.

The common apple is considered to be a native of western Asia and south-
eastern Europe. In eastern United States, it occasionally escapes from cul-
tivation. It is grown commercially in all parts of the United States except
in Florida, the regions bordering the Gulf of Mexico, and warmer portions of
the Southwest. The leading apple-growing section of this country is from
Nova Scotia south and west to Illinois and Missouri.

The Classification of Apples ( 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 Mo or with modifications. He divided the
varieties into seven classes, and these into orders. These
classes are as follows: Ribbed apples, Rose apples, Ram-

382

BOTANY OP CROP PLANTS

hours, Reinettes, Stripelings, Pointlings, and Flat apples.
Beach gives the following groups of varieties: Fall Pippin,
Rhode Island Greening, Winesap, Fameuse, Alexander or
Aport, Wealthy, Duchess of Oldenburg, Northern Spy,
Blue Pearmain, and Rails-Genet.

Composition. — According to the determinations of Al-
wood and Davidson, the average amount of juice recovered
from summer apples by grinding and pressing is 53.2 per
cent. ; from winter fruit 53.92 per cent. Crab-apples show an
average juice content of 57.31 per cent. The average water
content of the whole apple varies from 80 to 86 per cent, of its
total weight. It is not possible, of course, to remove all the
juice from apples by ordinary pressing, and furthermore, the
amount of juice recovered depends upon the grinding and
pressing methods. The above workers chemically analyzed
the juice and pomace of many varieties. The percentage
composition of the juice is shown in the following table:

Specific
gravity

Total
solids

Total
sugar

Invert
sugar

Cane
sugar

Acids as
H2SO4

Tannin

Summer varieties
Autumn varieties
Winter varieties. .
Crab-apples

1.049
I -054
1.056
1.062

12.33
13 76
14.29
15.69

9-53
10.66

11-43
II. 71

5. 85
6.93
7.04
8.08

3-So
3-53
4.16
3.45

0.33
0.36
0.41
0.50

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 quahty,
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
maUc acid present. So-called "sweet apples" do not neces-

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 slightly, and also kill any or-
ganisms that may be present. The most common drying
method is to pass hot air under high pressure over the fruit.
After removal from the drying machine, the apples are al-
lowed to sweat for several days either in the open air or in
well-ventilated chambers. They are then ready for packing.

384 BOTANY OF CROP PLANTS

Production of Apples in the United States.^ — In 191 5 there
were produced 230,010,000 bushels of apples in this country,
at an average farm price per bushel of 74.6 cents. The ten
leading States in the order of their production were New York,
Missouri, Ohio, Pennsylvania, Illinqis, 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

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-like, the flowers appear before
the leaves, and the calyx is deciduous.

POMACES 385

PYRUS COMMUNIS (Common Pear)

Stem. — The common pear is a tree of upright-growing
habit. The flower buds are mixed and terminal, as in most
apples. Paddock and Whipple have shown that, in Colorado
at least, the Anjou pear may produce blossom buds on one-
•year-old spurs; that Bartletts may form bloom on the end of
the last year's growth; that Anjou, Bartlett, Duchess, and
Kieffer varieties produce bloom in axillary buds on the last
year's growth, and that a number of varieties, as Anjou,
Bartlett, Duchess and Sheldon, are annual bearers. There
are usually from six to nine flowers in a bud. The ''spurs''
are similar in appearance and development to those of the
apple.

Leaves and Flowers.— The leaves are ovate, elliptic, and
finely toothed. The flowers are in simple terminal cymes;
the pedicels are 2 to 3 inches long, and appear with the leaves;
the petals are five in number, rounded, short-clawed, and
usually white; the sepals are persistent; the styles are distinct
to the base.

Fruit.— The fruit varies in shape, usually tapering to the
base; the flesh is with grit cells (Fig. 160) (groups of stone cells
imbedded in parenchyma) .

Geographical.— The common pear is probably a native of southern Europe
and Asia. In many localities, it has escaped from cultivation. There are
numerous cultivated varieties. The pear thrives best in the northern half of
the United States.

PYRUS SEROTINA CULTA (Sand, Japanese, or Chinese Pear)

This is a strong-growing tree with broad-ovate, long-
pointed leaves that are very sharply toothed. The large
flowers appear before the leaves. The fruit is hard and
russet-like, keeps well, and has a deciduous calyx.

The tree is a native of Chma. Chmese Sand, Madame von
25

386 BOTANY OF CROP PLANTS

Siebold, Mikado, and Japanese Sand are a few of the varieties
growniin;the United States. It is also often used to hybrid-
ize with ourjcommon pear, the Kieffer variety being the
best-known on^ resulting from such a cross.

Self -sterility in Pears. — The work of Fletcher has pointed
out the reasons for the barrenness of many pear orchards.
Much of this is due to self-sterility, that is, the inabihty of
the pollen of a variety to fertihze the ovules in the pistils of
that variety. It has been frequently observed in many
portions of the country that when a certain variety of pear, as
well as other fruits, was planted thickly, there was often pro-
nounced seK-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

Bartiett X Bartlett i in 513 2 .00

Bartlett X Kieflfer i in 10 3.00

Bartlett X Anjou i in 7 3-75

Bartlett X Lawrence i in 9 3 . 50

Bartlett X Duchess i in 10 3 . 50

The following table shows similar relations in the case of
Kieffer pears:

Pollinations Av. number of

blossoms set

Kieffer X Kieffer i in 253

Kieffer X Bartlett i in 5

Kieffer X Le Conte i in 7

Kieffer X Lawrence i in 6

Kieffer X Duchess i in 5

Kieffer X Anjou i in 4

Kieffer X Clairgeau i in 3

Kieffer X Garber i in 7

POMACES .387

From these experiments, Fletcher recommends (under
Virginia conditions, at least) that Anjou, Lawrence, Duchess
and Kieffer are desirable varieties to plant with Bartlett,
and that Bartlett, Le Conte, Garber, Lawrence, Duchess,
Anjou, and Clairgeau are desirable varieties to plant with
the Kieffer.

It is not probable that the same degree of self-sterility
for a given variety will prevail under different climatic and
soil conditions. Furthermore, it must be held in mind that
no immediate 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 numerous instances cited
of the influence of the stock upon the scion, or scion upon the
stock. ^ When pears are grafted on the more slowly growing
roots of the quince, the stock in this case retards the growth
of the pear, and dwarfing results. The common quince
used in Angers and the varieties ordinarily dwarfed are
Angouleme, Bartlett, Anjou, and Louise Bonne. Dwarfing
appears to improve the 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.

388 BOTANY OF CROP PLANTS

CYDONIA (Quince)

The genus has much the same characters as Malus and
Pyrus, except that each of the five carpels has several seeds,
covered with a mucilaginous pulp, and the large flowers are
in small clusters or sometimes single at the tips of branches.

There are several species of Cydonia, the most common
being C. ohlonga (edible quince).

CYDONIA OBLONGA (Common Quince)

Stem. — The common quince is a small tree seldom over 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 >^ 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.

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 Compositdon 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, 1915.
• Brooks, Chas. : The Fruit Spot of Apples. Bull. Torrey Bot. Club, 35 : 423-

456, 1908 (includes notes on structure of fruit).
BuDD, J. L., and Hansen, N. E.: American Horticultural Manual. Part II,

Systematic Pomology. John Wiley & Sons, 1911.
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 ruitfulness and Self-
sterility in Apples. Jour. Hort. Soc, 39: 615-628, 1914.
Decaisne, Joseph: Memoire sur la famille des Pomacees. Nouvelles Ar-
chives du Museum, X, pp. 113-192 (Paris), 1875.

Le jardin fruitier du museum, un iconographie de touts les especes et
varietes d'arbres fruitiers cultives dans cet etablissement. Firmin
Didot Freres.
Drinkard, a. W.: Fruit-bud Formation and Development. Rept. Vir. 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, 1911.
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.

390 BOTANY OF CROP PLANTS

Investigations of Flower Buds. 17th Ann. Rept. Wis. Agr. Exp. Sta., 266-

285, 1900.
Investigation of Flower Buds. i8th Ann. Rept. Wis. Agr. Exp. Sta. 304-

316, 1901.
Origin and Development of the Apple Blossom. Am. Gard., 22: 330 and
346-347, 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.: Traite de la taille des arbres fruitiers, ed. 12, 123,

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

1915-.
Kraus, E. J. : The Pollination of the Pomaceous Fruits. I. Gross Morphology
of the Apple. Ore. Agr. Exp. Sta. Res. BuU. I, pt. I: 1-12, 1913.
The Study of Fruit Buds in Oregon. Ore. Agr. Exp. Sta. Bull. 130: 12-21,

1915-
Variation of Internal Structure of Apple Varieties. Ore. Agr. Exp. Sta.

Bull. 135: 3-42, 1916.
Kraus, E. J., and Ralston, G. S.: The Pollination of the Pomaceous Fruits.

III. Gross Vascular Anatomy of the Apple. Ore. Agr. Exp. Sta. Bull.

138: 4-12, 1916.
Lewis, C. I., and Vincent, C. C.: Pollination of the Apple. Ore. Agr. Exp.

Sta. Bull. 104: 1-40, 1909.
McAlpine, D.: The Fibro-vascular System of the Apple and its Function.

Proc. Linn. Soc, N. S. Wales, 36: 613-625, 1911.
The Fibro-vascular System of the Quince Fruit Compared with that of

the Apple and Pear. Proc. Linn. N. S. Wales, 37: 689-697, 1912.
Paddock, W. and Whipple, O. B.: Fruit Growing in Arid Rfegions. Mac-

Millan Co., 1910.
Pickett, B. S.: Factors Influencing the Formation of Fruit Buds in Apple

Trees. Trans. Mass. Hort. Soc, pt. I: 57-72, 1913-
Sandsten, E. p.: Some Conditions Which Influence the Germination and

Fertility of Pollen. Wis. Agr. Exp. Sta. Research Bull. 4: 149-172,

1909.
Shaw, J. K.: The Technical Description of Apples. Mass. Agr. Exp. Sta.

Bull. 159: 73-90, 1914-
Waite, W. B.; The Pollination of Pear Flowers. U. S. Dept. Agr. Div. Veg.

Path, and Phys. Bull. 5: i-iio, 1894.
West, G. H.: The Pollination of Apples and Pears. Trans. Kans. State

Hort. Soc, 32: 38-50, 191 2.

CHAPTER XXVIII

DRUPACE^ (Plum Fanuly)

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.

are

com-

The

often

Leaves. — The leaves
alternate, petioled and
monly finely toothed,
teeth and petiole are
glandular (Fig. i6i) ; the stipules
are early deciduous.

Flowers. — The perfect, regu-
lar flowers (Fig. 162) are
solitary (apricot), or in racemes (wild black cherry, etc.),
umbels (sweet cherry, etc.), or corymbs (perfumed cherry).
The calyx is free from the ovary, five-lobed, bell-shaped or
391

Pig. 161. — Leaf of peach
(Amygdalus persica). The base
of the leaf considerably enlarged,
in B.

392

BOTANY OF CROP PLANTS

tubular and with its lobes imbricated in the bud; the corolla
has five distinct petals; there are numerous stamens. In a

Fig. 162. — Floral diagram of Prunus.

^nm oj receplacle

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

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 pistil, situated at the
bottom of the hollow receptacle; the ovary is one-celled and
two-ovuled ; the style is . single and terminal and bears a
small, head-shaped stigma.

^P'^te^f

otyledons

fcotmaons
of emhnjo

cahx

Fig. 164. — Median lengthwise section of young cherry frui

Fruit.^ — The fruit is a drupe (Fig. 164), that i
a single seed surrounded by a stony endocarp, fleshy meso-
carp, and an outer skin or exocarp (epicarp). However, if
one examines the young ovary of a Frunus flower he wiU find

394 • BOTANY OF CROP PLANTS

two ovules; one of them aborts, the other develops into a
seed. The endosperm is absent, or present only in a small
amount. The cotyledons are fleshy.

The only genus of any importance is Prunus. It has the
characteristics of the family.

PRUNUS

This genus includes the plum, cherry, ahnond, peach and
apricot. These main groups may be distinguished by the
following key :

Key to Main Groups of Genus Prunus

Stone smooth.

Flowers clustered; fruit glabrous.
Fruit large, usually grooved, covered with a bloom; stalk short; stone
usually compressed, longer than broad; leaves convolute in the bud
(Fig. loi), Plums.
Fruit small, usually not grooved, not covered with a bloom; stalk long;
stone usually globular; leaves conduplicate in the bud (Fig. loi),
Cherries.
Flowers solitary or in two's; fruit velvety at first. Apricots.
Stone pitted or furrowed.

Flesh soft, thick, juicy, Peaches.
Flesh hard, thin, dry. Almonds.

The genus has about 90 species, nearly all of which occur
north of the equator; they are widely distributed in both
eastern and western hemispheres. Most species are con-
fined to the temperate zone. The evergreen cherries include
a group found in the tropics and sub tropics.

PLUMS

Stems. — The plums are shrubs or small trees. The
different species vary considerably in bark and twig charac-
ters. The bark of southern forms is lighter in color than
that of those growing in the north. Plums have a tendency

DRUPACE^

395

to produce spurs (Fig. 165). Flower buds are, as a rule, on

these spurs, one spur bearing from 2 to 20 buds. The spur

may terminate in a leaf bud. However, in most plums, true

terminal buds are seldom formed. In

such cases, if the last lateral bud is a

branch bud, this continues the growth

of the branch in a straight line. The

Hne between the two seasons' growths

is not as sharp, in this case, as when a

terminal bud develops. If the last

lateral bud is a flower bud, the twig

usually dies back to the lateral branch

developed from the last branch bud.

In all plums, the flower buds are lateral.

Flower buds usually stand out at an

angle of about 30°, while leaf buds are

more appressed to the stem.

Leaves. — The leaves of plums vary a
great deal in size, form, color, surface,
thickness, and margin. In some species,
the serrations are tipped by glandular
prickles. Stipules are present. The
leaves are convolute in the bud (Fig.

lOl).

Inflorescence. — The flower ^^ buds of
the plum, unHke those of the apple and
pear, bear only flowers. They may
break open before, simultaneously with,
or after the leaf buds. The flowers are
in fascicled umbels. The number of
flowers in the bud varies from one to five, two and three
being the most common numbers.

Flowers. — The receptacle forms a hollow cup (Fig. 163).

Fig. 165. — Twig of
Domestica plum
(Prunus domestica) .
{After Paddock and
Whipple.)

396 BOTANY OF CROP PLANTS

On its edge, are arranged five sepals, five petals, and fifteen
to twenty stamens. There is a single pistil bearing one style
and one stigma. The pistil is at the bottom of the recep-
tacle. There are two ovules in the young ovary; one of them
aborts during maturation of the fruit.

"Fertilization. — Many of the plums are practically self-
sterile. The native plums exhibit the greatest self-steriHty ;
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-fertiHzation 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 Hght crop unless a
large number of bees are present in the orchard at the time
of blooming. They appear to be self-sterile to some extent.
Imperial prune trees that were enclosed in a tent from which
all insects were excluded set no fruit. It seems that, with the
Imperial prune, fruit is not set unless pollen is brought from
other trees. It is distinctly self-sterile. All Prunus species
are insect-poUinated 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

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, 1911; and Wight, W. F., "Native American
Species of Prunus," Bull. 179, B. P. I., 1915.

Key to Principal Species of Pltjms *

Flowers in clusters of one or two (three in P. Iriflora), 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. Iriflora.
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. angustifolia).
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. riigra.
Leaves narrow, ovate, ovate-lanceolate, the margin rarely doubly serrate;
flowers 8 to 15 millimeters broad; calyx rarely reddish, the lobes entire,
either glandular or glandless.
Leaves thick, slightly lustrous on upper surface; veins conspicuous below;

margin coarsely and irregularly serrate, P. horlulana.
Leaves usually thin, lustrous on upper surface, veins not conspicuous
below, margin finely and evenly serrate.
Leaves usually 6 to 10 centimeters long; calyx lobes glandular, P.

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

* Adapted from The Plums of New York by Hedrick.

398 BOTANY OF CROP PLANTS

DISCUSSION OF SPECIES

Prunus domestica. — This is a vigorous-growing tree
which may reach a height of 30 or 40 feet. The leaves are
ovate or obovate, elliptical or oblong-eUiptical; the upper
surface is smooth, the lower often j&nely 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 quahty. The stone is either free or clinging.
Important varieties are Reine Claude, Bavay, Spaulding,
Yellow Gage, Washington, etc.

2. Prunes. — A prune is any plum that can be cured without
removing the pit. All plums with a large percentage of sugar
make good prunes. The fruit is large, oval, usually com-
pressed, blue or purple, and with a firm, greenish, yellow, or
golden flesh, and free stone. Prunes are raised on the Pacific
Coast. The industry there has become a large one. Im-
portant varieties are Italian, German, Agen, Tragedy, Ten-
nant, Sugar, Giant, Pacific, and Ungarish.

Preparation of Prunes. — In the preparation of prunes, the

DRUPACEiE 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 utiHzed. 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 prunes a shiny
appearance, and also steriHzes the exterior.

3. Peridrigon Plums. — This is a prune plum grown only
in France.

4. Yellow Egg Plums. — The fruit of these is large, in fact
the largest of plums, long-oval, and has a yellow or purple
skin, and yellow flesh. Well-known varieties are Yellow
Egg, Red Magnum Bonum, Golden Drop, and Monroe.

5. Imperatrice Plums. — These are medium-sized, dark
blue plums, with thick skin, firm flesh, and clinging stones.
Such varieties as Ickwor^h, Arch Duke, Monarch, Shipper,
Arctic, etc., belong to this group.

6. Lombard Plums. — This group includes the reddish or
mottled varieties of Domestic plums. Lombard, Bradshaw,
Victoria, Pond, and Duane are well-known varieties.

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 sHghtly
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 chnging or free
stone.

Varieties of this species are hardy and thrifty. The species
has been in cultivation over 2,000 years, but in all that time
has shown but little variation. Insititia plums rank second

400 BOTANY OF CROP PLANTS

to Domesticas. The species grows wild from the Mediterra-
nean northward into Norway, Sweden and Russia. Insititia
plums fall into four groups as follows:

1. Damsons. — These are spicy plums, mostly sour, and
much desired for preserving.

2. 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 round, yellowish or golden plums
with a free stone and resemble much the green gages as to
quaHty.

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.

Primus cerasifera. — These are the cherry or Myrobalan plums. They are
hardy, thrifty varieties, free from disease, readily adaptable and most suitable
for hybridizing. The trees are small, bloom profusely, and bear a small,
round, cherry-like plum from 3^ to i inch in diameter. They are adapted
to ornamental usage. They are also used as stocks upon which to bud
other plums. \

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.

Prunus americana. — This is our most important native plum. It grows
wild from New Mexico to Manitoba, and eastward to the Atlantic Coast.
Not being able to raise European plums in the Mississippi VaUey, Americans
domesticated the native American plum. Varieties of this species are hardy.
The American plum tree is usually small, with rough, shaggy bark. The
fruit is reddish or yellowish. Altogether, there are about 260 varieties of
the americana. Waugh finds that they often bear defective pistils or
stamens, or that they are often protandrous or protogynous. From his
observations, he recommends some provisions for cross-fertilization when
planting americanas.

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

DRUPACE^

401

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

Prunus 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.

Pninus angustifolia. — The Chickasaw plum is a small tree, 6 to 10 feet
high, sometimes shrubby. The fruit is small, almost globular, flesh yellow,
and of good quality. It ranges from Delaware to Louisiana and westward
to Arkansas and Texas. Its varieties do well in the Southern States.

The two subspecies, watsoni and varians, have varieties of some horti-
cultural value, such as Purple Panhandle, African, Clark, Emerson, etc.

CHERRIES

corolla
I .ca\\j.

Description.^ — The cher-
ries resemble plums in
many respects. The bark
of the cherry separates in
rings. The flower buds are
usually found on short
spurs (Fig. 166). In some
sour cherries, however,
axillary flower buds occur
on long, strong shoots.
These buds produce fruit
the following spring. Since
the lateral buds in such
shoots are flower-bearing,
no lateral branches are pro-
duced, and the result is a
long, naked branch. On the
spurs, the flower buds are
axillary and a branch bud
terminates the short shoot.

The flower buds bear only flowers and no leaves (except very
rudimentary ones which persist but for a short time). There
26

)^rowih

Fig. 166.-

-Spur of sour cherry (Prunus
cerasus) .

402 BOTANY OP 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
CaKfornia 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 species, Prunus avium, the
sweet cherries, and Prunus cerasus, the sour cherries.

PRUNTJS 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-steriHty has been reported in the sweet cherry orchards
of the Northwest. The fruit is variously colored, spherical
to heart-shaped, with flesh soft or hard, usually sweet, and
with the skin adherent to the flesh.

Geographical. — The species is a native of Europe. It has been cultivated
in this country for many years, and in some places has escaped from
cultivation.

Groups of Sweet Cherries. — The sweet cherries include
four general groups:

I. Mazzards: — The fruit is small, and varies in shape and
color. Mahaleb and mazzard stocks are the two common

DRUPACE^

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 CERASUS (Sour Cherry)

Description. — Sour cherry trees are smaller
than those of sweet cherries. They "sucker ^
readily from the root. The bark is gray-
brown and quite smooth; lenticels are con-
spicuous. The leaves are thick, ovate or
ovate-lanceolate, abruptly acute or acuminate at the tip,
variously toothed, becoming smooth on both surfaces, usually
erect, and with short, strong petioles. Flowers appear before

Fig. 167. — Twig
of sweet cherry
(Prunus avium).
(After Paddock
and Whipple.)

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.

Geographical. — The species is a native of
Europe and an occasional escape from cultiva-
tion in this country.

Groups of Sour Cherries.^The sour
cherries include two general groups:

1. Amarelles. — These cherries are pale
red in color, have colorless juice, and are
generally somewhat flattened on the
ends. They have less acid than dark-
colored cherries. Montmorency and
Early Richmond are the most common
Amarelles,

2. Morellos or Griottes. — These are
cherries with dark red fruit and dark
juice, and they vary from spherical to
heart-shape. Common varieties are
Ostheim, Olivet, Louis Phihppe, and
the Morello.

Fig. 168. — Twig of
sour cherry (Prunus
cerasus). {After Pad-
dock and Whipple.)

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. pumila, P. cuneata, and P.
besseyi. P. pennsylvanica is sometimes used as a
stock on which to bud the sour cherry.

Prunus mahaleh, 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

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 utihzed 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

4o6

BOTANY OF CROP PLANTS

growth, they will be found along the central portion of the
twig; while on feeble-growing branches, they usually occur
singly, and are quite evenly distributed along the entire

length. However, not all
the flower buds are formed
on the long shoots. Many
are developed on ex-
tremely ' short spurs, but
always axillary; usually
the flower buds are single
in such short growths.

Leaves. — These are usu-
ally ovate, often somewhat
heart-shaped at the base,
abruptly short-acuminate,
smooth above, sHghtly
hairy ^beneath, finely
toothed, on glandular
petioles, and convolute in
vernation.

Inflorescence and
Flowers. — The flowers are
soHtary or in pairs, pink-
ish, sessile or nearly so.
Morphologically, the
flowers are similar to those
of plum, cherry and other
Prunus spp.

Fruit. — This is much
like a peach in color and shape; the skin is velvety at first,
but becomes smooth at maturity; the flesh is always
yellow. The stone (endocarp and seed) is flat, smooth, and
grooved on one edge. In the maturing of the fruit, the

Fig. 169. — Twigs of- apricot (Prunus
armeniaca). (After Paddock and
Whipple.)

DRUPACE^

407

parts of the flower are cut off by a basal ring of growth, as
described in the plums.

Distribution. — The species is considered to be a
native of southern Asia. It is now cultivated in
most temperate climates. In the United States, the
practice is to graft apricots on to the roots of plum or
peach.

Other Species. — There are several other species
of apricots besides P. armeniaca, but none of them
bear fruit of marketable size. They are generally
planted as ornamentals. Among such are P. sibirica,
the Siberian apricot, P. dasycarpa, the purple or black
apricot, and P. 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 pe!0.ch (Prunus
persica). (After Pad-
dock and Whipple.)

408 BOTANY OF CROP PLANTS

a branch bud (Fig. 170). In this respect, they are similar
to the apricot.

Leaves. — These are conduplicate (Fig. 10 1) in the bud,
elHptic to lanceolate or oblong, and taper toward either end;
they are finely and sharply toothed, and on stout petioles.

Inflorescence and Flowers.— The flowers are normally
solitary in the axils of leaves and appear before the leaves;
they are large, pink, fragrant, and showy.

Fruit. — The fruit is subglobular, grooved slightly on one
side, has velvety skin, and hard flesh which may be free
(freestones) or adherent (clingstones) to the stone. The
stone is compressed, pointed, and pitted. The seed is of
the shape of an almond, aromatic, and sHghtly bitter.

Geographical. — The peach is a native of Asia, probably China. It was in-
troduced into Europe at a very early date, coming by way of Persia. This
fact accounts for the specific name, persica, and common name, peach.
The tree is now cultivated in temperate regions. Occasionally it is escaped
from cultivation, especially throughout our Northern and Middle States.

Types of Peaches.^ — The first system of classification of
peaches was worked out by Onderdonk, of Texas. He
divides the varieties of peaches into five classes or races,
based primarily upon the country in which they originated,
hence upon their range of adaptabihty.

1. Peen-to Race. — The stone is almost spherical (Fig.
171, C, D), somewhat compressed at the end, and with small
and round corrugations; the fruit (of original peen-to) is much
flattened; the skin is white, blotched with red, and flesh
white; the stone is free or cling. It is adapted to subtropical
regions. Varieties: Angel, Clara, Hall, Waldo.

2. South China Race ("Honey" Group). — The stone is
oval (Fig. 171, B), and its corrugations 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

DRUPACE^

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-to Race; E, 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, chng, 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 adaptability. Varieties: Belle, Lee Ray, Superb.
Elberta and several other varieties are considered crosses
between the North China and Persian races.

4IO BOTANY OF CROP PLANTS

5. Persian Race. — The seed is globular, with corrugations
prominent toward the apex (Fig. 171, E, F) ; the fruit is much
hke the preceding. The common varieties of peaches grown
in northern orchards belong to this race. Varieties: Crothers,
Foster, Late Crawford, Reeves, Salway, Walker.

In addition to the above, the Nectarine should be added
as a variety of peach. It differs from the common peach in
that its fruit is smaller, the skin is smoother, and the leaves
are commonly" more prominently toothed. There are both
freestone and clingstone nectarines. It is known that
nectarines appear on peach trees and peaches on nectarine
trees. Such fruits that thus appear are evidently "bud
variants."

Uses, and Production of Peaches in the United States. —
The fruit is used largely as a dessert, both fresh, dried and
canned. 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 191 5 was 64,218,000 bushels, which were
sold at an average farm price of 81.1 cents. CaHfornia 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\ommunis). The tree is much Hke the peach in
shape and 'size. The flower buds are axillary along with
branch buds, as in the peach and apricot. The leaves are

DRUPACE^ 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-fertiKzation. The drupe is much compressed. The
mesocarp (portion corresponding to the flesh of peach or
plum) is leathery and tough and separates readily at maturity
from the stone (endocarp and seed). The "unshelled"
almond of commerce consists of the thin, pitted, light-colored
endocarp, within which is the seed or "kernel."

The common almond is a native of Asia.

Types of Almonds.^ — The two general types or races of
common almonds are the hitter and the sweet. The difference
is in the composition and taste of the kernel. The sweet or
edible 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 ground, subjected to
great hydraulic pressure to remove the undesirable fatty
oil, and the residue ground again, fermented, and distilled
with steam. The distillate is almond oil and hydrocyanic
acid. This latter, deadly poisonous substance is removed by
treating the mixture with Hme and copperas.

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: 1-37 1, 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. Bull. 174: 127-132, 1916.
Hume, Harold H. : The Peen-to Peach Group. Fla. Agr. Exp. Sta. Bull. 62 :

505-519, 1902.
Onderdonk, Gilbert: Report of the Commissioner of Agr., 1887, pp. 648-

650. Containing the Original Classification of the American Varieties

of Peaches.
Powell, G. Harold: The Chinese Cling Group of Peaches. Del. Agr. Exp.

Sta. Bull. 54: 1-32, 1902.
Price, R. H.: The Peach. Tex. Agr.. Exp. Sta. Bull. 39: 803-848, 1896.
Quaintance, a. L.: The Development of the Fruit Buds of the Peach. Ga.

Exp. Sta. Rept. 13: 349-351, 1900-
Rabak, Frank: Peach, Apricot, and Prune Kernels as By-products of the

Fruit Industry of the United States. U. S. Dept., Bur. Plant Indus. Bull.

133: 1-34, 1908.
The Utilization of Cherry By-products. U. S. Dept., Bur. Plant Indus.

Bull. 350: 1-24, 1916.
Reimer, F. C: The Honey Peach Group. Fla. Agr. Exp. Sta. Bull. 73= 135"

153, 1904.
Wight, W. F.: Systematic Botany of the Plum as Related to the Breeding.

of New Varieties. Ann. Rept. Am. Breeders' Assn., 8: 488-497, 191 2.
The Varieties of Plums Derived from Native American species. U. S. Dept.

Agr. Bull. 172: 1-44, 191 5.
Native American Species of Pr«»M^. U.S. Dept. Agr. Bull. 179: 1-75,1915.

CHAPTER XXIX
LEGUMmOS^ (Pea Family)

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 applied to members of the
Leguminosae. Probably no family is of greater agricultural
importance than this one, unless it is the Graminese. Legu-
minous plants are comparatively rich in protein; this applies
to all portions of the plant, and not to seeds alone. For this
reason they help to balance the food ration of man and of
domestic 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-Hke structures. These organisms
have the power of fixing free nitrogen of the air. That is,
free nitrogen gas from the soil air is taken by the organism
413

414 BOTANY OF CROP PLANTS

and, together with other chemical elements, made a part of
its protein. It is probable that the legume bacteria, while
active in the nodule, are throwing off continuously nitroge-
nous substances which are absorbed directly by the plant
upon which they are growing. Moreover, when the nodules
decompose, their protein contents are ammonified, and
nitrified, and finally there is left in the soil, nitrates which are
available as a source of nitrogen for green plants. Legumes
are regularly employed as rotation crops with cereals, and
root crops. Since they are heavy soil feeders, they make
excellent crops to plow under.

Habit. — ^Leguminosae are either annual, biennial or peren-
nial; and are either herbs (peas, beans, alfalfa, etc.), shrubs
{Genista, dye-weed or green-weed), or trees {Rohinia and
Gleditsia, locusts), and a very few are vines {Vicia spp.,
vetches).

Leaves. — These are alternate on the stems, stipulate, and
mostly compound. They are generally odd-pinnate, that
is, a leaflet terminates the rachis of the leaf, as in Rohinia
(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).

Liflorescence. — The flowers are nearly always arranged in
racemes (pea), sometimes in a head (clovers), or spike-like
raceme (alfalfa), or spike (Glycyrrhiza, licorice).

Flowers. — These are irregular (Fig. 172); they have a
butterfly-hke shape, and for this reason, flowers of the pea
type are often spoken of as "papiHonaceous." The calyx
is normally four- to five-toothed or cleft, the teeth or lobes
being equal or unequal. The petals are usually five in
number, a broad upper one (standard, banner or vexillum),

LEGUMINOS^ 415

two lateral ones {wings or alee), 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) , as in
Lupinus, or nine are united and one is free (Fig. 188) (diadel-
phous), as in clovers and alfalfa, or rarely all stamens are
separate (polydelphous) , as in Sophora and Thermopsis.

Fig. 172. — Flower of Leguminosae. A, floral diagram of Vicia faba; B,
sweet pea"" flower, dissected, diagrammatic. {A after Eichler, B after Bergen
and Caldwell.)

The united stamens form a tube enclosing the pistil in
monadelphous and diadelphous forms. There is a single
superior pistil; the ovary is usually one-celled, sometimes
two-celled by the intrusion of the sutures, as in some Astraga-
lus spp., or occasionally several-celled by cross-partitions;
there is one style, and one to many ovules.

Fruit. — In nearly all members of the family, the fruit is a
legume or pod, that is, a fruit of one carpel which opens along
two, both the ventral and dorsal, sutures. The ventral
suture of the bean or pea pod, for example, is the one along
which the seeds are attached. In one tribe (Hedysareae) ,

4l6 BOTANY OF CROP PLANTS

the fruit is a loment, that is, a jointed indehiscent legume,
constricted between the seeds. The style, calyx, and
withered stamens are often partly persistent in the fruit.

Seeds. — The seeds are usually without endosperm; the
cotyledons are thick and full of food.

The seeds of legumes are noted for their great longevity.
Some have been known to retain their viability for 150 to
250 years. This is correlated with their very hard, imper-
meable seed coats. So-called "hard seeds" are very com-
mon in the pea family. Such seeds are tardy in their ger-
mination, either under laboratory or field conditions. As a
rule, only a portion of a crop of seeds is hard, although in
some cases the whole crop may be hard. It is claimed that a
larger percentage of hard seeds is produced in dry chmates
or when ripening takes place under dry seasonal conditions
than in moist climates or moist seasons. The permeabihty
of leguminous seeds can be increased by "scarifying,"
that is, passing them through a machine that abrases the
surfaces. The ordinary alfalfa huller is effective as an
abraser, as is shown by the experiments of Harringtjon who
found that alfalfa seed, grown tinder a variety of soil and
climatic 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), Pisum (pea).
Calyx lobes not leafy; stipules mostly small, pointed.
Style slender, bearded at the tip (Fig. 173, A;, Vicia (vetch).
Style flattened, bearded along the inner side (Fig. 173, B), Lathyrus
(vetchling).
Plants without tendril-bearing leaves.
Leaves palmately three-foliate (Fig. 183), TrifoUum (clover).
Leaves pinnately three-foliate, rarely five- to seven-foliate (Fig. 182). ,

LEGUMINOSiE 417

Flowers small, many in a cluster.

Flowers in slender, spike-like racemes, Melilolus (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 (bean).
Keel of corolla merely incurved, Vigna (cowpea).
Pods hairy, small, Soja (soy bean).
Leaves pinnate, with two pairs of leaflets, Arachis (peanut).

PISUM (Pea)

Description. — The plants are herbaceous trailers or
climbers with hollow stems. The leaves are pinnately
compound, with one to three pairs of leaflets, the terminal
one, and in some cases the upper lateral ones, modified as
tendrils, which are sensitive and prehensile; the stipules are
large and leaf-like (Fig. 19). The inflorescence is a few-
flowered axillary raceme. The
flowers are either white or pur-
plish, diadelphous, and bear a
single pistil with the style
bearded on the inner side (Fig.
173, A). The pea is capable of
self-fertilization although it
may sometimes be cross-ferti-
lized. The mature fruit is a Fig. 173— ^. style and stigma of

Vicia; B, same of Lathryus.

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 compound, the component parts being about one-half
the size of the grains in smooth peas. The seed coat is
27

4l8 BOTANY OF CROP PLANTS

thin; endosperm is wanting; the stored food is within the two
cotyledons. The cotyledons remain underground during
germination {hypogean germination), as in all cereals. This
type of germination is different from that in the bean and
squash, for example, in which the two cotyledons are raised
above ground, and for a time are food-making organs.
This sort of germination is called epigean.

Types of Peas. — There are but two well-recognized types
of Pisum: Garden peas and field peas. These are briefly
distinguished as follows:

Flowers white; seeds globular, uniformly yellowish, white or bluish green;
leaf axils green, unpigmented; comparatively tender Pisum sativum
(garden pea).

Flowers colored, usually purplish, red or lavender; seeds angular, gray-
brown, gray-green, gray-yellow or gray speckled with fine spots of various
colors; leaf axils pigmented; comparatively hardy Pisum salivuvi (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-
ing, (2) half-dwarf, and (3) dwarf varieties, and each of the
latter three groups into white-seeded and green-seeded sorts.
The sugar peas occur in both tall, half -dwarf, and dwarf
forms.

Period of Maturing. — As a general rule, the earliest sorts
of peas have smooth, round seeds, while the late sorts have

LEGUiMINOS.E

419

wrinkled seeds. SmouLh-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 \-arieties 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,
Xutt's Excelsior; C, main crop smooth pea, Marrowfat. (After Corbelt.)

are sometimes classified as to their time of maturing into
early, medium, and late or main crop. First,. of all, Alaska,
and American Wonder are examples otearl-' i-= ^'> ^ f^ans,
Advancer, and Pride of Market 01 u an, 'le

among late-maturing crops are such varieties as , ^one,
Telegraph and White Marrow Fat.

420

BOTANY OF CROP PLANTS

Field or Canadian Field Peas. — These have smooth, hard,
rather angular seeds. They are gray-green, gray-yellowish,
or gray dotted with purple, blue, rust red or brownish spots.
Garden peas are sometimes used as a field crop.

Fig. 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. {Afler Corbelt.)

Field peas are successfully grown only in those regions with
a cool gfewing season, in fact, they will withstand quite
\^Q^-7 T- .ci. "^-Tigh temperatures accompanied by high
re .aic_ to decidedly injurious. Excellent crops

are ^ - a-t 7,000 to 8,000 feet in the San Luis Valley of
Colorado.^ They do well on most types of soil.

LEGUMINOS^ 421

Peas and Mendelism. — 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
Mendel's Laws. He selected a number of differentiating (paired) characters
and observed their behavior when crossed with each other. In the brief
summary, here of his work, a number of characters of the genus Pisum are
brought out:

1. Round or roundish form of seed is dominant over angular or wrinkled
seed. That is, when a plant bearing roundish seeds is crossed with one bear-
ing angular or wrinkled seeds, the hybrid offspring bears seeds all of which are
roundish.

2. Yellow color of 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. j

Uses. — Peas in the green state are one of the most common
vegetables. They are also canned in large quantities. Field
peas are being grown as a companion crop, soiling crop,
green manure, and as a food for hogs, sheep, horses and
cattle. It is the practice in many places to pasture live
stock, particularly hogs and sheep, on field peas.

PHASEOLUS (Bean)

Description. — Representatives of this genus are annual or
perennial herbs or vines with pinnately three-foliate, rarely
one-foliate, leaves. The flowers occur in axillary racemes;
they vary in color : white, yellow, red, or purple. The calyx
is five-toothed or 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 keel is characteristically spirally
coiled (Fig. 176, A). The stamens are diadelphous (nine
and one). The ovary has a style longitudinally bearded, and

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.,
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 seedhng, 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
(Phaseolus vulgaris). A, spiral keel; B,
entire flower. X 2j^.

species.

A number of "beans" do not
fall within the genus Phaseolus, for example, broad bean {Vicia faba), soy
bean (Soja max), velvet bean (Mucuna utilis), asparagus or dolichos bean
{Vigna sesquipedalis) , cowpea or bean {Vigna sinensis),'' ]ack bean (Cana-
valia ensiformis), locust bean {Ceratonia siligna) and hyacinth bean, bonavist
or lablab {Dolichos lablab).

LEGUMINOS^

423

The adjuki bean (Pkaseolus 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. muUiflorus (scarlet runner bean).
Roots fibrous.

Seeds flat or flat-oval in cross-section, P. lunatus (Sieva and Lima beans).

Seeds mostly circular, but sometimes flat in cross-section, P. vulgaris
(kidney bean).

PHASEOLUS MULTIFLORUS (Scarlet Ruimer Bean, Dutch Case-
knife Bean, Flowering Bean, or Painted Lady)

These are perennials which usually have tall, climbing
stems and pinnately trifoHate leaves. The large and showy
flowers are scarlet (scarlet runner), or white (Dutch case-

FiG. 177. — Pistil of flower of common bean (Phaseolus vulgaris). (After
Knuth.)

knife), and form racemes. Pods are 3 to 6 inches long, and
curved; the seeds are large and plump, flattened or cylindric,
and vary in color.

The scarlet runner form is also known as the flowering bean
or painted lady, and is much used as an ornamental vine.
The Dutch case-knife form of this species — one with white

424 BOTANY OF CROP PLANTS

flowers — is grown for the edible beans. The Aroostook
bush Lima bean is considered by Tracy to be a bush form of
Phaseolus multiflorus. 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 multiflorus 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 cHmb-
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 Types 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 Relationship of Types of Lima Beans

Phaseoltis 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 oyate, Flat-seeded Limas.
Plants bush (Burpee's Dwarf Lima).
Plants^pole (King of the Garden).

LEGUMINOS^

425

^'^•/ '9.— Types of Lima beans. A, Potato Lima, pole'; B, Sieva type, pole;
C. large, flat Lxma. dwarf; D, Sieva type, dwarf. (^Modified after Corbelt.)

426 BOTANY OF CROP PLANTS

Seeds smaller; pods short and thick, with prominent tip; leaflets tapering,
long ovate. Potato Limas.
Plants bush (Dreer's Dwarf Lima).
Plants pole (Dreer's Improved).

PHASEOLUS VULGARIS (Kidney Bean)

These are annual plants, with 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 hush.\ These in turn each possess
green-podded and wax-podded sorts. The bush beans are
often grouped together under the variety P. vulgaris nanus.
Most of our common garden sorts are dwarf or bush beans. ^

The 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 Description.^ — The Vicias are chmbing or traihng
herbaceous vines. The leaves are pinnate, tendril-bearing,

^ For a detailed classification of American varieties of beans see Bull. 109,
Bureau of Plant Industry, by W. W. Tracy.

LEGUMINOS.E

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 arc attached
to the curved keel. The slamens
are diadelphous (nine and one),
or monadelphous below, and
have fihform filaments. The
sessile or stipitate ovary has
numerous ovules and a slender
style with a tuft or ring of hairs
at its summit (Fig. 173, A).
The pod is flat.

Geographical. — There are more than
100 species of Vicia, of wide geograph-
ical distribution. There are about 20
wild species in the United States.

Key to Important Species of Vria

Plants erect, smooth, or only slightly
hairy, seldom tendril-bearing; flowers
whitish with dark blue spots on each
wing, V.fabj (broad or Windsor bean).
Plants weak, usually hair>', tendril-
bearing; flowers purplish.
Leaves rounded at tip; flowers many,

in long one-sided racemes (I'ig.

182), V. villosa (hairy vetch).
Leaves truncate at tip; flowers few,

usually two in each leaf axil, V.

saliva (vetch).

427

Fk;. 180. — Types of bean seeds.
I, Broad Windsor; 2, While
Narrow Field; 3, Dutch Case
Knife Pole; 4, White Dutch Run-
ner Pole; 5, Grenells Stringless
Green Pod; 6, Lohk Yellow Si.x
Weeks; 7, Lohk White Pule Lima;
8. Powell's Prolific Pole; 9, Dreer's
Pole Lima; 10, Florida Butter
Pole Lima; ir. Yellow Cranberry
Bush; 12, Horticultural Wax;
1,3, Red Mexican; 14. French
Kidney. (Modifial after Tracy.
U. :S. Dcpi. Agri.)

428

BOTANY OF CROP PLANTS

Less Commoa Species.- -There are a number of other Vicia spp. that arc
cultivated to some extent, as follows: Narrow-leaved vetch (Vicia angustijolia)
is a native of the eastern United States, and is grown somewhat in Georgia

Fio. i.Si. — Broad or Windsor bean (,\

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
atro purpurea) resembles hairy vetch from which it differs, however, in being
smooth. It is cultivated on the Pacific Coast and in the South. Scarlet

LEGUMINOSiE 429

vetch (Vicia fulgens) , Narhonne vetch (yicia narbonnensis) and woolly podded
vetch (Vicia dasycarpa) are rather rare species, cultivated to a slight degree
on the Pacific Coast.

The term "vetch" is given to a number of plants, not belonging to the
genus Vicia, for example: Crown vetch {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 which branches freely.
The leaves are pinnately compound with about seven pairs
of leaflets, and a terminal tendril. Flowers occur singly or in
twos in the leaf axils; they are short peduncled, and reddish
purple (rarely white) in color. The flowers are cross-fer-
tiHzed. 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.

43 O 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 hght
soil. It is intolerant of a poorly drained soil. The poorer
soils of the East, deficient in hme, 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 VILLOSA (Hairy, Hungarian, Russian, Siberian, or Villous Vetch)

Hairy vetch (Fig. 182) is an annual or biennial, hairy plant
naturally suited to cool temperate regions. The plants may
grow to a length of 12 feet or more, but seldom to any consid-
erable height on account of the weak stems. There is an ex-
tensive and deep root system which in the early stages of
growth, particularly, constitutes a large proportion of the total
weight of the plant. There are five to eight pairs of leaflets,
and many (about thirty) violet-blue, rarely white, flowers in
one-sided racemes. Cross-fertiHzation is necessary for the
normal production of seeds. Bees are chief agents in the
dissemination of pollen. The pods are smooth, pale in color,
and contain two to eight small, globular black seeds. The
cotyledons remain underground at germination, as is the
case in the common garden and field pea. Hairy vetch is a

LEGUMINOSvE

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.

Hot summer weather is \ery harmful to its growth. It is
frequently planted on light, sand\- soils, where it nKi\- l)c
plowed under as a green manure.

432 BOTANY OF CROP PLANTS

The plant has a variety of uses: hay, pasturage, cover
crop, silage, and green manure. It is usually cut for hay
about the time the first pods are full grown. The quality
of the hay decreases after this period.

LATHYRUS (Vetching, WUd Pea)

This genus resembles Vicla. 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 Lalhyrus, natives of the
Northern Hemisphere and of South America. There are
numerous wild sorts in the United States. The two most
common species are Lalhyrus odoratus, the common sweet
pea, and Lalhyrus lalifolius, the everlasting or perennial pea.
Lalhyrus odoralus is an annual, bearing two to four (lowers
on a [)eduncle, and pods 4 to 5 inches long. The following
[.alhyrus species are of forage value and are now planted to
some extent in this country: L. lingilanus (Tangier pea),
L. cicera (flat-podded pea) and L. ochrus (ochrus).

TRIFOLIUM (CIov.m)

Generic Description. — Representatives of this group are
annual (crimson clover) or perennial (white clover) herbs
with palmately trifoliate (hence the name, Trijolium) 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
slamens are diadelphous (nijie and one). The ovary is sessile
or stipitate, and few-ovuled. The pods arc small, mem-
branaceous, mostly one-seeded (rarely more), indehiscent or
opening circularly. The seeds are small and kidney-shaped.

LEGUMINOS.E 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 Principai- Species of Trifolium

Flowers in spike-like heads, much longer than thick, T. incarnatum

(crimson or scarlet clover).
Flowers in globular or ovoid heads.

Corolla white or yellowish- white, sometimes touched with pink; stems

creeping, T. repens (white clover).
Corolla red, red-purple, or rose-colored; stems erect or nearly so.

Flowers pedicelled; stipules acuminate (Fig, 183, A), T. hybridum (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, trifoliate leaves
have inversely heart-shaped or notched leaflets and narrow,
membranous stipules. The inflorescence is a head and is
borne on a long flower stalk which arises in the leaf axils.
The flowers are small, fragrant, and white or pinkish. They
are erect at first, but become deflexed when mature. The
visitation of insects is necessary for the production of a
good crop of seed. The small pods are usually four-seeded.
The seeds vary a great deal in their longevity. Germination
of so-called "hard seeds" may be delayed several years in
the soil. Such seeds usually show up in germination tests.

434 BOTANY OF CROP PLANTS

Geographical, and Uses. — White clover has become dis-
tributed throughout the greater part of temperate North
America, Europe, and Asia. It is common in lawns, pas-
tures, and meadows, and is an important ingredient of lawn
grass mixtures. The only distinct agricultural variety is
Ladino clover (Trifolium repens latum). It is larger than
ordinary white clover, and less resistant to cold.

Environmental Relations. — White clover will withstand
greater temperature extremes than either red clover or alsike
clover. It is naturally suited to cool, moist regions. It is
more tolerant of shade than red and alsike clovers.

TRIFOLIUM HYBRIDUM (Alsike, Alsatian, or Swedish clover)

Description. — Alsike is an erect, branching, rather stout,
almost glabrous perennial, i to 3 feet tall. Its hfe 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. 1 83, 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 viabiHty rapidly after the second year.

Geographical, and Uses.- — Alsike clover is a native of
Europe. . It has been introduced into this country for agri-
cultural purposes and has escaped from cultivation, often
being found in fields and waste places. It is not a hybrid
between white clover and red clover, as formerly thought.
The plant is grown in the same manner and for the same
purposes as red clover. The plant is very hardy, more so
than red clover, and is quite frequently mixed with timothy

LEGUMINOS^

for planting at high altitudes and latitudes,
a honey plant.

435
It is prized as

TRIFOLIUM INCARNATUM (Crimson, Scarlet, or Italian Clover)

Description.— This is an erect, soft-hairy annual, 6 to
36 inches high. The leaves are long petioled; the stipules
are broad and with dark purple margins; the leaflets are

Fig. 183. — A, stipules of alsike clover (Trifolium hybridum); B, leaf of
yellow sweet clover (Melilotus alba) ; C, leaf of crimson clover (T. incarnatum) ;
D, leaf of common red clover (T. pratense); E, leaf of alfalfa (Medicago
sativa) .

almost sessile, and obovate or obcordate. The inflorescence
is a terminal, dense, elongated, spike-Hke head (Fig. 184).
The flowers are bright crimson (rarely white, yellow, rose or
variegated) and showy. The seed is shiny when fresh and
pinkish in color.

436 BOTANY OF CROP 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 or Purple Clover)

Habit, Stems and Roots. — This is a perennial plant, more
or less hairy, branching, decumbent or erect, 6 to 24 inches
tall, rising from the crown. The hfe period is a varietal
character. The average is about three years. It develops
from a strong tap root which possesses an extensive system
of laterals. The tap root reaches a depth of 3 or 6 feet.
It draws moisture and mineral nutrients from the lower soil
layers. In general there is about i pound of root to 2 pounds
of plant above ground. This means that the clover crop
leaves considerable organic matter in the soil.

Leaves. — The leaves are of the clover type, with hairy-
margined leaflets and large conspicuously purple-veined
stipules. The leaflets often bear a pale spot in the center.

Inflorescence and Flowers. — The' termmal ' inflorescences
are ovate (Fig. 184). Each inflorescence has from 35 to 150
purple-rose flowers. The second crop usually has more flowers

LEGUMINOS/E 437

pcrheatl than Ihc lirst crop, l^hij Jlowcrs arc of Ihc ordinary
pea type, except that the petals are united at their bases and
to the staminal tube to form a corolla-tube about 3^2 i^^ch
long.

(Trifiilium incur iiatuin),
er (T. pralcnse), 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. Lifertile ovules are ciuite com-

438

BOTANY OF CROP PLANTS

mon in red ckn-er, the larger percentage usually being in
the first crop. I'liis is probably one of the chief reasons why
the second cro[) 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 abo\e for the
relatively hght yield of seed in the first croj),
it is claimed that pollinating insects are not
abundant enough, and that the plant is occu-
pied with the production of new shoots rather
than reproductive activity. In general, a
rank-growing plant is not a good seed producer.
When the capsule is mature, the stylar end
separates from the basal part by an irregular
transverse line. The upper part of the cap-
sule, together with the style, comes off as a
lid (Fig. 185), and the single seed escapes. The seeds are
kidney-shaped, and yelhnv, 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 bundjle-
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 efiicient poUinators. When the bumble-
bee lights on the clover head and inserts its proboscis into
the staminal tube, its weight i)re.sses down on the keel and

Fig.
Fruit of red
clover (Trifo-
lium pratense),
much enlarged.

LEOUMiNos.ii: 439

wings of the flowcM*, from which nectar is being taken, thus
forcing out the stiuma 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. — Tlu; species is ;i native of Eurasia. It has become natural-
ized in the United States, occurring commonly in the fields and meadows
throughout most of our area.

Environmental Relations.— Red clover attains its best
growth in humid sections of the country, and where the
summer and winter temperatures are not extreme. Un-
like alfalfa, dry atmospheric conditions arc detrimental to
red clover; but like alfalfa it requires lime in the soil. More-
over, it is intolerant of a [)()()rly 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 Trijolium pratcnsc; as
compared with the latter, mammoth clover matures later,
has a more highly branching tap root, longer pedicels, and
solid stems. It is known as Trijolium pratcnse pcrcnne.

Uses. — Common red clover is one of our most prized
forage and hay cro{)s; 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 Ave times that of alfalfa. It is adapted to
the humid sections of the country. The highest percentage
of digestible substances occurs in the plant just, before full
bloom. The plant soon becomes tough and fibrous after
the blooming period.

440

BOTANY OF CROP PLANTS

Fi<i 18O.--A viguiMUo aU.iii.i plant sli.r.vuife; the "cruv.':!" from which
arise the numerous shoots. {After Ileadden, Colo. Agr. Exp. Sla.)

LEGUMINOS^

441

TRIFOLroM 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
the petiole, and the. leaflets com-
monly dentate, pinnately veined,
with the veins terminating in the teeth. The flowers are
small, yellow or violet, in axillary heads or racemes. The
calyx teeth are short, and about equal in length. The
petals are free from the staminal tube; the standard is
obovate or oblong, the wings oblong, and the keel short and
obtuse. The stamens are diadelphous (nine and one) . The

Fig. 187. — Seed and pod
of alfalfa (Medicago sativa).
X 5-

442 BOTANY or CROP PLANTS

ovary is sessile or short-stipitate, and several- or rarely one-
ovuled; it has a subulate (awl-shaped), and smooth style.
The pods (Fig. 187) are curved or spirally twisted, veiny or
spiny, and indehiscent.

Geographical. — There are a number of species of Medi-
cago, all of which are native to the eastern hemisphere. They
naturally range from Eastern Asia to Southern Africa.
There are seven perennial species of Medicago, and about 37^
annual species, one of which, yellow trefoil (Medicago lupu-
lina), has a biennial or possibly perennial form: The non-
perennial species are commonly known as "bur clovers."
They will grow naturally as winter annuals.

Key to Peincipal Species of Medicago

Perennial, erect-growing plants; flowers violet, Medicago saliva (alfalfa).
Annual, low-growing plants; flowers yellow.

Pods kidney-shaped, without spines, Medicago lupulina (hop clover).
Pods cylindrical, with spines.

Stems pubescent; pods 33^^ to 5 millimeters diameter; purple spot in
center of each leaflet; two to eight seeds in each pod, Medicago arabica
(spotted bur clover).
Stems glabrous, pods 7 to 10 millimeters diameter; no purple spot in
center of each leaflet; three to five seeds in each pod, Medicago
hispida (toothed bur clover).

MEDICAGO SATIVA (Alfalfa, Lucerne)

Roots. — Alfalfa is a deep feeder. The young plant usually
sends down a single tap root. As a rule, this takes a straight
downward course. Comparatively few side roots are given
off. Usually, these are below the depth of 4 feet. Headden
found in a plant only nine months old, that the young roots
had extended to a depth of over 9 feet. Ordinarily the weight
of roots exceeds weight of top.

Stems. — Alfalfa is an ascending or erect perennial. Its
life period is dependent upon environmental conditions and

LEGUMINOS^ 443

the variety. The average life is from five to seven years.
Fields 20 to 25 years old are found in the semi-arid sections.
At or near the ground level, is a short, compact stem (crown)
from which the numerous (20 to 50) branches arise (Fig. 186).
Bhnn has shown that there is a well-defined relationship be-
tween the nature of the crown and hardiness. Non-hardy
types of alfalfa have an upright-growing crown with but few
buds and shoots developed below the soil surface. The crown
of hardy types is more spreading and the numerous buds and
shoots come from below the soil surface. Hence in the latter
case, the buds and young shoots are protected by the soil
from winter freezing. These hardy types are Grimm and
Baltic strains. The stems of alfalfa are rather slender and
freely branching. Common alfalfa has no rootstocks.
Some forms of Medicago falcata possess them, however, and
they also occasionally appear in some variegated types.

"Cuttings" of Alfalfa. — The number of "cuttings" of
alfalfa depends upon the length of the growing season, and
the water supply. Three cuttings are usually made through-
out most of the alfalfa-growing regions of the United States.
In the Imperial Valley, California, ordinary alfalfa has
yielded as many as nine cuttings in a year. This practice
indicates that alfalfa has the capacity of sending up numerous
shoots from the crown. The shoots of a second or third
crop begin to appear about the time the plant is coming into
bloom, and it is the usual practice to cut the crop at this
time, so that the food supply that would normally go into
developing fruit and seed, is diverted to the young growing
shoots of the succeeding crop. Furthermore, the leaves are
richest in nutritive substances when the plant is in bloom.
The leaves contain about 80 per cent, of the protein in the
plant, hence methods of harvesting should look toward the
prevention of their loss. The different cuttings of alfalfa

444 BOTANY OF CROP PLANTS

vary somewhat in quality and chemical composition. How-
ever, more data are needed to determine the relative feeding
value of the different cuttings.

The alfalfa plant is a heavy feeder. According to Ames
and Boltz, a 3-ton yield of alfalfa hay contains 163 pounds of
nitrogen, 17 pounds of phosphorus, 99 pounds of potassium,
and 90 pounds of calcium.

Leaves. — The alternately arranged leaves are trifoliate
(Fig. 183, E). They are oblong in general outline and sharply
toothed along the margin; the tip is terminated by a pro-
jecting midrib. The stipules are prominent.

Inflorescense. — This is a dense raceme springing from the
axils of the branches.

Flowers. — The ordinary color of the flower is purple or
violet, but in variegated types, may be blue, green, or yellow.
The calyx teeth are longer than the tube of the calyx. The
standard is somewhat longer than the wings, which in turn
surpass the keel. The staminal tube is held in a state of
tension by two opposite lateral projections on the inside of
the keel (Fig. 188).

Pollination (Fig. 188). — Alfalfa possesses a mechanism for
the explosive dispersal of its pollen. When the edges of the
keel are spread apart, the staminal tube is released, and both
the pistil and stamens snap up against the standard. The
pollen is scattered in this process. The process is called
"tripping." Alfalfa flowers are usually tripped by visiting
insects, chiefly bumblebees and leaf-cutting bees {Mega-
chile). The weight of an insect may be sufiicient 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

LEGITMINOS^

445

"automatic" tripping. Humidity and temperature condi-
tions are probable causative factors in automatic tripping.
Both . self- and cross-pollination are effective in alfalfa.

tripped

Fig. i88. — 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. Deft. Agri.)

Self-pollination usually results from automatic tripping.
It is known that good seed crops are produced in regions
where tripping insects are scarce. However, the number

446 BOTANY OF CROP PLANTS

of pods set and the number of seeds per pod are increased
if cross-pollination (xenogamy) is accomplished.

Factors Affecting Seed Production. — As has been indi-
cated, cross-pollination results in a greater crop of seed than
self-pollination. An abundance of tripping insects may
increase considerably the seed output; however, good seed
crops occur in regions where tripping insects are scarce.
Seed production is usually Hght in humid sections of the
coimtry. Moreover, too much irrigation water appHed
during the flowering period is detrimental to seed production.
The heaviest yields of alfalfa seed occur in the arid sections
of Kansas, Colorado, Utah and Idaho. Isolated plants
invariably produce a greater crop of seed than those in a
thick stand. The sun's heat favors automatic tripping.

Martin finds that the setting of seed pods in alfalfa is
largely dependent upon the proper functioning of the pollen.
The pollen grains require a certain amount of water to germi-
nate. When a pollen grain comes to the stigma, the amount
of water it finds there depends upon the moisture delivery
of the stigma and the moisture of the air. The supply of
water for germination of the pollen grains may be changed
by increasing the water in the soil, or the atmospheric
humidity about the plant.

Fruit. — This is an indehiscent legume, coiled two or three
times (Fig. 187). There are one to eight seeds in each pod;
they are kidney-shaped, and about ^ inch long. The seeds
retain their viabihty for many years.

Germination and Seedling.^ — The young seedling consists
of two short cotyledon?, a hypocotyl, and a tap root. The
first foHage leaf is simple, while the second, third, and all
others are trifoliate. There is soon formed an erect stem
with but few branches; hence the first growth looks thin.
However, there spring up later numerous branches from

LEGUMINOS^ 447

the lowermost nodes and from the axils of the cotyledons.
The result is a well-developed "crown."

Geographical. — Common alfalfa is a native of temperate western Asia. The
original home is probably from northern India to the Mediterranean region.
It is now being cultivated in many parts of the world, and wherever so culti-
vated, frequently escapes and becomes a ruderal.

Types of Alfalfa. — Medicago saliva is now quite generally
considered to be an heterogeneous species, made up of many
strains, varieties, and even subspecies. Westgate holds that
some of our hardy strains of alfalfa (Grimm, for example)
owe their hardiness to the possession of a small percentage
of the "blood" of the hardy yellow-flowered or sickle alfalfa
(Medicago falcata). Numerous forms of alfalfa arise where
ordinary alfalfa {M. saliva) and yellow-flowered alfalfa (M.
falcala) 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. saliva and M. falcala; others
consider it to be a distinct species. Sand lucerne has flower?
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

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 under 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 sHghtly longer, and the floral bract is
"longer than either calyx teeth or calyx tube.

Environmental Relations. — Alfalfa is able to withstand
high temperatures if the air is dry, but high temperatures
accompanied by a humid air are decidedly injurious. For
this reason, it is particulary well adapted to the semi-arid
sections of the United States, where it is grown both on irri-
gated and non-irrigated land. Its resistance to low temper-
atures is a varietal characteristic, and also somewhat
dependent upon cultural operations. Grimm and Baltic
types are less Hable 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).

„ Water

Crop ' 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

LEGUMTNOS.E 449

In s[)ile 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 sufTers if soil drainage
is not good. The [)lant rec[uires lime in the soil. The soil
type has considerable influence u[)on 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
typicall}' de\-el()[)ed.

Uses and Production.- -Alfalfa is the most imi)()rtant hay
crop ''n the Western States. The total number of acres in
allall'a in the United States, 1909, was 4,707, £46; of this
number, the Western States furnished 4,523,513 acres.
The live leading States, 1909, named in the order of their
alfalfa [)r()duction were Kansas, Nebraska, Colorado, Cali-
fornia and Idaho.

MEDICAGO LUPULINA (Hop Clover, Black Medic, Yellow Trefoil)

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 obo\'ate, oval or orbicular, denticulate or
crenulate leallets. The jlowers are small, yellow, in den.se,
oblong or cylindrical heads. The pods are black, curved,
strongly veined, and one-seeded.

The plant is a native of Eurasia. It is now found through-
out the greater part of the United States and other temperate
regions where it occurs in fields and waste places.' It is
sometimes [)lanted on poor soil, and has some promise as
a green manure.

MEDICAGO ARABICA (Spotted Bur Clover)

This is a smooth annual j)lanL with procumbent stems.
The Iciilcls have a dark purpK' spot in the center. The pods

4SO

BOTANY OF CROP PLANTS

Fig. 189. — Pods of 10 species of Medicago. Top row, M. arabica and M.
hispida denticulata; second row, M. hispida confims"*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 Kicker, U. S. Dept. of Agr.)

LEGUMINOS/E

451

(Fig. 189) are in long clusters, twisted into three to live
spirals, and the edges bear numerous grooved spines which
interlock. The seeds are kidney-shaped, and about 2)^ milli-
meters long. Medicago arahica inermis is a spineless-podded
form.

Fk;. 190.— Toothed bur clover ( M

Spollrd bur clover is a native of Europe and Western
.\sia. It is introduced into the United States and occurs on
the Atlantic, Gulf, and California coasts. It is being used
as a [)aslurage crop.

452 BOTANY OF CROP PLANTS

MEDICAGO HISPIDA (Toothed Bur Clover)

Toothed bur clover (Fig. 190) is a smooth, annual plant
with decumbent leaves. The leajlds often have small whitish
and dark red spots scattered over the surface, which disap-
pear with age. T\iQfloivcrs 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 Jiisplda reticulala and M. hispida confmis
are forms with spineless pods. Toothed bur clover, Medi-
cago hispida dcnliculata, is native to the northern iVIediter-
ranean region. It is the most common bur clover grown in
California. It finds some use as a pasture, hay, cover and
green-manure crop.

In addition to the two species of bur clover given above,
there are about 35 species that are not cultivated to an\-
extent. They are all native to the Mediterranean region.
.■\11 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 m 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-Ukc 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

LF.GUMINOS/E

453

germinate the first season. This results from the i)ro(kiction
of some "hard seeds."

There are 15 to 20 species of sweet clover, natives of
Europe, Africa, and Asia. They are known by different
names, such as wild alfalfa, melilot, giant clover, Bokhara,
and sweet clover.

-Leaves and inflorescence of white sweet clover (Melilotus alba) nn
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,

454 BOTANY OF CROP PLANTS

yellow sweet clover. Several other species of Mclilotus
have been used agriculturally to some extent; among such
are M. indica ("sour clover"), M. altissima, M. gracilis,
and M . speciosa.

The characters of the two most im[)ortant species are
arranged in parallel rows for purposes of comparison.

.1/. alba M. officinalis

Cununonly biennial. Commonly annual, sometimes bicn-

Flowers white. nial.

Standard slightly longer than wings. Flowers yellow.
I'ofls pvoid, 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 have thick, oblong, finely toothed leaflets
which are narrowed at the base, and truncate, notched or
rounded at the apex. The racemes are numerous, slender.
and often one-sided. The flowers are white and ha\e 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 |)receding. It
does not grow so tall, however, is less common, and has

LEGUMINOS/E 455

yellow flowers. It blooms somewhat earlier than the white
sweet clover arid is more commonly annual in its habit than
biennial. It is a native of Eurasia and, Hke the preceding
species, has become naturalized in this coimtry, being widely
distributed as a ruderal throughout both the Northern and
Southern States.

Environmental Relations. — The sweet clovers thrive in
both semi-arid and humid climates, and upon all types of
soils — heavy and light, rich and poor, well-drained and illy-
drained. They are also drought-resistant. It is being intro-
duced where, for any reason, alfalfa and clover have failed.

Uses of Sweet Clovers. — ^Like other legumes, sweet clover
supports nodules of bacteria on its roots. In fact, it is
nearly as valuable as alfalfa to plow under as a green manure
to renew the soil. It makes good hay when properly
handled, and for pasturage purposes it has considerable
value. As a forage crop, it can be utilized where alfalfa
or red clover cannot be grown successfully. The plant
becomes coarse and unpalatable soon after blooming, and
hence it must be cut before this stage. The plants possess
a bitter principle, cumarin, which may cause an animal to
reject them as food at first, but usually the animal becomes
accustomed to them.

White sweet clover is much larger and more vigorous than
yellow, and consequently is the one recommended for
cultivation.

SOJA (Soy Bean)

Generic Description.^ — The soy beans are prostrate or
erect herbs with pinnately three-, rarely five- or seven-, foliate
leaves. The flowers are in short axillary racemes, and are
purple or whitish. The pods are linear or falcate, and two-
valved. The seeds are globular and pea-like.

456

BOTANY OF CROP PLANTS

There are between 15 and 20 species of Soja, natives of
tropical Asia, Africa, and Australia. There is only one
species of any economic importance. This is Soja max.

SOJA MAX (Soy Bean, Soja Bean, Coflfee Bean)

Description. — This is an erect, bushy appearing, hairy
annual, varying from i3^ 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.
The flowers are seK-pollinated
as a rule, and are completely
self-fertile. Occasional cross-fertiUzation occurs in the field
when varieties are planted very close together. The pods
are from i to 23^ inches long, yellowish or brown, and
covered with short bristly hairs. As many as 300 to 400
pods have been found on one plant, and each pod usually
contains two or three seeds. In fact, the soy bean is the
greatest seed producer of any legume grown in temperate

Fig. 192. — Soy bean (Soja max).
{After Piper.)

LEGUMINOS^ •. 457

climates. The seeds vary greatly in color; there are shades
of cream, white, yellow, green, brown, and black; they also
vary in shape from globose to elliptical. Under the most
favorable conditions, soy bean seeds do not retain their
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 chmates, 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
fertihzer. 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 utiUzed to
make a so-called soy-bean milk, which is valued for cooking

* Data from the U. S. Dept. of Agri. Bureau of Chemistry.

4S8 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 soiHng 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 1^ean {Phaseolus
vulgaris), however, mainly in that the keel of the corolla is
short and merely incurved rather than spirally coiled. The
leaves are pinnately trifohate. The flowers are yellowish or
purpHsh, in head-shaped or racemose inflorescences at the
ends of long pedmicles; these arise in the axils of leaves.
The calyx is five-toothed. The stamens are diadelphous
(nine and one). The ovary is sessile, many-ovuled, and
bears a style that is bearded along the inner side. The
pods are linear, straight or slightly curved, and two-valved.
The seeds are much like the common kidney bean in shape
(Fig. 193).

All the Vigna spp. (''Vignas") are natives of warm and
tropical regions, and consequently they have been most
successfully cultivated in the Southern States.

Species. — There are but three cultivated species of
"Vignas": Vigna sesquipedalis (asparagus bean), Vigna
catjang (catjang), and Vigna sinensis (cowpea). The as-
paragus bean has pendant pods i to 3 feet long, and kidney-

FiG. 193. — Seeds of i6 varieties of Vigna showing range in variation of
shape, size and color. The top three rows are catjangs (Vigna catjang), the
bottom two rows are asparagus beans (Vigna sesquipedalis), and the others are
cowpeas (Vigna sinensis). (,After Piper, U. S. Dept. of Agri.)

LEGUMINOS.E

459

B 2 m

^ 3 ^

^^^

^^•,

(♦

^ e ^

^ 7 ^

r^^^

1PK

tP^

^i^ /cf^

W) // ^

«^

*^w^

^^^ /2 "^^

^^^^

i^^^^^

•"/J "-^

«*

^ /^^

«^

?r^

W^^^^

fV^

w»

f^/^^^

fm,

Fin. rov

460

BOTANY OF CROP PLANTS

shaped seeds 8 to 12 millimeters l(jng. In catjang, the pcjds
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.

Fir.. 194. — .1, flowers and fruit of catjang (Vigna catjaiiK')". H- flower
fruit of cowpea (Vigna sinensis). (After U. S. Dcpt. of Aari.)

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 feet of soil. The varieties vary
in habit from prostrate traihng herbs to tall and half-bushy
forms. The cowpea has an indeterminate growth, that is,
it continues to grow indehnitely, providing environmental
conditions are favorable. As in the majority of plants
vegetative growth is favored by an abundance of water and

LEGUMINOSiE

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 aroimd
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.

Pig. 195.-

-Cowpea (Vigna sinensis).
{After Piper.)

462 BOTANY OF CROP PLANTS

Environmental Relations. — The cowpea is of tropical
origin, and, hence, is adapted to those sections of the country
with warm summers; in fact, it requires more heat than
corn, and 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 locaHties as a catch crop or as a green
manure, and is adapted to rotation in a cropping system.
The seeds are fed to poultry, and are also recommended as
a food for man. The roasted seeds are a substitute for
coffee.

ARACHIS HYPOGGEA (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 "nmning types," or upright and bushy, as in the "bush
types." The stems are thick, angular, branching, and hairy.

Leaves. — The leaves are pinnately compound, usually
with two pairs of subsessile, entire leaflets, and no tendrils;
the elongated stipules are adnate to the petiole base.

Flowers (Fig. 197). — The flowers are axillary, sessile,
and orange-yellow in color. There are two sorts of flowers
on the plant, sterile and fertile. Sterile flowers are most
numerous in the upper axils, on long, slender pedicels; they
have monadelphous stamens (nine united, one abortive)
and a minute abortive ovary. The calyx tube is long and
slender, and bears on its rim the calyx lobes, corolla, and

LEGUMINOS^ 463

stamens; the four superior 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, 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. — Peanut (Arachis hypogaea). {After Jones.)

Development of Fruit (Fig. 196) .—After the ovules are fer-
tilized, the stamens and corolla fall off; then the flower stalk
elongates, bends downward, and carries the developing
ovary several inches into the ground. Once buried, the
ovary ripens. If the 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 "shell" of
the "peanut" is the pericarp; the thin skin that surrounds
each seed or pea ("nut") is the testa. The cotyledons are
large, and rich in stored food.

464

BOTANY OF CROP PLANTS

standard

Types. — The American varieties may be divided into two
large groups: (i) large-podded and (2) small-podded. Each
of these is further subdivided into "bush" or "bunch,"
and "running" types. Well-known varieties in this country

are Virginia Bunch, Virginia
Runner, Carolina, Spanish,
and Tennessee Red. The
last-named variety has red-
skinned seeds. The nuts in
the Spanish variety are
smaller than those of the
other types. Large-podded
varieties are sometimes
termed "Jumbos."

Environmental Relations.
— The peanut is a tropical
plant. Consequently, it is
raised where the growing
season is long, and warm.
It succeeds best south of the
36° latitude.

The plant is favored by
ample sunshine and moder-
ate rainfall. It is grown
successfully on both sandy
and clay soils, although the
former are preferred, espe-
cially when the pods are grown for the market and a bright,
clean appearance is desired.

Uses.— Peanuts are largely used in the roasted state as
a human food. Peanut butter has become a very popular
food article. One bushel of first-class nuts will yield about
12 pounds of butter. Oil, salted peanuts and peanut candies

Fig. 197. — Flower of peanut (Arachis
hypogaea). (After Tanberl.)

LEGUMINOSiE 465

arc other products. The nuts (^'goobers") are fed to hogs,
or the animals arc turned iti to pasture on both the vines
and nuts. Pcanul 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 im[)orted
1,332,108 gallons of the oil during 1914.

LESS IMPORTANT LEGUMES

The following list includes several of the less ini[)()rtant
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 llowers.
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 a.\ils 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
iloes well on thin uplands.

Onobrychis viciaefolia (Sainfoin). — A deep-rooted perennial witii erect
stems, odd-pinnate leaves, si.x 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 .\merica from Asia, but it is little
grown here. It is adapted to dry barren lands that are not suited to clovers
anil alfalfas. It has been grown with success on calcareous soils.

Ornithopus sativus (Serradella).~.\ low. branched annual, with pinnately
compound lea\es, and rose colored or purplish llowers in umbels. The pods
30

466

BOTANY OF CROP PLANTS

break into joints. The plant malces 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

jr arictimim)

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.

LEGUMINOSiE 467

Cicer arietinum (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 fcenum-gr cecum (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
Bartlett, G.: The Native and Cultivated Vicieae and Phaseoleas of Ohio.

Ohio Nat., 15: 393-404, 1914.
Beal, A. C: Evolution and Pollination of the Sweet Pea. Florist's Exch.,

32: 140-141, 1911.
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, 1911.
Blinn, Philo. : Alfalfa — the Relation of Type to Hardiness. Colo. Agr. Exp.

Sta. Bull. i8i: 1-16, 1911.
French, G. T. : Observations on Medicago lupulina L. Science, n. s., 2,

28: 127, 1908.
FucsKO, Mihaly: tJber die biologischen und entwickelungsgeschichtlichen

Verhaltnisse des Pericarps der Papilionaten. Ung. Bot. Bl., 8: 264-265,

1909.
Anatomic, 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: Uber die Wirkung der Selbstbestaubung bei den Papili-

onaceen. Naturw. Ztschr. Land-u. Forstw. Jahrg., 3, Heft 1: 1-16, 1905.
Martin, J. N.: Relation of Moisture to Seed Production in Alfalfa. Iowa

Agr. Exp. Sta. Research Bull. 23: 303-324, 1915.
McKee, Roland, and Ricker, P. L.: Non-perennial Medicagos: the Agro-
nomic Value and Botanical Relationship of the Species. U. S. Dept. Agr.

Bur. Plant Ind. Bull. 267: 1-36, 1913.
Oakley, R. A., and Garver, Samdel: Medico falcata, a Yellow- flowered

Alfafa. U. S., Dept. Agr. Bull. 428: 1-70, 1917.

468 BOTANY OE CROP PLANTS

Pammel, Edna C, and Clark, Clarissa: Studies in Variation of Red Clover.

Proc. la. Acad. Sci., 18: 47-53, 1911.
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.
Peenninger, Ues. : 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:

1-15- 1915-
The Soy Bean, with Special Reference to Its Utilization for Oil, Cake and

Other Products. U. S. Dept. Agr. Bull. 439: 1-20, 191 6.
Piper, C. V.: Agricultural Varieties of the Cowpea and Immediately Related

Species. U. S. Deot. Agr. Bur. Plant Ind. Bull. 229: 1-160, 1912.
Soja Max. Jour. Am. Soc. Agron., 6: 75-84, 1914.
Piper, C. V., Evans, Morgan W., McKee, Roland, and Morse, W. J.:

Alfalfa Seed Production; Pollination Studies. U. S. Dept. Agr. Bull. 75-

1-32, 1914.
Piper, C. V., and McKee, Roland: Vetches. U. S. Dept. Agr. Farmers'

Bull. 515: 1-28, 1912.
ScoriELD, Carl S.: The Botanical History and Classification of Alfalfa

U. S. Dept. Agr. Bur. Plant Ind. Bull. 131: 1-1-19, 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, 1912.
Westgate, J. M., Coe, H. S., Wiancko, A. T., Robbins, F. E., Hughes, H.

D., Pammel, L. H., and Martin, J. N.: Red-clover Seed Production:

Pollination Studies. U. S. Dept. Agr. Bull. 289: 1-31, 1915.
Wight, W. F.: The History of the Cowpea (Vigna unguiculata) and Its

Introduction into America. U. S. Dept. Agr. Bur. Plant Ind. Bull. 102:

43-59, 1907-
Winton, Kate, B.: Comparative Histology of Alfalfa and Clovers. Bot.

Gaz., 57: 53-63, 1914.

CHAPTER XXX
LINACEiE (Flax FamUy)

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 stems 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 corymb or cyme, 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 united at the base. The outer whorl of stamens
is wanting or staminodial. The pistil consists of a five-
celled ovary, each cell of which bears two ovules. The five
styles may be free, united to the stigmas, or united part way
from the base.

Fruit.— The flax fruit is a five-celled capsule with two seeds
in each cell; each cell is partially or completely divided into
two by a false partition between the two seeds, thus making
the capsule apparently ten-celled (Fig. 21).
469

470 BOTANY or 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-
mum. 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

LINACK/E

471

rigid, at the same time retaining considerable elasticity due
to the bast fibers.

Flax Fibers. — Three tissue areas arc recognizable in the
stem: i)ith, wood, and bark. The flax bark contains the
bast or llax fiber cells. These bast fibers give flax straw

its great financial value since they make up the part from
which linen is made. Each bast fiber is a single cell, 25 to
30 millimeters long, and cylindrical in shape.

Leaves, Inflorescence and Flowers.— The leaves are
narrow, entire, and blunt at the apex. The inflorescence

472 BOTANY OF CROP PLANTS

is loosely cymosc. The llowers vary in color from while to
deep blue. The same plant always bears llowers of the
same color. Yellow-flowered varieties are not found in
this species. The [)etals 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 freel\-,
whether associated with other flowers or not. Examination
of'^flax llowers_ 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 live fused carpels. The balls are divided into li\e
true ca\ities or locules by means of live true partitions (sei)ti)
extending from the wall (pericarp) to the axis. Each loculc
contains two seeds and is divided more or less incompletely
into two loculi by means of false septi. The seed balls are
yi inch or more in diameter. When fully ripe, they are
easily separated into parts at the points where the car[)els
are joined.

Seeds. — The seeds vary in length from \i to '- inch.
They are lenticular, compressed, and slightly longer than
wide. They have a very smooth, pohshed surface and vary
in color from yellow to dark brown. Light brown is the
standard color. A mucilaginous material which quick I \-
becomes sticky (viscid) in hot water is found tilling 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. ComnKju flax is a mitivc of Eiiropi;. IL is now widely tlis-
IribiiLcd over the world, hiring grown commercially in m;iny countries. Jndi;i
is a heavy producer of seed, and in Argentina it is grown extensively for oil.

LINAGES 473

Types and Varieties.— There are large-seeded and small-
seeded varieties. The large-seeded types are sometimes
known as Sicilian flax, and are grown almost entirely for
their seed, rather than fiber; there are both blue- and white-
flowered sorts. The small-seeded types are grown both for
fiber and seed; there are both blue- and white-flowered
varieties. The fiber flaxes have more slender stems, fewer
basal branches, and a more compact panicle than the seed
flaxes.

Uses.^ — Linseed Oil. — The manufacture of linseed oil is
carried on in manufacturing plants having investments of
millions of dollars. The seeds are crushed, heated to about
i65°F., placed in tanks or cylinders, and while hot, treated
with naphtha to extract the oil. From 30 to 39 per cent,
of the seed is oil. Linseed oil is used in the manufacture of
paints, patent leather and varnishes. Linoleum is a prepara-
tion of linseed oil which is hardened by treating with sulphur
chloride or by exposure to heated air. It is sometimes used
as a substitute for india-rubber. Oil cloth and other sorts
of floor cloth, are made by mixing ground cork with the
hardened linseed oil (linoleum), and pressing upon canvas.

Oil Cake and Oil Meal. — The residue from the crushed flax
seeds is known as oil cake. It is sold either as oil cake or
ground into a meal, 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 m this section. Flax fiber is also utilized
for making thread, carpet yarns, fishing lines, seine twines,
etc. It is also employed to some extent for upholstering,
for insulating cold-storage plants, refrigerator cars and ice

LINAGES 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 bundles. 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 pounded
by hand or bent by machinery, until the fiber is almost
entirely freed of other stem parts. The next treatment,
known as "scutching," consists in beating the fibers until any
fragments of bark or wood or course fibers, not removed in
the breaking process, are eliminated. Paddles, operated
by hand or by machinery, are used in the scutching process.
The fibers are sorted and baled, and kept in this form until
ready to be spun.

Production of Flax.— Most of the flax for fiber is grown in
the European countries. The United States is one of the
largest seed-producing countries but raises a 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.

CHAPTER XXXI

RUTACEiE (Rue Family)

Description. — This family is represented by trees, shrubs,
and herbs. The leaves are alternate or opposite, simple or
compound, exstipulate, and glandular-dotted. The glands,
which appear as translucent dots, are internal. They vary
somewhat in size and shape. The flowers (Figs. 200 and 201)
are soHtary or in small axillary or terminal cymes. The sepals
are four to five in number, biit 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.)

RUTACE^

477

Key to Important Genera of Rutace^"^

Leaves trifoliate, Ponciriis (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, Cilrics (orange, lemon, grapefruit, lime, etc.).

Fig. 201. — Sour orange (Citrus aurantium). A, flowering branch; B.
lengthwise section of flower; C, lengthwise section of fruit; D, seed. (After
Wossidlo.)

CITRUS (Citron, Lemon, Orange, etc.)
Habit, Roots. — Citrus species are aromatic, mostly thorny
shrubs or small trees with the spines disposed singly in the
leaf axils. The sweet orange tree is a surface feeder; almost
its entire root system is in the first i8 inches of soil. The
sour orange root system penetrates to a much greater depth.
The citrus plant is different from most plants in the total
absence of root hairs. Absorption is carried on by the fibrous
roots which are abundant and capable of rapid growth.
Leaves. — The leaves are glandular-dotted, winged-petio-

^Hume has been followed largely in the discussion of this group.

478 BOTANY OF CROP PLANTS

late, glaucous, leathery, evergreen, and 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 purpHsh-pink flowers are solitary,
or in small axillary or terminal cjnnes or panicles. The
flowers are hermaphroditic; the calyx is three- to six- toothed;
the corolla has four to eight separate thick segments (petals) ;
and there are 20 to 60 stamens, united at their bases to form
groups; the ovary possesses 8 to 75 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-fertiHzation, and more-
over, will not set fruit unless pollen is derived from certain
congenial varieties. Pollination may occur without the
visitation of insects. The time for complete fertihzation
after pollination varies from thirty hours in Satsuma oranges
to four weeks in trifoliate oranges. Parthenocarpic varieties
seldom bear viable pollen. In navel oranges there is no
pollen in the anthers at flowering time.

Fruit. — The fruit is a modified berry (hesperidium) ;
it is spherical or spheroidal and is made up of a thick,
leathery "rind" with numerous lysigenous oil glands, and a
juicy pulp composed of numerous stalked "juice sacks."

RUTACE.E 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
polyembryonic condition of citrus fruits is characteristic.
As many as thirteen seedlings from one seed have been noted.
Strasburger has shown that embryos of citrus seeds may be
derived from nucellar cells, as well as from fertilized ova.
He has designated such embryos as "adventitious." Hence,
in the polyembryonic seed, there are two sorts of embryos:
(i) those formed by the union of egg nucleus and sperm
nucleus, true sexual embryos; and (2) "adventitious"
embryos formed by vegetative growth. Obviously, the
seedlings from adventitious embryos may be used for propo-
gation with confidence that they will come true to the plant
which bore them. Early disintegration of embryo sacs
appears to be prevalent in citrus fruit. This may be one
cause, along with infertile pollen, of seedless fruits in this
group.

Geographical. — Citrus species are mostly natives of the 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 or 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).

480 BOTANY OF CROP PLANTS

Petals white both on the inside and outside.
Leaves wingless or narrowly winged.

Fruit small, i^ to 23^^ inches in diameter, its skin thin, C. auranlifolia

(lime).
Fruit large, its skin thick.
Tree small, 12 to 20 feet tall; skin of fruit easily removed, C. nobilis

(king orange).
Tree large, 20 to 40 feet high; skin of fruit not easily removed, C.
sinensis (common sweet orange).
Leaves broadly winged.

Fruit large, pale lemon-yellow when ripe, C. grandis (grapefruit, pomelo,

shaddock) .
Fruit medium-sized, orange-colored or reddish when ripe, C. auranlium
(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

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 dowers are axillary, usually solitary.

{[■'ruin Calif, .l.ijr. fix p.

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 fniit is about 3

482 BOTANY OF CROP PLANTS

inches long, light yellow when mature, its skm medium-
thick, the pulp abundant and acid, and the juice sacks long
and pointed. The fruit requires aljout nine months to
reach maturity.

Geographical.— The lemon is probably a native of India. It is cultivated
extensively in the Mediterranean region, and to a considerable extent in Cali-
fornia and Florida.

Colpr of Lemon Fruit. — ^Lemons are picked when they
reach a size demanded by the market, regardless of the
degree of maturity. Hence many of the lemons, when
picked, are dark green, and not the lemon-yellow of those
we buy in the market. Tlu- fruit is colored and ripened be-
fore shipment. If they arc not to be shipped for several
months, they are placed in storage houses ;where coloring
•s^rrd ripening goes on gradually. However,'it^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 w'ithin four to six days.

Uses.— Lemons, a re used in the home for lemonade, as an
ingredient in a number of prepared foods, as a stain-removej,
and as a bleaching agent. One of the chief uses of lenyjhs
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 rmd.
About 95 per cent, of the lemon oil produced is obtained from
the lemons b}- the sponge method, the remainder b}- the
machine method. There are two sponge methods, known as
the two-piece, and three-piece si)onge methods. Tn the former

RUTACE^ 483

method the lemons are cut by hand into two pieces, and the
pulp removed; the rinds are then thoroughly soaked in water,
and after standing for several hours, passed on to the spongers.
The apparatus of the sponger consists of a round stick about
I inch in diameter, placed across the top of an earthenware
bowl about 8 inches tall and the same in diameter, and
three sponges. A flat sponge is hung across the stick, upon
this another thicker sponge, and finally a third above this.
The third or upper sponge is cup-shaped; into this depres-
sion, the lemon rind is inserted. By main strength the
operator presses upon the sponge, repeating this pressure,
after turning the rind over several times. Only i pound of
oil is secured from 1,600 to 2,200 lemon halves. The three-
piece method differs but shghtly from the preceding.

CITRUS AURANTIFOLIA (Lime)

Description.— This is a small stragghng tree or shrub, with
numerous, small, very sharp thorns; the small leaves are
elliptic-oval, crenate, glossy-green, and its petioles are nar-
rowly, but distinctly, winged; the flowers are small, and
usually produced in clusters of 3 to 10; the petals are white
both above and below; the stamens range from 20 to 25;
the ovary commonly has about 10 locules; the fruit is small'
from i}i to 2i^ inches in diameter, oblong, or rounded-
oblong in outline, light yellow when ripe, its skin thin, the
pulp abundant, greenish and very acid, and the juice sacks
small, oval, and pointed.

Geographical.— The lime is a native of India and southeastern Asia. It is
cultivated in many tropical countries, and to some extent in Florida and the
Keys. The fruit is used in the making of "limeade."

"Limequat."— The "Hmequat" is a hybrid between a
kumquat and the Mexican lime.

484 BOTANY OF CROP PLANTS

CITRUS SINENSIS (Common or Sweet Orange)
Description. — The sweet orange tree is 25 to 40 feet high,
round-topped, and usually bears slender, flexible, blunt
spines; the leaves are oval or ovate-oblong, and the petioles
are narrowly winged, articulated both with the blade and
the twig; i\iQ, 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 quaHty and fine-grained. Blood oranges
have red pulp or white pulp streaked with red; the fruit
is of good quaHty. 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 sHght extent as a drug.

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 NOBHIS (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 floivers
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 fruil 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.— Ci7rw5 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 langelo which is a hybrid between the
tangerine and the Bowcn grapefruit. Citrus nohilis j^diV.
unshiu is the Satsuma or Unshiu orange. It is a small,
spineless, dwarf tree, and very hardy.

CITRUS GRANDIS (Grapefruit, Pomelo, Shaddock)

Description.— This species is a large tree, 20 to 40 feet in
height, with slender, flexible spines, if present; the leaves
are large, ovate, crcnate, broadly rounded at the base, and
the petioles are broadly winged and articulated; the flowers
are borne singly or in clusters of 2 to 20; the petals are white
both above and below; there are from 20 to 25 stamens, with
large linear anthers; the ovary has from 11 to 14 locules; the
fruit is very large, 4 to 6 inches in diameter, globose, oblate
or pear-shaped, pale lemon-yellow when ripe, its skin smooth.

486

BOTANY OF CROV PLANTS

the pulp peculiarly acid or sub-acid, and the juice sacks large
and spindle-shaped.

Fi.;. 204- r

A^r. l:xp. Slu

Geographical. — The species is a native of Polynesia and tiie Malay Archi
pclago. It is now grown in the United States.

RUTACE^ 487

Variety and Name. — The name grapefruit is the one that
this species is known by commercially. Shaddock is a horti-
cultural variety, the fruit of which is much larger than the
common grapefruit. It is a coarse, thick-skinned fruit, with
thick, leathery septa between the locules, and is of no com-
mercial importance. The name pomelo is now recognized by
most horticulturists. Grapefruit is a well-known breakfast
fruit.

CITRUS AURANTIUM (Sour or SeviUe 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 Jruit is
globose, orange-colored or reddish, rough, the pulp acid, and
the juice sacks small and spindle-shaped.

Geographical. — The sour orange is probably a native of southeastern Asia.
It is cultivated in the United States, being used as a stock on which to bud
other citrus fruits.

Other Species of Citrus. — Other Citrus species of less
commercial importance in the United States are C. mitis,
the Calamondin orange, C. ichangensis , Ichang lemon, and
C. hergamia, bergamot.

FORTUNELLA (Citrus) (Kumquat or Kinkan)

Description. — The kumquats are evergreen shrubs with
simple, glandular" leaves; the scented white flowers are single
or in clusters of three or four, and axillary; the early flowers
in the spring are usually without pistils; there are four times
as many stamens as petals; the ovary has three to seven cells,

488

BOTANY 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
iH inches in diameter, 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 commoh species of Fortunella
are F. margarita, the Oval or Nagami kumquat, and F.

RUTACEiE 489

japonica, the Round or Marumi kumquat. The former is
athornless shrub or small tree with oval fruit, the latter a
thorny shrub with globose fruit. F. crassifolia is the Meiwa
kumquat, and F. hindsii, the Hongkong wild kumquat.
The latter is considered by Swingle to be the wild stem form
of our Citrus species.

Uses. — The kumquats are shrubs grown as -ornamentals,
and also for their fruit, which is eaten raw and entire.

PONCmUS, (TrifoUate Orange)

Description. — The trifoliate orange is a low tree, seldom
over 15 feet high; the older branches are thorny, the thorns
being i to ij^ inches long, and flattened at the base; the
characteristic deciduous trifoliate leaves are composed of
thin, elliptical, crenate or dentate leaflets; t\iQ 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.

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., 1915.
Hood, S. C, and Russell, G. A.: The Production of Sweet-orange Oil and
a New Machine for Peeling Citrus Fruits. U. S. Dept. Agr. Bull. 399:
1-19, 1916.
Hume, H. Harold: Pomelos. Fla. Agr. Exp. Sta. Bull. 58: 385-421, 1901.
The Kumquats. Fla. Agr. Exp. Sta. Bull. 65: 555-566, 1902.
The Mandarin Orange Group. Fla. Agr. Exp. Sta. Bull. 66: 571-594. 1903-
Citrus Fruits and Their Culture. Orange Judd Co., 1913.
Ikeda, Tomochika: On the Parthenocarpy of Citrus fruits. Jour. Sci. Agr.

Soc. Tokyo, 63, 1904.
OsAWA, I.: Cytological and Experimental Studies in Citrus. Jour. Col. Agr.

Imp. Univ. Tokyo, 4: 83-116, 1912.
Strasburger, E.: tJber Polyembryonie. Jenaisch. Zeitsch. Naturwiss.,

12: 647-670, 1878.
Webber, H. J.: Complications in Citrus Hybridization Caused by Poly-
embryony. Science, n. s., 11: 308, 1900.

CHAPTER XXXII

VITACE^ (Grape Family)

Family Description.— Members of the grape family are
either climbers or erect shrubs with nodose joints. There is
an abundance of watery sap. The leaves are alternate and
petioled, either simple (Vitis)
or compound {Parthenocissus)
(Fig. 206). The inflores-
cence is commonly a panicle
(Vitis) or a cyme (Partheno-
cissus). The flowers (Fig.
210) are small, greenish,
perfect or polygamo-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. — Compounddigitate leaf
of Virginia creeper (Parthenocissus
quinquefolia).

492

BOTANY OF CROP PLANTS

Key to Important Genera

The three most important genera are Vitis (grape), Cissus (pepper
vine) and Parthenocissus (Virginia Creeper and American IvyJ . 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), Vitis (grape).
Petals separate, spreading, Cissus (pepper vine).
Leaves digitately compound, Parthenocissus (Virginia
creeper, American ivy).

VITIS (Grape)

Stems. — Grapes are climbing or woody
vines with tendrils. The stem is jointed.
The internodes have a large pith. In many

JP species there is a woody tissue (diaphragm)
at the nodes separating the pith; in others
this woody tissue is absent (Fig. 207). In
pruning the vines, the practice is to make
the cut through the nodes rather than through
the internodes; by cutting through an inter-
node, the pith shrinks, leaving a hollow in
which water may collect and rotting set in.
Grapes have a tendency to produce suckers
and water sprouts. The former arise from
below or near the surface of the ground and
should be removed. Water sprouts arise
from dormant buds above ground. They do
not produce fruit. If dormant buds de-
velop, producing these sterile shoots, it in-
dicates that there is not a sufficient number
of fruit buds to take care of all the sap
coming to aerial parts. Water sprouts should
be removed during winter pruning.

Tendrils, morphologically, are modified stems. This is

Fig. 207. — Two
types of grape
stems cut in me-
dian lengthwise
section. A, south-
ern fox grape
(Vitis rotundifo-
Ha) with pith con-
tinuous at the
nodes; B, old
world grape (V.
vinif era) with pith
interrupted at the
nodes. {After
Hedrick.)

VITACE/E

493

shown by the fact that they sometimes bear small leaves or
llowers. In the Fox grape (Fig. 2c8), there is either a tendril
or an inflorescence opposite each leaf. This continuity

Fig. 208. — Northern fox grupo (Vitis lahrusca).

is somewhat variable, however. In all other species, there
are two successive leaves with a tendril or inflorescence oppo-

494

BOTANY OF CROP PLANTS

Fig. 209. — Fruit-boaring slioot of river-bank: grape (Vitis riparia). (.I//1'
Hedrick.)

VITACE^ 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 until the end of the season. Vitis lahrusca 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 lahrusca, 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

4g6 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
^land

Fig. 2IO. — Grape flower, opening. X 20.

The flowers (Fig. 210) are hypogynous and regular. The
calyx consists of a narrow rim at the base of the flower. The
corolla has five united, greenish petals; in the bud, they form
a cap (Fig. 210) over the stamens and pistils. When the
flower opens, the petals become loosened at the base but
remain united by the tips. Stamens are five in number and

VITACE^ 497

there is an equal number of nectar glands between. The
one pistil is two-celled and two-ovuled. The fruit is a
berry.

Dorsey has cited marked variations in the flowers of the
genus Vitis: stamens may vary from three to nine; petals,
nectariferous glands, and carpels have a corresponding
numerical variation.

Opening of Flower and Pollination. — Flower Opening. —
The opening of the grape flower is indicated by the breaking
away of the petals at the base (Fig. 2 10). In some instances,
all the petals break away at about the same time; at other
times, one petal may initiate the. process, and be followed
by the others. The cap of 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

498 BOTANY OF CROP PLANTS

and pistillate." He finds all gradations between "pseudo-
staminate" and "pseudo-pistillate" forms among wild
species.

Grape Pollen .^ — In a study of grape pollen, Booth found
that self-sterile pollen differs from self-fertile pollen. In the
self-fertile form, the grain is surrounded by a mucilaginous
substance which causes them to stick together; the grain is
oblong in shape, symmetrical, and blunt at the ends. Self-
sterile pollen has no mucilaginous substance about it; it is
irregular in shape and more pointed at the ends. Self-
fertile and self-fertile pollen may be mixed in the same
variety. The degree of self-sterility or self-fertility seems
to vary with environmental conditions.

"Couloure" of Muscat Grape. — This valuable raisin grape
has a tendency to drop its blossoms without setting fruit.
This trouble is known as "couloure." It results from a lack
of fertiHzation. This is due to the fact that in this variety
stamens are shorter than the pistil, that the pollen has a
tendency to stick together in masses which makes its dis-
tribution less certain, and to the rather frequent development
of imperfect pollen grains. The difficulty is largely overcome
by planting, in the Muscat vineyard, varieties that produce
an abundance of viable pollen, and that blossom at the same
time as the Muscat. These varieties will furnish pollen for
fertilization of Muscat flowers.

Flowers in Wild Grapes. — Grapes in the native condition
differ from those in cultivation. The wild forms seldom bear
self-fertile perfect flowers. In these, there are just two sorts
of vines: (i) staminate, and (2) self-sterile hermaphrodite.
There are no self-fertile hermaphrodites. The staminate
flowers have abortive pistils, and the so-called pistillate forms
retain their stamens, but they are abortive.

VITACEJE 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 vsdthout diaphragms (Fig. 207, A) ; tendrils forked, VUis 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. astivalis (summer grape).
Leaves covered with a dense, thick, felt-like tomentum when fully
grown, V. labrusca (Northern fox grape).

Vitis vinifera (Old-World Grape, Wine Grape, Raisin
Grape). — The Old-World grape is not as large a plant as
most American species. The leaves are thin, smooth, and
three- to seven-lobed; they may be smooth or woolly-hairy
when young; the lobes are rounded or pointed, and their
margins coarsely toothed. The oval, oblong, or globular
berries are in long and broad clusters.

The varieties of this species have a high sugar content.
On this account, they make better wine and raisins than
American varieties. American varieties are table grapes;
European varieties are wine and raisin grapes. The latter
are now grown in California, where the wine and raisin in-
dustries have developed to considerable importance. V.
vinifera is not resistant to the attacks of Phylloxera, a scale
attacking the leaves and roots. American varieties are
comparatively more resistant to these insects and on this
account are used as stocks upon which European varieties
are grafted.

^The key is adapted from "The Grapes of New York," by Hedrick.

500 BOTANY OF CROP PLANTS

Vitis vinifera is probably a native of western and southern
Asia.

Vitis rotundifolia (Southern Fox Grape) .^This is usually
a very vigorous, high-climbing grape, with hard wood and
smooth bark. The leaves are broadly heart-shaped, with
coarse, blunt teeth, hght green in color, smooth above and
below or sometimes slightly hairy on the veins below. The
large, spherical, black or greenish-yellow berries are in small
loose clusters. It grows wild from southern Delaware to
Missouri, Texas, and the Gulf States.

The varieties of this species are known as Muscadine
grapes. One of the chief varieties is the Scuppernong.

Vitis rupestris (Sand Grape). — This is a low shrub with small, broadly
beart-shaped, slightly lobed leaves with coarsely toothed margins. The
small, black or purple-black berries are in small clusters.

This species is southern in its distribution, reaching southern Pennsylvania
as its northernmost limit. It is very resistant to rot and mildew of the foliage.

Vitis riparia (River-bank Grape). — The river-bank grape is a rather
vigorous climbing plant with smooth and slender twigs. The leaves have
large stipules; the margin has sharp teeth that vary in size. The berries
are small, black, coated with a bloom, and occur in rather compact, but small
clusters.

This is the most widely distributed and the hardiest of American grapes.
It is common on stream banks in the United States east of the Rocky
Mountains.

Vitis aestivalis (Summer Grape). — This is a strong-growing species with
leaves that are short-stipulate, thick, three- to five-lobed, shallowly dentate,
dark green above and rusty pubescent beneath. The berries are astringent,
of average size, and usually in long clusters.

This species is native to southeastern United States. Its varieties are wine
grapes.

Vitis labrusca (Northern Fox Grape). — This is a stocky
plant with large, heart-shaped leaves which are either entire
or three-lobed, dark green above, and densely pubescent
below. The clusters of thick-skinned berries are medium
to large.

VITACE^ 501

By far the greatest number of cultivated grapes are varie-
ties of this species, or hybrids from it and other species,
chiefly Viiis vinifera, the Old-World grape.

Varieties of Table Grapes. — There are four very common
varieties of table grapes:

1. Catawba, hybrid of V. labrusca and V. vinifera.

2. Delaware, hybrid of V. labrusca and V. bourguiniana.

3. Niagara, hybrid of V. labrusca and V. vinifera.

4. Concord, variety of V. labrusca.

Color of Grapes.— Varieties of grapes may be grouped as
to color as follows:

1. Berries Purplish-black to Black. — America, August
Giant, Bacchus, Black Hamburg, Canada, Champion,
Concord, Ives, Mills, Muscat, Hamburg, Norton.

2. Berries Purplish-red. — Agawam, Brighton, Catawba,
Delaware, Diana, lona, 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

502 BOTANY OF CROP PLANTS

from a small, seedless grape. "English, "Corinth" or
"Zanta currants" are small dried grapes, grown chiefly in
the south of Greece, Table raisins are made from the most
select grapes, and usually dried in the sun, without pre-
liminary dipping. The lower grades of grapes that are made
into raisins for cooking purposes are nearly always dipped in
weak lye before thy are dried. California produces almost
all the raisins of the United States. According to the census
of 1910 the production of raisins and dried grapes in the
United States amounted to 169,245,100 pounds, of which
California furnished 169,210,675 pounds.

Wines. — There are two well-known sorts of wines: (i)
dry wines, and (2) sweet wines. Dry wines are those in
which the grape sugar has been converted into alcohol
through fermentation. Sweet wines are those in which the
grape sugar has not been converted into alcohol, but the
process of fermentation has been prevented by adding
alcohol. There are two groups of dry wines: (i) red wines
(clarets, Burgundies, etc.); and (2) white wines (Hocks,
Rieslings, etc.). Red wines are made from colored grapes,
the skins usually furnishing the coloring matter for the fer-
menting Juice. In the making of red wines, the skins and
pulp are crushed and placed in fermenting vats. The un-
fermented grape juice is termed "must." Fermentation is
brought about by the activity of yeast plants, and in this
process, the conversion of sugar to alcohol takes place.
After the completion of fermentation, the wine is drained
from the pomace (skins and other solid material of the grape)
and stored in various sorts of receptacles. A slow fermenta-
tion goes on in storage, and during this period, settlings
accumulate, which are finally removed, leaving the clear
wine product.

White wines are made from white grapes, or from those

VITACEiE 503

colored grapes with a colorless juice. The coloring matter
in the skin is not permitted to get into the juice, as the
skins are removed by pressing, and the juice allowed to
ferment alone.

The two chief sweet wines in this country are the ports
and 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

504 BOTANY OF CROP PLANTS

of tannin and grape oil. A brandy has been made by fer-
menting the sugary substance that sticks to the seeds, and
this material may also be made into a syrup.

References

Beach, S. A.: Notes on Self-pollination of the Grape. N. Y. State Agr.
Exp. Sta. Ann. Rept. 11: 597-606, 1892.
Self-fertility of the Grape. N. Y. State Agr. Exp. Sta. Bull. 157: 397-441,

1898.
Fertilizing Self-sterile Grapes. N. Y. State Agr. Exp. Sta. Bull. 169:
331-371, 1899.
Booth, N. O.: A Study of Grape Pollen. N. Y. Agr. Exp. Sta. Bull. 224:

291-302, 1902.
DoRSEY, M. J.: Variation Studies of the Venation Angles and Leaf Dimen-
sions in Vitis. Am. Breeders' Assn., 7: 227-250, 191 1.
Variation in the Floral Structure of Vitis. Bui. Torrey Bot. Club, 39: 37-

52, 1912.
Pollen Development in Vitis with Special Reference to Sterility, Minn.

Agr. Exp. Sta. Bull. 144: 1-60, 1914.
Pollen Sterility in Grapes. Jour. Hered., 6: 243-249, 1915.
Hedrick, V. P.: The Grapes of New York. 15th Ann. Rept. N. Y. Agr.

Exp. Sta., vol. 3, part 2: 1-564, 1908.
HusMANN, George C, and Dearing, Charles: The Muscadine Grapes.

U. S. Dept. Agr. Bur. Plant Ind. Bull. 273: 1-64, 1913.
MuNSON, T. V. : Investigation and Improvement of American Grapes. Texas

Agr. Exp. Sta. Bull. 56: 217-285, 1899.
Rabak, Frank: The Utilization of Waste Raisin Seeds. U. S. Dept. Agr.,

Bur. Plant Indus. Bull. 276: 1-36, 1913.
Reimer, F. C, and Detjen, L. R.: Self -sterility of the Scuppernong and
Other Muscadine Grapes. N. C. Agr. Exp. Sta. Bull. 209: 1-23, 1910.

CHAPTER XXXIII

MALVACE^ (MaUow FamUy)

Habit. — Members of the family are herbs, shrubs, or
trees. Tree species are tropical. The mallows are usually
rich in mucilage.

mvolucral bract

s^ \ \ca\\jlc
^pefal

D\sU\

wonadeliphou^

.ngement of parts
(After Cook, U. S. Dept. Agri.)

3\drx\er]6

Fig. 211. — Diagram showing arrangement of parts in the cotton flower.

Leaves. — The leaves are alternate, and mostly palmately
veined and palmately lobed. The stipules are small, narrow,
and deciduous.

505

5o6

BOTANY OP 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 (AlihcBa),
the involucre consists of six to nine bractlets united at the

^tapntnal
column

Fig. 212. — Upland cotton (Gossypium hirsutum). Median lengthwise
section of flower. X 2.

base; in Abutilon, there is none; in Hibiscus, it is of numerous
narrow bractlets; and in cotton (Gossypium), there are three
large heart-shaped bractlets (Fig. 211). The flowers are
regular (Fig. 212), perfect, often large, rarely dioecious or
polygamous. There are five sepals (rarely three or four),

MALVACE^ 507

more or less united, the lobes valvate or rarely imbricate.
There are five petals, slightly united at the base, convolute
in the bud, and often contorted. The stamens are character-
istic features of the family. They are numerous, and united
to form a long tube enclosing the styles; the staminal tube
is united with the bases of the petals (Fig. 212). There are
five more or less distinct projections at the top of the tube
of stamens; this seems to indicate that there are in reahty
but five stamens, united by their filaments, and branched
above into numerous stalks bearing pollen sacs. This is
further evidenced by the fact that each stalk bears a single
pollen sac, a structure equivalent to one-half of a typical
anther. The stamen tube may be anther-bearing at the
summit, as in Malva, Abutilon, etc., or anther-bearing below
the summit, as in Hibiscus and Gossypium. The ovary is
several-celled. Usually, there are as many styles as cells
of the ovary; the styles are united below, and distinct above,
and generally project beyond the stamen column.

Fruit and Seeds. — The fruit is a several-celled capsule
(rarely a berry). The seeds are kidney-shaped, globose or
obovoid, and have large cotyledons and either little or
abundant endosperm.

Geographical. — Members of the family are widely distributed in tropical
and temperate regions. There are about 40 genera and 800 species.

Economic Importance. — The mallow family possesses one
of our most valuable economic plants — cotton (Gossypium).
Cotton is the chief fiber plant of the world. It is grown
throughout tropical and subtropical regions. Another crop
plant is okra or gumbo {Hibiscus esculentus). Althcea
officinalis is the marsh mallow, the roots of which are used
principally for mucilage and for medicinal purposes. Orna-
mental representatives are hollyhock (Althcea rosea), mallow

5o8 BOTANY OF CROP PLANTS

(Malva spp.), poppy mallow (Callirhoe spp.), Abutilon
and Hibiscus. The Rose of Sharon is Hibiscus syriacus.

Key to Important Genera of Malvace^

Stamen column anther-bearing at the summit.
Carpels one-seeded.

Involucre of six to nine bractlets, AUhaa (marsh mallow and holly-
hock).
Involucre of one to three bractlets, or none.
Petals notched at the apex, Malva (mallow).
Petals erose at the apex, Callirhoe (poppy mallow).
Carpels two- to several-seeded, Abutilon.
Stamen column anther-bearing below the summit (Fig. 212).
Bractlets of involucre, numerous, Hibiscus.
Bractlets of involucre, three, Gassy pium (cotton).

' GOSSYPIUM (Cotton)

Habit of Plants, and Roots. — There are more than 40
species of Gossypium, all of which are perennial in their
native home. There are herbaceous, shrubby, and tree-
like species. In cultivation, the plants are annual or biennial,
and herbaceous.

There is a long, branching, and deeply penetrating tap
root. This extends to a depth of 2 feet or more in sandy soil.
There are four rows of lateral roots from four shallow grooves
that run lengthwise on the main root. The lateral roots are
only a few inches below the soil surface.

Stems. — The main stems are erect and branching. The
usual height of Upland cotton plants is 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 Hmbs may arise

MALVACE^

509

from either axillary or extra-axillary buds. Normal fruit-
ing branches arise only from extra-axillary buds. It fre-
quently happens that both a fruiting and a vegetative branch
arise at one node, that is, both the extra-axillary and true
axillary buds develop. Ordinarily, however, only one bud
at a node develops. The axillary buds usually develop into

Fig. 213. — Upland cotton (Gossypium hirsutum). A, mature boll opened out;
B, cross-section of young boll; C, single seed with fibers; D, young boll.

branches at only a few nodes on the lower part of the main
stem. The accompanying extra-laterals remain dormant.
On the other hand, the upper true axillary buds normally
fail to develop, while each of their accompanying extra-
laterals forms a fruiting branch. Hence, in most cultivated
cotton varieties, no fruiting branches occur on the lower part
of the main stem.

5IO BOTANY OF CROP PLANTS

In Upland varieties the fourth or fifth node is the first at
which fruiting branches are produced; in Egyptian cotton,
the first fruiting branches are produced from • the eighth
to the fourteenth nodes.

Vegetative and fruiting branches 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 in Egyptian cotton than in Upland cotton. The
internodes of vegetative branches are about equal in length.
Vegetative branches may form both fruiting and secondary
vegetative branches, but fruiting branches seldom bear
secondary fruiting branches or vegetative branches. Cottons
with short-jointed fruiting branches are more productive and
usually earlier than those with fewer and longer internodes.

Form of Plant. — The general form of the cotton plant is
determined to a large extent by the length and number of
vegetative branches, as well as by the angle they make with
the main axis. The plant may consist of a single stalk with
a number of fruiting branches but no vegetative branches.
An excessive development of lower vegetative branches
makes a bushy plant.

Branch Zones. — The cotton plant frequently has three
branch zones. This condition, described by McLachlan, is
pronounced in Egyptian cotton. The zone of vegetative
branches extends from the third to the tenth node; this is
followed by a "transition zone" or "zone of rudimentary
branches," of two or three nodes "at which the buds remain

MALVACE^ 511

dormant, or the branches are extremely short or abortive."
The "zone of fruiting branches follows from about the
thirteenth node to the tip of the plant."

Underground Stems. — The cotton plant may produce
underground stems. These arise from the same grooves from
which lateral roots come. At first, these subterranean shoots
are gall-like. Later, they attain various sizes.

Leaves. — The leaves have a regular spiral arrangement.
The most common phyllotaxy in the cotton plant is three-
eighths. This is the normal arrangement in all pure strains
of Upland and Sea Island species and other natives of tropical
America that are related. It is pointed out that with "the
advance of acclimatization, the leaf arrangements are varied
by frequent examples of one-third and two-fifths spirals"
. . . Egyptian-Upland hybrid plantsmay have a one-third,
two-fifths, or five-thirteenths arrangement. The phyllo-
taxy is one-third in Asiatic cottons. However, when Asiatic
species are crossed, the hybrid plants may show a two-fifths
or three-eighths arrangement. Leaf arrangement is similar
on main stem and vegetative branches, but on fruiting
branches the leaves are in two alternate rows; this latter
condition is brought about by a twisting of the joints, each
internode being twisted in the opposite direction from the
adjacent.

The leaves are petioled, stipulate, cordate as a rule, and
three- to seven-lobed, sometimes nine-lobed. Glands may
be present or absent on the leaves. When present, they
occur on the under side of the main ribs, about one-third of
the distance from the bases.

The leaves on fruiting branches are often irregular in outline
and may have one or two glands. The leaves on vegetative
branches and on the main stem are regular in outline, and have
nectaries on the midrib and occasionally on the principal

512 BOTANY 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,

MALVACE^ 513

scarcely lobed. The calyx lobes often vary in size. There
may be two large lobes, two small ones, and one intermediate
in size. Floral nectaries appear at the base of the calyx on
the inner side.

" Intracalicary Organs." — These sometimes occur in the
cotton flower. They are a series of small greenish organs
between the calyx and corolla. There are five of these
structures, but often some of them are so small as to be visible
only by use of the hand lens. They are attached to the
calyx, and alternate with its lobes. Cook and Meade regard
them as "supernumerary calyx lobes or as representing free
stipular elements of the calyx lobes."

Corolla. — This is hypogynous. There are five petals, often
united at the base, and attached to the lower part of the
stamen tube. They are usually yellow or red in color. In
G. harhadense the petals are yellow or sulphur-colored, with a
purple spot on the claw. The petals are convolute in the
bud.

Stamens. — These are monodelphous in cotton. There are
often as many as 80 or 90 stamens, all inserted on a tubular
staminal column, which encloses the pistil. The column is
dilated at the base and narrowed above. There are five
vertical ridges on the staminal column, each of which gives
rise to a number of filaments. The column is regarded as
being made up of the united filaments of the stamens. The
filaments are thread-like and exserted. The anthers are one-
celled, and each is dehiscent into two halves, by a semicircular
opening.

Ovary (Fig. 213). — This has three to five cells or "locks."
As a rule, the style is long, thus bringing the stigmas above
the stamens. In Upland varieties, however, the style is
usually shorter than the stamens. There are as many
stigmas as there are cells in the ovary.
33

514 BOTANY OF CROP PLANTS

Pollination, Fertilization, and Development of Fruit. —

Both cross- and self-fertilization may occur in cotton. Bees
may be necessary in those varieties in which the style is long
and brings the stigmas above the anthers. Floral nectaries,
at the base of the calyx on the inner side, are reached from
within the corolla by long-tongued bees and butterflies.
This is enabled by the failure of the petals to overlap at
the base, thus leaving gaps through which the insect may
protrude its tongue.

In Mississippi the period required for maturity of bolls is
from forty-four to forty-six days.

The seeds retain their attachment to the placenta until lint
begins to develop, when their connection is broken through
the absorption of the seed stalk, and the mechanical pressure
of growing lint. Hence, the seeds come to occupy a position
in the center of the cavity. Fiber begins to develop first at
the apex of the seed.

Fruit. — The cotton fruit (Fig. 213) is a leathery capsule
loculicidally dehiscent by three to five valves. The mature
capsule is called a "boll." It varies in shape: subglobose,
oval, or ovate-acuminate. The number of cells or "locks"
is three or four in Sea Island and Egyptian varieties, and four
or five in Upland sorts.

Seeds. — There are numerous seeds in each "boll." Seeds
vary in shape: subglobose, ovate, or subovate.

Fiber. — The cotton fiber or hair is a simple extension of an
epidermal cell of the seed coat. As a rule, there are two kinds
of hairs on the seed: (i) long hairs — lint or commercial
fiber "(staple)" and (2) short hairs or fuzz. The fuzz may
be white, green, or brown in color. Some varieties produce
no fuzz; hence when the seed is "ginned," it is left naked.
Fuzzy-seeded varieties usually possess an abundance of long
fibers. A high percentage of lint usually indicates small

MALVACE^ 515

seed. In some varieties, the lint may form 34 per cent, or
more of the seed.

Distribution of Seed Hairs. — ^Lint and fuzz are mixed to-
gether over the entire seed surface in Upland cottons. In
Egyptian sorts, fuzz is limited to the ends of the seeds, with
long fibers between thet\YO patches. The lint at the tip of
the seed in some Upland cottons is longer than that at the
base.

Fiber Differences. — The fibers of Upland cotton are i to 2
centimeters long, and abundant; those of Sea Island are 2.5
to 4 centimeters long, but the yield is not as great as in the
preceding species.

The following table is taken from Monie:

Average length of Average diameter
staple in inches of staple in inches

Sea Island 1.61 o. 000640

New Orleans 1.02 0.000775

Texas i . 00 o . 000763

Upland 0.93 0.000763

Egyptian 1.41 0.000655

Form and Structure of Fiber. -^Yoxxng 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

5l6 BOTANY OF CROP PLANTS

breadth. Immature fibers or unripe fibers may show no
evidence of internal structure, but are smooth, straight, and
flat. "Kempy" fibers or "dead cotton" are such that are
normal in structure a portion of their length, and have the
appearance of immature and overripe fibers for another
portion. The quality of fiber depends largely upon the
number and regularity of twists, and upon its length and
fineness. The mature cotton fiber is almost pure cellulose.

Cotton Fibers Distinguished from Other Common Textile Fibers. — There
are two chief ways of distinguishing textile fibers, by microscopical examina-
tion and by chemical reactions. The cotton fiber is a flat, ribbon-like band
twisted in a characteristic manner. The flax fiber is a straight, untwisted,
cylindrical fiber, with peculiar transverse markings at intervals along its
length. Hemp fibers resemble those of flax, but they may be distinguished
from the latter by the peculiar forked ends which are nearly always exhibited,
whereas flax fibers never show this character. All wool fibers possess char-
acteristic overlapping scales. The silk fiber is smooth, structureless, trans-
parent and quite regular in diameter.

There are many ways of distinguishing the fibers by observing their reac-
tions to various chemicals. The following short key will illustrate a few of
their characteristic reactions.
Dissolves in caustic potash.

An alkali solution of the fiber treated with lead acetate colors fiber

black. Wool.
The above treatment does not color the fiber. Silk.
Does not dissolve in caustic potash.

With iodine and sulphuric acid the fiber swells and becomes green,

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:

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. sturtii, davidsonii,
klotzschianum, robinsoni, darwinii, tomentosum, drynarioides, harknessii, and
stocksii. The bracteoles are free, extrafloral nectaries absent, the fruit small,
and the rather large seeds have a fuzz but no lint.

Section II. Fuzzy-seeded Cottons with United Bracteoles. — "One or perhaps
two members of this section have been recorded as met with in a wild condi-
tion, the others are undoubted cultivated plants derived very possibly from
four specific types — G. arboreum, G. nanking, G. obtusifolium, and G. herba-
ceum." Most of these are Asiatic and African cottons. The bracteoles are
united below, the claws of the petals are purple, and the seeds are covered
with both fuzz and lint. Watt is strongly of the opinion that G. arboreum var.
neglecta, was at an early date introduced into the United States, the form being
known as "Okra." Its cultivation was abandoned, however.

G. nanking is the "Chinese cotton" of commerce, also known as "Siam
cotton" or "Nankin cotton." It is "cultivated in China, Japan, the Malaya,
Siam, Burma, India, the northwest Himalaya, Persia, Central Asia, to the
Celebes; less abundantly in Madagascar, Arabia, and Africa."

G. obtusifolium is an oriental species that occurs both wild and cultivated
in India and Africa. Var. wightiana is the most valuable Indian cotton.

G. 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 1621, it was brought to the United States, and for a time cultivated, but
was finally replaced by the more desirable West Indian cottons. G. 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. muslelinum, punctatum,
hirsutum, palmerii, fruticulosum, schottii, lanceolatum, microcarpum, pertivi-
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. palmerii, fruticulosum and lanceolatum are Mexican
species. G. schottii is from Yucatan, and is known as the "split-leaved" cot-
ton. G. microcarpum, known as Ashmouni cotton and Red Peruvian cotton,
grows in Mexico, northern South America, Africa, and Malaya. It is culti-
vated. G. peruvianum is the Peruvian or Andes cotton. Watt regards many
of the Egyptian cottons as races or hybrids of this species. G. mexicanum

Si8

BOTANY OF 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. hirsutum." He con-
siders many of our Upland or short staple cottons as hybrids of G. mexicanum
and G. hirsutum, sometimes with the characters of the one predominating,
sometimes with those of thejother. 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 hirsutttm 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

MALVACE^

519

naked." To this section belong G. tailense, purpurasccns, vilijolimn, har-
badense, and brasiliense.

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. vitifoUum, the vine-leaved cotton, has fur-

FiG. 215. — Sea Island cotton (Gossypium barbadense). (After Wait.)

nished a number of valuable cultivated types in Egypt, Antilles, etc. It is
closdy related to G. barbadense. G. barbadense (Fig. 215) includes the Sea
Island cottons of America and Egypt. Watt believes that Sea Island cotton
is a modern development, not indigenous to Barbados or any of the West
Indian Islands, but probably from somewhere in South America. ^ He says

520 BOTANY OF CROP PLANTS

that "it is highly probable the modern stock is a hybrid." The Sea Island
cottons proper which have been grown with the greatest success on the islands
off the coast of Carolina and Georgia are referred to G. barbadense var.
maritima. G. brasiliense is indigenous to South America. It is cultivated
extensively and is known as " Chain, Kidney, Stone, Brazilian, Guiana, Esse-
quibo, Berbiche, Bahia, Pernambuco, and Coton-pierre cottons." This group
is no longer of great commercial importance.

Section V. Naked-seeded Cotton with 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

Wild Cottons. — Wild cottons all have a red-colored, hairy
coating on the testa. As is seen above, there may be fuzz
only, or both fuzz and lint, or lint alone. Cultivated cottons
have a long white lint, in both fuzzy-seeded and naked-seeded
forms. Sea Island cottons have the least fuzz of all culti-
vated forms. White lint may be regarded as brought about
by cultivation. The appearance of rust-colored fuzz or
lint may be regarded as a tendency to revert to the ancestral
type.

The reddish tint of wild cottons is due to an aggregation of
colored particles in the central core of the fiber.

American Cottons. — American authorities place the cot-
tons of the United States into two species: G. hirsutum,
American Upland cotton, and G. barbadense, Sea Island,
cotton. It has been noted above, however, that Watt claims
that our Upland cottons are hybrids between G. hirsutum
and G. mexicanum. Ninety-nine per cent, of the cotton
crop in the United States is Upland.

The most important distinction between these two species
is in staple length. The fibers of Upland cotton are from i
to 2 centimeters long, those of Sea Island 2.5 to 4 centimeters
long. The yield of the former is greater but the quality not
so fine. The flowersare white, turning red on the second day
of blooming in Upland cotton, but yellow with a purple-red

MALVACE^ 521

spot at the base of each petal in Sea Island cotton. The
latter is limited to a small area along the coast of South
CaroHna, Georgia, and Florida.

Tjrpes and Varieties. — Upland is the chief American cotton. It has been
divided by Duggar into a number of "groups" as follows:

1. Big Boll Group. — Plants vigorous and stocky; limbs strong, usually two
in number; fruiting branches strong, varying from short to long; bolls large,
45 to 68 of them yielding a pound of cotton; four to five locules; seeds large,
very fuzzy, white to brownish gray or greenish in color; lint 20 to 30 milli-
meters long. Examples: Russell, Truitt, Truimple, Texas Storm-proof, and
Jones Improved.

2. Long Staple Group. — Plants slender; limbs two or three, sometimes ab-
sent, slender; fruiting branches also slender; bolls small to medium, long,
slender, tapering to a point, three-, four-, or five-loculed; seeds medium to
large, sometimes partly naked, but usually densely covered 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, Defiance, 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; limbs one to three or
more; fruiting branches medium to short-jointed, but long in proportion to
plant height; bolls small, three-, four-, or five-locked; seeds small to medium,
fuzzy, greenish or brownish gray; lint short to medium, t,^ 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. .

8. Intermediate Group. — This group includes a number of varieties with

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, Tucker.

Environmental Relations. — Cotton is a tropical plant.
The upper latitudinal limit of cotton growing in this country
is about coextensive with the summer (June, July and Au-
gust) isotherm 77°F. The plant is extremely sensitive to low
temperatures, and even a light frost in the fall stops its
development. It seldom matures in less than i8o days.
The plant not only requires a high temperature, but also
one not subject to fluctuations, as such conditions cause
premature ripening. After the plant has attained its vege-
tative growth, the ripening of fruits and seeds is favored by
cooler nights than prevailed up to that period.

Light, frequent showers which permit of an abundance of
sunshine favor the development of the plant. Too much
rain is liable to stimulate an excessive development of vege-
tative growth at the expense of fruit formation.

Upland cottons are adapted to a variety of soils, while the
Sea Island varieties are best suited to soils with low water-
retaining capacity, and of medium fertility.

Picking and Ginning of Cotton.— Cotton is picked by
hand, and loaded into wagons. This labor is performed
almost exclusively by negroes. The seed cotton is removed
from the wagon by means of a suction fan, and carried over
a single gin or battery of gins. It passes into chutes over the
feeders, and is then fed evenly to the gin saws, where the lint
and seed are separated. The^seeds are carried by a screw
conveyor to the seed house or seed bin. The lint cotton is led
from the gin saws through a flue to the condenser. Here it is
cleaned, smoothed out into sheets or bats, wrapped and tied
into bales. The usual size of a cotton bale is 27 by 54 inches
and'the weight about 500 pounds. Sea Island cotton is ginned

MALVACE^ 523

in a type known as the roller gin, as the fiber is injured by the
saw gin type.

When seed cotton comes to the gin, it contains boll hulls
and trash. This is usually removed by passing the seed
cotton through a cleaner, before it reaches the gin saws.
The boll hulls are frequently used for fuel.

Bleaching of Cotton. — The object of this process is to
remove the waxy coating of the fiber, in order that it may
absorb the dyestuffs easily, and also remove all the impurities
adhering to the fiber. Cotton may be bleached in any stage
of its manufacture, in the loose state, as yarn, or as cloth.
The process of bleaching is the most thorough and is carried
further in the making of print cloth than in the preparation
of other grades of cloth, as the cloth must be absolutely white
and free of all impurities in order that the printing colors
can be applied properly, and the patterns appear distinct
and sharp. The cloth is first singed to remove loose fibers
and lint, and leave a clear even surface. It is then taken
through the boiling out process, in which the cloth is given
one or more 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 lime compounds and
undecomposed chlorine derivatives. Another thorough
washing then follows, after which the cloth is given a finish,
the nature of which depends upon the use to which it will
be put.

Uses of Cotton.— The lint is spun into thread or yarn, arid
woven into all sorts of fabrics. The finer threads are made
from Sea Island cotton, while ordinary threads and yarns
are from long staple upland cotton. The short lint or fuzz.

524 BOTANY OF CROP PLANTS

known as "linters," which is not removed in ginning, is
taken from the seeds and made into coarse twine, carpets,
and batting.

Cottonseed Hulls. — These are used in the manufacture of
paper and fiber board from which are made gear wheels,
trunks, etc. The hulls are also utihzed as fuel and fertilizer,
and as a cattle food.

Cottonseed Oil. — This is one of the most valuable products
of the cotton plant. The oil of the seed is in the embryo.
After the seed coats are removed, the embryos ("meats"),
are cooked for twenty to thirty minutes to melt the oil, and
to drive off some of the water. The oil is then extracted
under pressure. A ton of seed yields about 40 gallons of
crude oil. Various grades of cottonseed oil are secured by
different processes of refining and filtering.

Cottonseed oil is now produced in large quantities in this
country. The United States exported 35,304,000 gallons
of the oil in 1 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 ground cake
left after the oil is pressed from cotton seed. It is now used
extensively as a feed, although formerly it was considered
of little value. United States produces annually about
2,000,000 tons of cottonseed meal, valued at about $53,000,-
000. The death of animals sometimes associated with its
use is due to a toxic substance, gossypol. Cottonseed

MALVACEAE

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 alkah, thus oxidizing the

t3 J«

-Si !»

t-1

oj a.

o -o

u .
O 2^2

Y •? -o

gossypol and rendering it non-toxic. Cottonseed meal is
also highly prized as a fertilizer.
Guncotton.— This is a powerful explosive made by treating

526

BOTANY OF CROP PLANTS

cotton or some other form of cellulose with nitric acid or
sulphuric acid. 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 guncotton in ether and alcohol.

Fig. 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.)

Importance, and Production of Cotton. — Cotton is the
most important fiber plant in the world. The clothing of a
great majority of people is cotton. The largest of manufac-
turing enterprises are concerned with the production of cotton
goods. Cotton is the most important article of world trade.
The world's crop in 1910 is estimated at 22,433,269 bales, as
compared with 15,893,591 bales in 1900. In 1914, the United

MALVACE^ 527

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, 1915.

Production of Lint (Excluding Linteks) ik soo-pound Gross Weight
Bales, by States, iqis

State Bales

Texas 3,175,000

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 cylindricaljand usually rough-hairy. The
leaves are large, heart-shaped, three- to five-lobed, and with
very prominent veins; the lobes are coarsely toothed. The
solitary, showy flowers arise in the leaf axils; they are
subtended by numerous, narrow, involucral bracts; the
calyx is five-cleft; there are five large yellow petals; the
stamens form a column which is five-toothed at the apex, and
is anther-bearing along its entire length; the ovary has five
cells, each of which has several ovules; there are five style
branches, each tipped by a capitate stigma. Okra is regu-
larly cross-pollinated by insects, chiefly bumblebees. The
fruit is a pod with five longitudinal ribs; the seeds are large
and kidney-shaped.

528 BOTANY OF CROP PLANTS

Geographical. — The original home of okra is Africa. It is now introduced
into many civilized countries, and grown as a vegetable with particular suc-
cess in the warmer ones.

Types.— Beattie divides the varieties of okra into three
types: (i) Tall green, (2) dwarf green, and (3) lady finger.
Each of these is further divided into long-podded and short-
podded sorts. Plants of the "lady-finger" type are much
Hghter in color than those of the other two types. Tall
green okras are 4 to 8 feet high, dwarf green sorts about i}4,
to 2>}"2 feet high, and lady-finger varieties close to 3 feet high.

Uses. — Okra is used chiefly in soups. Not infrequently
the young seeds are cooked. When the pods are very young
and tender, they are cooked and served as a salad. A fiber
used in the manufacture of paper is sometimes made from
both stems and mature pods. In some countries the pods
are dried, and in this form kept for winter use.

References

Balls, W. L. : The Sexuality of Cotton. Yearbook Khediv. Agr. Soc. Cairo,

1905.
Beattie, W. R.: Okra: Its Culture and Uses. U. S. Dept. Agr. Farmers'

Bull. 232: 1-16, 1905.
Bowman, F. H.: Structure of the Cotton Fiber. Manchester, England, 1881.
Brooks, E.C.: The Story of Cotton. Chicago, New York, and London, 1911.
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, 191 1.
Cook, O. F., McLachlan, Argyle, and Meade, R. M.: A Study of Diversity

in Egyptian Cotton. U. S. Dept. Agr. Bur. Plant Ind. Bull. 156: 1-60,

1909-
DuGGAR, J. F.: Descriptions and Classification of Varieties of American

Upland Cotton. Ala. Agr. Exp. Sta. Bull. 140: 1-104, 1907.
Evans, W. H.: Botany of Cotton. U. S. Dept. Agr. Office of Expt. Stats.

Bull. 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.

MALVACE^ 529

Heizmann, H.: Die Baumwolle. Zurich und Leipsic, 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.

CHAPTER XXXIV
UMBELLIFER^ (Carrot Family)

Stems and Leaves. — All the common representatives of
the carrot family are herbs. A very few are shrubs or trees.
The stems are usually hollow. The leaves are alternate,
sometimes opposite at the base of the stem, and as a rule
pinnately or ternately compound. In a few genera (as
Bupleurum, Hydrocotyle and Oxypolis), they are simple. In
Sanicula, they are digitately parted or lobed. In the carrot,
fennel, and others, the leaves are decompound. The petioles
are frequently swollen and broadened at the base and partly
sheathe the stem. There are no stipules, or, if present, are
very small.

Inflorescence and Flowers. — The inflorescence is nearly
always an umbel, either simple or compound, but occasionally
a head (as in Eryngium). The umbel is so characteristic
of this group of plants as to suggest the name " UmbeUif erae "
(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 (Httle 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
S30

UMBELLIFER^

531

ovary; the limb of the tube is absent, or divided into five
inconspicuous teeth. The corolla consists of five separate
petals, attached to the base of the calyx tube; the tips of the
petals are usually turned in, and emarginate or two-lobed.
There are five stamens, curved inward in the young flower,
with fihform filaments and versatile anthers. The single,

^kamen

Fig. 218. — Parsnip (Pastinacasativa). A, median lengthwise section of
flower, X 12; B, face view of same, X 12; C, dorsal view of single mericarp, X
2H; D, floral diagram; E, schizocarp with mericarps separating at maturity,
X 2>^; 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, fiHform styles borne on a
swollen nectariferous style foot, the stylopodium (Fig. 218).
In some genera (as Apium, celery), the stylopodium is
inconspicuous or wanting. The umbellifers are usually
insect-pollinated. Protandry is common.

532 BOTANY OF CROP PLANTS

Fruit. — The umbelliferous /m^'/ (Fig. 218) is very charac-
teristic. It is termed a schizocarp, i.e., a dry fruit of two
carpels, these separating at maturity along the midline or
commissure into two one-seeded halves — the mericarps.
Each individual carpel or mericarp is indehiscent. The two
mericarps remain attached for a while after sphtting 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 bundles. In
some cases, there is one secondary rib in each of the four
furrows or grooves between the primary ones, thus making in
many instances nine ribs (five primary, four secondary) to
each half of the mature fruit. Within the grooves, as is
best seen by a cross-section of a mericarp (Fig. 218, F), are oil
tubes (vittae), running lengthwise of the fruit. These tubes
contain secretions of balsams, resins, and volatile oils, which
impart to the fruit its characteristic odor and taste. The
fruit may be bristly (as in carrot) or smooth (as in parsnip,
and many others). The bristles may cover the fruit (as in
Sanicula), or be confined to the ribs (as in carrot). Oil
tubes are sometimes obsolete or obscure (.as in Conium,
Hydrocoiyle, Washingtonia). If distinct, they are solitary
(as in parsnip) or several (as in Angelica, Cymopterus).
There are usually two or more oil tubes on the commissural
side, that is, on the side that is contiguous with the adjoining
mericarp.

The fruit is either flattened laterally (at right angles to the
commissure), or flattened dor sally (parallel to the commis-
sure), or in some instances not flattened at all (terete or
nearly so). The one seed in each carpel completely fills the

UMBELLIFER^ 533

whole cavity and is usually adnate to the pericarp; the inner
seed faces may be concave or flat. There is considerable
oily endosperm present in the seed. The small embryo is
imbedded in the endosperm near the hilum. The fruit is of
greater taxonomic importance than any other portion of the
plant. Usually, it is necessary to have the mature fruit
before an accurate determination can be made of a species in
hand. Keys to the genera and species are largely based upon
fruit characters.

Geographical. — The carrot family is one of north temperate regions, not
being well represented in the tropics. According to Britton and Brown, there
are close to 1,600 species in about 170 genera.

Key to Genera of Economic Importance

Fruit bristly, Dauciis (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, Ftenictdum (fennel).
Involucre present; leaves ternately compound, Canim (caraway).
Stylopodium flat or wanting, Apiiim (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 hypocotyl and prominent tap root, both of which
become fleshy, forming the so-called "carrot." Four longi-
tudinal rows of secondary roots are given off from the tap
root. The roots are much thinner and woodier in the wild
form of the carrot than in cultivated forms.

534

BOTANY OF CROP PLANTS

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 decompound (doubly
compound). 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.

UMBELLIFER^

535

In the outer flowers, the petals are often two-lobed. The
stylopodium is depressed or wanting, and has two curved
stigmas.

Fruit and Seed. — The fruit (Fig. 219) is oblong and dor-
sally flattened. The five primary ridges of each carpel bear
long hairs, and each of the four secondary ridges bears
about ten long spines, at the ends of which are three or four
hooked hairs. The oil tubes (vittae) are soUtary in the in-
tervals, that is, under the secondary ribs, and two are on the
commissural side of each mericarp. The seed is flattened
dorsally, and the face plane or shghtly curved.

Geographical. — The wild form of Daucns 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.

Fig. 220. — Types of carrots (Daucus carota). A, Garden Ball; B, Early
Scarlet; C, Oxheart; D. Chantenay; E, True Danvers; F, Saint Vallery; G,
Long Orange.

Varieties. — There are numerous varieties of carrots vary-
ing as to size, [shape, color, and quahty. As to shape of

536 BOTANY OF CROP PLANTS

the vegetable, varieties may be divided into two groups
(Fig. 220).

1. Roots distinctly pointed, tapering (Long Orange, Saint
Vallery).

2. Roots blunt at the tip, not pointed (Early Scarlet
Horn, Ox-heart, Chantenay, Stump-rooted Half Long Red).

The roots may be white (Large White, White Vosges,
White Belgian), red (Carentan), orange or orange red (Early
French Forcing Oxheart, Long Orange), or purple-violet
(some Egyptian and Spanish varieties).

Uses. — Medium-size carrots, particularly those with yellow
or orange flesh, are used as a table vegetable and for the
seasoning of soups and stews. The larger, coarser varieties,
such as Large White, Large Yellow Belgian, Danvers and
White Vosges, are grown for feeding stock during the winter
season. The yellow coloring matter, carotin, is sometimes
extracted from the roots and used for coloring butter.

PASTINACA SATIVA (Parsnip)

Habit, Roots, and Stems. — The parsnip is of either
annual or biennial duration. When grown from seed, a
fleshy hypocotyl and tap root are first formed; these consti-
tute the "parsnip" vegetable. In the wild form, the root
and hypocotyl are thin, tough, and woody. During the
second season, a branching stem is sent up to a height of from
2 to 3 feet. The tall, erect stems are grooved, smooth or
somewhat downy pubescent, and become hollow.

Leaves. — The lower and basal leaves are petioled, pinnately
compound, the thin segments ovate or oval, lobed, incised
or dentate. The upper leaves are sessile, much smaller than
the lower, and not so deeply lobed. The terminal leaflet of
each leaf is usually three-lobed.

UMBELLIFER/E 537

Inflorescence and Flowers.- The tlowers (l""ig. 221) arc
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 [)arsnip, thus (lilU'rin.i^ markedly

itiva).

from tin" carrot. The llowers are >i'llo\v. Tin- calyx teeth
are very small or absent, the petals incurved and small, the
stvloi)odium depressed, and the ovary inferior.

Fruit and Seed.- The fruit (Fig. 218) is l)roadly oval and
much llattened dorsally. The dorsal and two intermediate

538

BOTANY OF CROP PLANTS

priniar}- ril)sarL' Ihrcad-likc, while the lateral ribs are expanded
into broad. Hat wings, with those of the two mcricarps con-
tiguous. 'I'he oil tubes are solitary in the intervals; there
are iour on the dorsal side and two to four on the commissural
side. The olive-green seeds are llattened dorsally. The
seeds are very short-lived.

Geographical. — The wild parsnip, Paslinaca saliva, from which our ciilti-
valcd variolics arc derived, is a native of Europe. This wild form has l)c-
comc naturalized in many sections of Xortli America, occurring as a weed
along roadsides and in waste places.

Varieties.- — There are comparatively few parsnip \arieties.
rrobabl\' the most popular sorts are the Guernsey and Hollow
Crown. Tn both of these, the crown is concave.

Fi.;.

■Celery (Apium graveolens). A, schizocarp, external, X 15; B.
diagrammatic cross-section of scliizocarp, X 20.

APIUM (Celery and Parsley)

Generic Description.— Members of this genus are annual
or perennial herbs with pinnately dixided leaves. The white
or gveenish flowers are in compound umbels. The involucre
and involucels ma\' be present or wanting. The cal}x teeth

UMBELLIFER^ 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, smooth or covered with protuberances.
The mericarps have pronounced corky ribs; the oil tubes are
solitary in the intervals, with two on the commissural side.

Geographical. — There are about i8 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 leplophyllimi. These three species are distinguished in the
following key.

Key to Principal Spfxiks of Apium

Flowers greenish-yellow, Apimn petroselimim (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 foKage and are more capable of renewing the
tops after being cut back than plants from small seed.

Varieties. — As to leaf characters, there are two types of
parsley :

540 BOTANY 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 stunted
or set back in their development, seed stalks may be sent
up the first season. Of course, in celery growing, the
" seeders'' are undesirable and every effort is made to pre-
vent their appearance. Normally, however, seed stalks are
sent up from the short rootstock the second season. This
stem is erect, glabrous, and i to 3 feet high. The leaves are
pinnately compound with three to five oval, coarsely toothed
or incised leaf segments. The small white flowers are in
umbels. Involucre and involucels are small or wanting.
The fruit is oval, flattened laterally, and has corky ribs.
The oil tubes are sohtary in the intervals and two in number
on the commissural side.

Geographical. — Apium graveolens, the wild form giving rise to our cultivated
celery and celeriac, is a native of Europe. In eastern United States, it has
escaped from cultivation, and it is said that in the salt marshes of California
it has become naturalized.

Types and Varieties. — There are two types into which the
cultivated celery has been modified by breeding and selec-
tion: (i) common celery, with enlarged, tender, edible leaf
stalks, and (2) celeriac, "German celery" or turnip-rooted
celery {A. graveolens var. rapaceum), with a fleshy, turnip-

UMBELLIFER.E 541

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-blanching varieties — quick-growing, very tender, easily-
blanching sorts, especially adapted for fall and early winter
use (White Plume, Golden Self-blanching). Blanching (see
page 250) is secured by keeping the leaf stalks away from the

Fig. 223. — Celeriac (Apium graveolens). (After Vilmorin.)

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 hght.

(2) Green or winter varieties-r-not as quick-growing or
easily blanched as those of the preceding type and, further-

542 BOTANY OF CROP PLANTS

more, with better keeping qualities when stored for the winter
(Giant Pascal, Boston Market, Winter Queen, Giant White
Solid).

All cultivated varieties of celery require cool weather and
plenty of moisture for their best development; they are
intolerant of excessive heat. Celery culture is carried on
with the greatest success on reclaimed muck soils in regions
with a cool climate.

Uses. — Celery is grown principally for the thick, fleshy
leaf stalks. The leaves are also used for garnishing and
seasoning, and the. seeds are used for flavoring salads and
soups. The fleshy root of celeriac is used as a flavoring or
is stewed separately.

References

Coulter, J. M., and Rose, J. N.: Monograph of the North American Um-
belliferae. Contr. U. S. Nat. Herb., 7, No. i: 1-256, 1900.

CHAPTER XXXV
VACCmiACEJE (Huckleberry Family)

This is a widely distributed family occurring in tropical,
temperate, and arctic regions. It is closely related to the
heath family {Ericacece) which possesses such well-known
plants as kinnikinic {Ardostaphylos uva-ursi), the creeping
wintergreen {Gaultheria) , American Laurel (Kalmia), Labra-
dor tea {Ledum), Azalea, Rhododendron, and trailing arbutus
{Epigaa 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 sinall tree. Some South
American species are epiphytic.

Leaves. — The leaves are simple, alternate, often thick
and leathery and sometimes evergreen, and without stipules.

Inflorescence and Flowers.— The flowers are solitary in
the leaf axils (as in Chiogenes hispidula, the creeping snow-
543

544

BOTANY OF CROP PLANTS

.^^

berry, or Vaccinium membranaceum, the thin-leaved bil-
berry), or in racemes (as in Vaccinium virgatum, southern
, black huckleberry, or Vaccinium oxycoccus,

the European cranberry). The flower
pedicels are usually bracted. The small
flowers are perfect, sympetalous, and usu-
ally actinomorphic (Fig. 224). The calyx
(Fig. 225) forms a tube, grown fast to the
ovary, the limb (free portion) four- to
five-lobed or four- to five-cleft, and either
persistent or deciduous. The sympetalous
corolla is divided into four or five lobes
or very rarely into nearly separate petals, as in the cran-
berries. The corolla may be either globe-shaped, bell-
shaped, urn-shaped, or tubular. There are twice as many

Fig. 224. — Floral
diagram of Vaccin-
ium.

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

VACCINIACE^ 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 Gaylussacia).
The seeds are small, compressed, and have a bony seed coat,
and a small embryo imbedded in a fleshy endosperm.

VACcmroM

The representatives are shrubs or small trees. The leaves
are lealhexy. 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 falHng 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 oiT,

546 BOTANY OF CROP PLANTS

This fact serves to emphasize the need, in the propagation of
blueberries by cuttings, of making the plantation from
cuttings of a number of different bushes.

Fruit. — The fruit is a many-seeded berry. It matures
about two months after flowering. The berries are most
commonly blue-black in color, although albino forms are
known to occur. The calyx is permanently attached to the
fruit. Berries may remain on the bushes a month or more
after they have reached maturity without losing their flavor
or firmness.

Geographical. — The genus is widely distributed in the northern hemisphere,
mostly in North America and the Himalayas. It includes about 125 species,
about 27 or more of which are native to North America.

Key to Chief Fruit-bearing Species of Vaccinium

Fruit red in color.
Stamens included, V. vitis-idcea (cowberry, mountain cranberry, foxberry).
Stamens exserted.
Leaves ovate, acute at the apex; stems slender, creeping; berries

globular, V. oxyccccus (small cranberry).
Leaves oval or oblong, obtuse or retuse at the apex; stems stout,
creeping, with^ ascending branches; berries egg-shaped or oblong, V
macrocaipon (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, F. ccepitosum (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, V. angusiifolium (low blueberry).
Fruit without bloom, V. nigrum (low black blueberry).
Leaf surfaces hairy, V. canadense (Canada blueberry).

VACCINIACE^ 547

Plants tall, 3 to 12 feet, and spreading.

Flowers solitary in leal axils, I', ovalifoliiim (tall or oval-leaved bilberry).
Flowers in groups in leaf axils.

Fruit blue, V . rorymbosum (high bush IjJuebcrry, swamp huckleberry).
l''ruit black, V. alroco'ccum (black blueberry).

GAYLUSSACIA (Huckleberry, Tangleberry, Dangleberry)

Description.- ^Members of this genus are shrubs with alter-
nate and entire or finely toothed leaves. The inflorescence is
a raceme. The small white or p'mk flowers are on two-brac-
teolate pedicels. The calyx tube is short, iive-lobcd or
live-toothed, and persistent. The stamens are 10 in number,
and their anthers open by terminal pores. The fruit is
described as a berry-like drupe, or lo-celled drupe with 10
seed-like nutlets. The ''seeds" are each covered with
endocarf).

Geographical. — The genus is distributed throughout North and South
.'\merica. It possesses about 40 species. There are five species of Gaylussacia
growing in North America.

Kiev ru North American Species of Gaylussacia

Leaves evergreen, tinely toothed, G. bracltyceni (box-huckleberry).
Leaves deciduous, entire.

Fruit with a bloom, G. frondosa (blue huckleberry, tangleberry, dangle-
berry).
Fruit without a bloom.
Leaves 2 to 4 inches long, G. ursiiut (Carolina JuickKberry).
Leaves i to 2 inches long.

Bracts small, deciduous, G. rcsi)iosa l^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 stilT 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 Kentuck}' and Manitoba.

548

BOTANY OF CROP PLANTS

CRANBERRIES
Some botanists place the cranberries in the genus Oxycor-
cus, 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

y (Vaccinivim inacrocariH^n).

cranberries grown in America: American cranberry (K(/f-
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

VACCINIACEiE 549

leaves, whitened beneath, and with rolled margins. The
flowers are on short upright one-year-old shoots; they
occur in very short clusters; the corolla is hght pink. The
berry is red, ovoid, oblong, or almost globular. At the
summit of the fruit, are four persistent, short calyx lobes,
bent inward.

This species is found wild in boggy land in the northern
part of the United States, adjacent Canada, south along the
eastern coast to Virginia and North Carolina. It is also
found in South America. It is the cranberry that is culti-
vated to a large extent in the cranberry centers in this coun-
try— Cape Cod, New Jersey, Wisconsin, Michigan and Min-
nesota. The cultivation of cranberries in the United States is
practically confined to cool, moist boggy regions. Cran-
berries are grown in natural or artificial bogs, which are capa-
ble of being drained or flooded at will.

Types. — Corbett divides American cranberries into four
groups, based upon fruit shape.

1. Bell. — These are the most popular and include such
varieties as Early Black and Centennial.

2. Bugle. — Mathews, Howe, Centerville, Dennis.

3. Olive. — McFarlin's, Howes, Jumbo.

4. Cherry or Spherical Cranberries. — Early Red, Arpin,
Makepeace.

Vaccinium oxycoccus (Small Cranberry). — This is the
cranberry of the Old World. It is a slender, creeping plant
with thin stems, 4 inches to i foot long, and with ovate, acute
or acuminate leaves, dark green above, whitish beneath.
The flowers are very similar to those in the preceding species.
The berry is red, globular, four-celled, and often spotted when
young; it is smaller than that of the American cranberry,
although considered by some of superior quality.

The small cranberry is a native of alpine and subarctic

55° BOTANY OF CROP PLANTS

regions of Asia, Europe, and America. It is not cultivated
in America to any great extent.

Vaccinium vitis-idaea (Mountain Cranberry, Windberry,
Wolberry, Cowberry, Foxberry).^This is a low evergreen
shrub with creeping stems and thick, leathery leaves. The
flowers are in short, terminal, one-sided clusters. The
berries are dark red.

This plant grows wild from Massachusetts to Labrador,
west to British Columbia and Alaska. Although not cul-
tivated, the natives, particularly of Nova Scotia, gather
large quantities of this wild cranberry and ship them to
eastern markets.

HUCKLEBERRIES AND BLUEBERRIES

Both of the above names are applied to the fruit of species
of Vaccinium and Gaylussacia. However, it is uncommon to
see the name blueberry given to the fruit of Gaylussacia
spp. These bear lo seeds in each fruit, and although not as
numerous as in the berry of Vaccinium, are more trouble-
some. There are two general types of blueberries: high-
bush blueberries (F. corymbosum, and V. atrococcum),
and low-bush blueberries {V. canadense, V. angustifolium,
V. nigrum, and V. vacillans).

The common black huckleberry on the market is Gaylus-
sacia resinosa. . Vaccinium angustifolium is a rather common
low-bush blueberry, while V. corymbosum is the species most
desirable for cultivation.

References

CoviLLE, Frederick V.: Experiments in Blueberry Culture. U. S. Dept.

Agr. Bur. Plant Ind. Bull. 193: i-ioo, 1910.
Davis, W.T.: High-bush Blueberries. Proc. Staten Island Assn. Arts and

Sci., 2: 63-64, 1909.

CHAriKR WW 1
OLEACEiE (Olive Family)

Family Description.— This is a family of trees t)r shrubs.
Tlic h'dvcs are t)j)jK)site, cxstipulate, and simple or pinnatcly
comjiound. 'J'he iiiJJorcscencc is a panicle, raceme. CNine or
fascicle. The floivcrs are repjular, and polygamous or
dioecious; the small calyx is four-lobed, sometimes entirely
absent; the reguhir corolla is four-parted, or of four distinct
petals, or absent. 'J'herc are two stamens, attached to Ihe
corolla or to the receptacle. The single pislil 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 fruil is cither a capsule, samara, berry,
or (]ru})e.

Geographical, and Economic Importance.- 'J^iere are
about 2 1 genera and 500 species distributed widely in tem-
perate and tropical regions. The most im])ortant repre-
sentative is the olive {Olca curopa^a). Other well-known
members of the family are the lilacs {Syringa), privet (Ligus-
Irum), Jessamine (Jasminnm) and ash {Fraxinus).

OLEA EUROP(EA (OUve)
Description — 'J'he common olive is a small tree 20 to 25
feet higli. 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-
j)osite]}' on the stem. The floivcrs occur in axilhiry 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. 'Yhc fruit is a pur[)lish drupe.
551

552 BOTANY OF CROP PLANTS

'Jlu- olive is probably a native of the Mediterranean re<,non.
Its cultivation in this country is conhned almost entirely to

Fic. 227. — Olive (Olca eun.puja). Branch and fruit. (./•><;;« ((////. Agr.
Exp. Sl,t.)

the warm, dry portions of California. 'Yhc olive requires a
mean annual temperature of 57°F., and it is claimed that at
no time should the temperature go below t4°F.

OLEACE^ 553

Seed Germination. — If olive seeds do not receive some
treatment before planting, they will not germinate for a
year or more. This delay in germination is due to the thick,
stony covering, and to the oil present which inhibits water
penetration. The delay in germination has been overcome,
in part, by various means, such as soaking in warm water,
soaking in alkaline or acid solutions, cracking the stones, and
clipping the apex of the seed. The last method appears to
be the best.

Propagation. — The olive is very easily reproduced vege-
tatively; in fact, cuttings of any kind will grow. For propa-
gative purposes use may be made of green cuttings with the
leaves on, of chips from old trunks, of young or old limbs,
and even of knaurs. Knaurs are knots or excrescences formed
upon the trunks of old trees. When limbs 2 or 3 inches in
diameter are used, they are cut into lengths of i or 2 feet,
each spHt lengthwise, and planted horizontally with the
bark up. Sprouts readily arise from the section of trunk,
and such sprouts may be allowed to continue their growth
where they are, or be made into green cuttings.

Uses. — Olives are eaten either in the green or ripe state.
They are usually "pickled," and left whole, or "stuffed."
Olive oil is an important commercial product. The best
quaHty of olive 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 hydrauKc 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.

CHAPTER XXXVII
CONVOLVULACE^ (Morning Glory FamUy)

corolla
tube

-^'■slarmn

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), used as food by the
Indians, moon-flower {Ipomoda
hona-nox) , morning glory
{Ipomcea purpurea), cypress vine
{Quamoclit quamoclit) and the
bindweeds {Convolvulus spp.).

Habit. — Most of the repre-
sentatives of this family are
twining or trailing herbs; some
tropical species are shrubs or
trees, often with a milky juice.
Leaves. — The leaves are alter-
nate, exstipulate, entire, den-
tate, lobed, or dissected.
Inflorescence and Flowers. — The flowers are in an axil-
lary cyme, or sometimes soHtary. They are regular, perfect
and sympetalous (Fig. 228). The calyx is attached below
the ovary, five-parted or five-divided, usually persistent, aiid
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

-ovari)
cohx

Fig. 228. — Flower of sweet
potato (Ipomoea batatas), length-
wise section. (After Sargent-)

CONVOLVULACE^ 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 unequal. The anthers are two-celled, and
longitudinally dehiscent. The ovary is superior and usually
has two cells (rarely three cells), each of which bears two
ovules. In some instances, the ovary is falsely divided into
four to six cells, each with a single ovule.
Fruit.^ — The fruit is a capsule; its seeds are endospermous.

Key to Important Genera

Stigmas capitate (knob-like).

Stamens and style exserted, Quamoclit.

Stamens and style included, Ipomosa.
Stigmas two, filiform or oblong, Convolvulus.

IPOMCEA 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, solitary or cymose. The

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, Hght 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 flesh is watery, rich
in sugar, soft and gelatinous when cooked. They are the
sorts most in demand in the South. Common southern

CONVOLVULACEiE

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

SSS BOTANY OF CROP PLANTS

side near the apex (Fig. 230, B) (Delaware, Early Golden, Yellow Jersey,
Red Bermuda).

3. Leaves lobed (Fig. 230, C) (Barbadoes, Sugar, Yellow Yam, Vineless
Yam).

Sweet potato varieties may have skin color that is white, straw, red, or
purple.

1. Skin white (Vineless Yam, Early Golden, General Grant).

2. Skin straw (Orange, Delaware, New Jersey).

3. Skin red (Pumpkin, Red Bermuda).

4. Skin purple (Black Spanish, Brazilian).

Uses.' — Sweet potatoes are used chiefly as a human food.
Some of the coarser varieties are grown for hog pasture. The
vines have some value as a stock food. Flour, starch, glu-
cose, and alcohol are minor products of the root. Small-
sized sweet potatoes, known as "seconds," are canned.
Kiln-dried sweet potatoes produce a product very similar to
corn meal in its chemical composition.

References

Groth, B. H. a.: The sweet potato. Contrib. Bot. Lab. Univ. of Pa., 4-
1-104, 1911.

CHAPTER XXXVIII
SOLANACE^ (Potato Family)

The potato family is a large one, chiefly tropical; it has
about 1, 600 species in 70 genera. A number of these are
important medicinal and food plants. Here are included
such economic forms as Red or Cayenne pepper, tobacco,
common Irish potato, eggplant, tomatoes, belladonna
{Atropa belladonna) which furnishes the atropin of commerce,
thorn apple {Datura), petunia, etc.

Habit of Plants. — Representatives of the family are either
herbs (potato, tobacco, tomato), shrubs (Lycium spp.), vines
(Solanum dulcamara, bittersweet), or trees in some tropical
species of Datura.

Leaves — These are alternate, rarely opposite, without
stipules, and entire, toothed, lobed or dissected.

Inflorescence and Flowers. — The inflorescence is mostly
cymose, sometimes imperfectly racemose, umbellate, or
paniculate. The flowers (Fig. 232) are regular, or nearly so,
perfect, and vary in color. The calyx is inferior, and usually
with five united lobes. The corolla is sympetalous, mostly
fiveobed. The corolla varies considerably in shape: rotate
(tomato), bell-shaped {Phy sails), funnel-form {Lycium vul-
gare), salver-form or tubular (Petunia spp.) There are as
many stamens as corolla lobes, alternate with them, and
inserted on the tube; in most genera, the stamens are all
equal and bear perfect anthers, but in Petunia, for example,
there are four perfect stamens, the fifth being very much
reduced or entirely absent; the anthers are two-celled, dehis-
559

560 BOTANY OF CROP PLANTS

cent at the apex or along the sides. The single ovary is
usually two-celled (rarely three- to five-celled, as in Ly-
copersicon spp.), the numerous ovules being on axile pla-
centas; the style is slender, simple, and the stigma terminal.
Fruit. — The fruit is either a berry (potato, tomato), or a
capsule (tobacco, petunia). In both cases, it bears numer-
ous seeds, which have a fleshy endosperm.

Key to Important Genera

Fruit a berry (Fig, 233).
Anthers opening by a terminal pore or slit (Fig. 232), Solanum (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,

Nicoliana (tobacco).
Flowers solitary; stamens very unequal, Petunia (petunia).

SOLANUM

Habit. — The Solanums are either erect herbs (as S. nigrum,
the black nightshade, and the common potato, etc.), or
climbing herbs (5. dulcamara, bittersweet). In most species,
the stems and leaves bear a stellate (star-shaped) pubescence.

Leaves. — The leaves are alternate, exstipulate, and lobed
orfpinnately dissected.

Inflorescence, and Flowers. — The inflorescence is cymose
(bittersweet), umbellate (black nightshade), racemose {S.
carolinense, horse nettle), or rarely paniculate. The flowers
(Fig. 232) are perfect and regular; in color, they are white
(5. tuberosum varieties and S. nigrum), blue (S. ceagni-
folium, silver-leaved nightshade, and S. tuberosum varieties),

SOLANACE^ 561

yellow (S. rostratum, sand bur), or purple {S. 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 Hmb 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 sht,
and sometimes longitudinally. The ovary is superior, usu-
ally two-celled; its style is slender and simple, and the
stigma terminal.

Fruit. — The fruit is a many-seeded berry; the calyx is
persistent at the base, and in some species {S. rostratum)
encloses the berry.

Geographical. — There are about 900 species of Solatium, 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. Irijlorum

(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. caroHnense

(horse-nettle).
Flowers purplish} fruit large, 5. melongena (egg plant).
36

5^2 BOTANY OF CROP PLANTS

Berry enclosed by calyx, S. rostratum (sand bur, buffalo bur).
Tuber-bearing. *

*NoTE. — Berthault in his monograph on the tuber-bearing Solanums, has a
key to 37 species. A portion of this key is here included (modified) to show
the relation of common potato to some wild tuber-bearing species.
Corolla rotate.
Points of sepals long and tapering.
Leaves oval, S. tuberostim (common potato).
Leaves elongated, S. immile.
Points of sepals long, not tapering much; leaves oval, 5. chiloense.
Points of sepals short.

Anthers straight, smooth, somewhat elongated, S. utile.
Anthers swollen, roughened, 5. maglia.
Corolla star-shaped, 5. janiesii, S. commersonii, etc.

SOLANUM TUBEROSUM (Potato)

This species includes all the varieties that are of value for
food. They are usually called Irish or common potato, but
also white, English, and round potato. •

Habit. — The potato is a branched, more or less spreading
herb, growing to a height of 2 to 5 feet or more. It has
annual aerial stems, but is practically perennial by means of
its tubers or underground stems.

Roots. — Upon the whole, the development of the root
system is less pronounced than in most other crops. The
roots are fibrous and fine. They penetrate the soil to a
depth of 2 to 4 feet and frequently extend horizontally 2
feet or more from the plant.

Stems. — Potato stems are of two general kinds as to
medium in which they grow: Underground and aerial. The
underground stems (Fig. 12) are slender rhizomes, or are
swollen to form tubers (''potatoes"). The aerial stems are
the ordinary foliage-bearing stems. The discussion of
rhizomes and tubers is given on pages 29 and 31.

Stem (aerial) .—The aerial or foHage stem of the potato
is herbaceous and generally erect when young, but usually

SOLANACEyE

563

becomes spreading later. "It is smooth and generally solid.
It has no ribs at lust, but as it develops, it becomes more or
less quadrangular.

Leaves. — Potato leaves are compound jiinnate, with more

,U."Fl'>w

luim luhorosuni)

or less petioled leallets. The petiole bears a number of
supplemenLar>- leallets which vary in number and importance
with the age of the i)laiU. 'i'he rachis is decurrent (Fig. 12)
on the stem. The leallets are oval, acuminate, and the base
heart-shape or oblique in shape. The leaves as well as the
stems are characterized by a narcotic smell. At the begin-

564

BOTANY OF CROP PLAXTS

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 b\-
two lateral leaflets, and these by others, so that the leaf soon
becomes distinctly pinna titid.

Considerable diiTerences have been found to exist in the
appearance of the leaves of the ditTerent agricultural varieties.

Flower (Fig. 232). — The corolla is tubular, with fixe lobes.

^-terminal pore
^anther '

Fig. 232. — Potato (Solanum tuberosum). .1.
lengthwise section; C, flora

Ijcrry; />
<li;i^;r;un.

It is white, yellow, purple, or blue in color and i to i} 2 inches
m diameter. There is a single whorl of five stamens which al-
ternate with the corolla lobes, and are attached to thi- tube.
The stamens are straight, and bear erect, yellow anthers which
are longer than the filaments and o[)en onl}- 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 [slants do not always

SOLANACE^ 565

produce fertile flowers. Hence while the presence of round
pollen grains seems to be necessary to the production of fruit,
their presence by no means assures that the ovary will be
formed or fruit produced. The ovary consists of two carpels
with numerous ovules in each locule.

Opening of Flower and Pollination. — The anthers are
mature at the same time that the stigmas are receptive. The
flowers have been found to open between 5 and 6 o'clock
a.m. The pollen is usually shed on the second day of bloom-
ing, and at this time, the pistil is most receptive. The an-
thers open at the top by a pore and, in some cases, spHt for a
short distance. The pollen is carried by the wind. The
flowers produce no nectar and are not visited by insects to
any extent, although several species of insects have been re-
ported as visiting the flowers. East concludes from obser-
vations of his own (and of others) that self-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 Ufe and, furthermore, he found that many
of the heaviest yielding varieties bloomed as freely as those
of less value.

In many varieties, the flowers do not open. In the Pearl
variety, Fitch finds that tuber productiveness "is universally

566 BOTANY OF CROP PLANTS

proportionate to the sexual development of the plant; that
the most degenerate tuber is produced on the plant which
carries fully developed flowers and virile pollen; while those
plants on which only female portions of the flowers appear to
be fully developed, produce tubers intermediate in form and
yield, and that the best tubers and the largest yield are pro-
duced by the type of plant whose flower buds do not even
swell." Furthermore, these buds do not show any other
color than green and they soon wither and break off.

Fruit. — The fruit (Fig. 233) is a globular or short oval
berry with two locules containing numerous seeds attached
to the thick axil placenta and embedded in a green acrid
pulp. The fruit is called by various names, such as "potato
ball," "potato apple," or "apple," but is commonly referred
to as the " seed ball." In color the seed balls are brown,
purplish green, or green tinged with violet. Single fruits may
contain from a few to as high as 200 or 300 seeds, but some-
times no 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 a cluster, and lateral, sectional and
basal views. (After Stuart, U. S. Dept. of Agri.)

S68

BOTANY OF CROP PLANTS

ground 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 unbranrhed 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
finallx' 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-
vel()[)e(l at the tips of slender
stolons coming from the axils
of the cotyledon leaxes. Roots soon arise from the stolons.
Secondary sLtjlons appear in the axilsof the first foliage leaves.
Tubers from Seedlings. — Tubers produced on seedlings
are usually small the first \ear. However, Fra/ier rejjorts
a tuber weighing over 7 ounces thai was formed the first
year, and says thai the Kurbank [)olal() was full-sized the
first year from seed. U is rei)orted from Svalof (Sweden)
that tubers usually attain normal size and type after about
the third year from seed.
Tuberization. — It has been noted prexiously that tubers,

tuber

Fig. 234. — Young potato plant grown
from seed. (After Pcnival.)

SOLANACE^ 569

developed on a plant grown fron-i 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 6'.
commersonii, it is reported as sometimes reaching a length
of 10 feet. The tubers or swollen stems bear a number of
buds, and these buds send out sprouts when the tuber is
planted.

As a rule, the tubers are formed beneath the ground as
noted above; but in abnormal cases, or when disturbed by
diseases, the above-ground stems may produce tubers. For
example, when the fungus, Rhizoctonia, which shuts off the
downward movement of elaborated foods from the leaves to
the underground tuber-forming stems, is active, normal
tuberization under ground is interfered with and the stems
above ground will have a tendency to swell and produce
small tubers. This phenomenon is often indicative of
Rhizoctonia.

Fungus Theory of Tuberization. — In general, it is found
that darkness and low temperature favor the development
of potato tubers. Tuberization is also facihtated somewhat
by checking the growth of shoots or fruit.

There is some basis for the theory that the formation of
the tubers is associated with the presence of certain fungi.
It is certain that tuber production is encouraged in certain
orchids when the stem or root is infected with the proper
fungus. The fungus appears to check the growth of the
terminal bud and cause the development of hypertrophied
cells.

570 BOTANY 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 difficulty is now experienced in se-
curing tubers from seed because the soil has become inocu-
lated with the proper fungi. If this theory is correct, and
there seems to be some evidence that it is, the potato tuber
is in reality a gall, produced by a foreign organism.

In the potato, tuberization has been induced in concen-
trated solutions of sucrose or glycerin, etc., independent of
fungi. Similar results have occurred in the case of orchids,
onions, and radishes. From this it seems that the formatiou
of tubers may result when the osmotic pressure in the cul-
tural medium is high. However, this alone does not appear
to be the only determiner, since different results follow the
use of glucose and glycerine solutions of equal pressure. It
certainly seems that plenty of sugar must be present for
starch formation, and perhaps also for tubers to form. From
this fact, that a more concentrated cell sap is usually present
in fungi than in other plants, it does not seem unreasonable
to suppose that the role of fungi in tuberization consists in
raising the concentration of the media which they enter. It
has actually been found that cultures of Fusarium in macer-
ated potato tuber preparations increase the concentration.
In this connection, it is suggested that low temperatures and
dryness of soil may induce tuberization through increasing
the concentration of cell sap.

History. — It seems ''that the potato was cultivated and
utiHzed by the Chilean and Peruvian people before the
arrival of the Spaniards. In 1533, Pizarro found the Chileans

SOLANACE.E

;7i

using the tubers of a [)lant as their i)riiui|)al l"ot»«l. There is
no evidenee that he or his party inl roihiecl them into
Europe."

Wild plants have been found on the Peruvian coast, on
the mountains of Chile, Central America, Mexico, and
southwestern I'nited Slates. However, without a di)ul)t

Fig. 235. — The wild potato of southwest United States (SuUinam jamcsii).
(After Fitch. Colo Agr. Exp. Sta.)

tliose which were introduced into Kuroi)c were from culti-
vated plants and not from wild tuberous American species.
There is little doubt that South .\merica, in the neighborhood
of (Juito, is the place from wliich the potato was lirst intro-
duced into S])ain early in tlie Si.xleenlh cenlur_\-.

\\\cv a careful study of all possible axailablc l_\ pes and
species of Sohmiim, and a perusal of the available litrraturc
and records, F. Berthault has come to the conclusion that
.V. Iiihrrosiini is characterized and differentiated from all
other wild tuberous 5(>/'//////».v by its lloral characters, notablx'
its rotate corolla, and its cal>\ whith is always mucronati'
(sharp-pointed). All agricultural \arieties of the cultivated

572

BOTANY OF CROP PLANTS

plant (potato) have been found to correspond to these
characters.

Varieties. — There are at the present time over 500 named
varieties of potatoes in the United States. Many of these
variety names are found to belong to potatoes which are
identical in all respects. Usually, new varieties arc the
seedlings of established varieties.

The latest attempt at a classilication of American potatoes
is that of Stuart. In his ''proposed system of classilication"

^^pendertr,

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. 'J'uber, sprout
and flower characters are made the bases of distinction of
the groui)s. The student is referred to Bull. lyO, U. S.
Dei^t. Agr. (Professional Paper) for the descriptions of these
groups. Fitch has also proposed a classification using about
the same characters.
Tuber Morphology. — The [)()tato tuber is made up of a

number of zones or la\ers w
follows (Figs. 236 and 237):

1. Periderm or skin.

2. Corte.x.

3. Vascular ring.

lich are commonly grou[)ed as

SOLANACE^

573

4. External medulla.

5. Internal medulla.

According to Coudon and Boussard, these zones (except-
ing vascular ring) are proportioned (by volume) as follows:

Skin (average of two varieties)

Cortex (average of two varieties)

External medulla (average of five varieties) . . .
Internal medulla (average of five varieties) ....

Per cent.

8.79
36.19
34-I7-
14-95

-periderm

oufer
cortex

inner
~cortex

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.

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 spHt 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.

SOLAN ACE^ 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
parenchyma, and will be referred to as such in this discussion.

The parenchyma is divided into two principal parts: the
cortex, and the medulla.

Cortex.— The cortical layer of the parenchyma is just
within the periderm. It is separated from the medulla by the
vascular ring. The outer cortex is made up of smaller cells
than the inner cortex. The cells of the cortex are consider-
ably smaller than those of the medulla, and hence the density
of the cortex is greater. The cortex is darker in color than
the medulla, which is probably due to its greater density. A
thick and dense cortex indicates a potato of good quality.
A thinner, more translucent cortex is said to indicate lower
quahty. 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.

576 BOTANY OF CROP PLANTS

The internal medulla is usually more or less star-shaped.
Many of the radiating areas of internal medulla penetrate
deeply the outer medulla, some of them extending to the eyes.
In some tubers, these two zones are more or less intermixed,
with no definite zone boundaries. As a rule, in long potatoes,
the central area is very much elongated and with lateral
radiations, while in many round potatoes it is typically star-
shaped. The greater the size of the internal medulla and the
more its ramifications into the outer area, the poorer the
quality of the tuber, since it means a larger area poor in starch
and hence less mealy on cooking.

Shape.' — The common tuber shapes are round, oblong, and
elongated, in outline. One dominant form is found in each
variety but never one exclusive form. New varieties based
on tuber form are produced by a selection of tubers and are
maintained only by continued selection.

In tuber propagation, there appear among the normal-
shaped tubers a number of aberrant (diverging) forms which
are usually in the minority.

Color .^ — The common tuber colors are yellow, red, violet of
different shades, and variegated. Bluish forms are also
known. Color variation has been found in a number of
cases. In propagation by cuttings, yellow and streaked
tubers have appeared from colored ones (red and violet).
Yellow tubers have given red and violet ones, a white tuber
has given two red and two white tubers, and .one with a
bluish color has given a series white in color. The Pearl
with a brownish-white or a well-russeted skin is from the
Blue Victor which has a purple color often streaked with
white. When the white streaks cover an eye, the tubers
from the eye usually come true (white) in following genera-
tions. The People's variety, also from the Blue Victor, is a
deeper brown color than the Pearl. At the present time,

SOLANACE^ 577

white-fleshed tubers are the only ones accepted in American
markets. Yellow flesh is correlated with a strong flavor and
a poor quality, at least according to American standards.
A number of yellow-fleshed varieties from France are found
to be gummy and hard after boiling. They are considered
by the French to be of prime quality, however. In this coun-
try, these varieties are considered of good quality for the
making of salads and for frying.

Eyes (Fig. 236). — The buds of the potato tuber 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 young, but later disappears. The "eye
brow" ("eye yoke") is the line above the depression — the
line which separates the leaf from the stem. In reality, the
eye is a lateral branch with undeveloped internodes, the
whole tuber being generally a much-branched stem and not
a simple shoot. The central bud in the "eye" is commonly
the largest and strongest.

Fitch has noted that the "eye-brow" differs noticeabl^r in
vigorous and in degenerate tubers. In the latter, ittis
stronger and has a tendency to be longer.

Careful study shows that the buds or "eyes" are arranged
alternately and at the same time spirally on the tuber. Be-
ginning at one end of a tuber and proceeding toward the
other end, at the same time turning the tuber, usually enables
one to follow clearly the spiral arrangement.

The so-called "seed end," "rose" end, or "crown" of the
tuber is opposite the point of attachment to the stem.
The "stem" end is at the "base" or heel of the tuber.
The eyes are more numerous and more vigorous at the
seed end. Ordinarily, the terminal bud (at the "seed
end") is the strongest and under proper conditions will be

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
likely that the deeper-eyed plants give rise also to smooth
tubers and that in seed propagation the same results follow
as in the case of form and color.

The number of eyes varies considerably within the same
variety; in one case. Rural New Yorker, it ranges from 7 to
28; and in Early Ohio, from 7 to 22. The number of eyes
affects the quaHty, since the poorer zone of the potato (in-
ternal medulla) extends a branch to each eye, thereby in-
creasing the percentage of internal medulla at the expense
of the two outermost valuable layers.

Germination or Sprouting of Tuber. — Potatoes undergo
some changes in storage. Not only do they lose water and
decrease in weight but they increase in sugar. When sprout-
ing commences, the potato becomes sweeter, due to the con-
version of 'starch into sugar by the enzyme diastase. The
most vigorous buds are the terminal ones. The tip of the
main sprout grows upward. The underground stems bear
tubers at their ends. These will not tuber if brought to the
light 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 accordmgly. The
groups are not, however, clear-cut. Cellular density is an
important factor to consider in the breeding of potatoes for

SOLANACE^

579

table use, or for the industries. For table use, only those
tubers should be selected which have small cells (high
density), and for starch factories only those with large cells
(low density). Even with the same amount of starch in two
varieties, it is found that the large-celled one is the more
valuable to the starch industry, due to the fact that in the
small-celled varieties a larger number of the cells remain
intact and do not give up their starch in the starch-removing
process, while with the large-celled varieties fewer starch
cells escape being broken up. In France, it was found that
rich, compact (heavy) soils produced tubers with a low
cellular density, while the Hghter soils produced tubers with
small cells and high density.

Chemical Composition of Potatoes. — A number of analyses
of potatoes have been made in this country and in Europe.
Gilmore gives the results of a number of these in the follow-
ing table:

No. of No. of
analyses varieties

Quality

Cornell

Maine

U. S. all sources

France:

Condon and Boussard.

Coudon and Boussard.

136

2. 170
2. 200

2.676
2. 411

2.36s
2.090

17-356
18.037
18.400

Very good.
Very good.

. 798 Very good.
13.218 Good.
14. 118 I Passable.
16.047 Poor.

Water and nitrogen increase from the outer to the inner
zones, while the starch content decreases.

The following table showing composition of the potato is
from East:

58o

BOTANY OF CROP PLANTS

Variety

Zone

Dry
matter,
per cent.

Total N.
fresh basis,
per cent.

Total N,
dry tjasis,
per cent.

Rural

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
0.52

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 suppKed with large starch grains with infre-
quent small ones, while in other varieties the reverse is the
case. No correlation has been found between the size of
the starch grains and the size of the tuber or its total starch
content. In general, the early varieties contain large starch
grains while the late varieties contain a larger proportion of
small grains. Starch-grain formation is very slow. At first,
many small grains are found, most of which later increase in
size. This increase in size begins much sooner in early
varieties than in late varieties.

SOLANACE^ 581

In addition to starch, potatoes contain noticeable amounts
of sugar. The average quantity is not far from 0.35 per
cent. This sugar is lost in starch-making, but is utilized
in the manufacture of alcohol.

"Mealiness." — In estimating cooking quality of potatoes,
meahness is the most important consideration. Mealiness
depends quite largely upon the amount of starch in the cells.
When boiled in water, the starch grains expand and coalesce.
If there is sufficient starch, as is usually the case in the cortex,
this expansion ruptures the cell walls, freeing their contents
and producing mealiness. A deficiency of starch, as is
usually the case in the cells of the internal medulla, produces
swelling insufficient to rupture the cell walls; hence, soggi-
ness results.

As has been shown, the different zones of the potato vary
considerably in starch content, the cortex being highest,
and the internal medulla lowest. If the internal medulla
is large and has branches extending into the external me-
dulla, the tuber is likely to be hard and soggy when boiled,
and to contain zones or parts which will not mash uniformly
and readily. The external medulla is usually well stocked
with starch. When this is the case, and when the starch is
distributed uniformly, leaving no ''water areas," a high
degree of mealiness can be expected in the boiled tubers, a
condition necessary for high table quality in America.

Quality of Potatoes. — The standards for table quality in
potatoes vary somewhat in different countries. The more
noticeable differences seem to be between France and the
United States. East notes that most of the potatoes which
he examined, imported from France, had a yellow flesh, a
strong flavor, and were firm and soggy after boiling. In
France, potatoes are commonly cooked by frying in deep fat.
For this purpose, a potato yellowish in color which holds its

582 BOTANY OF CROP PLANTS

form, and is, as a result, more or less soggy after boiling, is
preferred. These characteristics are usually found in po-
tatoes which are low in starch and high in protein. In the
United States, on the other hand, where probably nine-tenths
of the potatoes eaten are boiled, a white, floury, starchy po-
tato which is mealy and dry when cooked is demanded for
table use. In Germany, table potato standards are more like
those in the United States. In general, it is considered that
for table use in thi§ country potatoes must contain about 17
per cent, or more of starch. As a result of experimentation
with 15 American varieties, East says: "It is quite evident
then that potatoes having as far as possible a homogeneous
flesh and containing as large an amount as possible of cor-
tical and outer medullary layers in proportion to inner med-
ullary layer, should be of the finest quahty."

Degree of Maturity and Quality. — Analyses in the United
States have shown that the "greater part of the total nitro-
gen is developed early in the growth of the tuber, while the
starch is stored up later." It was also found that " the starch
grains of immature tubers are small in size and few in
number." Tubers increase in desirabiHty with maturity.

Degeneracy of the Potato. — The "running out" of potatoes
is a common observation. New varieties are put on the
market, are very productive for a varying number of years,
then they usually begin to "run out" or degenerate.

In Colorado, varieties in the mountain districts do not
tend to run out, or only very slowly, the tendency apparently
being easily overcome by seed selection, while in the Greeley
district, on the plains, at an altitude of 4,600 feet, the sexual
tendencies and consequent degeneracy seem to overcome
other influences, such as selection. At Svalof (Sweden) the
opinion is held that in a variety of potatoes "there is no
period of old age." On the other hand, degeneracy is be-

SOLANACE^ 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 spindUng-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 utiHzed for seed-
ing purposes each year, the' standard of a variety may be
maintained indefinitely under all favorable conditions of soil
and climate." Hence Jt seems that the inherent tendency
to degenerate is perhaps no stronger in potatoes than in other
crops, but that they*are more widely and strongly influenced
by environmental conditions than are most crops. It is re-
ported that at Svalof the variety Dala, introduced about 150
years ago in the province of Delarne,4s[^still one of the best
sorts grown there.

Environmental Relations.— The potato is a native of the
high, cool regions of Mexico and South America. In the
United States it thrives best in a cool, moist climate as is
evidenced by the fact that the five leading potato States

584 BOTANY OF CROP PLANTS

touch the Canadian border. It is well adapted to elevation
up to 8,000 feet in the Central Rocky Mountains. Smith has
shown that the potato makes its best development in those
sections of the country where the mean annual temperature
is between 40° and 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

SOLANACE^ 585

by rasping machines. The pulp is passed through sieves,
which separate the fiber from the hquor containing starch.
The hquor is allowed to stand, and during this time white
starch settles in layers at the bottom of the receptacle. The
starch is drawn off, purified by allowing it to run over tables,
similar to those used in the purification of corn starch (page
184), and finally dried. "Culls" are profitably employed in
starch manufacture.

Alcohol. — In Germany, the potato is used extensively for
alcohol manufacture. In this country, it is too expensive
for this purpose. The process of converting the starch to
alcohol is very similar to that used in the manufacture of
alcohol from corn starch.

Production of Potatoes.' — The world's output of potatoes
in 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 1915 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
purphsh and pubescent (Fig. 239). Parthenocarpy has been
observed in this species. Artificial pollination is practiced

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

SOLANACE^ 587

Improved, Giant Round Purple) and others with white or
striped fruit (White Chinese, Long White, White Egg).

2. 5. melongena var. serpentinum (Snake Eggplant). — The
plants are medium to tall, the leaves large, and the fruit long
and slender.

3. S. melongena var. depressum (Dwarf Purple Eggplant). —
The plants are small, weak, and spreading, the leaves small,
the flowers small, and the fruit small to medium, pear-
shaped, and purple (Early Dwarf Purple).

LYCOPERSICUM (Tomato)

Habit of Growth, and Stems. — The tomatoes are annual
or short-lived perennial, coarse, branching or feebly cHmbing
herbs, that vary in size and form with the species, climate,
and methods of culture. The upright growing tomatoes
{L. 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 trailing in habit. The
pear tomato {L. pyriforme) has an erect and strong habit of
growth.

Roots. — The root system of tomatoes is fibrous and not
extensive. It does not penetrate far into the soil and is
usually short-lived.

In the transplanting of tomatoes from the seed bed to the
garden, it is the practice to allow the 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-

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
L. esculentum var. grandifolium and possibly L. pimpinelli-
folium, the leaflet margin is toothed or lobed.

Inflorescence and Flowers. — The flowers are commonly
in raceme-like cymes, or in racemes (as in currant tomato).
However, even in the currant tomato the racemes are often
branched at the tip. The flowers are perfect, regular, and
pendant. The calyx is five- to six-parted; the segments are
Hnear or lanceolate, persistent, and increase in size with the
development of the fruit. The corolla is rotate or wheel-
shaped, cleft into usually five, sometimes more, lobes; the
tube of the corolla is short. There are five stamens (some-
times more) attached to the corolla tube; the filaments are
very short, and the anthers open by a longitudinal sHt 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 possibiHty 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-poUination
seldom occurs.

SOLANACE/E 5^9

Extensive experiments made by Fletcher and Gregg with
f^reenhoiise or forced tomatoes showed that self-fertiUzed
blossoms set fruit as well as cross-fertilized ones. Further-
more, there was practically no difference in the appearance
or weight of the fruit, and no difference in the number of cells.

Parthenocarpy.— This phenomenon is not at all uncommon
in tomatoes. By this is meant the ripening of the fruit
without the fertilization of the ovules. Such fruits, of
course, possess no gcrminative seeds.

Abnormal Tomatoes. — Munson has found, in crossing
tomatoes, that the amount of pollen placed on the stigmas
affects the size of the fruit. Two stigmas in the same flower
chister were given different amounts of pollen: one abun-
dant i)olIen, the other lo to 20 grains. With plenty of
pollen, normal fruit resulted, while with scanty pollen, small
and fleformed 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 sui)ply
of pt)llen.

The Mature Fruit— The fruit is a true berry (Fig. 240).
The wild form of our common garden tomato US', csniloiluni)
has a two-celled fruit with a rather (lr\- placenta. 'i"he cells
are delinite in both number and shape. C'ultixaled tornis
of the common garden tomato have a number ol cells in the
fruit; thev are indehnite in both nuinl)er and shape, and the
placenta is exceedingly lleshy. The fewest celled fruits are
eonsi.lered nean-st the original tyi)e. The pear and cherry
tomatoes l)oth have two-celled fruit, 'i'he calyx is persist-
ent, adhering to the base of the fruit. The fruit \aries in
shape, color, and smoothness of surface. The seeds are
numerous and small.

59°

BOTANY OF CROP PLANTS

Geographical. — All the species in this genus are natives of South America.
iJunal, in DeCandoUe's Prodromus, gives lo species of Lycopersicnm; 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

but two cultivated species of Lycopersicnm: L. esculenluni,
the common tomato, and L. pimpincllijolinin, the currant
tomato. L. esculenlum is, according to Bailey, dixided itUo
the following varieties:

1. L. esculenlum var. vulgare, garden tomato.

2. L. esculenlum var. cenisiforme, cherr}- tonuito.

3. L. esculenlum var. l)yriformc, pear or plum tomato.

4. L. esculenluni var. validum, upright tomato.

5. L. esculenluni var. grand if olium, large leaf tomato.

L. pimlyincllifoliuni is not subdi\idcd. On the other hand,
'I'rai}' regards as distinct species: L. pimpinellijolium, L.

SOLAN ACE^ 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 understood.

Key to Types of Cultivated Tomatoes

Fruit in long racemes or branched clusters; berries red, currant-like, Currant,

German, raisin or grape tomato.
Fruit in short racemes or branched clusters.

Plants low, stiff, and erect, having much the appearance of a potato plant;

leaves small, curled, Upright tomato.
Plants taller, the branches weaker and more spreading.

Leaves very large, about two pairs of almost entire-margined leaflets,

Large-leaf tomato.
Leaves of medium size, numerous 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 H to ^i inch in diameter,

two-celled, Cherry tomato.
Fruit varying somewhat in shape, surface, and color, larger than
preceding, many-celled. Common garden tomato.

The common tomato (var. vulgare) has undergone consid-
erable modification as the result of cultivation. As compared
with the small two-celled fruit, with thin walls and a dry
placenta, and in some instances with distinct grooves on the
surface, the cultivated forms are larger, many-celled, the
walls and placenta are thick and fleshy, and the fruit surface
smooth. There are three general groups of the common
tomato: fruit angular, fruit apple-shaped, and fruit oblong.

The cherry tomato (var. cerasiforme) has small globular,
red or yellow two-loculed fruit. The pear tomato (var.
pyriforme) has small red or yellow, two-loculed pear-shaped
fruit. The upright tomato (var. validum) looks much like
the potato plant in its growth habit. The large-leaf tomato

592 BOTANY OF CROP PLANTS

(var. grandifolium) , 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 {Phymlis pubescens) and the
strawberry tomato {Physalis pubescens and P. alkekengi) are distinguished
from Lycopersicum spp. in that the calyx becomes enlarged, inflated, and en-
tirely covers the srtiall 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 SolanaCeae, but may be distinguished from Lycopersicum by its woody
habit of growth.

History. — The tomato is still fomid 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

SOLANACEJE

593

ovate and entire. The flowers (Fig. 241) are solitary, or
in twos or threes. The ri7/v:v is five-lobecl, truncate, obcon-
ical, cup-shaped or funnel-
form. The corolla is white,
rotate, usually ilve-lobed,
with the lobes valvate.
There arc five sUimcns, some-
times si.\ 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 shajK'.
are main' seeds in each fruit.

longitudinal
section of pepper flower (Capsicum
annuum). X 2.

There

I'l lengthwise sections of the fruit of pepper (Capsicum
annuum;.

3^5

594

BOTANY OF CROP PLANTS

Geographical. — This species has never been found wild. But it is quite well
established tiiat the entire genus Capsinim had its origin in tropical America.

Fig. 243. — Fruits of peppers (Capsicum annuum). A, Oxheart (C.
annuum cerasiforme) ; B, Cherry (C. annuum ccrasifera) ; C, Celestial (C. an-
nuum abbreviatum); D, Chilli (C. annuum acuminatum); E, Long Cayenne
(C. annuum acuminatum); F, Long Yellow (C. annuum longum); C, tabasca
(C. annuum conoides); //. Sweet Spanish (C. annuum grossum) ; /.Ruby
King (C. annuum grossum); /. Bell (C. annuum grossum); K, Squash (C.
annuum grossum). {Afler Irish.)

Tlie temperature requirements of peppers arc similar to those of eggfiiants
and tomatoes. Their season of growth is so hmg tliat they .irr unalile to

SOLAN ACE^ 595

produce a full crop before frost, except in the Southern States, unless started
under glass.

Other 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 tj'pes 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}i inches long; peduncles about as long or longer,
C. annuum conoides (Coral Gem, Tabasco, Cayenne, Orange-red
Cluster).
Fruit usually more than i}-i inches long; peduncles shorter.
Leaves and fruit fascicled; fruit erect, C. annuum fasciculahim (Red

Cluster, Yellow Cluster).
Leaves and fruit not fascicled, C. annuum acuminatum (Chilli, Long
Cayenne, Nepal Chili).
Calyx not usually embracing base of fruit, except in the Ivory Tusk variety,
C. annuum longum (Black Nubian, Long Red, County Fair, Cardinal,
Long Yellow, Ivory Tusk).
Fruit oblate or oblong, truncated, deeply lobed, furrowed and wrinkled; flesh
mild, K 2 to ^i 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; caly^ not embracing base, C. annuum abbreviatum (Celestial, Etna,
Kaleidoscope, Red Wrinkled, Princess of Wales).
Fruit generally smooth, oval, spherical, cherry or heart-shaped, % to i)^
' 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

596 BOTANY OP CROP PLANTS

Cherry) the pungency is in the pericarp as well as in the pla-
centa and seed. In larger varieties (Squash, Bell, Sweet
Mountain), the pungent taste is located for the most part
about the seeds, while the fleshy pericarp is "mild."

Uses. — Medicinally, the red pepper is used in a great
variety of ways. Probably its most important use is as a
condiment, Cayenne Pepper being the common form. This
is made by grinding up the entire fruit to a fine powder.
Pepper sauce is the unground fruit preserved, in brine or
strong vinegar. Tabasca Pepper and Tabasca Catsup are
examples of this. Chilli con carne is a mixture of small,
finely ground peppers and meat. Peppers are commonly
used in tamalas, also in pickles and salads, while bell-shaped
and squash varieties are used as mangoes. Some varieties,
such as Little Gem and Prince of Wales, are grown for orna-
mental purposes.

NICOTIANA (Tobacco)

Habit. — Most representatives of this genus are tall, stout
herbs. Several (as N. glauca and N. tomentosa) grow to a
height of 10 feet or more. S. wigandioides is half-shrubby.
They are annual or perennial in habit, and for the most part
sticky-pubescent; they have a strong odor, and narcotic,
poisonous properties.

Leaves.' — The leaves are simple, alternate, mostly large,
entire or wavy along the margin, petioled (in 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, purphsh, or rose.
The calyx is synsepalous, five-cleft, and usually persists in
the fruit. The corolla is salverform or funnelform, five-
lobed, and the tube is longer than the limb. There are five

SOLAN ACE.E 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. tabacum (tobacco) is the only one of great commer-
cial importance.

NICOTIANA TABACUM (Tobacco)

Habit, 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 quahty of the leaves is
damaged by their growth. The "one-sucker" type of
tobacco is one that throws out one or only a few suckers.

Leaves. — There is great variation in the shape, color, tex-
ture, and number of leaves. In cigar-wrapper tobaccos, the
leaves are thin, fine in texture, and small-veined. The
leaves of plug and pipe tobaccos are usually coarser, thicker,
and tougher. The leaves are sessile, decurrent, and either
narrow or broad, most commonly lanceolate or ovate, and
pointed. The number of leaves on a plant, which is, of
course, important commercially, is different in the various
types and also varies considerably from plant to plant in the

598 BOTANY or 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 maUc
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-

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 Slrasbiirger.)

Fruit.^ — The fruit (Fig. 244) is a two- to four-valved cap-
sule, bearing numerous small seeds. A single plant may
produce as many as a million seeds.

Geographical. — This species is indigenous to tropical South America. Its
varieties are now in cultivation throughout subtropical and even temperate
climates. It occasionally escapes from cultivation and runs wild. It is
grown commercially only in the humid sections of this country.

6oO BOTANY OF CROP PLANTS

Closely Related Species. — There are a number of species of Nicotiana which
resemble N. tahacum somewhat, and there are several species belonging to
other genera besides Nicotiana that go by the name "tobacco."

N. ruslica 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 Duboisia hopwoddii, a species of Solanacea. "Indian"
or "wild tobacco" is a name often given to Lobelia inflata, the dried leaves
and tops of which are officinal. It is a member of the bellflower family,
CampanulacecB. Arnica alpina, a composite, is sometimes known as "moun-
tain tobacco." The most popular ornamental Nicotiana is N. alata. In it
the flowers are white, open at night and closed in the daytime.

Types arid 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 country 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

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 fertihzers, and are so used in tobacco sections.
Curing Tobacco. — This process consists in removing the
moisture in the leaves and stems in such a manner as to
produce a uniform color and texture in the leaves. Artificial
heat was first employed in the curing of tobaccos in 1812.
Wood fires were used up to the year 1828, about which time,
flues, and charcoal fires came into use. Flue-curing entirely
replaced charcoal fires in 1865. Flue-curing produces a
bright yellow leaf. The green tint is obtained by harvesting
the leaf before it is fully ripe. The dark export tobaccos are
cured with open hard-wood fires. Light tobaccos may be
air-cured, and such are used for pipe smoking, and cigarettes.
White Burley tobacco, so highly prized for twist and plug
chewing tobaccos, is usually air-cured. The yellow and
mahogany tobaccos are cured by flues. The process takes
about four days. The broad leaf and Havana seed leaf
varieties of the Connecticut Valley are air-cured. They are
domestic cigar' tobaccos. Curing is often carried on in
specially constructed barns with horizontal ventilators. It
usually takes about two months to air-cure tobacco, and
less time if artificial heat is used. After the leaves have been
left hanging for a long time, they are packed closely in boxes,
where they are left undisturbed for several months. When
warm weather sets in, a process of fermentation is set up in
the cases, during which process certain important changes
take place. Fermentation may be brought about after a
shorter period of drying than is used in the preceding
method, by placing the leaves in piles in a warm, moist at-
mosphere. When the temperature reaches 125° to i3o°F.,
the piles are opened and heaped up again. The piles are

6o2

BOTANY 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 191 5 is shown in the following table :

Tobacco: Acreage, Production, and Total Farm Value,
by'States, 1915

Kentucky

North Carolina.

Virginia

Ohio

Tennessee

Pennsylvania. . .
South Carolina. .

Wisconsin

Connecticut

Maryland

All other States
United States...

Farm valu
Dec. I,
dollars

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

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

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 19 14, 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:

306-31S, 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: 355-357, 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, 191 1.
Fitch, C. L.: Productiveness and Degeneracy of the Irish Potato. Colo.

Agr. Exp. Sta. Bull. 176: 1-16, 1910.
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, 1915.
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.
Meckel, E.: Sur I'origine 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. Card., 53-110, 1898.
Jones, Donald F.: Natural Cross-pollination in the Tomato. Science, n. s.,

43: 509-510, 1916.
Klemt, F.: t)ber den Bau und die Entwickelung der Solanaceenfruchte.

Berlin, 1907.

SOLANACE^ 605

Magrou, H.: Symbiosis and Tuberizatioa in Potato. Compt. Rend. Acad.

Sci. (Paris), 158: 50-53, 1914.
MiDDLETON, R. Morton: Solanum Tuberosum L., and Its. Allies. Jour.

Bot., 47: 228, 1Q09.
Reed, T.: Tbe Anatomy of Some Tubers. Ann. Bot., 24: 537-548, 1910

(Potato and Jerusalem artichoke).
Rendle, a. B.: Production of Tubers within the Potato. Jour. Bot., 31:

193-19S, 1893.
Rigdway, Charles S.: Grain of the Tobacco Leaf . Journ. Agri. Research,

7: 269-288, 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, 1915.
WiTTMACK, L.: Die Stammpflanze unserer Kartoffel. Landw. Jahrb., 38:

551-605, 1909.
Studien iiber die Stammpflanze der Kartoffel. Ber. Bot. Gesell., 27: 28-

42, 1909.

CHAPTER XXXIX
CUCURBITACEiE (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 [Echinocystis lohata) 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.

H'.abit.— 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.

Steins 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

CUCUIU3ITACE/E

6o7

late, and usuall\' has il\e iml)ricate(l lobes. The corolla is hve-
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, hut they often grow

Fig. 246. — -Field pumpkin (.Cucurbita pepo).
late flower.

staminate flower; B, pistil-

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 makinii; in all Uvv anther cells to tln'
andrcecium. The lilaments are short, often united, and

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 />//// is a jK'po. usually indchiscent, or in some

Fic. 247. — Field pumpkin (Cucurl)il;i p
iKito llciwcr; hoth will

flower; /5. si aini-

cases (M icniDi pelts. Cytiautlicra) dehiscent at the apex or
bursling irre.L,ailarl\-. In many instances (watermelon,
I)umpkin. s(|uash). llu- Iruit is of enormous si/e. The outer
pari (»r the fruit is reie[)lacle which has biHome altatlu-d to
the exocarp. Tht- th-sh of the frnit i> chirll_\- mcsotarj) and

CUCURBITACE/E

609

Fig. 248. — Cross-scclinii ci niaiunj I'ruil of cucumber (Cucumis sativus).

Fk;. 249. — (;.i'niiinati.,u , ,( pumpkin 1 Hi;,' Tmhu .,_■,■, i,.' ,h..\vinK' llu'
pegs functioning in the removal of the co;its. (AjUr Crocker. Knighl and
Roberts.)

6 10 BOTANY or CROP PLANTS

endocarp. Seeds are usually abundant, ilat. and without
endosperm.

Germination of Cucurbit Seeds. -The cotyle(K)ns are
epigean in all the common members of the Cucurbitaceie.
There are a few hypogean forms, such as MegarJiiza calif oniica
and Sicyospeyma gracUis. 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 hypocotyledonar\- arch,
there is developed a peculiar outgrowth known as the " prg.'^
It is a natural part of the plant, and although it \arics some-
what in size in dilTerent cucurbits, it has been shown that
gra\ity has no direct effect in increasing peg de\el<)[)nient
or in determining its lateral placement on the hyi)()cotyl.
The peg serves to hold the seed coat while the hy[)oc()lyl
withdraws the cotyledons from the coat. It will be noticed
(Fig. 249) that one edge of the ^cc(.\ coat is caught against the

Key to Principal Genera

C(jrolla rotate or campanulate, five-parted to or almost to the base.

Tendrils often two to three times branched, Cilrulliis (watermelon, citron).

Tendrils simple, Cncumis (muskmelon, cantaloupe, cucumber).
Corolla campanulate,' fivc-lobed to or little below middle Ciicurhild (j,'ourd

pumpkin, squash).

CUCURBITA (Squash, Pumpkin, Gourd)

Stems, Leaves, Flowers. — Members of this genus arc
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 scjuashes
(Turban, Marblehead, Canada Crookneck, Field Pumpkin).
The tendrils are branched. The leaves are usually cordate
at the base, lobed (C. pepo), or not Ujljcd iC. ffiaxinia).
The jlou'crs are alwa}'s solitary in the a.xils of the lca\es,
yellow, and monoecious. In squashes with a bushy habit

CUCURBITACE^ 6tt

(early squashes), the staminate flowers are on long peduncles,
while the pistillate flowers occur near the base of the plant
on comparatively short peduncles. In the long-running
squashes (fall and winter types), the staminate 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 campanulate 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 staminodia 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 pistiflate.

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

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. — A, 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.).

CUCURBIT ACE^ 613

CUCUKBITA PEPO

Description. — This is an annual species, with long, running
stems; in the so-called "bush-pumpkins," which include the
scallops (patty-pans or cymblings) 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. — Cucurhita 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 pally-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 Cucurhita pepo.
In addition to this species, they are also referred to Lagenaria
vulgaris, Lufa, Cucumis dipsaceus, Cucumis anguria, and
Benincasa c&rifera.

6l4 BOTANY OF CEOP PLANTS

CUCURBITA MAXIMA

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.

Type 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-cap." 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 mo^t 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.

CUCUEBITACE^ 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 fruii 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, Cucvimber)

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

6l6

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 ovules
numerous. The fruit is a pepo varying in shape, size, sur-
face characters, and physical and chemical composition.

Pollination. — Grifhn gives data with reference to pollina-
tion and fruiting of the cantaloupe. He kept an account of

CUCURBITACEiE 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 3,075 253

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
earHer than the pistillate ones. Pollination is carried on by
insects. Ordinarily, lack of fertilization causes a premature
dropping of the fruit, and incomplete fertiHzation results in
misshapen fruit.

Geographical.— There are cldse to 30 species of Cucumis, 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 melo (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>^ inches long, Cucumis anguria (prickly
cucumber. West Indian gherkin, Jerusalem cucumber, gooseberry gourd).

6l8 BOTANY OF CROP PLANTS

CUCUMIS MELO (Muskmelon, Cantaloupe, Melons)

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 fruit
varies in shape and size.

Cucumis 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 fertihzed 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-tinted (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 Rockmelons {Cucumis melo 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

CUCUrtRITACE.E

619

twisted, furrowed, and thickest at tlu- distal end. It often
reaches a length of 3 feet, and a diameter of i to 3 inches.

Fk;. 25.5. — 1 to 0, sUij^us ill tli(j licvolopnient ot ihe cucumber fruit; tlx'
(lower is unopen in r 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,
staniinate flower of cucumlier.

5. Ulnlcr Melons (CiicKmis mrlo var. inodorns).- LiiUc
known in United States.

620 BOTANY OF CROP PLANTS

6. C IK umber Melon {CuciiDiis nuio var. acidnlns). — Of no
economic importance.

7. Orange Melon. Maiiii^o Melon, }[cloii Apple, Vine Peach,
Garden Lemon, Vegetable Orange (Cuciuius mclo var. chito). —
Used in making preserves.

8. Dudaim Melon, Pomegranate Melon, Queen Anne's
Pocket Melon {Cucumis mclo var. dudaim). — Inedible.

CUCUMIS SATIVUS (Cucumber)

Description. — 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 })e
crossed with the melon. Experiments have shown that this
crossing is impossible. The fruit is oblong, obscurely threc-
anglcd, tuberculate when young, but often becoming smooth
(in cultivated forms) at maturity.

Geographical.— Cucumljcrs have been in cultivation for 3,000 or 4,000
years. Thcj' 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 sativus). Chief of these are
the snake cucumber (Cucumis mclo var. flexuosus). West
Indian gherkin {Cucumis anguria), musk cucumber {Cucumis
moschata), and star cucumber {Sicyos ungulalus). The snake-
cucumber is in reality a melon. It is characterized b>- 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

CUCURBIT ACE^ 6 2 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

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)

Description. — This is an annual, creeping, branching
plant. The stems are slender, rough-hairy, and bear simple
tendrils. The leaves are deeply sinuate-lobed. Staminate
flowers are small, numerous, and on short peduncles, while
pistillate flowers are on long stalks. The fruit is about ij^^
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. s ativus) a,re often substituted
for them, however.

CITRULLUS (Watermelon, Citron, Colocynth)

Description. — Citrullus species are coarse, trailing herbs
with branched tendrils. The leaves are rotund-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 flowers, 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.

CUCURBITACE^ 623

Geographical. — There are two or three species of Citrullus, 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 (Watermelon, Citron)

Description. — The watermelon is a hairy annual with
long, angular, somewhat branching stems, 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 purpHsh, 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.

Types 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 soHd. 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."

624 BOTAiSTY 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 Georgia, Orange,
Triumph); and (6) mottled green (Nabob Phinney's Early).
These "classes" are subdivided into "types" according to
shape of fruit, arid the "types" are each divided into two
groups: those with light seeds, and those with dark (black
or 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, 1910.
Griffin, 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.
IT. Classification of Watermelons. N. H. Agr. Exp. Sta. Bull. 86: 95-107,

1901.

CHAPTER XL
COMPOSITE (Thistle FamUy)

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:
union of petals (sympetaly), inferior ovary (epigyny), seed-
Hke fruit, pappus, united (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 artichoke, endive, salsify, and dandelion. The
following is a short list of the less important representatives
of the family: yarrow {Achillea), Chrysanthemum, 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

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.

COMPOSITE

627

Flowers.— The flowers may be perfect, polygamous,
monoecious or dioecious. There are two sorts of flowers in
the composite family: (i) Disk or tubular, and (2) ray or
ligulate.

Disk Flowers (Fig. 254, C).— These are perfect and regular
and make up the so-called disk of the composite "flower."
For example, the disk of the "sunflo.wer" 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 mstances, 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 TuhuliflorcB. The dandelion, chicory, and
lettuce are representatives of the former, and sunflower,
Jerusalem artichoke, daisy, fleabane, aster, and goldenrod
typical members of the latter group. In the Liguliflorce,
ligulate or strap-shaped flowers are the only sort present; in
these, the flowers are perfect and consist of five stamens with
their anthers united into a tube, a one-celled, one-seeded
ovary, a single style, and a two-lobed stigma; the pappus may

628 BOTANY OF CROP PLANTS

be present or wanting. In the TuhuliflorcB, 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 Tuhiliflorce, the
ray or ligulate flowers are very frequently pistillate. In
both types of flowers, the fruit (achene) is one-seeded and
indehiscent. The pappus is usually persistent at the apex
of the fruit, serving as a means of dissemination by the
wind.

Key to Important Genera

Flowers with ligulate corollas only; flowers perfect.
Pappus of plumose bristles, Tragopogon (salsify).
Pappus not plumose.

Pappus of mere chaffs or these reduced and united into a crown,

dehor ium (chicory).
Pappus of capillary bristles.

Achenes flattened, Lactuca (lettuce).
Achenes not flattened, Taraxacum (dandelion).
Flowers with tubular corollas or none, or only the ray flowers with ligulate
corollas.
Anthers long- tailed at the base and with long appendages at the tip; heads

large; rays none, Carduus (thistle).
Anthers not tailed at the base; flowers tubular only, or tubular and ligulate.
Receptacle naked.

Ray flowers yellow; involucral bracts scarcely imbricated, Arnica.
Ray flowers never yellow; involucral bracts well imbricated.
Bracts of involucre imlaricated in several series. Aster.
Bracts of involucre in but one or two series, Erigeron (fleabane).
Receptacle chaffy.

Bracts of involucre foliaceous, Helianthus (Jerusalem artichoke and

sunflower).
Bracts of involucre dry, thin, and papery.
. Receptacle chaffy, Achillea (yarrow).
Receptacle not chaffy, naked, or sometimes hairy.
Ray flowers present. Chrysanthemum.
Ray flowers none, Artemisia (sage and wormwood).

COMPOSIT.E

629

LACTUCA SATIVA (Garden Lettuce )

Description. Coniiiion garden IclUue is a tall, annual
leafy liefh, with a niilk\- juice. There is llirown up from
a short stem early in the season a cluster of leaves varying
consideralDly in shape, character, and color, in the different
varieties. Later in the season, a "seed stalk" is sent up.
Tracy found that, at Washington, I). C, the first appearance

Fig. 255. — Asparagus lettuce, var. angustana. {Aficr CorbcU.)

of the seed stalk after sowing seed, varied from 59 (in
Emperor Forcing) to H2 (in Italian Ice) days. The leaves
are alternate, denticulate or pinnatifid, sessile or auriculate-
clasping, sometimes spinulose-margined, the lowest ones
larc^e, and the upper much smaller. The inflorescence is a
panicle. The flowers are yellowish or )-ellowish-white, the
involucre cylindric, the bracts of which are imbricated in
several series, the outer shorter. 'Hie receptacle is tlat and
naked. The corolla rays are truncate and tive-toothed at

6^0

BOTANY OF CROP PLANTS

llu- end. 'I'lu' anllicrs are sa.G;itlatc at the base. The style
branches are slender. 1'he (ichriics are oxal. oblont:;, or
Hnear, tlat. three to ti\e-ribbed on each l;ui\ narrowed above
or contracted into a narrow beak which bears a hiru;e number

Fic. 256.- r

\fh-r Corln-ll.)

of soft, capiUary, white or brown pap[)us bristles. The
achenes \ary in color: whitish, blackish, yellowish, or
brownish.

Origin, and Geographical. It is quite generall\ conteded
by botanists that our garden lettuce (L. saliva) is originated
from the wild species, L. scariola. This latter species grows

COMPOS IT. F-

631

wild in Europe. Canary Isles, Madeira, Algeria, Abyssinia,
and Eastern Asia, and has also become naturalized in the

Fk;. 2.S7. ^-Cos lettuce, var. romana. (Aflrr Corhcll.)

liiiled States, where it is often a troublesome weed. In
this eountrv, L. scariola is distributed from New York to

Fig. .'sS.-Hcad Ictlucc, var. capitata. {After Corlnil.)

Minnesota and Missouri. The close relation.ship between
/.. saliva and/., scariola is shown by the fact that they readily
cross.

032 BOTANY OF CROP PLANTS

There are a number of native species of Lactuca in this
country. Britton and lirown mention eight species native
of the eastern and northern United States, besides the intro-
duced L. scariola. This hitter species is commonly known
as the "compass plant."

Fu;. 259. — Salsify (Tragopogon porrifolius). From left to right: unopcr.
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 nui}' be tlis-
tinguished by the following artificial key:
Kl:y to Tyl>i:s of Li:TTi;cii
Basal IcaN'cs narrow, distinctly lanceolate, L. saliva \ar. anguslana (asparagus

lettuce).

COMPOSITvE

633

Basal k-avcs l)n)a(l, spal
Leaves deeplv ml 01

ulalo, oval t.) roun-lish, always rounded at the tip.
1 ..11 liie cd^rs, L. idtiv'i var. itilyhacca (culling or cut -
leaved lelUm).
Leaves entire or but slightly toothed. , • , , , >

Leaves forming a rather compacl roundish or llalt.sh head; leaves ncvu
d c cle Iv SI IT and Hat, L. saii.a var. capU.ia (hea.l or cabbage ellucc)
Leavel forming a conical or cylin.lrical-shaped head; leaves slra.ght and
slilT L. Siit'mi var. romana (,cos lelluce).

Fi(.. 260.

pappus

-SinKlc llowcr of salsify (Tragopogon p..rrif.jUus). X -M..

'I'racy classifies the American varieties of lettuce as tol-
lows: (r) butter varieties, (2) crisp varieties, and (.^) os
varieties. These three groups are further subdivided.
TRAGOPOGON PORRIFOLIUS (Salsify or "Oyster Plant")

Description.-Salsify is a hardy perennial plant hnu^ a
tleshy r.).)t. The rools are about 12 inches Ion- wilh a
(liam'eler of about 2 inches at the top; the skin is grayish
white The sloLs are usually somewhat branched and succu-
lent Wiien grown from seed, a seed stalk is sent up the
second season to a height of 2 to 4 feet. The lonrs are alter-
nate, entire, Hnear-lanceolate, clasping at the base, and glau-
cous. Heads (Fig. 259) are single at the end of rather long
thickened peduncles, which are often holhnv for several

634 BOTANY OF CROP PLANTS

inrhcs below the head. The heads are purple and open
earl}' in the iiiorninjj; but usually close by noon. The in-
volucrc is cylindrical, the bracts nearly ecjual. in one series,
linear-lanceolate, and usually much longer than the rays
of the llovvers. The corollas (Fig. 260) are truncate and tive-

Fiij. 261. — Salsify (Tragopogun purrifolius). Hcadiu fruit; receptacle
after having shed the achenes; single achene.

toothed at the apex. The anthers are sagittate at the base.
The style branches are slender. Achcncs are linear, and termi-
nated by slender beaks, the outer ones being covered with
tubercles, particularly on the ribs below. The pappus is
grown together at the base, is plumose, and has interwebbed
branches (Fig. 261).

COMPOSITE 635

Geographical, and Closely Related Species.— The species
is a native of southern Europe. It is quite widely distributed
in this country in fields and waste places, probably as an
escape from cultivation. A yellow-flowered salsify (r.
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 m_ember 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 cauHne
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 intybus (chicory) and
Cichorium endiva (endive). . ■

636 BOTANY OF CROP PLANTS

CICHORIUM INTYBUS (Chicory or Succory)

Description (Fig. 262). — This is a perennial species from a
long, deep tap root, which sends up a stiff, rough-hairy,
branched stem to a height of i to 3 feet. Radical leaves are
numerous, and spreading on the ground; the upper leaves
are smaller, lanceolate or oblong, lobed or entire, clasping
and auricled at the base. The heads are axillary. The
flowers are blue or purplish, and sometimes white.

The species is a native of Europe. It is introduced into
the United States, occurring as a ruderal from Nova Scotia
to North Carolina, and west to Minnesota and Missouri.

Uses, and Varieties. — The roasted root of chicory has been
used as a substitute for, and an adulterant of, coffee. The
young roots are sometimes boiled, and the leaves used as
"greens" or served fresh as a salad. The plant is some-
times forced in the winter to produce a cluster of loose
leaves for use in salads. Such clusters of leaves are called
"Barbe de Capuchin." Common varieties of chicory are:
Common, Large-rooted Madgebury, Long-rooted Brunswick
and Improved very Large-leaved. Witloof chicory is an
improved variety of Belgian origin.

CICHORIUM ENDIVA (Endive)

Description. — Endive is an annual or biennial herb with
numerous basal leaves which vary much in character; they
may be merely toothed, the teeth large or small and numerous,
or pinnatifid; some of the most desirable varieties have the
leaf margins very much curled. The upper leaves are smaller,
and auricled at the base. The stem often rises to a height
of 3 feet; it is hollow, terete, branched, and smooth or
slightly hirsute. The flowers are purple and sometimes white.
The achenes are angular and ribbed.

COMPOSITiE

637

Fig. 262. — Chicory (Chicorium intybus). A, sessile clusters of flowers in
axils of bracts, Xi; B, single floral bract enlarged, X 4; C, open flower, face
view, enlarged; D, basal leaf, X i>^.

638

BOTANY OF CROP PLANTS

Geographical Distribution, and Economic Uses. — Endive
is a native of India. It is cultivated to a great extent in
the gardens of European countries and to some extent in

Fig. 263. — Tubers of Jerusalem artichoke (Helianthus tuberosum). {After
Vilmorin.)

the United States. The best-known variety grown here is
the Green Curled. The plant is cultivated for the young
basal leaves which are blanched and used as a salad.

COMPOSITE 639

HELIANTHUS TUBEROSUS (Jerusalem Artichoke)
Description.— The Jerusalem artichoke is a perennial herb
arising from thick, fleshy rootstocks that bear oblong tubers
(Fig. 263). The above-ground stems attain a height of 6 to 12
feet; they are stout, branching, terete and hirsute. The leaves
are alternate above, opposite below, simple, ovate or ovate-
oblong, firm, three-nerved at the base, narrowed, rounded,
truncate or slightly heart-shaped at the base, acuminate at
the apex, and long petioled. The heads are solitary or in
corymbs. Tubular (disk) and hgulate (ray) flowers are both
present; the rays are yellow and the disk is also yellow (Fig.
254). The involucre is hemispheric, with lanceolate, acumi-
nate hirsute or cihate, squarrose bracts. There are 12 to 20
rays. The receptacle is chaffy; the chaff subtends the disk
flowers. The 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. Composite.
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.

GLOSSARY

Abaxile. — Situated off the axis.

Abortive. — Imperfectly formed or rudimentary.

Acaulescenl. — Without an obvious stem.

Accumbent (cotyledons). — Their edges against the hypocotyl.

Achene (akene). — A one-celled, dry, indehiscent fruit in which the testa
and pericarp are not firmly attached.

Aero petal. — Developing from the outside (below) toward the inside (above).

Actinomorphie. — Regular, ray-shaped; said of a flower when it can be
divided into symmetrical halves by radial planes.

Aeuminaie. — 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.

Amphitrcpous (ovules). Half-inverted and straight, with the hilum about
the middle, and micropyle terminal.

Anatropous (ovules). — Inverted, straight and with micropyle next the
hilum.

Androecitim. — 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

642 BOTANY OF CROP PLANTS

Awned. — Furnished with an awn cir 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. — Knob-like; shaped like a head.

Caprification. — The artificial process of pollinating figs.

Capsule (pod). — A dry, dehiscent fruit of two or more carpels.

Carina. — Keel.

Carpophore. — A slender stalk to which the mericarps of the umbelliferous
fruit are attached.

Caryopsis. — Synonym of grain — a 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.

Caulijlcrus. — Stem-flowering; trunks bearing flowers, as in figs.

Cauline. — Pertaining 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.

Coleoptile. — ^Leaf sheath in grasses.

Colecrhiza. — A sheath about the root.

Commissure. — The contiguous surfaces of two carpels, as in the fruit of
Umbelliferas.

GLOSSARY 643

Conduplicate. — Folded lengthwise.

Connivent. — 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.

Crenulate. — With very small rounded teeth; diminutive of crenate.

Culm. — The hollow stem of grasses and sedges.

Ctilicle. — 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.

Denticidate.— 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.

Diclinism. — 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.

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. — Young plant within the seed.

Endocarp. — Inner wall of pericarp (ovary wall).

Endosperm. — The stored food supply in a seed.

Entire. — Without divisions, lobes, or teeth; usually refers to margins of
leaves, petals, and sepals.

Epicalyx. — Extra bract-like segments below the calyx in the strawberry.

Epigynous. — Ovary inferior; flower parts above the ovary or apparently
growing from its tip.

Epiphyllous. — Borne on leaf surface.

Epiphyte. — Growing upon another plant, but gaining from it no nutriment.

Episperm. — Testa; seed coats. .

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; apphed 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-hke in form and texture.

Follicle. — A dry, dehiscent fruit with one carpel which splits along the
ventral suture.

Funnelform. — Funnel-shaped.

Geitonogamy. — A method of pollination in which pollen is taken from anther
to stigma of another flower on same plant.

GLOSSARY

64s

Geniculate— Bent abruptly at an angle, like the bent knee.
Glabrotis.— Smooth; without hairs, scales, or bristles.
Glandtdar. — Furnished with glands.

Glaucous—Covered with a fine, waxy-like covering (bloom) which rubs
off easily.
Globose. — Globe-shaped.
Glob^llar. — Globe-shaped.

G/Mwe.— General name for floral bract of grasses and sedges.
Gyncecium. — The carpels taken collectively.

fl"a<r/o<e.— Halberd-shaped; basal lobes diverging.

Head— An indeterminate type of inflorescence in which the flowers are in
a dense cluster, as in Composite.

Hermaphrodite (flowers).— Perfect, both stamens and pistils present.

Hyaline. — Thin and very nearly transparent.

Hypocotyl.—Tha.t portion of the embryo stem below the cotyledons.

Hypogean (cotyledons).— Remaining underground, as in the pea.

Hypogynojis.~Ova.Ty superior; flower parts attached below the ovary.

Hilum.— The scar on a seed, marking the attachment of a seed to its stalk.

Hirsute.— CoveTed 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.

Inflexed. — Bent inwards.

Inflorescence. — A flower cluster.

Integument. — Skin; coat or protecting layer.

Internode. — The interval between two adjacent nodes.

Intravaginal.—'Keiexnng to branches in grasses which grow out between
the leaf sheath and the culm (stem).

/w/^-or^e.— Turned inwards; usually referring to anthers which shed their
pollen towards the inside of the flower.

Involucel. — A secondary involucre.

Involucellate. — 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.

646 BOTANY or CROP PLANTS

Keel. — Ridge, like the keel of a boat.

Laciniate. — Cut into narrow, rather deep segments.

Lamella. — Plate.

Lanceolate. — Lance-shaped.

Lemma. — The bract (glume) at the base of the flower in grasses.

Lenticular. — Shaped like a double-convex lens.

Lignified. — Woody; cell walls impregnated with lignin.

Ligulate. — Strap-shaped.

Ligule. — 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.

Locule. — Cell cavity.

Loculicidal. — Refers to capsules which split lengthwise through the middle
of each cell.

Lodicules. — Small scales (inner perianth) surrounding the ovary in grasses.

Lumen. — Cell cavity.

Lyrate. — ^Lyre-shaped; the end lobe of pinnatifid leaf is much larger than
the rest.

Marginal. — Along the edge or margin.
Median. — Middle.
Medulla. — Pith.

Mericarp. — One-half of the fruit of Umbelliferae.
Mesocarp. — Middle layer of pericarp (ovary wall).
Mesocotyl. — Axis between base of coleoptile and grain, in grasses.
Micr'opyle. — The opening between the ovule or seed coats.
Microsporangium. — Anther sac; case bearing microspores.
Monxcious. — 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.

Obcordate. — Heart-shaped, with broad end at the tij).

GLOSSARY 647

Oblate. — Flattened at the ends.

Obovate. — Egg-shaped in outline, with the broader end at the tip.

Obsolete. — Rudimentary, or entirely absent.

Obtuse. — Blunt or rounded at the apex.
• Ocrece. — Sheathing stipules in Polygonaceae.

Orbicular. — 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.

Palet (palea). — Outer perianth segment of grass flower.

Palmate. — ^Leaf segments or leaflets radiate from a point like the fingers
from the palm of the hand.

Panicle. — A compound raceme, as in oats.

Paniculate. — Flowers in panicle or panicle-like inflorescence.

Papilla. — A small protuberance.

Papillose. — With papillae.

Pappus. — Bristle-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.

Petaloid.—'Peta.l-]ike.

Petiole. — The stalk of a leaf.

648 BOTANY OF CROP PLAJSJTS

Plllccm. — 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.

Pinnalifid. — Pinnately cleft to the middle of the blade, or further.

Pistillate. — Bearing pistils only.

Placenta. — The membrane or surface bearing ovules.

P/ica/e.— Plaited.

Plumose. — Plume- or feather-like.

Plumule. — The first bud in the young plant.

Polyadelphous (stamens). — Separate, or in more than two groups.

Polygamo-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.

Ptibescence. — 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 (cauline).

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.

Rejlexed. — Turned back.

Regular (flower). — The parts of each whorl similar.

Reniform. — Kidney-shaped.

Reticulate. — Netted.

Retrorse. — Turned back or downward.

GLOSSARY 649

Rhizome. — Rootstock; underground stem, usually horizontally elongated.
Rotate. — Wheel-shaped.
Ruderal. — Growing in waste places; weed.

Runner. — A prostrate, slender, above-ground stem, such as in the straw-
berry.

Saccate. — With a sac.

Sagittate. — Shaped like an arrow-head, with the lobes turned downward.

Salverform (sympetalous corolla). — Tubular with a spreading limb.

Scabrous. — Rough.

Scale. — Reduced leaf that appears lower on the stem than the foliage leaves.

Scapose. — Bearing a nearly leafless flower stalk arising from the base of
the plant.

Schizocarp. — A dry, indehiscent fruit, of two carpels, each one-seeded,
which split apart at maturity into two halves or mericarps.

Sclerenchymatous.—Compostd 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.

650 BOTANY OF CROP PLANTS

Standard. — The large petal in the flowers of Leguminosae.

Sterile. — Unproductive; without the reproductive elements.

Slipitate. — Provided with a stalk or stipe.

Stipules.- — Appendages at the base of the petiole.

Stipulate. — Bearing stipules.

Stolon.— A trailing stem, above ground, that easily takes root at the nodes
when it touches the ground.

Stooling. — Production of secondary branches from lowermost nodes, as in
grasses; tillering.

Strobile. — Spike-like pistillate inflorescence of hop; also cone-like group of
sporophylls.

Stylar. — Of or pertaining to style.

Stylopodium. — Style-foot. The nectariferous gland at the base of the style
in the Umbelliferous fruit.

Suh. — 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'; .—^'ith. the anthers united, as in Compositas.

Tassel. — Staminate inflorescence in corn.

Tendril. — Slender, coiled organ used in climbing.

Terete. — Cylindrical; pencil-shaped.

Ternate. — Arranged in threes or divided into three divisions.

Testa. — Seed coat.

Tillering. — Production of branches from the lowermost nodes, as in grasses.

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.

Tuberculate. — Furnished with tubercles or small projections.

Tuberous. — Swollen and tuber-like.

Tubular. — Tube-shaped.

Turbinate. — Top-shaped.

GLOSSARY 651

Umbel. — An indeterminate type of inflorescence, in which the pedicels
arise from the same point.
Umbellate. — Umbel-like.
Umbellet. — Umbel of secondary order.
Undulate. — With wavy margin.
Utricle. — A one-seeded fruit with a bladder-like covering.

V abate (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.

Vexillum. — 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.

INDEX

Abutilon, 506
Abyssinian oats, 130
Achene, 58
Achillea, 625
Acrospire, 144
Adjuki bean, 423
Adriatic figs, 275
Aegilops, no
African cotton, 5 1 7

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,

Almond, 410

bitter, 411

hard-shelled, 411

oil, 411

soft-shelled, 411

sweet, 411
Aloe, 229
Alopecurus, 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
238 Antennaria, 625
653

654

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-ursi, 543
Arnica, 625, 628

alpina, 600
Arrhenatherum elatius, 75
Artemisia, 625, 628
Artichoke, globe, 639

Jerusalem, 639
Artificial gums, 185
Artocarpus communis, 252
Arundinaria, 84
Ascomycetes, 64
Asiatic cotton, 511, 512
Asparagus, 244

bean, 422, 458

falcatus, 244

"fern" 246

Asparagus, laricinus, 244

lettuce, 632

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, 131

orientalis, 125, 130, 131

sativa, 89, 125, 126, 128, 130, 131

sterilis, 131

strigosa, 130, 131

wiestii, 131
Awns, 82
Azalea, 543

Bagasse, 227
Baltic alfalfa, 447
Bamboo, 69
Bambusae, 84
Banner, 414

oats, 130
Banyan, 16

tree, 267
Barbe de Capuchin, 636
Bark, 39, 40
Barley, 72, 88, 89, 135

black, 145

655

Barley, blue, 145

fan, 146

four-rowed, 144

hooded, 136, 137, 145, 146

hull-less Jerusalem, 145

hybrid, 145

medium, 137, 143, 145, 146

Nepal, 145

peacock, 146

six-rowed, 144

two-rowed, 145
bent, 147
erect-eared, 147
naked, 146
nodding, 147
Barnyard grass, 219

millet, 210, 219, 220
Basidiomycetes, 64
Basin, 378
Bean, 421

adjuki, 423

asparagus, 422, 458

broad, 422, 426, 429

coffee, 456

Dolichos, 422

Dutch case-knife, 423

flowering, 423

hyacinth, 422

Jack, 422

kidney, 423, 426

Lima, 423, 424

locust, 422

Mexican, 424

mung, 423

painted lady, 423

scarlet runner, 423

Sieva, 423, 424

soja, 456

soy, 422, 455

velvet, 422

Windsor, 427, 429
Beards, 82
Beet, common garden, 300, 310

Beet, foliage, 301
leaf, 301, 312
ornamental, 301
pulp, 309
sea-kale, 312
seed, 306

multiple-germ, 306
single-germ, 306
silver, 312
spinach, 312
sugar, 300, 301
wild, 301

Belladonna, 559

Benincasa cerifera, 613

Bergamot, 487

Beriberi, 206

Berry, 59

Berseem, 433

Beta, 298

cycla, 312
maritima, 301
vulgaris, 300

Bidens, 625

Biennials, 21

Bigarreaus, 403

Bilberry, dwarf, 546
tall bilberry, 547
thin-leaved, 544

Bindweed, 284

Binomial system, 64

Bird's-foot trefoil, 466

Bistort, 286

Bittersweet, 561

Black apricot, 405
barley, 145
bitter vetch, 428
blueberry, 547
-cap raspberry, 357
mulberry, 255, 257
mustard, 327, 339
nightshade, 560
salsify, 635

Blackberry, 354

656

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
British gums, 185
Broad bean, 422, 426, 429
Broccoli, 334
Bromus inermis, 76
Broom corn, 88, 196, 197

-corn millet, 210, 2r3
Brown mustard, 339
Brush, 99

Brussel's sprouts, 329, 330
Bryophytes, 62
Buchloe, 70

dactyloides, 76
Buckbean, 414
Buckwheat, 286, 289

common, 289
gray, 294

family, 284

Japanese, 294

notch-seeded, 294

silver hull, 294

Tatary, 293
Bud variation, 25
Buds, 23

accessory, 24

adventitious, 24

alternate, 25

axillary, 24

branch, 23

classification of, 23

dormant, 23

flower, 23

grafting, 23

lateral, 24

leaf, 23

mixed, 23

opposite, 25

INDEX

657

Buds, terminal, 24

supernumerary, 24
whorled, 25

Buffalo bur, 561
currant, 319

Bulbs, 32, 229

Bullaces, 400

Bulletin Smyrnas,

Bundle scar, 26

Bupleurura, 530

275

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, 17
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

658

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
Chrysothamnus, 625
Ciboule, 237, 239
Cicer arietinum, 467
Cichorium, 628

endiva, 635, 636

intybus, 635, 636
Cider, 383
Cinque-foil, 348
Citrange, 489
Citron, 480, 622, 623
Citrullus, 610, 622

vulgaris, 623
Citrus, 476

aurantifolia, 480, 483

aurantium, 480, 487

bergamia, 487

grandis, 480, 485
ichangensis, 487

Citrus, key to principal species of, 479

limonia, 479, 481

medica, 479, 480

mitis, 487

nobilis, 480, 485
deliciosa, 485
unshiu, 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, 43S

Dutch, 433

hop, 442, 449

giant, 453

Italian, 435

Japan, 465

Ladino, 434

mammoth, 433. 439> 44i

meadow, 441

medium red, 441

Persian, 433

purple, 436

red, 433. 43^

scarlet, 433, 435

Shaftal, 433

spotted bur, 442, 449

Swedish, 433, 434

sweet, 452

toothed bur, 442, 452

white, 433, 441

zigzag, 433, 441
Cloudberry, 350
Club mosses, 62

wheat, III, 112, IT4
Cob, 163
Coffee bean, 456
Coleanthus, 81

INDEX

659

Coleoptile, 104
Coleorhiza, 10, 103
Collard, 329, 330
Collodion, 526
Colocynth, 622
Columnar epithelium, 104
Commissure, 532
Common apple, 379, 381

apricot, 405

barnyard grass, 210

bread wheat, in, 112, 113, 114

buckwheat, 289

eggplant, 586

fig, 269, 275

gray buckwheat, 294

hop, 33

millet, 219

onion, 232, 237

pear, 384, 385

six-rowed barley, 144

sugar beet, 300, 310

sweet pea, 432

wheat, 65, III, 112, 114
Companion cells, 35
Compass plant, 632
Composite family, 625
Compositae, 625

key to important genera of, 628
Concord grape, 501
Conium, 532
Convolvulacese, 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

WUd, 520
Cottonseed hulls, 524

meal, 524

oil, 524
Couloure of Muscat grape, 498
Cowberry, 550
Cowpea, 460
Crab-apple, American, 379

flowering, 379

narrow-leaved, 379

Siberian, 379

Soulard, 379, 381

66o

INDEX

Crab-apple, western, 379, 381
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
Cyperace£e, 85
Cyphomandra betacea, 592
Cypress vine, 554
Cytase, 142
Cytoplasm, 6

Dahlia, 625

Dakota vetch, 429

Damson, 400

Dandelion, 628

Dangleberry, 547

Danish ball head cabbages, 332

INDEX

66i

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, 197

Durum wheat, 89, in, 112, 113
Dutch case-knife bean, 423

clover, 433
Dwarf bilberry, 546

Dwarf broom corn, 200

purple eggplant, 587
Dye-weed, 414

Ear, 162

Early or forcing radishes, 243
Earth apple, 639
Ecballium 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
Epigasa repens, 543
Epiphyte, 28
Episperm, loi
Equisetales, 64
Erect-eared barley, 147
Ericaceae, 543
Erigeron, 625, 628

662

INDEX

Erinocyce figs, 275
Eriogonum, 285, 286
Eryngium, 530
Euchlaena mexicana, 18 r, 182
European black currant, 319, 320

cranberry, 544

gooseberries, 321

raspberry, 357

strawberry, 363, 364
Eurotia, 297

Evergreen or fire thorn, 366
Everlasting pea, 432
Exocarp, 58
"Eyes," 31

Fagopyrum, 286

emarginatum, 294

tataricum, 293

vulgare, 289
False flax, 326

Solomon's seal, 21
Fan barley, 146
Farkleberry, 543
Fennel, 533
Fenugreek, 467
Fermentation, 150
Fern plants, 62
Fertilization, 52
Festuca ovina, 79

pratensis, 76
Fiber flax, 473

of cotton, 514
Ficus, 267

aurea, 267, 268

benghalensis, 267

brevifolia, 268

carica, 268, 269

elastica, 252

religiosa, 267
Field cucumber, 621

pea, 418, 420
Fig, 267

Adriatic, 275

Fig, common, 269, 275

Cordelia, 276

Erinocyce, 275

Golden, 267

Mission, 275

San Pedro, 275

Smyrna, 275

wasp, 271

wild, 276
Filament, 48
Filicales, 64
Finger millet, 210
First patent, 108
Five-finger, 348
Flat Dutch cabbages, 332

onions, 241

-podded pea, 432
Flax, 48, 470

family, 469

fiber, 473

large-seeded, 473

Sicilian, 473

small-seeded, 473
Fleabane, 625, 628
Flint corn, 178, 180
Flour, kinds of, 108
Flower, apetalous, 55

complete, 55

hermaphroditic, 55

incomplete, 55

naked, 55

perfect, 55

pistillate, 55

staminate, 55

symmetry of, 53
Flowering bean, 423

crabapple, 379

raspberry, 254
Flowers, 48

incomplete, 55

parts of representative, 48
Fly oats, 131
Foeniculum, 533

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

californica, 363

chiloensis, 363, 364

glauca, 363

vesca, 363, 364

virginiana, 363
Fraxinus, 551
Fruits, kinds of, 58

dehiscent, 58

dry, 58

fleshy, 59

indehiscent, 50
Fungi, 62
Furrow, 100
Fusarium, 570

Gall flowers, 271
Garden pea, 4181

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, 1 55

meal, 186
Glutenin, 106
Glycyrrhiza, 414
Golden currant, 319
fig, 267

wonder millet, 218, 219
Goldenrod, 625
Goober, 462
Gooseberry family, 316

gourd, 617
Gooseberries, 321
American, 321
European, 321
Goosefoot, 296

family, 296
Goose wheats, 113
Gossypium, 508

barbadense, 519, 520
hirsutum, 517, 518, 520
Gossypol, 524
Gourd, 610, 613
family, 606
gooseberry, 617

664

INDEX

Gourd, winter, 615
Grafting, 36
Graham flour, 108
Grain, 83

coats, 96
Graminea;, 69
Granules, 8
Grape, 492

Catawba, 501

Concord, 501

Delaware, 501

family, 491

Muscat, 498

Niagara, 501

northern fox, 499, 500

Old World, 499

raisin, 499, 501

river bank, 499, 500

sand, 499, 500

southern fox, 499, 500

sugar, 185

summer, 499, 500

wine, 499, 501
Grapefruit, 485
Grass family, 69

awnless brome, 76

bunch, 76

buffalo, 70, 76

quack, 75

rice-cut, 70

tall oat, 75
Grasses, bulbous, 75

rhizome-bearing, 75

stoloniferous, 76

tufted, 76
Greasewood, 297
Green asparagus, 250

foxtail, 211, 219

gages, 398
Green-weed, 414
Grimm alfalfa, 447
Griottes, 404
Groove, 100

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, hemp, 280
Hairs, basal, 92
Hairy vetch, 427, 430
Halophyte, 296
Head, 56

lettuce, 633
Hearts, 403
Heath family, 543
Hedysaras, 415
Helianthus, 628

tuberosus, 639
Hemp, 252, 276

sisal, 281

tow, 280
Hennequin, 281
Hepaticse, 64
Herb, 2

Hesperidium, 478
Heterostyly, 292
Hibiscus, 506

esculentus, 507, 527

syriacus, 508
High -bush blackberry, 354

blueberry, 547, 550
Hog millet, 213
Hollyhock, 508
Homalocenchrus, 70, 81
Homogamy, 169
Honduras rice, 206
Hooded barley, 136, 137, 145, 146
Hop, 2,3, 252

INDEX

66s

Hop, clover, 442, 449
-meal, 264
-tree, 475
Hordeum, 88, 135

distichon, 135, 136, 137, 143, 145
erectum, 147
nudum, 146
nutans, 146, 147
zeocriton, 146
spontaneum, 148
vulgare, 144,
coeleste, 145
coerulescens, 145
hexastichon, 136, 137, 143, 144,

146
intermedium, 137, 143, 145, 146
nigrum, 145
pallidum, 143, 145, 146
trifurcatum, 136, 137, 145, 146
Horse millet, 213

nettle, 560
Horseradish, 345
Horsetails, 62
Hortulana plum, 400
Hosackia, 429
Hubbard squash, 614
Huckleberry, 547
black, 547, sso
blue, 546, S47
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

666

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
Knotweed, 284, 286
Kochia, 297
Koeleria, 79
Kohlrabi, 330, 333
Kowliang, 197
.Kuhnia, 627
Kumquat, 487

Hongkong wild, 489

Marumi, 489

Meiwa, 489

Nagami, 488

oval, 488

round, 489

Lablab, 422
Labrador tea, 543
Lactuca, 628
sativa, 629

angustana, 632

Lactuca, sativa, capitata, 633
intybacea, 633
romana, 633

scariola, 630
Ladino clover, 434
Lagenaria vulgaris, 613
Lamb's quarters, 296
Lamella, middle, 375
Lamina, 77
Large cranberry, 548

leaf tomato, 590

-seeded flax, 473
Lathyrus, 414
Lawn grass, 70
Layering, 316
Leaf, beet, 301, 312

floral, 2

foliage, 2

scale, 2

scar, 26

stalk, 42
Leaflets, 44

Leafy-cluster blackberry, 354
Leaves, 42

compound, 44

development of, 42

foliage, 42

kinds of, 42

parts of, 42

simple, 44

structure of, 44
Leek, 232, 236, 238
Ledum, 543
Legume, 413
Leguminosse, 413

key to principal genera of, 416
Lemma, 80
Lemon, 481

Ichang, 487
Lenticel, 27
Lepidium, 326
Lespedeza striata, 465
Lettuce, 628

INDEX

667

Lettuce, asparagus, 632

cos, 633

cutting or cut-leaved, 633

garden, 629

head or cabbage, 633

key to types of, 632
Leucoplastids, 8
Lianas, 33
Licorice, 414
Lignin, 36

Ligulate flowers, 627
Ligule, 78
Liguliflorae, 627
Ligustrum, 551
Lilac, SSI
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
Low black blueberry, S46
blueberry, 546
bush blueberry, sso
Luffa, 613
Lupines, 465
Lupinus, 46s
Lupulin, 264

glands, 264
LupuHne, 266
Lycium, 559
Lycopersicum, 587

esculenfum, cerasiforme, 587
grandifolium, 587, s88
pimpinellifolium, 587, 588
pyriforme, 587
validum, 587
vulgare, S9o
Lycopodiales, 64

Macaroni, 118

wheats, 113
Macounastrum, 284
Maiz de coyote, 179
Maize, 88, iS7
Male nuclei, so
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
Malvaceae, 50s

key to important genera of, 508
Mamme, 272
Mammoni, 272

668

INDEX

Mammoth clover, 433, 439, 441

pumpkins and squashes, 615
Mandarin orange, 485
Mand's wonder forage plant, 213
Mane oats, 130
Mangels, 313
Mangel- wurzels, 313
Man-of-the-earth, 554
Marblehead squash, 614
Marigold, 625
Marrow squashes, 614
Marsh mallow, 506
Massecuite, 227
Mayberry, 358
Mazzards, 402
Meadow clover, 441
fescue, 76
foxtail, 79
Meadows, 69
Mealiness, in apple, 375
Medicago, 441

arabica, 442, 449

inermis, 451
falcata, 443, 447
hispida, 442, 452
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, 143, 145, 146

red clover, 441
Medulla, 18
Medullary ray, 35, 39
Megarhiza calif ornica, 610
Melilot, 453
Melilotus, 452

Melilotus, alba, 453, 454
altissima, 454
gracilis, 454
indica, 454
officinalis, 453, 454
speciosa, 454
Melon apple, 620

pear, 561
Melons, 618

cucumber, 620
Dudaim, 620
Mango, 620
netted, 618
orange, 620
pineapple, 618
pomegranate, 620
Queen Anne's pocket, 620
snake, 618
winter, 619
Mendelism, 421
Mendel's law, 421
Mericarp, 532
Meristem tissue, 33
Mesembryaceae, 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

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

family, 554
Morus, 252, 253
alba, 255

tartarica, 255
venosa, 255
key^,to principal species of, 255
multicaulis, 256
nervosa, 256
nigra, 255, 257
rubra, 255, 257, 258
Moss plants, 62
Mountain ash, 366
bramble, 351
cranberry, 550
mahogany, 348
sorrel, 284
spinach, 299
timothy, 223
tobacco, 600
Mulberry, 252, 253
black, 25s, 257
family, 252
paper, 254

Mulberry, red, 255, 257, 258
Russian, 255
white, 255
Mule flowers, 271
Multiplier onions, 242
Multipliers, 241
Mung bean, 423
Muscat grape, 498
Musci, 64

Musk cucumber, 620
Muskmelon, 618
Mustard, 327

black, 327, 339

brown, 339

Chinese, 340

family, 323

Indian, 340

Japanese, 340

pot-herb, 340

white, 327, 340
Myrobalan plum, 400
Myxomycetes, 63

Naked oats, 130

wheats, in, 112
Nankin cotton, 517
Nardus, 81
Narbonne vetch, 429
Narrow-leafed crab-apple, 66, 379

leaved vetch, 428
Navel orange, 484
Nectaries, of cotton, 512
Nectarine, 410
Nepal barley, 145
Nepenthes, 47
New Zealand spinach, 299
Niagara grape, 501
Nicotiana, 560, 596

alata, 600

glauca, 596

persica, 600

quadrivalvis, 600

rustica, 600

670

INDEX

Nicotiana, tabacum, 597

tomentosa, 596

wigandioides, 596
Nodding barley, 147
Node, 22
Nodes, 72

Non-saccharine sorghums, 196
Northern dewberry, 65, 356

fox grape, 499, 500
Nucellus, 50, 102
Nucleoli, 6
Nucleus, 6, 8
Nurse crop, 149

Oats, 88, 89, 123
Abyssinian, 130
Algerian, 131
animated, 131
banner, 130

flyj 131

hull-less, 130

mane, 130

Mediterranean, 130

naked, 130

panicle, 130

rough, 131

short, 130

side, 130

single, 126

sterile, 131

Tatarian, 130

twin, 126

wild, 130
Ochrus, 432
Ocrea, 284
Oil cake, 473

meal, 473
Okra, 527

Old World plums, 397
Oleaceae, 551
Olea europooea, 551
Oleomargarine, 524

Olive, SSI

family, ssi
Onion, 231, 240

common, 232, 237

Egyptian, 241, 242

multiplier, 241, 242

perennial tree, 243

potato, 241

top, 241, 242

tree, 241, 242

Welsh, 231, 239
Onions, types of, 241

composition of, 243

uses of, 244
Onobrychis viciaefolia, 465
Ophioglossales, 64
Orache, 299
Orange, blood, 484

Calamondin, 487

common, 484

king, 48s

faiandarin, 485

Mediterranean, 484

navel, 484

Satsuma, 48s
, Seville, 487

sour, 487

Spanish, 484

sweet, 484

trifoliate, 489

Unshiu, 485
Organs, 4

absorptive, 4

reproductive, 4
Ornamental beet, 301
Ornithopus sativus, 465
Oryza, 81, 87, 88

glutinosa, 204

granulata, 206

oflBcinalis, 206

sativa, 200, 206
utilissima, 206
communis, 206

INDEX

671

Oryza, sativa, minuta, 206
Osage orange, 252
Ovary, 48

inferior, 54

superior, 54

wall, loi
Ovules, 48, so
Oxypolis, 530
Oxyria digyna, 284
Oyster plant, 633

Spanish, 635

Pacific Coast dewberry, 352
Painted lady bean, 423
Palea, 80
Palet, 80

Palisade tissue, 44
Panicle, 56, 79

oats, 130
Panicum, 210

miliaceum, 210, 213
compactum, 215
contractum, 215
effusum, 215
Papaveraceae, 326]
Paper mulberry, 252, 254
Pappus, 627

Papyrus papyrifera, 252, 254
Parsley, 539
Parsnip, 536
Parthenocarpy, 374
Parthenocissus, 492
Pastinaca, 533

sativa, 536
Pasture crop, 149
Patent flour, 108
Patanas, 69
Pea, 417

chick, 467

common sweet, 432

edible-podded, 418

family, 413

everlasting, 432

Pea, field, 418, 420

flat-podded, 432

garden, 418

perennial, 432

shelling, 418

sugar, 418

Tangier, 432

wild, 432
Peach, 407
Peacock barley, 146
Peanut, 462

butter, 464

meal, 465

oil, 465
Pear, 384

Chinese, 384, 385

common, 384, 385

Japanese, 384, 385

sand, 384, 385

tomato, 587
Pearl barley, 149

miUet, 211
Peepul tree, 267
Pencilaria, 213
Pennisetum, 88, 210

spicatum, an
Penny cress, 326
Pepino, 561
Pepo, 608
Pepper, 592

Cayenne, 595

Tabasco, 595

vine, 492
Perennial, 20, 70

pea, 432

tree onions, 243
Perianth, 49
Periblem, 17
Pericarp, loi
Pericycle, 17
Peridrigon plums, 399
Perisperm, 102
Perpetual strawberry, 363, 364

672

Persian clover, 433

tobacco, 600
Persicaria, 286
Peruvian alfalfa, 447
Petals, 48
Petiole, 42
Petunia, 559
Phaeophycese, 63
Phaseolus, 421

angularis, 423

aureus, 423

key to principal species of, 423

lunatus, 423, 424
macrocarpus, 424

multiflorus, 423

vulgaris, 423, 426
nanus, 426
Phleum, 222

alpinum, 223

pratense, 222
Phloem, 18, 35

elements, functions of, 36

parenchyma, 35
Photosynthesis, 46
Phycomycetes, 64
Phylloxera, 499
Phylogeny, 83
Physalis, 559
Pickles, 621
Pie plant, 286
Pileole, 104
Pistil, 48, 51

Pistillate inflorescence, 55
Pisum, 416, 417

sativum, 418
Pitcher plants, 47
Pitching, 150
Pith, 18, 39
Placenta, 50
Placentation, 53
Plant body, i

fundamental internal structure of, 4

cell, 4

Plant body, cell, discovery of, 4
structure of, 6

nomenclature, 64
Plastids, chloroplastids, 8

chromoplastids, 8

leucoplastids, 8
Plerome, 17
Plum, American, 397, 400, 401

Chicasaw, 401

family, 391

hortulana, 400

Japanese, 400

key to principal species of, 397

myrobalan, 400

old world, 397

tomato, 590
Plumy asparagus, 246
Poa pratensis, 70
Poaceae, 69
Pod, 58

corn, 178, 180
Polar nuclei, 50
Polish wheat, in, 112, 113
Pollen grains, 48, 52

mother cells, 50

tube, 52
Pollination, 51
Polygonaceae, 284

key to principal genera, 286
Polygonum, 284
Pomaceae, 366

key to important genera of, 367
Pome, 366
Pomelo, 485
Poncirus, 476, 489

trifoliata, 489
Pop corn, 178, 180
Poppy family, 326
Pot-herb mustard, 340
Potamogeton, 29
Potato, 561

family, 559

onions, 241

673

Potentilla, 348
Poulard wheat, iii, 112
Prickly ash, 475

cucumber, 617
Privet, SSI
Profichi, 272
Prophyllum, 80
Prop roots, 16, 159
Proso, 213

millet, 210
Protandry, 170
Protease, 142
Proteose, 105
Protogyny, 170
Protoplasm, 9
Protoplasmic membrane, 6
Protoplast, 6
Prunes, 398
Prunus, 394

americana, 400

amygdalus, 410

angustifolia, 401

armeniaca, 405

avium, 402

besseyi, 404

cerasifera, 400

cerasus, 402, 403

cuneata, 404

dasycarpa, 407

domestica, 398

emarginata, 404

hortulana, 400

insititia, 399

key to main groups of, 394

mahaleb, 404

mume, 407

munsoniana, 401

nigra, 401

pennsylvanica, 404

persica, 407

pumila, 404

sibirica, 407

triflora, 400
43

Psedera tricuspidata, 33
Pseudomonas radicicola, 413
Psilotales, 64
Ptelea, 475
Pteridophytes, 62
Pumpkin, 613

field, 613

mammoth, 613

Valparaiso, 613 '
Purple apricot, 407

cane raspberry, 337

clover, 436

vetch, 428
Pyrus, 384

communis, 384, 385

serotina culta, 384, 385

Quackgrass, 21, 70
Quamoclit quamoclit, 554
Quince, 388

Rabbit-brush, 625
Raceme, 56, 78
Rachilla, 79
Rachis, 79, 92
Radicula, 344

armoracia, 345

nasturtium-aquaticum, 345
Radicle, 57
Radish, 341

garden, 341

rat-tailed, 343

wild, 342
Ragi millet, 210
Raisin grape, 499, 500
Raisins, 501
Raphanus, 341

caudatus, 343

raphanistrum, 342

sativus, 341
Raspberry, 357

American red, 357

black cap, 357

674

INDEX

Raspberry, European red, 357

key to principal species of, 357

purple-cane, 357
Rat-tailed radish, 343
Ray flowers, 627
Receptacle, 49
Red cabbages, 332

clover, 433, 435

currant, 320

mulberry, 255, 257, 258

Peruvian cotton, 517
Repeated germination, 109
Reproductive activity, i
Retting, 279
Rheum, 289

palmatum, 289

undulatum, 289
Rhizoctonia, 569
Rhizomes, 29, 75
Rhododendron, 543
Rhodophyceae, 63
Rhubarb, 286
Ribes, americanum, 319, 320

aureum, 319, 320

grossularia, 319, 321

key to important species of, 319

nigrum, 319, 320

oxycanthoides, 319, 321

rubrum, 319, 320

vulgare, 319, 320
Rice, 88, 202

Canada, 206

cultivated, 206

large-kerneled, 206

small-kerneled, 206

wild, 206, 207
River bank grape, 499, 500
Robinia, 414
Rockmelons, 6i8
Root cap, 17

crown, 157

hair, effect of external factors upon
development of, 20

Root cap, structure of, 20
-hair zone, 19
primary, 10
sheath, 10, 103

system, effect of environment upon
character of, 14
primary, 91
temporary, 91
systems, 2, 10
adventitious, 11
development of, 10
fibrous, 10, II
primary, 10
tap, 14

temporary, 10
tubercles, 413
Roots adventitious, 11
air, 16
classification of, based upon their

medium of growth, 16
general characteristics of, 15
length of life of, 21
seminal, 10
soil, 16

structure of, 16
tap, 14
water, 16
work of, 14
Rootstocks, 29, 75
Rosaceas, 348

key to important genera of, 350
Rose family, 348

of Sharon, 508
Rough oats, 131
Rubus, 350, 353

argutus, 354, 355
bernardinus, 357
chamaemorus, 350
cuneifolius, 354, 355
glaucifolius, 357
idaeus, 357
invisus, 356
key to groups of, 353 •

INDEX

67s

Rubus, leucodermis, 357

microphyllus, 358

neglectus, 358

nigrobaccus, 354
albinus, 354
sativus, 354

occidentalis, 357

strigosus, 357, 358

trivialis, 356

villosus, 354, 356
roribaccus, 356

vitifolius, 352, 356, 358
Rue family, 475
Rumex, 284
Runner, 13, 32, 76, 358
Rushes, 8s
Russian mulberry, 255

thistle, 47, 296

vetch, 430
Rutabaga, 337
Rutaceae, 475

kej' to important genera of, 476
Rye, 88, 89, 153

Saccharum of&cinarum, 225

Sachs, 177

Sage, 625, 628

Sainfoin, 465

Sake, 207

Salicornia, 297

Salsify, 628

black, 63s

Spanish, 635

yellow-flowered, 635
Salsola, 296
Saltbush, 296
Salt-grass, 55
Salt wort, 47
Samara, 551
Sand bur, 560

blackberry, 354

grape, 499, 500

pear, 384, 385

San Pedro figs, 275
Sanicula, 532
Sarcobatus, 297
Sarracenia, 47
Sauerkraut, 332
Satsuma orange, 485
Savannahs, 69
Savoy cabbages, 332
Scales, 78
Scallop, 613
Scarlet clover, 433, 435

runner bean, 423

strawberry, 363

vetch, 428
Schizomycetes, 63
Schizophytes, 63
Schuster, 84
Scientific name, 64

versus common name, 66

names, descriptive nature of, 66
Scion, 36

Scorzonera hispanica, 635
Scouring rushes, 62
Scutching, hemp, 280
Scutellum, 104
Sea Island cotton, 520, 521
Sca-kale beet, 312
Secale, 88, 153

anatolicum, 155

cereale, 89, 153

montanum, 155
Second patent, 108
Secondary cortex, 38
Sedges, 85
Seed ball, 306

coats, 57

germination of, 59

leaves, 59

plant body, size and form of, 2
principal parts of, i
Seeds, 57
Seedlings, 57
Self -fertility, 372

676

INDEX

Self-sterility, 372, 497
Seminal roots, 103
Semolina, 118
Sepals, 48
Sequoias, Giant, 2
Serradella, 465
Service berry, 366
Setaria, 210
Seville orange, 487
Shaddock, 485
Shaftal clover, 433
Shallot, 237, 238
Shallu, 196, 197
Shank, 163
Shantz, 117
Sheath, 77
Sheep's fescue, 79
Shelling pea, 418
Shepherd's purse, 326
Shoot system, 2

development of, 22
Short oats, 130
Shrub, 2
Siberian apricot, 407

crabapple, 379

millet, 218, 219

vetch, 430
Sicilian flax, 473
Sickle alfalfa, 447
Sicyos angulatus, 606
Sicyosperma gracilis, 610
Sieva bean, 423, 424
Sieve tubes, 35
Sikkim cucumber, 621
Silage, 186
Silicle, 325
Silique, 325
Silks, 171
Silo, 186
Silver beet, 312

hull buckwheat, 294
Single oats, 126
Sisal hemp, 281

Sitopyros, no
Six-rowed barley, 144
Small cranberry, 548, 549
Small-seeded flax, 473
Smilax, 244
Smith, 175
Smother crop, 149
Smyrna figs, 273, 275
Snake cucumber, 620

eggplant, 587
Soap weed, 229
Soft corn, 178, 180
Soja bean, 456
Solanacese, 559,

key to important genera of, 560
Solanum, 560

carolinense, 560, 561

chiloense, 561

commersonii, 561

dulcamara, 560, 561

elaeagnifolium, 560

immite, 561

jamesii, 561

key to important species of, 561

maglia, 561

melongena, 561
depressum, 587
esculentinum, 586
serpentinum, 587

muricatum, 561

nigrum, 560, 561

rostratum, 560, 561

triflorum, 561

tuberosum, 560, 561, 562
Solidago, 625
Sonchus, 625
Sophia, 326
Sophora, 415
Sorbus, 366
Sorghum, 88
Sorghums, 191

key to principal types, 197

origin of, 197

INDEX

677

Sorghums, uses of, 199
Sorgo, 196, 197
Soulard crabapple, 379, 381
Sour orange, 487
Southern dewberry, 356

fox grape, 499, 500
Sow-thistle, 625
Soy bean, 456
Soya, 455

max, 456
Spanish bayonet, 229

moss, 28

needles, 625

orange, 484

salsify, 635
Spathe, 234
Spelt, 89, III, 112, 113

wheats, iii
Sperm nuclei, 50
Spermatophytes, 62
Sphenophyllales, 64
Spike 56, 79
Spikelet, 78, 79, 80
Spinacea, 298

oleracea, 298
Spinach beet, 312

common garden, 300

key to groups of, 300

mountain, 299

New Zealand, 299
Spines, 33
Spiraea, 348

Spongy parenchyma, 44
Spotted bur clover, 442, 449
Spreading oats, 130
Spur, 23
Spurs, 367
Squash, 610

Canada crookneck, 610, 612

Hubbard, 612, 614

mammoth whale, 615

marblehead, 610, 612, 614

marrow, 614

Squash, summer, 613

turban, 610, 612, 614

Valparaiso, 615
Squirting cucumber, 606
Stages, ripening, 97
Stamens, 48

Staminate inflorescence, 55
Standard, 414

broom corn, 200

patent, 108
Star cucumber, 606, 620
Starches, 177
Starchy endosperm, 103

sweet corn, 178, 180
Strawberry tomato, 592 .
Stele, 17

Stem, of dicot, 33
Stems, 22

aerial, 2

classification of, based upon their
medium of growth, 28

general characteristics of, 26

structure of, 33

underground, 2

work of, 41
Steppes, 69
Stewart, 167
Stigma, 48
Stipules, 42
Stock, 36
Stolon, 32
Stomata, 45
Stone crop, 47
Stooling, 22, 73
Straight bread flour, 108
Strawberry blite, 296

Chilean, 363, 364

European, 363, 364

everlasting, 364

perpetual, 363, 364

scarlet, 363

Virginian, 363

wood, 364

678

Streamside grape, 66
Streptochaeta, 81, 84
Sturtevant, 159, 167, 178
Stylar canal, 168
Style, 48
Stylopodium, 531
Succory, 635, 636
Suckers, 160
Sugar beet, 300, 301
Sugar cane, 225

pea, 418
Sultanas, 501
Summer figs, 275

grape, 499, 500

radishes, 243

wood, 40
Sundew, 47
Sunflower, 625, 628
Swedes, 337

Swedish clover, 433, 434
Sweet clover, 452
white, 454
yellow, 454

corn, 178, 180

orange, 484

pea, leaf, 43

potato, 555

sorghums, 196
Swiss chard, 312
Synconium, 268
Synergids, 50
Systema Naturae, 61
Systematic botany, 60
Syringa, 551

Tabasco pepper, 595
Tall bilberry, 547
Tangelo, 485
Tangerine, 485
Tangier pea, 432
Tangleberry, 547 ]
Tansy mustard, 326
Tap root system, 13

Taraxacum, 628

Tares, 429

Tassel, 55, 162

Tatarian oats, 130

Tatary buckwheat, 293

Teas' weeping mulberry, 256

Tempering, 107

Tendrils, 33

Teneriffe, 243

Teosinte, 166,. 181, 182

Testa, loi

Tetragonia expansa, 299

Thallophytes, 62

Thallus, I

plants, 62
Thermopsis, 414
Thin-leaved bilberrj^ 544
Thistle, 625, 628

family, 625
Thlaspi, 326
Thorn apple, 366, 367
Tillandsia usneoides, 28
Tillering, 22, 73, 74
Timothy, 75, 222
Tissue, 4
Tobacco, 596

Australian, 600

Indian, 600

mountain, 600

Persian, 600

"wild," 600
Tomato, 587

cherry, 587, 590

currant, 587

garden, 590

husk, 592

key to types of cultivated, 59 1

large leaf, 590

pear or plum, 587, 590

strawberry, 592

tree, 592

upright, 587, 590
Toothed bur clover,' 442, 452

INDEX

679

Topinambour, 639
Top onions, 241, 242
Torch-wood, 475
Torus, 49

Toxylon pomiferum, 252
Tracheal tubes, 36
Tracheids, 36
Tragopogon, 628

porrifolius, 633

pratensis, 635
Trailing arbutus, 543
Transpiration stream, 47
Tree, 2

onions, 241, 242

tomato, 592
Trifoliate orange, 489
Trifolium, 66, 432

alexandrinum, 433

hybridum, 433, 434

incarnatum, 433, 435

key to principal species of, 433

medium, 433, 441

pratense, 433, 436
perenne, 439

repens, 433

suaveolens, 433
Trigonella foenum-grcecum, 467
Tripping, of alfalfa flowers, 444
Triticum, 88, 91

cegilopoides, 112, 116

aestivum, in, 112, 114, 116

boeoticum, 112

capitatum, n6

compactum, in, 112, 114, 116

dicoccum, in, 112, 113, 116
dicoccoides, 114, 115, 116

durum, in, 112, 113, 116

hermonis, 114

monococcum, no, in, 112

ovata, no

polonicum, in, 112, 113, 116

spella, III, 112, 113, 116

thaoudar, 112

Triticum, turgidum, in, 113, 116

Tube nucleus, 50

Tuberization, fungus theory of, 569

Tubers, 30, 31

Tubuliflorse, 627

Tulip, 229

Turban squash, 614

Turkestan alfalfa, 447

Turnip, 65, 335

common, 335

Swede, 337
Turnip-rooted celery, 540
Twin oats, 126
Two-rowed barley, 145

Umbel, 56, 234, 530
Umbelliferae, 530

key to genera of economic impor-
tance, 533
Unshiu orange, 485
Upland cotton, 510, 520
Upright tomato, 587, 590
Utricle, 297

Vaccinium, 543, 545

angustifolium, 546, 550

arboreum, 543

atrococcum, 547, 550

caespitosum, 546

canadense, 66, 546, 550

corymbosum, 547, 550

key to chief fruit-bearing species of,
546

macrocarpon, 546, 548

membranaceum, 544

myrtillus, 546

nigrum, 546, 550

ovalifolium, 547

oxycoccus, 546, 549

'vacillans, 546, 550

virgatum, 544

vitis-idaea, 546, 550
Vacciniaceae, 543

68o

Vacuole, 7

Variegated alfalfa, 447
Vascular bundles, 35

elements, 35
Vegetative activity, i
Velvet bean, 422
Vetch, 414, 426

black bitter, 428

crown, 429

Dakota, 429

hairy, 427, 430

Hungarian, 430

kidney, 429

Narbonne, 429

narrow-leaved, 428

purple, 428

Russian, 430

scarlet, 428

Siberian, 430

villous, 430

woolly-podded, 429
Vetchling, 432
Vexillum, 414
Vicia, 414, 426

angustifolia, 428

atropurpurea, 428

dasycarpa, 429

ervilia, 428

faba, 427, 429

fulgens, 429

key to important species of, 427

narbonnensis,, 429

sativa, 427, 429'

villosa, 427, 430
Vigna, 458

catjang, 458

sequipedalis, 458

sinensis, 458, 460
Villous vetch, 430
Vilmorin sugar beet, 308
Vine peach, 620
Vinegar, 383, 503
Virginia creeper, 16, 33

Virginian strawberry, 363
Vitaceae, 491

key to important genera of, 492
Vitis, 492

aestivalis, 499, 500

bourguiniana, 501

labrusca, 499, 500

riparia, 499, 500

rotundifolia, 499, 500

rupestris, 499, 500

vinifera, 499

Wakefield cabbages, 332
Washingtonia, 532
Water cress, 345

hyacinth, 16

lily, 29
Watermelon, 610, 622, 623

types and varieties, 623
Welsh onion, 232, 237, 239
West Indian gherkin, 617
Western crabapple, 379, 381

dewberry, 356
Wheat, 88, 89, 91

classification of the types of, no

club. III, 112, 113, 114

common bread, in, 112, 113, 114

durum, 89, in, 112, 113

grain, microscopic section, 100

hard, 106

naked, in, 112

Polish, III, 112, 113

Poulard, in, 112, 113

soft, 106

spelt, in, 112, 113
White blackberry, 354

clover, 433, 441

currant, 320

mulberry, 255

mustard, 327, 340
Whortleberry, 546
Wild barnyard grass, 210

beet, 301

INDEX

68l

Wild cabbage, 328

cotton, 520

cucumber, 606

emmer, 114, 115

fig, 276

goose wheats, 113

oats, 130

pea, 432

radish, 342

rice, 207

tobacco, 600
Windberry, 550
Windsor bean, 427, 429
Wine grape, 499, 500
Wines, 502
Wings, 415

Winningstadt cabbages, 332
Winter gourd, 615

radishes, 243
Wolberry, 550
Wood, 30

elements, functions of, 37

fibers, 36

parenchyma, 36

strawberry, 364
Woolly-podded vetch, 429
Wormwood, 625, 628

Xanthoxylum, 475
Xenogamy, 52, 95

Xylera, 18, 36

Yams, SS6
Yarrow, 625
Yellow egg plums, 399
-flowered alfalfa, 447
salsify, 635
Young dicot stem, 33
Yucca, 229

Zanta currants, 501
Zea, 87, 157
canina, 179
mays, 158, 178

amylacea, 178, 180

amylea-saccharata, 178, 180

curagua, 179

everta, 178, 180

hirta, 179

indentata, 178, 180

indurata, 178, 180

japonica, 179

key to "species groups" of, 180

saccharata, 178, 180

tunicata, 178, 180, 182
ramosa, 179
Zigzag clover, 433, 441
Zizania aquatica, 206

miliacea, 207
Zygote, 52

C^Onc^ - 9 c>

This book is a preservation facsimile.

It is made in compliance with copyright law

and produced on acid-free archival

60# book weight paper

which meets the requirements of

ANSI/NISO Z39.48-1992 (permanence of paper)

Preservation facsimile printing and binding

Acme Bookbinding

Charlestown, Massachusetts

2006

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