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THE
BOTANY OF CROP PLANTS

ROBBINS

THE
BOTANY OF CROP PLANTS

A TEXT
AND REFERENCE BOOK

BY
WILFRED W. ROBBINS, Pu. D.

PROFESSOR OF BOTANY, COLORADO AGRICULTURAL COLLEGE

ILLUSTRATED

PHILADELPHIA

P.: BLAKISTON’S SON. & CO.

1012 WALNUT STREET
hea’

CopyRIGHT, 1917, By P. BiaxisTon’s Son & Co.

GE foo 3¢

THE MAPLE PRESS YORK PA

PREFACE

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

It has seemed advisable to include chapters (Part I) which
may be needed in some instances to refresh the student’s
knowledge of certain fundamentals, or prepare him for that
which follows in Part II. But in many schools Part II will
be preceded by a general course which-aims to give the stu-
dent a survey of the plant kingdom and an acquaintance with
the large outstanding facts and principles of botany, and in
this case Part I will be omitted. The subject matter of
Part IT is sufficient for a course of one-half year involving
one recitation and two laboratory (5) periods per week.

In the preparation of the book, the writer has had in
mind non-agricultural as well as agricultural schools, for it
cannot escape notice that there is a growing tendency,
wherever botany is taught, to tie it up more closely with
economic interests and to draw more and more upon economic
plants in citing examples and in choosing objects of study in
the laboratory.

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 codperation 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. RoBsins.

CoLorADO AGRICULTURAL COLLEGE.

CONTENTS

PART I

CHAPTER I.—TuE SEED Piant Bopy.
Principal Parts of the Seed Plant Body—Size and Form of the
Seed Plant: Bodysic: ton a2a3 ses ves tees cleo eae he

1-3

CHAPTER JI.—FuNDAMENTAL INTERNAL STRUCTURE OF PLANT Bopy.

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 Plgnt Cell—The Cell Wall—Plastids—Nucleus—
ProtoplasMiewi 2 consis cp paguieewe tage sume ehe mineledelen aaa
CHAPTER III.—Roots.
Development of Root Systems—The Work of Roots—Effect
of Environment upon Character of Root System—General
Characteristics of Roots—Classification of Roots Based upon
Their Medium of Growth—Structure of Roots—Root Hairs,
the Absorbing Organs of a Plant—Root-hair Zone—Structure
of a Root Hair—Effect of External Factors upon Develop-
ment of Root Hairs—Length of Life of Roots..............
CHAPTER IV.—SteEms.
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..........
CHAPTER V.—LEAvEs.
Development of Leaves—Parts of Leaf—Kinds of Leaves—
Structure of Leaves—The Work of Foliage Leaves.........
CHAPTER VI.—FLowers.
Parts of Representative Flower—Development of the Flower
—Stamens—Mature Pollen Grain—Pistil—Ovule—Pollina-
tion—Fertilization—Placentation—Symmetry of Flower—
Relative Positions of Flower Parts—Union of Flower Parts—
Incomplete Flowers—Inflorescence................. 020 eee
CHAPTER VII.—Fruits, SEED, AND SEEDLINGS.
Development of the Seed—Development of the Fruit—Fruit
and Seed Distinguished—Kinds of Fruits—Germination of
the: Seeds scxcsuneciyaeroie detec marries ad acacia cltaacy alauene mielees =

4-9

Io-21

22-41

42-47

48-56

vili CONTENTS

CHAPTER VIII.—TuE CrassIFICATION 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: ReferenceSies unas ens ME epee aha eid ORE ees 60-67

PART ITI

CHAPTER IX.—GraMINEz (Poacre#) 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 ......... 00.0... eee ee 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................. QI-121
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
—aAvena fatua (‘“‘wild oats” )—Origin of Oats—Environmental
Relations—Uses of Oats—The Production of Oats —
REPEPEN CES ies cniisi nt nen arene d ane wipunananenoa meats ata 122-134
CHAPTER XII.—Horpvevm (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) sss ccv ee acwnithew Ses edo keweee ghee ae woe 135-152

CONTENTS ix

(a XIII.—SECALE CEREALE (RYE).
Habit of Plant, Roots—Stems, Leaves—Inflorescence—Spike-
let—Opening of Flower, Pollination and Fertilization—Matur-
ing of Grain, and Mature Grain—Germination of Rye—
Classification, and Origin of Rye—Environmental Relations
—Uses of Rye—Production of Rye—References........... 153-150
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.—Anpropocon SorGHuUM (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—
REICKENCES: Accu yeaer ws ares hone eee Simeon SERN ees EAE De 202-209
CHAPTER XVII.—MILter.
Key to Principal Economic Types (Species) of Millet and
Some Closely Related Common Weed Grasses.............. 210-211
“Pennisetum glaucum (Pearl Millet)—Stem—Leaf—lInflores-
cence—Spikelet and Flower—Pollination—Mature Grain—
Varieties —Oni git s:ceci essa d os cena een oh Sara TaD Aeon 211-213
Panicum miliaceum (Proso, Hog or Broom-corn Millet)—
Stem—Leaf—Inflorescence—Spikelet ‘and Flower—Pollina-
tion—Mature Grain—Varieties—Origin.................... 213-216
Cheztochloa 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 (Chetochloa italica)—Origin of Foxtail Millet. 216-219

x CONTENTS

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

Flowers, and Fruit—Distribution....................0055 219-220
Echinochloa frumentacea (Japanese Barnyard Millet)....... 219-220
Environmental Relations—Uses of Millets—References...... 220-221

CHAPTER XVIII.—Puievum PRATENSE (TIMOTHY).
Description—Environmental Relations—Closely Related Spe-
GLES—REFETEN CES? vested enteeat ee io vatue whe Pa eee TSE RS 222-224

CHAPTER XIX.—SaccHaRUM OFFICINARUM (SUGAR CANE).

Habit, Roots—Stems—Leaves—Inflorescence, Flowers, Fruit
—Geographical—Sugar from Sugar Cane—Production of Cane
SUBAaP scoctecca aes a4 Meee es eRe ee Lee WR eas Raed 8 225-228
CHAPTER XX.—Litiace# (Lity Famity).
Habit, Roots—Leaves—Inflorescence and Biovers—Faiit and
SOCUS i acisiein thd wertnnetoreectdntmsn i eae aatuetn Ba a anauatdeanenesat canna ieaiar 229-230
Allium—Roots—Stems—Leaf—lInflorescence—Flower—Polli-
nation—Fruit—Germination of Seed, and the Seedling—
Geographical—Key to the Principal Cultivated Species of

Genus: Allium (5:05 saeco ect cages eas Fewest ee eee eS 231-237
Allium sativum (Garlic)............... 0000s ee eee eee eee 237
Allium porrum (Leek)..........00... 0. e eee e nents 238
Allium schoenoprasum (Chives or Cives).................55 238
Allium ascalonicum (Shallot)............ 0... ce eee eee eee 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—

TWISES OF ONIONS ccd si-d wceicinsecenntehtonaneuee tudadaa (so tuaaaiest £ 240-244
Asparagus—Generic Description—Economic Importance of
Genuibies surance ce Mediates en ares ban 4 weeds abo 244-246

Asparagus officinalis (Asparagus)—Roots—Stems—Leaf—
Flower—Pollination—Fruit—Geographical—Types and Va-

rieties—References.........0.. 0. cece eect e eee neee 246-251
CHAPTER XXI.—Moracez (MULBERRY Famity).
Description—Key to Principal Genera...................45 252-253

Morus (Mulberry)—Habit, Stems—Leaves—Inflorescences—
Fruit—Other “Mulberries’’—Geographical—Key to Principal
Species of Genus Morus..........., 0... e seen eee eee 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........0 0c ccc cece cece eter nett eee eees 257-258

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

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..............+ 2000 258-267
Ficus (Fig)—Habit, Roots, .Stems—Leaves—Inflorescence—
Geographical Distribution, and Economic Importance...... 267-269

Ficus carica (Common Fig)—Habit of Plant, and Stem—
Leaves—Inflorescence, and Flowers—Pollination—Crops of
Fruit in Caprifigs—Caprification—The Mature Fruit—Geo-
graphical—Types of Figs—Uses of Figs..............2000 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 si. nvcsaacuniaance dag eal wemca st us dee ew 276-283
CHAPTER XXII.—Potyconacrez (BUCKWHEAT FamILy).
Stems—Inflorescences—Flowers—Fruit—Key to Principal
GE MEEAD hoos sevice sunt cantar nduscaacenss oso ak Mio Bilseensne Gud anenr a ren Ue ae 284-286
Rheum rhaponticum (Rhubarb, Pie Plant)—Roots, Stems,
Leaves, Flowers— Fruit — Geographical, and Varieties —
NSE ec, Sein acoactaia te ayspstatt doce epartdn treet site ihe Seean 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............ 000. c cece eee eee 289-205
CHAPTER XXIII.—CweEnopopiacez (GoosEFooTt FAmILy).
Habit, Stems, Leaves—Inflorescence and Flowers—Fruit—
Key to Principal Genera............ 00.0. e eee eee eens 296-298
Spinacia oleracea (Spinach)—Description—Other Plants
Named ‘“‘Spinach”—Groups of True Spinach—Key to Groups
OE SPINACH s.ec rats che teenies Sahai aber Sermeee IAA Br uccrabenshs 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.,.............00.0005 310-312
Chatdi sn s steateins ges eo eetes ous Gees pean eee ea he 312-313

Mangel-wurzels or Mangels—Types—Composition and
UWsOS—RETETENCES a seicscsere 3 clerk Stseace Seek Pound Gone Slaanind Rind ES 313-315

xii

CONTENTS

CHAPTER XXIV.—GrossuLaRIACEZ (GOOSEBERRY FaMILy).

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

Species of Genus Ribes ..............0.00.000000 00 cc eee eeee 316-319
Currants—Species—Uses. . 2.00... 00 0. ccc eee eee ee 320-321
Gooseberries—Species—Uses ...:........000000000 2000 eee 321-322

CHAPTER XXV.—CruciFERz (Mustarp FamIty).

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.............. 0002: e cece eens 330
Brassica oleracea var. gemmifera (Brussels Sprouts)—Types
USCS sane die sh dumrnngaarn cack tesa seine ok Ae Noted mee eC RI i ast Soe eos 330-331
Brassica oleracea var. capitata (Common Head Cabbage)—
Types—Key to Types of Head Cabbage—Uses............ 331-333
Brassica oleracea var. caulo-rapa (Kohlrabi or Turnip-rooted
Cabbage)...........- Bea oat Sbes sales hoe aki beseey Aiken eieaghaatid BR 333
Brassica oleracea var. botrytis (Cauliflower, Broccoli)...... 334-335
Brassica rapa (Turnip)—Description—Geographical—Types

of Turnips—Structure and Uses...............0. 00. esse eee 335-337
Brassica campestris (Rutabaga or Swede Turnip)—Descrip-
HON — USES views eiwe si Weninhe heehee os ceed n ey eae 337-338

Brassica napus (Rape)—Description—Varieties and Uses. . . 338-339
Brassica nigra (Black or Brown Mustard)—Description—
Related Species—Uses........ 0.00 cece eee eee eee eeeees 339-340
Brassica alba (White Mustard).....................0.-004 340-341
Raphanus sativus (Garden Radish)—Habit—Root—Stem—
Leaves—Inflorescence and Flowers—Fruit—Seeds and Seed-
ling—Geographical Distribution and Origin—Closely Related

Species—Types of Radishes.................00. seco ees 341-344
Radicula (Water Cress and Horse-radish)..................- 344-345
Radicula armoracia (Horse-radish)—Description—Geograph-
ical=—Usesicns siawantg cents ie Sa eaeaink coms cumdsearee AES 345
Radicula nasturtium-aquaticum (Water Cress)}—Description
—Geographical—References.............0000cc cece cee eues 345-347

CHAPTER XXVI.—Rosacez& (RosE Famity).

Leaves—Inflorescence—Flowers—Fruit—Key to Important.
Geénera:of Rosace ®iiyeeccipiwis aeccencca geese gin ees 348-350
Rubus (Raspberry, Blackberry, Dewberry) — Stems —
Propagation—Leaves—Inflorescence—Flowers—Pollination—

CONTENTS xill

Fruit—Geographical—Classification—Key to Groups of Genus
Rubusicnete kM eck ac uaeiede s org heed ye tat ee Bae hae ees es elng 350-354
Blackberries—Key to Species of Blackberries—Rubus nigro-
baccus—Rubus nigrobaccus X R. villosus—Rubus argutus—
Rubus cuneifoliusy.... .cseciccc ces nud eae eden nea s 3547-355
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 idzus—Rubus strigosus—Rubus stri-
gosus X R. occidentalis—The Loganberry—Mayberry...... 355-358
Fragaria (Strawberry)—Roots and Stems—Leaves—Inflores-
cence and Flowers—Fertilization, and Development of the
Fruit—The Mature Fruit—Geographical—Principal Fruit-
bearing Species—Key to Principal Species of Fragaria—
Fragaria virginiana—Fragaria vesca—Fragaria chiloensis—
Varieties—Origin of New Varieties—Uses—References...... 358-365
CHAPTER XXVII.—Pomace# (APPLE FaMmILy).
Habit, Leaves—Inflorescence—Flowers—Fruit—Geographical
—Key to Important Genera of Pomacez.................. 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 i the: United, States... sense sceca tesa ean ewe’ 367-384
PHTUSs (POAT) irae oa Be AOL Aran td peice sophia, Sieieeone 384
Pyrus communis (Common Pear)—Stem—Leaves and
Flowers—Fruit—Geographical................ 0.00 cece 385
Pyrus serotina culta (Sand, Japanese, or Chinese Pear)—Self
-sterility in Pears—Dwarf Pears............. 0.0.00 0.cee eee 385-387

Cydonia (Quince)—Cydonia oblonga (Common Quince)—
Stem—Leaves— Flowers — Fruit — Varieties — Uses — Refer-

TICES i nlaeiitn nei aR Gh Ot ate AONE A AOS aastla dead tet -Rtetisiary wecan 387-390
CHAPTER XXVIII.—Drupacez (PLum Famity).

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

Prunus—Key to Main Groups of Genus Prunus............ 394

Plums—Stems—Lea ves—Inflorescence—Flowers—Fertiliza-
tion—Fruit—Classification of Plums—Key to Principal
Speciesiot PlUMSycisjscsocigaieagedtncaaweawu waedig aera nes 394-3907
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............0000. cee e eee eee 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............. 000000005 405-407
Peaches—Stems—Leaves—lInflorescence and Flowers—Fruit
—Geographical—Types of Peaches—Uses, and Production of

Peaches in the United States................... 000220005 407-410
Almonds—Description—Types of Almonds—Uses—Almond
Oil-—Referencéss. 5.5. 623s. edhceare Soa ve SRY PS 410-412

CHAPTER XXIX.—Lecuminos& (PEA FamIty).

Root Tubercles—Habit—Leaves —Inflorescence—Flowers—
Fruit—Seeds—Key to Principal Genera of Leguminos2....413-417
Pisum (Pea)—Description—Types of Peas—Peas and Men-

Gelism—Usess ss 22. ae cay een vase een patie hagas across 417-421
Phaseolus (Bean)—Description—Geographical, and Species—
Key to Principal Species of Phaseolus....... ..........05- 421-424

Phaseolus lunatus (Sieva and Lima Beans)—Classification of

Types of Lima Beans—Table Showing Relationship of Types of

ima, Beans. s.¢ cain veces seh erne alta s. dan sho ae es 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

SPOGIES citi distin cseaandalitoneiar Geen obtndads ab iatelh n tande A mlormielorae Ss 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)........... 2.0.00... cee eee ee 432
Trifolium (Clover)—Generic Decckiption—Geonaplical—

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................-..005 434-435

Trifolium incarnatum (Crimson, Scarlet, or Italian Clover) —
Description—Geographical, and Uses—Environmental Rela-
TIONS ec tinaets yer degeas aed es cutee: RONEN eat SS eet heh 435-436
Trifolium pratense (Common Red or Purple Clover)—
Habit, Stems, Roots—Leaves—Inflorescence and Flowers—

CONTENTS XV

Fruit—Pollination—Gevgraphical—Environmental Relations

—Mammoth Clover—Uses............... 000 cece scene eee 430-440
Trifolium medium (Zigzag, Medium Red, White, Mammoth

or Meadow! Clover) isiiaxcc: nated yee. eee ge des eee hocks 441
Medicago (Medics)—Generic Description—Geographical—

Key to Principal Species of Medicago...............-.---. 441-442

Medicago sativa (Alfalfa, Lucerne)—Roots—Stems—‘‘Cut-
tings” of Alfalfa—Leaves—Inflorescence—Flowers—Pollina-
tion—Factors Affecting Seed Production—Fruit—Germina-
tion and Seedling—Geographical—Types of Alfalfa—Environ-

mental Relations—Uses and Production................... 442-449
Medicago lupulina (Hop Clover, Black Medic, Yellow Trefoil).449
Medicago arabica (Spotted Bur Clover).................... 449-451
Medicago hispida (Toothed Bur Clover)................... 452
Melilotus (Sweet Clover)—Generic Description—Species of
Melilotusyie32.2.4ui ildualis sinc daddd oe bpidennmn tek Giulen ee Mok 452-454
Melilotus alba (White Sweet Clover)—Description......... 454
Melilotus officinalis (Yellow Sweet Clover)—Description—
Environmental Relations—Uses of Sweet Clovers).......... 454-455
Soja (Soy Bean)—-Generic Description...................4. 455-456
Soja max (Soy Bean, Soja Bean, Coffee Bean)—Description—

S685 ca exited seis aed ae La eae Ane WAR ORE ER ath cee 456-458

Vigna (Cowpea and Related Species) —Description—Species..458-460
Vigna sinensis (Cowpea)—Description—Environmental Rela-
HONS —USES sy oelsiaia-ceann wehitiod ade Saiiveaes andeend avenrinatdeiarde cians 460-462
Arachis hypogoea (Peanut, Goober)—Habit, Stem—Leaves—
Flowers—Development of Fruit—Fruit—Types—Environ-

mental Relations. x9: sasaqeens ged elas Hema Seeks Saaweas 462-465
Less Important Legumes............0 00... eee eee eee 465-467
IRELELEN CES. 5. csaise Senter Sisvastatie nian} Sucsk dene bdd dug. fob deabenrbac ndash 467-468

CHAPTER XXX.—LinaAceE# (FLax FaMity)
Habit, Stem, Leaf—Inflorescence and Flowers—Fruit—The
Names Derived from ‘‘Linum”—Geographical, and Environ-
mental Relationsisjess << .acaina esas caine kes 5 we arhee soaks 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.—RuvtTAcEz (RUE Famity).
Description—Key to Important Genera of Rutacez........ 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-

TOW oi nds earn ke « puted wanes pt eld d ao EERE SOOO OURAN 480-481
Citrus limonia (Lemon)—Description—Geographical—Color

of Lemon Fruit—Uses.......... 2. cece cece eee tenn e ones 481-483
Citrus aurantifolia (Lime)—Description—Geographical—
SPLimequat isso: caayegen ¥:. acumen wreiaye Peachy ¥ earedarNure te erent at 483
Citrus sinensis (Common or Sweet Orange)—Description—
Geographical—Types—USeS... 0.0.0... esc e eee eee nee 484-485
Citrus nobilis (King Orange)—Description—Varieties...... 485
Citrus grandis (Grapefruit, Pomelo, Shaddock)—Description
—Geographical—Variety and Name.................00eee5 485-487
Citrus aurantium (Sour or Seville Orange)—Description—
Geographical—Other Species of Citrus.................00.. 487
Fortunella (Kumquat or Kinkan)—Description—Species—

MSCS a eiips ives. gas esta ceases aosce tees by sadve eneabra, Rete Seasasust hd. ances daneaseees 487-489
Poncirus (Trifoliate Orange)—Description—A Hardy Orange.489
References ys seid ated spoeeregtn ae tee Se geese eens 489-490

CHAPTER XXXII.—VitacEz (GRAPE FAMILY).

Family Description—Geographical—Key to Important
GeMer anes 35 Soria. ilgalisd nae vena ac oattoe Maadna GAMING aselesee Bane Sade 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..........------ eee eeeee 492-504

CHAPTER XXXIII.—Matvacez (MALLow Famity).

Habit—Leaves—Flowers—Fruit and Seeds—Geographical—
Economic Importance—Key to Important Genera of Mai-
VACOBH bandas och daw shoe OR oe ee ee 505-508
Gossypium (Cotton)—Habit of Plants, and Roots—Stems—
Leaves—Flowers—Pollination, Fertilization, and Development
of the Fruit—Fruit—Seeds—Cotton Fibers Distinguished from
Other Common Textile Fibers—Species—Wild Cottons—
American Cottons—Types and Varieties—Environmental
Relations—Picking and Ginning of Cotton—Bleaching of
Cotton—Uses of Cotton—Importance and Production of

Cotton...... FA fg baie cps et) ca ass Mastin hc ot &ctuanlteacinavave Woe ee aeaORe AGS 508-527
Hibiscus esculentus (Okra, Gumbo)—Description—Geo-
graphical—Types—Uses. .........6- esse eee e eee wen eees 527-528

REfCTENCES soon eee es a. alerts BN aA aoecos Sela edaeA RSS 528-529

CONTENTS Xvi

CHAPTER XXXIV.—UMBELLIFER& (CARROT FAMILY).
Stems and Leaves—Inflorescence and Flowers—Fruit—
Geographical—Key to Genera of Economic Importance. ...530-533
Daucus carota (Carrot)—Habit, Root and Stems—Leaves—
Inflorescence and Flowers—Fruit and Seed—Geographical
Varieties Uses :ji0.0 2.54 wenicisisniea.g 4 bteenaalinads x avhemcmentaute 533-530
Pastinaca sativa (Parsnip)—Habit, Roots, and Stems—Leaves
—lInflorescence and Flowers—Fruit and Seed—Geographical

sVariehlese.ix'cad waydain a ieree nuaeuad orca aveanns were ldaudeleler es 536-538
Apium (Celery and Parsley)—Generic Description—Geo-
graphical—Key to Principal Species of Apium............. 538-539
Apium petroselinum (Parsley)—Description—Varieties...... 5390-540
Apium graveolens (Celery and ,Celeriac)—Description—Geo-
graphical—Types and Varieties—Uses.............--000005 540-542
REFERENCES ccc ccsses anes eiecicaresel ne weir asirg cae A ere w wrenel ed aridiwices 542
CHAPTER XXXV.—Vaccini1aceEz& (HUCKLEBERRY FAMILy).

Habit—Leaves—Inflorescence and Flowers—Fruit.......... 543-545
Vaccinium—Pollination—Fruit—Geographical—Key to Chief
Fruit-bearing Species of Vaccinium....................005: 545-547

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

Of 'GaylUsSaClaie. jes as: sy wasayrle-d dani headed cillealandns maces 547
Cranberries—Vaccinium macrocarpon—Types—Vaccinium
oxycoccus, Vaccinium vitis-idea.:..................00. _+ + 1548-550
Huckleberries and Blueberries...................0.0000005 550
References: ss cueie es 54 edad toc e898 SSS ES BRE RH 550

CHAPTER XXXVI.—OLEAcEz (OLIVE FAMILY).
Family Description—Geographical, and Economic Impor-

CBTAC OS ge. ays aan oral elite tot anys cave ca teeabecoulea tear eae a tvine aN 551
Olea europoea (Olive)—Description—Seed Germination—
Propagation “Uses icijces diecast a's RA Ree Eee le ewes aes 551-553

CHAPTER XXXVII.—ConvoLvuLacE& (Morninc GLory FAMILy).
Habit—Leaves—Inflorescence and Flowers—Fruit—Key to
Important Genera. ....... 0... eee eens 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.—SoLanace& (Potato Famity).

Habit of Plants—Leaves—Inflorescence and Flowers—Fruit
—Key to Important Genera...............0 0. cece eee eee ee 559-560
Solanum—Habit—Leaves—Inflorescence, and Flowers—
Fruit—Geographical—Key to Important Species of Solanum..560-561

xviii

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 ar ench y ma—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.............. 00: cece eee ee eee e eee 561-585
Solanum melongena (Eggplant, Guinea Squash)—Description

—Types and Varieties............. 0.0 cece eee eee 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...................005- 592-596
Nicotiana (Tobacco)—Habit—Leaves—Inflorescence and
Flowers—Fruit—Geographical Distribution and Economic
Importance... cc cvasy esa cess ee sean ee erro 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 iio: gene sanc ga tows ee ea wea eso ans 597-605

CHAPTER XXXIX.—CucursiTacE& (Gourp Famity).

Habit—Stems and Leaves—Flowers—Fruit—Germination of
Cucurbit Seeds—Key to Principal Genera.................. 606-610
Cucurbita (Squash, Pumpkin, Gourd)—Stems, Leaves,
Flowers—Pollination and Fertilization—Mature Fruit—

Geographical—Key to Important Species of Cururbita....... 610-612
Cucurbita pepo—Description—Origin—Types and Varieties . 613
Cucurbita maxima—Description—Types and Varieties....... 614°
Cucurbita moschata—Description—Types................. 615

Cucumis (Muskmelon, Cantaloupe, Cucumber)—Stems,
Leaves, Flowers—Pollination—Geographical—Key to Prin-
Cipal' Species: i. sass. ays oak ord weeintace eres ved Paes 615-617

CONTENTS xix

Cucumis melo (Muskmelon, Cantaloupe, Melons)—Descrip-

tion—Botanical Varieties of Cucumis melo................ 618-620
Cucumis sativus (Cucumber)—Description—Geographical—
—Closcly Related Forms—Types—Pickles................. 620-622
Cucumis anguria—Description................ 00... e ee eee 622
Citrullus (Watermelon, Citron, Colocynth)—Description—
Geographical ei gg eisncd eciacess S aues oo a Hie a mchae Weep Gnas 622-623
Citrullus vulgaris (Watermelon, Citron)—Description—Geo-
graphical—Types and Varieties.................. ....00-- 622-624
FRELET ENCES 5.5. 5. ces tee dlante a nate eadehincs ace wasp dean chaneneranioie dada 3 624

CHAPTER XL.—Composit& (THISTLE FAMILy).
Habit—Leaves—Inflorescence—Flowers—Key to Important
Generaitecos sss wets oe ns geek he eren pean sa we adue aie 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—
GeO gra Pleas scnias wciiaro ans avsnaraean ame nenee strona ead aonees 635
Cichorium intybus (Chicory or Succory)—Description—Uses,

and Varletlesinc sc: cccaaces cen aioe. able ng men ae eeaukan ener 636
Cichorium endiva (Endive)—Description—Geographical
Distribution, and Economic Uses.................-.0000005 636-638
Helianthus tuberosus (Jerusalem Artichoke)—Description—
Geographical—Closely Related Species—Uses.............. 639
Referen C6855 s.cb cscs ening caer tiated p Seeentey oie end dekard ete 639
GIOSS AL Yiien'ce:sours asians Pecans Haag re PRONE eee Sela aes 641-651

INDE ete 5 2 ete Fee e reales wine eters yee a heey a hee 653

BOTANY OF CROP PLANTS

PART |

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 alge
(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 alge
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 (Hepatice).

Principal Parts of Seed Plant Body.—The parts of the
plant body may be classified according to the work they do,
into two groups: (1) 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,

I

2 BOTANY OF CROP PLANTS

transpiration, ctc., 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 érees, shrubs and
herbs—plants which differ much in form and habit. Trees
and shrubs are woody, while herbs possess less woody tissue

THE SEED PLANT BODY 3

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

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 réle 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 English lens
manufacturer. In his microscopic study of thin sections of
ordinary bottle cork, in 1667,.he observed the cork tissue to
be composed of very small compartments, very much alike
in size and shape, and fitting closely together. It happens

4

FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 5

that the separate units making up the cork tissue resemble
the cells of a honeycomb, and hence Hooke gave the name
“cell” to the units of cork tissue. Although aninappropriate
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-living portions are products
of the living material within the cell.

The Cell as a Unit of Plant Activity—tThe 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, alge, 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 live and reproduce when separated from its neighbors. In

6 BOTANY OF CROP PLANTS

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

The Structure of the Plant Cell (Fig. 1)—It must be
understood at the beginning that plant cells vary a good deal
in size and shape. - However, the fundamental structure of
all plant cells is much the same. The plant cell consists of
a living mass (protoplast) of protoplasm enclosed in a non-
living cell wall. The wall is manufactured by the protoplast,
and serves as a protection to it. If we examine the proto-
plast, we see that it is composed of rather definite parts.
There is an outer, thin, and transparent living membrane
about the protoplast, which is only made manifest by treating
the cell in a special manner. This membrane is known as the
protoplasmic membrane, ectoplasm or hyaloplasm. It is all-
important in the intake and outgo of substances. Ifa 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

‘ow?

cs

Fic. 1.—A, young cells from onioyroot tip; d, protoplasmic membrane; c,
cytoplasm; a, nuclear membrane; % nucleolus; e, plastids (black dots). B,
older cells farther back from the root tip; f, 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 cellsap. This phenomenon iscalled 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.

8 BOTANY OF CROP PLANTS

All vacuoles are bordered by a protoplasmic membrane, simi-
lar to the ectoplasm.

Suspended within the cytoplasm are specialized living
bodies, the plastids, also numerous granules, which may be
of living material and insoluble food particles, such as starch
or protein. The cytoplasm may hold insoluble crystals of
salts, chiefly calcium oxalate. Let us arrange the parts of
cell thus far described in outline form as follows:

( Cell wall aired
| { Protoplasmic membrane (living)
Nucleus (living), containing one or more nucleoli
Elaubeel | Protoplast. ( plastids (living)
| granules (living or non-living)
crystals (non-living)

| cytoplasm. |

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: (1) 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-like, rather
granular substance, resembling very much the white of an
egg. It feels slimy.

Protoplasm is a very complex chemical substance. Al-
though no element has ever been found in protoplasm that
is not also found in the common substances in the world
about us, the exact arrangement and proportions of these
elements has not been ascertained, except in a general way.
It is quite clearly established that protoplasm is a proteid,
of complex nature, with water as a solvent. Proteids form
about one-half or two-thirds of the dry substance of pro-
toplasm. The remainder is fat, sugar, and other carbohy-
drates, organic acids, organic bases, and some mineral
substances.

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 1
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

pie)

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

|
-Ist bye

+ coleoptile

Fic. 2.—Three germinating stages in wheat.

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

12 ; BOTANY OF CROP PLANTS

tious roots will appear at the cut surface, and by develop-
ment, form the characteristic root system of the plant. Some

~~ “ground Tinz

‘crown or
fl permanent roots

~

Fic. 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 1 inch below the soil surface.

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

ROOTS 13

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

GROUND LINE
ay ge ~
>. a ag. we
S 5 ome Baie:
ah at LT. , Y)
=a) ”

Fic. 4.—Tap-root system of young sugar beet. (Maxson.)

parent stem and such rooted tips used as “‘sets.”’ Straw-
berries produce slender stems, called runners. Adventitious
roots may be produced at the nodes.

A very different sort of root system develops in such plants

I4 BOTANY OF CROP PLANTS

as the beet, radish, turnip, parsnip and carrot. In the germi-
nation of the beet seed, for example, the primary root pushes
out, takes a straight downward course, and gives off a few
lateral roots. Hence, the primary root system of the beet
consists of one main root extending downward, with a few
fine laterals. Adventitious roots do not arise, as in wheat,
nor does the primary root system die, as it does in wheat,
but the main iap root of the young plant continues to elongate,
and to give off lateral roots and rootlets (Fig. 4). The
‘‘beet”’ itself is for the most part an enlarged tap root. The
tap root of the sugar beet may reach a depth of 4 feet, and
often 6 or 7 feet. The upper laterals are the largest of the
branch roots and extend farthest in the soil, spreading almost
horizontally 2 to 3 feet. The lower laterals are more vertical
and those near the very tip are almost parallel with the tap
root. A root system such as possessed by the beet, radish,
turnip, parsnip, carrot, dandelion, red clover, and many
other plants is called a tap-root system.

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

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

ROOTS TS

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 soca
root system. Fruit trees, endoderms .” Periblem
for example, send their ben dermatogen
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 region of,”
an index of soil conditions. Téfi'muyphcato \
General Characteristics
of Roots.—It will be re-
called that the seed plant
body possesses a number Fic. 5.—Median lengthwise section of
of members, each with the apex of a root of barley. (After
Strasburger.)
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

16 BOTANY OF CROP PLANTS

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

Classification of Roots Based upon Their Medium of
Growth.—The medium of growth of most roots is soil. Such
roots may be called soil roots. It is customary for us to
think of the root system of a plant as growing in the soil,
just as we associate the shoot system with the air above
ground. However, not all roots live in the soil, and not all
shoots live in the air. There are water roots, and air roots,
as well as the ordinary sort, soil roots. Water roots occur
in such floating plants as the duckweeds, water hyacinth
(Eichhornia speciosa). Water roots produce but a few
branches. They possess no root hairs; absorption takes place
through any cells on the surface. Air roots occur in many
plants, such as corn (Fig. 56, B), Virginia creeper, tropical
orchids, the banyan and other species of Ficus. Air roots are
wellshownincorn. 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 erial
roots, they are unbranched, but they branch profusely when
they strike the soil. They have the réle 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) Jength-
wise section of a young root. It will appear as in Fig. 5.
We shall see then that the root has a cap of loose cells at the

ROOTS

17

tip. This protective structure is called the root cap. Just
back of the root cap is the region of greatest cell multiplica-
tion (Fig. 5), composed of cells that are actively growing.
The very tip of the cap is continually sloughing off, while

new cells are being added to it
just in front of the growing point.

In addicion to the root cap we
note that there are three distinct
parts to the root, namely, (1)
dermatogen, an outer. layer or
layers; (2) plerome (axis); and (3)
periblem, between the dermatogen
and plerome. The dermatogen
becomes the epidermis, the plerome
the stele or central cylinder, and
the periblem the cortex. It is
often possible to strip the cortex
and epidermis from the central
cylinder, which is composed of
tough, fibrous tissue.

The cortex (Fig. 6) is composed
of large, thin-walled cells, which
do not fit closely together, but
leave air spaces (inter-cellular
spaces) between. The innermost
cortex layer is called the endo-
dermis. The outer cortex cells
may become prolonged to the side
to form root hairs. The central
cylinder or stele (Fig. 6) is bounded

secondary phloem.

Fic. 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; 0b, primary
phloem bundles. 3B, cross-
section of older portion of
root; lettered as in A; )b’,
(After
Vines.)

by a single layer of cells, the pericycle, which lies adjacent

to the endodermis.

ing bundles or strands.
2

Within the stele are found alternat-
The woody, water-conducting bun-

18 18

BOTANY OF CROP PLANTS

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

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

Root Hairs—the Absorbing Organs of a
Plant.—The great problem of all our com-
mon plants is to take in as much water from
the soil as they lose to the air, z.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

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

ROOTS 19

the plant through root hairs, which are found near the tips of
the smallest rootlets. In reality, the root hairs are the ab-
sorbing organs of a plant. When we pull up any common
herbaceous plant, we observe, as a rule, a large number of
hair-like rootlets as branches of larger roots. These fine
“hair roots” are sometimes mistaken for root
hairs. But, closer examination, in which a
hand lens may be necessary, shows us that
these hair roots are the bearers of root hairs.
In fact, root hairs are found only on the |
smallest and youngest rootlets. |
Root-hair Zone.—Root hairs do not grow
along the full length of a rootlet, but occupy
a definite zone, designated the root-hair zone.
This is clearly seen in young 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 soilis 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- _ Fic. 8.—Wheat
7 7 : . seedling showing
times partially surrounds, the soil particles soil particles cling-
with which it comes into contact, thereby oe
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

20 BOTANY OF CROP PLANTS

weeks. New hairs are constantly formed anew at the an-
terior end of the root-hair zone, while those at the posterior
end are dying. Root hairs do not become roots.

Structure of a Root Hair.—The root hair is a single cell.
It is a simple, lateral prolongation of a border cell of the cor-
tex (Fig. 9). It has the shape ofa 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

Fic. 9.—Root hairs. (After Ga ger.)

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
H airs.—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. 1) 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 modes, the enlarged joints between
the internodes, give rise to leaves, and if we follow the wheat
plant through its life, we observe that the stem terminates
in an inflorescence (flower cluster). Now, in addition to-the
one main stem that arises as a prolongation of the embryonic
stem in the seed, branches arise from the lower nodes. These
branches arise in the axils of the lowermost leaves, in most
cereals. In cereals, this branching is known as “stooling”’
or ‘‘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

22

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. T-he
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 /eaf bud, we find a very much shortened axis
or stem bearing a number of small leaves. As the leaf bud
is a young shoot, it may as properly be called a branch bud.
That is, it elongates into a branch which bears leaves. The
new shoot, just as the old one from which it came, ends in a
bud, and in the leaf axils other buds arise. If we open up a
flower bud, we find one or more young flowers. In plums,
for example, the number of flowers in a bud varies from one
to five, two and three being the most common numbers
(Fig. 166). Mixed buds contain both flowers and leaves.
The terminal buds at the ends of the short “spurs” in the
apple are mixed buds (Fig. 153).

It is not always possible to distinguish leaf from flower

24 BOTANY OF CROP PLANTS

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

Buds may be classified as to their position on the stem into:
(a) terminal, (b) lateral or axillary, (c) accessory or super-
numerary, (d) adventitious, and (e) dormant.

Most stems end in a bud. Such a terminal bud is almost
always a leaf bud; occasionally it bears flowers, too, as in the
apple. The terminal bud is normally the most vigorous of
all on the stem, as is evidenced by the fact that it elongates
into a shoot which exceeds in length those from the lateral
buds. Lateral (side) buds arise in the leaf axils. They give
rise to side branches or to flowers. Accessory or supernumer-
ary buds are extra ones coming out in the leaf axils. They
are best shown in the maples and box elder. Adventitious
buds arise out of order, in unusual places, not in leaf
axils or at the end of a stem. They are usually stimu-
lated by injury. For example, when a branch is cut back,
numerous adventitious buds develop about the edge of the
cut surface. Dormant buds are ones that have arisen in a
regular fashion in the leaf axil, but which, for some reason,
do not develop. Hence, they may be grown over with the
succeeding layers of wood and lie buried within the tissue in
a latent condition. Such a bud may be called into activity
later in the life of the plant and come to the surface. It
would appear to be endogenous in its origin, while in reality
it is exogenous. Irregular branching may result from the
development of dormant buds, or as is more commonly the
case, from the development of adventitious buds.

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 onan
apple, peach, or citrus tree,
for example, differ from
each other in important
respects. That this differ-

STEMS

25

j ‘ flower- buds

\ stipule-scar

§-----ferminal bud- scar

i ..._ Flower-bud-scars

Fic. 10.—Cottonwood twig two years

old. (After Longyear.)

26 BOTANY OF CROP PLANTS

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

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

General Characteristics of Stems.—Let us now examine a
winter twig of the cottonwood, for example, that is several
years old, such as pictured in Fig. 10. 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 Jeaf
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 27

the limits of two successive years’ growth are marked by
bud scale scars of terminal buds. In this way we may
determine the age of a twig.

Close observation of the twig will reveal a number of
whitish spots on the bark. These are lenticels (Fig. 11),
structures on the stem composed of a mass of loosely fitting
cells which permit the diffusion of gases inward and outward.
Except for the lenticels, the bark prevents the free passage
of air, and also the loss of water from underlying stem parts.

Fic. 11.—Section of the lenticel of elder. (After Strasburger.) 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 foliage leaves and flowers. Both

STEMS 29

underground and aerial stems are possessed by suchcommon
plants as Irish potato, onion and asparagus:

Water is also a medium of growth of stems, as is the case
with such plants as Elodea, Potamogeton, water lilies, etc.

“Modified” Stems.—Undoubtedly, the ordinary cylin-
drical twig such as is found in trees and shrubs is the most
common sort of stem. It is quite likely that we think of a
stem as a plant part growing more or less erect, in fact, most
stems do tend to grow erect. However, all stems are not as
just described. As we take a survey of the plant kingdom,
we discover many different forms of stems—stems that are
so different from the ordinary sorts that they are scarcely
recognizable as stems, and are identified as such, only by
careful study of their origin and structure. Among such
stems are the following:

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

30 BOTANY OF CROP PLANTS

stocks are broken into a number of separate pieces by
cultivating implements, each piece may develop adven-
titious roots, establish itself, and send up leafy shoots. Fre-
quent cultivation that has as its aim the destruction of new

= decurrent

\ leaf base
j —aerial stem
OO Og ay Se ae es
whizome
7

= LIKES a
POF ce i ey

i . Lr paing tubers
Sey 4

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

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

STEMS_ 31

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

2. Tubers——These are fleshy, underground stems. The
best example is common Irish potato. Although the potato,
ordinarily, would not be considered a stem, still if we follow
through its development, and examine its structure, we are
convinced that it is stem (Fig. 12). When we plant a
slice of a potato, ‘‘sprouts’’ are soon sent out from the
“eyes.” These sprouts, with their nodes, and internodes,
and their scale leaves, are quite obviously horizontal under-
ground stems (rhizomes). Soon,
the tip of a rhizome begins to en-
large, and a potato is formed;
hence, the potato is seen to be a
simple enlargement of the tip of an
underground stem. Furthermore,
examination of the tuber reveals
the presence of a terminal bud
(‘seed end’ of the potato), and
lateral buds along the sides. The
buds are the so-called ‘‘eyes.”
In an elongated potato, we may
be able to detect the spiral ar- 3, er ne
rangement of the buds. Lenticels showing a shedding leaf; also

bark, wood and pith as seen
may also be observed on the corky in cross and longitudinal sec-
layer (skin) of the bark of the tions. (After Longyear.)
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. ‘

i

32 BOTANY OF CROP PLANTS

3. Bulbs ——A bulb is an underground stem. The common
onion is a typical example. A median, lengthwise section
(Fig. 14) of the onion bulb, shows a small, cone-shaped stem
upon which are numerous,
fleshy leaves that are over-
lapping and quite rich in food
material. Here, too, there is
a terminal bud, and lateral
buds occasionally in the leaf
axils. Brlbs are vertical
stems, thus differing from the
horizontal direction of growth
of rhizomes.

4. Corms.—A coim is a
short, solid, vertical, under-
ground stem. It is typically
exemplified in gladiolus.
Corms are usually flattened
from top to bottom, and bear
a cluster of thick fibrous
roots at the lower side, and a
tuft of leaves on the upper
side. Corms are storage
organs.

5. Runners (stolons).—
These resemble rhizomes in
Fic. 14.—Median lengthwise section that their direction of growth

Se eee SER EHles 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

STEMS 33

strawberry plant. They are attached to the old plant for
but one season. Runners may branch.

6. Lianas.—A liana is a climbing stem, gaining mechanical
support only from another plant. Common lianas are the
grape, Virginia creeper, hop, Japan ivy (Psedra tricuspidata)
and morning glory. The stems of lianas are slender, long,
and have insufficient’ strengthening tissue to hold them
perfectly erect. Hop stems always wind about the support
clockwise (Fig. 102). Such a twiner is destrorse. The twin-
ing stem of Virginia creeper bears fleshy, yellowish air roots
which may aid the plant in adhering to its support. Of
greater value to the Virginia creeper plant, in this regard,
however, are the highly specialized branches—tendrils. In
this case, a tendril ends in a knob which flattens out, when
it comes into contact with a surface, and adheres to that
surface by a mucilaginous disk-shaped structure.

7. Spines—Some spines are reduced stem structures, as
is the case in the honey-locust, hawthorn, wild crab, etc.
Many small spines, such as are found in gooseberries, cacti,
and roses, for example, are outgrowths of the stem. It
seems that spines are induced by an excessive loss of water
from the plant, and a low absorption rate, such as occur
under desert and semi-desert conditions.

STRUCTURE OF STEMS

The Young Dicot Stem.—Let us cut a middle lengthwise
section of a young dicot stem (Fig. 15). This section will
cut the growing point (bud) of the stem, and the older parts
back of the growing point. We see that the stem becomes
progressively older farther and farther back from the tip.
The cells at the growing point make up a tissue known as
meristem tissue (undifferentiated tissue). Although they

3

34 BOTANY OF CROP PLANTS

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

H
7 \)
round meristem\\
3"
asi
g oO
2)
Om
he
NH a =
=O}
7
+716)
be
EO;
3)
eral a
| rel
= 5
ambium * '( Kyl
ylemfrom the procambium
Vi Mem trom oe Ayden from the cambium .
Phioem. from the procambium and cambium Phloem from the procambium and cambium

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

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

STEMS

35

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.

Phioem—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,

AYA

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

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

36 BOTANY OF CROP PLANTS

vertically elongated, but they do not reach any consider-
able size.

Functions of Phloem Elements—The functions of these
three elements of the phloem are as follows:

1. Sieve Tubes—Conduction of soluble carbohydrates,
amido-acids and proteins.

2. Companion Cells—Although sieve tubes lose their
nuclei before the end of the first year, they do not die; hence,
it is thought that companion cells extend their influence to
the sieve tubes, enabling them to carry on the life processes
for which a nucleus seems necessary.

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

Cambium.—The cambium layer ts 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. 16)—There are the fol-
lowing sorts of tracheal tubes:

1. Annular Tracheal Tubes—Here and there in the tube
are thickened rings of lignin, which have the appearance of
barrel hoops.

2. Spiral Tracheal Tubes—The thickening material is in
the form of a loose spiral.

3. Reticulated Tracheal Tubes—In these, the
strengthening material is laid down in such a
fashion as to form a network on the wall.

4. Dotted or Pitted Tracheal Tubes——In these,
lignin has been deposited over the inner wall in
such a manner as to leave numerous circular thin
places, which give the tube a dotted or pitted
appearance.

Tracheids (Fig. 17) are single cells, elongated
and modified. They-have thick, lignified walls
with numerous bordered pits. In shape tracheids
are like a spindle, and they fit closely together
making up a strong supporting tissue. rapes ae '

Wood parenchyma cells are usually thin-walled _ with bor-
and with unbordered pits. i

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.

38 BOTANY OF CROP PLANTS

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

Growth in Thickness of Dicot Stem.— Medullary ray cells
give rise to cambium that joins with the cambium in the
vascular 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: (1) 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.
Tf 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 39

1. Wood, on outside of old wood.

2. Phloem, on inside of old phloem.

3. Cork, on inside of old cork.

4. Secondary cortex, on outside of old cortex.

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

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

2. Cambium of vascular
bundle.

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

4. Pith.

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

Monocot Stems.—The Fic. 18.—Cross-section of cornstalk
corm stalk is an excellent Steps ¢ <pidemis: }. ores aad pert
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 (1) simple enlargement of cells
derived from primary meristem tissue, and in some instances

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, z.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 (1917). “Soft wood” is usually oné which grows
rapidly, and is diffuse porous, that is, tracheal tubes are
rather small and uniform in size and evenly distributed
throughout the year’s growth. ‘‘Hard wood’? is usually a
comparatively slow-growing wood, and is ring porous, that
is, the tracheal tubes of the spring and early summer are
large and numerous, while the autumn wood is solid as a
consequence of the relatively greater abundance of tracheids
and wood fibers.

Bark.—The term ‘“‘bark”’ with us includes all that portion
of the stem down to the cambium layer. When the bark
of a tree is peeled off, there are removed the following
layers in order from outside to inside: cork, cork cambium,
cortex, phloem, and portions of cambium. The cleavage line
is the cambium zone.

STEMS 41

The Work of Stems.—(1) 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:
blade 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 leafis said to be sessile. Vascular bundles run
from the stem out through the petiole into the blade, where
they branch to form the network of veins. The veins not
only carry water, solutes and food materials, but also form
a framework for the softer tissue of the leaf.

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

42

LEAVES

43

As examples of the latter, may be mentioned the small,
scale leaves on underground stems, the scales enwrapping
the growing point in buds, the bracts in grass inflorescences,

and the petals, stamens and car-
pels of flowers.

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

Leaves may function as (1)
food-making organs (foliage
leaves), (2) protective structures
(scales), (3) reproductive organs
(floral organs), and (4) as storage
organs. The fleshy leaves that
make up the bulb of onion are
good examples of leaves used for
storage.

Foliage leaves are either par-
allel-veined or netted-veined. In
leaves with parallel venation, there
are many veins, about equal in
size, running parallel, and joined
by inconspicuous veinlets. This
type of venation is characteristic
of the leaves of grasses, sedges,
rushes, lilies and most all other
monocotyledonous plants. In
leaves with netted venation, which

“Yendr Is

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

is so well illustrated in leaves of apple, oak, maple, potato,
cabbage and other dicotyledonous plants, there are a few

44 BOTANY OF CROP PLANTS

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

Leaves are often classed as simple or compound. The apple
leaf is an example of a simple leaf (Fig. 159). In this there
is an undivided blade. The bean, pea, carrot or parsnip leaf
is compound (Fig. 19). The blade is divided into a number
of segments, or Jeaflets.

We may classify leaves as to their arrangement on the
stem. Leaf arrangement is the same as bud arrangement,
for ordinarily a bud arises in the axil of each leaf. They
may be alternate, opposite or whorled (see page 25).

Leaves vary widely in size, shape, character of margin, and
base, texture, thickness, nature of epidermal coverings, etc.
Some of these variations will be mentioned throughout the
pages that follow.

Structure of Leaves.—The structure of a leaf is best shown
in a cross-section (Fig. 20). The upper epidermis, usually
consists of a single row of cells. Below it, is the palisade
layer, composed of one or more rows of cells the long axes
of which are perpendicular to the leaf surface. Below the
palisade cells is the spongy parenchyma, varying in thick-
ness, and composed of rather irregularly shaped cells that
fit together loosely, thus leaving intercellular spaces (air
spaces). The lower epidermis is seldom more than one layer
of cells thick. Chloroplastids are abundant in palisade and
spongy parenchyma cells, but absent from all epidermal cells
except the guard cells of stomata.

The outer wall of epidermal cells is normally thicker than
radial or inner walls. Cutin, a fatty substance, highly im-
pervious to water, is deposited on the outer wall, to form a
layer called the cuticle. A thick cuticle is a common char-
acteristic of leaves growing in arid situations. The same
variety will develop a thicker cuticle under arid conditions

LEAVES 45

than when growing where there is ample water. A_ thick
cuticle is a good drought-resistant character.

The epidermal cells do not form a continuous layer over
the two leaf surfaces. There are numerous pores or open-
ings, the stomata (singular stoma, a mouth) (Fig. 20). Each
stoma is bounded by two modified epidermal cells, differing

Om
(4

¥
fal teade parench) ma

WEY

SSE
SS € pies s

Fic. 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 defoliation through any cause, or
from disease of leaves, or from their meager development.
We have learned to associate an abundance of bright green
leaves with plant vigor, just as we associate a rosy com-
plexion with health in people. And, with but few excep-
tions, we may judge Of the health of a plant by its leaf
development and color.

Carbohydrates are made by green plants only, and only
by those cells of green plants that possess chlorophyll. The
cells of roots and other underground plant parts, and all
those cells of the plant so far removed from the surface as to
be beyond the influence of light, do not have chlorophyll,
and hence, have no power of making carbohydrates. Other
than that in the relatively small amount of green tissue in
young stems and in the sepals of flowers, all the carbohydrate
of the plant is made in the chlorophyll-bearing cells of leaves.
The manufacture of carbohydrate by green tissue is called
carbohydrate synthesis or photosynthesis. When we realize
that carbohydrates form the basis of all the other more com-
plex foods of the plant body, such as fats, amides and

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 stréam (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

Fic. 21.—Flax. A, floral diagram—
c, calyx; co, corolla; s, stamens; ?, pistil. .
B, median lengthwise section of flower.
C, calyx and corolla removed. D, fruit,
external view. £, cross-section of fruit.

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

1. Calyx, made up of
sepals, which are green,

‘and enclose the other

flower parts in the bud.

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

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

4. Pistil, which has a
swollen basal portion, (1)
the ovary, (2) astyle, slen-
der stalk leading from the
ovary, and terminating in
(3) a stigma, which is re-
ceptive to pollen. Within
the ovary are the young

ovules, the bodies which become seeds.

48

FLOWERS 49

All the flower parts mentioned above, in the representative
flower, are attached to the end of the flower stalk, the
receptacle or torus. The calyx and corolla taken together
constitute the perianth.

We shall see that there 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

oe

C/

Fic. 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.)

eappear in the order named, as described in the case of the
apple flower on page 366. This order of floral succession is
said to be acropetal. Although this is the prevailing order,
there are different types. For example, in some mustards
the petals are the last to appear, and in some roses the carpel

primordia appear before the stamens.
Stamens.—Ordinarily, the anther is held upon a filament

4

50 BOTANY OF CROP PLANTS

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

Mature Pollen Grain.—When the pollen grain is mature,
it consists of a wall surrounding a protoplasmic mass, the
essential parts of which are a tube nucleus and a generative
nucleus. At the time of pollen germination the latter di-
vides into two sperm ex 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 51

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.

pericarp ——7+

a
antipodals

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

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

52 BOTANY OF CROP PLANTS

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

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

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 placente are on the ovary wall. Such placentation
is said to be parietal. In lilies (Fig. 31A), the placentation
is axial, or central, that is, the placente 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-

54 BOTANY OF CROP PLANTS

metrical halves by any diameter (Figs. 156 and 162). Such a
flower is said to be radially symmetrical, or actinomorphic,
or regular. Contrast this symmetry with that in such flowers
as the pea or bean (Fig. 172A), 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 sais in cuinst aposepalous synsepalous
Petalsivsnceus caches apopetalous sympetalous
diadelphous (2 groups)
Stamens) scene vad polydelphous monedelphone @ eomp)
Carpels. ie cceas ais cee 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 “dze-
cious.”’ In some dioecious species (hops), the staminate
and pistillate inflorescences are very unlike in appearance,
while in other dicecious 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 “monecious.” 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: (1) simple, (2) indeterminate or racemose, and (3)
determinate or cymose.

The simple type is well represented by the calla lily or
tulip, in which one flower terminates the stalk. Mustards
and currants have a typical indeterminate or racemose in-
florescence. In this, the older flowers are at the base or
outside of the flower group and the younger appear in order
above them. Moreover, the growth of the ‘inflorescence
may continue at the apex. For example, in a cabbage or
radish inflorescence, flowers may be opening at the tip, while
at the base pods are partially mature. Racemose types of
inflorescences are the true raceme, panicle, corymb, umbel,
spike, and head. These will be described when they are
met with in the family descriptions that follow. The cymose
flower cluster is one in which the older flowers are on the in-
side, and the younger appear in order toward the outside. The
length of a flower shoot is determined by the terminal flower.
The inflorescence of chickweeds is a cyme.

CHAPTER VII
FRUITS, SEED, AND SEEDLINGS

Development of the Seed.—We have seen how a male
nucleus of the pollen tube unites with the egg or embryo
(female) nucleus of the embryo sac. The fertilized egg
then starts upon a series of divisions, and by growth and
development, the young plant or embryo is formed. It
may be partially or totally imbedded in the endosperm.
In some seeds (bean), the endosperm is lacking, and the
embryo occupies the entire space within the seed coats. The
cells of the nucellus are in part absorbed by the developing
embryo, and at most the nucellus is represented by a very
thin and compressed layer just within the inner integument.
The integuments of the ovule become harder, less permeable,
and form the seed coats. The micropyle is still evident in the
mature seed as a small opening.

The embryo or young plant has three main parts: (1)
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: .

{ x. Seed coats.
| 2. Nucellus.
ead | 3. Endosperm. . ae
| Growing point of shoot, with leaves (bud).

Cotyledon or cotyledons.
| Hypocotyl, terminating in the young root or radicle.

57

4. Embryo

58 BOTANY OF CROP PLANTS

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

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

Kinds of Fruits——No attempt will be made at this place
to give a complete classification of fruits. We will describe
the different kinds as we meet with them in the discussions
of crop plants. Fruits with a dry pericarp, such as the grain,
achene, capsule and pod, are designated dry fruits. De-
hiscent dry fruits (capsule, pod, follicle) split open at maturity
in a definite way permitting the seeds to escape. Inde-
hiscent dry fruits (achene, grain) do not split open at maturity

FRUITS, SEED, AND SEEDLINGS 59

in any definite way. Fruits with a fleshy pericarp, such as
the berry, are called fleshy fruits.

Germination of Seed.—The seed must have an adequate
supply of water, oxygen and a suitable temperature in order
to germinate. The initiatory stages in germination are the
absorption of water and the secretion of enzymes in the seed,
which render soluble the stored food material necessary to
nourish the growing embryo. This food may be stored in the
endosperm, as in all grains, or in the cotyledons, as in beans
and peas. The embryo is dependent upon stored food for
its initial growth. The swelling of the seed, due to water
absorption and growth of the embryo, ruptures the seed coats,
and the young shoot and primary root make their appearance.
The cotyledons are brought above ground in some plants
(beans, squashes, etc.) and constitute the temporary or seed
leaves. They may develop chlorophyll and make food for
a while. The true foliage leaves develop, partly at the ex-
pense of the food stored in the cotyledons, which gradually
dwindle away. In many plants, e¢.g., all grasses, the coty-
ledon remains in the soil. In these the first leaves are true
foliage leaves.

As soon as the first roots are established, making it possible
for the plant to absorb water and mineral nutrients from the
soil, and a few leaves are formed, the young plant is capable
of making its own food and living an independent life. It
has been tided through its early stages of development by
food stored in the seed. Generally speaking, large seeds of
any given species produce more vigorous seedlings than
small ones, and this is probably correlated with a greater
abundance of stored food in the former.

CHAPTER VIII
THE CLASSIFICATION AND NAMING OF PLANTS

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

In the early history of systematic botany, the systems of
classification were largely artificial. As the knowledge of
plants increased, one system supplanted another, and in
most cases was an improvement over the old one. One of

60

THE CLASSIFICATION AND NAMING OF PLANTS 61

the first natural systems of classifying plants (and animals)
was that of Linnaeus. The first edition of his notable work,
Systema Nature, 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 Alg@.and Fungi. The Alge 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 Alge. 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” (Pleridophytes) 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 Gymnosperme (pines,
spruces, firs, hemlocks, cedars, junipers and other cone-bear-
ing plants) and the Angiosperme (higher seed plants or
flowering plants). All the common crop plants, of field,
orchard, and garden belong to the Angiosperme. In the
Gymnosperme the seeds are. exposed, while in Angio-
sperme they are enclosed in d case, the ovary wall. Angio-
spermous plants fall into two groups (subclasses): (1)
Monocotyledones, in which the seeds have one cotyledon, the
flower parts are in threes, the leaves are parallel-veined, and

THE CLASSIFICATION AND NAMING OF PLANTS 63

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,

Angiosperme,
Dicotyledones,
Order Rosales,
Family Leguminosz,
Genus Medicago,
Species Medicago sativa.
The order ending is usually “‘ales.’’ Orders are subdivided
into families. The family ending is commonly “acee”’ or
‘“‘@,”’? Families are split up into genera, and genera into
species. The number of families, genera, and species may
be large or small.

THE PLANT KINGDOM

Thallophytes—“ Thallus plants.”
Myxomycetes—slime molds or slime fungi.
Schizophytes—“ splitting plants. ”’

Cyanophycee—blue-green alge.
Schizomycetes—bacteria.

Alga—pond scums, sea weeds, etc.
Chlorophycezee—green alge.
Pheophycee—brown alge.
Rhodophycee—tred alge.

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.”
Hepatice—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.”
Gymnosperme—lower seed plants: cycads, ginkgo, coni-
fers, joint-firs, etc.
Angiospermz—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 (pl. genera), or generic name;
the second, vulgaris, is the name of the species (pl. species) or
specific name. The letter ‘““L” following the scientific name
of the common garden bean is the abbreviation for Linnaeus.
Placed in this position after the name of the plant, it signifies

THE CLASSIFICATION AND NAMING OF PLANTS 65

that this species was 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).

5

66 BOTANY OF CROP PLANTS

Descriptive Nature of Specific Names.—Specific names
are commonly descriptive. They may be descriptive of
(x) 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 riparia, the streamside grape, riparia is descrip-
tive of this species’ habitat. The common black-cap rasp-
berry is Rubus occidentalis; here the specific name means
‘“‘western.” Again, in Vaccinium canadense, the Canada
blueberry, the specific name indicates geographical distribu-
tion. The systematist frequently uses the name of an indi-
vidual for the specific name. This may be done as a token
of friendship, or recognition of distinction, or to indicate the
finder of the new form. For example, Prunus besseyi, is
after the well-known botanist, Charles Bessey. The i
ending is the Latin genitive, signifying ‘‘of Bessey.”

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

General References

Baitey, 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

BentTHaM, G., and Hooxer, J. D.: Genera Plantarum. London, 1862-1883.

BRITTON AND Brown: An Illustrated Flora of the Northern States and Canada.
Scribners, New York, 1913.

Carp, Frep W.: Bush-fruits. The Macmillan Co., 1909.

CorsetT, L. C.: Garden Farming. Ginn & Co., 1913.

Coutter, J. M., Barnes, C. R., and Cowtss, 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 natiirlichen Pflanzenfamilien.

Hunt, T. F.: Forage and Fiber Crops in America. Orange Judd Co., 1908.

Knoutu, Pavi.: Handbook of Flower Pollination. Translation by J. R.
Ainsworth Davis. Oxford, Clarendon Press, 1906.

Montcomery, E. G.: Productive Farm Crops. Lippincott Co., 1916.

PERCIVAL, JouN.: 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: 525-530, 1905.

STRASBURGER, E., Nott, F’., ScuENcK, H., and Scurmper, A. F. W.: A Text-
book of Botany. Macmillan Co., 1912.

Ten Eycx, A. M.: The Roots of Plants. Kans. Agr. Exp. Sta. Bull. 127:
199-252, 1904.

Vitmorin, M. M.: The Vegetable Garden. John Murray, London, 1905.

Wossipto, Pavt.: Leitfaden der Botanik. Berlin, rort.

PART I]

CHAPTER IX
GRAMINEZ (POACEZ), 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 100 feet or
more. Some grasses are trailing, one or more being re-
ported as climbing over trees 100 feet high. Others, like

69

qo BOTANY OF CROP PLANTS

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

Many of our common pasture and meadow grasses, and
all the cereals, complete their life period in one season. Such
plants are said to be annual. In cool climates, certain
grasses behave as winter annuals, living through the winter
as small plants and sending up flower stalks the following
spring. So-called “winter” or “fall grasses’? behave in this
manner. A number of grasses, such as the pernicious quack
grass (Agropyron repens), lawn grass (Poa pratensis), and
others, are perennial, i.e., with a course of life extending over
three or more seasons.

Roots.—The root system of grasses is fibrous, that is,
composed of numerous slender roots of about equal diameter.
No grasses, at maturity, possess a tap-root system, as that
of radish, dandelion, beet, and others. In this there is a
strong leading central root. The primary roots, those that
arise directly from the seed, are temporary, dying after the
permanent roots are able to support the plant. The perma-
nent roots arise from that portion of the stem which ex-
tends from the germinating seed to the surface of the ground.
These roots are always produced at about the same distance
below the surface, regardless of the depth at which the seed
is planted (Fig. 3).

Grasses are classed as shallow-rooted plants. However,
great variation has been observed in the depth to which the
roots penetrate, some extending to depths which cannot be
considered as shallow. Roots of buffalo grass (Buchloe)
sometimes go to a depth of 7 feet. Rye roots have been
found penetrating to a depth of 3 feet, corn 314 feet (Fig.
56), emmer and spelt 344 feet, and wheat more than 4 feet.

Roots may break through the sheaths (that part of the

71

GRAMINEZ (POACE#), GRASS FAMILY

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

72 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

ie (internodes) (Fig. 25) which
sheath- ji are usually hollow, but some-
rowing ||| {| times filled with pith, as in
of leaf | fi| com. When young, the in-
internode At ternodes are solid, but, as

the stem enlarges, the central
portion is ruptured and a
hollow is formed. The nodes
(Fig. 25), the enlarged joints
between the internodes, are
solid. Enlargement of the
nodes is due partly to a
thickening of the leaf base at
each node (Fig. 26) and
partly to enlargement of the
stem itself. In most grasses,
ed's; 20s Barly-, 4 Portion of the part of the culm within
B, stem cut in median lengthwise the sheath remains soft and
Benne NG 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”’

node

GRAMINEZ (POACEE), 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 ‘‘mooting.” Theindividual branches are knownas ‘tillers”’

74 BOTANY OF CROP PLANTS

(Fig. 27), and the entire mass of branches is the “stool.”
Common cereals, such as wheat and oats, invariably pro-
duce a number of tillers, sometimes as many as 50. The
tillers from the primary culm may produce tillers (lateral
branches) and these in turn other tillers, so that under favor-
able conditions several dozen culms may result from a single
seed. As the internodes are much shortened, the branches

/ /= secondary stem
“primary stem

i —>serown roots
y
—-Grain remains

Seprimary roots

Fic. 27.—Diagrammatic representation of tillering in cereals.
(After Schindler.)

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

Tillering activity varies with the species, the individual,
and environmental conditions. In general, winter grains
tiller more than summer ones. It is dependent especially
upon the depth of seeding.. There seems to be an optimum
depth, which varies with the sort of grass. The average
depth of the tillering node in cereals is about 1 to 2 centi-

GRAMINEZ (POACEZ), GRASS FAMILY 75

meters. ‘Tillers are produced freely in moderately warm,
sandy soil. The number of tillers is also increased by
a large amount of reserve material in the seed, and by high
soil fertility, and by thin seeding. The effect of this last
factor is well shown in the following data taken from the
Nebraska Experiment Station Bulletin 127:

TILLERING oF OATS

Total number of stems

Pecks of seed sown per |
per acre

‘acre Stems per roo plants

4 466 1,419,000
8 279 1,732,000
16 ; 140 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 rhizomes are rhizomatous.

When the internodes of the rhizomes are very short, the
culms are close together, and the grass is known as a tufted
grass or as bunch grass, as in meadow fescue (Festuca pra-
tensis). Many of our most valued range grasses have the
bunch habit. When the internodes are long, the culms are
more widely separated, and a creeping grass, as awnless
brome grass (Bromus inermis), is the result.

Stoloniferous Grasses._When the horizontal stems are at
or above the surface of the ground, they are called runners or
stolons, as in buffalo grass (Buchloe dactyloides). Outside of
the grass family, the runners or stolons of strawberry are
very typical. Stolons are about as effective as rhizomes in
propagation. They usually produce a more open, loose tuft.
This is due to the long internodes. Stoloniferous grasses do
not produce as solid and uniform a turf as 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, 180° around the circumference. This arrange-
ment gives two vertical rows of leaves opposite each other
on the stem. Such an arrangement is said to be two-ranked,
distichous, or one-half spiral. We shall have occasion further
on to discuss other leaf arrangements, and to emphasize
the fact that leaves are developed on a stem in a definite
order.

The grass leaf in general appearance is unlike that of such
common plants as apple, cottonwood, maple and beet. In
these the leaf has a definite, narrow stalk or petiole and an
expanded blade (Fig. 159). The grass leaf is divided into
two distinct parts, sheath and blade (Fig. 26). The sheath
represents the leaf base, and forms a tube around the culm.
At the base of the leaf sheath, there is a distinct swelling.
The more or less flattened part of the leaf which spreads
away from the culm is the blade (lamina). The blades
are parallel-veined, that is, have many veins, about equal
in size, running parallel, and joined by inconspicuous vein-
lets. Parallel venation is characteristic of the leaves of
grasses, sedges, rushes, 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).

78 BOTANY OF CROP PLANTS

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

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

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

Auricle (Fig. 26) —This is a more or less pointed, thin,
ear-like structure projecting from the leaf edge at the junc-
tion of sheath and blade. It often clasps the stem but
may be-more or less twisted and bent away from it. It
varies greatly in size and shape. In the tribe Hordea,
the auricles are characteristic. They are entirely absent
in some species.

Inflorescence.—The grass inflorescence (flower cluster)
consists of a number of groups of flowers, each group being
called a spikelet. The spikelet is, in fact, the unit of the

GRAMINEE (POACE#), GRASS FAMILY 79

grass inflorescence. The spikelets are attached either
directly or indirectly to a main axis, the rachis (Fig. 28).

The three common sorts of grass inflorescences are the
spike, panicle, and raceme. When the rachis is unbranched,
so that the spikelets are not borne on individual stalks, but
are attached directly (sessile) to the rachis, the result is a
spike. The inflorescences of wheat,
barley, and rye are good examples of
spikes. Usually, each culm bears a
single spike. In the raceme, each spike-
let is borne on a short branch of the
rachis, as in sheep’s fescue (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- eat
sides the spike, raceme and panicle will Fic. 28 —Single spike-
be met with in some of the following ee eran pee
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 rachiilla, 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

80 BOTANY OF CROP PLANTS

spikelet with its parts removed in order. Each spikelet is
subtended by these two empty bracts. Following the sug-
gestion of Piper, we shall designate these two basal, empty
bracts as ‘‘glumes.”’ The lower of these is the “‘first glume,”
the upper the “second glume.” Above the two glumes, on
the rachilla, are one or more bracts; each one of these is
known as a lemma (flowering glume and inferior palea oi
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,

lemma,
pale.
\ SK f
\ Saad
grain
[7 I
If Yf |
Jad flower
~~srachilla

Ist flower Ist glume

~—-rachs

Fic. 29.—Spikelet of common wheat (Triticum estivum) 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

GRAMINEZ (POACEZ), GRASS FAMILY 81

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

Fic. 30.—Wheat flower with lemma removed; considerably magnified.

of the extreme sagittate nature of the latter, it appears
versatile. The ovary is one-celled, one-seeded, bears two
styles and two feathery stigmas.

There are many deviations from the typical form of spikelet. In Colean-
thus, the empty glumes are absent; in Nardus, solitary; in Homalocenchrus,
mere rudiments. In some Agrostis species, the palet is rudimentary. It is
not always two-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 Streptocheta 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, chasmogamous spikelets and
cleistogamous spikelets may occur in the same inflorescence.
According to Koernicke, two-rowed erect-eared barley
(Hordeum distichon erectum) bears only cleistogamous
flowers.

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

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

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

GRAMINE (POACEZ), GRASS FAMILY ~ 83

The grass fruit is called a grain or caryopsis. There is an
abundance of starchy endosperm. Sometimes the grain is
closely adherent to the palet and lemma, as in most barleys

and oats.

Phylogeny of Grasses.—The history
of the evolution of a group of organ-
isms is phylogeny. What is the origin
of the grasses? Are they primitive
forms, the progenitors of such closely
related groups as the lilies and other
common monocotyledonous plants; or
are they a reduced group? By those
who hold the latter view, which is
more widely accepted, grasses are con-
sidered to have come from lily-like
plants by a reduction and modification
of a number of parts of the flower.
Examination of the floral diagram of a
typical lily flower is shown in Fig. 31.
It has two sets of floral segments (which
together constitute the perianth) which
alternate, two whorls of stamens, three
in each whorl, and a pistil divided into
three chambers, hence tri-carpellary.
The stamens of one whorl alternate with
those in the other; those of the outer
whorl alternate with the inner segments

“of the perianth. The three carpels
alternate with the inner stamens. In
Fig. 31 is shown the floral diagram of
a grass flower with the rudimentary or

Q"

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

missing parts shaded. According to the view that grasses
are reduced lilies, there was a reduction in the lobes of

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 Streptocheta and Bambuse, 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
Bambusz); 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

GRAMINEA (POACE&), GRASS FAMILY 85

structure; the third, outer perianth whorl aborts. In this
connection it should be noted that the palet of einkorn
(Triticum monococcum) divides into two parts, at maturity,
on the median line, each half bearing a keel (Fig. 37).

According to the view presented above, the grass spike-
let is interpreted as a modified branch, bearing a number
of distichous bracts. The two lower bracts (glumes) are
sterile. The flowers occur in the axils of the lemmas. The
flower is of the lily type. The outer perianth whorl is rep-
resented by the palet, the inner by the lodicules; one whorl
(inner) of stamens (usually, not always) is aborted; the pistil
is three-carpelled. Hence, we see that grasses are derivates
of a normal monocot flower.

Grass-like Plants.—Grasses are closely related to the
sedges (Cyperacee). Sedges, however, have solid stems,
usually three-angled, leaves with closed sheaths, and the
fruit an achene. In the achene the pericarp or mature ovary
wall is not firmly grown to the seed coat which immediately
adjoins on its inner surface. The achene and the grain are
both dry, one-seeded fruits that do not split (dehisce) at
maturity, but in the grain the mature ovary wall is closely
adherent to the seed coat. In grasses, as pointed out on
page 77, the leaves are two-ranked or distichous. In
sedges, however, the leaves are three-ranked, or one-third
alternate. Sedges grow in wetter situations than grasses
and are often harsher in texture, due to the deposition of
silica in the stems and leaves. There are certain rushes
(Juncacee@), 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

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Univ. Nebr., 1906.

Warp, H. MarsHatt: Grasses, a Handbook for Use in the Field and
Laboratory. Cambridge, 1901.

TrvE, Ropney: On the Development of the Caryopsis. Bot. Gaz., 18:
212-226, 1893 (contains bibliography on development of grain).

GRAMINEZ (POACEZ), GRASS FAMILY 87

CEREALS

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

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

Key To Groups (GENERA) OF ImpoRTANT CEREALS!

1 What is a “key,” and how is it used? Throughout the following pages
there will be a number of “keys.” A “key” is a convenient form for dis-
tinguishing one plant from another, or one plant group from another. It
presents in concise form the principal differences between the plants con-
sidered. It also enables one to determine the proper classification of an
unknown plant. Most of the ‘‘keys” in the following pages are “artificial,”
that is, the characters used are obvious ones. The ‘‘keys”’ herein are con-
structed on the dichotomous plan, i.e. by twos. The entire number of groups
under consideration, whether these be species, genera, families, or higher
divisions, is first divided into two subgroups; each of the subgroups is sub-
divided into two groups, and so on. The alternatives are equally indented
on the page. In the key to the genera of cereals, they are first divided into
two large groups, the first including Zea, Oryza, Andropogon and Millets;
and the second, Avena, Secale, 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 . . 7 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, 7.¢., 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), Chetochloa, 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!

1This 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.

GRAMINEE (POACE), GRASS FAMILY 89

Collar without claw-like appendages, Oats (Avena sativa).
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 (Triticum spelta).
Collar and claws slender, Wheat (Triticum e@stivum).
Claws not hairy.
Collar and claws large and prominent.
Nerves of blades not prominent, upper surface rough, Barley (Hor-
deum sativum).
Nerves of blades broad and prominent, smooth on upper surface,
Polish wheat (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

Aaronsoan, A.: Uber die in Palastina und Syrien wildwachsend aufgefun-
denen Getreide-arten. Verhandl. K. K. Zool. Bot. Gesell. Wien.,
59: 385-590, 1909.

Contribution 4 histoire des cereales. Bul. Soc. Bot. (France), 1909.

ATTERBERG, 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: Uber 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.

Exxert, F.: Uber 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.

KorErnickE, F. and WERNER, H.: Handbuch des Getreidesbaues. I. Die
Arten und Varietéten des Getreides. II. Die Sorten und der Anbau
des Getreides. Berlin, 1885.

Uber die Entstehung und das Verhalten neuer Getreidevarietiten.
Archivs fiir Biontologie, 1908.

go BOTANY OF CROP PLANTS

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

Knissiinc, L.: Untersuchungen tiber die Keimung der Getreide. Landw.
Jahrb. (Bayern), 1:449-514, 1911.

KupeE1xa, F.: Uber die Entwicklung und den Bau der Frucht und Samen-
schale unserer Cerealien. Landw. Jahrb., 4: 461-478, 1875.

Hitrer, H.: Les cereales secondaires. Seigle, Mais, Sarasin, Millet, Rhiz.
Paris, 1910.

HorrmMan: Das Getreidekorn. Berlin, 1912.

Hont, T. F.: The Cereals of America. Orange Judd Co., New York, 1905.

Nowack1, A.: Anleitung zum Getreidebau, IV. Berlin, 1905.

Riwpau, 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.

Scumip, B.: Bau und Funktionen der Grannen unserer Getreide-arten. Bot.
Centralbl., 76, 1898.

Scumipt, O.: Uber den Entwicklungverlauf beim Getreide. Ein Beitrag
zur Sortenkenntnis. Landw. Jahrb., 45: 267-324, 1913.

Scuuiz, A.. Die Geschichte der kultivierten Getreide, I. Halle, 1913.
Scuuiz, B.: Wurzelatlas. Darstellung natiirlicher Wurzelbilder der Halm-
friichte in verschiedenen Stadien der Entwickelung. Berlin, 1911.
SEELHORST, V.: Versuche iiber die Méglichkeit einer Bewurzelung und
Adventivtriebbildung an oberirdischen Knoten von Getreidepflanzen.

Jour. Landw., 1902.

CHAPTER X
TRITICUM (Wheat)

Habit of Plant—Wheat isan 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 1 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 (énternodes), the sixth
being the spike-bearing one. The lowest joint usually re-

or

g2 BOTANY OF CROP PLANTS

mains short, sometimes less than 1 millimeter long; the second
joint also remains short; the sixth one is the longest.

Leaf.—The wheat leaf is of the ordinary grass type. The
blade varies considerably; the sheath is split; the ligule is
thin and transparent; the auricles are conspicuous, although
not as prominent as those in barley.

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

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

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

TRITICUM 93

sterile. In Fig. 28, the lemmas of four flowers are visible.
As a rule, but two grains mature. In some varieties, most
of the spikelets mature three grains, and less frequently
four.

The glumes are broad, varymg 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.

Fic. 32.—Opening of wheat flower. (Afler Hays.)

Opening of Flower and Pollination. Hays has shown (ina
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
g: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 spréad
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.

96 BOTANY OF CROP PLANTS

Embryo.—In the very young stage, prior to fertilization,
the axis of the ovule is parallel with that of the ovary. Soon
in its development, the ovule turns so that its micropyle is
directed downward (Fig. 33). At first, the young ovule
does not fill the ovary cavity, but soon does so by further
growth. The ovule is attached along its side to the ovary.
The groove indicates the position and extent of this at-
tachment. The first pair of seminal
(seed) rootlets appears in the embryo
about four weeks after 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.

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

Fic. 33.—Diagram- ‘
matic section of young Marked off, appearing first on the dorsal

ovary of wheat. (After side. According to Brenchley, starch

Bessey.) " F
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:

TRITICUM 97

1. Outer epidermis—one row of cells.

2. Parenchyma layer—many rows of colorless cells.

. Chlorophyll layer—one row of cubical cells, sometimes
two, and several in the groove region.

. Inner epidermis—one row of small cells.

. Outer integument—two layers.

. Inner integument—two layers.

. Nucellus—several layers of thin-walled parenchyma cells,
all bounded by a distinct nucellar epidermis.

w

Ir nN sf

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 per-
sist in the mature grain. The chlorophyll cells become longer,
lose their chlorophyll, and thicken their walls. In the proc-
ess of maturation, the ovary wall or pericarp becomes
firmly attached to the outer layer of the inner integument
of the ovule. This behavior seems to be well demonstrated
in all grasses investigated. The firm attachment of the peri-
carp to the ovule distinguishes the grain or caryopsis from
the achene. |

Ripening Stages.—It is customary to speak of four stages
in the ripening of the grain: (1) milk-ripe or green-ripe stage;
(2) yellow-ripe, gold-ripe, or ‘‘dough” stage; (3) full-ripe
stage, and (4) dead-ripe stage. ,

7

98 BOTANY OF CROP PLANTS

In the milk-ripe or green-ripe stage, the embryo is already
fully developed. The grain changes from pale green to dark
green in color, which change Nowacki explains as being due
to the resorption of several layers of the ovary wall, through
which the chlorophyll layer now shows. The endosperm cells
are filled with a watery sap in which are suspended a number
of starch grains; hence, when the grain is squeezed a white,
milky juice comes out.

In the yellow-ripe, gold-ripe, or ‘dough’ stage, the cells
of the ovary wall become thicker. The lumina of inner in-
tegument cells decrease in size, due to an increase in the
thickness of their walls. The color of the grain changes
from green to yellow, and the endosperm becomes tough and
waxy.

The full-ripe stage follows close upon the preceding. Asa
result of water loss, the different cell layers become dis-
torted. The grain becomes harder and firmer. Grain is
usually harvested while in this stage.

If the crop is now left in the field, the grain becomes brittle;
it is then said to be in the dead-ripe stage.

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

|
eran | “ph ‘a ioo grains,
Milk-ripe (a) July 9........ | 51.47 5.31 2.86
Milk-ripe (b) July 13........ 47.69 gery 3.58
34-37 5.07 4.44
Yellow-ripe July 20........ i 25.73 4.28 4-19
12.91 3.08 3.80
Full-ripe July 23........ 12.97 3-52 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. Forexample,
in the above experiment wheat collected in the dough stage
produced a plumule 9 inches long, in the full-ripe stage 10.1
inches long, and in the dead-ripestage 11incheslong. 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 roo 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

100 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-

Z D
Z
endosperm

Fic. 34—Common wheat (Triticum estivum). A, grain, groove side; B,
grain, embryo side; C, cross-section of grain through the embryo; D, cross-
section of grain beyond the embryo. :

: inner
—Sa ~“integument

——= ——nveellus

Fic. 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 IOI

Ovary wall or pericarp, of several cell layers.

. Testa, two layers of inner integument.
Nucellus.

Aleurone layer, outermost layer of endosperm.
Starchy endosperm.

Aker nm

Ovary Wail 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

102 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 P 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

| ; oer \ groove
starch
pai | a lindric
aleurone- ied
|
scutellum—\-—>— es scutellu
coleoptile-
hypocotyl —— an gr owing
Lge last-—— j of slem
P root——— -\_ i,
coleorhiza- x

Fic. 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

104 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 epiblast. Lying next to the endo-
sperm is a specialized structure, the scutellum, which is
attached to the hypocotyl. It has been suggested that the
scutellum and epiblast represent two cotyledons, one of
which (scutellum) is highly modified, the other (epiblast)
suppressed.

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

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

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

106 BOTANY OF CROP PLANTS

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

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

Relative Proportions of the Parts of the Grain.—
1. Bran (pericarp, testa, nucellus), 8 to 9 per cent.
2. Aleurone layer, 3 to 4 per cent.

3. Starchy or floury endosperm, 82 to 86 per cent.
4. Embryo or germ, about 6 per cent.

“Hard” and “Soft” Wheats.—A “hard”’ wheat is one with
a horny or flinty texture, and quite high in protein. Hard
wheats, as a result of their high gluten content, make a
“strong” flour, which is adapted for making light bread.
A “soft” wheat is more easily crushed than a hard wheat, has
a starchy or dull appearance, and is relatively rich in starch.
The “soft” wheats have been regarded with favor for the
making of bread and pastry flours. However, the flour from
soft wheats is said to be “‘ weak,” that is incapable of making
a large heavy loaf. At first there was much opposition to
hard wheats, because of difficulties in milling and baking.
In recent years, however, this opposition has been largely
overcome. ,

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

TRITICUM 107

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

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

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

108 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, 7.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 10g

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 108°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 60°F., three days at 50°F., and six days
at 40°F.

Three germinating stages in wheat are shown in Fig. 2.
The primary root is the first to appear. It ruptures the
coleorhiza which remains-as a collar about the root where it
breaks through the grain coats. Very soon two lateral roots
appear; hence the primary root system consists of a whorl
of three roots. The growing point elongates, the first 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:

I1IO BOTANY OF CROP PLANTS

REPEATED GERMINATION

Per cent. germinated
Kind of seed
Ist 2d 3d 4th sth 6th
Schumacher wheat.....' 100 100 90 | 87 67 8
Clawson wheat........ 100 100 97 98 84 38
Buckwheat............ 100 100 100 98 65 39

Classification of the Types of Wheat.—Hackel divides the
genus Triticum into two sections, Aegilops and Sitopyros.
In the first, the glumes are flat or rounded on the back; in
the second, keeled. TJ. 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.

Fic. 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. TJ. monococcum (einkorn).

TRITICUM IIl

Spikelets more than two-flowered, two or more fertile; terminal spikelet
developed; lateral teeth of glumes obtuse; palet remaining entire at
maturity.

Glumes as long or usually longer than lemma; palet about two-thirds
as long as lemma. T. polonicum (Polish wheat).
Glumes shorter than lemma; palet nearly as long as lemma.

Rachis brittle, articulated, breaking at nodes when threshed, the seg-
ments remaining attached to spikelets; spikelets two-grained (some-
times three in spelt).

Spikelets not set thickly on stem; arched on inner side; adhering por-
tion of rachis thick, blunt; stem above with central canal. T.
spelta (spelt).

Spikelets set thickly on stem; flattened on inner side; adhering portion
of rachis slender, pointed; stem above, with exception of narrow
canal, filled with pith. TJ. 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. turgidum
(Poulard wheat).

Empty glumes keeled in upper half; rounded below (sometimes
slightly keeled in lower half); lemma sometimes bearded.

Spikes very short (rarely over 2 inches); very compact or crowded;
thicker at apex than center or base; grains small, short. T.
compactum (club wheat).

Spikes longer than 2 inches, open; sides usually parallel or nearly
so. T. a@stivum (common bread wheat).

The types of wheat fall into two natural groups, as to
attachment of lemma and palet to grain, as follows:

1. “‘ Naked wheats,” in which the grain comes free from the
lemma and palet, and the rachis is tenacious (T. durum,
turgidum, compactum, @estivum, and polonicum).

2. “Spelt wheats,” in which the grain remains attached
to the lemma and palet, and the rachis is fragile (T. mono-
coccum, dicoccum, and spelia).

II2 BOTANY OF CROP PLANTS

Beyerinck has succeeded in producing crosses of einkorn
with dicoccum, none of which were fertile, however. Aaron-
sohn says that 7. polonicum hybridizes with the other species,
T. estiveum 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,

Fic. 38.—Spikes of the types of wheat. 1, Polish wheat (Triticum polo-
nicum); 2, club wheat (T. compactum) ; 3, common bread wheat (T. estivum);
4, Poulard wheat (T. turgidum); 5, durum wheat (T. durum); 6, spelt (T.
spelta); 7, emmer (T. dicoccum); 8, einkorn (T. monococcum).

and Switzerland. Grains in the ear have been found in the remains near the
homes of Swiss lake-dwellers of the Stone Age. It is a native of Asia Minor.
Triticum a@gilopoides is considered to be the wild form of our cultivated ein-
korn. This wild species is divided into the two subspecies: T. thaoudar and
T. boeoticum. In the first, only the lower flower is fertile, as a rule, but both
bear awns, while in boeoticum 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. egilopoides differs from cultivated forms of
einkorn in that its spikes are more fragile, and the grains smaller and lighter
in color.

TRITICUM 113

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

T. spelta (spelt) is the oldest grain cultivated in Greece, Egypt, and the
Roman Empire. It is of slight economic importance in the United States.

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

T. durum (durum) varieties are also known as ‘‘goose,’’ ‘wild goose,”
and “macaroni” wheats. They are hard wheats, particularly adapted
to the arid regions, where they are better yielders than @estivwm wheats.

AF)
ww be

&
elie Sat ny Dd ae

Fic. 39.—Spikelets of the types of wheat. 1, einkorn (Triticum monococ-
cum); 2, spelt (T. spelta); 3, emmer (T. dicoccum); 4, common bread wheat
(T. zstivum); 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. turgidum (Poulard wheat) is of little consequence in this country. The
spikes are quadrangular or rectangular in cross-section. There is a tendency
to form branching spikes, as in Alaskan and Seven-headed or Egyptian
varieties. Such varieties also go under such common names as Stoner,
Miracle, Eldorado, Jerusalem, Many-headed, Many-spiked, Wild Goose, etc.

8

II4 BOTANY OF CROP PLANTS

T. compactum (club wheat) varieties are said to be adapted to the
Pacific Coast and Rocky Mountain States. In club wheats, the spikes
are only two or three times as long as broad, and typically broader
at the top than at the base, thus appearing somewhat club-shaped. The
joints of the rachis are very short, so that the spikelets are crowded and often
stand outright.

T. estivum (common wheat).—The bread wheats of the world are largely
varieties of estivum.

Origin of Wheat—A few years ago, Aaronsohn brought
from Syria a wild emmer which was named by Koernicke
Triticum dicoccum dicoccoides (T. hermonis Cook) (Fig.
40). Later, in an expedition in Upper 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 climates,

TRITICUM

Fic. 40.—Wild emmer of Palestine (Triticum dicoccum dicoccoides), grown

(Cook, U. S. Dept. of Agr.)

in experimental plat at Bard, California.

116 BOTANY OF CROP PLANTS

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

In the wild wheat of Palestine, the kernels
are normally retained by the spikelet. It
differs also from domesticated wheat in the
order of maturity of the spikelets. In do-
mesticated wheat, the first spikelets to de-
velop flowers are those near the middle of
the head, while in the primitive wheat the
terminal spikelets are the first ones. Primi-
tive wheat also shows some indications of
sexual dimorphism. Some plants have been
observed to bear protogynous, others pro-
tandrous, flowers. The spikelets of this wild
form never mature more than two grains
(Fig. 41), and those of the same spikelet are
unequal in size. The smaller grain is borne
by the lower flower in the spikelet; this
flower has the longer awn too.

A. Schulz thinks that many, but not all, of the primi-
tive wheat individuals found by Aaronsohn are hybrids
between T. egilopoides thaoudar and dicoccoides. The

Fic. 41.—Spike- origin of the different types of cultivated wheats, as
let of wild emmer given by Schulz, is shown in the following:

apres 1. Einkorn series, of which T. egilopoides is the
x 244. * prototype.

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

Spelta, compactum, estivum, and capitatum.

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

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-REQUIREMENT DETERMINATIONS AT AKRON, COLORADO, 1911, 1912,
AND 1913, BASED ON THE PRODUCTION OF Dry MatTTER

Plant Mean of genus
PLOSO: fsjiscnd scces Weeks eee Daido 293
MANGE scis es crac Anchen B48 wd Pathe oe 310
SOP EDUTE is Seorig: x sear n arartiak wiesnttins 322
CORN Sac siais ais ts Anti 2 es eS 3608
Whedticcevres solepiaysaina oithdes 513
Barleyeen sien 4a nyer ss aes es 534
Buckwheat...............0200.0. 578
OBS isedeeit)e Accisna cS Stsuanis Basew aineaates 507
Ry Es adlilsadawsaliins a we pees 685
Beet; :sgaliscg irc: cae sna 397
PotatOye ces vonae gtieted eras ene 636
Pea, Canada field............... 788
AULA fas. oie enact ena ten ee 2 aaa Hp 831

If the water requirement of proso millet is regarded as 1,
the water requirement for the following crops is as follows:
millet 1.06; sorghum 1.10; corn, 1.26; wheat 1.76; barley
1283; Oats 2.045 Tye, 2.345 Fick, 2.42.

The water requirement of a plant is dependent upon a
number of conditions, chief of which is the fertility of the
soil. The water requirement is greater in an unfertile than

118 BOTANY OF CROP PLANTS

in a fertile soil. The application of fertilizers may increase
the total amount of water taken in by the plant, due to
increased plant growth, but the requirement per unit of
dry matter is lowered.

The effect of climate and soil on the composition ‘of the
grain has been discussed.

Uses of Wheat.—By far the largest proportion of the
world’s supply of flour is made from wheat. As already
stated, the hard wheats, particularly durum varieties, are
used extensively in the manufacture of macaroni and allied
products. In the manufacture of macaroni, the wheat is
first ground into a course product known as “‘semolina.”

Fic. 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, 1915

i

State Acres | Bushels ao ee

Serer rare! a 7 so 3 Boy eee =
North Dakota...... 8,350,000 | 151,970,000 132,214,000
Kansasi-. 220 e iene 8,525,000 | 106,538,000 94,819,000
Minnesota......... 4,310,000, 73,420,000 66,678,000
Nebraska.......... 3,947,000 | 72,154,000 60,609,000
South Dakota...... 3,725,000: 60,762,000! 54,835,000
Illinois............ 2,800,000 53,200,000 53,200,000
Washington........ 2,000,000 50,394,000, 41,328,000
Indiana........... 2,750,000! 47,300,000 | 48,246,000
OHIO: acoeacna see 1,980,000 40,194,000 41,802,000
All other States... . 21,511,000 , 352,573,000 336,575,000
United States...... 59,898,000 T,O11,505,000 930,302,000

References

AARONSOBN, A., and SCHWEINFURTH, G.: Die Auffindung des wilden Em-
mers (Triticum dicoccum) in Nord Palastina. Altneuland Monatsschr.
fiir die wirtschaftliche Erschliessung Palastinas, Berlin, Nos. 7-8, 213-
220, 1906.

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TRITICUM 121

AARONSOHN, Aaron: Agricultural and Botanical Exploration in Palestine:
Wild Prototypes of Wheat and Other Cereals in Palestine. U.S. Dept.
Agr. Bur. Plant Ind. Bull. 180: 36-52, 1910.

BEIJERINCK, M. W.: Uber den Weizenbastard Triticum monococcum $?
Triticum dicoccum @. 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: roo-114, 1894.

BiLoomFiELpD, L. M.: Contributions to the Life History of the Wheat Plant
(T. vulgare). Ann. Rep. Ohio State Acad. Sci., 2: 12-14, 1894.

BRENCHLEY, W. E.: On the Strength and Development of the Grain of Wheat
(T. vulgare). Ann. Bot., 23: 117-139, 1909.

BRENCHLEY, W. E., and Hatt, A. D.: The Development of the Grain of
Wheat. Jour. Agr. Sci., 3: 195-217, 1909.

Cuopat, R.: A Grain of Wheat. Pop. Sci. Mo., 82: 33-46, 1913.

Coss, 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.

Donp.incER, P. T.: The Book of Wheat. Orange Judd Co., 1908.

Eriksson, J.: Beitrage zur Systematik des cultivierten Weizens. Landw.
Versuchsstat., 45: 37-135, 1804.

FruwirtH, C.: Das Bltthen von Weizen und Hafer. Deut. Landw. Presse,
32: 737-739) 747-748, 1905.

Hays, WiLLeEt 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.

Konpvo, 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.

Mostius, F.: Untersuchungen iiber die Sorteneinteilung bei Triticum vul-
gare. Inaug. Diss., Giessen, 1913. Druck von F. Stollberg, Merseburg.

OspornE, T. B.: The Protein of Wheat Kernel. Carnegie Inst. Washington
Pub. 84: 1-119, 1907.

Scuutz, Aucust: Abstammung und Heimat des Weizens. 39 Jahrsber.
Westfal. Prov. Ver. Wiss. u. Kunst (zu Miinster) fiir 1910-1911, S.
147-152, IQII.

Die Geschichte des Weizens. Ztschr. Naturw., 83: 1-68, 1911.
Die Abstammung des Weizens. Mitt. Naturf. Gesell. Halle, 1: 14-17,
1912.

Ecxrrson, Soputa 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.
Halle, 2: 17-20, 1913.
ScoFIELD, Cart S.: The Algerian Durum Wheats: A classified list, with
U.S. Dept. Agr. Bur. Plant Ind. Bull. 7: 1-48, 1902.
Kans. Agr. Exp. Sta. Bull. 127:

Mitt. Naturf. Gesell.

descriptions.
Tren Eycx, A. M.: The Roots of Plants.

199-252, 1904.
THATCHER, R. W.: The Progressive Development of the Wheat Kernel.

Jour. Amer. Soc. Agron., 5: 203-213, 1913.
Woops, CHartes, and Merritt, L. H.: Entire Wheat Flour.

Exp. Sta. Bull. 103: 61-80, 1904.

Me. Agr.

CHAPTER Xl
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. f
Inflorescence.—The spikelets of oats are arranged in a

panicle. The branching on the main axis is racemose, that

| 1A

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

of a higher order is cymose (Fig. 44). The numbér of
whorls in a panicle ranges from four to nine, mostly five or
six. Apparently, there are a number of primary branches
arising ata 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 sativa),

Q B

Fic. 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: (1) Panicle stiff and upright,
(2) panicle pyramidal, the branches long, slender, and rising

126 BOTANY OF CROP PLANTS

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

The number of spikelets in a panicle varies, an average
number being near 75. The rachis is straight or only slightly
undulating. A single spikelet is borne at the end of a slender
pedicel, which varies in length.

Spikelet and Flower (Fig. 46)—The number of flowers in
an oat spikelet varies from two to five, rarely it is one.
Three, however, is the usual number. In the so-called “‘ single

pslerile 3rd flower
Z

<——Ist glume

Fic. 46.—Spikelet of panicle oats (Avena sativa). x als.

oats,” but one flower, the basal, matures. In “twin oats,”
two flowers mature. Three kernels occasionally mature.
The upper flowers of the spikelet are often staminate or
imperfect. If a large number of spikelets bear three kernels,
there is usually a reduction in the number of spikelets inthe
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. Asa 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 /fowers to open
in the panicle are in the middle siisiaa, ke 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
2:00 to 4:00p.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 quality 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 OF CROP PLANTS

The percentage of hull in the upper grains of a spikelet is
less than that of lower grains. It is also stated that early-
ripening sorts have a greater percentage of hull than late-
ripening ones. The reports are conflicting concerning the
percentage of hull in short plump grains and in long slender

chy

endosperm

Fic. 47.—A, mature grain of wild oats (Avena 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, BandC, x5; D, X10.

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. Thesecond 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: (1) 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. brevis (short oats), A. byzan-
tina (Mediterranean oats) and A. 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. fatwa has lost the fragility of
its articulations, its hairs and, in some instances, its awns.
A. strigosa and A. brevis are derived from A. barbata, a
species growing wild in the Mediterranean region, Persia,
Mesopotamia, west to Atlantic Europe and Great Britain.
A. abyssinica is originated from A. wiestii, a species in-
digenous to North Africa and Arabia. A. byzantina has
come from A. séerilis, 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. fatwa 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 rgr5.

LEADING COUNTRIES IN THE PRODUCTION OF OATS, SHOWING ACREAGE AND
PRODUCTION, 1915

Countries Acres | Bushels
United Statesic.. 4. gues Meurer, Meee 40,780,000 ,! 1,540,362,000
Russia, European................... 44,787,000 1,006,983,000
GerMa nyse p22 see AI aaa laid Faia ivais tues . 650,000,000
Canad aid: ceicwiacind< pian te tha dns 11,365,000 481,035,000
Brances iain ois genie c ties eee Be 9,051,000 234,924,000
Austria-Hungary.................... Nyeais brung ae 234,924,000
United Kingdom.................... 4,149,000 195,169,000
Swed ensiieidscckcuiteneaspecasee nhs Seen aca 70,000,000
ATPENUMA i .cc- cola dete eens sanieteeetes 2,869,000 62,392,000

* No official statistics.

AVENA 133

THE PRODUCTION OF OaATs IN THE UNITED STATES, 1915

States ; Acres Bushels | a ae
1 i}
VO Wabig dest cacion & asccs 4,950,000 198,000,000 63,360,000
Mllinois............ 45,343,000 195,435,000 68,402,000
Minnesota........ 3,125,000 134,375,000 43,000,000
Wisconsin......... 2,150,000! 99,975,000 35,991,000
North Dakota.. .. 2,450,000 | 98,000,000 26,460,000
South Dakota ..... 1,725,000! 72,450,000 20,286,000
Nebraska.......... 2,200,000 70,400,000 21,824,000
ONO 44a wa aens 1,683,000 69,063,000 24,841,000
Indiana........... | 1,638,000 65,520,000 22,277,000
Michigan........ : 1,530,000 64,260,000 22,490,000
All other States... . 14,986,000 472,944,000 | 206,638,000
- |
United States...... 40,780,000 | 1,540,362,000 ‘555,569,000
References

ATTERBERG, A.: Neues System der Hafervarietiten nebst Beschreibung der
nordischen Haferformen. Landw. Vers. Stat., 39: 171-204, 1881.

Boumer, C.: Uber die Systematik der Hafersorten sowie iiber einige zuch-
terisch wichtige Eigenschaften der Haferispe. Berlin, 1909, P. Parey.
Hafer im Bilde. Fiihling’s Landw. Ztg., 609-616, 1911.

Broii, J.. Beitrage zur Hafer Morphologie. 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. ro:
329-364, 1900.

CrippLE, 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: 1-11, 1912.

DENAIFFE AND Srropor: L’avoine, etc. Paris, 1902, 210 figures, pp. 848.

Fruwitn, C.: Die Haferrispe bei der Beurteilung der Sorten und in der
Ziichtung. Fiihling’s Landw. Ztg., S. 289, 1907.

HaseEtHorr, E.: Vergleichende Untersuchungen deutscher und amerikanis-
cher Haferkorner. Landw. Vers. Stat., 65: 339-349, 1907.

134 BOTANY OF CROP PLANTS

Haussxnecut, E.: Uber die Abstammung des Saathafers. Mitt. Thiiring.
Bot. Ver. N. F. Heft, 2: 45-49, 1892.

Raum, H.: Zur Systematisierung der Hafersorten. Fihling’s Landw. Ztg.,
58: 496-501, 1909.

Rimpau, W.: Die genetische Entwicklung der verschiedenen Formen unserer
Saatgerste. Landw. Jahrb., 21: 699-702, 1892.

Scuuz, 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: 6-11, 1914.

TANNERT, PauL: Entwickelung und Bau von Bliite und Frucht von Avena
sativa L. Inaug. Diss. Zurich, 1905.

THELLUNG, A.: Uber die Abstammung, den systematischen Wert und die
Kulturgeschichte der Saathafer-Arten (Avena sative Coss.) Vrtljschr.
Naturf. Gesell. Zurich, 56: 293-350, 1911.

Trasvr, L.: Origin of Cultivated Oats. (Translation) Jour. Hered., 5: 74-85,

* IQS.
Contribution a l’etude de l’origine des avoines cultivees. Compt. Rend.,
149: 227-229, 19009.

VIERHAPPER, F.: Zur Systematik der Gattung Avena. Verhandl. K. K.
Zool. Bot. Gesell. Wein., 56: 369-370, 1906.

Zave: Die Zwischenformen von Flughafer (Avena fatua) und Kulturhafer
(Avena sativa). Fiihling’s Landw. Ztg., 369-384, 1912.

CHAPTER NII
HORDEUM (Barley)

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

The root system of barley resem-
bles that of oats. The culm has
from five to seven joints, sometimes
eight, the length of which increases
from below upward. Barley does
not tiller as abundantly as oats and
winter wheat. The leaves resemble Eee an, wachises Oe

three common _ cereals.
those of wheat. The auricles, how- A, barley; B, wheat; C,
ever, are usually very much pro- "* **
nounced, and may be used as a basis of distinction between
the straws (Fig. 26).

Inflorescence.—The inflorescence is a cylindrical “spike,
the shape of which varies slightly in the different barley

135

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.

Fic. 49.—A, triplet of spikelets of six-rowed barley (Hordeum vulgare
hexastichon); note. that there are three fertile spikelets at the rachis joint;
B, triplet of spikelets of two-rowed barley (H. distichon); the two lateral
spikelets are sterile; C, single spikelet of hooded barley (H. vulgare tri-

furcatum).

At each joint of the rachis, there are three spikelets, each
one-flowered (Figs. 49 and 50). The lateral spikelets of each
triplet are sometimes imperfect, as in two-rowed barley.
Each spikelet is on a short branch or rachilla, which is pro-
duced beyond the flower and appears as a bristle (Fig. 51)
lying within the groove of the grain. As in wheat, there is

HORDEUM 137

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

Spikelet and Flower.—Each spikelet is one-flowered. The
glumes are narrow and awn-like, forming an apparent in-

Fic. 50.—1, triplet of spikelets of six-rowed barley (Hordeum vulgare
hexastichon); 2, of hooded barley (H. vulgare trifurcatum); 3, of medium

barley (H. vulgare intermedium); 4, of two-rowed barley (H. distichon). Nat.
size.

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

138 BOTANY OF CROP PLANTS

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

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

Fic. 51.—A, barley grain with the bloom with open glumes,
Bacee B. with “bull” removed; C, 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

HORDEUM 139

weak to force the glumes apart. In four-rowed barley,
in which open flowers are the rule, lodicules are well
developed. It would seem, then, that in four-rowed
barley and two-rowed nodding barley, there is a possi-
bility of cross-pollination, while in six-rowed, peacock,
and two-rowed erect barleys this possibility is excluded.
However, very few positive cases of natural hybridization
of barleys have been observed. The reason for this prob-
ably is that the styles are short and do not protrude beyond
the glumes. Rimpau examined a large number of sorts, and
in all, found but eight sure cases of crossing, and these were in
four-rowed barleys. Self-pollination is the 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:oo a.m. Very little blooming
occurs in the middle of the day. There is a slight amount
between 3 and 5 o’clock in the afternoon, but by 8 in the
evening all blooming has ceased.

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

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

I40 BOTANY OF CROP PLANTS

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

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

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

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

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

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

3. Testa, two layers of inner integument.

4. Nucellus, one row of cells.

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

6. Starchy endosperm.

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

HORDEUM I4i

The embryo of barley is very similar to that of wheat.
It occupies but a small part of the grain. Five to eight
secondary rootlets occur. The epiblast is absent in the genus
Hordeum. “The endosperm varies from mealy to glassy or
translucent. Mealiness is the result of a high percentage of
starch, while translucency indicates a high percentage of
protein. The relative amounts of starch and protein in the
different types vary. The two-rowed barleys are used almost
exclusively in brewing.

There is no gluten in barley grains, and for this reason
light bread cannot be made from the flour.

Color of Grain.—Harlan has made a study of the color of
barley grains. He says: ‘‘There are two coloring materials
in barley: One, anthocyanin, is red in its acid and blue in
its alkaline condition; the other, a melanin-like compound,
is black. The pigments may occur in the hulls, the peri-
carp, the aleurone layer, and occasionally in the starch endo-
sperm. The resulting colors of the grain are quite compli-
cated. White denotes the absence of all pigment; a heavy
deposit of the melanin-like compound in the hulls results in
black; a light deposit, brown. Anthocyanin in the hulls re-
sults in a light violet-red. In naked forms the melanin-
like compound in the pericarp results in a black kernel;
anthocyanin produces a violet one. The acid condition of
anthocyanin in the pericarp superimposed upon the alkaline
condition in the aleurone layer gives the 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

I42 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 efficiency
in a well-matured, well-cured grain.” As has been indicated,
the principal enzyme secreted by the germinating embryo
is diastase. It has the specific property of changing starch
tosugar. 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

N
(13.2 =<) @ a
“7 \
i (, \
8 e = 508 a 8
u fe
X oo. Y)
( \s Ei, } .
en x? \ cE)!
SS |G @ | @,
A }
( ®
~
*
* rh
Y/
3 O
Cc

Fic. 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 ‘‘acrospire” is sometimes applied
to these leaves.

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

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

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

HORDEUM 145

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

A form of four-rowed barley, Hordeum vulgare pallidum,
is the common barley in northern Europe, Asia, and America.
There are both winter and summer forms. Hordeum vulgare
trifurcatum is the four-rowed Nepal barley. In this, the
lemmas each have three pronged awns which bend back in
the form of small horns or hoods (Fig. 49). It is also often
called “hooded barley.”” There are both naked and hulled
hooded barleys. Hordeum vulgare coerulescens is blue barley,
H. vulgare nigrum, black barley, and H. vulgare coeleste, the
hull-less Jerusalem barley.

Hordeum vulgare intermedium (medium or hybrid barley).—
Under this name are included those barleys that are transition
forms between the two- and many-rowed types (Fig. 52). In
these intermediate forms, only the two middle rows are nor-
mally formed, the four lateral ones being beardless and smaller.
It is quite probable that the zntermedium forms are segregates
of the hybrids of certain two-rowed and many-rowed forms.

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

There are four rather common types of two-rowed barleys:
10

146 BOTANY OF CROP PLANTS

1. Hordeum dislichon zeocriton (peacock or fan barley)
(Fig. 53).—The spikes are very dense and short, about 6

Fic. 53.—Spikes of barleys. 1, two-rowed nodding barley (Hordeum dis-
tichon nutans); z, medium barley (H. vulgare intermedium); 3, four-rowed
barley (H. vulgare pallidum); 4, hooded barley (H. vulgare trifurcatum); 5,
six-rowed barley (H. vulgare hexastichon).

centimeters long, broad at the base and narrow at the tip,
and with widely spreading beards. :
2. Hordeum distichon nudum (two-rowed naked barley).

HORDEUM 147

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.

A 3

NI

Fic. 54.—Bases of the grains of two-rowed barleys. A, B, nodding barley
(Hordeum distichon nutans); C, D, erect-eared barley (H. distichon erec-
tum). (After Newman.)

4. Hordeum distichon nutans (bent or nodding barley).—
In this the heads hang down when ripe. On the dorsal side
of the grain at the base, there is a slight horseshoe-shaped
depression. In lengthwise section, the base of the kernel
slopes off (Fig. 54). Rachis joints are 2.8 to 3.5 millimeters

148 BOTANY OF CROP PLANTS

Jong. The rachilla is broom-form or very hairy. The noted
malt barley, Chevalier, belongs to this type.

Origin of Cultivated Barleys——There are two principal
opinions regarding the origin of cultivated barley, that of
Koernicke and that of Rimpau. Koernicke considers Hor-
deum spontaneum to be the prototype of all our cultural
forms. This wild barley is nearest related to the nutans
form of two-rowed barley, being distinguished from the
latter by its more fragile rachis, less compressed spike,
stronger awns, larger side spikelets, perennial habit, and its
stronger tendency to tiller. The variety 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 six-rowed
barleys.

Rimpau, on the other hand, considers the six-rowed
bearded barley as the prototype of all other barley types.
Through a process in which side spikelets become rudimen-
tary, there arose the various four- and two-rowed types.
Rimpau bases his opinion on the nature of the offspring
between zeocriton and trifurcatum.

Environmental Relations.— Winter barleys are less resist-
ant to winter cold than either winter wheat or winter rye.
Consequently, in the Northern States practically all barley
is spring-sown. As a spring-sown crop it has a wide geo-
graphical range. It is grown as far as 65° N. latitude in
Alaska, and to an altitude of 7,500 feet in the Rocky Moun-
tains. At higher elevations it is grown as a hay, the chief
variety being ‘“‘bald barley.” Barley also does well in
southern California.

HORDEUM 149

Barley stands between oats and wheat in its water
requirement.

Uses of Barley.—Barley has a great variety of uses. Its
greatest use is in the preparation of malt. The two-rowed
barleys have larger and softer grains than six-rowed barleys
and therefore are preferred for malting purposes. Smaller
quantities are ground into flour from which bread is made.
“Pearl barley”’ (grains with the lemma and palet removed) is
used for soups. Barley enters into a few cereal breakfast
foods. It is a valuable stock feed, especially for hogs, sheep,
dairy cows, and poultry. The six-rowed barleys are regarded
as valuable sorts for feeding. The hooded varieties, chiefly,
are grown as hay. Barley is sometimes grown as a pasture
crop, as a nurse crop and as a smother crop. A pasture crop is
used for grazing. A nurse crop is a temporary one often
planted with a forage plant such as clover or alfalfa in order
to secure a greater return from the land the first year, also to
inhibit weed growth, and to prevent the blowing or washing
of the soil. A smother crop is used to prevent the growth of
weeds. The straw of barley is fed, and also serves as a bed-
ding for stock. Malt sprouts and “ brewers’ grains” are now
and then utilized as stock food.

The Brewing Process.—Brewing operations vary con-
siderably in the different countries, and with the character of
the product. The brewing materials employed are malt,
hops and water. The malt is made from germinating barley,
and to this are sometimes added unmalted cereals such as
corn, wheat and rice.

Malting.—In this process, barley is prepared for brewing
purposes. The barley grains are steeped for about forty-
eight hours in water, and then spread out on the malting
floor. The temperature of the air in the malting room is
between 50 and 60°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 ret

ACREAGE, PRODUCTION AND FARM VALUE OF BARLEY IN VARIOUS
STATES, 1915

States Acres | Bushels seats yeine, Dees
North Dakota...... 1,400,000 44,800,000 19,712,000
Minnesota..... . #3 1,350,000 | 41,175,000 | 20,176,000
California......... 1,360,000 30,440,000 24,453,000
South Dakota... .. 750,000 | 24,000,000 | 11,040,000
Wisconsin. ..... a 656,000 23,288,000 13,041,000
TOWariéiae og ages 353,000 — 10,943,000 5,362,000
Kansas............ 270,000, 8,370,000 3,515,000
All other States... 1,256,000 44,993,000, 25,200,000
United States...... 7,395,000 | 237,009,000 122,499,000
References

ATTERBERG, A.: Die Erkennung der Haupt-varietiten 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.

Brot, J.: Uber die Unterscheidung der zweizeiligen Gerste-Hordeum
distichum-am Korne. Inaug. Diss. Univ. Jena, 1906.

Das Gernstenkorn im Bilde. Stuttgart, 1908.

Brown, H. T., and Escomsez, F.: On the Depletion of the Endosperm of
Hordeum Vulgare during Germination. Proc. Roy. Soc. (London),
63: 3-25, 1898.

Fruwirta, C.: Das Bliihen der Gerste. Fiihling’s Landw. Ztg., S. 544, 1906

Haran, 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.

Henninc, E.: Beobachtungen tiber das Bliihen der Gerste (Schwedisch).
Bot. Notiser., 1905.

Hume, A.: Die botanischen Unterscheidungsmerkmale bei zweizeiliger
Gerste. Illus. Landw. Ztg., 830-839, 1909.

JouannsEN, W,: Entwickelung und Konstitution des Endosperms der
Gerste. Ztschr. Gesam. Brauw., 1905.

Kraus, C.: Die Gliederung des Gersten- und Haferhalmes und deren Bezie-
hungen zu den Fruchtstainden. Beiheft I der Naturwis. Ztsch. fiir
Land- und Forstwirthschaft. Miinchen, 1905.

152 BOTANY OF CROP PLANTS

Mann, ALBERT, and Hartan, H. V.: Morphology of the Barley Grain with
Reference to its Enzyme-secreting Areas. U.S. Dept. Agr. Bull. 183:
1-32, 1915.

QuantTeE, Huco: Die Gerste, ihre botanischen und brautechnischen Eigen-
schaften und ihre Anbau. Berlin, 1913.

Rimpav, W.: Die genetische Entwicklung der verschiedenen Formen unserer
Saatgerste. Landw. Jahrb., 21: 699-702, 1892.

Scuuiz, A.. Die Geschichte der Saatgerste. Ztschr. Naturw., 83: 197-233,
1912.

Die Abstammung der Saatgerste, Hordeum sativum I-II. Mott. Naturf.
Gesell. Halle, 1: 18-27, 1912.

TscHERMAK, E.. Die Bliih- und Fruchtbarkeitsverhdltnisse 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.

Zos1, A., and Mixoscu, C.: Die Funktion der Grannen der Gerstenahre,
Zitzber. Akad. Wiss. (Vienna) Math. Naturw. KI., ror: Abt. 1, 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

. 153

154 BOTANY OF CROP PLANTS

small, membranous, and ciliate on the upper margins. There
are three stamens, and a single pistil with two feathery
stigmas.

Opening of the Flower, Pollination and Fertilization.
Rye is the only common cereal, besides corn, that is regularly
cross-fertilized. These two cereals cannot be self-fertilized
without a reduction in vigor and productivity. Apparently,

Fic. 55.—Rye (Secale cereale). A, a single spikelet at a joint on the
rachis; B, grain, external view; C, grain in cross-section. A,X 234; BandC,

x 5.

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 11:00a.m. Then
blooming decreases throughout the afternoon, becoming

SECALE CEREALE 155

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

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

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

Rye protein usually forms about 6 to 12 per cent. of the
grain. Gluten is present in the protein, hence, the flour may
be made into porous bread. It will be recalled at this point
that of the common small cereals, wheat and rye possess glu-
ten, while oats and barley do not. The flour from rye is
more starchy than that from wheat.

Germination of Rye.—Under favorable conditions, germi-
nation will take place in thirty-six to forty-eight hours. The
optimum germinating temperature is 77°F., maximum 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 in the
manufacture of paper, strawboard, hats, and other coarse
straw articles.

Production of Rye.—Russia produced 861,097,000 bushels
of rye in 1915; Germany ranked second, with 470,000,000
bushels, Austria-Hungary third, with 154,075,000 bushels,
and the United States fourth, with 49,190,000 bushels.
The five leading States in the order of their production for
the year 1915 are Wisconsin, Michigan, Minnesota, Pennsyl-
vania, and Nebraska.

References

Batatin, A.: Das Perennieren des Roggehs. 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.
Scuutz, Aucust.: Die Geschichte des Roggens. Jahresbericht des West-
falischen Provinzial-Vereins fiir Wissenschaft und Kunst (zu Miinster)
fiir 1910-1911, 39:153-163, Ig1I.
Beitrage zur Kenntnis der kultivierten Getreide und ihrer Geschichte, I.
Die Abstammung des Roggens. Zeitschr. Naturw., 84: 339-347, 1913.
TscuerMaK, E.: Uber kiinstliche Auslosung des Bliihen beim Roggen.
Ber. Deut. Bot. Gesell., 22: 445-449, 1904.
Das Blihen des Roggens (Secale cereale). Ostrk. Landw. Wchnbl.,
1906, p. 163.
Die Bliih- und Irruchtbarkeitverhdltnisse bei Roggen und Gerste und das
Auftreten von Mutterhorn. Fuhlings Landw. Ztg., 55:194-199, 1906.
Uricu, C.: Die Bestéubung und Befruchtung des Roggens. Inaug. Diss.,
Jena, 1902.
Witrmack, L.: Uber die Stammpflanze des gemeinen Roggens, Secale
cereale. Verhandl. Bot. Ver. Brand., 32: 32-34, 1890.

CHAPTER XIV
ZEA (Corn, 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 1 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 (6) 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 Ine

| ground Ine

a
| =p
7

\\

4

\
=
{
\

ETAT Pre
1 Hi, tle lice, ee om, col | |

Fic. 56.—A, root system of corn (Zea mays); the squares are one foot on a

side; B, prop or aerial roots of corn. (A, redrawn from U. S. Dept. Agri.; B,
somewhat modified after Bailey.)

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

ZEA 159

This is quite likely a response to oxygen supply, as well as to
moisture supply. The amount of oxygen in the soil decreases
as the depth increases. Moreover, the rate of decrease is
greater in heavy or wet soils than in light or dry soils. When
it is understood that every living root cell derives its oxygen
for respiration from the soil air immediately surrounding
and that the oxygen does not diffuse to any extent from the
aerial parts of the plant down through the stem to the roots,
we see the probable explanation of the fact that a shallow
root system is peculiar to a heavy or wet soil. In this con-
nection, it should be stated 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 14 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 réle of absorption, then,
as well as anchorage.

160 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 161

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-

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

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

Il

162

BOTANY OF CROP PLANTS

the stamens and pistils are borne in separate inflorescences on

Fic. 58.—A
single branch of
the staminate in-
florescence of
corn (Zea mays).

the same plant (Fig. 57). The staminate
flowers are in a panicle at the top of the
stalk; this inflorescence is known as the
“tassel.” The pistillate flowers are borne
in a spike which is placed in the axil of a
leaf lower down on the stem. When mature,
the pistillate inflorescence is called the “ear.”

Staminate Inflorescence, (‘tassel’) —The
rachises of the panicle are long, slender, and
spike-like. One may distinguish between the
central and latergl spikes of the panicle. In
the central spike (Fig. 58), there are usually
from four to eleven rows of spikelets, in pairs.
Lateral branches usually have only two rows
of spikelets, in pairs. One spikelet of each
pair is pedicellate, the other sessile (Fig. 59),
or in some cases both may be sessile: The
groups of spikelets may overlap.

Staminate Spikelet—Each normal stami-
nate spikelet bears two flowers, each produc-
ing three perfect stamens and a rudimentary
pistil (Fig. 60). The glumes are seven- to
twelve-nerved, and about equal in size. The
lemma is three- to five-nerved’and the palet
two-nerved. The two lodicules are fleshy
and truncate. The anthers are long. The
upper flower of a spikelet matures! first; its
palet is larger than the lemma, while in the
lower flower, the lemma is larger than the
palet. i

Pistillate Inflorescence (‘‘ear’’) General

Characteristics —The ear (Fig. 61) is borne on a short

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

lat
spikelet

sessil
spitelet

Fic._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, Morphologically2—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

Fic. 60.— Longitudinal

section of staminate
spikelet of Country Gen-
tleman sweetcorn, X15.
G, glume; Pa, palet; An,
position of one of the
lateral anthers; L, lem-
ma; A, dorsal anther.
P, rudimentary pistil; J,
joint of rachilla. (After
Weatherwax.)

a fusion of a number of two-rowed
pistillate spikes. Since each spikelet is
two-flowered, and the lower abortive,
there are often formed the two distinctly
paired rows. The cob is said to be
formed by the fusion of separate rachises.
Opposed to the above theory is that of
Montgomery, who holds that the ear
develops ‘‘directly from the central
spike of some _tassel-like structure
similar to the well-known corn tassel.”’
His evidence for this belief may be
summarized as follows:

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

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

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

spike has the greater number of rows of spikelets.
4. He has observed the development of pistillate flowers

from staminate ones.

This development is as follows:

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.

Fic. 61.—Corn (Zea mays). Young pistillate inflorescence (‘‘ear"’), showing
the long styles (‘‘silks"’).

(c) Lemma and palet of upper flower become reduced
while the lower flower becomes abortive.

(d) Sessile flower becomes pistillate.
(e) Both flowers become pistillate.

166 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-like structure,

A femmi H
i pall

¢

{|
4 plete of sterile fl

Fic. 62.—Pistillate spikelet of corn, much enlarged. (After Nees.)

bearing hermaphrodite flowers.” He says further: “As
evolution progressed, the central tassel came to produce only
staminate flowers, these being higher and in a better position
to fertilize the flowers on the lower branches. At the same
time, the lateral branches came to produce only pistillate
flowers, their position not 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 entirely enclosed in the leaf sheaths’’ (the husks).

Pistillate Spikelet.— Each normal pistillate spikelet has two

ZEA 167

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

eens,
a ore ~,
r

re

; 4

1 n

. 1
cua bi

1 \
é
eA

et A

WY 3
p --4--4- iv
st ---\--3 Eo

SHE

Fic. 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; Si, 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

1 Stewart has noted, in the Country Gentleman variety of corn, that some
spikelets bear two well-developed flowers inside each pair of glumes. He
further points out that the irregularity in the arrangement of grains on the
ear may be due to the development of the second flower in some of the spike-
lets, which tends to throw some of the grains out of line. The same has been
noted by Sturtevant and Kempton.

168 BOTANY OF CROP PLANTS

on the edges. The lemma and palet of the fertile flower are
short, broad and membranous. In pod corn, glumes, lemma,
and palet attain a considerable size and enclose the grain.
The single ovary bears one long style, the corn “‘silk,’”” which
is forked at the tip. It is well to remember that there is one
silk for each grain on the cob. Weatherwax considers the
corn silk a compound stigma rather than a style. The silk
is indeed receptive to pollen a good portion of its length,
possibly all. A hot, dry wind may wither the silks, thus
destroying their receptivity to pollen. Fertilization of the
ovules consequently does not take place, and the ovules do
not mature. The short protuberance at the top of the ovary
is considered by Weatherwax to be the style. It is traversed
by a canal, the stylar canal. Three small rudimentary
stamens have been observed by Baillon, and Weatherwax, in
the fertile flower; the lodicules are absent. The small
aborted flower has rudimentary stamens and pistil about
equally developed; the lodicules are present.
Hermaphroditic Flowers.—Ordinarily in corn the flowers
are imperfect, that is either staminate or pistillate. Perfect
or hermaphroditic flowers sometimes occur, however. Herma-
phroditic flowers are far more common on the tassel than on
the ear. East and Hayes record a sterile dwarf mutation
which had nothing but hermaphroditic flowers. Hermaphro-
ditic flowers have the stamens reduced. Lodicules are well
developed in staminate flowers, reduced in hermaphroditic
flowers, and altogether absent in fertile pistillate flowers.
Montgomery observed hermaphroditic flowers on normal
types of ears. The plants from these seeds came true to
type. The seed was normal in every respect except that it
had three fully developed stamens coming from near the
base of the ovary. There were also three small stamens in
the aborted flower of each pistillate spikelet. The plants

ZEA 169

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

Opening of the Flowers, and er eee ee
tion, consequently cross-fertilization, is the rule in corn but
self-fertilization frequently occurs. Wind and gravity are
the chief factors in pollen dissemination, although bees
visit the flowers and are evidently concerned in pollen
dispersal; they are relatively of far less importance than
wind.

In the case of the staminate inflorescence, the first flowers
to open are those near the upper part of the central spike;
blooming spreads both upward and downward, more rapidly
downward. The same order of blooming occurs on the
branches of the tassel.

The time of pollen shedding depends upon weather con-
ditions. Cold, wet, weather retards or even prevents the
shedding of pollen. On the other hand, droughty conditions
hasten the shedding of pollen, but delay the appearance of
silks. Hence it may happen that under these conditions
much of the pollen is scattered before the stigmas are pro-
truded and receptive, and an incomplete filling of the ear
results. Onsunshiny 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-

170 BOTANY OF CROP PLANTS

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

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

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

The size of pollen grains in corn varies. Pollen produced
by central spikes is larger than that produced by laterals.
Livingston observed that in Leaming corn the pollen grains
from the central spikes were 0.02 millimeter larger on the
average than those from lateral spikes. Of 12 varieties
examined, Gernert finds that the average diameter of the
pollen grain of corn varies from 0.08 to 0.1 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 pollinate all the silks of an ear.
Unfavorable climatic conditions, such as cold, wet weather
or extremely hot days, may account for the incomplete
“filling out”’ of ears.

The silks are receptive throughout their length. Best
results are obtained when silk receives the pollen within a
few days after its emergence from the husk. Silk exposed
by splitting down the husks proved receptive. Again,
fertilization is not prevented when tips of silks are
cut off.

Fertilization, and Development of the Grain.—Just prior
to fertilization, the ovary of 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 ona 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. Single row of epidermal cells.

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

3. Single layer of inner epidermal cells.

True records the presence of a pit “‘a short distance from

172 BOTANY OF CROP PLANTS

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

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

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

1. Outer integument disappears.

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

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

4. Cells of nucellus disappear to a large extent.

5. Hardening of the cell walls of the pericarp.

6. Fusion of pericarp and inner integument.

Xenia in Corn.—Xenia is the term applied 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, fertilized with sweet corn

174 BOTANY OF CROP PLANTS

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

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

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

oe

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

The Mature Grain of Corn.—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,
Jemma, and _ glumes of the pistillate spikelets. The point of
Sy re career
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 full. 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.
EMmbEyos.2 oss Sane ee ees Ree it qauteaae II.o
Tip Caps. cask ganna swank Muyo tiled Atos Paaihlns 5
Ei | | ea a ee oe 6.0
Aleurone layer..............000...000000 ee 8.0 to 14.0
Horny endosperm.................0...00...004. 45.0

Starchy endosperm.................0.020.00 000, 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

Pic. 65.—Variation in the shape of corn grains. Which is the best propor-
tioned kernel? Why? (After Mich. Agr. Exp. Sta. Bull. 34.)

cent.). The germ is rich in oil, being composed of about 35
“to 40 per cent. of oil and 19 to 20 per cent. protein. As
much as 80 to 85 per cent. of the total oil content of the kernel
occurs in the embryo.

In high-protein 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.

Corn Starch Distinguished from the Other Common
Starches.—The following key, adapted from Winton’s
Microscopy of Vegetable Foods, gives the characteristic
microscopic differences between the common commercial
starches.

All or most of the grains rounded, not from aggregates.
Grains rounded, with central hilum; small grains globular or angular,
Wheat.
Grains large, of various shapes, with excentric hilum, Potato.
Grains polygonal or rounded, with one or more facets, mostly from aggregates.
Grains very small, sharply angular, Rice.
Grains large, polygonal or rounded; hilum with clefts, Maize.

Germination of Corn.—The germination of corn may be
judged from the following data: Sachs says: optimum 91°F.,

12

178 BOTANY OF CROP PLANTS

maximum 114.8°F., and minimum 41°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 :*

Zea tunicata, pod corn.

Zea everta, pop corn.

Zea indurata, flint corn.

Zea indentaia, dent corn.

Zea amylacea, soft corn.

Zea saccharata, sweet corn.

Zea amylea-saccharata, starchy sweet corn.

BU ee ei

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

ZEA 179

Gernert describes a type of corn with branching cars 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 witha peculiar waxy endosperm. Zea

a
a

vese,

fan
fa

‘

Fic. 66.—The six principal types of corn. From left to right, pod corn,
pop corn, flint corn, dent corn, soft corn, and sweet corn. (Afler Montgom-

ery.) CR ng

canina Watson, the Maiz de Coyote, is a branching plant
producing many small ears (2 to 4 inches long) on lateral
branches. It has been produced artificially by crossing a
common maize and teosinte. It is said to grow wild in
Mexico at the present time. Zea mays japonica is an orna-
mental sort with small, flinty grains. Zea mays hirta is a
hairy, South American corn. Zea mays curagua is a form
with serrate leaves.

180 BOTANY OF CROP PLANTS

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

Key To “Species Groups” oF Corn

Each kernel enclosed in husks (glumes, lemma, palet); the ear is also
enclosed in husks; a rare form, considered by some to be the primitive
type, Zea tunicata (pod corn).

Each kernel naked, not enclosed in pod or husk:

Grains with popping properties; popping is due to the turning inside out of
the kernel through the explosion of the contained moisture when heat
is applied; pericarp is thick and tough; éxcessive proportion of horny
(corneous) endosperm; kernels and ears small, Zea everta (pop corn).

Grains without popping properties.

No corneous endosperm, hence grains are soft; shaped like flint corn;
no indentation; the mummy corns of Peru, Mexico, and southern
United States probably belong to this group, Zea amylacea (soft
corn).

Corneous endosperm present.

Grains more or less wrinkled or shrivelled; kernels horny and trans-
lucent in appearance.

Grains horny throughout, Zea saccharata (sweet corn).

Grains with upper half horny and translucent, the lower half
starchy, Zea amylea-saccharata (starchy sweet corn).

Grains not wrinkled, smooth.

Starchy endosperm extending to top of kernel; corneous endosperm
at sides; shrinkage of starchy endosperm at top of grain causes a
drawing in of pericarp and hence the characterist c dent formed
(Fig. 64), Zea indentata (dent corn).

Starchy endosperm enclosed by the corneous endosperm; hence
there is no shrinkage of top of grain and no dent formed (Fig.
64), Zea indurata (flint corn).

Zea amylea-saccharata (starchy sweet corn) is a group of
only botanical interest. Some seed of this was found in the
San Padro Indian collection by Dr. Palmer and sent to
Sturtevant in 1886. This seed was planted at Geneva,
New York, but the crop failed and the seed was lost.

In Zea saccharata, the power to develop starch grains to
maturity has been lost. The starch that is formed remains

ZEA ISI

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

Fic. 67.—Teosinte (Euchlaena mexicana). (After Collins and Kempton in

Journal of Heredity.) ‘

as dent, flint, and pop corns that have lost the power to
mature starch normally.

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

182 BOTANY OF CROP PLANTS

in cultivation since prehistoric times, it is unknown in the
wild state. It is generally agreed, however, that it is dis-
tinctly of American origin. The nearest known wild relative
of maize is a Mexican grass, teosinte (Euchlena mexicana),
with which it is known to hybridize (Fig. 67).

Harshberger is inclined to believe “that Indian corn is the
result of a cross between teosinte and a race or variety of the
plant produced by successive cultivation of the wild plant
until its characters as a variety or a race have become fixed.”
Collins produces evidence to show that maize originated as a
hybrid between teosinte and as unknown grass belonging to
the tribe Andropogonez. He believes this grass to be much
like the earless varieties of pod corn (Zea tunicata). Mont-
gomery suggests that teosinte and corn had a common ances-
tor, which was a “large, much-branched grass, each branch
being terminated by a tassel-like structure, bearing herma-
phrodite flowers.’’ His views coincide with those of East
and Hayes (see page 164).

Environmental Relations.—Corn is a native of semi-trop-
ical America. Its range of distribution has been extended
widely through culture. A number of varieties will mature
grain as far north as southern Canada, and as a green fodder
it is raised in still colder regions, where the season is too short
to mature the grain.

Flint varieties are now grown quite abundantly through-
out northern Wisconsin; they are better adapted to cool
climates than dent corn. In general, corn is not a big crop
north of the summer isotherm of 69°F. The principal corn
belt of the United States is a strip running from eastern
Nebraska to western Ohio, the northern limit being southern
Wisconsin and Minnesota. This is a region with warm sum-
mer days and nights. The chief limiting factor to corn grow-
ing in the northern tier of States is cool nights.

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 1 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 Corn.—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 sweetcorn
canning industry is a large one. Corn starch from which
the protein and mineral matter have been removed by treat-
ment with dilute alkaline solutions gives a flour which is used
largely in the preparation of puddings, blanc manges, etc.

184 BOTANY OF CROP PLANTS

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

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

ZEA 185

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

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

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

Artificial Gums.—These are known as dextrins and Brilish
gums, and are made from starch. Starch is heated to a
temperature varying from 170 to 270°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,

186 ; 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 (Graminez) and the pea family (Leguminose)
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 corn
gives about go gallons of 94 per cent. alcohol.

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

ZEA 187

second in its corn output was Argentine with 338,235,coo
bushels. The ten leading States in the order of their pro-
duction of corn in 1915 were Illinois, lowa, Nebraska, Mis-
sourl, Indiana, Texas, Kansas, Ohio, Oklahoma, and Ken-
tucky. The total acreage in corn in the United States
that year was 108,321,000 and the total farm value of the
1915 corn crop, on the basis of the price of corn December 1,
was $1,755,859,000.

UNITED STATES 71.8 %

Fic. 68.—Percentage of the world’s supply of corn produced in the various
countries in 1914.

References

Bouutinsky, Gustav: Entwicklungsabweichungen beim Mais. Ber. Deut.
Bot. Gesell., 32: 179-188, 1914.
Bowman, M.L., and Crosstry, B. W.: Corn: Growing, Judging, Breeding,
Feeding, Marketing. Waterloo, Iowa, 1911.
Burtt, Davy J.: Botanical Characters of the Maize Plant. Transvaal
Agr. Jour., 7: 348-395, 1909.
Incomplete Dichogamy in Zea Mays. Jour. Bot. (London), 47:180-182,
1909.
Maize, Its History, Cultivation, Handling, and Uses. Longmans, Green &
Co., 1914.
Cotuins, G. N.: A New Type of Indian Corn from China. U.S. Dept. Agr.
Bur. Plant Ind. Bul. 161: 1-25, 1909.

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ZEA 189

Apogamy in the Maize Plant. U.S. Nat. Mus. Contrib. Nat. Herbarium,
12: 453-455, 1909.

The Origin of Maize. Jour. Washington Acad. Sci., 2: 520-530,1 912.

A Variety of Maize with Silks Maturing Before the Tassels. U.S. Dept.
Agr. Bur. Plant Ind. Cir. 107: 1-11, 1913.

A Drought-resisting Adaptation in Seedlings of Hopi Maize. U. S. Dept.
Agr. Jour. Agr. Research, 1: 293-302, 1914.

Correns, C.: Untersuchungen tiber die Kenien bei Zea mays. Ber. Deut.
Bot. Gesell., 17: 410-417, 1899.

Crozier, A. A.: Silk-seeking Pollen. Bot. Gaz., 13:242, 1888.

East, E. M.: Inheritance of Color in the Aleurone Cells of Maize. Amer.
Nat., 46: 363-365, 1912.

A Chronicle of the Tribe of Corn. Pop. Sci. Mo., 82: 225-236, 1913.

East, E. M., and Haves, H. K.: Inheritance in Maize. Conn. Agr. Exp.
Sta. Bull. 167: 1-142, rorr.

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., torr.

Gacer, 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.

GuicNnarD, L.: La double fécondation dans le mais. Jour. Bot. (Paris),
15: 37-50, Igor.

HARSHBERGER, J. W.. Maize: A Botanical and Economic Study. Contrib.
Bot. Lab. Univ. Pa., 1: 75-202, 1893.

Fertile Crosses of Teosinite and Maize. Gard. and Forest, 9: 522-523,
1896.

A Study of the Fertile Hybrids Produced by Crossing Teosinte and Maize.
Contrib. Bot. Lab. Pa., 2, 1901.

Hopkins, C. G., Smitu, L. H., and East, E. M.: The Structure of the Corn
Kernel and the Composition of its Different Parts. Ill. Agr. Exp. Sta.
Bull. 87: 77-112, 1903.

Hus, H., and Murpock, 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.

190 BOTANY OF CROP PLANTS

Experiments in Cross-fertilization of Corn, 2d Ann. Rept. Kans. Agr.
Exp. Sta., 288-334, 1890.
Experiments in Crossing Varieties of Corn. 2d Ann. Rept. Kans. Agr.
Exp. Sta., 2: 288-334, 1890.
Kempton, James H.: Floral Abnormalities in Maize. U. S. Dept. Agr.
Bur. Plant Ind. Bull. 278: 1-16, 1913.
Monrcomery, 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, 1911.
The Corn Crops. The Macmillan Co., New York, 1913.
Peirson, Henry: Abnormal Development in Maize. Jour. Bot. (London),
49: 347-348, Igrr.
PoInDEXTER, C. C.: The Development of the Spikelet and Grain of Corn.
Ohio Nat., 6, 1903.
SARGENT, ETHEL, and RoBERTSON, AGNES: The Anatomy of the Scutellum
in Zea Mays. Ann. Bot., 19: 115-123, 1905.
SHorsmiTH, 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.
STURTEVANT, E. L.: Notes on Maize. Torrey Bot. Bull. 21: 319-343, 1894.
Varieties of Corn. U.S. Dept. Agr. Office Expt. Stats. Bull. 57: 1-103,
1899.
WEATHERWAX, Pav: Morphology of the Flowers of Zea Mays. Bull.
Torrey Bot. Club, 43: 127-144, 1916.
Wesser, H. J.: Xenia, or the Immediate Effect of Pollen in Maize. U. S.
Dept. Agr. Div. Veg. Path. and Veg. Phys., 22: 1-44, 1900.

CHAPTER XV
ANDROPOGON SORGHUM (Sorghums’)

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
18 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 Io 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 théy may
occur in threes.

1 The term “sorghum” includes all the groups known in the United States
as milo, kowliang, shallu, durra, broom corn, and kafir.

91

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.

-steril
spies

i tile
spikelet

og
“N

Fic. 70.—Sorghum (Andropogon sorghum). 4, 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-

44 ——ovar
/ lemma of fertile flower

Fic. 71.—Spikelet of sorghum (Andropogon sorghum) dissected. Lodicule
x 10, all others x 5.

ent, itis 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. Asa 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 toopen. 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
theday. The stigmas may protrude to a slight extent first.
(Fig 72). They are followed by the anthers. When the flower
starts to open, the whole process takes place within from ten
to fifteen minutes. The spreading of the glumes, and the
emergence of anthers and styles may be so rapid in some in-
stances as to be seen with the hand lens. The stamens ex-
tend their full length, as a rule, and the anthers swing on long
filaments. In some cases, however, the anthers never fully
project from between the glumes, but shed their pollen, and
dry up, half or one-fourth caught by the glumes. When the
anthers are partly out, the stigmas are fully protruded. No
sooner are the anthers visible than they begin to dehisce by
two narrow slits at the tip only. The stigmas and pollen-

ANDROPOGON SORGHUM 195

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

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

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

196 BOTANY OF CROP PLANTS

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

The different types of sorghum cross readily.

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

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

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

Varieties.—The sorghums are divided into two main di-
visions: (1) 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; (1) kafir group, in-
cluding those with erect, long cylindrical heads full of
obovate seeds (kafirs, white milo, etc.); (2) durra group,
including those with thick, compact, ovate, pendant inflo-
rescences, and large, flattened seeds (yellow milo, durra,
feterita); and (3) broom corn group, in which the heads are
loose and spreading. Frequently the heads are on recurved
stems, called “goose necks.”

ANDROPOGON SORGHUM 197

Key TO THE PRINCIPAL Groups oF SorcHUM!
Pith juicy.
Juice abundant and very sweet.

Internodes elongated; sheaths scarcely overlapping; leaves 12 to 15 (ex-
cept in Amber varieties); spikelets elliptic-oval to obovate, 2.5 to 3.5
millimeters wide; seeds reddish brown, Sorgo.

Juice scanty, slightly sweet to subacid.

Internodes short; sheaths strongly overlapping; leaves 12 to 15; peduncles
erect; panicles cylindrical; spikelets obovate, 3 to 4 millimeters wide:
lemmas awnless, Kafir.

Internodes medium; sheaths scarcely overlapping; leaves 8 to 11; ped-
uncles mostly inclined, often recurved; panicles ovate; spikelets broad-
ly obovate, 4.5 to 6 millimeters wide; lemmas awned, Milo.

Pith dry.
Panicle lax, 2.5 to 7 decimeters long; peduncles erect; spikelets elliptic-
oval or obovate, 2.5 to 3.5 millimeters wide; lemmas awned.

Panicle 4 to 7 decimeters long; rachis less than one-fifth as long as

the panicle.
Panicle umbelliform, the branches greatly elongated, the tips droop-
ing; seeds reddish, included, Broom 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, Shallu.
Panicle oval or obovate, the branches spreading; glumes at maturity
appressed, not involute; seeds white, brown, or reddish, Kowliang.
Panicle compact, 1 to 2.5 decimeters long; peduncles erect or recurved;
rachis more than two-thirds as long as the panicle.

Spikelets elliptic-oval or obovate, 2.5 to 3.5 millimeters wide; lemmas
awned, Kowliang.

Spikelets broadly obovate, 4.5 to 6 millimeters wide.

Glumes gray or greenish, not wrinkled; densely pubescent; lemmas
awned or awnless; seeds strongly flattened, Durra.

Glumes deep brown or black, transversely wrinkled; thinly pubescent;
lemmas awned; seeds slightly flattened, Milo.

Origin of Sorghums.—The wild form from which our culti-
vated sorghums have been derived is Andropogon halepensis
(Johnson grass). This species is native to tropical and sub-
tropical parts of the Old World. The view is now quite

1 Taken from Ball.

BOTANY OF CROP PLANTS

198

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UMOIG ‘IT ‘eiinp UMOIQ ‘OL ‘elMp oY ‘6 ‘oprur ‘g tnypeys ‘L tayey [Myyxselq ‘9 ‘ayey yuid ‘Ss ‘yey pel‘
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Sy
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ANDROPOGON SORGHUM 199

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

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

The sorghums are either able to resist or to escape drought.
For this reason they have become one of the principal crops
on the non-irrigated lands of the West. Their resistance to
drought is due largely to their low water requirement, along
with their ability to roll the leaves with approaching dry
periods, and thus reduce the water-losing surface, and also
to their ability to remain alive during a period of drought and
quickly resume growth when moisture is available. In this
last respect the sorghums 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, CarLeTbn R.: Saccharine Sorghums for Forage. U.S. Dept. Agr.
Farmers’ Bull. 246: 7-18, 1906.
Three Much Misrepresented Sorghums. U.S. Dept. Agr. Bur. Plant Ind.
Cir. 50: 1-14, 1910.
The History and Distribution of Sorghum. U. S. Dept. Agr. Bur. Plant
Ind. Bull. 175: 1-63, 1910.
Better Grain-sorghum Crops. U. S. Dept. Agr. Farmers’ Bull. 448:
I-36, IgII.
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.
Prreer, C. V.: The Prototype of the Cultivated Sorghums. Jour. Am. Soc.
Agron., 7: 109-117, I915.

ANDROPOGON SORGHUM 201

Hartvey, CuHartes P.: Broom Corn. U. S. Dept. Agr. Farmers’ Bull.

174: I-30, 1903.
Rotuces, B. E.: Dwarf Broom Corns. U. S. Dept. Agr. Farmers’ Bull.
768: 1-16, 1916.
U. S. Dept. Agr.

WarBuRTON, C. W.. The Non-saccharine Sorghums.
Farmers’ Bull. 288: 1-28, 1907.

CHAPTER XVI
ORYZA SATIVA (Rice)

Habit, Roots, Stems, Leaves——Common cultivated
rice is an annual plant, which grows best under swampy
or very moist conditions. There are upland varieties pro-
duced with irrigation, but the lowland type is the sort
almost entirely grown in the United States. The seedling
has one seed root. The root system is fibrous; the first,
second, and third nodes give rise to adventitious roots.
The first whorl of permanent roots is close to 14 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 34 to 1 inch wide. The ligule is long, acute
or obtuse, and easily splits into two parts. Itis 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

202

ORYZA SATIVA 203

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

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

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

204 BOTANY OF CROP PLANTS

nated. The flowers at the tip of the inflorescence are the first
to open. Flower opening continues throughout the day.
The stamens are the first flower parts to
appear. After they are extended full
length, the lemma and palet open wider,
and the stigmas protrude. Usually the
stigmas draw back between the palet
and lemma after pollination, although
they may remain outside. Although
self-fertilization is the normal process,
cross-fertilization is not altogether pre-
cluded. ‘
Grain.—The rice grain (caryopsis) is
surrounded by the lemma and palet, or
palet alone. These two structures form
the “hull.” Rice enclosed in the hull is
known as ‘‘paddy.” Rice from which
Fic. 75.—Spikelet of rice the hull has been removed is ‘“‘cleaned
Pe eee rice.” The rice grain (Fig. 76) is
smooth, longer than broad, and elliptical in cross-section.
There are two longitudinal parallel ridges on
each of the flat surfaces. The grain of common
rice is shiny and transparent. This appearance
is due to the glassy endosperm. Occasionally
there are grains that appear dull; in such, the
endosperm is starchy on the outside and horny
within. Grains with dull areas here and there
are not uncommon. An interesting rice is _ Fic. 76.—
. : ’ . Kernel of rice
Oryza glutinosa, the grains of which always (Oryzasativa).
appear dull. A cut surface of this rice is de- e oe
scribed as paraffin-like in appearance. The
starch grains behave quite differently from those of common
rice. They color yellow-brown with iodine instead of violet-

ORYZA SATIVA 205

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 1o per cent. of the weight of the grain,
and a considerable quantity of ash, fat, crude fiber, protein,
and pentosans. The color of red rice is located in the seed
coat, or throughout the endosperm.

Milling of Rice.—The threshed rice from the field is called
“paddy rice.”’ The grains are enclosed by the glumes,
lemma, and palet, which together constitute the “hull.”
The hulls are removed by passing the grains between revolv-
ing millstones, set apart about two-thirds the length of a rice
kernel. The hulls are then removed by a fanning device, and
this process followed by the separation of the rough (un-
hulled) from the clean rice in the ‘‘paddy machine.’”’ The
next process removes a part of the bran layer (pericarp, testa
and nucellus) and most of the embryo. After a separation
of the powdery bran from the cleaned rice, the grains are then
led into the ‘‘pearling cone’”’ where they are scoured. This
is followed by a thorough polishing 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.

206 BOTANY OF CROP PLANTS

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

Varieties.—Carleton gives the following provisional ar-
rangement of wild and cultivated rices:

1. Oryza granulata (wild rice).

2. Oryza officinalis (wild rice).

3. Oryza sativa (cultivated rice).

(a) utilissima.
1. communis (large-kerneled rice).
2. minuta (small-kerneled rice).
(b) glutinosa (glutinous rice).

American varieties are comparatively few in number.
Three main types are grown: Honduras, Carolina and Japan.
The hulls of Honduras and Japan rice are yellowish-brown,
those of Carolina rice mostly a golden yellow. Lowland
types of rice form, almost exclusively, the sorts grown in
this country. Japan rice has smaller grains, a thinner hull,
and tillers more than the other types in the United States.
Honduras and Carolina belong to the communis group, and
Japan to the minutia group.

Distribution and Closely Related Species—There is”
is a great number of Oryza species found growing wild in
tropical regions of both hemispheres. The native home
of O. sativa is the warm parts of Asia and Africa. Culti-
vated rice probably originated in eastern Asia.

In this country, there are two quite common native
plants termed “‘rice.”” These are, Canada rice (Zizania

ORYZA SATIVA 207

aquatica), and wild rice (Zizania miliacea). Both are tall
aquatic grasses belonging to the same tribe (Oryzez) as
cultivated rice. Both species of Zizania differ from Oryza
in having moncecious spikelets.

Uses of Rice.—Rice is a food for more human beings than
is any other grain. It is the principal food of the densely
populated regions of China, India, and the neighboring
islands. The consumption of rice per capita in the United

SSS a= a

th)

Fic. 77.—Harvesting rice in Arkansas. (From Essentials of Geography,

Second Book. Copyright 1916, by Alpert Perry Brigham and Charles T.
McFarlane. American Book Company, Publishers.)
States is steadily increasing. Orientals do not polish their
rice, while all the rice that comes on the market in this coun-
try has had the hull removed, and has been polished. Rice
hulls and rice flour or polish, removed in the milling process,
are used as stock food. Rice straw is also used as a food for
stock, and in the manufacture of paper, straw hats, straw
board, etc. In Japan, a drink called “sake,” similar to
beer, is made from rice.

BOTANY OF CROP PLANTS

208

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-

yoog upru4auy

Csaaysygng ‘kunguon
‘IUDUAD TIFT °.L SapAvyD pun moysiug Krsag aqyy &Q ‘O61 ‘1y43t4k GoD

‘yoog puorvag ‘Kyg¢oasoayn fo sypyuassq wmosg) ‘suoIBar Zutonposd-sory¥— gl “oI

wioojidvg yo ojdosy, My TELA GE De ean a oe ee a ae
ee ee e VOININY
i HIAOS

ae a.

EAS caf Kad ce:
oo ‘sans We ¢ te Soe
y v
c x

i
VAL ee]

It reaches its best development in

ture is lower than 77°F.

moist regions.

Certain sorts of upland rice are planted,

But, most of the rice

cultivated and harvested like oats.

ORYZA SATIVA 2009

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

The Production of Rice.—British India produced 62,-
638,912,000 pounds of rice in 1914. During the same period,
Japan raised 17,826,240,000 pounds, Java and Madura
(1913) 7,951,049,000 pounds, Korea 3,678,878,000 pounds,
the Philippine Islands 1,403,516,000 pounds, Italy 741,263,-
ooo pounds, and the United States 656,917,000 pounds.

There are four commercial rice-growing districts in the
United States: (1) 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 1915, 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.
Nogy6é-Sekai, 1910-11.

Grauay, 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: 1-10, 1913.

Kixxawa, S.: On the Classification of Cultivated Rice. Imp. Univ. Tokyo,
Coll. Agr. Bull. III, No. 2, 11-108, ror2.

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
Chetochloa (Setaria), Panicum and Echinochloa, which are
still spoken of as the ‘‘true millets.”

Agriculturally speaking, the word “millet” embraces
a number of annual cereal and forage grasses which have
comparatively small seeds, abundant foliage, and a fibrous
root system. They are raised in Europe and the United
States for forage purposes and in a number of Asiatic and
African countries for human food as well.

Most of these millets belong to the four genera Chetochloa,
Echinochloa, Panicum, and Pennisetum, of the tribe Panicee.
. Ragi or finger millet (Eleusine coracana) belongs to the tribe
Chloridee. It is grown in India to quite an extent as a
cereal but has never attained favor in the United States.

Key to Principat 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).

1 After Frear. 210

MILLET 211

Inflorescence spicate; involucre of bristles below cach spikelet.
Grain enclosed in lemma and palet (the hull) at maturity; spike loose,
Chetochloa (foxtail millet and foxtail grass).
Panicle usually 1 centimeter thick or less; bristles commonly green;
spikelets about 2 millimeters long, C. viridis (green foxtail).
Panicle usually 1 to 3 centimeters thick; bristles usually purple; spike-
lets, 2.5 to 3 millimeters long, C. italica (foxtail millets).
Grain globose, forcing open the hull as it matures, and falling free when
threshed; spike dense, Pennisetum glaucum (pearl millet).

PENNISETUM GLAUCUM (Pearl Millet)

Stem.—The plants are erect, and from 3 to 8 feet tall.
The culms are cylindrical and pithy; the upper internodes are
smooth, the 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 34 to 1 inch thick. The main axis is
stiff and thick-hairy. The side branches are hairy, 7 to 8
millimeters long, and bear each one to three (commonly two)
spikelets, which are surrounded by a cluster of bristles.
These bristles fall with the spikelets at maturity.

Spikelet and Flower—The lower glume is short, broader
than long, and truncate; the inner glume is longer, about
one-half the length of the spikelet, oval, and three- to four-
nerved. Each spikelet has two flowers, the lower stami-
nate, the upper perfect. The lemma of the lower staminate
flower is oval, and three- to four-nerved; the palet is small,
sometimes entirely lacking, the stamens three in number, and
lodicules absent. The staminate flower in the spikelet often
has both palet and stamens lacking, and in some instances
the spikelet has but one flower, the staminate one being en-
tirely lacking. In some few instances, spikelets contain two
perfect flowers. The lemma of the fertile flower is oval,

212 BOTANY OF CROP PLANTS

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

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

Fic. 79.—Millets. 1, Common; 2, Hungarian; 3, Siberian; 4, Golden Won-
der; 5, Japanese Barnyard; 6, German; 7, Pearl.

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

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

MILLET 213

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

Varieties.—There is considerable variation in length and
thickness of the inflorescence, color of inflorescence, and color
of grain. No varietal classification
has been made. Pearl millet is
sometimes sold under the name of
“Pencilaria”’’ (Penicillaria) or
Mand’s Wonder Forage Plant.
There are many common names for
Pearl millet, some of which are cat-
tail millet, African millet, Indian
millet, Egyptian millet, horse millet,
and Japan millet.

Origin.—The wild form from which
pearl millet has come is unknown.
It is probable that tropical Africa is
its native home.

PANICUM MILIACEUM (Proso, Hog or
Broom-corn Millet)

Stem.—The plants are erect, some- ee ee ee eee
times decumbent at the base, and millet (Panicum milia-
often reach a height of 3 to 314 feet. °C™: *?
Branches frequently arise from the basal nodes, and they
may bear inflorescences. The culms are cylindrical, and
rough-hairy or smooth below the nodes.

Leaf (Fig. 80)—The leaf sheaths are open. They are
covered with very small protuberances (papillae) from each
of which arises a stiff hair; at the sheath nodes the hairs are
shorter and not mounted upon papille. 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. 81),
4 to ro inches long; the erect or ascending branches are some-

i

Fic. 81.—Inflorescence of proso millet (Panicum miliaceum).

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

MILLET 215

Spikelet and Flower.—The spikelets are oval in shape and
444 to5 mm. long. The lowermost glume is broad, pointed,
five- to seven-nérved, 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 Jemma 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 effusum.—Panicle broad, the
branches spreading to all sides.

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

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

Origin.—The native home of Panicum miliaceum is not

216

known.
Asia from the earliest times.

BOTANY OF CROP PLANTS

The plant has been cultivated in Europe and

CHATOCHLOA ITALICA (Foxtail Millets)

Fic. 82.—Spikelet of foxtail millet
(Cheztochloa italica). X15.

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 14 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.

MILLET 217

Spikelets and Flower.—The spikelets are elliptical, and
usually shorter than the bristles, which subtend them.
Each spikelet (Fig. 83) has two flowers, the lower ster-
ile, the upper with both stamens and pistil. The lower-
most glume is oval, pointed, three-nerved, and about one-
third the length of the spikelet. The second glume is
five-nerved, and slightly shorter than the spikelet; it sur-
rounds the lemma of the sterile flower. The lemma of
the fertile flower is broad-oval, and five-nerved; the palet
is about the same length as its lemma. Both lemma and

!

y . im nd
| YU
gore Sterile flower fertile “flower 2nd glume

Fic. 83.—Dissected spikelet of common millet (Chatochloa italica). X10

palet of the fertile flower are smooth, shining, hardened
structures. The lodicules are fleshy. There are three
stamens. The ovary is long-oval and smooth; its style has
two long branches, with the rudiment of a third.

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

Mature Grain (Fig. 84) —The lemma and palet enclose
the mature kernel. The grain is oval, shining, 2 to 214 milli-
meters long and 114 to 1}4 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

218 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 Chetochloa italica:

Fic. 84.—A, grain of foxtail millet (Chetochloa 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). X1I0.

1. Chetochloa italica maximum.—Heads_ long, open,
and drooping. This group has two subdivisions: (1)
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. Chetochloa italica moharium.—Heads short, thick,
erect, or drooping but veryslightly. This group also has two
subdivisions: short-bristle and long-bristle varieties. Here
belongs Hungarian millet.

Key To PrRincipaL Types oF FoxtarL MILLETS (CHATOCHLOA ITALICA)!

Heads small, uniform, compact, seeds yellowish to black with usually a
large percentage very dark; beards brown or purple, Hungarian Millet.
Heads large, more or less open; seeds more or less bunched.
Heads long, slender, very open, lax, drooping; seed groups very distinct,
Aino Millet.
Heads shorter and plumper, bushy, erect or slightly drooping; seed groups
indistinct.
Seeds yellow.
Profusely bearded; medium large heads.
Heads large, seeds small, seed groups more distinct, German Millet.
Heads small, seeds large, seed groups less distinct, Common Millet.
Sparingly bearded; heads very large, Golden Wonder Millet.
Seeds red or pink, Siberian Millet.

Origin of Foxtail Millet—-The stem form of the foxtail
millets is Chetochloa viridis, the green foxtail. It differs
from the cultivated forms in that its fruit falls from the
inflorescence when mature. Chetochloa 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 14 to
2 feet long, 14 to 1 inch wide, and have smooth, glabrous
sheaths and smooth or scabrous blades.

Inflorescence, Spikelet, Flowers, and Fruit—The inflores-
cence is a panicle made up of from five to fifteen sessile, erect
or ascending branches; the lower branches may be spreading

1 After Frear.

220 BOTANY OF CROP PLANTS

or reflexed. The spikelets are ovate, green or purple, and
densely crowded in two to four rows on one side of the rachis.
Each spikelet has two flowers: a lower staminate, and an
upper perfect. Within the two empty glumes is the lemma
of the staminate flower; then follow the lemma and palet of
the perfect flower, both of which are hard and parchment-like
in texture. The lemma of the staminate flower is awned,
that of the perfect flower abruptly pointed. There are three
stamens, and two plumose stigmas. The kernel is firmly
surrounded by the hardened lemma and palet.

Distribution.—Barnyard grass is a native of Europe. It
is now widely distributed as a weed in cultivated soil and in
waste places.

ECHINOCHLOA FRUMENTACEA (Japanese Barnyard Millet)

In general characters, Japanese barnyard millet corre-
sponds very closely to common barnyard millet, except that in
the main, it has a more nearly erect habit, more turgid seeds,
is awnless, or has very short awns, and is brown or purplish in
color. It is known as Sanwa millet in India, and “billion-
dollar grass”’ in the United States. It probably originated
from common barnyard millet (E. crusgalli).

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. 168: 1-16, 1903.

CHAPTER XVIII
PHLEUM PRATENSE (Timothy)

Description.—Common timothy is a perennial grass, from
114 to 5 feet high. Corms or bulbs form in the lower leaf
axils, a single seedling sometimes having from eight to twenty.
These bulbs develop in the fall of the year, live through the
winter, and send up new shoots the following season. Thus
we see that the plant reproduces vegetatively as well as by
seeds. In cultivation the plant shows marked variation in
stem, leaf, and inflorescence characters, in earliness, duration
of bloom, longevity, vigor, stooling power, disease resistance
and yield of hay and seed. The leaves are flat, and three to
eight per stem; the upper sheaths are long, usually exceeding
the internodes, and slightly inflated; the ligule is rounded.
The inflorescence is cylindrical and spicate; although it is
often called a spike, it is in reality a contracted panicle. The
spikelets are one-flowered. Each spikelet is subtended by
two membranous, compressed glumes which are ciliate on the
margins (Fig. 85), truncate at the tip and awned; the lemma
is much shorter and broader than the glumes, thin, truncate,
and finely toothed at the apex; the palet is narrow and thin.
Stamens are three in number. There are two distinct styles
with plumose stigmas. The whole process of blooming and
dehiscence of anthers takes place in about one and one-half
hours. Clark observed that the average number of days the
individual heads remain in bloom varies from seven to ten.
The upper third of the head blooms first. The time of bloom-
ing is just before daybreak. The egg-shaped grain is enclosed

222

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.

Fic. 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. Itis an important crop at high altitudes in the Rocky
Mountains, where it is usually mixed with Alsike clover.

It will grow on both clay and loam soils, and does best
when lime is present.

Closely Related Species.— Mountain timothy (Phleum alpinum) is common

in meadows from Labrador to Alaska, in the mountains of both the East and
the West, also Europe, Asia, and temperate South America. The inflores-

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

CxLaRK, CHARLES F.: Variation and Correlation in Timothy. Cornell Agr.
Exp. Sta. Bull. 279: 1-350, 1910.
Observations on the Blooming of Timothy. Plant World, 14: 131-136,
Igil.
WEBBER, H. J.: The Production of New and Improved Varieties of Timothy.
U.S. Dept. Agr. Bur. Plant Ind. Bull. 313: 339-381, 1912.

CHAPTER XIX
SACCHARUM OFFICINARUM (Sugar Cane)

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

Stems.—The stem is of the usual grass type—divided
into a number of joints. The cylindrical, solid culm is
8 to 15 feet high, and 1 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
thaninthe upper. Around the culm, at the bud, are several
rows of dots; roots arise from these dots when the cane is
planted, or when in any way it is brought into contact
with the soil. Sugar cane “suckers” readily. The plant is
propagated entirely from stems. The whole stalk may be
used or only the lower parts of the stools, the so-called
“rattoons.”

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

Inflorescence, Flowers, Fruit.—The inflorescence is a loose
panicle, 1 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 spikelet is two-flowered; the lower one is
sterile and consists of a palet; the upper is fertile and has
a lemma and palet, two minute lodicules, one to three sta-
mens, and a single ovary with two stigmas. There is a tuft
of long, silky hairs at the base of each spikelet. The grain

Fic. 86.—Mill where sugar caneiscrushed. (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 vitality. Mature grains are seldom
produced in cultivated plants and pollen is often infertile.

Geographical.— Saccharum officinarum is a native of the
tropics. It is now grown as a crop throughout our Southern
States and in many other warm regions. It is not a success

SACCHARUM OFFICINARUM 227

north of the latitude of 33°. The roots are unable to stand
a temperature much lower than 15°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 ro 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 utilized as a fuel to run the mill.

The juice that flows from the rollers is turbid, due to
the impurities which it contains. It is strained, and then
milk of lime isadded. The limed juice is heated with steam.
The impurities unite with the lime, and appear as scum on
top or as a sediment at the bottom of the purified juice.
The clear juice is run into vacuum evaporators, where it is
concentrated to the desired point. The concentrated juice
is then pumped into tanks, where crystallization is brought
about.

The grain of the sugar is 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 fertilizer. It is rich in phosphorus and
potash.

Production of Cane Sugar.—The world’s production of
cane sugar during the 1913-1914 campaign was 11,225,000
short tons (excluding Central America). During the same
period, the world production of beet sugar was 9,430,145
short tons. Sugar-cane production in the United States is
confined almost exclusively to southern Louisiana, and to
Texas, immediately adjoining.

LEADING COUNTRIES IN THE PRODUCTION OF CANE SUGAR, 1913-1914

Country Short tons
Cub awiiss 32 cee es Aad Cees Sink EN To ee Ss 2,909,000
British, Pnidta ices e i iis/ 29 anectcdewyia ¥ songs, Pose sAd Gs tod bees 2,566,000
VV Aisi ance Ait On 2a ONS otek eA. ce htaat es 1,541,000
AWA. sioner hes plR WR ee Anes oad ee 612,000
Philippine Islands...............00.....0000 00s 408,000
Australiazand Fijisscees gceaece ceeds eats cen 4a 407,000
Porto: Rico? sas ou yorc soe sew hae g ok as 364,000
AT RONEN A osictcads Bdsans died Maal enn ound wile ah aA 304,000
t Umited ‘States 4.2 22 aapneacnn Awe asennaeee aeons 301,000

Matritluss ewecieanan erate braid eerie omues Hog yess 275,000

CHAPTER XX
LILIACE (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 tulip are chief among those cultivated as
ornamentals.

Habit, Roots.—Most members of the family are fleshy
herbs from bulbs or rhizomes. Some species of Aloe and
Dracena, however, are shrubs or small trees. In herbace-
ous forms, the roots are mostly fibrous and shallow, sometimes
fleshy and extending to considerable depths in the soil.

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

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

229

230 BOTANY OF CROP PLANTS

Inflorescence and Flowers.—There are a number of
different types of inflorescences in the family. The flowers
are often single or solitary, as in the lilies; or racemose, as in
the soapweed and hyacinths; or umbellate, asin 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.
31 and 87). The stamens are attached

segments to the receptacle or to the perianth.

The anthers are usually large and con-

en Spee bacon spicuous. The superior ovary is

(Allium cepa). three-celled, has one style and a
three-lobed stigma.

Fruit and Seeds.—The fruit is a capsule or berry. The
capsule is a dry, splitting (dehiscent) fruit with several united
carpels. When the carpels split down the middle line as
they do in lilies, the dehiscence is said to be loculicidal.
It is distinguished from septicidal dehiscence of capsules,
in which the carpels open along the line of their union, as in
rhododendron, and from poricidal dehiscence in which the
carpels open by pores, as in the poppy. The berry is a fleshy
fruit possessing several to many seeds which are more or
less imbedded in the fleshy ovary wall (pericarp).

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

Saad

LILIACEE 231

ALLIUM

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

Fic. 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.

Stems.—With but few exceptions, species of the genus
Allium bear bulbs. In chives (Allium schenoprasum), the
bulbs are very small (Fig. 88), and in Welsh onion (Allium
fistulosum) and leek (Allium porrum), they are nearly always

Fic. 89.—Leek (Allium porrum).

absent (Figs. 88 and 89). In the common onion (Allium cepa),
they are large and well developed. Examination of the
mature bulb of the common onion shows it to be made up of
the much thickened bases of leaves, attached to a compara-
tively small, conical stem (Fig. 14). This is best seen in a
median, longitudinal section. From a terminal bud on this
small, underground stem, there is sent up a long hollow or
solid, leafless stem (Fig. 90) (scape) bearing an inflorescence
at the top, which in this case is an umbel. Lateral buds are

LILIACEZ 233

sometimes borne in the axils of the leaves, and these may also
develop into flower shoots.

Leaf.—The first foliage leaf emerges from a slit in the
cotyledon. All leaves are very thick and fleshy, and over-
lapping. There is no petiole. The oldest leaves are on the

Fic. 90.—A, base of stem of common onion (Allium cepa) showing hollow
leaves cut across; B, cross-section of hollow stem of same: C, base of stem of
leek (Allium porrum) showing flattened solid leaves; D, cross-section of solid
stem of same.

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

234 BOTANY OF CROP PLANTS

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

Fic. 91.—Umbel of onion (Allium cepa).

spathe, consisting of two (rarely three) papery bracts. The
spathe encloses the entire umbel in the bud. The pedicels
are long and slender. |

Flower.—The flowers (Fig. 87) are regular and periect..,
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

LILIACEE 235

filaments are usually dilated at the base, and the anthers are
oblong, and opening inward (dehiscing inward). The single,
superior ovary is imperfectly three-loculed and bears a

Fic. 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;
f, first true leaf; k, hypocotyl; s, slit from which the first true leaf emerges. A
considerably magnified. (After Bergen and Caldwell.)

single filiform style, which may be more or less indistinctly
three-cleft at the apex.

Pollination.—Species of Allium are insect pollinated. The
anthers of the flower usually mature before the stigma, al-

236 BOTANY OF CROP PLANTS

though the reverse is sometimes the case. The inner circle
of stamens is the first to shed pollen.

Fruit——This is a three-celled, membranaceous capsule
with loculicidal dehiscence. Two seeds, black in color,
are usually borne in each locule of the capsule. The seeds
(Fig. 92) are convex on one side and almost flat on the other,
and possess a large quantity of oil. The embryo is cylin-
drical and curved. ,

Germination of Seed, and the Seedling.—At the beginning
of germination, the primary root is forced out by the growth
of the curved end of the embryo (Fig. 92). The curved
end of the embryo, the cotyledon, comes out of the ground
in the form of a closed loop. The tip of the cotyledon re-
mains attacked to the endosperm and seed coat. When the
soil is loose, the endosperm and seed coat may be pulled
from the ground, but in case it is compact, they remain
beneath the ground. The cotyledon absorbs nourishment
from the endosperm. When this is used up, the cotyledon
tip withers and becomes detached from the seed coat. At
the base of the cotyledon, where it joins the hypocotyl, there
early appears a longitudinal slit; 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 (T’ig. go).
Leaves keeled, very narrow, Allium sativum (garlic).
Leaves keeled, very broad, Allium porrum (leek).

LILIACE 237

Leaves cylindrical and hollow (Fig. 90).
Plants forming a dense clump with very small bulbs, Allium schano-
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 (Garlic)

Garlic is a perennial herb. The bulbs are composed of
several small, elongated, egg-shaped bulbils, called “cloves,”
all of which are enclosed by a
whitish skin (Fig. 93). There
are often as many as ten bulbils
in a single bulb. The scape is-
from 1 to 2 feet high, round,
and possesses alternate, broad-
linear, solid, 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
Fic. 93.—Bulb of garlic (Allium cloves are used more commonly

sativum). xX 4.
than seeds.

Garlic 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 OF CROP PLANTS

ALLIUM PORRUM (Leek)

Leek is a very robust biennial plant. The bulbs are
small. The tall scape is solid and bears broad, solid, keeled
leaves (Fig. go).

Leek is a native of the Mediterranean region.

The edible portions of the plant are the bases of stems and
leaves. Thestemsare 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 Cives)

Chives (Fig. 88) are hardy perennials bearing small,
white, narrowly ovoid, clustered bulbs with membranous
coats. The scape is stout and up to 2 feet high. The leaves
are linear, terete, and hollow, 7 or 8 inches in length and borne
in dense tufts. The rose-colored flowers are in dense, globu-
lar umbels. Although the plant flowers profusely, it seldom
produces seeds. It is propagated by division of the tufts of
bulbs.

Chives are natives of Europe, Asia and North America.
In this country, they grow wild from New Brunswick to
Alaska, south to Maine, northern New York, Michigan,
Wyoming and Washington.

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

ALLIUM ASCALONICUM (Shallot)

This is a perennial herb with small, oblong-pointed bulbs
about 1 inch in diameter and 2 inches long (Fig. 94). The

LILIACEE 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.

Fic. 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, cylindrical and hollow (Fig. go).

Fic. 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.

LILIACEE 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. mulliplicans).
Potato onions.
Multipliers.
z. Propagated by inflorescence bulblets or “tops” (Fig. 95) (Allium cepa
var. bulbellifera). ?
Top onions.
Tree onions.
Egyptian onions. -

Fic. 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).
(b) Bulbs indifferent in color, reddish or yellowish (Yellow Danvers,
Prizetaker, Strasburg).

The “multiplier”? onions have compound bulbs (Fig. 97),
copper-yellow in color, with rather thick skin and mild flavor.
When large bulbs are planted, they segregate into a number
of bulbs, and each produces six to twelve stalks. The potato

Fic. 97.—Cross-section of a multiplier onion bulb. (After Bailey.)

onion is a hardy ‘‘multiplier,” sometimes called English

multiplier. The principal use of the “multiplier” group is
in the production of ‘‘bunchers” for the early market. There
are both white and yellow “multipliers.” ;

In “top,” “tree,” and “Egyptian” onions, clusters of bulb-
lets are produced at the top of the scape. Some primordia
develop into flowers and others into bulblets. In some cases,
ail 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
Italian onions. As compared with American types, they are
larger, less hardy, the flesh is more tender and mild, but they
do not keep as well. On account of their tenderness, the
foreign types of onions do best in Florida, Texas, and south-
ern California. Seed of the Bermuda onion is produced
successfully only in Teneriffe, one of the Canary Islands,
off the west coast of Africa. Attempts to grow seed in the
United States have given comparatively poor results. The
Prizetaker is our best example of a Spanish onion. Impor-
tant varieties of Italian onions are the Barletta, White
Italian Tripoli, White Rocco, and Giant Gibraltar. There
are numerous varieties of American onions, well-known ones
being as follows: Red Wethersfield, Southport Globe
(white, yellow and red), Danvers, American Prizetaker,
White Portugal, Silverskin 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 OF CROP PLANTS

organic compound of sulphur, allyl sulphide. The com-
pound is volatile to a high degree, and is broken down by
heat; consequently the onion is milder when cooked than
when raw. Asa rule, white varieties are milder than yellow
and red kinds, although there are exceptions to this.

Uses of Onions.—Onions are most commonly used as a
vegetable, but in many instances for flavoring purposes.
The small varieties such as Queen, Barletta, and American
Silverskin are used for pickling. The Egyptian (perennial
tree onion) and multipliers are valued for the production
of bunchers. It is considered that the allyl sulphide in
onions stimulates the flow of digestive juices and hence
they are often recommended for those having a tendency to
constipation. Again, on account of the small amount of
starch and sugar they contain, onions are made a part of
the diet of invalids who are not allowed starchy foods.

ASPARAGUS

Generic Description——Members of the genus Asparagus
are all perennial plants with rather fleshy roots and short
rootstocks. From the latter, arise branching aerial stems,
which are sometimes annual, as in the common edible
asparagus (A. officinalis), or perennial as in A. laricinus,
one of the ornamental asparagi. The stems are erect or
climbing, in some instances (A. falcatus) reaching a distance
of 25 feet or more. The small leaf-like structures along the
stem, the so-called ‘“‘leaves,”’ are in 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 4 245

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

--perianth
; =rudimentary gesent
Stamens Pperianth
ell scale
developed leaf
prstil
3 % 1
cladophills /
Scale Ee LY

Ny | *D

Fic. 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 branching, position of flowers and leaves.

six in number and inserted at the bases of the perianth
segments; the filaments are distinct and filiform, and the
anthers are ovate or oblong, with introrse dehiscence. The
superior ovary is sessile, three-lobed, with a short, slender
style and three short, recurved stigmas. The fruit (Fig. 98)

246 BOTANY OF CROP PLANTS

is a globose berry with two seeds (sometimes more), in each
of the three locules. The seeds are subglobose, often dark in
color. The embryo is cylindrical.

Economic Importance of Genus.—The genus Asparagus
contains about 150 species distributed throughout tem-
perate and tropical parts of the Old World. There are
numerous ornamental species, the most common being
Asparagus medeoloides (smilax), A. plumosus (the plumy
asparagus), a climbing plant used for decorative purposes
and often called ‘asparagus fern,” and A. sprengeri, another
‘‘asparagus fern,”’ much used for planting in hanging baskets.
The only edible species of any consequence is Asparagus
officinalis, the common garden asparagus.

ASPARAGUS OFFICINALIS (Asparagus)

The common garden asparagus is a much-branched peren-
nial herb reaching a height of 3 to 7 feet.

Roots.—The roots (Fig. 99) are numerous and fleshy, ex-
tending horizontally in the soil to some distance, but being
confined to the surface layers. They arise both from the
sides and bottom of the thickened rootstock. Each year new
roots are produced and the older ones die and become hollow,
without becoming separated from the stem. New roots ap-
pear above the older, which accounts for the so-called
“lifting” of the plants.

Stems.—Asparagus bears both subterranean and aerial
stems. The underground stems are rootstocks. They are
much thickened, branched, rather woody, and about as long
as broad. The rootstock or “crown” makes an annual growth
of 1 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

LILIACEZ 247

edible portion of the plant. The scales borne on these fleshy
shoots are true leaves. At lenthg, the stems become much
branched. The filiform cladophylls (Fig. 98) are mostly
clustered in the axils of the minute scales. They perform
the function of leaves, as is evidenced by their green color.

From the time of seeding, it is usually four years before the
rootstock is vigorous enough to allow cuttings to be made.

Fic. 99.—Garden asparagus (Asparagus officinalis). A, young shoot cr
‘‘spear"’; B, thick, fibrous roots and young shoots arising from “crown.”

However, good crops have been produced two years after
seeding. The plant may be propagated by divison of the
rootstocks, but the common method is by seeding.

Leaf.—The true leaves (Fig. 98) are minute scales sub-
tending the whorls of cladophylls. They do not perform leaf
functions.

Flower.—The flowers are small, drooping, greenish-yellow
and usually solitary, but sometimes in twos or more at the

248 BOTANY OF CROP PLANTS

nodes. Each flower is borne on a short, slender jointed
pedicel (Fig. 1co). The perianth is campanulate (bell-
shaped), about 6 millimeters long, the segments being linear

Fic. 100.—Garden asparagus (Asparagus officinalis). Portion of pistillate
plant in fruit, on left; and of staminate plant in flower, on right.

and obtuse. The stamens are shorter than the perianth

lobes. The single ovary has a short style, a three-lobed

stigma and three locules. Common asparagus is dicecious—

LILIACEE 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:

Propuct From Firty PLants Eacu, STAMINATE AND PISTILLATE

| Fifty staminate Fifty pistillate

' plants, ounces plants, ounces
First period, tendays............... 3a: 21
Second period, tendays............. 104 68
Third period, ten days...............3 266 164
Fourth period, ten days............. 203 | 154
Total for season................. 610 | 407

|

This shows a gain of the staminate plants over the pistillate
plants of about 50 per cent. for the whole season, the greatest
difference being in the first period. Hence, it seems to show
that staminate plants are earlier and more productive than
pistillate ones. Fruit production makes a greater demand
for food than does the formation of stamens. It is for this
reason that staminate plants are able to produce a greater
growth of ‘“‘spears”’ than pistillate ones.

Pollination—Common asparagus is insect-pollinated.
The nectaries are small and concealed at the base of the
perianth. Staminate flowers are first to open.

250 BOTANY OF CROP PLANTS

Fruit.—This is a red, spherical berry (Fig. 98) with three
cells, each of which usually contains two seeds. The perianth
is persistent in the fruit. The dark, somewhat triangular
seeds run about fifty to a gram. They preserve their germi-
nating power for four or 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 1o 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:

LILIACEZ 251

The Palmetto is grown most in the south, and is well-known
on account of its resistance to asparagus rust (Puccinia
as paragi).

Uses.—The common asparagus is used as a vegetable.
As a rule the tender shoots are eaten fresh, but large quan-
tities are also canned each year. The principal canning
factories are located in California and on Long Island, New
York. For canning, Conover’s Colossal and Palmetto have
given the best satisfaction. A method has been devised by
which the seft 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

BarLey, L. H.. Preliminary Synopsis of Onions and Some of Their Allies.
Rep. of Prof. of Hort. and Landsc. Gard., 26th Ann. Rept. State Bd.
Agr. Mich., 94-98, 1887.

Gorr, 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., 115-132, 1901.

CHAPTER XXI

MORACEE (Mulberry Family)

The mulberry family has about 925 species in 55 genera,
occurring in ~trspical and temperate regions of both hemi-
spheres. It possesses 2 number of plants of ‘considerable
economic importance. Several Asiatic species of the genus
Ficus yield a sap from which rubber is made. Ficus carica
is our cultivated fig. The India rubber plant of green-
houses and in homes is Ficus elastica. Artocarpus communis
is the well-known bread-fruit of the tropics. Toxylon
pomiferum is the osage orange, a tree whose wood is valuable
for wheels, posts and other small articles; it is also planted
for ornament. The paper 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 Jeaves are petioled (stalked), stipule-bearing, and borne
oppositely or alternately on the stem. The flowers are in
ament-like spikes or heads on stalks which arise in the axils
of leaves. An ament is a spike-like inflorescence each flower
of which is subtended by a conspicuous bract. The flowers
may be moneecious or dicecious. In the staminate flower,
the calyx is three- to six-lobed or parted, the petals are
absent, and the stamens are one to four, inserted at the base
of the calyx. The filaments are thread-like, and erect or
inflexed in the bud. In the pistillate flower, the calyx consists

252 :

MORACE 253

of three to five partly united sepals. The single superior
ovary is one- to two-celled and bears one to two styles.
The fruit is drupe-like in mulberries, an achene in hops and
hemp, and a synconium in figs. ;

Key To PRINCIPAL GENERA

Trees or shrubs.
Flowers not in a receptacle; buds scaly, Morus (mulberry).
Flowers inside of a hollow receptacle; buds naked, Ficus (fig).
Herbs. 5
Erect herbs, Cannabis (hemp).
Twining herbs, Humulus (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 /eaves are conduplicate (Fig. 101) in the bud,
alternate, serrate, three-nerved, often deeply lobed, and
deciduous. The stipules fall soon after development. The

convolute plicate conduplicate

Fic. 101.—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 (moncecious) or on different trees (dicecious).

254 BOTANY OF CROP PLANTS

The staminate inflorescences are long, cylindrical catkins.
They soon fall. The calyx of the staminate flowers is deeply
divided into four rounded lobes. The three or four stamens
are inserted at the base of the calyx, beneath the rudimentary
pistil. The filaments are thread-like, inflexed in the bud
and uncoil like a spring at the moment of anther dehiscence.
The two-celled anthers open lengthwise and shed their
pollen toward the inside of the flower (introrse dehiscence).

The pistillate inflorescences are short, dense catkins. The
flowers in these have a deeply four-lobed calyx, the two outer
lobes being the broader. All the calyx lobes are persistent,
become fleshy, and enclose the ovary in the fruit. The
sessile ovary possesses one cell, and a single style divided
almost to the base into two very slender, hairy stigmas.

Fruit.—Each ovary develops into a nutlet bearing rem-
nants of the styles at the tip and enclosed by the thickened,
juicy calyx lobes. There is a single seed within each fruit.
However, the mulberry “fruit”? as commonly understood;
is not a single drupe-like structure, as given above, but an
aggregate of these, z.e., an entire pistillate flower cluster.
The single fruits are very much crowded together, making up
a collection, which commonly goes by the name “mulberry.”

Other “Mulberries.”—The so-called paper mulberry
(Papyrus papyrifera),anative of eastern Asia and now planted
for ornament in many parts of eastern and southern United
States, may be easily distinguished from the true mulberries
(Morus) by its non-edible globular fruit and the occurrence
of its pistillate flowers in heads. In some sections of the
country, the “flowering raspberry” (Rubus odoratus) is
confused with and often called a ‘‘mulberry.” It is true that
the fruit of this has some resemblance to a mulberry “‘fruit,”
but instead of bearing its single drupe-like fruits along an
axis, the true drupes of the raspberry are borne on a receptacle.

MORACEE 255

The “fruit” of the mulberry is a collection of one-seeded
fruits developed from a number of separate flowers in a dense
inflorescence, while the raspberry ‘fruit’? represents the
matured ovaries of a number of pistils belonging to a single
flower.

Geographical.—The genus Morus is a native of eastern North America,
higher altitudes in Mexico, Central America, Western South America, Asia,
Japan, and the Indian Archipelago.

Key To Principat Species oF GENUS Morus

Leaves smooth beneath, sometimes slightly hairy on the veins.
Fruit white or pinkish; leaves becoming light green above, Morus alba
(white mulberry).
Fruit black; leaves becoming dark green and shining above, Morus nigra
(black mulberry).
Leaves hairy beneath; fruit red or purplish, Morus rubra (red mulberry).

MORUS ALBA (White Mulberry)

Description.—This is a low-branched tree, sometimes
reaching a diameter of 2 feet. The slender, round twigs are
at first hairy, later becoming light grayish brown. The leaves
are light green, with prominent whitish veins, and variously
lobed or divided. The staminate inflorescences are 1 to 2
centimeters long, slender and drooping. The pistillate ones
are from 14 to rcentimeterlong. The fruit is white or pinkish
in color, 1 to 2 centimeters long, and poor in quality.

Geographical.—The white mulberry is a native of Asia, probably of China.

It has spread throughout Europe and has also become naturalized in eastern
United States.

Types and Varieties.—Economic Importance.—There are
_a number of types and varieties of the white mulberry.
According to L. H. Bailey, the following are forms or off-
shoots of Morus alba: Morus alba var. tartarica (Russian mul-
berry) and Morus alba var. venosa. The Russian mulberry

256 BOTANY OF CROP PLANTS

is a very hardy, low, bushy tree with small fruit which va ies
in color from white to red and almost black. It is an im-
portant wind-break and shelter-belt tree in the Great Plains.
Teas’ weeping mulberry is an ornamental variety of the
Russian. Morus alba var. venosa (M. nervosa) is an orna-
mental curiosity bearing jagged leaves with white, prominent
veins.

Morus multicaulis (M. alba var. multicaulis) was intro-
duced into America in 1826 and, for a while, gave a great
impetus to the attempts to grow silkworms. It is a small
tree with rough, long-pointed leaves.

The chief horticultural varieties of the white mulberry are:
New American, Trowbridge, Thorburn and Downing. The
Downing is supposed to be a variety of M. multicaulis.
However, the so-called Downing of most nurserymen is the
New American.

Early Attempts in the United States to Grow Silk.—The
white mulberry has been cultivated from the earliest times,
chiefly for feeding the silkworm. In 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 roth century, silk culture was again agitated.
There existed what has been called ‘‘ The Morus multicaulis
mania.” This species was introduced into America in 1826,
and since it was thought to be the source of the renowned
Chinese silk, soon gained wide fame here. The ‘‘craze”’
died down in about 1836, and since that time, there has been
little effort to grow silk in North America upon a commercial
scale.

Uses.—As has been said, the white mulberry is the one
upon which silkworms are raised. In the Old World the

MORACE 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 1 to 2 feet. The numerous
branches are slender, slightly hairy at first, but later become
smooth and brownish gray. The Jeaves 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
staminate inflorescences are 1 to 2 centimeters long. _ The pis-
tillate inflorescences are from 5 to 8 millimeters long. The
fruit is black, 1 to 2 centimeters long and hasa 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 Jeaves 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. Thepistillateinflorescences are muchshorter than
the staminate ones. The fruzt is bright red, becoming nearly
black, sweet and juicy, and about 1 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.

MORACEE 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). Theangle 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-

Fic. 102.—Dextrorse twining
of hop stem,

260 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 dicecious, rarely
moncecious. 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.

Staminate inflorescences (Fig. 103, B) are paniculate, and
grow from the axils of the main shoot or from the axils of
lateral ones. Pistillate inflorescences (Fig. 103, A) are spike-
like in appearance. They are the “hops” of commerce and
are often spoken of as “‘burrs’”’ or “‘strobiles.’”” These are
mostly borne on lateral branches from the main stem; they
arise in the axils of the leaves.

The pistillate inflorescence has a central, hairy axis (Fig.
103, C) upon which are arranged a number of very short
lateral branches or axes. At the base of each short lateral
branch, or axis, is a pair of bract-like structures. These are in

MORACEE 261

Fic. 103.—Hop (Humuluslupulus). 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: (1) two bract-like stipules; (2) brac-

y-—ovary
jt —perianth

Fic. 104.—Hop (Humulus lupulus). <A, single staminate flower; B, two
pistillate flowers with bracteoles and bract-like stipule. (B after Wossidlo.)

teole and first flower; (3) bracteole and second flower; (4)
bracteole and third flower; (5) bracteole and fourth flower.

Flowers.—The staminate flowers (Fig. 104, A) measure
about 6 millimeters in diameter. They have a five-parted
calyx, no corolla, and five stamens opposite the calyx lobes.
Each pistillate flower (Fig. 104, B) is subtended by a single
bracteole (Fig. 105, A) that partially encloses it at maturity.
It has a single ovary surrounded by a cup-shaped perianth.
There is one style with two long stigmas, which are covered
their full length with papille.

MORACE 263

Pollination, Fertilization, and Development of the
“Hops.”—The long, brush-like stigmas adapt the plant
to wind pollination. When the pistillate inflorescences
are young, the stigmas protrude from ‘between the small
‘““bracts’” and become very conspicuous. Only the basal
bracts of the inflorescence are to be seen. As soon as
fertilization has taken place the stigmas (“brush”) drop
off and the “bracts” rapidly increase in size.

The necessity for fertilization to secure the best develop-
ment of the “hop” has been determined by a number of
observers. The hops will only develop properly when
a certain number of bracteoles bear seeds. If the young
pistillate inflorescences (‘‘burrs”) are enclosed in paper bags
to prevent fertilization, no seeds result, and the hops are
poorly developed. It is true that the bracteoles develop
to some extent without fertilization of the ovules, but the
bracteoles connected with normal seeds are much larger and
a brighter yellow than those bearing rudimentary seeds.
Furthermore, hops, not fertilized, remain in blossom longer
than those fertilized. Howard has shown that hops arti-
fieially 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 g2 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

bility that the soil is more quickly exhausted by seeded
hops than by seedless ones.

The Mature Fruit.—The fruit (Fig. 105) is a small achene
surrounded by the persistent cup-shaped perianth. The
single seed within has a curved
embryo about which is a small
amount of endosperm.

Lupulin Glands.—In the ma-
ture hop, the outer surface of
the bracteoles, the perianth,
and, to a less extent, the bases
of the bract-like stipules are
covered with yellow pollen-like
grains, the so-called ‘‘hop-meal”’
or ‘lupulin’’ (Fig. 105).

Each yellow grain is a cup-
shaped, multicellular, glandular
hair filled with a resinous secre-
tion. It is an outgrowth of an
( epidermal! cell and consists of a

e527 D short stalk and a cup of one

Fic. 105.—Hop (Humulus lupu- layer of cells. Each cell has a
owls gad: © aie ee at rather thick cuticle. The secre-
oo ge derek parr 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

MORACE 205

northern part of the continent of Europe and in Asia as far as
eastern Siberia and south to Persia; it also grows wild in
North America, across the continent westward to New
Mexico and British America. It requires a moist, cool cli-
mate to attain its best development. Oregon, California,
New York, and Washington are the leading States in the
commercial production of hops.

Closely Related Species—— Humulus japonicus, the Japa-
nese hop, is grown as an ornamental plant. It is an annual;
its pistillate inflorescence does not enlarge into a ‘“‘hop.”
Along streams from Wyoming to Utah, New Mexico and
Arizona, there is a hop (Humulus lupulus neomexicanus)
which is distinguished from the Linnean species by its more
deeply divided leaves and more sharply acuminate bracts.

Varieties.—There are a number of varieties of hops, based
upon length and color of vines, size, shape and color of hop,
shape of bracteoles and stipular bracts, aroma, lupulin con-
tent and time of ripening. In California the chief variety is
Large Gray American. Common New York varieties are
English Cluster, Pompey, Humphrey Seedling and Canada.

Composition.—The composition of the strobiles or hops is
of great importance, for they possess the valuable constitu-
ents of the plant, most of which reside in the lupulin glands.
There are four principal active ingredients in the “‘lupulin,”
as follows:

1. Essential oil.

2. Non-resinous bitter principle.
3. Resins.

4. Tannin.

Hop oil is volatile and gives the hop its characteristic
aroma. The amount of essential oil in hops varies from o.2
to 0.8 percent. The non-resinous bitter principle of the hop

266 BOTANY OF CROP PLANTS

hop is probably the alkaloid, lupuline. Of the resins in the
lupulin glands, two principal ones have been identified, a hard
and a soft resin. ‘The hard resin has a slight bitter taste and
little or no antiseptic power in the beer wort. The soft
resins are much more bitter, imparting this taste to the beer
wort; they also prevent the growth of bacteria in the wort
and thus have a preservative effect. The total resin content
of hops varies from 10 to 18 per cent. Hop tannin makes
up about 4 to 5 per cent. of the hop. It is thought by some
that it serves to precipitate the albuminous material from
beer wort.

Uses of Hops.—In some European localities, young hop
sprouts are used as an early spring vegetable. The ‘most
tender sprouts are those which have been covered with soil
during the winter. :

Before the days of yeast cakes, yeast for bread-making was
made by cultivating wild yeast in a decoction of hops and
water. Some of the material obtained was mixed with the
dough. The various constituents extracted from the hops
add flavor to the bread, and also have antiseptic properties.

The most important use of hops, however, is in the brewing
process. Preparatory to their use in the breweries, the hops
are taken through a curing process in which they are kiln-
dried, and then subjected to the fumes of burning sulphur.
“‘Sulphuring”’ bleaches the hops, and acts as a preservative.
After the sweet beer wort is made in the brewing process, it
is boiled with hops. In this process, among other effects,
the flavor of the wort is improved by the extraction of the
active ingredients in the hops. The essential oil of the lupu-
lin glands imparts an aroma to the beer, the non-resinous
‘bitter principle and the resins give to the hopped wort a slightly
bitter taste, and the tannin probably serves to precipitate
albuminous substances. Moreover, the malic and citric

MORACEZ 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 climbers (lianas). A number of species are
parasitic on other trees. A parasite is an organism which
secures its food material from another living organism. A
complete parasite has no power of making its own food as do
those plants which possess chlorophyll. The Golden Fig
(Ficus aurea) begins life as an epiphyte; the seed germinates
in the crevices of other trees; the aerial roots that are first
produced take root when they strike the soil, and hence be-
come trunk-like. Aerial roots may be sent down from
branches, take root and also form trunks. The banyan tree
(Ficus benghalensis) also starts its life on the bough of a tree,
receiving all its nutriment from substances available on the
bark. Hence in its early life the banyan is an epiphyte.
When once rooted in the soil, the plant becomes independent.
In the East Indies, the banyan is ‘‘universally known as an
immense living columned hall, consisting of a flat expanded
canopy of leaves and numerous stem-like prop roots growing
down from the boughs”’ (Schimper’s Plant Geography).

Leaves.—The J/eaves 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.

Fic. 106.—Pollination of the fig (Ficus carica). A, medium lengthwise
section of a synconium containing fertile pistillate flowers; note the female fig
wasp near the orifice, also another one which is inside. 8B, similar section of
synconium showing gall flowers. (Afler 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.
brevifolia, are native to peninsular Florida and the Keys,
while F. carica has been introduced into southern California

MORACEE 269

and a number of the Gulf States. As compared with other
genera in the family Moracez, 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 slightly heart-shaped. ‘There are five to seven deep lobes,
which are coarsely toothed or slightly lobed again; each lobe
is blunt at the tip. The leaves are light green, rough and
hairy on the upper side, paler and hairy on the under side;
leaf venation is prominent.

Inflorescence, and Flowers.—The numerous small flowers
line the inner wall of a hollow receptacle (Fig. 106), except
near the small opening (‘‘eye’’) at the apex where there are
scales or small leaves.

Among the various types of Ficus carica, there are four
distinct kinds of flowers, staminate, pistillate, gall and mule.

Staminate Flowers (Fig. 107, E)—These rarely occur in
cultivated figs, being found for the most part in the wild
fig (Caprifig). They occur just below the scales in the
receptacle. Each staminate flower usually has a four-lobed

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272 BOTANY OF CROP PLANTS

insect has been a topic of great interest to students of botany.
Pollination in the Caprifig will be considered first.

Crops of Fruit in Caprifigs.—Jn 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. Asa result, a few fully developed seeds are
found in the second crop of Caprifigs. In August or Sep-
tember the eggs, deposited in the gall flowers of the second
crop, hatch out. The mature female wasps emerge from the
receptacle, in search of other figs in which to lay their
eggs. By this time the third crop of Caprifigs is about one-
fourth grown.

Third Crop (Mamme).—The figs of this crop possess
staminate and gall, but no female flowers. When they
are about one-fourth grown, in August or September,

MORACE 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’ fertilization.
Such is not the case with some other types, particularly
Smyrna figs. The latter have only pistillate flowers and,
unless these are fertilized, the receptacle does not 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 fertilization as applied to figs
is termed caprification. In this horticultural process, a
number of first-crop figs (profichi) of the Caprifig are sus-
pended on the branches of the Smyrna tree. The female
Blastophagas which hatch from the eggs in the gall flowers
of the profichi become covered with pollen as they emerge
from the figs. In search of a place to lay their eggs, they
go to the partly mature figs of Smyrna. They enter the
orifice of the fig and scatter pollen on the stigmas, and fer-
tilization of the ovules ensues. The pistillate flowers of the
Smyrna fig, unlike the gall flowers, have styles of such a
length that the wasps are unable to lay their eggs in the
proper place. Consequently, the wasps perish in the
fruit and their bodies are absorbed by the growing cells.
Gall flowers are the only ones in which eggs may be laid prop-
erly, and hatch.

In California, caprification of Smyrna figs is done in
June or July. The second crop of San Pedro figs and
the first crop, but not the second, of Adriatic figs, require
caprification.

Effects of Fertilization (caprification). In caprifigs, as has
been noted, there are two general types of receptacles: those

18

274 BOTANY OF CROP PLANTS

possessing pistillate flowers (mammoni) and those without
pistillate flowers (profichi and mamme). The effects of
fertilization may be observed in comparing the behavior
of caprificated figs of the mammoni with the non-caprificated
ones of the profichi and mamme, or the non-caprificated ones
of the mammoni.

Prior to fertilization, the figs of the two types are about
the same size. Caprificated figs become larger than those not
fertilized; they cling to the tree more tightly, the ribs are
more pronounced and the branches that bear them grow
more vigorously.

As has been indicated, Smyrna figs must be caprificated
to bring about the development of the ovaries and seeds and
the proper ripening of the receptacle. The superiority of
Smyrna figs is due to the aromatic flavor of the seeds.

The Mature Fruit.—The “‘fruit” of fig (Fig. 106) is termed
a synconium. This is a pear-shaped receptacle on a very
short stalk; the nutlets (true fruits), when present, are im-
bedded on the inside of the fleshy receptacle walls. At the
apex of the fig, is the “eye” or orifice of the receptacle.
The ‘“‘neck”’ and “cheeks”’ (sides) of the fruit are marked by
a number of rings. The fruits vary widely as to size, form,
neck, stalk, ribs, eye, color of skin, color of pulp, seeds,
quality and growth.

Geographical.—Ficus carica is considered to be a native
of southern Arabia. Some one or more of its different types
are now grown in most of the tropical and subtropical coun-
tries. The first figs brought into the United States were a
common edible type and were introduced into California by
the Franciscan order of Mission Fathers. From California,
they have spread and are now being cultivated in many of
the Southern States. Fig culture in the cooler sections of the
United States is very limited, and special care needs to be

MORACEZ 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 (proficht),
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 J/eaves are alter-
nate above and opposite below. They are compound,

MORACEE 277

digitate, with five to eleven linear-lanceolate, pointed and
serrate leaflets. Hemp is dicecious. The staminate in-

florescences (Fig. 108, A)
are in axillary, narrow and
loose panicles, the pistillate
in erect, leafy spikes, also
axillary. The staminate
flower is borne on a slender
pedicel subtended by a
bracteole; it has five dis-
tinct sepals and five short
stamens. Each pistillate
flower (Fig. 108, B) is sub-
tended by a leafy bract,
and possesses a single,
thin, entire calyx segment,
wrapped about the ovary.
The ovary has two thread-
like feathery stigmas.
Hemp is wind-pollinated.
The ovary matures into
an ovoid, hard achene.
The curved embryo is
imbedded in a fleshy endo-
sperm. The fruits of
hemp are much larger
and heavier when grown
in a moist habitat than
when grown in a dry
one.

Fic. 108.—Hemp (Cannabis sativa).
A, branch of staminate plant; B, single
pistillate flower. (B after Wossidlo.)

Geographical.—The native home of common hemp is central and western
Asia. It has spread, as a result of cultivation, throughout Europe, Asia and
America. In many places, it has escaped from cultivation and become a

rather troublesome weed.

278 BOTANY OF CROP PLANTS

Varieties.—Nearly all hemp grown in this country is of
Chinese origin. The Japanese hemp is identical, or very
similar, to Chinese hemp. European varieties (Piedmont,
Neapolitan, Hungarian, and Russian), often termed Smyrna
types, differ from the Chinese and Japanese ones in that the
plants are shorter, the growth is more compact, the seeds are
in denser clusters and earlier in maturing. The best quality
of hemp fiber comes from Italy.

Fic. 109.—Cutting hemp, Kentucky. (From Essentials of Geography,
Second Book. Copyright, 1916, by Albert Perry Brigham and Charles T.
McFarlane. American Book Company, Publishers.)

The Hemp Industry in the United States.—Since about the
year 1906, there has been a slight decline in the domestic
production of hemp. This falling off has been due to the
difficulty of obtaining laborers to do the work of retting,
breaking, and preparing the fiber for the market; to the lack
of development of labor-saving machinery; to the fact that
greater profits are derived from raising other crops in hemp-

MORACEE 279

growing regions; and to the greater use of other fibers in the
manufacture of products formerly made of hemp.

Kentucky began to raise hemp in 1775, and that State now
leads in hemp production. Kentucky now furnishes the
seed for nearly all of the hemp grown for fiber in the United
States; the hemp from this State is mostly of Chinese
origin. The chief hemp-growing States are Kentucky, Cali-
fornia, Nebraska, Indiana, New York, and Wisconsin.

Preparation of Hemp for Market.—Harvesting Hemp —
In some places, hemp is still harvested by hand with a reaping
knife or hemp hook. However, in most hemp-growing dis-
tricts, sweep-rake reapers, mowing machines, or self-rake
reapers are used.

The hemp stalks, usually 8 to 14 feet long, are bound into
bundles about 1o 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

280 BOTANY OF CROP PLANTS

portion (“hurd’’) of the stem. Water-retting is practised in
European and Asiatic countries. The stalks are immersed in
streams, ponds, or artificial tanks.

Breaking.—In the breaking process, the inner cylinder of
wood is broken in pieces, which permits it to be removed,
leaving behind the long bast or hemp fibers. The removal of
the broken pieces of woody tissue is known as scutching. In
this country, both hand breaks and machine breaks are in
use. The stems must be dry before breaking, so as not to
injure the fibers.

Hackling.—The long, straight hemp, known as rough
hemp, is sorted and hackled by hand. Im 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

MORACEX 281

25 per cent. of an oil, which is sometimes extracted and used
as a substitute for linseed oil. The drug Cannabis indica
is derived from the stems and leaves of common hemp, which
under the hot climatic conditions of India, chiefly, develop a
volatile oil and a strong narcotic resin (cannabin). These
substances are secreted by the glandular hairs on stems and
leaves. They are not produced toany extent in cold climates.
Hemp-seed oil is used for making soft soaps, as a paint oil,
and low grades are utilized for certain varnishes. Recent
tests show that a fair quality of paper can be made from
hemp “‘hurds.”

The chief fiber competing with hemp is jute. Jute is
produced in India from two species of plants, Corchorus
capsularis and Corchorus olitorius. It is used extensively
for the manufacture of sugar sacks, gunny sacks, burlaps,
grain sacks, and wool sacking. It is about two-thirds as
strong as hemp fiber of the same weight, and is not as durable.
Although hemp has been used to some extent in the manu-
facture of binder twine, most of the binder twine now is made .
from the fibers of sisal and abaca.

Sisal Hemp.—The main center of production for Agave
fibers is Yucatan in Mexico. On the low limestone plains of
this country, Agava sisalana thrives. It belongs to a differ-
ent family (Amaryllidacee) 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.

282 BOTANY OF CROP PLANTS

- References

Baitry, L. H.: Mulberries. Cornell Agr. Exp. Sta. Bull. 41: 223-243, 1892.
Sketch of the Evolution of Our Native Fruits. The Macmillan Co., 1898.

Briant, Lawrence, and Meacuam, C.S.: Hops. The Influence of Climate,
Ripeness, Soil, Drying, and General Manipulation on the Value of Hops.
Jour. Fed. Ins. Brewing, 2: 423, 1896.

CuHapman, A. C.: The Essential Oil of Hops. Proc. Chem. Soc. (London),
9:177, 1893; 10: 227-229, 1894. Jour. Chem. Soc. (London) Trans.,
67: 54-63, 1895a. Jour. Fed. Inst. Brewing, 4: 224-233, 1898. Jour.
Chem. Soc. (London) Trans., 83: 505-513, 1903.

The Hop and its Constituents. A Monograph on the Hop Plant. London,
1905. Published by Brewing Trade Review.

CueEpsEY, M.: The Influence of Pollination upon the Development of the Hop
(Humulus lupulus). Plant World, 8: 281-283, 1905.

Cook, O. F.: Sexual Inequality in Hemp. Jour. Hered., 5: 203-206, 1914.

EIsen, ‘Gustav: Edible Figs, their Culture and Curing. U.S. Dept. Agr.
Div. Pom. Bull. 5: 1-33, 1897.

The Fig: Its History, Culture, and Curing. U.S. Dept. Agr. Div. Pom.
Bull. 9: 1-317, 1901.

Biological Studies on Figs, Caprifigs, and Caprification. Proc. Cal. Acad.
Sci., ser. 2, vol. 5: 897-1003, 1896.

Gross, E.. Hops in Their Botanical, Agricultural, and Technical Aspects
and as an Article of Commerce. Scott, Greenwood & Co., London, 1900.
Transl. from German by C. Salter.

Howarp, A.: Hop Experiments in 1904. Councils Kent and Surrey. South-
eastern Agr. Col., Wye, Bull. 1: 1-29, 1904-5.

The Influence of Pollination on the Development of the Hop. Jour. Agr.
Sci., 1: 49-58, 1905.

Howarp, L. O.: The Present Status of the Caprifig Experiments in California.
U.S. Dept. Agr. Div. Ent. Bull. 20 (new ser.): 28-35, 1899.

Smyrna Fig Culture in the United States. U. S. Dept. Agr. Yearb., 1900:
76-106, Igor.

Mattuews, J. M.: The Textile Fibers: Their Physical, Microscopical, and
Chemical Properties. John Wiley & Sons, 1911.

Myrick, H.: The Hop: Its Culture and Curing, Marketing, Manufacture.
Orange Judd Co., 1899.

Power, F. B., Tutin, F., and Rocerson, 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: L15-159, 1914.

MORACEZ 283

SaLmon, E.S.,and Amos, A.: Onthe Valueofthe MaleHop. Jour. Southeast.
Agr. Col., Wye, 17: 365-391, 1908. ;

SaLmon, E. S.: The Pollination and Fertilization of Hops and the Characteris-
tics of “Seeded” and ‘“‘Seedless” Hops. Jour. Agr., 21: 22-31, 123-133,
1914.

The Pollination and Fertilization of Hops and the Characteristics of
“Seeded” and ‘‘Seedless” Hops. Jour. Bd. Agr. (London), 2: 123-
133; 3: 23-220; 20: 953-966; 21: 22-31, 1914.

ScumipT, J.: Investigations on Hops, V. On the Aroma of Hops. Compt.
Rend. Lab. Carlsberg, 11: 149-163, 1915.

STOCKBERGER, W. W.: Change of Sex in Humulus Lupulus not Due to Trau-
matism. Abs. in Sci., n.s. 31: 632, 1910.

Tovurnois, J.: Sexual Studies of the Hop Plant. Ann. Aci. Nat. Bot., 9 ser.,
19: 49-191, 1914.

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

CHAPTER XXII

POLYGONACE (Buckwheat Family)

Herbaceous representatives of this family are largely found

Fic. 110.—Leaf of common buckwheat
(Fagopyrum vulgare). X11.

in temperate regions, tree-
like species in American
tropics, while shrubby ones
are limited to western Asia.
There are about 30 genera
and 800 species. Rhubarb
and buckwheat are the prin-
cipal cultivated members,
while a number of species of
Rumex (dock), and of Polygo-
num (knotweed, bind-weed,
etc.) are bad weeds.
Stems.—The stems are
conspicuously jointed and
usually swollen at the joints.
The leaves are alternate
(Fagopyrum), opposite (Ma-
counastrum), or whorled
(mountain sorrel, Oxyria
digyna). They are mostly
entire, rarely lobed or divided.
The stipules, with a few ex-
ceptions, are membranous,
sheathing, and united to

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

(Fig. 110).

284

POLYGONACEE 285

Inflorescences.—The inflorescences vary a great deal
within the family; in buckwheat they are panicled racemes,
in Polygonum spp., terminal or axillary spike-like racemes,
in Eriogonum spp., cymes, umbels or heads. The cyme is a
determinate type of inflorescence. In this type, the terminal
flower is the oldest and subsequent ones open in order from
the inside to the outside of the inflorescence (centrifugal open-
ing of the inflorescence). In the head type of inflorescence,
so well exemplified by the dandelion or sunflower, the flowers
are crowded on the receptacle; the stalk of each flower is
very short or entirely absent; it is an indeterminate type.

Flowers.—The flowers are small, mostly perfect, rarely
dicecious or monececious, and radially symmetrical. In
the genus Friogonum, 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 filiform, mostly distinct
but sometimes united in a ring at the base, and commonly
dilated at the base; the anthers possess two cells, and are
longitudinally dehiscent. The pistil is solitary. The su-
perior ovary is one-celled, three-angled or.compressed, rarely
four-angled, and usually sessile; the styles are most frequently
three in number, rarely two or four, and attached to the apex
of the ovary; the stigmas are capitate (head-shaped) or
tufted, and sometimes two-cleft. Within each ovary there
is a single ovule.

Fruit——The fruit is a three-angled (rarely four-angled)
achene, about which is frequently the persistent calyx; the

286 BOTANY OF CROP PLANTS

pericarp is hard or leathery. The single seed in each fruit
assumes the shape of the pericarp; the seed coat (testa) is
membranaceous, the endosperm is abundant and mealy, and
the embryo is straight or curved.

Key To PrincipaAL GENERA

Flowers subtended by involucres; ocree wanting, Eriogonum.
Flowers not subtended by involucres; ocrez 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

Fic. 111.—Rhubarb (Rheum) flower, external view, median lengthwise
section, and with perianth and stamens removed. (After Liirssen.)

well-developed root system. The rhizome is used in the
propagation of the plant. In the spring, a number of large
leaves are sent up from the underground stem, and, later in

POLYGONACEE 287

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

Fic. 112.—Rhubarb (Rheum rhaponticum) plant in fruit.

as they require considerable food supply which should go
to the support of the roots. The leaves are large, circular
in outline, cordate at the base, and with sinuate veins
beneath; leaf petioles are semi-cylindrical and bear membran-

288 BOTANY OF CROP PLANTS

ous ocree. 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. 111) 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.

persisten i!
calyx lobe

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

Self-pollination is prevented to a large degree by the matu-
ration of anthers before the stigmas. Stigmas of flowers
below on the inflorescence receive pollen from the anthers of
younger flowers borne above them. Pollen is disseminated
by wind, insects, and gravity.

Fruit——Rhubarb fruit (Fig. 113) is an achene surrounded
at the base with the persistent remains of the perianth; it has
three broad, thin wings which are traversed by a longitudinal
nerve running near the margin; it is tipped by a small per-

POLYGONACEE 289

sistent style. The seeds are three-angled, conforming in
shape to the fruit; the testa is thin and red; the hilum and
micropyle are basal; the endosperm is abundant and sur-
rounds the large, straight embryo. Good-sized plants can
be raised from seed in one season if it is planted early. The
seedlings of rhubarb show interesting variation.

Geographical, and Varieties——The common rhubarb is a
native of Asia. Jt has become introduced into many coun-
tries of the temperate climates. It is a cool season crop that
will withstand summer heat, and the roots winter freezing.
It is claimed that a number of the varieties now grown
are hybrids between R. rhaponticum, R. undulatum and
R. palmatum. The principal varieties grown are Linnzus,
Victoria and Monarch. There are a number or ornamental
species of Rheum, most of which are distinguished from com-
mon rhubarb by their more or less lobed leaves, the margins
of which may be coarsely or finely toothed.

Uses.—Rhubarb or pie plant is a vegetable used for its
large, acid leaf stalks, which are of the best quality early in
the season. The leaf stalks are usually made into pies or
sauce, and occasionally wine ‘is made from the juice.

FAGOPYRUM VULGARE (Common Buckwheat)

Roots.—Common buckwheat is an annual, from 2 to 4 feet
tall. It hasasmall root system. There is a single primary
root which may reach down to a distance of 3 or 4 feet; side
roots are given off along the primary, but they do not extend
far into the soil. Buckwheat differs from the true cereals, in
the possession of a single primary root, and a much less
extensive root system.

Stems.—The stems are quite succulent, smooth, except at
the nodes, and strongly grooved. Each seed gives rise to but
one stem which may branch freely, but, unlike grasses, no

19

290 BOTANY OF CROP PLANTS

“suckers” or ‘tillers’? are produced. The amount of
branching depends upon the thickness of seeding; the plants
branch freely when not crowded and feebly when crowded.
The young stems vary from green to red, and turn brown
with age.

Fic. 114.—Buckwheat (Fagopyrum vulgare).

Leaves.—The leaves are alternately arranged on the stem
and characteristically hastate (halberd-shaped) (Fig. r10), or
triangular heart-shaped; they may be sessile or short-
petioled, and bear an ocrea (Fig. 110), which soon falls off. ©

POLYGONACEE 291

Inflorescence.—The inflorescence is a raceme which may
be either paniculate or corymbose (a corymb is a flat-topped
raceme type of inflorescence); it is terminal and axillary,
many-flowered, and erect or slightly drooping.

=———receptacle
a P

,

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

Flowers.—The flowers (Fig. 115, D) are white, tinged with
pink. There are no petals (hence is apetalous), but there is
a five-parted corolla-like calyx which remains attached to the

292 BOTANY OF CROP PLANTS

base of the fruit. There are eight stamens with glabrous
filiform filaments and oblong anthers. Three of the stamens
closely 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, 7.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 otier. 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-
earp. 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

POLYGONACEE 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.

testa

g —nucellus
Reh gid @-4" aleurone

~ ——slarch
endosperm

Fic. 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, J’. 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 OF CROP PLANTS

needed. The notch-seeded buckwheat (F. emarginatum),
a form cultivated in northeastern India and China, is dis-
tinguished from the preceding by having the angles of the
smooth hull prolonged into wide, rounded wings.
Varieties.—Three varieties of common buckwheat are
grown in the United States: Japanese, silver hull, and com-
mon gray. They may be distinguished by the following
key:
Key To VARIETIES OF ComMMON 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-

POLYGONACE& 205

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., 1912.
STEVENS, N. E.: The Morphology of the Seed of Buckwheat. Bot. Gaz.,
53: 59-66, 1912.
Observations on Heterostylous Plants. Bot. Gaz., 53: 277-308, 1912.
Tsutsum1, OcHimurA: Studies on the Buckwheat. Bot. Mag. (Tokyo),
8: 288-291; 417-421, 1894.
Wit.iams, F. N.: Primary Characters in the Species of Rheum, 29: 292-295,
1891.

CHAPTER XXIII
CHENOPODIACEZ: (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 (Aériplex, 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

CHENOPODIACEE 297

are usually small, greenish, and bractless (Sarcobatus, grease-
wood), or bracteolate (Beta). They are perfect (Beta), pis-
tillate (Kochia), polygamous (Kochia), moncecious (Sar-
cobatus), or dicecious (Atriplex spp.) They are usually regu-
lar. There are no petals. The calyx is three- to five-lobed
or parted, rarely of one sepal (Monole pis), or is entirely want-
ing in the pistillate flowers of some genera (Airiplex). 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 fruit is a utricle (one- Fic. 117—A,
seeded fruit with a loose pericarp) with mem- eimai 2
branous, leathery, or thin pericarp. The annular embryo
of Beta.
seeds may possess an abundance of endo-
sperm (Bela, 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, Sercobatus (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 moneecious or dicecious.
Bractlets silky-hairy, Eurotia (winter sage).
Bractlets not silky-hairy.
Pistillate flowers without a calyx, Aériplex (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

CF.
> Li
es perianth

anther —

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

large, alternate, petioled, and. triangular-ovate or arrow-
shaped in outline. The flowers occur in axillary clusters.
They are dicecious. 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

CHENOPODIACEE 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) isa
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 orache (Aériplex hortensis). New Zealand
spinach or New Zealand ice plant, is a member of the family
Mesembryacee, 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 (Sfznacia) into four types er 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.

CHENOPODIACE 301

4. Leaf beets.
(a) Chard or Swiss chard.
(b) Ornamental or foliage beets.

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

SUGAR BEET

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

Root.—The “‘beet”’ itself is, for the most part, an enlarged
tap root. The ‘‘crown”’ of the beet is developed from
hypocotyl. The root part of the beet may be distinguished
from the hypocotyl portion (stem) by the two opposite, longi-
tudinal rows of secondary roots (Fig. 4). The tap root
extends almost straight downward, and the lower portion be-
comes small and thread-like and commonly reaches a depth
of 4 feet and often 6 or 7 feet. The lateral roots and
rootlets are very 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; these stems give rise
to flowering branches (Fig. 119).

302 BOTANY OF CROP PLANTS

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

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

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

CHENOPODIACEE 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

cal led

pa renc yee

large-celled
parenchyma

cJ -ring. of growth

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

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

304 BOTANY OF CROP PLANTS

sumed from this that it would be possible to find conspicuous
differences in the anatomical structure of beets varying 1 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

Fic. 121.—Diagram show- Fic. 122,—Sugar beet (Beta vulgaris).
ing distribution of sugar inan A, flowers grouped in the axil of a bract;
average sugar beet. (After B, cluster of flowers which fuse to forma
Molinari.) multiple germ beet ‘‘seed.”

sugar content. The sugar content decreases from a point
below the broadest portion of the root fo 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 4é 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

Fic. 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

20

306 BOTANY OF CROP PLANTS

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

Pollination and Fertilization.—The beet flower is protan-
drous. Shaw has shown that “self-fertilization”’ (autogamy)
does not take place, and that “close
fertilization”? (geitonogamy) is usu-
ally ineffective. He has also demon-
strated that thrips voluntarily travel
from plant to plant, and positively
assist in pollination of beet flowers.

Tha Bees are of little consequence in this

Fic. 124.—Diagram of process. Wind is the chief factor in
ree ee beet pollen dissemination.
ae a oo Fruit and Seed.—The ripened

Ores ee 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 elimina-
tion, to a large extent, of “thinning.” Townsend and
Rittue say that there is some indication that plants grown
from single-germ seeds produce a greater number of single
flowers than plants from multiple-germ seeds. It must be
borne in mind that the so-called “beet seed”’ is in reality a
fruit, that a multiple-germ seed consists of several one-
seeded fruits, and a single-germ seed of one one-seeded
fruit.

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

Seed Production.—The beet industry in the United States
has been dependent almost wholly upon Germany for its
supply of beet seed. However, in the last year or so, con-
siderable activity has been manifested in the growing of beet
seed at home, and as a result, we are now growing success-
fully large quantities of seed. Since the beet is a biennial,
it is necessary to store the roots of the first year, and set
them out the following season, in order to obtain seed. The
‘“‘mother beets” may be tested for their sugar content before
planting, and only those 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 seedling consists of a very short
hypocotyl which scarcely appears above ground, two rather
fleshy, glabrous, short-petioled, one-nerved cotyledons, and

308 BOTANY OF CROP PLANTS

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

Types of Sugar Beets.—There are two well-known and
common types 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.—The following analyses of sugar beets were
made by Headden.!

! German | Michigan | Colorado | Montana
beet, beet, beet, beet,
grams grams grams grams

Average weight trimmed......... ...... : 813.000 | 673.000 | 479.300
Water. cy ecnmasieenee nae pains | 74.550 78.000 75.800 | 74.603
Dry substance..................) 25.450 | 22.000! 24.200] 25.370
Sugar..............0...0.2...... 16.600! 15.300] 18.300] 18.240
Total ash...................... 1 0.800 0.701 0.820 2.680
PROtelny § ges. Scuba tance wees Gone & 0.706 0.769 0.543 0.436

Except in extreme cases, there seems to be little support for the statement
that the greater the weight the less the sugar content of the beet. The com-
position of the beet is affected by age, disease, fertilizers, insufficient food
supply, light, time of topping, rainfall, etc. The average sugar content of
American grown beets is about 15 percent. 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

1 Colorado Agri. Exp. Sta. Bull. 183.

CHENOPODIACEE 300

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 crystallization brought about
in vacuum evaporators. The material that comes from the
vacuum evaporators is a mixture of crystals and molasses.
This mixture (‘‘masscuite’’) is placed in centrigufal machines
lined with fine sieves; here the molasses is driven out and the
sugar retained. The sugar is next fed into the granulator,
where the crystals are separated from each other during the
drying process. The molasses from the first boiling is again
boiled, and further crystallization brought about.

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

310 BOTANY OF 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 qualities.

Types.—As to color, there are two main groups of garden
beets: (1) Flesh red (Early Blood Turnip, Eclipse, Egyptian,
Detroit, Dark Red); and, (2) Flesh yellow (Early Yellow

EUROPEAN
ALL OTHER RUSSIA 168%

COUNTRIES H.9 J

Fic. 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 delicate than that in later maturing
ones. The roots are boiled, pickled, or mixed in salads.
Considerable quantitites are canned, and in some cases the
common garden sorts are used for stock food.

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312 BOTANY OF CROP PLANTS

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

Fic. 127.—Chard or leaf beet (Beta vulgaris),

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

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 1 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 like spinach, and the petioles are served like
asparagus.

MANGEL-WURZELS OR MANGELS
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.

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

Types.—As to shape, there are four well-recognized types
of mangels (Fig. 128):

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

Globe, Orange Globe).
2. Tankard.—Varieties of this type have roots which are

314 BOTANY OF CROP PLANTS

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

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

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

Composition and,Uses.—The mangels vary in sugar con-
tent from 3 to 8 per cent., the Golden Tankard and Globes
having the highest percentage. Long varieties are relatively
low in sugar content but produce a greater tonnage per acre.
The water content varies from 85 to 92 per cent. Mangels
are being extensively grown for stock food. They are
one of the most important root crops. The root crops
include all plants whose underground vegetative parts, such
as rootstocks or roots, are utilized. Bulbs and tubers,
however, are usually excluded. Examples of root crops are
beets, mangels, turnips, carrots, rutabagas, sweet potatoes,
and artichokes. Root crops are used for human food and
also for forage. It must be kept in mind that all “root
crops” are not wholly roots, morphologically, but that in
some, such as the carrot, turnip, rttabaga, 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
Gorr, E. S.: Vegetables: Garden Beet. 6th Ann. Rept. N. Y. Agr. Exp.

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

CHENOPODIACEE 315

PRITCHARD, F. J.: Some Recent Investigations in Sugar-beet Breeding.
Bot. Gaz., 62 : 425-465, 1916.

RucceBerc, H.. Beitrage zur Anatomie 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 RitrvE, E. C.: The Development of Single-germ Beet
Seed. U.S. Dept. Agr. Bur. Plant Ind. Bull. 73: 1-23, 1905.

TownsEnp, C. O.: Single-germ Beet Seed. Jour. Hered., 6: 351-354, 1915.

CHAPTER XXIV
GROSSULARIACEZ (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. Asa 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. ror) in the bud. In a few cases, as the golden
currant (Ribes aureum), they are convolute (Fig. 101).

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

Fic. 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

318 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 placente, 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

creer -— vascular bundle
Of receptacie

—-receptacle

carpe!

vascul.
pe ene
~ovule cavit y

~splacenta

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

GROSSULARIACEZ 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 are,
for the most part, natives of temperate Europe, Asia, North America and the
Andes of South America.

Key To Important SpEcIES OF GENUS RIBES

Stems with one to three thorns below the clusters of leaves, often with nu-
merous scattered prickles on the branches, sometimes upon the fruit
also. Leaves plaited in the bud (Fig. 101) (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 prickleless; leaves plaited in bud (Fig. 101); 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. ror); racemes
several flowered; torus above much elongated, bright yellow. R. aureum
(Missouri, flowering, golden, or Buffalo currant).

320 BOTANY OF CROP PLANTS

CURRANTS

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

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

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

GROSSULARIACE 324

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 (Spherotheca mors-uv@).

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
21

322 BOTANY OF CROP PLANTS

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

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

CHAPTER XXV

CRUCIFERZ (Mustard Family)

This family is of world-wide distribution. There are in
the neighborhood of 2,000 species in 180 genera. The largest
number of genera and species is found in southern Europe

and Asia Minor. They are
found from low to high latitudes
and from low to high altitudes.

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

Stems, Leaves.— Most mus-
tards are herbaceous; a few are
woody. The sap is usually
watery and acrid. The leaves
are alternate, simple, and vari-
ously lobed or dissected. The
stipules are wanting.

Fic. 131.—Crucifere. Floral
diagram above; flower in median
longitudinal section below.

Inflorescence and Flowers.—The predominant type of
inflorescence is a terminal raceme; rarely the flowers are

solitary at the end of a scape.
323

The mustard flower is char-

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-

Fic. 132.—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

CRUCIFERZ 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 Crucifere
(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-like
fruit (Fig. 133), which is termed a silique jaye 133—Fruit
(Brassica) when long and slender, and a of cabbage (Bras-
silicle (Bursa). when short and broad. The one a dee
sides (valves) of the fruit separate at dehis- eae a
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 OF CROP PLANTS

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

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

Closely Related Families.—Members of the mustard family may be mis-
taken for those of the poppy family (Papaveracee) or caper family (Cappari-
dace@), 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).

CRUCIFERA 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 silique 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 the genus are for the most
part insect pollinated. It appears that both self- and cross-
pollination takes place.

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

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

Key To PRINCIPAL SPECIES oF GENUS BRASSICA

Leaves of flowering stem not clasping; annuals; sepals spreading.
Seeds small, reddish-brown; valves of silique one-nerved, B. nigra (black
mustard). :
Seeds large, pale yellow; valves of silique three-nerved, B. alba (white
mustard).

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.).

BRASSICA OLERACEA (Cabbages, etc.)

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

Fic. 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 1 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 34 to 1 inch in diameter,
and of a pale yellow color. The fruit is a smooth silique
often 3 or 4 inches long.

CRUCIFERE 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 CuLtivaTtep 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 collard).
Stem unbranched, the axillary buds developing into small heads (Tig. 136),
B. oleracea var. gemmifcra (Brussels sprouts).

Fic. 135.-—Kale (Brassica oleracea Fic. 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. botrytis (cauliflower, broccoli).

BRASSICA OLERACEA VAR. VIRIDIS (Fig. 135)

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 cauliflower, 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

CRUCIFERE 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 1 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.

yc

Fic. 137.—Common head cabbage (Brassica oleracea capitata). 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, earliness, etc. As grouped
here, the types may be distinguished as follows:

Key To Types orf 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 pickling 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 slightly 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. Asa 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

CRUCIFERE 333

lactic-acid species of bacteria on the sugar in the cabbage
juice. Ordinarily there is a maximum of about 1 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 Turnip-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 Va
and eaten like turnips or ruta- ‘
bagas. It is also a valuable ge
stock food; both the stems and Fic. 138.—Kohlrabi (Brassica
leaves are used for this purpose. GiEESERS Eatlotane).
Kohlrabi is chiefly grown as an early spring crop, less frequently
as a fall crop. It does not endure the heat of summer.

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

Fic. 139.—Cauliflower (Brassica oleracea botrytis). A, entire plant; B,
portion of ‘‘head."’

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

CRUCIFERE 335

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

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

Cauliflower and broccoli are both cool-season crops.

BRASSICA RAPA (Turmip)

Description— The common turnip is a biennial. The
first year a swollen 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 1 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 4%
inch in diameter and of the characteristic mustard type.
The fruit is 114 to 2 inches long, cylindrical, and tipped by a
short beak. The seeds are reddish brown in color, spHeeees
and number 15 to 25 in each silique.

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

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

336 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).

Fic. 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 Milan).
Spherical (Purple Top White Globe).

Root entirely red (Scarlet Kashmyr).

Flesh yellow.

Root entirely yellow (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).

CRUCIFERE 233

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, unlike 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

Fic. 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

22

338 BOTANY OF CROP PLANTS

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

BRASSICA NAPUS (Rape)

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

Fic. 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

CRUCIFERZ 339

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

BRASSICA NIGRA (Black or Brown Mustard)

Description. The black mustard is an annual herb 2 to
7 feet tall, and freely branching. The lower leaves are hairy
and deeply pinnatifid, with one large, terminal lobe and
two to four smaller, lateral ones; the lobes are coarsely
toothed. The upper leaves have much shorter petioles than
the lower, or they are entirely sessile, and the blades are
entire and oblong or lanceolate. The flowers are bright yel-
low. The pods are slender, four-sided, oppressed against the
stem, and measure about 14 inch or more in length. The
seeds are dark brown.

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

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

340 BOTANY OF CROP PLANTS

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

Related Species.—It is closely related to the white mustard which is de-
scribed hereinafter, and to Chinese or Indian mustard (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 x 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 lighter colored bristly pods, and its lighter colored and
larger seeds.

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

CRUCIFERZ 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-
nialherb. 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, 1 to 214 feet tall. This stem may be sparsely
pubescent with stiff hairs, especially below, or rarely gla-
brous throughout.

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

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

Fruit.—The pods are 1 to 1}4 inches long, two- to three-
seeded, fleshy, or corky with a spongy tissue separating the
seeds; the pods are not longitudinally grooved or promi-
nently constricted; they are capped by a long conic beak
which may equal or exceed the pod itself.

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

342 BOTANY OF CROP PLANTS

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

Geographical Distribution and Origin—-The common
radish is 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 raphanistrum, the wild radish or white
charlock, and a common weed throughout Europe, and also
adventive in the United States. He bases his opinion on his
own experiments which in brief were as follows: The seeds of
Raphanus raphanistrum, which has very woody and slender
roots, were planted and after five years of care there was
developed a type of root which was fleshy, large, and varying
in form and color. The roots developed had the flavor of our
garden radishes and were edible. In spite of the experiments
of Carriere, many botanists believe that white charlock is not
the projenitor of the radish. For example, it is known that
the garden radish long ago was a common plant in India,
China, and Japan. But Raphanus raphanisirum 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

CRUCIFERE 343

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

Raphanus sativus caudatus, the rat-tailed radish, an annual herb native to
South Asia, has a slender, twisted pod, 8 to 10 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, cauliflowers and beans. Early or
forcing radishes reach an edible size very soon, often in from
twenty to thirty days. In this group, belong such varieties
as French Breakfast, Early Scarlet Turnip, Scarlet Globe,
Long Scarlet Short Top, and White “‘Icicle.”

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

3. Winter Radishes—These have a compact and firm flesh
and keep well through the winter. The roots require several
months to reach maturity, often attaining a large size.
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

N

Fic. 143.—Types of radishes (Raphanus sativus). A, turnip-shaped; B,
globular; C, olive-shaped; D, half-long; E, long. (After Corbett.)

in elongated racemes; they have:spreading sepals, yellow or
white petals, and one tosixstamens. The siliques are short or
clongated, 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.

CRUCIFERE 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 beara short persistent style. In cultiva-
tion, the plant seldom produces seed, but is propagated by
root cuttings.

Geographical.—Horse-radish is a native of Europe. It is a common home

garden plant in the United States, and in some instances has escaped from
cultivation and become a troublesome weed.

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

RADICULA NASTURTIUM-AQUATICUM
(Water Cress)
Description.— This is a perennial, aquatic plant with long
floating or creeping stems which readily take root at the

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

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

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

CRUCIFERE 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
America.

References

CaRRIERE, E. A.. Une nouvelle
plante fourragere et econom-
ique. Journ. d’Agric. Prat.
Annee, 33, tome 11: 845-847,
1869.

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

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

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

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

CHAPTER XXVI .
ROSACEZ (Rose Family)

The Rosacee are well represented in North Temperate
climates. There are about 1,200 species within 65 genera.
The most important genera from the crop standpoint are
Rubus (raspberry, blackberry and dewberry), and Fragaria
(strawberry). Other genera of importance or of interest are
Spir@a, 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 Spirea,
terminal or axillary and solitary, racemose
or paniculate in Rubus, and corymbose or
racemose in the strawberry. It is interest-

Fic. 146.—Floral ing to note the great number of different

wee sorts of inflorescences in this one family, and

contrast it with the mustard family, in which

the raceme is the one prevailing type, or with the carrot

family in which the umbel is,. with the exception of one

genus, the only type, or with the sunflower family, all mem-
bers of which have a head inflorescence.

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

348

ROSACEZ 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

rim o
receptacle

nA

rece placle

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

Key To ImporTANT GENERA OF ROSACEZ

Fruit not inclosed in a hollow receptacle, i.e., the calyx not constricted over
the fruit.
Carpels becoming follicles, Spirea.
-Garpels 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, Fragaric (strawberry).
Receptacle not fleshy in fruit, Potentilla (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 Chamemorus, cloudberry, knotberry or

ROSACL At 3

on
a

mountain bramble). ‘hey are usually designated as
“brambles.”” The stems are, asa 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

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

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

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

352 BOTANY OF CROP PLANTS

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

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

Inflorescence.—The flowers are terminal or axillary, 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
1913, a shoot (cane) is sent up from the root. This bears
leaf buds entirely. In 1914, these lateral buds elongate, and
some of the resulting shoots bear inflorescences. The
shoots, developed in 1913, once having borne fruit in 1914, are
no longer useful. The cutting out of these useless shoots will
induce the development of new ones from the roots.

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

ROSACEE 353

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

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

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

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

Key To Groups oF Genus Rusvus

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-cluster 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 1 to 3 feet tall, very
thorny, R. cuneifolius (sand blackberry).
Lower surfaces of leaves pubescent but not whitish; plants 1 to 8 feet
tall, thorny, R. nigrobaccus var. 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.

ROSACEE 355

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

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

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

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

DEWBERRIES

These differ from blackberries in their trailing habit,
cymose inflorescences, and propagation by tips. They
have received the name “trailing blackberry.” There are

356 BOTANY OF CROP PLANTS

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

Key TO PRINCIPAL SPECIES OF DEWBERRIES

Leaves evergreen, R. trivialis (southern dewberry).
Leaves deciduous.
Buds tipped by the united ends of the sepals, forming a spine; flower clus-
ters forking into two or three parts, R. invisus (northern dewberry).
Buds not tipped by the united ends of the sepals to form a spine.
Both hermaphrodite and pistillate plants; leaflets coarsely toothed, R.
vilifolius (western dewberry).
Plants all perfect; leaflets finely toothed, R. villosus (northern dewberry).

Rubus trivialis.—These are trailing shrubs, with stout, hooked prickles and
bristles on the stems, and with upright branches 3 to 9 inches tall. The leaves
are trifoliate,-petioled, and with oval, leathery, serrate, evergreen leaflets.
The inflorescences are one- to five-flowered. The flowers are large, white,
and have petals that are much longer than the sepals. The fruit is black,
and up torinchlong. 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. The leaflets are large
and coarsely and simply dentate. The erect peduncles are elongated. The
large flowers are on long pedicels; flower buds are tipped by the united ends
of the sepals. The species is reported by Bailey as growing wild from New
York to Alabama and east to Kansas and Missouri. The chief varieties are
Bartel and Mammoth.

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

Rubus villosus.—The plants are robust, with smooth stems and large,
thick leaves, which have three to seven oval or ovate, long-pointed and sharply
double-toothed leaflets. The inflorescences are one to three-flowered, leafy,
and cymose. The fruit is globular, and has a few, shining-black, and sweet
drupelets. This is the common dewberry of the Northern States; it 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 (variely roribaccus) isa more robust form with large wedge-obovate,
jagged leaflets, and large flowers on Jong pedicels.

ROSACEZ 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 stiff and erect; fruit produced more or less continuously throughou
the season, R. ideus (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 10 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 idwus.—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. ideus 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 2 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 1 to 114 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 microphyllus and Cuthbert, a variety of Rubus strigosus.

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 are usually formed after

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

ROSACE 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.
Practically all roots are within the first foot of soil.

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

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

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

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

N
NA rim of receptacle
“fleshy receptacle

wv
Stamens”

Fic. 151.—Strawberry (Fragaria chiloensis). Median lengthwise section of
flower. xX 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 calyx is five-parted, with five bracteoles
(epicalyx) below, that are persistent in the fruit. There
are five obovate, short-clawed petals, attached to the rim of

ROSACEE 361

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

Fertilization, and Development of the Fruit.— Strawberries
are protogynous, that is, the pistils of a flower mature before
its stamens. Hence cross-fertilization is secured; and this
usually by insects. Non-fertilization or incomplete 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 reality stem structure. These bundles send
off side branches into the cortex, and some of them extend
to the achenes. The persistent calyx and epicalyx, and

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

DB a" \ x)
g ) |
——-cortex of,

¥) recepta

\— medulla o
b receptacle

|
|
|
!

Facepface J
K |

calyx lobe

Fic. 152.—Strawberry (Fragaria chiloensis). A, ‘‘fruit’’ in median length-
wise section, X 24; B, single achene, x 20.

attachment of fruit to receptacle. The achenes are com-
monly termed ‘‘seeds.”’

Geographical.—The genus Fragaria possesses about eighteen species most
of which are natives of the north temperate zone; a number are found in
the Andes of South America. Strawberries are cultivated in all parts of
the United States.

ROSACEE 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 californica and F. glauca.

The early settlers in the Eastern States cultivated the
common wild strawberry (Fragaria virginiana) which they
found growing in their fields. But few cultivated varieties
belong to it. Varieties of the wild strawberry of Europe
’ (Fragaria vesca) have also been cultivated in America, but
only to a slight extent. These varieties are the Everbearing
or Perpetual strawberries.

Hence, the varieties of strawberries in America fall into
three groups, as follows:

1. Chilean group from Fragaria chiloensis.

2. Scarlet or Virginian group from Fragaria virginiana.

3. Perpetual or European group from Fragaria vesca.

These three species may be distinguished by the following
key:

Key To PriIncrpaAL 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, Jate (Aroma, Gandy, Chesapeake, Splendid).
Growers distinguish between commercial varieties and those
for home consumption. A good commercial variety should
be hardy, very productive, of good color, firm, and of good
size and form. Among good commercial varieties, may be
mentioned Bederwood, Excelsior, Jucunda, Dunlap, Captian
Jack, Splendid, and Parson’s. Beauty. Such varieties as
Warfield, Ridgeway, Marshall, Aroma, and Chesapeake are
grown for home use.

Origin of New Varieties.—Strawberries seldom come true
to seed; hence it is possible to secure new varieties by plant-

ROSACE 365

ing seed. When a desirable variation appears, propagate it
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

Bartey, 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, grt.

BunyarD, E. A.: The History and Development of the Strawberry. Jour.
Hort. Soc., 39: 541-552, 1914.

Corsett, L. C.: Strawberries. U.S. Dept. Agr. Farmers’ Bull. 198: 1-24,
1904.

CHAPTER XXVII
POMACEZ (Apple Family)

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

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

Flowers.—The flowers (Fig. 157) are regular, perfect, and
usually with a concave or cup-shaped receptacle or torus to
which is attached a five-lobed or five-toothed calyx, five sepa-
rate petals, numerous distinct stamens and a one- to five-
celled ovary. The ovary is ordinarily five-celled, and the
carpels are wholly or partly united. The carpels vary in
texture from parchment-like (Malus, etc.) to bony (Crate-
gus and Cotoneaster). The number of styles varies in the
different genera: generally three in Sorbus, two to five in
Malus (usually five), mostly five in Pyrus (pear), two to five
in Amelanchier, one to five in Crategus (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

POMACE 367

Geographical.—The family is of wide geographical distribution, there being
close to 225 species within about 20 genera. Most of the species occur in
north temperate or boreal regions.

Key To Important GENERA OF POMACEE

Ripe carpels bony, Crategus (thorn-apple, haw, hawthorn).
Ripe carpels papery or leathery.
Leaves compound, Sorbus (mountain ash).
Leaves simple.
Ovules one in each cavity, Amelqnchier (service-berry, June-berry).
Ovules (usually) two in each cavity.
Flesh of the pome with grit-cells, Pyrus (pear).
Flesh of the pome without grit-cells, Malus (apples 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. Asa rule, a shoot that
has once started to bear flowers continues to do so, making
but a very short growth of wood each year. Such a shoot is
marked by the closely crowded leaf scars, terminal-bud scars,
and flower and fruit scars. The position of a fruit is usually
marked by a large circular scar surrounded by a number of
smaller ones of the same shape. The smaller ones represent
scars made by flowers or fruit that failed to develop. It has
been recorded generally, particularly for Eastern orchards,
that the fruit buds in apples are always terminal, and further-

368 BOTANY OF CROP PLANTS

¥

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

Fic. 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

POMACEZ

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 fguit 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.

Tt 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

Fic. 154.—
Mature Jona-
than apples
from axillary
flower btds.
(After Pad-
dock and
Whipple.)

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

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

POMACE 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, z.e., in order
from without to the inside.

Fic. 155.—Diagram showing the development of apple. Dotted area repre-
sents pith. Notdrawntoscale. (After Kraus, Oregon Agr. Exp. Sta.)

The primordia of stamens appear in three cycles, those of
the outer usually being laid down first (Fig. 156). The carpel
primordia appear within the central portion of the cup-shaped
torus. There are five of these surrounding a small central
cavity, which is formed by a lack of growth at the center of
the torus: Hence there is no common placenta, but each
carpel has its two separate placentas, which in “‘open-cored”’
pomes may become closely connected. These facts will be
considered again in the account of fruit development.

It is thus shown by the studies of Kraus that calyx lobes,
petals, stamens, and carpels are all outgrowths of the urn-
shaped receptacle.

372 BOTANY OF CROP PLANTS

Pollination and. Fertilization—The literature on this
subject is extensive. Cross-pollination is the rule and
self-pollination the exception in the apple and pear. Ex-
periments have shown that the wind aids but little in cross-
pollination, and that insects, chiefly the honey bee, are
relatively more important. The bee is attracted to the
flowers by the nectar which is produced rather abundantly.

Fic. 156.—Floral diagram of apple (Malus sylvestris). Note that the sta-
mens are in three distinct whorls. (After Kraus.)

Self-sterility and Self-fertility——-Many apples and pears
are self-sterile, that is, will not fertilize their own pistils.
In such cases, pollen from another variety will usually result
in fertilization. Self-sterility and self-fertility probably
vary with different climatic conditions. In Oregon, Lewis
and Vincent found that the Spitzenburg is self-sterile but
capable of being fertilized with pollen from a number of other
varieties, such as Yellow Newton, Arkansas Black, Jonathan,
and Baldwin. Evidently, the mutual affinities of apple
varieties must be considered in setting out an orchard. It
would not be well to plant solid blocks of Spitzenburg, for
example. It should be alternated with rows of some one of

POMACEE 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

He
e styles“ \

7
rim of receptacle

Fic. 157-—Apple (Malus sylvestris). Median longitudinal section of
flower.

impresses its characteristics upon the fruit. It is difficult to
understand how foreign pollen could have any considerable
effect of this kind. The flesh of the apple is receptacle for the
most part. The sperm nuclei of the pollen, of course, do not
come into contact with the nuclei of the receptacle cells. It is
altogether possible, however, that uniformity of crop, percent-
age of set, and size of fruit are immediately affected by
strange pollen.

374 BOTANY OF CROP PLANTS

Parthenocarpy.—As a general rule, lack of fertilization of
the ovules in the ovary is followed by the shedding of the
blossoms; the ovary fails to develop completely if a good
number of its ovules are not 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 100 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 Development.— Mor phology—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

POMACEZ 375

in the ripening process. The content of sucrose (cane sugar)
increases steadily in the ripening process up to a maximum
and then suddenly decreases. There is a rapid decrease of
starch throughout the entire period. Invert sugar (a mix-
ture of glucose and fructose) increases throughout the ripen-
ing period while the total sugar increases up to the date when
starch entirely disappears, after which time it fluctuates
slightly. Malic acid, which gives the fruit its sourness,
gradually becomes less and less. Ripening takes place in
two stages. The first stage involves that portion of the fruit
within the core line (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 line. The second stage of the ripening proc-
ess involves the region outside the core line. At first,
streaks free of starch appear in the midst of this area. Soon
the middle portion of the area becomes free of starch. There
is a gradual increase of this starch-free area, the last regions
to ripen being V-shaped areas radiating from the vascular
bundles as seen in cross-section. Furthermore, anatomical
changes take place in ripening. The middle lamelle 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
lamella; those varieties that are comparatively very mealy
have correspondingly weak lamella. When a cell divides
into two, the common primary wall between them becomes
the middle lamella of the thicker wall formed by the deposi-
tion of material from both protoplasts. Hence in the mature
cell wall, the primary or first-formed wall appears as a defi-
nite layer between the added layers. Separation of two ad-
jacent cells naturally takes place along this middle line.

BOTANY OF CROP PLANTS

376

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POMACEZ.- 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. Asa
tule, 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 anetwork.
Many observers have wrongly considered all tissue from
parchment-like tissue, surrounding the seed cavities, out to
vascular ring, inclusive, as carpellary, whereas others have
considered only the parchment-like tissue as carpellary.

The ten primary vascular bundles are related in their
development with the carpels, as is shown by the fact that
when six carpels occur there are twelve bundles instead of
ten, and when there are four carpels, eight bundles.

Longitudinal Section of Fruit.—In longitudinal section
(Fig. 158), the flesh is seen to be separated into two parts by
a distinct line, the ‘‘core line.’”” The core line marks the
junction of pith and cortex of the-receptacle. The primary
vascular bundles of the torus follow the core 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: OF CROP PLANTS

be seen in a line at right angles to an axis from stem end to
calyx end. Form terminology includes such terms as round,
oblate, conical, ovate, oblong, elliptical, etc. The flower
stem persists in the fruit. The depression about the stem
is termed the cavity. It varies in shape and depth in the
different varieties. At the opposite end from the cavity is
the basin. This also varies in character and is of taxonomic
value in the classification of fruits. The remains of the
calyx are persistent within the basin of the common apple.
In the pure Siberian Crabs, the calyx is deciduous, while in
hybrid forms of Siberian Crabs and in the common apple
it is partly deciduous. The dried stamens and styles may
be seen within the calyx lobes.

The stamens may be basal, situated near the base of the
calyx tube; median, near the middle; or marginal, near the
outer edge. The calyx tube itself varies in shape from con-
ical to funnel-shaped. The calyx segments, five in number,
vary in their arrangement in the mature fruit. They may
be divergent, that is, reflexed, erect convergent, when their
margins touch, flat convergent, when they are flat and close
the tube, and connivent, when they are overlapping. In a
median transverse section, the “‘cells’ in different varieties
vary in shape and relation to the axis of the apple. They
may be “open” or “‘closed,’’ axile or abaxile. When the
walls extend to the axis, the cells are axile, and when they
are distant from the axis, and unsymmetrical, they are abaxile.
When the core line meets inside the calyx tube, the core is
said to be meeting; if near the calyx tube, it is clasping.
The core outline varies in shape. There are usually two
seeds in each cell cavity; however, there may be more than
two or fewer or sometimes none at all. They vary in size
and color.

POMACEE 379

Key TO PRINCIPAL SPECIES OF MALUS

Calyx deciduous from the apex of fruit.
Leaves conduplicate in the bud (Fig. ror); petioles thick, usually about 1
inch long; flowers rose-colored, Malus floribunda (flowering crab).
Leaves convolute in the bud (Fig. 101); petioles slender, usually about 2 to
3 inches long; flowers white or very light rose-colored, Malus baccata
(Siberian crab).
Calyx persistent on the fruit.
' Leaves glabrous, at least when mature.
Leaves prominently lobed, thin, Malus coronaria (American crab-
apple).
Leaves toothed, but not lobed, thick, Malus angustifolia (narrow-
leaved crab-apple).
Leaves persistently pubescent or tomentose beneath.
Leaves narrowed at base; pomes small, 1 to 114 inches in diameter.
Pedicels slender, 1 to 134 inches long, Malus coensis (Western crab-
apple).
Pedicels stout, 14 to 1 inch long, Malus soulardii (Soulard crab-
apple). ;
Leaves rounded or subcordate at base; pomes large, z to 4 inches in
diameter Malus sylvestris (common apple).

Malus floribunda, Flowering Crab—This is a shrub or small tree, often
thorny. The leaves are conduplicate in the bud, the flowers abundant,
showy, and rose-red, the fruit red, about the size of a pea, and on slender
stalks. It is highly ornamental, and flowers in early spring. It isa 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 14 to 34 inch in diameter, yellow or red, firm and translucent.
The species occurs in many forms. The orchard fruits known as “‘crab-
apples,” are believed to be hybrids between this and the common apple, M.
sylvestris. The Siberian crab grows wild from Siberia to Manchuria and the
Himalaya region. : ;

M. angustifolia, Narrow-leaved Crab-apple.—It is a low tree with small,
narrow, lanceolate leaves, few-flowered cymes, fragrant pink flowers, and
fruit about 1 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 1 to 134 inches
in diameter, somewhat flattened endwise, greenish-yellow, waxy, fragrant, and

380 BOTANY OF CROP PLANTS

Fic. 159,—Leaves of Malus species. A and B, western crab (M. ioensis);
C, flowering crab (M. floribunda); D, narrow-leaf crab (M. angustifolia); E,
Soulard crab (M. soulardi); F, common apple (Wealthy) (M. sylvestris); G,
American crab (M. coronaria); H, Siberian crab (M. baccata). x 4.

POMACEE 381

rich in malic acid. 1t 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, IIli-
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 leaves similar to those of M. ioensis, in close clusters on short,
densely woolly pedicels; the fruit is larger and of better flavor than that of M.
iensis. 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-Cochnah], 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 im toto or with modifications. He divided the
varieties into seven classes, and these into orders. These
classes are as follows: Ribbed apples, Rose apples, Ram-

382 BOTANY OF CROP PLANTS

bours, 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 Ralls-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 | Total Total Invert , Cane |Acidsas :
gravity solids sugar sugar sugar | H2SOq' Tannin

Summer varieties | x.049 | 12.33 9-53 | 5.85 | 3.50, 0.33 | 0.040
Autumn varieties | 1.054 | 13.76 ; 10.66 | 6.93 | 3.53 | 0.36 | 0.069
Winter varieties. .| 1.056 | 14.29 | 11.43 | 7.04 | 4.16 | 0.41 | 0.050
Crab-apples......| 1 15.69 | 11.71 | 8.08 | 3.45 0.50 | 0.122

For vinegar-making, a high sugar content is desirable. A
common notion is that acid or “‘tartar’’ apples are better for
vinegar-making than those lowin acid. The amount of acetic
acid in a vinegar, which is the important test of its quality,
is dependent upon the amount of sugar in the juice (cider)
and not upon the acid. The sour taste of apples is due to the
malic acid present. So-called ‘‘sweet apples” do not neces-

POMACEE 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: (1) 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 1915 there
were produced 230,010,000 bushels of apples in this country,
at an average farm price per bushel of 74.6 cents. The ten
leading States in the order of their production were New York,
Missouri, Ohio, Pennsylvania, Illinois, Virginia, Kentucky,
Indiana, Iowa and Michigan.

PYRUS (Pear)

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

“stone cells
“parenchyma cells

Fic. 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. 16c).

The two most common species of Pyrus are Pyrus communis,
the common pear, and Pyrus serotina culia, 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.

POMACEE 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 Jeaves are ovate, elliptic, and
finely toothed. The flowers are in simple terminal cymes;
the pedicels are 2 to 3 inches long, and appear with the leaves;
the petals are five in number, rounded, short-clawed, and
usually white; the sepals are persistent; the styles are distinct
to the base.

Fruit.—The fruit varies in shape, usually tapering to the
base; the flesh is with grit cells (Fig. 160) (groups of stone cells.
imbedded in parenchyma).

Geographical.—The common pear is probably a native of southern Europe
and Asia. In many localities, it has escaped from cultivation. There are

numerous cultivated varieties. The pear thrives best in the northern half of
the United States.

PYRUS SEROTINA CULTA (Sand, Japanese, or Chinese Pear)

This is a strong-growing tree with broad-ovate, long-
pointed leaves that are very sharply toothed. The large
flowers appear before the leaves. The fruit is hard and
russet-like, keeps well, and has a deciduous calyx.

The tree is a native of China. Chinese Sand, Madame von-

25

386 BOTANY OF CROP PLANTS

Siebold, Mikado, and Japanese Sand are a few of the varieties
grown’in the United States. It is also often used to hybrid-
ize.with our common pear, the Kieffer variety being the
best-known one resulting from such a cross.

Self-sterility in Pears—The work of Fletcher has pointed
out the reasons for the barrenness of many pear orchards.
Much of this is due to self-sterility, that is, the inability of
the pollen of a variety to fertilize the ovules in the pistils of.
that variety. It has been frequently observed in many
portions of the country that when a certain variety of pear, as
well as other fruits, was planted thickly, there was often pro-
nounced self-sterility. This is particularly true, it seems, of
Bartlett and Kieffer pears. Fletcher obtained the following
average results, under Virginia conditions, in self-fertilizing
Bartlett, and in crossing with a number of varieties (in the
table, the last mentioned variety of a cross furnished the
pollen):

Pollinations Av. number of Av. weight of
blossoms set mature fruit,

ounces
Bartlett X Bartlett........ rin 513 2.00
Bartlett X Kieffer. ....... 1in 10 3.00
Bartlett X Anjou......... lin 7 3.75
Bartlett X Lawrence...... tin 9 3.50
Bartlett X Duchess....... rin 10 3.50

The following table shows similar relations in the case of
Kieffer pears: ;

Pollinations Av. number of
blossoms set
Kieffer X Kieffer...................00.. 1 in 253
Kieffer X Bartlett...................... tin 5
Kieffer X Le Conte.......... cial, Ata tin 7
Kieffer X Lawrence..................... rin 6
Kieffer X Duchess.......... ca ipeaaeh 2h, tin 5
Kieffer X Anjou...............2.0.2004 rin 4
Kieffer X Clairgeau................00.. tin 3
Kieffer: <: Garber‘ cco clon eita cs eras 3 tin 7

POMACEZ 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.t When pears are grafted on the more slowly growing
roots of the quince, the stock in this case retards the growth
of the pear, and dwarfing results. The common quince
used in Angers and the varieties ordinarily dwarfed are
Angouleme, Bartlett, Anjou, and Louise Bonne. Dwarfing
appears to improve the quality of the fruit.

1If 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. oblonga (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 14 inch long.

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

POMACEE 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

ALwoop, WILLIAM B., and Davipson, R. J.: The Chemical Coniposition of
Apples and Cider. U.S. Dept. Agr. Bur. Chem. Bull. 88: 7-18, 1904.
Beacz, S. A., Booru, N. O., and Taytor, O. M.: The Apples of New York.

22d Ann. Rept. N. Y. Agr. Exp. Sta., vol. 1: 1-409; vol. 2: 1-360, 1903.

BIcELow, W. D., Gore, H. C., and Howarp, B.J.: Studies on Apples. U-S.

Dept. Agr. Bur. Chem. Bull. 94: 1-100, 1905.

Brack, CAROLINE A.: The Nature of the Inflorescence and Fruit of Pyrus

malus. Mem. N. Y. Bot. Gardens, 6: 519-547, 1916.

Braprorp, F. C.: The Pollination of the Pomaceous Fruits. IJ. Fruit-bud

Development of the Apple. Ore. Agr. Exp. Sta. Bull. 129: 1-16, 1915.

Brooxs, Cuas.: The Fruit Spot of Apples. Bull. Torrey Bot. Club, 35: 423-

456, 1908, (includes notes on structure of fruit).

Bupp, J. L., and Hansen, N. E.. American Horticultural Manual. Part IJ,

Systematic Pomology. John Wiley & Sons, ro1r.

BuTLerR, O.: On the Cause of Alternate Bearing inthe Apple. Bull. Torrey

Bot. Club, 44: 85-95, 1917.

CHITTENDEN, F. J.: Pollination in Orchards. III. Self-fruitfulness and Self-

sterility in Apples. Jour. Hort. Soc., 39: 615-628, 1914.

DECAISNE, JoSEPH: Memoire sur la famille des Pomacees. Nouvelles Ar-

chives du Museum, X, pp. 113-192 (Paris), 1875.

Le jardin fruitier du museum, un iconographie de touts les especes et
varietes d’arbres fruitiers cultives dans cet etablissement. Firmin
Didot Freres.

Drinxkarp, A. W.: Fruit-bud Formation and Development. Rept. Vir. Agr.

Exp. Sta., 1909-1910: 159-205, IQII.

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, IQII.

Gorr, E.S.: The Origin and Early Development of the Flowers in the Cherry,

Plum, Apple and Pear. 16th 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. 18th Ann. Rept. Wis. Agr. Exp. Sta. 304-
316, 1901.

Origin and Development of the Apple Blossom. Am. Gard., 22: 330 and
346-347, Igor.

Garpner, V. R., Wacness, J. R., and YeacrEr, 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.

Harpy, J. A., and A. F.: Traité de la taille des arbres fruitiers, ed. 12, 123,
Paris.

Heprick, V. P.: Dwarf Apples. N. Y. Agr. Exp. Sta. Bull. 406: 341-368,
Ig15.

Kraus, E.J.: The Pollination of the Pomaceous Fruits. I. Gross Morphology
of the Apple. Ore. Agr. Exp. Sta. Res. Bull. I, pt. I: 1-12, 1913.

The Study of Fruit Buds in Oregon. Ore. Agr. Exp. Sta. Bull. 130: 12-21,
IQIS.

Variation of Internal Structure of Apple Varieties. Ore. Agr. Exp. Sta.
Bull. 135: 3-42, 1916.

- Kraus, E. J., and Rarston, 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.

McAtrineg, 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.
Pappock, W. and Wurpete, O. B.: Fruit Growing in Arid Regions. Mac-

Millan Co., 1910.

Pickett, B. S.: Factors Influencing the Formation of Fruit Buds in Apple
Trees. Trans. Mass. Hort. Soc., pt. I: 57-72, 1913.

SANDSTEN, E. P.: Some Conditions Which Influence the Germination and
Fertility of Pollen. Wis. Agr. Exp. Sta. Research Bull. 4: 149-172,
1909.

SHaw, J. K.: The Technical Description of Apples. Mass. Agr. Exp. Sta.
Bull. 159: 73-90, 1914. :

Waite, W. B.: The Pollination of Pear Flowers. U.S. Dept. Agr. Div. Veg.
Path. and Phys. Bull. 5: 1-110, 1894.

West, G. H.: The Pollination of Apples and Pears. Trans. Kans. State
Hort. Soc., 32: 38-50, 1912.

CHAPTER XXVIII
DRUPACEZ (Plum Family)

Habit, Stems.—Representatives of the plum family are
trees or shrubs. The bark exudes a gum, and the leaves,
bark, and seeds are bitter, and contain prussic acid. Many
cases of poisoning have been
recorded from eating the seeds
of peach and bitter almond, and
it is also known that stock is
poisoned from eating the leaves
of wild cherries. The glucoside,
amygdalin, acted on by emulsin,
an enzyme, in the presence of
water is changed to prussic acid,
grape sugar, and benzaldehyde.
Prussic acid is deadly poisonous
even in small amounts.

Leaves.—The leaves are
alternate, petioled and com-
monly finely toothed. The
teeth and petiole are often
glandular (Fig. 161); the stipules 6
are early deciduous. ee

Flowers.—The perfect, regu- of the leaf considerably enlarged,
lar flowers (Fig. 162) are ™ Ei
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

39r

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

one
rim of receptacle
~style

Fic. 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

DRUPACEZ 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.

Fic. 164.—Median lengthwise section of young cherry fruit (drupe).

Fruit.—The fruit is a drupe (Fig. 164), that is, one with
a single seed surrounded by a stony endocarp, fleshy meso-
carp, and an outer skin or exocarp (epicarp). However, if
one examines the young ovary of a Prunus flower he will 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, almond, peach and
apricot. These main groups may be distinguished by the
following key:

Key to Main Groves oF Genus PRuNuUS

Stone smooth.
Flowers clustered; fruit glabrous.

Fruit large, usually grooved, covered with a bloom; stalk short; stone
usually compressed, longer than broad; Jeaves convolute in the bud
(Fig. 101), Plums.

Fruit small, usually not grooved, not covered with a bloom; stalk long;
stone usually globular; leaves conduplicate in the bud (Fig. 101),
Cherries.

Flowers solitary or in two’s; fruit velvety at first, A pricots.
Stone pitted or furrowed.

Flesh soft, thick, juicy, Peaches.

Flesh hard, thin, dry, Almonds.

The genus has about go species, nearly all of which occur
north of the equator; they are widely distributed in both
eastern and western hemispheres. Most species are con-
fined to the temperate zone. The evergreen cherries include
a group found in the tropics and subtropics.

PLUMS

Stems.—The plums are shrubs or small trees. The
different species vary considerably in bark and twig charac-
ters. The bark of southern forms is lighter in color than
that of those growing in the north. Plums have a tendency

DRUPACEZ

395

to produce spurs (Fig. 165). Flower buds are, as a rule, on
these spurs, one spur bearing from 2 to 20 buds. The spur
may terminate in a leaf bud. However, in most plums, true

terminal buds are seldom formed. In
such cases, if the last lateral bud is a
branch bud, this continues the growth
of the branch in a straight line. The
line between the two seasons’ growths
is not as sharp, in this case, as when a
terminal bud develops. If the last
lateral bud is a flower bud, the twig
usually dies back to the lateral branch
developed from the last branch bud.
In all 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.
IOI).

Inflorescence.—The flower buds of
the plum, unlike 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

Fic. 165.—Twig of
Domestica plum
(Prunus domestica).
(After Paddock and
Whipple.)

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).

396 BOTANY OF -CROP PLANTS

On its edge, are arranged five sepals, five petals, and fifteen
to twenty stamens. There is a single pistil bearing one style
and one stigma. The pistil is at the bottom of the recep-
tacle. There are two ovules in the young ovary; one of them
aborts during maturation of the fruit.

Fertilization—Many of the plums are practically self-
sterile. The native plums exhibit the greatest self-sterility;
this is due to the impotency of the pollen when used on the
stigma of the same flower. Japanese and domestic plums are
less self-sterile than native species. In some cases, not only
are pistils developed that are so weak as to fail even if polli-
nated, but some flowers do not form pistils. Again, pistils and
stamens of the same flower often mature at different times.
Usually, the pistils mature first. Rarely, the opposite is
the case. Hence it is seen that cross-fertilization is very nec-
essary in plum orchards, but not only cross-fertilization be-
tween different trees of the same variety but between dif-
ferent varieties. It is reported by Hendrickson that French
and sugar prunes in California set a very light crop unless a
large number of bees are present in the orchard at the time
of blooming. They appear to be self-sterile to some extent.
Imperial prune trees that were enclosed in a tent from which
all insects were excluded set no fruit. Itseems that, with the
Imperial prune, fruit is not set unless pollen is brought from
other trees. It is distinctly self-sterile. All Prunus species
are insect-pollinated for the most part.

Fruit.—After 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): (1)
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

DRUPACEE 307

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, rg11; and Wight, W. F., “Native American
Species of Prunus,’’ Bull. 179, B. P. L., 1915.

Key TO PRINCIPAL SPECIES OF PLUMS *

Flowers in clusters of one or two (three in P. triflora), OLD WorLD PLums.
Shoots and pedicels pubescent.

Fruits large, more than 1 inch in diameter, variable in shape, often
compressed; tree large; stamens about 30, P. domestica.

Fruits small, less than 1 inch in diameter, uniformly oval or ovoid;
tree small, compact; stamens about 25, P. insititta.

Shoots glabrous or soon becoming so, pedicels glabrous.
Flowers mostly single, P. cerasifera.
Flowers in threes, P. triflora.

Flowers in clusters of three or more, rarely two, AMERICAN PLuMs.

Leaf serrations glandless, acute; calyx lobes entire, glabrous on the outer,
pubescent on the inner surface, not glandular, P. americana.

Leaf serrations glandular (at least when they first unfold), rounded or ob-

tuse; calyx lobes glandular (except in P. 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. nigra.

Leaves narrow, ovate, ovate-lanceolate, the margin rarely doubly serrate;
flowers 8 to 15 millimeters broad; calyx rarely reddish, the lobes entire,
either glandular or glandless.

Leaves thick, slightly lustrous on upper surface; veins conspicuous below;
margin coarsely and irregularly serrate, P. hortulana.

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-elliptical; the upper
surface is smooth, the lower often finely hairy, the margins
coarsely toothed, and the teeth often glandular. The flowers
usually appear after the leaves, sometimes with them. The
fruit is generally globular, the skin varies in color, the flesh
is yellowish, and the stone free or clinging.

This is the best known and most widely distributed species
of plums. It has been cultivated for 2,000 years, originally
coming from about the Caucasus Mountains. The first
colonists brought varieties of this species to North America.
There are now over 950 varieties of Domestic plums grown
in this country. These have been divided into a number of
groups, largely based upon fruit characteristics. These
groups are as follows:

1. Green Gages (Reine Claude).—These are low trees with
dark bark which cracks deeply, with leaves doubly toothed,
fruit relatively small, round, mostly green or golden, and of
excellent quality. The stone is either free or clinging.
Important varieties are Reine Claude, Bavay, Spaulding,
Yellow Gage, Washington, etc.

2. Prunes.—A prune is any plum that can be cured without
removing the pit. All plums with a large percentage of sugar
make good prunes. The fruit is large, oval, usually com-
pressed, blue or purple, and with a firm, greenish, yellow, or
golden flesh, and free stone. Prunes are raised on the Pacific
Coast. The industry there has become a large one. Im-
portant varieties are Italian, German, Agen, Tragedy, Ten-
nant, Sugar, Giant, Pacific, and Ungarish.

Preparation of Prunes.—In the preparation of prunes, the

DRUPACEE 399

plums are first cleaned, and their skins ruptured to permit of
more rapid drying. Usually, they are dipped into boiling
water or hot lye, which not only cleans but also cracks the
skin. They are then dried in the open sun, or in drying
sheds where artificial heat may be utilized. After drying,
the prunes are allowed to “‘sweat”’ for two or three weeks.
They are then graded and ‘“‘glossed”’ or finished by heating
in steam or immersing in salted boiling water, glycerine or
fruit juice. This gives the surface of the prunes a shiny
appearance, and also sterilizes the exterior.

3. Peridrigon Plums —This is a prune plum grown only
in France.

4. Yellow Egg Plums—The fruit of these is large, in fact
the largest of plums, long-oval, and has a yellow or purple
skin, and yellow flesh. Well-known varieties are Yellow
Egg, Red Magnum Bonum, Golden Drop, and Monroe.

5. Imperatrice Plums—These are medium-sized, dark
blue plums, with thick skin, firm flesh, and clinging stones.
Such varieties as Ickworth, Arch Duke, Monarch, Shipper,
Arctic, etc., belong to this group.

6. Lombard Plums.—This group includes the reddish or
mottled varieties of Domestic plums. Lombard, Bradshaw,
Victoria, Pond, and Duane are well-known varieties.

Prunus insititia—This is a small tree not over 25 feet high
with small ovate or obovate, finely toothed leaves which are
usually glandular; both surfaces of the leaves are slightly
hairy. The flowers are usually in lateral, umbellate clusters.
The fruit is globular or oval, small, usually bluish black or
golden yellow, and has yellow flesh, and a clinging or free
stone.

Varieties of this species are hardy and thrifty. The species
has been in cultivation over 2,000 years, but in all that time
has shown but little variation. Insititia plums rank second

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
quality.

4. St. Juliens—This is a name applied to a group of plums
resembling the Damsons. They were formerly used in this
country as stocks.

Prunus cerasifera.—These are the cherry or Myrobalan plums. They are
hardy, thrifty varieties, free from disease, readily adaptable and most suitable
for hybridizing. The trees are small, bloom profusely, and bear a small,
round, cherry-like plum from 14 to 1 inch in diameter. They are adapted
to ornamental usage. They are also used as stocks upon which to bud
other plums.

Prunus 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 Valley, Americans
domesticated the native American plum. Varieties of this species are hardy.
The American plum tree is usually small, with rough, shaggy bark. The
fruit is reddish or yellowish. Altogether, there are about 260 varieties of
the americana. Waugh finds that they often bear defective pistils or
stamens, or that they are often protandrous or protogynous. From his
observations, he recommends some provisions for cross-fertilization when
planting americanas.

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

DRUPACE 4o1

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.

Prunus angustifolia—The Chickasaw plum is a small] tree, 6 to 10 feet
high, sometimes shrubby. The fruit is small, almost globular, flesh yellow,
and of good quality. It ranges from Delaware to Louisiana and westward
to Arkansas and Texas. Its varieties do well in the Southern States.

The two subspecies, watsoni and varians, have varieties of some horti-
cultural value, such as Purple Panhandle, African, Clark, Emerson, etc.

CHERRIES

Description.—The cher-
ries resemble plums in
many respects. The bark
of the cherry separates in
rings. The flower buds are
usually 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 fig. 166.—Spur of sour cherry (Prunus
terminates the short shoot. cexasue)-

The flower buds bear only flowers and no leaves (except very

rudimentary ones which persist but for a short time). There
26

402 BOTANY OF CROP PLANTS

are from two to five blossoms, usually two, in each bud. ‘The
flowers are in umbels, as a rule. The flowers and fruit of
cherries are, morphologically, similar to those of plums.

The leading commercial varieties of cherries grown in
California have been shown to be self-sterile. It is altogether
possible that sterility in cherries is widely spread.

Groups of Cherries.—According to Bailey the principal
cultivated cherries are from two species, Prunus avium, the
sweet cherries, and Prunus cerasus, the sour cherries.

PRUNUS AVIUM (Sweet Cherry)

Description——The sweet cherry is a tall tree, strong-grow-
ing, long-lived, and frequently attains a diameter of 1 foot
or more. The bark is gray-brown, the outer layer often
being roughened; lenticels are inconspicuous. The leaves
are thick, oval, ovate or obovate, 4 to 12 centimeters long,
abruptly short-acuminate, irregularly and coarsely toothed,
or doubly so, green and smooth above, lighter beneath,
slightly hairy on the veins, more or less drooping, and with
long slender petioles. Flowers appear with the leaves, in
lateral, sessile umbels; the flower pedicels are 3 to 6 centi-
meters long; the petals are white, and the stamens 35 or 36.
Self-sterility has been reported in the sweet cherry orchards
of the Northwest. The fruit is variously colored, spherical
to heart-shaped, with flesh soft or hard, usually sweet, and
with the skin adherent to the flesh.

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:

1. Mazzards—tThe fruit is small, and varies in shape and
color. Mahaleb and mazzard stocks are the two common

DRUPACEZ 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” pug. 367—Twig
readily from the root. The bark is gray- of sweet cherry

x ¥ (Prunus avium).
brown and quite smooth; lenticels are con- (After Paddock
spicuous. The leaves are thick, ovate or 0”? Whipple.)
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

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 Philippe, and
the Morello.

F ; Other Species of Cherries.—The species of cher-
1G. 168.—Twig of Fe : : : és
sour cherry (Prunus les native to America are of little horticultural
cerasus). (After Pad- importance. Chief of these are P. pennsylvanica,
dock and Whipple.) 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 mahaleb, a native of Europe and Asia, is very extensively used in
this country as a stock for all sweet and sour cherries. It is an excellent
dwarfing stock.

Uses.—Both sour and sweet cherries are used as a dessert
fruit, and in the making of pies. The bulk of the cherries

DRUPACEE 405

grown for canning purposes are sour red sorts, and are pro-
duced in New York, Michigan, Wisconsin, and California.
Maraschinos are sweet cherries, most of which are imported
from Italy and Spain. A Californian variety, Napoleon, is
also used to some extent for this purpose. Recent investiga-
tions point to the conclusion that a number of commercial
products may be obtained from cherry pits and cherry juice,
two by-products of the cherry industry. The fixed oil
expressed from the fresh kernels is much like almond oil, and
can be utilized in similar ways. Also, the volatile oil is quite
similar to bitter-almond oil, and can be used in the same way.
The pressed cake, that which remains after the oils are re-
moved, may be ground into a meal and used as a feeding
stuff. The waste cherry juice can be changed into syrup,
jelly and alcohol.

APRICOTS

Stems.—The common apricot varieties belong to the
species Prunus armeniaca. The trees are small, round-
topped, and resemble the peach tree. As in the plums, true
terminal buds are seldom formed. Lateral branch buds and
flower buds are found together in the axils of leaves (Fig.
169). Except for a few rudimentary leaves, the fruit buds
bear only flowers. Normally, there is but one flower (some-
times two) in a bud; they appear before the leaves. The
flower buds, which are lateral, occur singly at nodes; often
three buds are developed in the axil of a leaf, the central
one being a branch bud, while the two laterals are flower
buds. However, not all branch buds on a twig are accom-
panied by flower buds. The vigor of the tree and twigs, and
pruning methods will determine the position of the latter, to
some extent. In strong-growing twigs, the flower buds are
rather near the tip of a year’s growth; on twigs of moderate

406 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 cntire
length. However, not all
the flower buds are formed
on the long shoots. Many
are developed on_ ex-
tremely short spurs, but
always axillary; usually
the flower buds are single
in such short growths.
Leaves.—These are usu-
ally ovate, often somewhat
heart-shaped at the base,
abruptly short-acuminate,
smooth above, - slightly
hairy beneath, finely
toothed, on glandular
petioles, and convolute in
vernation.
Inflorescence and
Flowers.—The flowers are
solitary or in pairs, pink-
ish, sessile or nearly so.
Morphologically, the
flowers are similar to those
of plum, cherry and other

Fic. 169.—Twigs of apricot (Prunus
armeniaca). (After Paddock and Prunus spp.

i 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

DRUPACEA

407

parts of the flower are cut off by a basal ring of growth, as

described in the plums.

DistributionThe 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. dasycar pa, 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

Fic. 170.—Twigs
of peach (Prunus
persica). (After Pad-
dock and Whipple.)

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

408 BOTANY OF CROP PLANTS

a branch bud (Fig. 170). In this respect, they are similar
to the apricot.

Leaves.—These are conduplicate (Fig. ror) in the bud,
elliptic to lanceolate or oblong, and taper toward either end;
they are finely and sharply toothed, and on stout petioles.

Inflorescence and Flowers.—The flowers are normally
solitary in the axils of leaves and appear before the leaves;
they are large, pink, fragrant, and showy.

Fruit.—The fruit is subglobular, grooved slightly on one
side, has velvety skin, and hard flesh which may be free
(freestones) or adherent (clingstones) to the stone. The
stone is compressed, pointed, and pitted. The seed is of
the shape of an almond, aromatic, and slightly bitter.

Geographical.—The peach is a native of Asia, probably China. It was in-
troduced into Europe at a very early date, coming by way of Persia. This
fact accounts for the specific name, persica, and common name, peach.
The tree is now cultivated in temperate regions. Occasionally it is escaped
from cultivation, especially throughout our Northern and Middle States..

Types of Peaches.—The first system of classification of
peaches was worked out by Onderdonk, of Texas. He
divides the varieties of peaches into five classes or races,
based primarily upon the country in which they originated,
hence upon their range of adaptability.

1. Peen-to Race-——The stone is almost spherical (Fig.
171, C, D), somewhat compressed at the end, and with small
and round corrugations; the fruit (of original peen-to) is much
flattened; the skin is white, blotched with red, and flesh
white; the stone is free or cling. It is adapted to subtropical
regions. Varieties: Angel, Clara, Hall, Waldo.

2. South China Race (‘“Honey” Group).—The stone is
oval (Fig. 171, B), and its corrugations 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 499

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.

Fic. 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, cling, semi-cling or free; the fruit is large, almost glob-
ular, and its flesh is fine-grained and juicy. It has a wide
range of adaptability. Varieties: Belle, Lee Ray, Superb.
Elberta and several other varieties are considered crosses
between the North China and Persian races.

410 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
like the preceding. The common varieties of peaches grown
in northern orchards belong to this race. Varieties: Crothers,
Foster, Late Crawford, Reeves, Salway, Walker.

In addition to the above, the Nectarine should be added
as a variety of peach. It differs from the common peach in
that its fruit is smaller, the skin is smoother, and the leaves
are commonly more prominently toothed. There are both
freestone and clingstone nectarines. It is known that
nectarines appear on peach trees and peaches on nectarine
trees. Such fruits that thus appear are evidently ‘bud
variants.”

Uses, and Production of Peaches in the United States.—
The fruit is used largely as a dessert, both fresh, dried and
canned. Peaches are usually pitted before they are dried.
The seeds of the peach, as well as those of almond, apricot
and plums, contain both fixed and volatile oils, which are of
commercial value.

There are peach interests of commercial importance in a
large proportion of the States. The total output of peaches
for the country in 1915 was 64,218,000 bushels, which were
sold at an average farm price of 81.1 cents. California led
in production, with 9,768,000 bushels. The other nine lead-
ing States, in the order of their output, were Arkansas,
Georgia, Texas, Missouri, Alabama, Kansas, Tennessee,
Oklahoma and Ohio.

ALMONDS

Description.—The common almond is Prunus amygdalus
(Amygdalus communis). The tree is much like the peach in
shape and size. The flower buds are axillary along with
branch buds, as in the peach and apricot. The Jeaves are

DRUPACEE AII

lanceolate, firm, shining, and finely toothed. The flowers are
normally solitary and appear before the leaves. They are
large, pink, and showy. Many varieties are sterile without
cross-fertilization. The drupe is much compressed. The
mesocarp (portion corresponding to the flesh of peach or
plum) is leathery and tough and separates readily at maturity
from the stone (endocarp and seed). The “unshelled”’
almond of commerce consists of the thin, pitted, light-colored
endocarp, within which is the seed or ‘‘kernel.”

The common almond is a native of Asia.

Types of Almonds.—The two general types or races of
common almonds are the bitter and the sweet. The difference
is in the composition and taste of the kernel. The sweet or
edible almonds consist of two groups: Hard-shell and soft-
shell. The latter are of the greater economic importance.

In addition to the common almonds, Prunus amygdalus,
there are a number of dwarf forms which are grown mostly
as ornamentals.

Uses.—Almonds are grown for the nuts which are used
directly as a food. Almond oil finds use in the manufacture
of flavoring extracts. The seeds are also a source of prussic
acid.

Almond Oil.—Most of the so-called oil of almonds is
derived from the seeds of the apricot; almond and peach
seeds also furnish a considerable quantity. The oils from
these three sources are very nearly the same. In the process
of extracting almond oil, the seeds are ground, subjected to
great hydraulic pressure to remove the undesirable fatty
oil, and the residue ground again, fermented, and distilled
with steam. The distillate is almond oil and hydrocyanic
acid. This latter, deadly poisonous substance is removed by
treating the mixture with lime and copperas.

412 BOTANY OF CROP PLANTS

References

Baitry, L. H: Fourth Report on Japanese Plums. Cornell Exp. Sta. Bull.
175: 131-160, 1899.

Barwey, L. H., and Powert, G. H.: Cherries. Cornell Agr. Exp. Sta. Bull.
98: 471-500, 1895.

Ear, 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.

GorTHE, R.: Uber die Klassification der Pfirsichsorten. Gartenflora, 55:
169-182, 1907.

Goutp, H. P.: Growing Peaches: Varieties and Classification. U.S. Dept.
Agr. Farmers’ Bull. 633: 1-18, 1914.

Heprick, V. P.: The Cherries of New York. 22d Ann. Rept. N. Y. Agr.
Exp. Sta., vol. 2, part 2: 1-371, 1915.

The Plums of New York. 18th Ann. Rept. N. Y. Agr. Exp. Sta., vol. 3,
part 2: 1-616, rg11.

The Blooming Season of Hardy Fruits. N. Y. Agr. Exp. Sta. Bull. 407:
367-391, 1915.

Henpricxson, A. H.: The Common Honey Bee as an Agent in Prune
Pollination. Calif. Agr. Exp. Sta. Bull. 174: 127-132, 1916.

Hume, Harowp 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.

Powe LL, G. Harotp: 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.

QuaintTanceE, 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. ‘

Wicut, W. F.: Systematic Botany of the Plum as Related to the Breeding
of New Varieties. Ann. Rept. Am. Breeders’ Assn., 8: 488-497, 1912.

The Varieties of Plums Derived from Native American species. U.S. Dept.
Agr. Bull. 172: 1-44, 1915.
Native American Species of Prunus. U.S. Dept. Agr. Bull. 179: 1-75, 1915.

CHAPTER XXIX
LEGUMINOS£ (Pea Family)

The pea family is one of wide geographical distribution,
occurring both in temperate and warm 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
Leguminose. Probably no family is of greater agricultural
importance than this one, unless it is the Graminee. 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-like structures. These organisms
have the power of fixing free nitrogen of the air. That is,
free nitrogen gas from the soil air is taken by the organism

413

414 BOTANY OF CROP PLANTS

and, together with other chemical elemients, 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.—Leguminosz are either annual, biennial or peren-
nial; and are either herbs (peas, beans, alfalfa, etc.), shrubs
(Genista, dye-weed or green-weed), or trees (Robinia and
Gleditsia, locusts), and a very few are vines (Vicia spp.,
vetches).

Leaves.—These are alternate on the stems, stipulate, and
mostly compound. They are generally odd-pinnate, that
is, a leaflet terminates the rachis of the leaf, as in Robinia
(locust), Astragalus (vetches) and Aragallus (loco) ; sometimes
they are even-pinnate, that is, terminated by a tendril or
bristle, as in Vicia (vetch) and Lathyrus (wild and sweet
peas); or they may be trifoliate, as in clovers, or digitate, as
in Thermopsis (buckbean).

Inflorescence.—The flowers are nearly always arranged in
racemes (pea), sometimes in a head (clovers), or spike-like
raceme (alfalfa), or spike (Glycyrrhiza, licorice).

Flowers.—These are irregular (Fig. 172); they have a
butterfly-like shape, and for this reason, flowers of the pea
type are often spoken of as “‘papilionaceous.” The calyx
is normally four- to five-toothed or cleft, the teeth or lobes
being equal or unequal. The petals are usually five in
number, a broad upper one (standard, banner or vexillum),

LEGUMINOS 415

two lateral ones (wings or ale), 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.

a
me)

c

epee lee eazay)
: ee Q

Fic. 172.—Flower of Leguminose. 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 A straga-
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
légume 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 (Hedysarez),

416 BOTANY OF CROP PLANTS

the fruit is a loment, that is, a jointed indehiscent legume,
constricted between the seeds. The style, calyx, and
withered stamens are often partly persistent in the fruit.

Seeds.—The seeds are usually without endosperm; the
cotyledons are thick and full of food.

The seeds of legumes are noted for their great longevity.
Some have been known to retain their viability for 150 to
250 years. This is correlated with their very hard, imper-
meable seed coats. So-called “hard seeds” are very com-
mon in the pea family. Such seeds are tardy in their ger-
mination, either under laboratory or field conditions. As a
rule, only a portion of a crop of seeds is hard, although in
some cases the whole crop may be hard. It is claimed that a
larger percentage of hard seeds is produced in dry climates
or when ripening takes place under dry seasonal conditions
than in moist climates or moist seasons. The permeability
of leguminous seeds can be increased by “‘scarifying,”
that is, passing them through a machine that abrases the
surfaces. The ordinary alfalfa huller is effective as an
abraser, as is shown by the experiments of Harrington who
found that alfalfa seed, grown under a variety of soil and
climatic conditions, had about go per cent. of hard seeds if
hulled by hand and only about 20 per cent. if hulled by
machine.

Key To PRINCIPAL GENERA OF LEGUMINOSZ

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). Pe
Style flattened, bearded along the inner side (Fig. 173, B), Lathyrus
(vetchling).
Plants without tendril-bearing leaves.
Leaves palmately three-foliate (Fig. 183), Trifolium (clover).
Leaves pinnately three-foliate, rarely five- to seven-foliate (Fig. 182).

LEGUMINOSE 417

Flowers small, many in a cluster.
Flowers in slender, spike-like racemes, Melilotus (sweet clover).
Flowers in heads or short spikes, Medicago (a)falfa 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-
ee eee
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 thé 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

418 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 cr lavender; seeds angular, gray-
brown, gray-green, gray-yellow or gray speckled with fine spots of various
colors; leaf axils pigmented; comparatively hardy Pisum sativum (field

pea).

Garden Peas--The common garden pea can be divided
into two groups: Shelling peas, and edible-podded or sugar
peas. Jn 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
uwrinkled-seeded. Each of these is divided into (1) tall climb-
ing, (2) half-dwarf, and (3) dwarf varieties, and each of the
latter three groups into white-seeded and green-seeded sorts.
The sugar peas occur in both tall, half-dwarf, and dwarf
forms.

Period of Maturing—As a general rule, the earliest sorts
of peas have smooth, round seeds, while the late sorts have

LEGUMINOS 419

wrinkled seeds. Smooth-seeded varieties are hardier than
wrinkled-seed varieties. This is not invariably the case,
however. Furthermore, dwarf and medium-sized forms
are early, while tall varieties are late. Green garden peas

Fic. 174.—Pea pods showing types and range of variation. A, extra early
dwarf wrinkled pea, American Wonder; B, medium early wrinkled pea,
Nott’s Excelsior; C, main crop smooth pea, Marrowfat. (After Corbett.)

are sometimes classified as to their time of maturing into
early, medium, and late or main crop. First of all, Alaska,
and American Wonder are examples of early sorts, McLeans,
Advancer, and Pride of Market of medium sorts, while
among late-maturing crops are such varieties as Telephone,
Telegraph and White Marrow Fat.

420 BOTANY OF CROP PLANTS

Field or Canadian Field Pcas—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.

TR ccc ORES

Sra: sion Pio nti i = eae oe 4

Fic. 175.—Pea pods showing types and range of variation. D, French can-
ning type smooth pea, French Canner; E, large podded wrinkled pea, Pride of
Market; F, fleshy or edible podded pea, Melting Sugar. (After Corbett.)

Field peas are successfully grown only in those regions with
a cool growing season, in fact, they will withstand quite
heavy frosts. High temperatures accompanied by high
relative humidity are decidedly injurious. Excellent crops
are grown at 7,000 to 8,000 feet in the San Luis Valley of
Colorado. They do well on most types of soil.

LEGUMINOS AS 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.

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 seedling, are
common objects of study
in general botanical
courses,

Geographical and Species.—
Members of the genus Phaseolus
are tropical and warm-country

Bie. -4ge.—Cammen due heen plants. According to Britton and
(Phaseolus vulgaris). A, spiral keel; B, Brown, there are close to 180
entire flower. X 2. 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), Jack bean (Cana-
valia ensiformis), locust bean (Ceratonia siligna) and hyacinth bean, bonavist
or lablab (Dolichos lablab).

LEGUMINOSE 423

The adjuki bean (Phaseolus angularis) and mung bean (Phaseolus aureus)
are now grown to some extent in this country.

Key To PRINCIPAL SPECIES OF PHASEOLUS

Roots tuberous or much thickened, P. multiflorus (scarlet runner bean).
Roots fibrous.
Seeds flat or flat-oval in cross-section, P. Junalus (Sieva and Lima beans).
Seeds mostly circular, but sometimes flat in cross-section, P. vulgaris
(kidney bean).

PHASEOLUS MULTIFLORUS (Scarlet Runner Bean, Dutch Case-
knife Bean, Flowering Bean, or Painted Lady)

These are perennials which usually have tall, climbing
stems and pinnately trifoliate leaves. The large and showy
flowers are scarlet (scarlet runner), or white (Dutch case-

Fic. 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 climb-
ing. The leaves are pinnately trifoliate, the leaflets varying
from narrowly lanceolate to ovate. The flowers are small,
and in axillary racemes. The pods are usually broad and
flat, and have flattened, variously colored beans.

The native home of these beans is tropical South America.
They require higher temperatures than the varieties of
Phaseolus vulgaris.

Classifications of Types of Lima Beans.—There are two
general types of Limas, as follows: (1) 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

Phaseolus lunatus (Sieva, Civet, or Carolina beans).
Plants bush (Henderson’s Bush Lima).
Plants pole (Small White Lima, Florida Butter).
Phaseolus lunatus var. macrocar pus (true Limas).
Seeds very flat and veiny; pods broad and flat, with tip not prominent
leaflets broad, not ovate, Flat-seeded Limas.
Plants bush (Burpee’s Dwarf Lima).
Plants pole (King of the Garden).

LEGUMINOSZ 425

Fic. 179.—Types of Lima beans. A, Potato Lima, pole; B, Sieva type, pole;
C, large, flat Lima, dwarf; D, Sieva type, dwarf. (Modified after Corbett.)

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 5g inch
across the wing, and are white, yellowish, or blue-purple.
The slender pods vary in shape, and have kidney-shaped
seeds.

This species is thought to be a native of tropical America.
The cultivated varieties thrive best where the growing
season is warm.

There are, according to Tracy, 145 varieties of kidney
beans in America. These are usually divided into two large
subdivisions, pole and bush. These in turn each possess
green-podded and wax-podded sorts. The bush beans are
often grouped together 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 climbing or trailing
herbaceous vines. The Jeaves are pinnate, tendril-bearing,

1 For a detailed classification of American varieties of beans see Bull. 109,
Bureau of Plant Industry, by W. W. Tracy.

LEGUMINOSZ

and with half-sagittate or entire
stipules. The flowers are blue,
violet, yellowish, or white, and
in axillary racemes. The calyx
tube is oblique, and its teeth or
lobes are about equal, or the
two upper ones somewhat longer.
The standard is notched at the
tip, and the wings are attached
to the curved keel. The stamens
are diadelphous (nine and one),
or monadelphous below, and
have filiform filaments. The
sessile or stipitate ovary has
numerous ovules and a slender
style with a tuft or ring of hairs
at its summit (Fig. 173, A).
The pod is flat.

Geographical.—There are more than
100 species of Vicia, of wide geograph-
ical distribution. There are about 20
wild species in the United States.

Key To ImporTANT SPECIES OF VICIA

Plants erect, smooth, or only slightly
hairy, seldom tendril-bearing; flowers
whitish with dark blue spots on each
wing, V.fabz (broad or Windsor bean).

Plants weak, usually hairy, tendril-
bearing; flowers purplish.

Leaves rounded at tip; flowers many,
in long one-sided racemes (Fig.
182), V. villosa (hairy vetch).

Leaves truncate at tip; flowers few,
usually two in each leaf axil, V.
sativa (vetch).

‘Bush; 12,

427

aol)

Fic. 180.—Types of bean seeds.
1, Broad Windsor; 2, White
Narrow Field; 3, Dutch Case
Knife Pole; 4, White Dutch Run-
ner Pole; 5, Grenells Stringless
Green Pod; 6, Long Yellow Six
Weeks; 7, Long White Pole Lima;
8, Powell’s Prolific Pole; 9, Dreer's
Pole Lima; 10, Florida Butter
Pole Lima; 11, Yellow Cranberry
Horticultural Wax;
13, Red Mexican; 14, French
Kidney. (Modified after Tracy,
U.S, Dept. Agri.)

428 BOTANY OF CROP PLANTS

Less Common Species.—There are a number of other Vicia spp. that are
cultivated to some extent, as follows: Narrow-leaved vetch (Vicia angustifolia)
is a native of the eastern United States, and is grown somewhat in Georgia

Fic. 181.—Broad or Windsor bean (Vicia faba).

asahaycrop. Black bitter vetch (Vicia ervilia) is an Asiatic species, cultivated
somewhat as a winter green-manure crop in California. Purple vetch (Vicia
atropurpurea) resembles hairy vetch from which it differs, however, in being
smooth, It is cultivated on the Pacific Coast and in the South. Scarlet

LEGUMINOSZ 429

vetch (Vicia fulgens), Narbonne velch (Vicia narbonnensis) and woolly podded
velch (Vicia dasycar pa) 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-
tilized. The hairy pods have four or five smooth, globular,
gray or marbled seeds. The Willamette Valley, Oregon,
produces a large proportion of the common vetch seed in the
United States. Vetch seed loses its viability very rapidly
after about the third year. The plant is a native of Europe.

430 BOTANY OF CROP PLANTS

It has become naturalized in many parts of the United States,
occurring in fields and waste places. Common vetch is
sown either as a winter or spring annual. If the winters are
severe it is planted in the spring. This is the practice in the
Northern States. However, in the south, where the winters
are mild, it is planted in the fall. It is adapted to a light
soil. It is intolerant of a poorly drained soil. The poorer
soils of the East, deficient in lime, will support a fair crop.
There are numerous varieties of the common vetch. Spring
and winter varieties are recognized. The white or pearl vetch
has white flowers and seeds.

Uses.—Common vetch is grown in the old country, and to
an increasing extent in United States, as a hay crop. When
grown for this purpose it should be cut when in bloom. The
seeds are sometimes made into a flour. The species is also
being recommended as a cover crop for orchards, and as a
green manure.

VICIA 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-fertilization is necessary for the
normal production of seeds. Bees are chief agents in the
dissemination of pollen. The pods are smooth, pale in color,
and contain two to eight small, globular black seeds. The
cotyledons remain underground at germination, as is the
case in the common garden and field pea. Hairy vetch is a

LEGUMINOSE 431

native of Europe and Asia. It is much hardier than common
vetch, and consequently can be grown at yhigher latitudes.
Moreover, it is more drought-resistant and tolerant offalkali.

Fic. 182.—Hairy vetch (Vicia villosa).

Hot summer weather is very harmful to its growth. It is
frequently planted on light, sandy soils, where it may be
plowed under as a green manure.

432 BOTANY OF CROP PLANTS

The plant has a variety of uses: hay, pasturage, cover
crop, silage, and green manure. It is usually cut for hay
about the time the first pods are full grown. The quality
of the hay decreases after this period.

LATHYRUS (Vetching, Wild Pea)

This genus resembles Vicia. The leaflets are broader, as
a rule, however, the flowers are larger, and the stigma is
hairy along the inner side (Fig. 173, B).

There are over 100 species of Lathyrus, natives of the
Northern Hemisphere and of South America. There are
numerous wild sorts in the United States. The two most
common species are Lathyrus odoratus; the common sweet
pea, and Lathyrus latifolius, the everlasting or perennial pea.
Lathyrus odoratus is an annual, bearing two to four flowers
on a peduncle, and pods 4 to 5 inches long. The following
Lathyrus species are of forage value and are now planted to
some extent in this country: L. tingitanus (Tangier pea),
L. cicera (flat-podded pea) and L. ochrus (ochrus).

TRIFOLIUM (Clover)

Generic Description.—Representatives of this group are
annual (crimson clover) or perennial (white clover) herbs
with palmately trifoliate (hence the name, Trifolium) leaves
(Fig. 183), the stipules of which are adnate to the petiole.
The inflorescence is a dense spike or head. The flowers
vary in color. The calyx is persistent, its teeth nearly
equal, and usually bristle-form. The corolla is also persist-
ent, sometimes grown fast to the tube of filaments. The
stamens are diadelphous (nine and one). The ovary is sessile
or stipitate, and few-ovuled. The pods are small, mem-
branaceous, mostly one-seeded (rarely more), indehiscent or
opening circularly. The seeds are small and kidney-shaped.

LEGUMINOS& 433

Geographical.— ‘There are close to 300 species of Trifolium, most of which
occur in the north temperate regions; a few, however, also occur in South
America and South Africa. They are distributed from low to high altitudes.
Besides those given in the following key, two others, T. suaveolens (Shaftal
or Persian clover) and 7. alexandrinum (Berseem) are grown to some extent
in the United States.

KEY TO PRINCIPAL SPECIES OF TRIFOLIUM

Flowers in spike-like heads, much longer than thick, T. 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), 7. 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.
28

434 BOTANY OF CROP PLANTS

Geographical, and Uses.—White clover has become dis-
tributed throughout the greater part of temperate North
America, Europe, and Asia. It is common in lawns, pas-
tures, and meadows, and is an important ingredient of lawn
grass mixtures. The only distinct agricultural variety is
Ladino clover (Trifolium repens latum). It is larger than
ordinary white clover, and less resistant to cold.

Environmental Relations.—White clover will withstand
greater temperature extremes than either red clover or alsike
clover. It is naturally suited to cool, moist regions. It is
more tolerant of shade than red and alsike clovers.

TRIFOLIUM HYBRIDUM (Alsike, Alsatian, or Swedish clover)

Description.—Alsike is an erect, branching, rather stout,
almost glabrous perennial, 1 to 3 feet tall. Its life period
is from four to six years. There are many secondary roots
which soon become as large as the main tap root. The
leaves are long and have greenish veins, long taper-pointed
stipules (Fig. 183, A), and obovate leaflets. The plant is more
leafy than red clover. The plant is usually cut for hay when
in full bloom. The flowering heads are on long peduncles
which arise from leaf axils. The flowers are pedicelled, and
white or pinkish. The pods are two- to four-seeded. The
seeds lose their viability rapidly after the second year.

Geographical, and Uses.—Alsike clover is a native of
Europe. It has been introduced into this country for agri-
cultural purposes and has escaped from cultivation, often
being found in fields and waste. places. It is not a hybrid
between white clover and red clover, as formerly thought.
The plant is grown in the same manner and for the same
purposes as red clover. The plant is very hardy, more so
than red clover, and is quite frequently mixed with timothy

LEGUMINOS 435

for planting at high altitudes and latitudes. It is prized as
a honey plant.

TRIFOLIUM INCARNATUM (Crimson, Scarlet, or 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

Fic. 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-like head (Fig. 184).
The flowers are bright crimson (rarely white, yellow, rose or
variegated) and showy. The seed is shiny when fresh "and
pinkish in color.

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 life period is a varietal
character. The average is about three years. It develops
from a strong fap 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 1 pound of root to 2 pounds
of plant above ground. This means that the clover crop
leaves considerable organic matter in the soil.

Leaves.—The leaves are of the clover type, with hairy-
margined leaflets and large conspicuously purple-veined
‘stipules. The leaflets often bear a pale spot in the center.

Inflorescence and Flowers.—The terminal inflorescences
are ovate (Fig. 184). Each inflorescence has from 35 to 150
purple-rose flowers. The second crop usually has more flowers

LEGUMINOS 437

per head than the first crop. The flowers are of the ordinary
pea type, except that the petals are united at their bases and
to the staminal tube to form a corolla-tube about }4 inch
long.

Fic. 184.—-Crimson clover (Trifolium incarnatum), on left; common red
clover (T. pratense), on right.

Fruit—The ovary develops into a capsule, bearing one
seed. There are two ovules in each ovary, but only one, as
a rule, matures into a seed. Infertile ovules are quite com-

438 BOTANY OF CROP PLANTS

mon in red clover, the larger percentage usually being in
the first crop. This is probably one of the chief reasons why
the second crop of clover is more commonly used for seed.
An additional advantage in harvesting the second crop for
seed rather than the first is that the farmer is able to get two
crops in a season, for if the first crop is allowed to seed, there
is insufficient food supply, and in some instances a season too
short, for the development of a vigorous second growth. In
addition to the reason given above for the
relatively light yield of seed in the first crop,
it is claimed that pollinating insects are not
abundant enough, and that the plant is occu-
pied with the production of new shoots rather
than reproductive activity. In general, a
rank-growing plant is not a good seed producer.
as gle When the capsule is maturc, the stylar end
clover (Trifo- separates from the basal part by an irregular
Sat ee nee 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 yellow, or mixed yellow and violet in
color.

Pollination—Red clover flowers are protandrous. The
work of Westgate and Coe establishes the fact that “‘red
clover flowers must be cross-pollinated in order to set seed
on a commercial basis.” The pollen must come from a
separate plant, for even when taken from flowers of the same
plant, the percentage of seed set is very small. The bumble-
bee (Bombus) is the most important insect visitor of the red
clover. It is capable of pollinating 30 to 35 flowers a minute.
Honey bees are also efficient pollinators. When the bumble-
bee lights on the clover head and inserts its proboscis into
the staminal tube, its weight presses down on the keel and

LEGUMINOSE 439

wings of the flower, from which nectar is being taken, thus
forcing out the stigma and anthers up against the bee’s head.
The stigma becomes dusted with pollen from another flower
and the anthers open, leaving pollen on the under side of
the bee’s head. The flower parts return to their original
position when the bee leaves the flower. Nectar sought by
the bee is secreted at the bases of the stamens, and collects
in the staminal tube.

Geographical.—The species is a native of Eurasia. It has become natural-
ized in the United States, occurring commonly in the fields and meadows
throughout most of our area.

Environmental Relations.—Red clover attains its best

growth in humid sections of the country, and where the
‘summer and winter temperatures are not extreme. Un-
like alfalfa, dry atmospheric conditions are detrimental to
red clover; but like alfalfa it requires lime in the soil. More-
over, it is intolerant of a poorly drained soil and of much
shade.

Mammoth Clover.—This clover, sometimes known as
perennial clover, sapling clover, pea-vine clover, and bull
clover, is a form of the ordinary Trifolium pratense; as
compared with the latter, mammoth clover matures later,
has a more highly branching tap-root, longer pedicels, and
solid stems. It is known as Trifolium pratense perenne.

Uses.—Common red clover is:one of our most prized
forage and hay crops; it is also raised to some extent as a
green-manure and cover crop. Its importance as a crop in
the United States may be judged from the fact that the total
acreage is about five times that of alfalfa. It is adapted to
the humid sections of the country. The highest percentage
of digestible substances occurs in the plant just before full
bloom. The plant soon becomes tough and fibrous after
the blooming period.

440 BOTANY OF CROP PLANTS

“pie

Fic. 186.—A vigorous alfalfa plant showing the ‘‘crown”’ from which
arise the numerous shoots. (After Headden, Colo. Agr, Exp. Sta.)

LEGUMINOSZ 441

TRIFOLIUM MEDIUM (Zigzag, Medium Red, White, Mammoth or
Meadow Clover)

This is a perennial clover resembling red clover (7. 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 Fic. 187.—Seed and pod
the petiole, and the leaflets com- % aaa heated sativa).
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

442 BOTANY OF CROP PLANTS

ovary is sessile or short-stipitate, and several- or rarely one-
ovuled; it has a subulate (awl-shaped), and smooth style.
The pods (Fig. 187) are curved or spirally twisted, veiny or
spiny, and indehiscent.

Geographical.—There are a number of species of Medi-
cago, all of which are native to the eastern hemisphere. They
naturally range from Eastern Asia to Southern Africa.
There are seven perennial species of Medicago, and about 37
annual species, one of which, yellow trefoil (Medicago lupu-
lina), has a biennial or possibly perennial form. The non-
perennial species are commonly known as “bur clovers.”
They will grow naturally as winter annuals.

Key to PrincipAL SPECIES OF MEDICAGO

Perennial, erect-growing plants; flowers violet, Medicago sativa (alfalfa).
Annual, low-growing plants; flowers yellow.
Pods kidney-shaped, without spines, Medicago lupulina (hop clover).
Pods cylindrical, with spines.

Stems pubescent; pods 3)% to 5 millimeters diameter; purple spot in
center of each leaflet; two to eight seeds in each pod, Medicago arabica
(spotted bur clover).

Stems glabrous, pods 7 to 10 millimeters diameter; no purple spot in
center of each leaflet; three to five seeds in each pod, Medicago
hispida (toothed bur clover).

MEDICAGO SATIVA (Alfalfa, Lucerne)

Roots.—Alfalfa is a deep feeder. The young plant usually
sends down a single tap root. Asarule, 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 g 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

LEGUMINOSZ 443

the variety. The average life is from five to seven years.
Fields 20 to 25 years old are found in the semi-arid sections.
At or near the ground level, is a short, compact stem (crown)
from which the numerous (20 to 50) branches arise (Fig. 186).
Blinn has shown that there is a well-defined relationship be-
tween the nature of the crown and hardiness. Non-hardy
types of alfalfa have an upright-growing crown with but few
buds and shoots developed below the soil surface. The crown
of hardy types is more spreading and the numerous buds and
shoots come from below the soil surface. Hence in the latter
case, the buds and young shoots are protected by the soil
from winter freezing. These hardy types are Grimm and
Baltic strains. The stems of alfalfa are rather slender and
freely branching. Common alfalfa has no _ rootstocks.
Some forms of Medicago falcata possess them, however, and
they also occasionally appear in some variegated types.
“Cuttings” of Alfalfa—The number of ‘‘cuttings”’ of
alfalfa depends upon the length of the growing season, and
the water supply. Three cuttings are usually made through-
out most of the alfalfa-growing regions of the United States.
In the Imperial Valley, California, ordinary alfalfa has
yielded as many as nine cuttings in a year. This practice
indicates that alfalfa has the capacity of sending up numerous
shoots from the crown. The shoots of a second or third
crop begin to appear about the time the plant is coming into
bloom, and it is the usual practice to cut the crop at this
time, so that the food supply that would normally go into
developing fruit and seed, is diverted to the young growing
shoots of the succeeding crop. Furthermore, the leaves are
richest in nutritive substances when the plant is in bloom.
The leaves contain about 80 per cent. of the protein in the
plant, hence methods of harvesting should look toward the
prevention of their loss. The different cuttings of alfalfa

444 BOTANY OF CROP PLANTS

vary somewhat in quality and chemical composition. How-
ever, more data are needed to determine the relative feeding
value of the different cuttings.

The alfalfa plant is a heavy feeder. According to Ames
and Boltz, a 3-ton yield of alfalfa hay contains 163 pounds of
nitrogen, 17 pounds of phosphorus, 99 pounds of potassium,
and go pounds of calcium.

Leaves.—The alternately arranged leaves are trifoliate
(Fig. 183,E). They are oblong in general outline and sharply
toothed along the margin; the tip is terminated by a pro-
jecting midrib. The stipules are prominent.

Inflorescense.—This is a dense raceme springing from the
axils of the branches.

Flowers.—The ordinary color of the flower is purple or
violet, but in variegated types, may be blue, green, or yellow.
The calyx teeth are longer than the tube of the calyx. The
standard is somewhat longer than the wings, which in turn
surpass the keel. The staminal tube is held in a state of
tension by two opposite lateral projections on the inside of
the keel (Fig. 188).

Pollination (Fig. 188).—Alfalfa possesses a mechanism for
the explosive dispersal of its pollen. When the edges of the
keel are spread apart, the staminal tube is released, and both
the pistil and stamens snap up against the standard. The
pollen is scattered in this process. The process is called
“tripping.” Alfalfa flowers are usually tripped by visiting
insects, chiefly bumblebees and leaf-cutting bees (Mega-
chile). The weight of an insect may be sufficient to cause
a separation of the keel edges, and consequently “tripping.”’
Usually, however, the separation is brought about by the
protrusion of the insect’s proboscis between the edges of
the keel. It has been observed that alfalfa flowers may be
tripped without the visitation of insects. This is termed

LEGUMINOS& 445

és ee wires ae
automatic” tripping. Humidity and temperature condi-
tions are probable causative factors in automatic tripping.

Both self- and cross-pollination are effective in alfalfa.

tripped

staminal tube——
free stamen ——
a

Fic. 188.—Pollination of alfalfa. A, flower untri i

3 . ’ pped with
standard removed; B, same tripped; CG, position of staminal tube eke aa
and tripped. (After U. S. Dept. Agri.) ARPS

Self-pollination usually results from automatic tripping
It is known that good seed crops are produced in regions
where tripping insects are scarce. However, the number

446 BOTANY OF CROP PLANTS

of pods set and the number of seeds per pod are increased
if cross-pollination (xenogamy) is accomplished.

Factors Affecting Seed Production—As has been indi-
cated, cross-pollination results in a greater crop of seed than
self-pollination. An abundance of tripping insects may
increase considerably the seed output; however, good seed-
crops occur in regions where tripping insects are scarce.
Seed production is usually light in humid sections of the
country. Moreover, too much irrigation water applied
during the flowering period is detrimental to seed production.
The heaviest yields of alfalfa seed occur in the arid sections
of Kansas, Colorado, Utah and Idaho. Isolated plants
invariably produce a greater crop of seed than those in a
thick stand. The sun’s heat favors automatic tripping.

Martin finds that the setting of seed pods in alfalfa is
largely dependent upon the proper functioning of the pollen.
The pollen grains require a certain amount of water to germi-
nate. When a pollen grain comes to the stigma, the 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 4 inch long. The seeds
retain their viability for many years.

Germination and Seedling.—The young seedling consists
of two short cotyledons, a hypocotyl, and a tap root. The
first foliage leaf is simple, while the second, third, and all
others are trifoliate. There is soon formed an erect stem
with but few branches; hence the first growth looks thin.
However, there spring up later numerous branches from

LEGUMINOSZ 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 sativa 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. sativa) and yellow-flowered alfalfa (M.
falcata) grow together. These hybrid forms are, of course,
unstable. They have been recrossed several times with
ordinary alfalfa and also among themselves. Such forms
have been termed ‘‘variegated alfalfas.”” Sand lucerne
(Medicago media) is considered by some botanists to be a
natural hybrid between M. sativa and M. falcata; others
consider it to be a distinct species. Sand lucerne has flowers
ranging from bluish and purple to yellow, with numerous
intermediate shades. The seeds are not as heavy as those
of common alfalfa. The plant is a hardy type. Grimm
alfalfa, as has been indicated, is quite certainly a form with
hybrid characteristics, the parents being common alfalfa and
yellow-flowered alfalfa. Other well-known types of alfalfa
are: Turkestan, German, American, Arabian, and Peruvian.

Turkestan was secured from Russian Turkestan in 1808.
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. polia). It is taller,
less branched, and more rapid in its growth and recovery
after planting than common cultivated alfalfas. Further-
more the flowers are slightly longer, and the floral bract is
longer than either calyx teeth or calyx tube.

Environmental Relations.—Alfalfa is able to withstand
high temperatures if the air is dry, but high temperatures
accompanied by a humid air are decidedly injurious. For
this reason, it is particulary well adapted to the semi-arid
sections of the United States, where it is grown both on irri-
gated and non-irrigated land. Its resistance to low temper-
atures is a varietal characteristic, and also somewhat
dependent upon cultural operations. Grimm and Baltic
types are less liable to suffer from winter killing than. the
so-called common alfalfas.

The following data shows the water requirement of alfalfas,
in comparison with other crops (from Briggs and Shantz).

Crop jsonitemant
Millets ieies-cc) serie wmans ecco lad wean eeeana ates 310
Sorghumsins en 2c. ede e.cle Seer sdeveees 538 322
COrmns ise Sanaa pent ana Geena eee 368
WAS erin ig. Beales on tinge eh ea. ch Aaa angi 513
OES sot 8k do he phone dk asain he testy ies ao 507
POtatoes= sonersrini geese erate’: pests hae ee 636
Alfalfa, Peruvian S. P. I., (30,203)............. 651

{ Alfalfa, Grimm S. P. I. (25,695)............-.. 963

LEGUMINOSE 449

In spite of its relatively high water requirement, alfalfa
is able to withstand drought. This is due to its deep root
system which draws upon the water in the lower strata of soil.

Alfalfa cannot withstand alkali, and suffers if soil drainage
is not good. - The plant requires lime in the soil. The soil
type has considerable influence upon the form of the root
system. A hard compact soil causes a more or less branch-
ing root system, while in a loose soil the tap root system is
typically developed.

Uses and Production.—Alfalfa is the most important hay
crop in the Western States. The total number of acres in
alfalfa in the United States, 1909, was 4,707,146; of this
number, the Western States furnished 4,523,513 acres.
The five leading States, 1909, named in the order of their
alfalfa production were Kansas, Nebraska, Colorado, Cal.
fornia and Idaho.

MEDICAGO LUPULINA (Hop Clover, Black Medic, Yellow 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 obovate, oval or orbicular, denticulate or
crenulate leaflets. The flowers are small, yellow, in dense,
oblong or cylindrical heads. The pods are black, curved,
strongly veined, and one-seeded.

The plant is a native of Eurasia. It is now found through-
out the greater part of the United States and other temperate
regions where it occurs in fields and waste places. It is
sometimes planted on poor soil, and has some promise as
a green manure.

MEDICAGO ARABICA (Spotted Bur Clover)

This is a smooth annual plant with procumbent stems.
The leaflets have a dark purple spot in the center. The pods
29

450 BOTANY OF CROP PLANTS

e

G@ €

Fic. 189.—Pods of 10 species of Medicago. Top row, M. arabica and M.
hispida denticulata; second row, M. hispida confinis and M. hispida tere-
bellum; third row, M. muricata and M. hispida nigra; fourth row, M. ciliaris
and M. echinus; bottom row, M. scutellata and M.orbicularis. (After McKee
and Ricker, U. S. Dept. of Agr.)

LEGUMINOS 451

(Fig. 189) are in long clusters, twisted into three to five
spirals, and the edges bear numerous grooved spines which
interlock. The seeds are kidney-shaped, and about 214 milli-
meters long. Medicago arabica inermis is a spineless-podded
form..

Fic. 190.—Toothed bur clover (Medicago hispida).

Spotted bur clover is a native of Europe and Western
Asia. It is introduced into the United States and occurs on
the Atlantic, Gulf, and California coasts. It is being used
as a pasturage crop.

452 BOTANY OF CROP PLANTS
MEDICAGO HISPIDA (Toothed Bur Clover)

Toothed bur ‘clover (Fig. 190) is a smooth, annual plant
with decumbent leaves. The /eaflets often have small whitish
and dark red spots scattered over the surface, which disap-
pear with age. The flowers are yellow. The pods are netted-
veined, twisted spirally, and spiny. The seeds are light- to
brownish-yellow, kidney-shaped, and about 3 millimeters
long. Medicago hispida reticulata and M. hispida confinis
are forms with spineless pods. Toothed bur clover, Medi-
cago hispida denticulata, is native to the northern Mediter-
ranean region. It is the most common bur clover grown in
California. It finds some use as a pasture, hay, cover and
green-manure crop.

In addition to the two species of bur clover given above,
there are about 35 species that are not cultivated to any
extent. They are all native to the Mediterranean region.
All are warm-climate crops.

MELILOTUS (Sweet Clover)

Generic Description.—Sweet clovers are tall, erect, annual
or biennial herbs, with a fragrant odor, especially when
bruised. The leaves (Fig. 183, B) are pinnately three-foliate,
petioled, and possess large stipules and dentate leaflets, the
veins of which end in the teeth. The flowers are long, slender,
and in one-sided, axillary racemes. They are small, and
white or yellow. The calyx teeth are short and about equal.
The standard is obovate or oblong, the wings oblong, and
the keel short and obtuse. The stamens are diadelphous
(nine and one). The sessile or stalked ovary bears a single
thread-like style. The pods are ovoid or globose, small,
indehiscent or finally 2-valved, and usually one-seeded.
Ordinarily, all the seeds of one year’s production do not

LEGUMINOSA 453

germinate the first season. This results from the production
of some “‘hard seeds.”

There are 15 to 20 species of sweet clover, natives of
Europe, Africa, and Asia. They are known by different
names, such as wild alfalfa, melilot, giant clover, Bokhara,
and sweet clover.

Fic. 191.—Leaves and inflorescence of white sweet clover (Melilotus alba) on
left, and alfalfa (Medicago sativa) on right.

The young plants resemble alfalfa, from which they can
be distinguished by the bitter taste of the foliage and the
thicker leaflets.

Species of Melilotus.—There are two common species of
Melilotus: M. alba, white sweet clover, and M. officinalis,

454 BOTANY OF CROP PLANTS

yellow sweet clover. Several other species of Melilotus
have been used agriculturally to some extent; among such
are M. indica (“sour clover’), M. altissima, M. gracilis,
and M. speciosa.

The characters of the two most important species are
arranged in parallel rows for purposes of comparison.

i M. alba M. officinalis
Commonly biennial. Commonly annual, sometimes bien-
Flowers white. nial.
Standard slightly longer than wings. _ Flowers yellow.
Pods ovoid, glabrous. Standard about equal the wings.

Pods ovoid, often slightly pubescent.

MELILOTUS ALBA (White Sweet Clover)

Description.—This is an erect and smooth-stemed bien-
nial. It may reach a height of 3 or 4 feet the first season,
from seed; the second season’s growth is much more vigorous,
and will‘ yield two crops in the Northern, and three in the-
Southern States. New sprouts arise from above ground
near the base of the plant after each cutting, and for this
reason the plants must not be cut too close to the ground
line. The leaves have thick, oblong, finely toothed leaflets
which are narrowed at the base, and truncate, notched or
rounded at the apex. The racemes are numerous, slender,
and often one-sided. The flowers are white and have a
standard which is somewhat longer than the wings. The
pods are ovoid, slightly reticulated (netted), and smooth.

The species is a native of Eurasia. It is a common road-
side and waste-place weed throughout this country.

MELILOTUS OFFICINALIS (Yellow Sweet Clover)

Desctiption.—This plant is much like the preceding. It
does not grow so tall, however, is less common, and has

LEGUMINOSZ 455

yellow flowers. It blooms somewhat earlier than the white
sweet clover and is more commonly annual in its habit than
biennial. It is a native of Eurasia and, like the preceding
species, has become naturalized in this country, being widely
distributed as a ruderal throughout both the Northern and
Southern States.

Environmental Relations——The sweet clovers thrive in
both semi-arid and humid climates, and upon all types of
soils—heavy and light, rich and poor, well-drained and illy-
drained. They are also drought-resistant. It is being intro-
duced where, for any reason, alfalfa and clover have failed.

Uses of Sweet Clovers.—Like other legumes, sweet clover
supports nodules of bacteria on its roots. In fact, it is
nearly as valuable as alfalfa to plow under as a green manure
to renew the soil. It makes good hay when properly
handled, and for pasturage purposes it has considerable
value. As a forage crop, it can be utilized where alfalfa
or red clover cannot be grown successfully. The plant
becomes coarse and unpalatable soon after blooming, and
hence it must be cut before this stage. The plants possess
a bitter principle, cumarin, which may cause an animal to
reject them as food at first, but usually the animal becomes
accustomed to them.

White sweet clover is much larger and more vigorous than
yellow, and consequently is the one recommended for
cultivation.

SOJA (Soy Bean)

Generic Description.—The soy beans are prostrate or
erect herbs with pinnately three-, rarely five- or seven-, foliate
leaves. The flowers are in short axillary racemes, and are
purple or whitish. The pods are linear or falcate, and two-
valved. The seeds are globular and pea-like.

456 BOTANY OF CROP PLANTS

There are between 15 and 20 species of Soja, natives of
tropical Asia, Africa, and Australia. There is only one
species of any economic importance. This is Soja max.

SOJA MAX (Soy Bean, Soja Bean, Coffee Bean)

Description—This is an erect, bushy appearing, hairy
annual, varying from 14 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
a white or purple in color.

Fic. 192—Soy bean (Soja max). The flowers are self-pollinated

a as a rule, and are completely
self-fertile. Occasional cross-fertilization occurs in the field
when varieties are planted very close together. The pods
are from 1 to 2}4 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

LEGUMINOSE 457

climates. The seeds vary greatly in color; there are shades
of cream, white, yellow, green, brown, and black; they also
vary in shape from globose to elliptical. Under the most
favorable conditions, soy bean seeds do not retain their
viability for more than five or six years.

Soja max is a native of China and Japan. The cultivated
varieties are adapted to the warmer sections of the United
States; they are intolerant of cool nights. However, there
are several very early maturing varieties which may be grown
in the northern tier of States. The soy bean will grow in
moist climates, and also manifests drought-resistant pro-
pensities. The plant is grown on a variety of soil types, and
will even produce a fair crop on poor soils of a sandy nature.

Uses.—The soy bean is the most important legume in
Asiatic countries, and is becoming of increasing value in the
United States. The chief product of the bean is the oil
which is expressed from the seeds. It is used in the manu-
facture of soaps, lubricants, water-proof goods, linoleum,
rubber substitutes and printing ink; also in the preparation
of varnishes and paints, as a substitute for linseed oil. After
the oil is expressed from the seed, the ‘‘cake,” either un-
ground or ground into a meal, is used as stock -feed or as a
fertilizer. Soy-bean meal is of considerable value as human
food. Soy-bean flour is an important constituent in many
food specialties such as diabetic breads, crackers and bis-
cuits. Soy-bean flour is very low in carbohydrates, that
made from soy-bean cake having a carbohydrate content
of 33.85 per cent.," as compared with 75.35 per cent. in
wheat flour. The protein content of flour made from soy-
bean cake is given as 47.3 per cent., whereas that of wheat
flour is but 11 per cent. Soy beans are also utilized to
make a so-called soy-bean milk, which is valued for cooking

1 Data from the U. S. Dept. of Agri. Bureau of Chemistry.

458 BOTANY OF CROP PLANTS

purposes by bakers, confectioners and chocolate manufac-
turers. The seeds of soy beans are sometimes used as a
substitute for coffee. Soy-bean hay has a comparatively
high feeding value. It is recommended as a pasture for
hogs. The plant is recognized as a valuable soiling and
ensilage crop. Nitrogen-fixing bacterial nodules occur on
the roots of the soy bean.

VIGNA (Cowpea and Related Species)

Description—The ‘‘Vignas” are usually climbing or
trailing herbs, sometimes erect, that are much like the com-
mon bean. They differ from the common bean (Phaseolus
vulgaris), however, mainly in that the keel of the corolla is
short and merely incurved rather than spirally coiled. The
leaves are'pinnately trifoliate. The flowers are yellowish or
purplish, in head-shaped or racemose inflorescences at the
ends of long peduncles; these arise in the axils of leaves.
The calyx is five-toothed. The stamens 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 1 to 3 feet long, and kidney-

Fic. 193.—Seeds of 16 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 arc
cowpeas (Vigna sinensis). (After Piper, U. S. Dept. of Agri.)

459

LEGUMINOS

cote Or esr P@es ove
cour’é © OC EL OES
coerc€ Greer) e
(O11 (461 SA
retie ee Or ECB 68

couree Or €C KET 6 we)

460 BOTANY OF CROP PLANTS

shaped seeds 8 to 12 millimeters long. In catjang, the pods
are small, 3 to 5 inches long, and usually erect or ascending
(Fig. 194). In the cowpea, the pods are 8 to 12 inches long,
and become pendant with age. The cowpea is by far the
most important, economically.

Fic. 194.—A, flowers and fruit of catjang (Vigna catjang); B, flowers and
fruit of cowpea (Vigna sinensis). (After U. S. Dept. of Agri.)

VIGNA SINENSIS (Cowpea)

Description.—The cowpea is a vigorous annual herb with
a strong tap root which sends out large side roots almost
horizontally for 1 or 2 feet (Fig. 195). The greater part of the
root system lies in the first 114 feet of soil. The varieties vary
in habit from prostrate trailing herbs to tall and half-bushy
forms. The cowpea has an indeterminate growth, that is,
it continues to grow indefinitely, providing environmental
conditions are favorable. As in the majority of plants
vegetative growth is favored by an abundance of water and

LEGUMINOSE 461

heat, and seed production is stimulated by adverse condi-
tions. The first pods may come to maturity within seventy
to ninety days in the so-called early varieties; on the other
hand, some varieties do not even come into bloom under
conditions prevailing in the states along the Gulf of Mexico.

The flowers are white or
pale violet with three
bracts at the base of each
pedicel. The cowpea
flower is capable of self-
fertilization, and this is
probably the most com-
mon occurrence although
the flowers are often visited
by honey bees or bumble-
bees. They are attracted
chiefly by the extra-floral
nectaries. The long pods
(Fig. 194) are cylindrical,
somewhat curved, and
usually constricted _ be-
tween the seeds. The
seeds are numerous, usu-
ally bean-shaped, spotted,
marbled, speckled, or mar-
bled and speckled, and
have a dark circle around
the white hilum. Great

Fic. 195.—-Cowpea (Vigna sinensis).
(After Piper.)

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.

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 localities as a catch crop or as a green
manure, and is adapted to rotation in a cropping system.
The seeds are fed to poultry, and are also recommended as
a food for man. The roasted seeds are a substitute for
coffee.

ARACHIS HYPOGGA (Peanut, Goober)

Habit, Stem.—The peanut is an annual plant with a tap
root (Fig. 196). The plant may be low and prostrate, as in
the “‘running types,” or upright and bushy, as in the ‘bush
types.” The stems are thick, angular, branching, and hairy.

Leaves.—The leaves are pinnately compound, usually
with two pairs of subsessile, entire leaflets, and no tendrils;
the elongated stipules are adnate to the petiole base.

Flowers (Fig. 197)——The flowers are axillary, sessile,
and orange-yellow in color. There are two sorts of flowers
on the plant, sterile and fertile. Sterile flowers are most
numerous in the upper axils, on long, slender pedicels; they
have monadelphous stamens (nine united, one abortive)
and a minute abortive ovary. The calyx tube is long and
slender, and bears on its rim the calyx lobes, corolla, and

LEGUMINOSZ 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.

Fic. 196.—Peanut_ (Arachis hypogea). (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

Types.—The American varieties may be divided into two
large groups: (1) 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
Bi sana ao Hetaee 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. il, salted peanuts and peanut candies

\ *\stamunal tube
‘calyx lobe

LEGUMINOS ‘465

are other products. The nuts (“‘goobers’’) are fed to hogs,
or the animals are turned in to pasture on both the vines
and nuts. Peanut oil, pressed from the seeds, is a nearly
colorless product, which is employed as a salad oil, to a
limited extent in the manufacture of soap, and in the making
of oleomargarines and similar compounds. Analyses show
that Spanish and Valencia peanuts are richer in oil than
Virginia and other common types. The percentage of oil
in shelled nuts varies from about 45 to 50 per cent. Peanut
meal, the product left after pressing the oil from the seeds,
is a high-grade stock feed. Nearly all peanut oil used in
this country is madein Europe. The United States imported
1,332,108 gallons of the oil during 1914.

LESS IMPORTANT LEGUMES

The following list includes several of the less important
members, agriculturally, of the Pea Family.

Lupinus (Lupines).—Annual or perennial herbs with palmately seven- to
fifteen- foliate leaves, and spikes of white, yellow, or blue, showy flowers.
They can grow on poor sandy soil, but are little used in this country except
to plow under as a green manure. The species used for this purpose are
annuals.

Lespedeza striata (Japan Clover).—A branched, spreading annual with
three-foliate leaves, short petioles, and small flowers in the axils of the leaves.
It was introduced from Japan or China to the South Atlantic States, where
it is quite largely grown for pasture and hay. It is adapted to clay soils and
does well on thin uplands.

Onobrychis vicieefolia (Sainfoin)—A deep-rooted perennial with erect
stems, odd-pinnate leaves, six to twelve leaflets, and erect, dense racemes of
rose-colored flowers. The one-seeded, brown, lens-shaped pods are indehis-
cent. The seed loses its viability rapidly, and'is slow to germinate.

The plant was early introduced into America from Asia, but it is little
grown here. It is adapted to dry barren lands that are not suited to clovers
and alfalfas. It has been grown with success on calcareous soils.

Ornithopus sativus (Serradella).—A low, branched annual, with pinnately
compound leaves, and rose-colored or purplish flowers in umbels. The pods

3°

466 BOTANY OF CROP PLANTS

break into joints. The plant makes good hay and thrives on fairly thin soils,
if not dry. It grows best in cool weather, and is not very hardy.

Lotus corniculatus (Birds-foot Trefoil)—An annual plant similar to
clover. The low-spreading stems are from a long tap root; bright yellow or

Fic. 198.—Chick pea (Cicer arietinum).

red flowers occur in small clusters at the ends of the stems; pods are narrow
and pendant. It is an Old World plant, but is naturalized in the South
where it is sown in mixtures for dry pastures.

LEGUMINOSZ 467

Cicer arietinum (Chick-pea).—A bushy, hairy annual, 1 to 2 feet high,
with odd-pinnate leaves and small, white or pink, solitary flowers, followed
by short, thin pods. The seeds are pea-like, with a beak-like projection near
the hilum. The plant is grown in Europe, Asia, and‘ Mexico for its seeds
which are used for both stock and human food. The herbage is unfit for
stock because of a poisonous principle. The seeds have been used as a coffee
substitute.

Trigonella foenum-greecum (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 Viciee and Phaseolee of Ohio.
Ohio Nat., 15: 393-404, 1914.

Beat, A. C.: Evolution and Pollination of the Sweet Pea. Florist’s Exch.,
32: 140-141, IQII.

BeaTTi£, 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, Puizo.: Alfalfa—the Relation of Type to Hardiness. Colo. Agr. Exp.
Sta. Bul). 181: 1-16, rg1t.

Frencu, G. T.. Observations on Medicago lupulina L. Science, n. s., 2,
28: 127, 1908.

Foucsxo, Mimaty: Uber die biologischen und entwickelungsgeschichtlichen
Verhaltnisse des Pericarps der Papilionaten. Ung. Bot. BI., 8: 264-265,
1909.

Anatomie, Entwickelung und Biologie der Fruchtwand der Papilionate.
Bot. Kézlem, 8: 154-212, 1909.

Grecory, R. P.: The Seed Characters of Pisum sativum. New Phytol., 2:
226-228, 1903.

Hanpy, R. B.: Peanuts: Culture and Uses. U.S. Dept. Agr. Farmers’ Bull.
25: 1-23, 1896.

HEApDDEN, Ws. P.: Alfalfa. Colo. Agr. Exp. Sta. Bull. 35: 1-92, 1896.

Jones, B. W.: The Peanut Plant. Orange Judd Co., 1885.

Krrcuner, 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, Rowanp, 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.

OaxLey, R. A., and GARVER, SAMUEL: Medico falcata, a Yellow-flowered
Alfafa. U.S., Dept. Agr. Bull. 428: 1-70, 1917.

468 BOTANY OE CROP PLANTS

PAMMEL, Epna C., and Crark, CLarissa: Studies in Variation of Red Clover.
Proc. Ia. Acad. Sci., 18: 47-53, 1911-

PaMMEL,'L. H., and Krnc, Cuartorre M.: Pollination of Clover. Proc. Ia.
Acad. Sci., 18: 35-45, 1911.

Pollination of Clover. Contrib. Bot. Dept. Ia. State College, 47: 1-45, 1911.

PFENNINGER, Urs.: Untersuchung der Fruchte von Phaseolus vulgaris L. in
verschiedenen Entwickelungstadien. Ber. Deut. Bot. Ges., 27: 227-234,
1909.

Prrer, C. V., and Morse, W. J.: The Soybean; History, Varieties, and Field
Studies. U.S. Dept. Agr. Bur. Plant Ind. Bull. 197: 1-84, 1910.

Five Oriental Species of Beans. U.S. Dept. Agr. Bull. 119: 1-32, 1914.

The Bonavist, Lablab, or Hyacinth Bean. U.S. Dept. Agr. Bull. 318:
I-15, 1915.

The Soy Bean, with Special Reference to Its Utilization for Oil, Cake and
Other Products. U.S. Dept. Agr. Bull. 439: 1-20, 1916.

Piper, C. V.: Agricultural Varieties of the Cowpea and Immediately Related
Species. U.S. Dept. Agr. Bur. Plant Ind. Bull. 229: 1-160, 1912.

Soja Max. Jour. Am. Soc. Agron., 6: 75-84, 1914.

Piper, C. V., Evans, Morcan W., McKee, Rotanp, and Morsz, W. J.:
Alfalfa Seed Production; Pollination Studies. U.S. Dept. Agr. Bull. 75:
I-32, IQT4.

Prrer, C. V., and McKee, Roxanp: Vetches. U.S. Dept. Agr. Farmers’
Bull. 515: 1-28, 1912.

ScoFIELD, Cart S.: The Botanical History and Classification of Alfalfa
U.S. Dept. Agr. Bur. Plant Ind. Bull. 131: 11-19, 1908.

SHaw, Tuomas: 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. rog: 1-173, 1907.

WEstcatE, J. M.: Variegated Alfalfa. U.S. Dept. Agr. Bur. Plant Ind. Bull.
169: 1-63, 1910. 2 .

WestcaTE, J. M., and Hiziman, F. H.: Red Clover. U. S. Dept. Agr.
Farmers’ Bull. 455: 1-48, 1911.

WEst¢ATE, J. M., and Vinatt, H. N.: Sweet Clover. U. S. Dept. Agr.
Farmers’ Bull. 485: 7-39, 1912.

WesteatE, J. M., Cor, H. S., Wrancxo, A. T., Ropsins, F. E., Hucues, H.
D., PamMet, L. H., and Martin, J. N.: Red-clover Seed Production:
Pollination Studies. U.S. Dept. Agr. Bull. 289: 1-31, 1915.

Wicat, 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
LINACEZ (Flax Family)

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.
21) 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 staméns
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 OF CROP PLANTS

The Names Derived from “Linum.”—This family contains
but one important genus, Linum. The name Linum is the
latin for flax. The word “linen” means made from flax or
of flax. It is from these and other similar foreign names
that we get our common words linen, lint, linseed, and line.

Geographical, and Environmental Relations——The family
has about 135 species, which are widely distributed over the
world. The important commercial species is L. usitatissi-
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 1 to 4 feet
(Fig. 199).

It is a dainty surface feeder with a small root system; this
consists of a slender tap rogt 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

LINACEE 471

rigid, at the same time retaining considerable elasticity due
to the bast fibers.

Flax Fibers.—Three tissue areas are recognizable in the
stem: pith, wood, and bark. The flax bark contains the
bast or flax fiber cells. These bast fibers give flax straw

Fic. 199.—Common flax (Linum usitatissimum).

its great financial value since they make up the part from
which linen is made. Each bast fiber is a single cell, 25 to
30 millimeters long, and cylindrical in shape.

Leaves, Inflorescence and Flowers.—The leaves are
narrow, entire, and blunt at the apex. The inflorescence

472 BOTANY OF CROP PLANTS

is loosely cymose. The flowers vary in color from white to
deep blue. The same plant always bears flowers of the
same color. Yellow-flowered varieties are not found in
this species. The petals are large, conspicuous, wedge-
shaped, and about twice as long as the sepals.

Pollination.—Studies of flax varieties indicate that there
is close-pollination. Individual flowers produce seed freely,
whether associated with other flowers or not. Examination
of flax flowers at the proper time shows anthers in close
proximity to the stigmas, and the latter covered with pollen.

Mature Fruit.—The flax fruit (Fig. 21) is a round capsule
known commercially as the “seed ball.’”’ The seed ball is com-
posed of five fused carpels. The balls are divided into five
true cavities or locules by means of five true partitions (septi)
extending from the wall (pericarp) to the axis. Each locule
contains two seeds and is divided more or less incompletely
into two loculi by means of false septi. The seed balls are
14 inch or more in diameter. When fully ripe, they are
easily separated into parts at the points where the carpels
are joined.

Seeds.—The seeds vary in length from 4 to 1¢ inch.
They are lenticular, compressed, and slightly longer than
wide. They have a very smooth, polished surface and vary
in color from yellow to dark brown. Light brown is the
standard color. A mucilaginous material which quickly
becomes sticky (viscid) in hot water is found filling the
epidermal cells of the seed. It is this substance which gives
flax its medicinal value. The embryo is surrounded by a
thin layer of endosperm which, in the mature seed, contains
starch.

Geographical.—Common flax is a native of Europe. It is now widely dis-
tributed over the world, being grown commercially in many countries. India
is a heavy producer of seed, and in Argentina it is grown extensively for oil.

LINACEE 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
165°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 in this section. Flax fiber is also utilized
for making thread, carpet yarns, fishing lines, seine twines,
etc. It is also employed to some extent for upholstering,
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LINACEE 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.—F lax 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
RUTACEZ (Rue Family)

Description.—This family is represented by trees, shrubs,
and herbs. The leaves are alternate or opposite, simple or
compound, exstipulate, and glandular-dotted. The glands,
which appear as translucent dots, are internal. They vary
somewhat in size and shape. The flowers (Figs. 200 and 201)
are solitary or in small axillary or terminal cymes. The sepals
are four to five in number, but sometimes
absent. There are as many petals as
sepals, and they are either hypogynous or
perigynous. The separate or united
stamens are attached to the receptacle,
and vary considerably in number; the
anthers are two-celled, usually versatile, Fic. 200.—Floral
and introrsely dehiscent. The two to five pee
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 110 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

RUTACEE 477

Key To Important GENERA OF RUTACE#!
Leaves trifoliate, Poncirus (trifoliate orange).
Leaves unifoliate.
Ovary three- to seven-celled; ovules two in each cell; stigma cavernous,
Fortunella (kumquat).
Ovary eight- to fifteen-celled; usually more than two ovules in each cell;
stigma solid, Citrus (orange, lemon, grapefruit, lime, etc.).

Fic. 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 18 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-

1Hume 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 purplish-pink flowers are solitary,
or in small axillary or terminal cymes or panicles. The
flowers are hermaphroditic; the calyx is three- to six-toothed ;
the corolla has four to eight separate thick segments (petals) ;
and there are 20 to 60 stamens, 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-fertilization, and more-
over, will not set fruit unless pollen is derived from certain
congenial varieties. Pollination may occur without the
visitation of insects. The time for complete fertilization
after pollination varies from thirty hours in Satsuma oranges
to four weeks in trifoliate oranges. Parthenocarpic varieties
seldom bear viable pollen. In navel oranges there is no
pollen in the anthers at flowering. time.

Fruit—The fruit is a modified berry (hesperidium);
it is spherical or spheroidal and is made up of a thick,
leathery “‘rind’’ with numerous lysigenous oil glands, and a
juicy pulp composed of numerous stalked “juice sacks.”

RUTACEZ 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:
(1) 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‘ong, 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, 114 to 2}4 inches in diameter, its skin thin, C. aurantifolia
(lime).
Fruit large, its skin thick.
Tree small, 12 to 20 feet tall; skin of fruit easily removed, C. nobilis
(king orange).
Tree large, 20 to 40 feet high; skin of fruit not easily removed, C.
sinensis (common sweet orange).
Leaves broadly winged.
Fruit large, pale lemon-yellow when ripe, C. grandis (grapefruit, pomelo,
shaddock).
Fruit medium-sized, orange-colored or reddish when ripe, C. aurantium
(sour or Seville orange).

CITRUS MEDICA (Citron)

Description —This is a shrub or small tree with short,
stout thorns; the /eaves 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 g to 10 locules; the fruit is large, 6 to g 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

RUTACEE 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 ro to 20 feet in
height, with short, stout thorns; the leaves are 2 to 3 inches
long, long-ovate, sharp-pointed, serrate, and its petioles
wingless; the large flowers are axillary, usually solitary,

Fic. 203.—A citrus orchard in Southern California (From Calif. Agr. Exp.
Sta.)

sometimes in small clusters; their petals are white inside,
and purplish above; the stamens are usually between 20
and 3c in number; the ovary has 7 to 10 locules. There are
three sorts of flowers in the lemon: (1) perfect flowers, (2)
flowers with rudimentary pistils and normal stamens, and
(3) flowers that fail to develop beyond the bud stage. The
first class is the only one to set fruit. The fruit is about 3
31

482 BOTANY OF CROP PLANTS

inches long, light yellow when mature, its skin medium-
thick, the pulp abundant and acid, and the juice sacks long
and pointed. The fruit requires about nine months to
reach maturity.

Geographical.—The lemon is probably a native of India. It is cultivated
extensively in the Mediterranean region, and to a considerable extent in Cali-
fornia and Florida.

Colpr of Lemon Fruit.—Lemons are picked when they
reach a size demanded by the market, regardless of the
‘degree of maturity. Hence many of the lemons, when
picked, are dark green, and not the lemon-yellow of those
we buy in the market. The fruit is colored and ripened be-
fore shipment. If they are not to be shipped for several
months, they are placed in storage houses where coloring
and ripening goes on gradually. However, if they are to be
shipped soon after picking, the coloring process is hastened.
This is done by putting them in “sweat rooms” that are
kept at a temperature between 90° and 95°F. The proper

..color is obtained by this treatment within four to six days. -

Uses.—Lemons are used in the home for lemonade, as an.
ingredient in a number of prepared foods, as a stain-remover, ”
and as a bleaching agent. One of the chief uses of lemons
is in the manufacture of lemon extract. ©

Lemon Extract——This ranks second to vanilla extract in
the quantity consumed. Sicily now produces the world’s
supply of lemon oil. Cull lemons are utilized for the pro-
duction of the oil. Lemon extract is made by dissolving 5
parts of lemon oil in g5 parts of strong alcohol. Lemon oil
is secreted by special cells in the outer surface of the rind.
About g5 per cent. of the lemon oil produced is obtained from
the lemons by the sponge method, the remainder by the
machine method. There are two sponge methods, known as
the two-piece, and three-piece sponge methods. In the former

RUTACE 483

method the lemons are cut by hand into two pieces, and the
pulp removed; the rinds are then thoroughly soaked in water,
and after standing for several hours, passed on to the spongers.
The apparatus of the sponger consists of a round stick about
t 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 1 pound of
oil is secured from 1,600 to 2,200 lemon halves. The three-
piece method differs but slightly from the preceding.

CITRUS AURANTIFOLIA (Lime)

Description.— This is a small straggling tree or shrub, with
numerous, small, very sharp thorns; the small leaves are
elliptic-oval, 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 fruzt is small,
from 114 to 214 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 “limequat” is a hybrid between a
kumquat and the Mexican lime.

484 BOTANY OF CROP PLANTS

CITRUS SINENSIS (Common or Sweet Orange)

Description.—The sweet orange tree is 25 to 40 feet high,
round-topped, and usually bears slender, flexible, blunt
spines; the leaves are oval or ovate-oblong, and the petioles
are narrowly winged, articulated both with the blade and
the twig; the flowers occur singly or in small cluster; the petals
are white above and below; there are from 20 to 25 stamens;
the ovary has 10 to 14 locules; the fruit is subglobular, light
orange to reddish, smooth, the pulp abundant and sweet, and
the juice sacks spindle-shaped.

Geographical— The sweet orange is the most widely cultivated of all
citrus fruits; it is probably a native of southeastern Asia.

Types.—There are a number of groups or types of sweet
oranges; the four principal ones are Spanish oranges, Med-
iterranean oranges, blood oranges, and navel oranges. Spanish
oranges have large, coarse-grained fruit. Mediterranean
oranges are of good quality and fine-grained. Blood oranges
have red pulp or white pulp streaked with red; the fruit
is of good quality. Navel oranges are so named on account
of the umbilical mark at the apex of the fruit. This mark is
due to the protrusion of additional carpels developed within
the fruit.

Uses.— Whereas oranges were once regarded as luxuries,
they are now produced in such quantities and sold at such
prices as to be within the reach of the majority of people.
Oranges are used mainly as a fresh dessert. Orange extract
is made by dissolving orange oil in strong alcohol. Up to the
year 1911, almost the entire world’s supply of orange oil
came from Sicily, Italy and adjacent parts of southern
Europe. Since then the West Indies have developed the
industry.

The oil is used in the manufacture of perfumes, soaps, and
flavoring extracts, and to a slight extent as a drug.

RUTACE 485

Hood and Russell have recently pointed out that the ex-
traction of sweet orange oil is a commercial possibility in
this country, and that waste oranges may be utilized.

CITRUS NOBILIS (King Orange)

Description—The King orange tree is 12 to 20 feet tall,
with slender, drooping branches, and thornless, or with small
sharp spines; the Jeaves are small, lanceolate to oval, and the
petioles are wingless or very narrowly winged; the flowers
occur singly or in small clusters; the petals are white above
and below, fleshy and recurved; there are from 18 to 24
stamens; the ovary has g to 15 locules; the /rwit is oblate,
orange to reddish in color, its peel loose and easily removed,
the pulp sweet or sub-acid, and the juice sacks broad and
blunt.

Varieties.—Citrus nobilis var. deliciosa is the mandarin
orange. In this variety are included the tangerine varieties,
which have an easily removable skin and segments that come
apart readily, also the tangelo which is a hybrid between the
tangerine and the Bowen grapefruit. Citrus nobilis var.
unshiu is the Satsuma or Unshiu orange. It is a small,
spineless, dwarf tree, and very hardy.

CITRUS GRANDIS (Grapefruit, Pomelo, Shaddock)

Description.— This species is a large tree, 20 to 40 feet in
height, with slender, flexible spines, if present; the leaves
are large, ovate, crenate, broadly rounded at the base, and
the petioles are broadly winged and ‘articulated; the flowers
are borne singly or in clusters of 2 to 20; the petals are white
both above and below; there are from 20 to 25 stamens, with
large linear anthers; the ovary has from 11 to 14 locules; the
fruit is very large, 4 to 6 inches in diameter, globose, oblate
or pear-shaped, pale lemon-yellow when ripe, its skin smooth,

486 BOTANY OF CROP PLANTS

the pulp peculiarly acid or sub-acid, and the juice sacks large
and spindle-shaped.

Fic. 204.—Pomelo (Citrus grandis), in the fourth summer. (From Calif.
Agr. Exp. Sta.)

Geographical.—The species is a native of Polynesia and the Malay Archi-
pelago. It is now grown in the United States.

RUTACEE 487

Variety and Name.—The name grapefruit is the one that
this species is known by commercially. Shaddock is a horti-
cultural variety, the fruit of which is much larger than the
common grapefruit. It is a coarse, thick-skinned fruit, with
thick, leathery septa between the locules, and is of no com-
mercial importance. The name pomelo is now recognized by
most horticulturists. Grapefruit is a well-known breakfast
fruit.

CITRUS AURANTIUM (Sour or Seville Orange)

Description.—The sour orange tree is 20 to 30 feet high,
and bears long, flexible, blunt spines; the /eaves are 3 to 4
inches long, wedge-shaped at the base, pointed at the tip,
and the petioles are broadly winged; the flowers are borne
singly or in small axillary cymes; the fragrant glandular-
dotted petals are white above and below; there are from 20
to 24 stamens; the ovary has 6 to 14 locules; the fruit is
globose, orange-colored or reddish, rough, the pulp acid, and
the juice sacks small and spindle-shaped.

Geographical.—The sour orange is probably a native of southeastern Asia.

It is cultivated in the United States, being used as a stock on which to bud
other citrus fruits.

Other Species of Citrus.—Other Citrus species of less
commercial importance in the United States are C. mitis,

‘the Calamondin orange, C. ichangensis, Ichang lemon, and
C. bergamia, bergamot.

FORTUNELLA (Citrus) (Kumquat or Kinkan)

Description.—The kumquats are evergreen shrubs with
simple, glandular Jeaves; 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 thrée to seven cells,

4nd BOTANY OF CROV PLANTS

and cach cell contains two ovules; a characteristic feature of
the flower is the cavernous stigma; the fruit is small, 1 to
t£{ inches in diameter, its rind usually thick, fleshy, spicy,

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and aromatic, its juice acid, and its seeds small and pointed;
there may be one or two crops of bloom and fruit in a growing
season.

Species.- The two most common species of Forlunella
are I’ margarila, the Oval or Nagami kumquat, and 2.

RUTACEE 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.

PONCIRUS, (Trifoliate Orange)

Description.—The trifoliate orange is a low tree, seldom
over 15 feet high; the older branches are thorny, the thorns
being 1 to 14 inches long, and flattened at the base; the
characteristic deciduous trifoliate leaves are composed of
thin, elliptical, crenate or dentate leaflets; the flowers usually
appear before the leaves, singly or in pairs in the leaf axils;
the five sepals are greenish yellow in color, and pointed at
the tip; the corolla is white; the fruzt 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.

Corr, J. E.: A Study of the Factors Influencing Seed Formation in Citrus
Fruits. Calif. Agr. Exp. Sta. Rpt., ro5—106, 1914.

Citrus Fruits. The MacMillan Co., 1915.

Hoop, S. C., and Russett, G. A.: The Production of Sweet-orange Oil and
a New Machine for Peeling Citrus Fruits. U.S. Dept. Agr. Bull. 399:
I-19, 1916.

Hume, H. Harorp: 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.

Ikepa, Tomocarxa: 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. s

SrRasBuRGER, E.: Uber Polyembryonie. Jenaisch. Zeitsch. Naturwiss.,
12: 647-670, 1878. ;

WesBER, H. J.: Complications in Citrus Hybridization Caused by Poly-
embryony. Science, n. s., 11: 308, 1900.

CHAPTER XXXII

VITACEZ: (Grape Family)

Family Description—Members of the grape family are

either climbers or erect shrubs with nodose joints.
an abundance of watery sap.

petioled, either simple (Vitis)
or compound (Parthenocissus)
(Fig. 206). The inflores-
cence is commonly a panicle
(Vitis) or a cyme (Partheno-
cissus). The flowers (Fig.
210) are small, greenish,
perfect or polygamo-dicecious
(perfect flowers on one indi-
vidual and imperfect on
another). The calyx is en-
tire or four- to five-toothed.
The four to five petals are
either separate or united and
fall away very soon after
development. Stamens are
four to five in number and
opposite the petals. The

There is
The leaves are alternate and’

Fic. 206.—Compound digitate leaf
of Virginia creeper (Parthenocissus
quinquefolia).

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 ro genera and 450 species in this family,
many of which are natives to tropical countries.

491

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 Ivy).

These may

be distinguished as follows (as far as our species are concerned):

Fic. 207.—Two

types of grape
stems cut in me-
dian lengthwise
section. A,south-
ern fox grape
(Vitis rotundifo-
lia) with pith con-
tinuous at the
nodes; B, old
world grape (V.
vinifera) with pith
interrupted at the
nodes. (After
Hedrick.)

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
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

VITACEE 493

‘

shown by the fact that they sometimes bear small leaves or
flowers. In the Fox grape (Fig. 208), there is either a tendril
or an inflorescence opposite each leaf. This continuity

Fic. 208.—Northern fox grape (Vitis labrusca).

is somewhat variable, however. In all other species, there
are two successive leaves with a tendril or inflorescence oppo-

404 BOTANY OF CROP PLANTS

Fic. 209.—Fruit-bearing shoot of river-bank grape (Vitis riparia). (After
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 labrusca averages
three to six clusters to a cane; all other species average two
to a cane. This shoot bears a number of buds, each of
which may, the following season, produce another shoot, in
turn bearing fruit clusters. If all these buds are allowed to
develop, the fruit developed on the shoots will be very small.
Hence in practice it is found necessary, each year, to prune
back the current season’s growth, leaving only a few buds to
develop the succeeding year.

Grapes are commonly propagated from stem cuttings.
The European grape has been grown vegetatively for over
5,000 years.

Leaves.—The grape leaf is simple, palmately lobed or
dentate, alternate, with grooved petiole and small stipules.
The leaves of the different species vary as to size, shape,
number of lobes, nature of petiolar groove, and surface.

Inflorescence and Flowers.—The grape inflorescence is a
compact panicle. As has been indicated, the clusters are
borne at the basal nodes of the current season’s growth,
opposite a leaf or a tendril. In Vztzs labrusca, there are from
three to six inflorescences to a cane, while in all other species
the average is two inflorescences per cane.

In the wild state, grape vines are of two types: some vines
bear self-sterile perfect flowers and other vines bear only
staminate flowers. In cultivated forms, there are two types
of perfect flowers; those in which the stamens are upright
and those in which the stamens are reflexed. In the first

496 BOTANY OF CROP PLANTS

case, the pistil is fully developed and the pollen potent, while
in those flowers with reflexed stamens, the pollen is more or
less impotent. Flowers without stamens do not occur.
Among cultivated European varieties, only perfect flowers are
common. This has resulted from selection.

rea

RN.
—>stamens

Fic. 210.—Grape flower, opening. X 20.

The flowers (Fig. 210) are hypogynous and regular. The
calyx consists of a narrow rim at the base of the flower. The
corolla has five united, greenish petals; in the bud, they form
a cap (Fig. 210) over the stamens and pistils. When the
flower opens, the petals become loosened at the base but
remain united by the tips. Stamens are five in number and

VITACE 497

there is an equal number of nectar glands between. The
one pzstil is two-celled and two-ovuled. The fruit is a
berry.

Dorsey has cited marked variations in the flowers of the
genus Vitis: stamens may vary from three to nine; petals,
nectariferous glands, and carpels have a corresponding
numerical variation.

Opening of Flower and Pollination.—Flower Opening —
The opening of the grape flower is indicated by the breaking
away of the petals at the base (Fig. 210). In some instances,
all the petals break away at about the same time; at other
times, one petal may initiate the process, and be followed
by the others. The cap of five petals, adhering at their
apices, finally falls off. The rate of flower opening varies
from a few minutes to several hours. The anthers seldom
open until the cap falls off. Most grapes are insect pollinated.

Self-sterility—Many cultivated varieties of grapes are
self-sterile; this is due, for the most part, to impotent pollen.
Some cultivated varieties are perfectly self-fertile, others
partially self-fertile, and still others entirely self-sterile.
As has been indicated, perfect flowers bearing reflexed
stamens usually have impotent pollen. However, in some
cases, perfect flowers with erect stamens also bear impotent
pollen. As a rule, the self-fertile varieties, those that can
develop marketable clusters when self-fertilized, have long
stamens. Self-sterile varieties, those that cannot produce
marketable clusters of fruit when self-fertilized, usually
possess short stamens. However, long stamens and short
stamens are not absolute criteria of self-fertility and self-
sterility respectively. With but few exceptions, the strongly
self-sterile varieties are hybrids. Booth suggests that the
grape is “‘now in a state of evolution from an assumed older
hermaphrodite form to forms which are essentially staminate

32

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 fertilization. This is due to the fact that in this variety
stamens are shorter than the pistil, that the pollen has a
tendency to stick together in masses which makes its dis-
tribution less certain, and to the rather frequent development
of imperfect pollen grains. The 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: (1) staminate, and (2) self-sterile hermaphrodite.
There are no self-fertile hermaphrodites. The staminate
flowers have abortive pistils, and the so-called pistillate forms
retain their stamens, but they are abortive.

VITACE 499

Key to Most Important SPECIES OF ViTIS!

Skin of mature berry not separating freely from the pulp, Vitis vinifera
(Old World grape).
Skin of mature berry separating readily from the pulp.
Nodes without diaphragms (Fig. 207, A); tendrils forked, Vitis rotundifolia
(Southern fox grape).
Nodes with diaphragms (Fig. 207, B); tendrils forked.
Leaves and shoots glabrous at maturity and without bloom.
Leaves broader -than long; petiolar sinus usually wide and shallow,
_ V. rupestris (sand grape).
Leaves ovate in outline; petiolar sinus usually medium to narrow,
V. riparia (river bark grape).
Leaves rusty or white tomentose or glaucous blue below.
Leaves not covered with a thick, dense felt-like tomentum when
fully grown, V. estivalis (summer grape).
Leaves covered with a dense, thick, felt-like tomentum when fully
grown, V. /abrusca (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.

1The key is adapted from “The Grapes of New York,” by Hedricl.

500 BOTANY OF CROP PLANTS

Vitis vinifera is probably a native of western and southern
Asia.

Vitis rotundifolia (Southern Fox Grape).—This is usually
a very vigorous, high-climbing grape, with hard wood and
smooth bark. The leaves are broadly heart-shaped, with
coarse, blunt teeth, light green in color, smooth above and
below or sometimes slightly hairy on the veins below. The
large, spherical, black or greenish-yellow berries are in small
loose clusters. It grows wild from southern Delaware to
Missouri, Texas, and the Gulf States.

The varieties of this species are known as Muscadine
grapes. One of the chief varieties is the Scuppernong.

Vitis rupestris (Sand Grape).—This is a low shrub with small, broadly
heart-shaped, slightly lobed leaves with coarsely toothed margins. The
small, black or purple-black berries are in small clusters.

This species is southern in its distribution, reaching southern Pennsylvania
as its northernmost limit. It is very resistant to rot and mildew of the foliage.

Vitis riparia (River-bank Grape).—The river-bank grape is a rather
vigorous climbing plant with smooth and slender twigs. The leaves have
large stipules; the margin has sharp teeth that vary in size. The berries
are small, black, coated with a bloom, and occur in rather compact, but small
clusters.

This is the most widely distributed and the hardiest of American grapes.
It is common on stream banks in the United States east of the Rocky
Mountains.

Vitis aestivalis (Summer Grape).—This is a strong-growing species with
leaves that are short-stipulate, thick, three- to five-lobed, shallowly dentate,
dark green above and rusty pubescent beneath. The berries are astringent,
of average size, and usually in long clusters.

This species is native to southeastern United States. Its varieties are wine
grapes.

Vitis labrusca (Northern Fox Grape).—This is a stocky
plant with large, heart-shaped leaves which are either entire
or three-lobed, dark green above, and densely pubescent
below. The clusters of thick-skinned berries are medium
to large.

VITACEE 501

By far the greatest number of cultivated grapes are varie-
ties of this species, or hybrids from it and other species,
chiefly Vitis vinifera, the Old-World grape.

Varieties of Table Grapes.—There are four very common
varieties of table grapes:

. Catawba, hybrid of V. labrusca and V. vinifera.

. Delaware, hybrid of V. labrusca and V. bourguiniana.
. Niagara, hybrid of V. labrusca and V. vinifera.

. Concord, variety of V. labrusca.

WD H

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, Iona, 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 toro 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: (1)
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: (1) 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

VITACEE 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

Beacg, 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.
Booru, 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, 1911.
Variation in the Floral Structure of Vitis. Bul. 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.
Heprick, V. P.: The Grapes of New York. 15th Ann. Rept. N. Y. Agr.
Exp. Sta., vol. 3, part 2: 1-564, 1908.
HusmMann, Grorce C., and Dearinc, 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.
Rermer, 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
MALVACEZ (Mallow Family)

Habit——Members of the family are herbs, shrubs, or
trees. Tree species are tropical. The mallows are usually
rich in mucilage.

aK es
\\cal

\petal

‘monadelphous
Stamens

Fic. 211.—Diagram showing arrangement of parts in the cotton flower.
(After Cook, U. S. Dept. Agri.)

Leaves.—The leaves are alternate, and mostly palmately
veined and palmately lobed. The stipules are small, narrow,
and deciduous.

595

506 BOTANY OF CROP PLANTS

Flowers.—The flowers are either single or in clusters, and
are terminal or axillary. Some are subtended by an involu-
cel which resembles the epicalyx of strawberries. This
involucre (Fig. 211) consists of three or more bractlets, which
may be separate or united. In the marsh mallow (Althea),
the involucre consists of six to nine bractlets united at the

shomas——~ :

“Xx
locyles?~
wi ovules

Fic. 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 dicecious or
polygamous. There are five sepals (rarely three or four),

MALVACEE 597

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 reality
but five stamens, united by their filaments, and branched
above into numerous stalks bearing pollen sacs. This is
further evidenced by the fact that each stalk bears a single
pollen sac, a structure equivalent to one-half of a typical
anther. The stamen tube may be anther-bearing at the
summit, as in Malva, Abutilon, etc., or anther-bearing below
the summit, as in Hibiscus and Gossypium. The ovary is
several-celled. Usually, there are as many styles as cells
of the ovary; the styles are united below, and distinct above,
and generally project beyond the stamen column.

Fruit and Seeds.—The fruit is a several-celled capsule
(rarely a berry). The seeds are kidney-shaped, globose or
obovoid, and have large cotyledons and either little or
abundant endosperm.

Geographical.—Members of the family are widely distributed in tropical
and temperate regions. There are about 40 genera and 800 species.

Economic Importance.—The mallow family possesses one
of our most valuable economic plants—cotton (Gossypium).
Cotton is the chief fiber plant of the world. It is grown
throughout tropical and subtropical regions. Another crop
plant is okra or gumbo (Hibiscus esculentus). Althea
officinalis is the marsh mallow, the roots of which are used
principally for mucilage and for medicinal purposes. Orna-
mental representatives are hollyhock (Althea rosea), mallow

508 BOTANY OF CROP PLANTS

(Malva spp.), poppy mallow (Callirhoé spp.), Abutilon
and Hibiscus. The Rose of Sharon is Hibiscus syriacus.

Key To ImporTANT GENERA OF MALVACEE

Stamen column anther-bearing at the summit.
Carpels one-seeded.
Involucre of six to nine bractlets, Althea (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, Callirkoé (poppy mallow).
Carpels two- to several-seeded, Abutilon.
Stamen column anther-bearing below the summit (Fig. 212).
Bractlets of involucre, numerous, Hibiscus.
Bractlets of involucre, three, Gossypium (cotton).

GOSSYPIUM (Cotton)

Habit of Plants, and Roots.—There are more than 4o
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 214 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: (1) Vegetative branches or ‘“‘limbs,”’ and (2)
fruiting branches. ‘There are two buds at the base of each
leaf. One of these is a true axillary bud, the other one,
extra-axillary. Vegetative branches or limbs may arise

MALVACEE 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

Fic. 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.

510 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 rootscome. 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”’

F Egyptian-Upland hybrid plants may have a one-third,
two-fifths, or five-thirteenths arrangement. The phyllo-
taxy is one-third in Asiatic cottons. However, when Asiatic
species are crossed, the hybrid plants may show a two-fifths
or three-eighths arrangement. Leaf arrangement is similar
on main stem and vegetative branches, but on fruiting
branches the leaves are in two alternate rows; this latter
condition is brought about by a twisting of the joints, each
internode being twisted in the opposite direction from the
adjacent.

The leaves are petioled, stipulate, cordate as a rule, and
three- to seven-lobed, sometimes nine-lobed. Glands may
be present or absent on the leaves. When present, they
occur on the under side of the main ribs, about one-third of
the distance from the bases.

The leaves on fruiting branches are often irregular in outline
and may have one or two glands. The leaves on vegetative
branches and on the main stem are regularin 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,

MALVACEE 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.

“TIntracalicary Organs.’”-—These sometimes occur in the
cotton flower. They are a series of small greenish organs
between the calyx and corolla. There are five of these
structures, but often some of them are so small as to be visible
only by use of the hand lens. They are attached to the
calyx, and alternate with its lobes. Cook and Meade regard
them as ‘‘supernumerary calyx lobes or as representing free
stipular elements of the calyx lobes.”’

Corolla—This is hypogynous. ‘There are five petals, often
united at the base, and attached to the lower part of the
stamen tube. They are usually yellow or red in color. In
G. barbadense the petals are yellow or sulphur-colored, with a
purple spot on the claw. The petals are convolute in the
bud.

Stamens.—These are monodelphous in cotton. There are
often as many as 80 or go 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. Asa rule, there are two kinds
of hairs on the seed: (1) 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

MALVACEE 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 the two patches. ‘The lint at the tip of
the seed in some Upland cottons is longer than that at the
base.

Fiber Differences—tThe fibers of Upland cotton are 1 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 0.000640
New Orleans.......... 1.02 ©.000775
Pexasi sce 4a sete 1.00 0.000763
Uplands ¢ o:cgciuvs cit 0.93 0.000763
Egyptian............. 1.41 0.000655

Form and Structure of Fiber——Young cotton fibers are
circular in cross-section. As they increase in length, the
walls become thinner, and the fiber takes on a flattened rib-
bon-like appearance. The thickness of the walls becomes
greater when the boll opens, due to the rapid consolidation
of the liquid cell contents, which become deposited on the
inner walls. The deposition is irregular, hence the twisting
of the fiber. This twisting is a characteristic of the cotton
fiber. ‘The twist is not necessarily in one direction through-
out its length; there may be a reversal here and there.

The fiber is uniform in diameter for about three-fourths
of its length, and then tapers gradually to a point. At’the
point, it may be perfectly cylindrical and solid. The hair
cavity or lumen takes up about two-thirds of the entire

516 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, Si/k.
Does not dissolve in caustic potash.
With iodine and sulphuric acid the fiber swells and becomes green,
Hemp.
With iodine and sulphuric acid the fiber swells and becomes blue.
Immerse fiber in concentrated sulphuric acid for two minutes, wash
in water, treat with dilute ammonia, dry—fiber forms a gelatinous
mass soluble in water, Cotton.
With above treatment, fiber is not altered, Linen.

Species.— Watt, in his great work, describes 42 distinct species and varie-
ties of Gossypium. A number of them are known only in the wild state.
Gossypium, as a genus, is indigenous to tropical regions. It is now grown
under cultivation to the 40° latitude on either side of the equator.

Watt divides the wild and cultivated cotton plants of the world into five
“sections,” as follows:

MALVACEZ 517

Section I. Species with a Fuzz but 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, davidsonit,
klotzschianum, robinsoni, darwinti, tomentosum, drynarioides, harknessii, and
stocksii. The bracteoles are free, extraflora] nectaries absent, the fruit small,
and the rather large seeds have a fuzz but no lint.

Section II. Fuszy-seeded Cotlons 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. mustelinum, punctatum,
hirsutum, palmerii, fruticulosum, schottii, lanceolatum, microcarpum, peruvi-
anum, and mexicanum. G. mustelinum is a native of Brazil and Colombia.
G. punctatum is native to southern United States, West Indies, and northern
Africa. It exists in a state of cultivation in various sections. Watt considers
G. hirsutum as “only a cultivated state of G. punctatum” . . In this
country, however, the Upland cottons are all considered as offsprings of
hirsutum (Fig. 214). G. palmerii, fruticulosum'and lanceolatum are Mexican
species. G. scholtii is from Yucatan, and is known as the ‘‘split-leaved”’ cot-
ton. G. microcarpum, knowmas Ashmouni cotton and Red Peruvian cotton,
grows in Mexico, northern South America, Africa, and Malaya. It is culti-
vated. G. peruvianwm is the Peruvian or Andes cotton. Watt regards many
of the Egyptian cottons as races or hybrids of this species. G. mexicanum

518 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 the other. The long staple Upland series, chief

Fic. 214.—American upland cotton (Gossypium hirsutum). (After Watt.)

representatives of which are Allen, Peeler, Simms and Sunflower, are also
hybrids, with hirsutum characters dominant.

Section IV. Naked-seeded Cottons with the Brocteoles Free or Nearly so and
Glands Cons picuous.—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

MALVACEE 519

“naked.” To this section belong G. tailense, purpurascens, vitifolium, bar-
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. vitifolium, the vine-leaved cotton, has fur-

Fic. 215.—Sea Island cotton (Gossypium barbadense). (After Watt.)

nished a number of valuable cultivated typés in Egypt, Antilles, etc. It is
closely related to G. barbadense. G. barbadense (Fig. 215) includes the Sea
Island cottons of America and Egypt. Watt believes that Sea Island cotton
is a modern development, not indigenous to Barbados or any of the West
Indian Islands, but probably from somewhere in South America. He says

520 BOTANY OF CROP PLANTS

that “it is highly probable the modern stock is a hybrid.” The Sea Island
cottons proper which have been grown with the greatest success on the islands
off the coast of Carolina and Georgia are referred to G. barbadense var.
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
seed.

Wild Cottons.—Wild cottons all have a red-colored, hairy
coating on the testa. As is seen above, there may be fuzz
only, or both fuzz and lint, or lint alone. Cultivated cottons
have a long white lint, in both fuzzy-seeded and naked-seeded
forms. Sea Island cottons have the least fuzz of all culti-
vated forms. White lint may be regarded as brought about
by cultivation. The appearance of rust-colored fuzz or
lint may be regarded as a tendency to revert to the ancestral
type.

The reddish tint of wild cottons is due to an aggregation of
colored particles in the central core of the fiber.

American Cottons.—American authorities place the cot-
tons of the United States into two species: G. hirsutum,
American Upland cotton, and G. barbadense, Sea Island,
cotton. It has been noted above, however, that Watt claims
that our Upland cottons are hybrids between G. hirsutum
and G. mexicanum. Ninety-nine per cent. of the cotton
crop in the United States is Upland.

The most important distinction between these two species
is in staple length. The fibers of Upland cotton are from 1
to 2 centimeters long, those of Sea Island 2.5 to 4 centimeters
long. The yield of the former is greater but the quality not
so fine. The flowers are white, turning red on the second day
of blooming in Upland cotton, but yellow with a purple-red

MALVACEE 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
Carolina, Georgia, and Florida.

Types and Varieties.—Upland is the chief American cotton. It has been
divided by Duggar into a number of ‘‘groups”’ as follows:

1. Big Boll Group.—Plants vigorous and stocky; limbs strong, usually two
in number; fruiting branches strong, varying from short to long; bolls large,
45 to 68 of them yielding a 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, 33 to 35 per cent. of
seed. Earliest American cottons. Examples: King, Dozier, Hodge, Mascot.

7. Long-limbed Group.——Plants large; limbs long with long joints; bolls and
seeds medium to large; lint percentage low; fuzz of various shades. Exam-
ples: Petit Gulf, Peeler, Hagaman. This group is of little importance.

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 180 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-
Tetaining 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

MALVACEA 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 /int is spun into thread or yarn, and
woven into all sorts of fabrics. The finer threads are made
from Sea Island cotton, while ordinary threads and yarns
are from long staple upland cotton. The short lint or fuzz,

524 BOTANY OF CROP PLANTS

known as ‘‘linters,’”’ which is not removed in ginning, is
taken from the seeds and made into coarse twine, carpets,
and batting.

Cottonseed Hulls ——These are used in the manufacture of
paper and fiber board from which are made gear wheels,
trunks, etc. The hulls are also utilized as fuel and fertilizer,
and as a cattle food.

Cottonseed Oil——This is one of the most valuable products
of the cotton plant. The oil of the seed is in the embryo.
After the seed coats are removed, the embryos (“‘meats’’),
are cooked for twenty to thirty minutes to melt the oil, and
to drive off some of the water. The oil is then extracted
under pressure. A ton of seed yields about 40 gallons of
crude oil. Various grades of cottonseed oil are secured by
different processes of refining and filtering.

Cottonseed oil is now produced in large quantities in this
country. The United States exported 35,304,000 gallons
of the oil in 1913. 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,-
ooo. The death of animals sometimes associated with its
use is due to a toxic substance, gossypol. Cottonseed

525

MALVACEZ

kernels are now rendered less toxic by extracting the gossypol

with ether, or with ether and alcohol;

oe
o%
a)
exis
v0
“6
Se ai
=a
Ae
Po)

=

fo}

?

with an alcoholic solution of an alkali,

Csaaysyqng ‘Kuvguon
YOOT UDIM4IMY ‘IUDLADJIF “[ SajADYD pun upvystag Kadag 149q1V &Q ‘OI6L ‘yyst4akdoD “yoor

puoras ‘Kydnvasoay fo sypyuassy wosq) “pjiom jo suolse1 Butonpoid-w0}}0D—9Iz ‘OI1q

B24} ODay

Cottonseed meal is

gossypol and rendering it non-toxic.

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.

Fic. 217.—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 balesin 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.

Propuction or Lint (EXCLUDING LINTERS) IN 500-POUND Gross WEIGHT
BALES, BY STATES, 1915

State Bales
POXAS): pases Gkby Bue Sek ahy A oe eB S OE 3,175,000
GeORPia: 2.5 Gu cbianidedy one Caeeate x 1,900,000
South Carolina..................-..... 1,160,000
Alabama i535 55. Ge2de—. ede pdasete sax 1,050,000
MiUssISSIDPIysc05) <u Seah E teens aun 940,000
ATK ANSAS' cies ershireh ie © gah dee ee tans Beha aoe 785,000
North (Carolina)... ac¢ 4 ¢aedu eh aaa es 708,000
Oklahoma yj-633 ¢e4 ca ee hn ged eae eee ee tes 630,000
EQuislaniarciiciins scien sap en Santas Gian nase 360,000
MEONMESSEE 415. 5.2.5 5ass:aeiactod Delctos andr bg eat dl Didid de 396,000
All other States....................020- 108,000
United. States. ipa icanccccssaimese cues 11,161,000
Total value of crop................00005 $602,393,000

HIBISCUS ESCULENTUS (Okra, Gumbo)

Description.—Okra or gumbo is a stout, annual plant.
The stems are cylindrical and usually rough-hairy. The
leaves are large, heart-shaped, three- to five-lobed, and with
very prominent veins; the lobes are coarsely toothed. The
solitary, showy flowers arise in the leaf axils; they are
subtended by numerous, narrow, involucral bracts; the
calyx is five-cleft; there are five large yellow petals; the
stamens form a column which is five-toothed at the apex, and
is anther-bearing along its entire length; the ovary has five
cells, each of which has several ovules; there are five style
branches, each tipped by a capitate stigma. Okra is regu-
larly cross-pollinated by insects, chiefly bumblebees. The
fruit is a pod with five longitudinal ribs; the seeds are large
and kidney-shaped.

528 BOTANY OF CROP PLANTS

Geographical.—The original home of okra is Africa. It is now introduced’
into many civilized countries, and grown as a vegetable with particular suc-
cess in the warmer ones.

Types.—Beattie divides the varieties of okra into three
types: (1) Tall green, (2) dwarf green, and (3) lady finger.
Each of these is further divided into long-podded and short-
podded sorts. Plants of the “‘lady-finger’”’ type are much
lighter in color than those ‘of the other two types. Tall
green okras are 4 to 8 feet high, dwarf green sorts about 114
to 314 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

Bas, W.L.: The Sexuality of Cotton. Yearbook Khediv. Agr. Soc. Cairo,
IQO5.

Beattiz£, 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, rgr1r.

Cook, O. F., and Mrape, R. M.: Arrangement of Parts in the Cotton Plant.
U.S. Dept. Agr. Bur. Plant Ind. Bull. 222: 1-26, 1911.

Dimorphic Leaves of Cotton and Allied Plants in Relation to Heredity.
U. S. Dept. Agr. Bur. Plant Ind. Bull. 221: 1-59, 1911.

Cook, O. F., McLacaLan, ARGYLE, and Mane, R. M.: A Study of Diversity
in Egyptian Cotton. U.S. Dept. Agr. Bur. Plant Ind. Bull. 156: 1-60,
1909.

Duccar, 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.

FiatTers, A.: The Cotton Plant: Its Development and Structure and the
Evolution and Structure of the Cotton Fiber. London and Manchester,
1906.

MALVACEAE 529

HeizMann, H.: Die Baumwolle. Zurich und Leipsic, 1913.

MEapDE, R. M.: Methods of Securing Self-pollination in Cotton. U.S. Dept.
Agr. Bur. Plant Ind. Cir. 121: 29: 30, 1913.

Monie, Hucu: The Cotton Fiber, Its Structure, Etc. Manchester and
London, 1890.

OppeL, A.: Die Baumwolle. Leipsic: Duncker und Humblot, 1902.

PARLATORE, Fitrppo: 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.

Ty.er, 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.

Bul. 163: 1-127, 1910.

Watt, G.: The Wild and Cultivated Cotton Plants of the World. New
York and London, 1907.

34

CHAPTER XXXIV
UMBELLIFER (Carrot Family)

Stems and Leaves.—All the common representatives of
the carrot family are herbs. A very few are shrubs or trees.
The stems are usually hollow. The Jeaves 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 ‘‘ Umbellifere”’
(literally meaning umbel-bearing). In a compound umbel,
the smaller groups of flowers are designated umbellets. The
umbel as a whole is commonly subtended by an involucre,
the umbellets by an involucel (little involucre). When the
inflorescence has an involucre, it is said to be involucrate;
when it has involucels, it is involucellate.

The flowers (Fig. 218) are small, mostly regular, perfect
or polygamous, and pentamerous. In some instances, the
outer flowers of the umbel are irregular, the petals pointing
outward being somewhat larger than those pointing inward.
The calyx, when present, forms a tube wholly adnate to the

530°

UMBELLIFERZ 531

ovary; the limb of the tube is absent, or divided into five
inconspicuous teeth. The corolla consists of five separate
petals, attached to the base of the calyx tube; the tips of the
petals are usually turned in, and emarginate or two-lobed.
There are five stamens, curved inward in the young flower,
with filiform filaments and versatile anthers. The single,

°C

yt ri
\ AY yu h
| \ \) SS i carpophores

x

s dorsal rib

oil lubes. * rsal
ateral ribS <> interval

rN
eedipepodiam o. mericarps 74
Dy zinler mediate (( e ap \

-laleral nb
sf
le

commissural 3d

Fic. 218.—Parsnip (Pastinaca sativa). A, median lengthwise section of
flower, X12; B, face view of same, X12; C, dorsal view of single mericarp, x
244; D, floral diagram; E, schizocarp with mericarps separating at maturity,
xX 214; F, cross-section of single mericarp, X10. (D after Strasburger.)

inferior ovary consists of two locules, with a single seed in
each, and of two distinct, straight, filiform styles borne on a
swollen nectariferous style foot, the stylopodium (Fig. 218).
In some genera (as Apium, celery), the stylopodium is
inconspicuous or wanting. The umbellifers are usually
insect-pollinated. Protandry is common.

532 BOTANY OF CROP PLANTS

Fruit.—-The umbelliferous fruit (Fig. 218) is very charac-
teristic. It is termed a schizocarp, i.e., a dry fruit of two
carpels, these separating at maturity along the midline or
commissure into two one-seeded halves—the mericarps.
Each individual carpel or mericarp is indehiscent. The two
mericarps remain attached for a while after splitting by a
forked stalk, the carpophore (Fig. 218,E). At the summit of
the fruit is a swollen nectary, the stylopodium, giving rise
to two short, persistent, usually outwardly curved styles.
Each meticarp bears, on the outside, five longitudinal mem-
branous or corky ribs, the primary ribs. These are modif-
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 (vitta#), running lengthwise of the fruit. These tubes
contain secretions of balsams, resins, and volatile oils, which
impart to the fruit its characteristic odor and taste. The
fruit may be bristly (as in carrot) or smooth (as in parsnip,
and many others). The bristles may cover the fruit (as in
Sanicula), or be confined to the ribs (as in carrot). Oil
tubes are sometimes obsolete or obscure (as in Conium,
Hydrocotyle, Washingtonia). If distinct, they are solitary
(as in parsnip) or several (as in Angelica, Cymopterus).
There are usually two or more oil tubes on the commissural
side, that is, on the side that is contiguous with the adjoining
mericarp.

The fruit is either flattened Jaterally (at right angles to the
commissure), or flattened dorsally (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

UMBELLIFERE 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, Daucus (carrot).
Fruit not bristly.
Fruit strongly flattened dorsally, with lateral ribs more or less prominently
winged (Fig. 218, F), Pastinaca (parsnip).
Fruit not strongly flattened dorsally, usually more or less laterally flattened
(Fig. 222, B). ’
Stylopodium conical.
Involucre wanting; leaves pinnately compound.
Flowers white, Coriander (coriander).
Flowers yellow, Faeniculum (fennel).
Involucre present; leaves ternately compound, Carwm (caraway).
Stylopodium flat or wanting, A piwm (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 of the ‘carrot’ the following tissues
may be seen, from the outside to inside: (1) 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

nearer the second season of
ie growth, a rough, hispid
> : stem, 2 or 3 feet high, and
a with spreading branches,
apeary 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-
Fic. 219.—Fruit of carrot (Daucus cence is a compound
carota). A, cross-section; B, external umbel. At maturity, the
view. (A, after Sargent). B X10.
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.

UMBELLIFERE 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 (vitte) are solitary in the in-
tervals, that is, under the secondary ribs, and two are on the
commissural side of each mericarp. The seed is flattened
dorsally, and the face plane or slightly curved.

Geographical.—The wild form of Daucus 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.

A

Fic. 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 quality. As to shape of

536 BOTANY OF CROP PLANTS

the vegetable, varieties may be divided into two groups
(Fig. 220).

1. Roots distinctly pointed, tapering (Long Orange, Saint
Vallery).

2. Roots blunt at the tip, not pointed (Early Scarlet
Horn, Ox-heart, Chantenay, Stump-rooted Half Long Red).

The roots may be white (Large White, White Vosges,
White Belgian), red (Carentan), orange or orange red (Early
French Forcing Oxheart, Long Orange), or purple-violet
(some Egyptian and Spanish varieties).

Uses.—Medium-size carrots, particularly those with yellow
or orange flesh, are used as a table vegetable and for the
seasoning of soups and stews. The larger, coarser varieties,
such as Large White, Large Yellow Belgian, Danvers and
White Vosges, are grown for feeding stock during the winter
season. The yellow coloring matter, carotin, is sometimes
extracted from the roots and used for coloring butter.

PASTINACA SATIVA (Parsnip)

Habit, Roots, and Stems.—The parsnip is of either
annual or biennial duration. When grown from seed, a
fleshy hypocotyl and tap root are first formed; these consti-
tute the “‘parsnip”’ vegetable. In the wild form, the root
and hypocotyl are thin, tough, and woody. During the
second season, a branching stem is sent up to a height of from
2 to 3 feet. The tall, erect stems are grooved, smooth or
somewhat downy pubescent, and become hollow.

Leaves.—The lower and basal leaves are petioled, pinnately
compound, the thin segments ovate or oval, lobed, incised
or dentate. The upper leaves are sessile, much smaller than
the lower, and not so deeply lobed. The terminal leaflet of
each leaf is usually three-lobed.

UMBELLIFERE 537

Inflorescence and Flowers.—The flowers (Fig. 221) are
in broad compound umbels usually with 7 to 15 main “‘rays,’’
each terminated by a small umbellet. There are no involu-
cres and involucels in the parsnip, thus differing markedly

Fic. 221.—Leaf and inflorescence of parsnip (Pastinaca sativa).

from the carrot. The flowers are yellow. The calyx teeth
are very small or absent, the petals incurved and small, the
stylopodium depressed, and the ovary inferior.

‘Fruit and Seed.—The fruit (Fig. 218) is broadly oval and
much flattened dorsally. The dorsal and two intermediate

538 BOTANY OF CROP PLANTS

primary ribs are thread-like, while the lateral ribs are expanded
into broad, flat wings, with those of the two mericarps con-
tiguous. The oil tubes are solitary in the intervals; there
are four on the dorsal side and two to four on the commissural
side. The olive-green seeds are flattened dorsally. The
seeds are very short-lived.
Geographical.—The wild parsnip, Pastinaca sative, from which our culti-
vated varieties are derived, is a native of Europe. This wild form has be-

come naturalized in many sections of North America, occurring as a weed
along roadsides and in waste places.

Varieties.—There are comparatively few parsnip varieties.
Probably the most popular sorts are the Guernsey and Hollow
Crown. In both of these, the crown is concave.

Fic. 222.—Celery (Apium graveolens). A, schizocarp, external, x 15; B,
diagrammatic cross-section of schizocarp, xX 20.

APIUM (Celery and Parsley)

Generic Description.—Members of this genus are annual
or perennial herbs with pinnately divided leaves. The white
or greenish flowers are in compound umbels. The involucre
and involucels may be present or wanting. The calyx teeth

UMBELLIFERE 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 18 species in this group, distributed chiefly
in the Eastern Hemisphere. There are two well-known cultivated species
(parsley and celery) both of which are natives of Europe, and an indigenous

species, Apium leptophyllum. These three species are distinguished in the
following key.

Kry TO PRINCIPAL SPECIES OF APIUM

Flowers greenish-yellow, A pium petroselinum (common parsley).
Flowers white.
Leaf segments broad, A pium graveolens (celery and celeriac).
Leaf segments narrow, A pium 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, 1 to 3 feet
high. The upper leaves are also bipinnate, but the seg-
ments are linear-oblong and entire.

The inflorescence is a compound umbel with linear involu-
cral bracts and awl-shaped involucellate bractlets. The
flowers are greenish-yellow. The fruit is ovate, smooth, and
with pronounced ribs.

When large parsley seed is used the plants from them have
larger and earlier foliage and are more capable of renewing the
tops after being cut back than plants from small seed.

Varieties.—As to leaf characters, there are two types of
parsley:

540 BOTANY 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 1 to 3 feet high. The leaves are
pinnately compound with three to five oval, coarsely toothed
or incised leaf segments. The small white flowers are in
umbels. Involucre and involucels are small or wanting.
The fruit is oval, flattened laterally, and has corky ribs.
The oil tubes are solitary in the intervals and two in number
on the commissural side.

Geographical.— A pium 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: (1) 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-

UMBELLIFERZ 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: (1)
self-blanching varielies—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

Fic, 223,—Celeriac (Apium graveolens). (After Vilmorin.)

light; the leaf blades, however, are permitted to grow in the
light, so that the processes of food-making proceed in a
normal manner, and the stalk is not stunted. Chlorophyll
is formed only in those parts of the plant exposed to the
light directly. Boards, paper or earth are placed about the
stalks to exclude the light.

(2) Green or winter varieties—not as quick-growing or
easily blanched as those of the preceding type and, further-

542 BOTANY OF CROP PLANTS

more, with better keeping qualities when stored for the winter
(Giant Pascal, Boston Market, Winter Queen, Giant White
Solid).

All cultivated varieties of celery require cool weather and
plenty of moisture for their best development; they are
intolerant of excessive heat. Celery culture is carried on
with the greatest success on reclaimed muck soils in regions
with a cool climate.

Uses.—Celery is grown principally for the thick, fleshy
leaf stalks. The leaves are also used for garnishing and
seasoning, and the seeds are used for flavoring salads and
soups. The fleshy root of celeriac is used as a flavoring or
is stewed separately.

References

Coutter, J. M., and Rose, J. N.: Monograph of the North American Um-
bellifere. Contr. U.S. Nat. Herb., 7, No.1: 1-256, 1900.

CHAPTER XXXV
VACCINIACEZ (Huckleberry Family)

This is a widely distributed family occurring in tropical,
temperate, and arctic regions. It is closely related to the
heath family (Ericace@) which possesses such well-known
plants as kinnikinic (Arctostaphylos uva-ursi), the creeping
wintergreen (Gaultheria), American Laurel (Kalmia), Labra-
dor tea (Ledum), Azalea, Rhododendron, and trailing arbutus
(Epigea 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 fiye-celled, or sometimes eight- to ten-celled by
false partitions.

Habit.—The plants belonging to this group are erect or
prostrate shrubs or, in a few instances (e.g., Vaccinium
arboreum, the farkleberry) a small tree. Some South
American species are epiphytic.

Leaves.—The leaves are simple, alternate, often thick
and leathery and sometimes evergreen, and without stipules.

Inflorescence and Flowers.—The flowers are solitary in
the leaf axils (as in Chiogenes hispidula, the creeping snow-

543

544

BOTANY OF CROP PLANTS

berry, or Vaccinium membranaceum, the thin-leaved_ bil-
berry), or in racemes (as in Vaccinium virgatum, southern

Fic. 224.—Floral
diagram of Vaccin-
ium.

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

es with
ovules

Fic. 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

VACCINIACEE 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.

VACCINIUM

The representatives are shrubs or small trees. The leaves
are leathery. The flowers are solitary or in short racemes.
They have characters as described above under the family.

Pollination.—Coville describes the method of pollination
in a blueberry. It is quite probable that this will hold true
for most Vaccinium species. The bell-shaped flower is in-
verted, the 10 stamens hang downward and are shorter than
the style. The flat filaments form a close circle about
the style, being held together by the interlacing mar-
ginal hairs. When an insect visits the flewer, the only easy
way it can get at the nectar, which is situated at the base of
the stamens on their inner side, next to the style, is to push
its proboscis between the anther tubes. In this process, the
mature pollen grains are shaken loose, and some of them stick
to the insect’s body, to be carried by it to flowers-visited sub-
sequently. The anther pores open inward. The stigma is
top-shaped and the very apex is the only receptive portion.
Hence the rim of the stigma just below the receptive surface,
prevents the falling pollen from reaching this surface. In
this way self-pollination is to a large extent prevented.

If pollen from the same plant is used in pollination, the fruit
that is formed remains small and green, and later drops off.

35

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. 3

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-id@a (cowberry, mountain cranberry, foxberry).
Stamens exserted.

Leaves ovate, acute at the apex; stems slender, creeping; berries
globular, V. oxygoccus (small cranberry).

Leaves oval or oblong, obtuse or retuse at the apex; stems stout,
creeping, with ascending branches; berries egg-shaped or oblong, V
macrocar pon (American cranberry).

Fruit blue or black in color.
Plants low, seldom over 2 feet tall.
Leaf surfaces free of hairs.
Berries blue.
Leaves shining above, V. cepitesum (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. angustifolium (low blueberry).
Fruit without bloom, V. nigrum (low black blueberry).
Leaf surfaces hairy, V. canadense (Canada blueberry).

VACCINIACEE 547

Plants tall, 3 to 12 feet, and spreading.
Flowers solitary in leaf axils, V. ovalifoliwm (tall or oval-leaved bilberry).
Flowers in groups in leaf axils.
Fruit blue, V. corymbosum (high-bush blueberry, swamp huckleberry).
Fruit black, V. atrococcum (black blueberry).

GAYLUSSACIA (Huckleberry, Tangleberry, Dangleberry)

Description.— Members of this genus are shrubs with alter-
nate and entire or finely toothed leaves. The inflorescence is
araceme. The small white or pink flowers are on two-brac-
teolate pedicels. The calyx tube is short, five-lobed or
five-toothed, and persistent. The stamens are 10 in number,
and their anthers open by terminal pores. The /ruit-is
described as a berry-like drupe, or 10-celled drupe- with ro
seed-like nutlets. The ‘‘seeds’’ are each covered with
endocarp.

Geographical.—The genus is distributed throughout North and South

America. It possesses about 40 species. There are five species of Gaylussacia
growing in North America.

Key to NortH AMERICAN SPECIES OF GAYLUSSACIA

Leaves evergreen, finely toothed, G. brachycera (box-huckleberry).
Leaves deciduous, entire.
Fruit with a bloom, G. frondosa (blue huckleberry, tangleberry, dangle-
berry).
Fruit without a bloom.
Leaves 2 to 4 inches long, G. ursina (Carolina huckleberry).
Leaves 1 to 2 inches long.
Bracts small, deciduous, G. resinosa (black or high-bush huckleberry).
Bracts large, persistent, G. dumosa (dwarf or bush huckleberry).

Of the above species, G. resinosa is, as a rule, the common
black huckleberry on the market. This species isa shrub, 1
to 3 feet high, with stiff branches, oval or oblong leaves that
are very resinous when young, a few pink or red flowers and
sweet, seedy, black fruit. It grows in sandy soil from New-
foundland to Georgia, westward to Kentucky and Manitoba.

548 BOTANY OF CROP PLANTS

CRANBERRIES

Some botanists place the cranberries in the genus Oxycoc-
cus, separate from the blueberries, huckleberries and _bil-
berries, which are included in the genus Vaccinium. In
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

Fic. 226.—American cranberry (Vaccinium macrocarpon).

cranberries grown in America: American cranberry (Vac-
cinium macrocarpon) and the small cranberry (Vaccinium
oxycoccus). These are distinguished in the key above. It
seems that the appearance of the flower in the bud has prob-
ably suggested the name cranberry or “‘craneberry.” Just
before the flower opens, the pedicel, calyx and corolla resem-
ble the neck, head, and bill of a crane.

Vaccinium macrocarpon (Large or American Cranberry).—
This is a low, slender, creeping plant with oblong or oval

VACCINIACEZ 549

leaves, whitened beneath, and with rolled margins. The
flowers are on short upright one-year-old shoots; they
occur in very short clusters; the corolla is light pink. The
berry is red, ovoid, oblong, or almost globular. At the
summit of the fruit, are four persistent, short calyx lobes,
bent inward.

This species is found wild in boggy land in the northern
part of the United States, adjacent Canada, south along the
eastern coast to Virginia and North Carolina. It is also
found in South 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 isa slender, creeping plant
with thin stems, 4 inches to 1 foot long, and with ovate, acute
or acuminate leaves, dark green above, whitish beneath.
The flowers are very similar to those.in the preceding species.
The berry is red, globular, four-celled, and often spotted when
young; it is smaller than that of the American cranberry,
although considered by some of superior quality.

The small cranberry is a native of alpine and subarctic

550 BOTANY OF CROP PLANTS

regions of Asia, Europe, and America. It is not cultivated
in America to any great extent.

Vaccinium vitis-idea (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 10 seeds in each fruit, and although not as
numerous as in the berry of Vaccinium, are more trouble-
some. There are two general types of blueberries: high-
bush blueberries (V. corymbosum, and V. atrococcum),
and low-bush blueberries (V. canadense, V. angustifolium,
V. nigrum, and V. vacillans).

The common black huckleberry on the market is Gaylus-
sacia resinosa. Vaccinium angustifolium is a rather common
low-bush blueberry, while V. corymbosum is the species most
desirable for cultivation.

References

Covit1e, FrepERicK V.: Experiments in Blueberry Culture. U.S. Dept.
Agr. Bur. Plant Ind. Bull. 193: 1-100, 1910.

Davis, W. T.: High-bush Blueberries. Proc. Staten Island Assn. Arts and
Sci., 2: 63-64, 1909. (

CHAPTER XXXVI
OLEACEZ (Olive Family)

Family Description.—This is a family of trees or shrubs.
The leaves are opposite, exstipulate, and simple or pinnately
compound. The inflorescence is a panicle, raceme, cyme or
fascicle. The flowers are regular, and polygamous or
dicecious; the small calyx is four-lobed, sometimes entirely
absent; the regular corolla is four-parted, or of four distinct
petals, or absent. There are two stamens, attached to the
corolla or to the receptacle. The single pistil is compound,
with a two-celled ovary, in each of which there are a few
seeds, a short style, and capitate stigma; sometimes the
style is absent. The fruit is either a capsule, samara, berry,
or drupe.

Geographical, and Economic Importance.—There are
about 21 genera and 500 species distributed widely in tem-
perate and tropical regions. The most important repre-
sentative is the olive (Olea europea). Other well-known
members of the family are the lilacs (Syringa), privet (Ligus-
trum), Jessamine (Jasminum) and ash (Fraxinus).

OLEA EUROPA (Olive)

Description.—The common olive is a small tree 20 to 25
feet high. All fruit is borne on two-year-old wood, and the
same wood never bears twice. The lanceolate leaves are
leathery, evergreen, entire, smooth, scaly, and arranged op-
positely on the stem. The flowers occur in axillary racemes as
a rule, although terminal inflorescences are more or less fre-
quent. The flowers are usually imperfect. The small calyx
is four-toothed, the corolla four-cleft, white or whitish, the
stamens two, and the pistil one. The fruit is a purplish drupe.

551

552 BOTANY OF CROP PLANTS

The olive is probably a native of the Mediterranean region.
Its cultivation in this country is confined almost entirely to

Fic. 227.—Olive (Olea europcea). Branch and fruit. (From Calif. Agr.
Exp. Sta.)

the warm, dry portions of California. The olive requires a

mean annual temperature of 57°F., and it is claimed that at

no time should the temperature go below 14°F.

OLEACEZ 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 1 or 2 feet,
each split lengthwise, and planted horizontally with the
bark up. Sprouts readily arise from the section of trunk,
and such sprouts may be allowed to continue their growth
where they are, or be made into green cuttings.

Uses.— Olives are eaten either in the green or ripe state.
They are usually “pickled,” and left whole, or “stuffed.”
Olive oil is an important commercial product. The best
quality 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 hydraulic pressure; this process gives an oil known
as “olive oil foots.” It is employed in the manufacture
of soaps, particularly castile soap, and as a lubricant. An
oil is also extracted from the seeds. It is much like that
from the pulp.

CHAPTER XXXVII

CONVOLVULACEZ (Morming Glory Family)

climates. There are close to goo species in 400 genera. A
man-of-the-earth (Ipomea pan-
: ~4--corolla bona-nox), morning glory

bindweeds (Convolvulus spp.).
twining or trailing herbs; some
ee ae ene eee Leaves.—The leaves are alter-
Inflorescence and Flowers.—The flowers are in an axil-
the ovary, five-parted or five-divided, usually persistent, and
campanulate, or tubular, with a five-angled, or five-lobed, or

The representatives of this family are found chiefly in warm

number are of economic importance, among which may be

mentioned the sweet potato,

“a durata), used as food by the

| Indians, moon-flower (Ipomea

Ue (Ipomea purpurea), cypress vine

(Quamoclit quamoclit) and the

Habit.—Most of the repre-

sentatives of this family are

tropical species are shrubs or

trees, often with a milky juice.

potato (Ipomeea batatas),length- nate, exstipulate, entire, den-
wise section. (After Sargent.) tate. lobed. or dissected
? ’ =

lary cyme, or sometimes solitary. They are regular, perfect

and sympetalous (Fig. 228). The calyx is attached below

imbricated in the bud. The corolla is plaited, convolute, or

twisted in the bud, and becomes funnel-form, salver-form,

entire limb (Fig. 228). The five stamens are inserted on the

554

CONVOLVULACEZ 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, Ipomea.
Stigmas two, filiform or oblong, Convolvulus.

IPOMGA 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

556 BOTANY OF CROP PLANTS

sympetalous corolla is 1 to 2 inches wide, funnel-form, and
has a five-lobed limb, and plaited tube. The corolla is folded
longitudinally and twisted usually to the right in the bud.
The stamens are as given under the family description. The
two- to four-celled ovary has a thread-like style which bears
one or two stigmas. The fruit is a capsule.

In northern latitudes, the sweet potato rarely blossoms,
and never matures seeds.

Geographical, and Environmental Relations. —The original
home of the sweet potato is the West Indies and Central
America. Since the sweet potato is of tropical origin it is
largely grown in the Southern States, the five leading ones
being North Carolina, Georgia, Alabama, Louisiana and
Mississippi. Ample sunshine and high temperatures favor
its growth. Although a heavy rainfall is desirable during the
first part of the growing season, the maturing of the roots
proceeds best with rather dry weather. They do best in
well-drained, light soils.

Closely Related Species.—The southern, juicy varieties of sweet potatoes
are called ‘“‘yams.” They should not be confused, however, with the true
yams, or Chinese potatoes of commerce, which belong to the species Dioscorea
batatas, in a family (Dioscoreacez), 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: (1) 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)
““Vams’’ 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

CONVOLVULACEE Bey

sorts (‘‘yams’’) are Triumph, Nancy Hall, Dooley Yam,
Vineless Yam, Sugar, Southern Queen, Florida.

Adee

Fic. 229.—Types of sweet potatoes (Ipomoea batatas). A, Black Spanish;
B. Shanghai; C, Big Stem Jersey; D, Red Bermuda; E, Southern Queen.
(Modified after Corbett.)

QD ge

Fic. 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.)

2

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

558 BOTANY OF CROP PLANTS

side near the apex (Fig. 230, B) (Delaware, Early Golden, Yellow Jersey,
Red Bermuda).

3. Leaves lobed (Fig. 230, C) (Barbadoes, Sugar, Yellow Yam, Vineless
Yam).

Sweet potato varieties may have skin color that is white, straw, red, or
purple.

1. Skin white (Vineless Yam, Early Golden, General Grant).

2. Skin straw (Orange, Delaware, New Jersey).

3. Skin red (Pumpkin, Red Bermuda).

4. Skin purple (Black Spanish, Brazilian).

Uses.—Sweet potatoes are used chiefly as a human food.
Some of the coarser varieties are grown for hog pasture. The
vines have some value as a stock food. Flour, starch, glu-
cose, and alcohol are minor products of the root. Small-
sized sweet potatoes, known as “‘seconds,’”’ are canned.
Kiln-dried sweet potatoes produce a product very similar to
corn meal in its chemical composition.

References

Grotu, B. H. A.: The sweet potato. Contrib. Bot. Lab. Univ. of Pa., 4:
1-104, IQII.

CHAPTER XXXVIII
SOLANACEZ (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
(A tropa 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 calyw is inferior, and usually
with five united lobes. The corolla is sympetalous, mostly
five-lobed. The corolla varies considerably in shape: rotate
(tomato), bell-shaped (Physalis), funnel-form (Lycium vul-
gare), salver-form or tubular (Petunia spp.) There are as
many stamens as corolla lobes, alternate with them, and
inserted on the tube; in most genera, the stamens are all
equai 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,
Nicotiana (tobacco).
Flowers solitary; stamens very unequal, Petunia (petunia).

SOLANUM

Habit.—The Solanwms are either erect herbs (as S. nigrum,
the black nightshade, and the common potato, etc.), or
climbing herbs (S. dulcamara, bittersweet). In most species,
the stems and leaves bear a stellate (star-shaped) pubescence.

Leaves.—The Jeaves are alternate, exstipulate, and lobed
or pinnately dissected.

Inflorescence, and Flowers.—The inflorescence is cymose
(bittersweet), umbellate (black nightshade), racemose (S.
carolinense, horse nettle), or rarely paniculate. The flowers
(Fig. 232) are perfect and regular; in color, they are white
(S. tuberosum varieties and S. nigrum), blue (S. eleagni-
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-eleft. The corolla is rotate or rarely broadly bell-
shaped, the tube very short, the limb plaited, five-angled or
five-lobed. There are five stamens inserted on the throat of
the corolla (Fig. 232); the filaments are short, the anthers
converge around the style, and are usually dehiscent by a
terminal pore, sometimes by a short introrse terminal slit,
and sometimes longitudinally. The ovary is superior, usu-
ally two-celled; its style is slender and simple, and the
stigma terminal.

Fruit.—The fruit is a many-seeded berry; the calyx is
persistent at the base, and in some species (S. rostratum)
encloses the berry.

Geographical.—There are about 900 species of Solanum, widely distributed,
but most abundant in tropical America.

Key To ImporTANT SPECIES OF SOLANUM

Not tuber-bearing.
Plant not prickly or spiny.
Erect herbs or shrubs.

Fruit ovoid or egg-shaped, yellow with purple or violet streaks or
splashes, often 4to 6 inches long, S$. muricatum (pepino, melon
pear).

Fruit a small, spherical berry, not over 1 inch in diameter.

Peduncles one- to three-flowered; ripe berries green, S. triflorum
(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, 5S. carolinense
(horse-nettle).

Flowers purplish; fruit large, S. melongena (egg plant).

36

562 BOTANY OF CROP PLANTS

Berry enclosed by calyx, S. rostratum (sand bur, buffalo bur).
Tuber-bearing.*

* Nore.—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. tuberosum (common potato).
Leaves elongated, S. immite.
Points of sepals long, not tapering much; leaves oval, S. chiloense.
Points of sepals short.
Anthers straight, smooth, somewhat elongated, S. ztile.
Anthers swollen, roughened, S. maglia.
Corolla star-shaped, S. jamesii, S. commersonti, etc.

SOLANUM TUBEROSUM (Potato)

This species includes all the varieties that are of value for
food. They are usually called Irish or common potato, but
also white, English, and round potato.

Habit.—The potato is a branched, more or less spreading
herb, growing to a height of 2 to 5 feet or more. It has
annual aerial stems, but is practically perennial by means of
its tubers or underground stems.

Roots.—Upon the whole, the development of the root
system is less pronounced than in most other crops. The
roots are fibrous and fine. They penetrate the soil to a
depth of 2 to 4 feet and frequently extend horizontally 2
feet or more from the plant.

Stems.—Potato stems are of two general kinds as to
medium in which they grow: Underground and aerial. The
underground stems (Fig. 12) are slender rhizomes, or are
swollen to form tubers (‘‘potatoes”). The aerial stems are
the ordinary foliage-bearing stems. ‘The discussion of
rhizomes and tubers is given on pages 29 and 31.

Stem (aerial) —The aerial or foliage stem of the potato
is herbaceots and generally erect when young, but usually

SOLANACEAE 563

becomes spreading later. It is smooth and generally solid.
It has no ribs at first, but as it develops, it becomes more or
less quadrangular.

Leaves.—Potato leaves are compound pinnate, with more

Fic. 231.—Flowering branch of potato (Solanum tuberosum).

or less petioled leaflets. The petiole bears a number of
supplementary leaflets which vary in number and importance
with the age of the plant. The rachis is decurrent (Fig. 12)
on the stem. ‘The leaflets are oval, acuminate, and the base
heart-shape or oblique in shape. The leaves as well as the
stems are characterized by a narcotic smell. At the begin-

564 BOTANY OF CROP PLANTS

ning of their development, the leaves are often simple, but
they increase in complexity with age. The single terminal
leaflet, which frequently appears alone, is soon followed by
two lateral leaflets, and these by others, so that the leaf soon
becomes distinctly pinnatifid.

Considerable differences have been found to exist in the
appearance of the leaves of the different agricultural varieties.

Flower (Fig. 232)——The corolla is tubular, with five lobes.

celled ovary

_— persis ent NW
—

Calyx

Fic. 240 —‘Botate. Galan tuberosum). A, berry; B, flower in median
lengthwise section; C, floral diagram.

It is white, yellow, purple, or blue in color and 1 to 114 inches

in diameter. There is a single whorl of five stamens which al-

ternate with the corolla lobes, and are attached to the tube.

The stamens are straight, and bear erect, yellow anthers which

are longer than the filaments and open only at the top.

Two kinds of pollen grains have been observed. Those of
most varieties are variable in size, irregular in shape, rough-
ened, and largely impotent. Those of the other type are
smooth, spherical, and potent. The latter kind are found
only on varieties which bear fruit. Some varieties produce
both kinds of pollen grains, but such plants do not always

SOLANACE 565

produce fertile flowers. Hence while the presence of round
pollen grains seems to be necessary to the production of fruit,
their presence by no means assures that the ovary will be
formed or fruit produced. The ovary consists of two carpels
with numerous ovules in each locule.

Opening of Flower and Pollination.—-The anthers are
mature at the same time that the stigmas are receptive. The
flowers have been found to open between 5 and 6 o’clock
a.m. The pollen is usually shed on the second day of bloom-
ing, and at this time, the pistil is most receptive. The an-
thers open at the top by a pore and, in some cases, split for a
short distance. The pollen is carried by the wind. The
flowers produce no nectar and are not visited by insects to
any extent, although several species of insects have been re-
ported as visiting the flowers. East concludes from obser-
vations of his own (and of others) that self-fertilization is
natural to the species. The flowers wither about the fourth
day, in the profuse-seeding varieties.

Some writers report that fragrance is correlated with pollen
yield, but East says he found no noticeable fragrance in
American varieties. It is commonly thought that potatoes
do not fruit as freely now as formerly, due to the fact that
large production of tubers has caused a degeneracy in seeding
power. While many of the varieties seldom bloom, and more
rarely set seed, some of the best varieties bloom freely and
under proper conditions set seed. Fraser says, as a result of
working with 300 varieties, many of which were grown for
several years, that it is seldom that a variety will not bloom
at some time in its life and, furthermore, he found that many
of the heaviest yielding varieties bloomed as freely as those
of less value.

In many varieties, the flowers do not open. In the Pearl
variety, Fitch finds that tuber productiveness ‘‘is universally

566 BOTANY OF CROP PLANTS

proportionate to the sexual development of the plant; that
the most degenerate tuber is produced on the plant which
carries fully developed flowers and virile pollen; while those
plants on which only female portions of the flowers appear to
be fully developed, produce tubers intermediate in form and
yield, and that the best tubers and the largest yield are pro-
duced by the type of plant whose flower buds do not even
swell.’ Furthermore, these buds do not show any other
color than green and they soon wither and break off.

Fruit.—The fruit (Fig. 233) is a globular or short oval
berry with two locules containing numerous seeds attached
to the thick axil placenta and embedded in a green acrid
pulp. The fruit is called by various names, such as “‘potato
ball,’ “potato apple,” or ‘‘apple,’”’ but is commonly referred
to as the ‘‘seed ball.”” In color the seed balls are brown,
purplish green, or green tinged with violet. Single fruits may
contain from a few to as high as 200 or 300 seeds, but some-
times no seeds are produced. Fitch found no seeds in 650
seed balls of Early Rose. One seed ball from a Pearl crossed
with a Rural contained no seed, while six seed balls of the
reciprocal cross all bore abundant seeds. Removal of the
early tubers induces fruit-bearing, while removal of the
flowers is said to encourage tuber development.

Seéd.—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.

Fic. 233.—Potato seed balls, showing a cluster, and lateral, sectional and
basal views. (After Stuart, U. S. Dept. of Agri.)

567

568 BOTANY OF CROP PLANTS

The primary root appears first, soon becomes curved, and is
followed by the axis of the hypocotyl. The cotyledon leaves
are smooth, oval, and more or less elongated, while the first
foliage leaves are provided with unbranched hairs.
Development of the Seed-
ling.—From_ the ‘thirty-sev-
enth to the fifty-sixth day
after seeding, the stolons
arise (Fig. 234); the first
pair comes from the axils
of the cotyledon leaves.
These slender cylindrical
stems possess small rudi-
mentary leaves. They trail
along on the ground and
finally penetrate the soil.
When their tips strike the
ground, they begin to swell
and form tubers. Hence the
first tubers of the plant,
grown from seed, are de-
Pic. 234-— Young potato plant sto veloped at the tips of slender,
stolons coming from the axils
of the cotyledon leaves. Roots soon arise from the stolons.
Secondary stolons appear in the axils of the first foliage leaves.
Tubers from Seedlings.—Tubers produced on seedlings
are usually small.the first year. However, Frazier reports
a tuber weighing over 7 ounces that was formed the first
year, and says that the Burbank potato was full-sized the
first year from seed. It is reported from Svalof (Sweden)
that tubers usually attain normal size and type after about
the third year from seed.
Tuberization.—It has been noted previously that tubers,

SOLANACE 569

developed on a plant grown from seed, come at the tips of
stolons arising on. the stem above ground. However, when
the tuber as a cutting is used in propagation, the young
tubers form at the ends of long, thin rhizomes (underground
stems) which arise underneath the ground from the main
axis or stem (Fig. 12). The length of the stolon seems to
be constant and a strong variety characteristic. In culti-
vated varieties, it should not exceed 3 or 4 inches. In S.
commersonii, it is reported as sometimes reaching a length
of 10 feet. The tubers or swollen stems bear a number of
buds, and these buds send out sprouts when the tuber is
planted.

As a rule, the tubers are formed beneath the ground as
noted above; but in abnormal cases, or when disturbed by
diseases, the above-ground stems may produce tubers. For
example, when the fungus, Riizoctonia, 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 facilitated 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 formation
of tubers may result when the osmotic pressure in the cul-
tural medium is high. However, this alone does not appear
to be the only determiner, since different results follow the
use of glucose and glycerine solutions of equal pressure. It
certainly seems that plenty of sugar must be present for
starch formation, and perhaps also for tubers to form. From
this fact, that a more concentrated cell sap is usually present
in fungi than in other plants, it does not seem unreasonable
to suppose that the réle of fungi in tuberization consists in
raising the concentration of the media which they enter. It
has actually been found that cultures of Fusarium in macer-
ated potato tuber preparations increase the concentration.
In this connection, it is suggested that low temperatures and
dryness of soil may induce tuberization through increasing
the concentration of cell sap.

History.—It seems ‘“‘that the potato was cultivated and
utilized by the Chilean and Peruvian people before the
arrival of the Spaniards. In 1533, Pizarro found the Chileans

SOLANACE $71

using the tubers of a plant as their principal food. There is
no evidence that he or his party introduced them into
Europe.”

Wild plants have been found on the Peruvian coast, on
the mountains of Chile, Central America, Mexico, and
southwestern United States. However, without a doubt

A
ad’
- 2s
Asie 1

at

ey ve

i ce tech ! ate

Fic. 235.—The wild potato of southwest United States (Sistannies jamesii).
(After Fitch, Colo Agr. Exp. Sta.)

those which were introduced into Europe were from culti-
vated plants and not from wild tuberous American species.
There is little doubt that South America, in the neighborhood
of Quito, is the place from which the potato was first intro-
duced into Spain early in the Sixteenth century.

After a careful study of all possible available types and
species of Solanum, and a perusal of the available literature
and records, F. Berthault has come to the conclusion that
S. tuberosum is characterized and differentiated from all
other wild tuberous Solanums by its floral characters, notably
its rotate corolla, and its calyx which is always mucronate
(sharp-pointed). All agricultural varieties of the cultivated

572 ne BOTANY OF CROP PLANTS

plant (potato) have been found to:correspond to these
characters. --.

Varieties.—There are at the present time over 500 named
varieties of potatoes in the United’ States. Many of these
variety names are found to belong to potatoes which are
identical in all respects. Usually, new varieties are the
seedlings of established varieties.

The latest attempt at a classification of American potatoes
is that of Stuart. In his ‘proposed system of classification”

_——periderm

Fic. 236.—Diagrammatic section of potato tuber.

he gives the following “groups”: Cobbler, Triumph, Early
Michigan, Rose, Early Ohio, Hebron, Burbank, Green
Mountain, Rural, Pearl, and Peachblow. Tuber, sprout
and flower characters are made the bases of distinction of
the groups. The student is referred to Bull. 176, U. S.
Dept. Agr. (Professional Paper) for the descriptions of these
groups. Fitch has also proposed a classification using about
the same characters.

Tuber Morphology.—The potato tuber is made up of a
number of zones or layers which are commonly grouped as
follows (Figs. 236 and 237):

t. Periderm or skin.

2. Cortex.

3. Vascular ring.

SOLANACE S73

4. External medulla.

5. Internal medulla.

According to Coudon and Boussard, these zones (except-
ing vascular ring) are proportioned (by volume) as follows:

Per cent.
Skin (average of two varieties)............... 8.79
Cortex (average of two varieties)............. 36.19
External medulla (average of five varieties)... 34.17
Internal medulla (average of five varieties)... . 14.95

: —periderm

_outer
cortex

_inner
cortex

“

Fic. 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 split off, giving some varieties a
characteristic rough appearance. The cells of the different
layers of periderm vary in size and shape in different varieties.
The number of layers is usually 7 or 8, but it varies from 5
to as many as 13 and even 17. At the eyes, the periderm
(skin) becomes thicker. Lenticels are scattered over the tuber.

Some claim is made that thick-skinned varieties are of
better quality than thin-skinned ones, but such is not always
the case. A netted or rough skin develops on tubers of some
varieties as they mature in storage, which suggests, that a
rough or netted skin in these cases denotes maturity. Pos-
sibly this is sometimes the source of the common idea that a
rough-skinned potato is of superior quality. The size and
type of netting is found to vary with the variety and the con-
ditions under which grown. Smoother skins are usually
found on potatoes grown on sandy soils than on those grown
on heavy soils. It has been found that the thicker and
rougher-skinned varieties stand up better in shipping, and are
preferable for this purpose even though they may have no
greater merit in other ways.

SOLANACE 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, z.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
quality. 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. Asa 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,

SOLANACEE 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 noticeably in
vigorous and in degenerate tubers. In the latter, it is
stronger and has a tendency to be longer.

Careful study shows that the buds or ‘‘eyes”’ are arranged
alternately and at the same time spirally on the tuber. Be-
ginning at one end of a tuber and proceeding toward the
other end, at the same time turning the tuber, usually enables
one to follow clearly the spiral arrangement.

The so-called “seed end,” “rose” end, or “‘crown”’ of the
tuber is opposite the point of attachment to the stem.
The ‘‘stem” end is at the “base” or heel of the tuber.
The eyes are more numerous and more vigorous at the
seed end. Ordinarily, the terminal bud (at the “seed
end’’) is the strongest and under proper conditions will be

37

578 BOTANY OF CROP PLANTS

the only one to develop. The sprout produced 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 quality, since the poorer zone of the potato (in-
ternal medulla) extends a branch to each eye, thereby in-
creasing the percentage of internal medulla at the expense
of the two outermost valuable layers.

Germination or Sprouting of Tuber—Potatoes 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 accordingly. The
groups are not, however, clear-cut. Cellular density is an
important factor to consider in the breeding of potatoes for

SOLANACE 579

table use, or for the industries. For table use, only those
tubers should be selected which have small cells (high
density), and for starch factories only those with large cells
(low density). Even with the same amount of starch in two
varieties, it is found that the large-celled one is the more
valuable to the starch industry, due to the fact that in the
small-celled varieties a larger number of the cells remain
intact and do not give up their starch in the starch-removing
process, while with the large-celled varieties fewer starch
cells escape being broken up. In France, it was found that
rich, compact (heavy) soils produced tubers with a low
cellular density, while the lighter 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:

i No. of | No. of

Source | analyses varieties | Protein | Starch Quality
Connell caein on aaa ee | 4 1.899 | 17.356 | Very good.
IMIAITIO! 2 tsysealecsrsy eset ve teneeeecte 16 4 2.170 | 18.037 | Very good.
U.S. all sources............, 136 1 ..... 2.200 | 18.400
France: |
Coudon and Boussard..... i SE 2.676 | 11.798 | Very good.
Coudon and Boussard..... 8 © 8 2.411 | 13.218 | Good.
Coudon and Boussard..... 7 a 2.365 | 14.118 | Passable.
Coudon and Boussard..... | 12 12 2.090 | 16.047 | Poor.

Water and nitrogen increase from the outer to the inner
zones, while the starch content decreases.

The following table showing composition of the potato is
from East:

580 BOTANY OF CROP PLANTS

' Dry Total N, | Total N,

Variety , Zone matter, ' fresh basis, dry basis,

per cent. per cent. per cent.
{ Rural. . .. ... Cortical . 20.95 0.46 2.20
| New Votker. ... Outer Med./ = 18.46 0.47 2.56
| Now@eers, queen. Inner Med. . 14.04 0.45 3223
Carman No. 3.... Cortical 22.20 0.49 ' 2 2"
Outer Med. — 19.41 0.51 2.63
‘Inner Med. 14.92 0.52 3-49

This table shows that the dry matter decreases from the
outside to the inside of the tuber. The nitrogen content
shows an increase, on dry basis, from the outside to the
center, although on a fresh basis there seems to be no regu-
larity of percentage, probably due to variability in water
content. The inner cells of the cortex contain a much larger
amount of starch than those of the external medulla, which
in turn contain considerably more than the cells of the inter-
nal medulla. The outer cells of the cortex which are removed
with the skin (in peeling) are comparatively low in starch.

Starch and Sugar.—-Potato starch grains are egg-shaped
or nearly spherical with eccentric markings, and with the
hilum near the small end. Some varieties of potatoes are
abundantly supplied with large starch grains with infre-
quent small ones, while in other varieties the reverse is the
case. No correlation has been found between the size of
the starch grains and the size of the tuber or its total starch
content. In general, the early varieties contain large starch
grains while the late varieties contain a larger proportion of
small grains. Starch-grain formation is very slow. At first,
many small grains are found, most of which later increase in
size. This increase in size begins much sooner in early
varieties than in late varieties.

SOLANACEE 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,
mealiness is the most important consideration. Mealiness
depends quite largely upon the amount of starch in the cells.
When boiled in water, the starch grains expand and coalesce.
If there is 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 this country potatoes must contain about 17
per cent. or more of starch. As a result of experimentation
with 15 American varieties, East says: ‘It is quite evident
then that potatoes having as far as possible a homogeneous
flesh and containing as large an amount as possible of cor-
tical and outer medullary layers in proportion to inner med-
ullary layer, should be of the finest quality.”

Degree of Maturity and Quality.—Analyses in the United
States have shown that the ‘‘greater part of the total nitro-
gen is developed early in the growth of. the tuber, while the
starch is stored up later.”” It was also found that ‘the starch
grains of immature tubers are small in size and few in
number.” Tubers increase in desirability with maturity.

Degeneracy of the Potato.— The “running out”’ of potatoes
is a common observation. New varieties are put on the
market, are very productive for a varying number of years,
then they usually begin to ‘‘run out”’ or degenerate.

In Colorado, varieties in the mountain districts do not
tend to run out, or only very slowly, the tendency apparently
being easily overcome by seed selection, while in the Greeley
district, on the plains, at an altitude of 4,600 feet, the sexual
tendencies and consequent degeneracy seem to overcome
other influences, such as selection. At Svalof (Sweden) the
opinion is held that in a variety of potatoes ‘there is no
period of old age.” On the other hand, degeneracy is be-

SOLANACEE 583

lieved to be the result of ‘‘factors which hinder the normal
development of the plants and tubers or invite disease.”
Stewart recently describes forms of degeneration known
as leaf-roll, curly-dwarf, mosaic and spindling-sprout. He
found that the progeny of plants with normal foliage and
high yield may very suddenly degenerate into dwarfish plants
affected with the above-mentioned diseases. The leaf-roll,
curly-dwarf and mosaic troubles are passed from generation to
generation by means of the tubers. The nature of spindling-
sprout is not this well known. The observations are
significant in that they show that seed selection may not
always insure against ‘‘running out.’’ It is claimed by the
‘Svalof investigators that more vigorous seed tubers are pro-
duced in cool, moist conditions than in hot,dry regions. This
view is also held by Fitch who worked in Colorado. The
cause of this increased vigor is another question. It may be
due to a well-developed vascular system in the tuber or an
abundance of diastase at the sprouting season. Investi-
gators express the view that ‘‘where suitable sorts are used,
and where suitable tubers of these sorts are utilized for seed-
ing purposes each year, the standard of a variety may be
maintained indefinitely under all favorable conditions of soil
and climate.” Hence it seems that the inherent tendency
to degenerate is perhaps no stronger in potatoes than in other
crops, but that they are more widely and strongly influenced
by environmental conditions than are most crops. It is re-
ported that at Svalof the variety Dala, introduced about 150
years ago in the province of Delarne, is still one of the best
sorts grown there.

Environmental Relations.—The potato is a native of the
high, cool regions of Mexico and South America. In the
United States it thrives best in a cool, moist climate as is
evidenced by the fact that the five leading potato States

584 BOTANY OF CROP PLANTS

touch the Canadian border. It is well adapted to elevation
up to 8,000 feet in the Central Rocky Mountains. Smith has
shown that the potato makes its best development in those
sections of the country where the mean annual temperature
is between 40° and 50°F., and where the mean for July is not
over 70°F.

The plant is grown on both heavy and light soils, but the
latter are preferred; upon these, the plant is less subject to

EUROPEAN

RUSSIA 22.2%

Fic. 238.—Percentage of the world’s supply of potatoes produced in the
different countries in 1914.

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: (1) 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

SOLANACEE 585

by rasping machines. The pulp is passed through sieves,
which separate the fiber from the liquor containing starch.
The liquor is allowed to stand, and during this time white
starch settles in layers at the bottom of the receptacle. The
starch is drawn off, purified by allowing it to run over tables,
similar to those used in the purification of corn starch (page
184), and finally dried. ‘‘Culls” are profitably employed in
starch manufacture.

Alcohol.—In Germany, the potato is used extensively for
alcohol manufacture. In this country, it is too expensive
for this purpose. The process of converting the starch to
alcohol is very similar to that used in the manufacture of
alcohol from corn starch.

Production of Potatoes.—The world’s output of potatoes
in 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
purplish 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.

Fic. 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:

1. 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

SOLANACEE 587

Improved, Giant Round Purple) and others with white or
striped fruit (White Chinese, Long White, White Egg).

2. S. melongena var. serpentinum (Snake Eggplant).—The
plants are medium to tall, the leaves large, and the fruit long
and slender.

3. S. melongena var. depressum (Dwarf Purple Eggplant). —
The plants are small, weak, and spreading, the leaves small,
the flowers small, and the fruit small to medium, pear-
shaped, and purple (Early Dwarf Purple).

LYCOPERSICUM (Tomato)

Habit of Growth, and Stems.—-The tomatoes are annual
or short-lived perennial, coarse, branching or feebly climbing
herbs, that vary in size and form with the species, climate,
and methods of culture. The upright growing tomatoes
(L. 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 calyz is five- to six-parted; the segments are
linear or lanceolate, persistent, and increase in size with the
development of the fruit. The corolla is rotate or wheel-
shaped, cleft into usually five, sometimes more, lobes; the
tube of the corolla is short. There are five stamens (some-
times more) attached to the corolla tube; the filaments are
very short, and the anthers open by a longitudinal slit on
the inner side; they are elongated, connate or connivent.
There is one pistil bearing a single style and an ovary, which
is usually two-celled (more than two-celled in cultivated
tomatoes) and has a central, fleshy placenta.

Pollination, Fertilization, and Development of the Fruit.—
In the maturing of the flower, the style elongates and pushes
the receptive stigma through the tube formed by the anthers.
In some instances, this elongation occurs prior to the dehisc-
ing of the anthers, hence eliminating the possibility of self-
pollination. Sometimes the anthers shed pollen at the time
the stigma is pushed upward, and in the growth of the stigma
it rubs against the dehiscing surface of the anthers. Stigmas
remain receptive for several days. However, it is known
that greenhouse tomatoes do not set fruit well unless arti-
ficially pollinated, as is commonly done by jarring the plants
at the time of anther dehiscence. Natural cross-pollination
seldom occurs.

SOLANACEZ 589

Extensive experiments made by Fletcher and Gregg with
greenhouse or forced tomatoes showed that self-fertilized
blossoms set fruit as well as cross-fertilized ones. Further-
more, there was practically no difference in the appearance
or weight of the fruit, and no difference in the number of cells.

Parthenocarpy.—This phenomenon is not at all uncommon
in tomatoes. By this is meant the ripening of the fruit
without the fertilization of the ovules. Such fruits, of
course, possess no germinative seeds.

Abnormal Tomatoes—Munson has found, in crossing
tomatoes, that the amount of pollen placed on the stigmas
affects the size of the fruit. Two stigmas-in the same flower
cluster were given different amounts of pollen: one abun-
dant pollen, the other 10 to 20 grains. With plenty of
pollen, normal fruit resulted, while with scanty pollen, small
and deformed fruit resulted. In the first case, there was
abundant seed, while in the latter, only a few seeds. One-
sided tomatoes result when pollen falls upon one side of the
stigma only. It is undoubtedly commonly true that small
and irregular tomatoes are caused by an insufficient supply
of pollen.

The Mature Fruit.—The fruit is a true berry (Fig. 240).
The wild form of our common garden tomato (S. esculentum)
has a two-celled fruit with a rather dry placenta. The cells
are definite in both number and shape. Cultivated forms
of the common garden tomato have a number of cells in the
fruit; they are indefinite in both number and shape, and the
placenta is exceedingly fleshy. The fewest celled fruits are
considered nearest the original type. The pear and cherry
tomatoes both have two-celled fruit. The calyx is persist-
ent, adhering to the base of the fruit. The fruit varies in -
shape, color, and smoothness of surface. The seeds are
numerous and small.

5990 BOTANY OF CROP PLANTS

Geographical.—All the species in this genus are natives of South America.
Dunal, in DeCandolle’s Prodromus, gives ro species of Lycopersicum,; this
number is reduced, however, by some writers. Tomatoes are warm season
‘‘vegetables” that require transplanting in central and northern latitudes.

Important Species and Varieties.—There is a difference of
opinion whether to consider certain forms of tomatoes
species or only varieties. For example, Bailey recognized

Fic. 240.—Cross-section of mature fruit of cultivated tomato (Lycopersicon
esculentum).

but two cultivated species of Lycopersicum: L. esculentum,
the common tomato, and L. pimpinellifolium, the currant
tomato. L. esculentum is, according to Bailey, divided into
the following varieties:

1. L. esculentum var. vulgare, garden tomato.

2. L. esculentum var. cerasiforme, cherry tomato.

3. L. esculentum var. pyriforme, pear or plum tomato.

4. L. esculentum var. validum, upright tomato.

5. L. esculentum var. grandifolium, large leaf tomato.

L. pimpinellifolium is not subdivided. On the other hand,
Tracy regards as distinct species: L. pimpinellifolium, L.

SOLANACEZ 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, U pright tomato.
Plants taller, the branches weaker and more spreading.
Leaves very large, about two pairs of almost entire-margined leaflets,
Large-leaf tomato.
Leaves of medium size, numerous 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 }4 to 34 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 (Physalis 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 small berry. The fruit is esteemed by some for preserving,
or making pies, or for eating raw.

The tree tomato (Cyphomandra betacea), a tropical plant, has a fruit similar
in taste, at least, to that of the common tomato. This plant also belongs to
the Solanacez, but may be distinguished from Lyco persicum by its woody
habit of growth.

History.—The tomato is still found in the wild state in
South America. The Spanish explorers carried the fruit to
southern Europe where it was used as a food long before it was
eaten by the people of northern Europe. -It was early known
in England and America as the “‘Love Apple.”’ A prejudice
against the tomato existed for a long time, no doubt due to
its alliance with the nightshades. Now, however, it is
a favored article of diet, and from 500,000 to 600,000 acres
are devoted to its growth annually in the United States and
there are as many as 175 different varieties offered by seeds-
men.

Uses.—Tomatoes are commonly used, fresh or canned, as
a table vegetable. Large quantities are made into catsup.
Such varieties as Red Plum, Yellow Plum, Red Pear-shaped,
Red Cherry, and Burbank’s Preserving are used quite ex-
tensively for pickling.

CAPSICUM ANNUUM (Peppers)

Description.—This species is either an annual or biennial
herb, 2 to 5 feet tall, and sometimes partly woody at the base.
In temperate regions, the plant is cultivated as an annual,
while in warmer climates it is often biennial. The Jeaves are

SOLANACEAE 593

ovate and entire. The flowers (Fig. 241) are solitary, or
in twos or threes. The calyx is five-lobed, truncate, obcon-

ical, cup-shaped or funnel-

form. The corolla is white,
\ = £-corolla lobes
J) ts Ay stamen

rotate, usually five-lobed,

There are five stamens, some-
times six or seven, attached
near the base of the corolla;
the bluish anthers dehisce
longitudinally. The ovary is
usually two-celled, rarely
three-celled, and bears a

with the lobes’ valvate.
y
Hf —calyx lobe
Vi

-2-celled

thread-like style, and numer-
ous ovules. The fruit (Fig.

Fic. 241.—Median longitudinal
section of pepper flower (Capsicum
annuum). X 2.

242) is a berry, red or green .
in color, and short cylindrical or globular in shape. There
are many seeds in each fruit.

Fic. 242.—Cross and lengthwise sections of the fruit of pepper (Capsicum
annuum).

38

594 BOTANY OF CROP PLANTS

Geographical.—This species has never been found wild. But it is quite well
established that the entire genus Capsicum had its origin in tropical America.

Fic. 243.—Fruits of peppers (Capsicum annuum). A, Oxheart (C.
annuum cerasiforme); B, Cherry (C. annuum cerasifera); C, Celestial (C. an-
nuum abbreviatum); D, Chilli (C. annuum acuminatum); E, Long Cayenne

-(C. annuum acuminatum); F, Long Yellow (C. annuum longum); G, tabasca
(C. annuum conoides); H, Sweet Spanish (C. annuum grossum); J, Ruby
King (C. annuum grossum); J. Bell (C. annuum grossum); K, Squash (C.
annuum grossum). (After Irish.)

The temperature requirements of peppers are similar to those of eggplants
and tomatoes. Their season of growth isso long that they are unable to

SOLANACE 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 10 feet high. Its fruit does
not ripen well in northern latitudes. The fruit is red, small, and is often
called ‘‘bird pepper.”

Types.—lIrish, in his excellent monograph of the genus
Capsicum, places the numerous commercial varieties into
seven types or botanical varieties (Fig. 243). The following
key to these types is taken (verbatim) from this work.

Key To BOTANICAL VARIETIES OF CAPSICUM ANNUUM

Fruit oblong-linear.

Calyx usually embracing base of fruit.

Fruit usually less than 114 inches long; peduncles about as long or longer,
C. annuum conocides (Coral Gem, Tabasco, Cayenne, Orange-red
Cluster).

Fruit usually more than 114 inches long; peduncles shorter.

Leaves and fruit fascicled; fruit erect, C. annuum fasciculatum (Red
Cluster, Yellow Cluster).

Leaves and fruit not fascicled, C. annuum acuminatum (Chilli, Long
Cayenne, Nepal Chili).

Calyx not usually embracing base of fruit, except in the Ivory Tusk variety,
C. annuum longum (Black Nubian, Long Red, County Fair, Cardinal,
Long Yellow, Ivory Tusk).

Fruit oblate or oblong, truncated, deeply lobed, furrowed and wrinkled; flesh
mild, }4 2 to 14 inch thick, C. annuum grossum (Monstrous, Sweet Spanish,
Bell, Sweet Mountain, Golden Dawn, Ruby King, Brazilian Upright,
Golden Upright, Squash).

Fruit subconical, ovate or elliptical, slightly longer than broad, 34 to 2 inches
long; calyx not embracing base, C. annuum abbreviatum (Celestial, Etna,
Kaleidoscope, Red Wrinkled, Princess of Wales).

Fruit generally smooth, oval, spherical, cherry or heart-shaped, 3¢ to 114
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 OF CROP PLANTS

Cherry) the pungency is in the pericarp as well as in the pla-
centa and seed. In larger varieties (Squash, Bell, Sweet
Mountain), the pungent taste is located for the most part
about the seeds, while the fleshy pericarp is ‘‘ mild.”

Uses.—Medicinally, the red pepper is used in a great
variety of ways. Probably its most important use is as a
condiment, Cayenne Pepper being the common form. This
is made by grinding up the entire fruit to a fine powder.
Pepper sauce is the unground fruit preserved in brine or
strong vinegar. Tabasca Pepper and Tabasca Catsup are
examples of this. Chilli con carne is a mixture of small,
finely ground peppers and meat. Peppers are commonly
used in tamalas, also in pickles and salads, while bell-shaped
and squash varieties are used as mangoes. Some varieties,
such as Little Gem and Prince of Wales, are grown for orna-
mental purposes.

NICOTIANA (Tobacco)

Habit.— Most representatives of this genus are tall, stout
herbs. Several (as N. glauca and 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 J/eaves are simple, alternate, mostly large,
entire or wavy along the margin, petioled (in N. glauca), or
sessile and decurrent.

Inflorescence and Flowers.—The inflorescence is a terminal
raceme or panicle. The flowers are large and vary in color:
white, yellowish, yellowish-white, greenish, purplish, or rose.
The calyx is synsepalous, five-cleft, and usually persists in
the fruit. The corolla is salverform or funnelform, five-
lobed, and the tube is longer than the limb. There are five

SOLANACEE 597

stamens attached to the corolla tube; the filaments are slen-
der, and the anthers split lengthwise. The two-celled ovary
bears a single, slender style, and a capitate stigma.

Fruit.—The fruit is a two-celled capsule bearing numerous
very small seeds; it splits into two or four valves at maturity.

Geographical Distribution and Economic Importance.—
The genus includes about so species, mostly of the American
tropics. A number of species are grown for ornamental pur-
poses. J. 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 sfems which are hairy and sticky. In tobacco culture
it is customary to “top” the plants, that is, remove the
flower stalks, so that a considerable portion of the food supply
which would normally go to flower and fruit production may
be directed to leaf growth. Topping stimulates the produc-
tion of ‘suckers’? (new shoots). They must be removed
before reaching any great size, as the quality of the leaves is
damaged by their growth. The ‘“one-sucker”’ type of
tobacco is one that throws out one or only a few suckers.

Leaves.—There is great variation in the shape, color, tex-
ture, and number of leaves. In cigar-wrapper tobaccos, the
leaves are thin, fine in texture, and small-veined. The
leaves of plug and pipe tobaccos are usually coarser, thicker,
and tougher. ‘The leaves are sessile, decurrent, and either
narrow or broad, most commonly lanceolate or ovate, and
pointed. The number of leaves on a plant, which is, of
course, important commercially, is different in the various
types and also varies considerably from plant to plant in the

598 BOTANY OF CROP PLANTS

same type. In the Sumatra cigar-wrapper tobacco the
leaves range from 16 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 papille vary in size from about 1 millimeter to
microscopic dimensions. Each grain body consists of from
one to several leaf cells filled with crystalline substance.
The grain is composed chiefly of calcium, with some potas-
sium and magnesium, in combination with citric and malic
acids. Grain of tobacco is developed during the process of
curing and fermentation. It is a character that the buyer
takes into consideration when he selects tobacco.

Inflorescence and Flowers.—The inflorescence is a terminal
panicle. The flowers (Fig. 244) are about 2 inches long, and
pink, yellow, purple or white. The tubular or bell-shaped
calyx is four- to five-cleft. The tube of the corolla is swollen,
its lobes spreading and pointed. |

Pollination and Fertilization—Tobacco flowers bear nec-
taries and are visited by insects. Hence, cross-pollination
is probably somewhat frequent. Moreover, observations
and experiments show that the flowers are self-fertile—that
they will produce viable seed when close-fertilized. The
earlier blossoms of an inflorescence are more commonly
close-fertilized than are the later ones of the same inflores-

SOLANACEE 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.

Fic. 244.—Tobacco (Nicotiana tabacum). A, flower; B, pistil; C, corolla
cut open and spread out flat; D, cross-section of young fruit; E, lengthwise
section of young fruit. (After Strasburger.)

Fruit.—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.

600 BOTANY OF CROP PLANTS

Closely Related Species.—There are a number of species of Nicotiana which
resemble N. tabacum somewhat, and there are several species belonging to
other genera besides Nicotiana that go by the name “tobacco.”

N. rustica is a “wild tobacco” that was cultivated by the Indians. It isa
tall annual with petioled leaves. WN. guadrivalvis is another plant cultivated
by the Indians for tobacco. It is native to the region extending from Texas
to California and Oregon. WN. persica yields Persian tobacco. ‘Australian
tobacco”’ is the leaf of Dudoisia hopwoddii, a species of Solanacee. ‘‘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,
Campanulacee. Arnica alpina, a composite, is sometimes known as ‘‘ moun-
tain tobacco.” The most popular ornamental Nicotiana is N. alata. In it
the flowers are white, open at night and closed in the daytime.

Types and Varieties——There are two general types of
tobacco grown in this country:

1. Cigar type, the leaves of which are made into cigar
wrappers, binders and fillers. The leaves are thin and of
fine texture. Common varieties are Sumatra, Connecticut
Havana, Connecticut Broadleaf, Cuban, Zimmer Spanish,
and Little Dutch.

2. Export and manufacturing type, the leaves of which are
used to make smoking tobacco, chewing tobacco, cigarettes,
and 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

SOLANACEE 601

removes large quantities of nitrogen, potash, and phosphoric
acid from the soil. Consequently, the plant is rich in these
valuable plant nutrients. In fact the leaves and stalks
make excellent fertilizers, and are so used in tobacco sections.

Curing Tobacco.-—This process consists in removing the
moisture in the leaves and stems in such a manner as to
produce a uniform color and texture in the leaves. Artificial
heat was first employed in the curing of tobaccos in 1812.
Wood fires were used up to the year 1828, about which time,
flues, and charcoal fires came into use. Flue-curing entirely
replaced charcoal fires in 1865. Flue-curing produces a
bright yellow leaf. The green tint is obtained by harvesting
the leaf before it is fully ripe. The dark export tobaccos are
cured with open hard-wood fires. Light tobaccos may be
air-cured, and such are used for pipe smoking, and cigarettes.
White Burley tobacco, so highly prized for twist and plug
chewing tobaccos, is usually air-cured. The yellow and
mahogany tobaccos are cured by flues. The process takes
about four days. The broad leaf and Havana seed leaf
varieties of the Connecticut Valley are air-cured. They are
domestic cigar tobaccos. Curing is often carried on in
specially constructed barns with horizontal ventilators. It
usually takes about two months to air-cure tobacco, and
less time if artificial heat is used. After the leaves have been
left hanging for a long time, they are packed closely in boxes,
where they are left undisturbed for several months. When
warm weather sets in, a process of fermentation is set up in
the cases, during which process certain important changes
take place. Fermentation may be: brought about after a
shorter period of drying than is used in the preceding
method, by placing the leaves in piles in a warm, moist at-
mosphere. When the temperature reaches 125° to 1 30°F.
the piles are opened and heaped up again. The piles are

602 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 1 penny, and where it
was used for the “payment of all debts, including customs,
dues, salaries of State officers and ministers of the gospel.”
In 1777 the tax levy for the county and city of Baltimore was
172 pounds of tobacco per poll. ;
Virginia and Maryland were long the only tobacco-pro-
ducing States. The industry has now spread to other States,
and the production in 1915 is shown in the following table:

Tospacco: ACREAGE, PRoDUCTION, AND ToTAL Farm VALUE,
BY STATES, 1915

‘ . Farm value
State Acres Pounds ' Dec. 1,

dollars
Kentuckyiessccasccwca ve « | 440,000 356,400,000 | 23,799,000
North Carolina............} 320,000 198,400,000 22,221,000
Virginia. 4 sos yseeeeeeg 33 192,500 i 144,375,000 i 13,571,000
O12 3 2on8cesd ste tla: | 93,700 84,330,000 7;590,000
TENNESSEE sated scm Gorden ns : 92,900 69,675,000 4,990,000
Pennsylvania............. a 31,400. 42,390,000 — — 3,900,000
South Carolina............ I 65,000 | 37,700,000 | 2,639,000
Wisconsin................ 7 41,000 j 36,900,000 2,214,000
Connecticut. sii AERA REESE | 22,200 29,907,000 3,095,000
Maryland................-! 22,000 | 16,280,000 1,384,000
All other States.......... 47,700 ' 44,030,000 12,638,000

96,041,000

United States..............; 1,368,400 1,060,387,000

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604 BOTANY OF CROP PLANTS

The United States leads all other countries in the produc-
tion of tobacco. In 1914, Japan ranked second to the

United States, but its output was only about ro per cent. of
that in this country.

References

APPLEMAN, C. O.: Physiological Behavior of Enzymes and Carbohydrate
Transformations in After-ripening of the Potato Tuber. Bot. Gaz., 52:
306-315, IQII.

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, I90I.

BERTHAULT, PreRRE: 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, ro11.

Fircu, C. L.: Productiveness and Degeneracy of the Irish Potato. Colo.
Agr. Exp. Sta. Bull. 176: 1-16, 1910.

Indentification of Potato Varieties. Ia. Agr. Ext. Dept. Bull. 20: 1-32,
194.

FLETCHER, S. W., and Grec«, 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.

GaBLeE, C. H.: The Wild Tomato. Jour. Hered., 6: 242, 1915.

GitmorE, JoHN W.: Quality in Potatoes. Cornell Agr. Exp. Sta. Bull. 230:
503-525, 1905.

GoopsPEED, T. H.: Parthenogenesis, Parthenocarpy and Phenospermy in
Nicotiana. Univ. Calif. Pub. Bot., 5: 249-272, 1915.

HatsteEab, B. B.: Notes upon Stamens of Solanacee. Bot. Gaz., 15: 103-
106, 1890.

HEcKEL, E.: Sur V’origine de la pomme de terre cultivee et sur les mutations
gemmaires culturales des Solanum tuberiferes sauvages. Ann. Fac. Sc.
Marseille, 1907, 82 pp. ‘

Irtsu, H. C.: A Revision of the Genus Capsicum with Especial Reference to
Garden Varieties. oth Ann. Rep. Mo. Bot. Gard., 53-110, 1898.

Jonrs, DonaLp F.: Natural Cross-pollination in the Tomato. Science, n. s.,
43: 509-510, 1910.

Kriemt, F.: Uber den Bau und die Entwickelung der Solanacecnfruchte.
Berlin, 1907.

SOLANACEZ 605

Macrov, H.: Symbiosis and Tuberization in Potato. Compt. Rend. Acad.
Sci. (Paris), 158: 50-53, 1914.
Mipp_eton, R. Morton: Solanum Tuberosum L., and Its Allies. Jour.
Bot., 47: 228, 1909.
Reep, T.: The Anatomy of Some Tubers. Ann. Bot., 24: 537-548, 1910
(Potato and Jerusalem artichoke).
ReENpDLE, A. B.: Production of Tubers within the Potato. Jour. Bot., 31:
193-195, 1893.
Ricpway, CHar es 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.
Wi1tmAck, 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
CUCURBITACEZ (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 lobata) and
the star cucumber (Sicyos angulatus) are sometimes planted
as ornamental vines. The squirting cucumber (Ecballium
elaterium) is a fleshy herb containing a cathartic and poison-
ous principle, elaterin, the main ingredient of elaterium.

Habit.—The members of this family are commonly known
as “‘cucurbits.”” The majority of them are annual, climbing
or trailing herbs, with tendrils, but often reaching a large
size.

Stems and Leaves.—The stems are hollow and usually
covered with stiff hairs. The leaves are large, alternate,
petioled, heart-shaped, palmately lobed or dissected. The
tendrils arise as a rule in the axils of leaves. The same ten-
dril may be dextrorse and sinistrorse at different points along
its axis and may be simple or forked.

Flowers.—The flowers (Figs. 246 and 247) are axillary,
either solitary, paniculate, or rarely racemose or subumbel-
late. They are moncecious or dicecious, 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

CUCURBITACE 607

late, and usually has five imbricated lobes. The corolla is five-
lobed, usually sympetalous, sometimes parted to the base, in-
serted on the limb of the calyx, and rotate or campanulate.
The stamens (Fig. 247) are five in number, but they often grow

Fic. 246.—Field pumpkin (Cucurbita pepo). A, staminate flower; B, pistil-
late flower.

together so that there are apparently three. In case there:
are three stamens, two of them are broader than the third;
the two broad stamens have two-celled anthers, the other has
a one-celled anther, thus making in all five anther cells to the
andreecium. The filaments are short, often united, and

608 BOTANY OF CROP PLANTS

tipped by the worm-like pollen sacs. The ovary (Fig. 248) is

inferior, one- to three-celled, and usually has numerous seeds

in each cell or locule; the style is terminal, simple or lobed.
Fruit.—The fruit is a pepo, usually indeliscent, or in some

Fic. 247.—Field pumpkin (Cucurbita pepo). 4A, pistillate flower; B, stami-
nate flower; both with perianth removed.

cases (Micrampelis, Cyclanthera) dehiscent at the apex or
bursting irregularly. In many instances (watermelon,
pumpkin, squash), the fruit is of enormous size. The outer
part of the fruit is receptacle which has become attached to
the exocarp. The flesh of the fruit is chiefly mesocarp and

CUCURBITACEE 609

Fic. 249.—Germination of pumpkin (Big Tom) seeds, showing the
pegs functioning in the removal of the coats. (After Crocker, Knight and
Roberts.) 5

39

610 BOTANY OF CROP PLANTS

endocarp. Seeds are usually abundant, flat, and without
endosperm.

Germination of Cucurbit Seeds.—The cotyledons are
epigean in all the common members of the Cucurbitacez.
There are a few hypogean forms, such as Megarhize californica
and Sicyosperma gracilis. The first portion of the seedling to
appear above ground is the hypocotyl, which emerges as an
arch (Fig. 249). At the base of the hypocotyledonary arch,
there is developed a peculiar outgrowth known as the “‘ peg.”
It is a natural part of the plant, and although it varies some-
what in size in different cucurbits, it has been shown that
gravity has no direct effect in increasing peg development
or in determining its lateral placement on the hypocotyl.
The peg serves to hold the seed coat while the hypocotyl
withdraws the cotyledons from the coat. It will be noticed
(Fig. 249) that one edge of the seed coat is caught against the
peg.

Key To PRINCIPAL GENERA

Corolla rotate or campanulate, five-parted to or almost to the base.
Tendnils often two to three times branched, Citrullus (watermelon, citron).
Tendrils simple, Cucumis (muskmelon, cantaloupe, cucumber).

Corolla campanulate, five-lobed to or little below middle Cucurbita (gourd
pumpkin, squash). :

CUCURBITA (Squash, Pumpkin, Gourd)

Stems, Leaves, Flowers.—Members of this genus are
annual, prostrate bushy or trailing vines with rough stems
which have a tendency to root at thenodes. The tendency is
particularly marked in the long-running varieties of squashes
(Turban, Marblehead, Canada Crookneck, Field Pumpkin).
The tendrils are branched. The /eaves are usually cordate
at the base, lobed (C. pepo), or not lobed (C. maxima).
The flowers are always solitary in the axils of the leaves,
yellow, and monececious. In squashes with a bushy habit

CUCURBITACEE 611

(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 (asin 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 placentz, style short and thick, and stigmas three to
five, each two-lobed and papillose. There are always many
more staminate flowers produced than pistillate.

Pollination and Fertilization The squashes and pump-
kins are usually insect-pollinated. It has been shown that
the varieties of C pepo, including the common Crookneck,
Scallop, and Pineapple squashes, and the common field
pumpkin, will readily cross with one another. However, the
above will not cross with varieties of C. maxima, including
Hubbard, Marblehead, Turbans, and Mammoth Chili and
Valparaiso pumpkins. These latter will cross with one
another. Varieties of C. moschata will not cross with either
of the above species. Cucurbita species do not cross with
melons and cucumbers. Squashes and pumpkins ordinarily
do not reach any considerable size unless the ovules are
fertilized.

Mature Fruit—The mature fruit is a pepo. In the

612 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.

B

Fic. 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),

Fic. 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.).

CUCURBITACE 613
CUCURBITA PEPO

Description.—This is an annual species, with long, running
stems; in the so-called “bush-pumpkins,”’ which include the
scallops (patty-pans or cymblings) and summer or crookneck
squashes, the plants are more compact. The Jeaves are
three- to five-lobed. The calyx lobes are narrow. The
peduncle is not enlarged next to the fruit. The fruit varies
much in size and shape.

Origin.—There is a question as to the origin of the pump-
kin. It is considered by some to be of American origin, as
it was cultivated by the Indians at the time America was
discovered. However, it is claimed by others that its original
home is southern Asia.

Types and Varieties.— Cucurbita pepo includes the follow-

ing groups:

Plants with long, running stems, True field pumpkins (Connecticut field and
Mammoth are common varieties).

Some of the vegetable marrows have long, running stems, while others
have a bushy habit. As a group they are relatively unimportant.
Plants bushy, Summer squashes, crooknecks. In these the neck is decidedly

crooked and narrow, the distal end is swollen but terminating in a point,
the skin is orange-colored and covered with many round excrescences.
Scallop or patty-pan varieties. These are also known as custard marrows,
and in the South as cymblings. The leaves are large, entire, and very
slightly five-lobed; the fruit is much broader than long, the edge coarsely
scalloped; the flesh is solid and floury; the skin is smooth and of various
colors. The pineapple summer squashes are oblong-conical varieties.
Plants with slender, running stems; leaves lobed; fruit small, hard, not edible,
of various shapes, Gourds (in part) (C. pepo var. ovifera).

Not all ‘‘gourds” belong to the species Cucurbita pepo.
In addition to this species, they are also referred to Lagenaria
vulgaris, Luffa, Cucumis dipsaceus, Cucumis. anguria, and
Benincasa certfera.

614 BOTANY OF CROP 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, z.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 most popular
squashes in the Northern States. They are broadly pear-
shaped, or olive-shaped with very thick, hard, dark green
skin and dark yellow, floury flesh. There are varieties of
the Hubbard (Red or Golden Hubbard) with orange-red skin.

3. Marblehead Squashes—These have a gray skin. Other-
wise they resemble the Hubbard.squashes.

4. Marrow Squashes——There are a number of varieties of
these, only a few of which are very well known. Most of
them have a smooth skin and a very floury flesh. The
Boston Marrow, a variety with orange-colored skin and flesh,
is the best known in the United States.

CUCURBITACEE 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 1 to 2 feet and a weight of 100 to 200 pounds.
The Mammoth pumpkins are strongly flattened at the ends,
while the mammoth squashes are longer than broad, and
oblong or narrowly oval in shape.

CUCURBITA MOSCHATA

Description.—This is an annual with long, running, hairy
(never spiny) stems which readily root at the nodes. The
leaves are lobed, dark green and with whitish blotches here
and there. It is said that these whitish areas are due to a
thin layer of air beneath the epidermis. The calyx is deeply
lobed. The corolla widens upward. The peduncle is
angular, deeply ridged, and swollen where it joins the fruit.
The flesh of the fruit usually has a musky flavor.

The species is said to have originated in Eastern Asia.

Types.—The principal types belonging to this species are:

1. Canada Crookneck or Winter Gourd.—The plants are
small; the fruit is also rather small, smooth and crook-
necked.

2. Cushaw.—This is the ‘‘pie pumpkin” or squash of the
South and Southwest. It is a crook-necked type of squash,
the skin of which may be white, yellow, or striped.

CUCUMIS (Muskmelon, Cantaloupe, Cucumber)

Stems, Leaves, Flowers.—All of our common species are
hispid or rough, trailing, annual herbs. The tendrils are
simple. The /Jeaves are simple, palmately three- to five-lobed
or dissected. The flowers are moncecious. Rane finds that
some varieties of muskmelons possess perfect flowers. For

616 BOTANY OF CROP PLANTS

example, out of 95 varieties examined, 85 had perfect
flowers, and only 11 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

Fic. 252.—Leaves of A, cucumber (Cucumis sativus) and B. muskmelon
(Cucumis melo). x.

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 placente; 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.— Griffin gives data with reference to pollina-
tion and fruiting of the cantaloupe. He kept’an account of

CUCURBITACEE ; 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
PUN 6629 52. cerca amcierarn en aisne sawn caoupiteasd sack 203 I
JUNE 20 ertexe porate maweoes 338 Ir
JG Bice sag egu tam aabengie s 474 28
Dae Gerson y were ee ote 755 95
a Ot es sae aah etree an 660 87
JA Bie we dtidun ch Redade ees aaa 645 31
TROUA i sicleecetccusttl \utnnes. ansicass areiesoak 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
earlier than the pistillate ones. Pollination is carried on by
insects. Ordinarily, lack of fertilization causes a premature
dropping of the fruit, and incomplete fertilization results in
misshapen fruit.

Geographical.—There are close to 30 species of Cucumis, most of them be-
longing to tropical Asia, Africa, and the East Indies.

Key To PrincrpaL 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 1 to 132 inches long, Cucumis anguria (prickly
cucumber, West Indian gherkin, Jerusalem cucumber, gooseberry gourd),

618 BOTANY OF CROP PLANTS a

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 fertilized by each other. The principal
ones are as follows:

1. Netted Melons (Cucumis melo var. reticulatus) —To this
group belong the common muskmelons. These usually have
a netted skin, sometimes almost smooth. All of them are
shallow ribbed melons, the flesh of which may be green- or
salmon-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

CUCURBITACE 619

twisted, furrowed, and thickest at the distal end. It often
reaches a length of 3 feet, and a diameter of 1 to 3 inches.

Fic. 253.—1 to 6, stages in the development of the cucumber fruit; the
flower is unopen in 1 and 2, in 3 it is fully open, in 4 and 5 it is withering, and
in 6 the perianth, stamens and styles have fallen from the enlarged ovary. 7,
staminate flower of cucumber.

5. Winter Melons (Cucumis melo var. inodorus).—Little
known in United States.

620 BOTANY OF CROP PLANTS

6. Cucumber Melon (Cucumis melo var. acidulus)—O{ no
economic importance.

7. Orange Melon, Mango Melon, Melon Apple, Vine Peach,
Garden Lemon, Vegetable Orange (Cucumis melo var. chito).—
Used in making preserves.

8. Dudaim Melon, Pomegranate Melon, acon Anne’s
Pocket Melon (Cucumis melo 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 be
crossed with the melon. Experiments have shown that this
crossing is impossible. The fruit is oblong, obscurely three-
angled, tuberculate when young, but often becoming smooth
(in cultivated forms) at maturity.

Geographical.—Cucumbers have been in cultivation for 3,000 or 4,000
years. They were first cultivated in Asia. The species has not been found
growing wild.

Closely Related Forms.—There are a number of “cucum-
bers” which may be confused (at least in name) with the
common cucumber (Cucumis sativus). Chief of these are
the snake cucumber (Cucumis melo var. flexuosus), West
Indian gherkin (Cucumis anguria), musk cucumber (Cucumis
moschata), and star cucumber (Sicyos angulatus). The snake
cucumber is in reality a melon. It is characterized by the
long, narrow, twisted fruit. In the West Indian gherkin the
stems are shorter and the fruit much smaller than those of
the cucumber. It is a common practice to use young cucum-
bers as gherkins. The musk cucumber is alsoa melon. The

CUCURBITACE A 621

star cucumber fruit is compressed, dry and membranous, antl
occurs in head-like clusters.

Types.—There are three principal types of cucumbers
(Cucumis sativus): (1) 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 difger 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 Lorne. 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 Jeaves are deeply sinuate-lobed. Staminate
flowers are small, numerous, and on short peduncles, while
pistillate flowers are on long stalks. The fruzt is about 114
inches long, oval, prickly, and green with whitish streaks.
The flesh is thin, and the seeds form a proportionately large
percentage of the fruit.

The species is native of the West India Islands.

The genuine gherkins of commerce are the fruit of C.
anguria. Small cucumbers (C. sativus) are often substituted
for them, however.

CITRULLUS (Watermelon, Citron, Colocynth)

Description.—Ciirullus species are coarse, trailing herbs
with branched tendrils. The Jeaves are rotund-cordate, and
three- to five-lobed. The flowers are moncecious, 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
coro.la are as described above. The ovary is ovoid with
three fleshy placente; 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.

CUCURBITACEZ 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 Jeaves are lobed. The
flowers are pale greenish-yellow. The fruit varies in shape
and has a firm fleshy rind and a tender watery pulp, which
is usually reddish in color and sometimes purplish, yellowish
or white. The skin or rind varies in thickness from 14 inch,
in such varieties as White Gem, Gray Monarch, and Hoosier
King, to 1 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 solid. The citron
is used for making sweet pickles and preserves. It is not
eaten in the raw state. The juice of the citron is added in
equal parts to that of such fruits as peaches, cherries and
others whose juices will not “jell” by themselves to make
them produce jelly. The citron has a large amount of
pectin in the cell walls. This is the substance in fruits
which causes their juice to ‘‘jell.”

624 BOTANY OF CROP PLANTS

The citron is not to be confused with the true citron (Citrus
medica) (see page 480).

Rane divides the varieties of watermelons into six
“classes:” (1) 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, and 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., Knicut, L. S., and RoBErtT E.: The Peg of the Cucurbitacee.
Bot. Gaz., 50: 321-339, 1910.
GrirFin, 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. Ia. Agr. Exp. Sta. Bull. 23: 906-917, 1894.
Rane, F. W.: Fertilization of the Muskmelon. Proc. Soc. Prom. Agr. Sci..
150-151, 1898.
II. Classification of Watermelons. N. H. Agr. Exp. Sta. Bull. 86: 95-107,
1901.

CHAPTER XL

COMPOSIT (Thistle Family)

The composite or thistle family is one of the largest of the
plant kingdom, consisting of about 10,000 species in about
760 genera; it has a wide geographical distribution.

Representatives of the family are considered to be among
the most complex of plants, and among Dicots, of the highest
evolutionary rank. They show a combination of characters
which place them high in the scale of evolution. These are:
union of petals (sympetaly), inferior ovary (epigyny), seed-
like 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

shomatic <7
Smclies =

—-corolla-~

Fic. 254.—Jerusalem artichoke (Helianthus tuberosus). A, lengthwise
section of head, 1; B, ray flower, x6; 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,
monececious or dicecious. There are two sorts of flowers in
the composite family: (1) Disk or tubular, and (2) ray or
ligulate.

Disk Flowers (Fig. 254, C).—These are perfect and regular
and make up the so-called disk of the composite “flower.”
For example, the disk of the “sunflower” is the center. The
calyx is modified, taking the form of a few or large number of
bristles, awns, scales or teeth; this modified calyx is termed
a pappus. In some instances, the pappus is entirely wanting.
It is attached to the apex of the inferior ovary. The corolla
is tubular and five-lobed. The five stamens are attached
to the corolla and alternate with its lobes; the anthers are
united into a tube. In one genus (Kuhnia), the anthers are
distinct or nearly so. The anthers are often appendaged at
the apex and sometimes caudate or sagittate at the base;
pollen grains are spherical, often rough or prickly. There
is a single pistil, an inferior one-celled and one-seeded ovary,
and a single style which is entire (in sterile flowers) or two-
cleft at the apex; the style branches are often tipped with
appendages.

Ray or Ligulate Flowers (Fig. 254, B)—These are usually
imperfect and irregular. They have a pappus and a strap-
shaped corolla with either a long or short tube.

The composite family is divided into two large groups, the
Liguliflore and Tubuliflore. 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 Liguliflore,
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 7'ubuliflore, 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 Tubiliflore, 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,
Cichorium (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 imbricated 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).

COMPOSITZ 629

LACTUCA SATIVA (Garden Lettuce)

Description.—Common garden lettuce is a tall, annual
leafy herb, with a milky juice. There is thrown up from
a short stem early in the season a cluster of leaves varying
considerably in shape, character, and color, in the different
varieties. Later in the season, a ‘‘seed stalk”’ is sent up.
Tracy found that, at Washington, D. C., the first appearance

Fic. 255.—Asparagus lettuce, var. angustana. (After Corbell.)

of the seed stalk after sowing seed, varied from 59 (in
Emperor Forcing) to 112 (in Italian Ice) days. The Jeaves
are alternate, denticulate or pinnatifid, sessile or auriculate-
clasping, sometimes spinulose-margined, the lowest ones
large, and the upper much smaller. The inflorescence is a
panicle. The flowers are yellowish or yellowish-white, the
involucre cylindric, the bracts of which are imbricated in
several series, the outer shorter. The recepéacie is flat and
naked. The corolla rays are truncate and five-toothed at

630 BOTANY OF CROP PLANTS

the end. The anthers are sagittate at the base. The style
branches are slender. The achenes are oval, oblong, or
linear, flat, three to five-ribbed on each face, narrowed above
or contracted into a narrow beak which bears a large number

at ae

Fic. 256.—Cutting or cut-leafed lettuce, var. intybacea. (After Corbett.)

of soft, capillary, white or brown pappus bristles. The
achenes vary in color: whitish, blackish, yellowish, or
brownish.

Origin, and Geographical.—It is quite generally conceded
by botanists that our garden lettuce (L. sativa) is originated
from the wild species, L. scariola. This latter species grows

COMPOSITAE 631

wild in Europe, Canary Isles, Madeira, Algeria, Abyssinia,
and Eastern Asia, and has also become naturalized in the

ie

Fic. 257.—Cos lettuce, var. romana. (After Corbett.)

United States, where it is often a troublesome weed. In
this country, L. scariola is distributed from New York to

bers a

Fic. 258.—Head lettuce, var. capitata. (After Corbett.)

Minnesota and Missouri. The close relationship between
L. sativa and L. scariola is shown by the fact that they readily
cross.

632 BOTANY OF CROP PLANTS

There are a number of native species of Lactuca in this
country. Britton and Brown mention eight species native
of the eastern and northern United States, besides the intro-
duced L. scariola. This latter species is commonly known
as the “compass plant.”

Fic. 259.—Salsify (Tragopogon porrifolius). From left to right: unopen
flower head; side view and face view of open flower head; achene with pappus at
tip of beak.

Types of Lettuce.—Four types or botanical varieties of
cultivated lettuce are recognized. These may be dis-
tinguished by the following artificial key:

Key to Types or LEtrruce.

Basal leaves narrow, distinctly lanceolate, L. sativa var. angustana (asparagus
lettuce).

COMPOSITE 633

Basal leaves broad, spatulate, oval to roundish, always rounded at the tip.
Leaves deeply cut on the edges, L. sativa var. intybaceo (cutting or cut-
leaved lettuce).
Leaves entire or but slightly toothed.
Leaves forming a rather compact roundish or flattish head; leaves never
decidedly stiff and flat, L. sativa var. capitata (head or cabbage lettuce).
Leaves forming a conical or cylindrical-shaped head; leaves straight and
stiff, L. sativa var. romana (cos lettuce).

Fic. 260.—Single flower of salsify (Tragopogon porrifolius). x 214.

Tracy classifies the American varieties of lettuce as fol-
lows: (1) butter varieties, (2) crisp varieties, and (3) cos
varieties. These three groups are further subdivided.

TRAGOPOGON PORRIFOLIUS (Salsify or “Oyster Plant”’)

Description.—Salsify is a hardy perennial plant from a
fleshy root. The roots are about 12 inches long with a
diameter of about 2 inches at the top; the skin is grayish
white. The stems are usually somewhat branched and succu-
lent. When grown from seed, a seed stalk is sent up the
second season to a height of 2 to 4 feet. The leaves are alter-
nate, entire, linear-lanceolate, clasping at the base, and glau-
cous. Heads (Fig. 259) are single at the end of rather long,
thickened peduncles, which are often hollow for several

634 BOTANY OF CROP PLANTS -

inches below the head. The heads are purple and open.
early in the morning but usually close by noon. The in-
volucre is cylindrical, the bracts nearly equal, in one series,
linear-lanceolate, and usually much longer than the rays
of the flowers. The corollas (Fig. 260) are truncate and five-

Fic. 261.—Salsify (Tragopogon porrifolius). Headin fruit; receptacle

after having shed the achenes; single achene.
toothed at the apex. The anthers are sagittate at the base.
The style branches are slender. Achenes are linear, and termi-
nated by slender beaks, the outer ones being covered with
tubercles, particularly on the ribs below. The pappus is
grown together at the base, is plumose, and has interwebbed
branches (Fig. 261).

COMPOSITA 635

Geographical, and Closely Related Species.—The species
is a native of southern Europe. It is quite widely distributed
in this country in fields and waste places, probably as an
escape from cultivation. A yellow-flowered salsify (T.
pratensis), naturalized from Europe, is also quite widely
distributed here. The Spanish salsify or Spanish oyster
plant (Scolymus hispanicus), has a root much like that of
common salsify, but the plant differs from common salsify
in the following respects: the roots are of a lighter color and
longer, the leaves prickly, and the flowers yellowish. The
black salsify (Scorzonera hispanica), also a member of the
Composite family, bears a black, fleshy, edible tap root.
It differs from common salsify in that its leaves are broader,
flowers yellow, and its involucral bracts are in many series.

Uses.—Salsify is grown for its fleshy roots which have
somewhat the flavor of oysters, hence the common name,
“oyster plant.’’ They are used both as a cooked vegetable
and as a relish.

CICHORIUM (Chicory or Succory, and Endive)

Description.—All the species of this genus are branching
herbs. The Jeaves are alternate, mostly basal, the cauline
ones small and bract-like. The heads are large, and
peduncled or in sessile clusters along the branches. The
bracts of the involucre are in two series, the outer spreading,
the inner erect. The receptacle is flat, naked, or fringed with

_small hairs. The corolla rays are truncate and five-toothed
at the apex. The achenes are five-angled or five-ribbed,
truncate, and not beaked. The pappus consists of a number
of short scales.

Geographical.—The species of Cichorium are natives of the Old World.

There are two of economic importance: Cichorium 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 1 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.

COMPOSIT & 637

ry — = We ir heads

Fic. 262.—Chicory (Chicorium intybus). A, sessile clusters of flowers in
axils of bracts, <1; B, single floral bract enlarged, x 4; C, open flower, face
view, enlarged; D, basal leaf, x 134.

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

Fic. 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.

COMPOSITZ 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 seads are solitary or in
corymbs. Tubular (disk) and ligulate (ray) flowers are both
present; the rays are yellow and the disk is also yellow (Fig.
254). The involucre is hemispheric, with lanceolate, acumi-
nate hirsute or ciliate, squarrose bracts. There are 12 to 20
rays. The receptacle is chaffy; the chaff subtends the disk
flowers. The achenes are thick, somewhat four-angled, and
pubescent. The pappus consists of two deciduous scales.

Geographical.—The Jerusalem artichoke (also called Earth Apple, Canada
Potato, Girasole and Topinambour) is native to this country and is found
from New Brunswick and Ontario to Georgia and Arkansas, west and north
to Canada. It is grown as a crop more in Europe than in America.

Closely Related Species.—The Jerusalem artichoke is
closely related to the ‘‘globe artichoke” (Cynara scolymus)
which in fact belongs to the same family, 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.

Acaulescent.—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.

Acro petal —Developing from the outside (below) toward the inside (above).

Actinomor phic—Regular, ray-shaped; said of a flower when it can be
divided into symmetrical halves by radial planes.

Acuminate.—Taper-pointed.

Acute.—Merely sharp-pointed, or ending in a point less than a right angle.

Adnate.——Grown fast to; applied to the growing together of unlike parts.

Adventitious—Out of the ordinary place, as applied to buds or roots.

Aestivation.—The arrangement of parts in the bud.

Alliaceous.—With odor and taste of onions and garlic.

Alternate (buds, flower parts, leaves, etc.). One after another singly at
the nodes.

Ament.—Scaly unisexual spike of flowers.

Amphitropous (ovules). Half-inverted and straight, with the hilum about
the middle, and micropyle terminal.

Anatropous (ovules).—Inverted, straight and with micropyle next the
hilum.

Andrecium.—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.

A petalous.—Without petals, as in buckwheat, etc.

A pical.—At the tip or apex.

A pocarpy.—Condition in which the carpels are separate.

A popetaly.—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.
aa 6 AI

°

642 BOTANY OF CROP PLANTS

Awned—Furnished with an awn or beard.
Axillary (buds, etc.).—In the axil.

Basal.—Belonging to or attached to the base.

Berry.—A fleshy fruit, with mesocarp and endocarp fleshy throughout,
and seeds imbedded therein, as grape, currant, etc.

Biennial.—Of two years’ duration; the first year from seed, the second year
flowering and fruiting, then dying; as in sugar beet, carrot, etc.

Bipinnate (leaf)—Twice pinnate.
* Blade.—Expanded portion of a leaf.

Bloom.—The whitish, powdery, and waxy secretion of epidermal cells.

Bract.—A reduced scale-like leaf, above the regular foliage leaves.

Bracteclate-—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.

Cam panulate—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.

Ca prification.—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.

Cauliflorus —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.

Cladophyli.—A leaf-like branch.

Claw.—The narrow or stalk-like base of some petals.

Cleft-—Cut about halfway to midrib or median line.

Coles ptile.—Leaf sheath in grasses.

Colecrhiza.—A sheath about the root.

Commissure—The contiguous surfaces of two carpels, as in the fruit of
Umbelliferz.

GLOSSARY 643

Conduplicate-—Folded lengthwise.

Connivent.—Overlapping or brought close together.

Conver gent-—Margins touching.

Convolute—Rolled lengthwise.

Cordate.—Heart-shaped.

Corneus.—Horny.

Corm.—The swollen, fleshy, and solid base of a stem.

Cortex.—Bark region, {rom 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.

Cuticle——A thin covering of a waxy substance called cutin on the outer
wall of epidermal cells.

Cyme.—A determinate type of inflorescence, in which the first flowers to
open are those toward the inside.

Cymose.—Cyme-like, or bearing cymes.

Decompound.—Several times compound or divided, as in leaves of carrot.

Decumbent.—More or less prostrate, but with the tips ascending.

Decurrent (leaf) Extending down the stem below the point of insertion.

Dehiscence.—The opening of a fruit or anther.

Dehiscent.—Splitting open.

Dentate-—Sharp-toothed; teeth directed forward.

Denticulate.—Diminutive of dentate; furnished with very small sharp teeth.

Diadel phous (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 dicecious and
moneecious plants.

Digitate——The spreading of segments like the fingers from palm of hand.

Dilated. — Expanded.

Dimor phism.—The occurrence of two distinct forms, as in flowers of buck-
wheat.

Diecious—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—yYoung plant within the seed.

Endocarp.—tInner 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; applied to flowers with pistils
or to anther with pollen.

Fertilization.—A sexual process in which two dissimilar gametes fuse.

Fibrous.—Fiber-like, usually referring to root system of many small thread-
like roots.

Filament.—Thread; stalk of stamen.

Filamentous —Thread-like.

Fimbriated.—Fringed.

Foliaceous—Leaf-like in form and texture.

Follicle—A dry, dehiscent fruit with one carpel which splits along the
ventral suture.

Funnelform.—Funnel-shaped.

Geitonogamy.—A method of pollination in which pollen is taken from anther
to stigma of another flower on same plant.

GLOSSARY 645

Geniculate—Bent abruptly at an angle, like the bent knee.

Glabrous.—Smooth; without hairs, scales, or bristles.

Glandular —Furnished with glands.

Glaucous——Covered with a fine, waxy-like covering (bloom) which rubs
off easily.

Globose.—Globe-shaped.

Globular.—Globe-shaped.

Glume.—General name for floral bract of grasses and sedges.

Gynecium.—The carpels taken collectively.

Hastate—Halberd-shaped; basal lobes diverging.

Head.—An indeterminate type of inflorescence in which the flowers are in
a dense cluster, as in Composite. i

Hermaphrodite (flowers).—Perfect, both stamens and pistils present.

Hyaline—Thin and very nearly transparent.

Hy pocotyl—That portion of the embryo stem below the cotyledons.

Hypogean (cotyledons).—Remaining underground, as in the pea.

Hypogynous.—Ovary superior; flower parts attached below the ovary.

Hilum.—The scar on a seed, marking the attachment of a seed to its stalk.

Hirsute.—Covered with stiff hairs.

Homogamy.—The anthers and stigmas mature at the same time.

Imbricated.—Overlapping.

Incised.—Cut rather deeply into sharp lobes.

Included (stamens).—Not extending beyond the surrounding parts.

Incumbent (cotyledons)—With the backs against the hypocotyl.

Indehiscent—Not splitting open.

Indigenous.—Native to the region of growth.

Inferior (ovary).—Below the other flower parts.

Infleced.—Bent inwards.

Inflorescence.—A flower cluster.

Integument.—Skin; coat or protecting layer.

Internode-—The interval between two adjacent nodes.

Intravaginal —Referring to branches in grasses which grow out between
the leaf sheath and the culm (stem).

Introrse—Turned inwards; usually referring to anthers which shed their
pollen towards the inside of the flower.

Involucel—A secondary involucre.

Invelucellate—Furnished with involucels.

Involucrate-—Furnished with an involucre.

Involucre.—A series of bracts that subtend an inflorescence, as in Compos-
ite, cotton, etc.

Irregular (flower).—One or more of the parts of a series are dissimilar.

646 BOTANY OF CROP PLANTS

Keel.—Ridge, like the keel of a boat.

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 Composite.

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 Umbelliferez.

Mesocarp.—Middle layer of pericarp (ovary wall).

Mesocotyl_—Axis between base of coleoptile and grain, in grasses.

Micropyle—The opening between the ovule or seed coats.

Micros porangium.—Anther sac; case bearing microspores.

Monecious——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.

Nuilet—A small nut.

Ob.—A prefix signifying inversion.
Obcordate——Heart-shaped, with broad end at the tip.

GLOSSARY 647

Oblaie—Flattened at the ends.

Obovate.—Egg-shaped in outline, with the broader end at the tip.

Obsolete—Rudimentary, or entirely absent.

Obiuse.—Blunt or rounded at the apex.

Ocree@.—Sheathing stipules in Polygonacee.

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 papille. -

Pappus.—Bristle-like, awn-like scaly structures (modified calyx) at the tip
of the ovary in Composite.

Parenchyma.—A tissue made up of large, thin-walled cells with rather large
intercellular spaces.

Parietal—Pertaining to the wall; ovules that are attached to the wall of
the ovary are said to be parietal.

Parted.—Separated into parts nearly to the base.

Parthenocarpy.—A phenomenon in which the fruit matures without fertili-
zation of ovules.

Pedicellate —Possessing a pedicel.

Peduncle.—A stalk, either of an individual flower or of the inflorescence.

Pendant.—Hanging.

Pentamerous (flower).—Parts in fives.

Perfect (flower).—Possessing both stamens and pistils; hermaphroditic.

Perennial._—Living from year to 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.

Petalotd.—Petal-like.

Petiole-—The stalk of a leaf.

648 BOTANY OF CROP PLANTS

Phlem.—That portion of a vascular bundle which is largely concerned in
the transport of elaborated food material.

Phyllotaxy.—The arrangement of leaves upon a stem.

Pileole.—Coleoptile (which see).

Pinnate (leaf).—Leaflets arranged along the sides of an axis.

Pinnatifid —Pinnately cleft to the middle of the blade, or further.

Pistillate—Bearing pistils only.

Placenta.—The membrane or surface bearing ovules.

Plicate—Plaited.

Plumose.—Plume- or feather-like.

Plumule—The first bud in the young plant.

Polyadelphous (stamens).—Separate, or in more than two groups.

Polygamo-diecious—Bearing both perfect and imperfect flowers on the
same plant, with a tendency to become dicecious.

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.—1n which the stigmas of a flower are receptive before its anthers
shed their pollen.

Pubescence.—Fine, soft hairs.

Pubescent—Covered with fine, soft hairs.

Raceme.—Indeterminate type of inflorescence, in which the pedicels are
simple and one-flowered.

Racemose.—Raceme-like.

Rachilla.—The axis of a spikelet.

Rachis —The axis of a spike.

Radical.—Seeming to come from the root. Leaves arising from the base
of stem, close to the ground line, are said to be radical, as contrasted with
those on the stem (cauline).

Ray.—The branch of an umbel; marginal, ligulate flowers of a composite
head.

Receptacle——The end of the axis to which the floral organs are attached;
torus.

Reflexed—Turned back.

Regular (flower).—The parts of each whorl similar.

Reniform.—Kidney-shaped.

Reticulate—Netted.

Retrorse.—Tutned 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——Composed of cells that fit closely together and have
thick, hardened walls.

Scutellum.—Morphologically, the cotyledon of the grass embryo.

Segment.—A division of a leaf, fruit or flower.

Seminal.—Belonging to the seed.

Septum.—Partition or dividing wall.

Serrate-—With sharp teeth that point forward.

Sessile —Sitting; without a stalk.

Sheath—A tubular envelope about the stem, such as occurs in the leaves of
grasses.

Silicle—Similar to a silique, except that it is broader than long.

Silique.—Pod-like fruit of mustards, dehiscent, two-valved, and with two
parietal placentas; longer than broad.

Sinuate-—Wavy along the margin.

Sinus.—The space between two lobes.

Spathe.—A large bract or pair of bracts, subtending a spadix or flower
cluster.

Spatulate—Shape of a spatula or spoon.

Spicate.—Spike-like.

Spike-—An indeterminate type of inflorescence in which numerous sessile
flowers are borne on a rachis.

Spikelet.—The unit of inflorescence in grasses and sedges; a small spike.

Spinulose.—With small spines.

Squarrose.—With spreading parts.

Staminal.—Of or pertaining to stamens.

Staminate (flowers).—Bearing stamens only.

Staminodeal.—Pertaining to staminodia, 7.e., abortive and sterile stamens.

650 BOTANY OF CROP PLANTS

Standard.—The large petal in the flowers of Leguminose.

Sterile—Unproductive; without the reproductive elements.

Stipitate.—Provided with a stalk or stipe.

Stipules—Appendages at the base of the petiole.

Stipulate—Bearing stipules.

Stolon.—A trailing stem, above ground, that easily takes root at the nodes
when it touches the ground.

Stooling.—Productien of secondary branches from lowermost nodes, as in
grasses; tillering.

Strobile—Spike-like pistillate inflorescence of hop; also cone-like group of
sporophylls.

Stylar.—Of or pertaining to style.

Stylopodium.—Style-foot. The nectariferous gland at the base of the style
in the Umbelliferous fruit.

Sub.—Prefix signifying below, under, or almost, less than normal, in an
inferior degree.

Subtend.—To grow under, or be adjacent to, as a bract subtending a flower.

Subulate—Awl-shaped.

Sucker-—Rapidly growing shoots from roots or from stems underground.

Superior (flower).—Ovary appearing above the other parts of the flower.

Sym petaly—Petals united.

Suture.—A line of splitting.

Sympetalous —With the petals united to form a tube.

Syncarpy— Condition in which the carpels are united.

Synconium.—Fleshy fruit, in which the receptacle is hollow, and its inner
wall is lined with numerous flowers.

Syngenesious.—With the anthers united, as in Composite.

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.

Valvate (arrangement of parts in the bud)——The segments meet with
their edges, without any overlapping.

Valves.—One of the pieces into which a capsule splits.

Venation—The arrangement of veins.

Ventral.—On the lower side; surface of member turned toward the main
axis.

Vernation.— Arrangement of leaves in the bud.

Versatile (anther) —Filament is attached near middle of anther, so that
it can readily turn in any direction.

Vexillum.—Standard of the flower in Leguminose.

Viscid.—Sticky.

Vitta (pl. vitta)—Oil tubes in Umbellifer fruit.

Wing.—Lateral petal in the flower of Leguminose.
Whorl.—A group of organs arranged in a circle about a stem, and arising

from the same node.

Zygomor phy (flower).—See Irregular.

Abutilon, 506

Abyssinian oats, 130

Achene, 58

Achillea, 625

Acrospire, 144

Adjuki bean, 423

Adriatic figs, 275

Aegilops, 110

African cotton, 517
millet, 213

Agave, 47, 281

Agropyron repens, 70, 75

Agrostis, 81

Aino millet, 218, 219

Ale, 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

Alge, 62, 63

Algerian oat, 131

Allium, 231
ascalonicum, 231, 237, 238
cepa, 232, 237, 240

bulbellifera, 241
multiplicans, 241

fistulosum, 232, 237, 239
sativum, 236, 237

schoenoprasum, 231, 232, 237, 238

INDEX

Almond, 410
bitter, 411
hard-shelled, 411
oil, 411
soft-shelled, 411
sweet, 411
Aloe, 229
Alopecurus, 79
Alsike clover, 433, 434
Althea, 506
officinalis, 507
rosea, 507
Amarelles, 404
Amaryllidacee, 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
Amyedalus persica, 407
Amyris, 475
Andropogon, 87, 88
sorghum, 191
halepensis, 197
Angelica, 532
Angiosperme, 62
Animated oats, 131
Annual ring, 40
Annuals, 21, 70
Antennaria, 625

654 INDEX

Anther, 48, 49 Asparagus, laricinus, 244
Anthyllis, 429 lettuce, 632
Antipodals, 50 medeoloides, 246
Apium, 533, 538 officinalis, 244, 246
graveolens, 539, 540 plumosus, 246
rapaceum, 540 sprengeri, 246
key to principal species of, 539 Aster, 625, 628
leptophyllum, 539 Astragalus, 414
petroselinum, 539 Atriplex, 296
Apple, 367 hortensis, 299
American crab, 379 Atropa belladonna, 559
common, 379, 381 Auricle, 78
family, 366 Australian tobacco, 600
flowering crab, 379 Autogamy, 51, 94
narrow-leaved crab, 379 Autumn wood, 40
Siberian crab, 379 Avena, 88, 123
Soulard crab, 379, 381 abyssinica, 130
western crab, 379, 381 algeriensis, 131
Apricot, 405 barbata, 131
black, 407 brevis, 130
common, 405 byzantina, 130, 131
Japanese, 407 fatua, 128, 130, 131
purple, 407 nuda, 130, 131
Siberian, 407 orientalis, 125, 130, 131
Arabian alfalfa, 447 sativa, 89, 125, 126, 128, 130, 131
Arachis, hypogoea, 462 sterilis, 131
Aragallus, 414 strigosa, 130, 131
Arctostaphylos uva-ursi, 543 wiestii, 131 u
Arnica, 625, 628 Awns, 82
alpina, 600 Azalea, 543
Arrhenatherum elatius, 75
Artemisia, 625, 628 Bagasse, 227
Artichoke, globe, 639 Baltic alfalfa, 447
Jerusalem, 639 Bamboo, 69
Artificial gums, 185 Bambuse, 84
Artocarpus communis, 252 Banner, 414
Arundinaria, 84 oats, 130
Ascomycetes, 64 Banyan, 16
Asiatic cotton, 511, 512 tree, 267
Asparagus, 244 Barbe de Capuchin, 636
bean, 422, 458 Bark, 39, 40
falcatus, 244 Barley, 72, 88, 89, 135

“fern” 246 black, 145

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 |

INDEX

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

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

INDEX

Brassica, oleracea, gemmifera, 329, 330

viridis, 329, 330
rapa, 65, 328, 335
Bread-fruit, 252
Breaking, hemp, 280
Brebas, 275
Brewing process, 149
British gums, 185
Broad bean, 422, 426, 429
Broccoli, 334
Bromus inermis, 76
Broom corn, 88, 196, 197
-corn millet, 210, 213
Brown mustard, 339
Brush, 99
Brussel’s sprouts, 329, 330
Bryophytes, 62
Buchloe, 70
dactyloides, 76
Buckbean, 414
Buckwheat, 286, 289
common, 289
gray, 204
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

Buds, terminal, 24
supernumerary, 24
whorled, 25

Buffalo bur, 561
currant, 319

Bulbs, 32, 229

Bullaces, 400

Bulletin Smyrnas, 275

Bundle scar, 26

Bupleurum, 530

Cabbage, 328

common, 331

key to cultivated types of, 329

types of common head, 332

lettuce, 633
Calamondin orange, 487
Calendula, 625
Callirrhoé, 508
Calyx, 48
Cambium, 36

ring, 38
Camelina, 326
Campanulaceez, 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
Capparidacee, 326
Caprification, 273
Caprifig, 269, 272, 276
Capsaican, 595
Capsella, 326
Capsicum, 560, 595

annuum, 592

42

INDEX 657

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 F

Cercocarpus, 348

Cereals, 87

key to groups (genera) of, 87
small-grain seedlings of, 88
Chetochloa, 88, 210, 211
italica, 211, 216, 218
key to principal types of, 218
maximum, 218
moharium, 219

658

Cheetochloa, viridis, 211, 219
Chard, 312
Charlock, 339
Chasmogamy, 82
Chenopodiacee, 296
key to principal genera of, 297
Chenopodium, 297
Cherry, 401
SOUT, 403
sweet, 402
tomato, 587, 590
Chicasaw plum, 401
Chick pea, 467
Chicory, 628, 635, 636
Chilean strawberry, 363, 364
Chilli con carne, 596
Chinese cotton, 517
mustard, 340
pear, 384, 385
Chiogenes hispidula, 543
Chives, 237, 238
Chlorophycee, 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

INDEX

Citrus, key to principal species of, 479

limonia, 479, 481
medica, 479, 480
mitis, 487
nobilis, 480, 485
deliciosa, 485
unshiu, 485
sinensis, 480, 484
Cive, 237, 238
Cladophylls, 244

Classification and naming of plants, 60

Cleistogamy, 82
Close pollination, 51
Clover, 66, 432
Alsike, 433, 434
Berseem, 433
crimson, 433, 435
Dutch, 433
hop, 442, 449
giant, 453
Italian, 435
Japan, 465
Ladino, 434
mammoth, 433. 439, 441
meadow, 441
medium red, 441
Persian, 433
purple, 436
red, 433, 436
scarlet, 433, 435
Shaftal, 433
spotted bur, 442, 449
Swedish, 433, 434
sweet, 452
toothed bur, 4.42, 452
white, 433, 441
zigzag, 433, 441
Cloudberry, 350
Club mosses, 62
wheat, 111, 112, 114
Cob, 163
Coffee bean, 456
Coleanthus, 81

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, 111, 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, 111, 112, 114
Companion cells, 35
Compass plant, 632
Composite family, 625 .
Composite, 625
key to important genera of, 628
Concord grape, 501
Conium, 532
Convolvulacee, 554
key to important genera of, 555
Convolvulus, 554
Cordelia figs, 276
Corchorus capsularis, 281
olitorius, 281
Core line, 377
Coriander, 533
Corinth currants, sor
Cork cambium, 38
tissue, 38
Corms, 32
Corn, 157

INDEX

Corn, dent, 178, 180
flint, 178, 180
fodder, 185
oil, 184
pod, 178, 180
pop, 178, 180
soft, 178, 180
starchy sweet, 178, 180
sweet, 178, 180
starch, 184
stover, 186
xenia in, 172

Corolla, 48

Coronilla, 429

Cortex, 17

Corymb, 56

Cos lettuce, 633

Cotoneaster, 366

Cottolene, 524

Cotton, 508
African, 517
American, 512
Asiatic, 511, 512
Chinese, 517
Egyptian, 510
Guatemalan, 512
Nankin, 517
Red Peruvian, 517
Sea Island, 520

types and varieties of American, 521

Upland, 510, 520
Wild, 520

Cottonseed hulls, 524
meal, 524
oil, 524

Couloure of Muscat grape, 498

Cowberry, 550

Cowpea, 460

Crab-apple, American, 379
flowering, 379
narrow-leaved, 379
Siberian, 379
Soulard, 379, 381

659

660 INDEX

Crab-apple, western, 379, 381 Cucumis, sativus, anglicus, 621
Cranberry, 548 Sikkimensis, 621
American, 548 *Cucurbit, 606
European, 544 Cucurbita, 610, 612
large, 548 key to important species of, 612
mountain, 550 maxima, 612, 613
small, 548, 549 moschata, 612, 613
types of, 549 pepo, 612, 613
Crategus, 366, 367 ovipera, 613
Creeping snowberry, 543 Cucurbitacez, 606
wintergreen, 543 key to principal genera of, 610
Crimson clover, 433, 435 Culms, 72
Cross pollination, 52 Currant tomato, 587
artificial, 95 Currants, American black, 319, 320
Crown vetch, 429 flowering, 319, 320
Crucifere, 323 Buffalo, 319
key to principal genera of, 326 European black, 319, 320
Cucumber, 615, 617, 620 golden, 319
common field, 620, 621 Missouri, 319
English forcing, 621 red, 320
Jerusalem, 617 white, 320
musk, 620 Cushaw, 612, 615
prickly, 617 Cuticle, 44
Sikkim, 621 Cutting lettuce, 633
squirting, 606 Cyanophycee, 63
snake, 620 Cyctanthera, 608
star, 606, 620 Cydonia, 388
wild, 606 oblonga, 388
Cucumis, 610 varieties of, 388
anguria, 617, 620, 622 Cymopteris, 532
dipsaceus, 613 Cynara scolymus, 639
key to principal species of, 617 Cyperacee, 85
melo, 617, 618 Cyphomandra betacea, 592
var. acidulus, 620 Cypress vine, 554
cantalupensis, 618 Cytase, 142
chito, 620 Cytoplasm, 6
dudaim, 620 ;
flexuosus, 618, 620 Dahlia, 625
inodorus, 619 Dakota vetch, 429
reticulatus, 618 Damson, 400
saccharinus, 618 Dandelion, 628
moschata, 620 Dangleberry, 547

sativus, 617, 620 Danish ball head cabbages, 332

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
Dioscoreacee, 556
Disk flowers, 627
Distichlis, 55
Dock, 284
Dolichos bean, 422
Domestic onions, 243
Double fertilization, 53
Dracena, 229
Dried apples, 383
Drosera, 47
Drumhead cabbages, 332
Drupe, 393
Drupacez, 391
Duboisia hopwoodii, 600
Duckweed, 2
Dukes, 403
Durra, 196, 197
Durum wheat, 89, 111, 112, 113
Dutch case-knife bean, 423
clover, 433
Dwarf bilberry, 546 .

INDEX 661

Dwarf broom corn, 200

purple eggplant, 587
Dye-weed, 414

Ear, 162
Farly 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, 110
Eleusine coracana, 210
Elodea, 29
Embryo, 96
sac, 50
Emmer, 89, 111, 112, 113
Endive, 636
Endocarp, 58
Endodermis, 17, 57, 96, 102
English currants, 501
Entire wheat, 108
Epiblast, 104
Epidermis, 34
Epigeza repens, 543
Epiphyte, 28
Episperm, 101
Equisetales, 64
Frect-eared barley, 147
Ericacex, 543
Erigeron, 625, 628

662

Erinocyce figs, 275

Eriogonum, 285, 286

Eryngium, 530

Euchlena mexicana, 181, 182

European black currant, 319, 320
cranberry, 544
gooseberries, 321
raspberry, 357
strawberry, 363, 364

Eurotia, 297

Evergreen or fire thorn, 366

Everlasting pea, 432

Exocarp, 58

“Eyes,” 31

Fagopyrum, 286
emarginatum, 294
tataricum, 293
vulgare, 289

False flax, 326
Solomon’s seal, 21

Fan barley, 146

Farkleberry, 543

Fennel, 533

Fenugreek, 467

Fermentation, 150

Fern plants, 62

Fertilization, 52

Festuca ovina, 79
pratensis, 76

Fiber flax, 473
of cotton, 514

Ficus, 267
aurea, 267, 268
benghalensis, 267
brevifolia, 268
carica, 268, 269
elastica, 252
Teligiosa, 267

Field cucumber, 621
pea, 418, 420

Fig, 267
Adriatic, 275

INDEX

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

Feeniculum, 533

INDEX

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, 418 ,
lemon, 620
radish, 341
tomato, 590
Garlic, 236, 237
Gaultheria, 543
Gaylussacia, 543, 545, 547
brachycera, 547
dumosa, 547
frondosa, 547
key to North American species of,
_ 547
resinosa, 547

Gaylussacia, ursina, 547
Geitonogamy, 51
Generative nucleus, 50
Genista, 414
Geotropism, 73
German alfalfa, 447
celery, 540
millet, 218, 219
Gherkin, 622
Giant clover, 453, 563
Girasole, 639
Gleditsia, 414
Gliadin, 105
Globe artichoke, 639
onions, 241
Globulin, 105
Glucose, 184
Glume, flowering, 80
Glumes, 79, 80
Gluten, 102, 106, 155
meal, 186
Glutenin, 106
Glycyrrhiza, 414
Golden currant, 319
fig, 267
wonder millet, 218, 219
Goldenrod, 625
Goober, 462
Gooseberry family, 316
gourd, 617
Gooseberries, 321
American, 321
European, 321
Goosefoot, 296
family, 296
Goose wheats, 113
Gossypium, 508
_ barbadense, 519, 520
hirsutum, 517, 518, 520
Gossypol, 524
Gourd, 610, 613
tamily, bob
gooseberry, 617

663

664

Gourd, winter, 615

Grafting, 36

Graham flour, 108

Grain, 83
coats, 96

Graminez, 69

Granules, 8

Grape, 492
Catawba, sor
Concord, 501
Delaware, sor
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

INDEX

Grossulariacee, 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
Gymnosperme, 62

Hackling, hemp, 280
Hairs, basal, 92
Hairy vetch, 427, 430
Halophyte, 296
Head, 56
lettuce, 633
Hearts, 403
Heath family, 543
Hedysare, 415
Helianthus, 628
tuberosus, 639
Hemp, 252, 276
sisal, 281
tow, 280
Hennequin, 281
Hepatice, 64
Herb, 2
Hesperidium, 478
Heterostyly, 292
Hibiscus, 506
esculentus, 507, 527
syriacus, 508
High-bush blackberry, 354
blueberry, 547, 550
Hog millet, 213
Hollyhock, 508
Homalocenchrus, 70, 81
Homogamy, 169
Honduras rice, 206

Hooded barley, 136, 137, 145, 146

Hop, 33, 252

INDEX

Hop, clover, 442, 449
-meal, 264
-tree, 475
Hordeun, 88, 135
distichon, 135, 136, 137, 143, 145
erectum, 147
nudum, 146
nutans, 146, 147
zeocriton, 146
spontaneum, 148
vulgare, 144,
coeleste, 145
coerulescens, 145
hexastichon, 136, 137, 143, 144,
146
intermedium, 137, 143, 145, 146
nigrum, 145
pallidum, 143, 145, 146
trifurcatum, 136, 137, 145, 146
Horse millet, 213
nettle, 560
Horseradish, 345
Horsetails, 62
Hortulana plum, 400
Hosackia, 429
Hubbard squash, 614
Huckleberry, 547
black, 547, 550
blue, 546, 547
box, 547
bush, 547
Carolina, 547
dwarf, 547.
family, 543
high bush, 547
southern black, 544
swamp, $47
Hull-less Jerusalem barley, 145
oats, 130
Humulus, 252, 258
japonicus, 265
lupulus, 258
neomexicanus, 265

665

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
Tice, 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

Juncacezx, 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

INDEX

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

Leguminose, 413

key to principal genera of, 416

Lemma, 80

Lemon, 481

Ichang, 487

Lenticel, 27

Lepidium, 326

Lespedeza striata, 465

Lettuce, 628

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
Ligulifiore, 627
Ligustrum, 551
Lilac, 551
Liliacee, 229
Lilium, 229
Lily, 229
family, 229
Lima bean, 423, 424
Lime, 483
Limequat, 483
Linacee, 469
Linen, 473
Linoleum, 473
Linseed oil, 473
Linum, 470
catharticum, 469
usitatissimum, 470
Llanos, 69
Liverworts, 62
Lobelia inflata, 600
Lobfigs, 275
Locks, 514
Loco, 414
Locust, 414
bean, 422
Lodicules, 80
Lodging, 72
Loganberry, 358
Lombard plums, 399
Long-cluster blackberry, 354
Loose-cluster blackberry, 354

INDEX 667

Lotus corniculatus, 466
Low black blueberry, 546
blueberry, 546
+ bush blueberry, 550
Luffa, 613
Lupines, 465
Lupinus, 465
Lupulin, 264
glands, 264
Lupuline, 266
Lycium, 559
Lycopersicum, 587
esculentum, cerasiforme, 587
grandifolium, 587, 588
pimpinellifolium, 587, 588
pytiforme, 587
validum, 587
vulgare, 590
Lycopodiales, 64

Macaroni, 118
wheats, 113
Macounastrum, 284
Maiz de coyote, 179
Maize, 88, 157
Male nuclei, 50
Mallow family, 505
Malting, 149
Malus, 366, 367
angustifolia, 379
baccata, 379
coronaria, 379
floribunda, 379
ioensis, 379, 381
key to principal species of, 379
soulardi, 379, 381
sylvestris, 379, 381
Malva, 507, 508
Malvaceae, 505
key to important genera of, 508
Mamme, 272
Mammoni, 272

668

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 californica, 610
Melilot, 453
Melilotus, 452

INDEX

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

Mesembryacez, 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

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
Moracee, 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, 255, 257
family, 252
paper, 254

INDEX

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, 111, 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

669

670

Nicotiana, tabacum, 597
tomentosa, 596
wigandioides, 596

Nodding barley, 147

Node, 22

Nodes, 72

Non-saccharine sorghums, 196

Northern dewberry, 65, 356
fox grape, 499, 500

Nucellus, 50, 102

Nucleoli, 6

Nucleus, 6, 8.

Nurse crop, 149

Oats, 88, 89, 123
Abyssinian, 130
Algerian, 131
animated, 131
banner, 130.
fly, 131
hull-less, 130
mane, 130
Mediterranean, 130
naked, 130
panicle, 130
rough, 131
short, 130
side, 130
single, 126
sterile, 131
Tatarian, 130
twin, 126
wild, 130

Ochrus, 432

Ocrea, 284

Oil cake, 473
meal, 473

Okra, 527

Old World plums, 397

Oleacez, 551

Olea europocea, 551

Oleomargarine, 524

INDEX

Olive, 551
family, 551
Onion, 231, 240
common, 232, 237
Egyptian, 241, 242
multiplier, 241, 242
perennial tree, 243
potato, 241
top, 241, 242
free, 241, 242
Welsh, 231, 239
Onions, types of, 241
composition of, 243
uses of, 244
Onobrychis viciefolia, 465
Ophioglossales, 64
Orache, 299
Orange, blood, 484
Calamondin, 487
common, 484
king, 485
mandarin, 485
Mediterranean, 484
navel, 484
Satsuma, 485
Seville, 487
sour, 487
Spanish, 484
sweet, 484
trifoliate, 489
Unshiu, 485
Organs, 4
absorptive, 4
reproductive, 4
Ornamental beet, 301
Ornithopus sativus, 465
Oryza, 81, 87, 88
‘ glutinosa, 204
granulata, 206
officinalis, 206
sativa, 200, 206
utilissima, 206
communis, 206

Oryza, sativa, minuta, 206
Osage orange, 252
Ovary, 48
inferior, 54
superior, 54
wall, ror
Ovules, 48, 50
Oxypolis, 530
Oxyria digyna, 284
Oyster plant, 633
Spanish, 635

Pacific Coast dewberry, 352
Painted lady bean, 423
Palea, 80
Palet, 80
Palisade tissue, 44
Panicle, 56, 79
oats, 130
Panicum, 210
miliaceum, 210, 213
compactum, 215
contractum, 215
effusum, 215
Papaveracee, 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

INDEX 671

Pea, field, 418, 420
flat-podded, 432
garden, 418
perennial, 432
shelling, 418
sugar, 418
Tangier, 432
wild, 432

Peach, 407

Peacock barley, 146

Peanut, 462
butter, 464
meal, 465
oil, 465

Pear, 384
Chinese, 384, 385
common, 384, 385
Japanese, 384, 385
sand, 384, 385
tomato, 587

Pearl barley, 149
millet, 211

Peepul tree, 267

Pencilaria, 213

Pennisetum, 88, 210
spicatum, 211

Penny cress, 326

Pepino, 561

Pepo, 608

Pepper, 592
Cayenne, 595
Tabasco, 595
vine, 492

Perennial, 20, 70
pea, 432
tree onions, 243

Perianth, 49

Periblem, 17

Pericarp, 101

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

Phzophycee, 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, 1

fundamental internal structure of, 4

cell, 4

INDEX

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, 7¢
Poacee, 69
Pod, 58
corn, 178, 180
Polar nuclei, 50
Polish wheat, 111, 112, 113
Pollen grains, 48, 52
mother cells, so
tube, 52
Pollination, 51
Polygonacez, 284
key to principal genera, 286
Polygonum, 284
Pomaceez, 366
key to important genera of, 367
Pome, 366
Pomelo, 485
Poncirus, 476, 489
trifoliata, 489
Pop corn, 178, 180
Poppy family, 326
Pot-herb mustard, 340
Potamogeton, 29
Potato, 561
family, 559
onions, 241

INDEX 673

*otentilla, 348 Psedera tricuspidata, 33
?oulard wheat, 111, 112 Pseudomonas radicicola, 413
?rickly ash, 475 Psilotales, 64
cucumber, 617 Ptelea, 475
Privet, 551 Pteridophytes, 62
Profichi, 272 Pumpkin, 613
Prophyllum, 80 field, 613
Prop roots, 16, 159 mammoth, 615
Proso, 213 Valparaiso, 615
millet, 210 Purple apricot, 407
Protandry, 170 cane raspberry, 357
Protease, 142 clover, 436
Proteose, 105 vetch, 428
Protogyny, 170 Pyrus, 384
Protoplasm, 9 communis, 384, 385
Protoplasmic membrane, 6 serotina culta, 384, 385
Protoplast, 6
Prunes, 398 Quackgrass, 21, 70
Prunus, 394 Quamoclit quamoclit, 554
americana, 400 Quince, 388
amygdalus, 410
angustifolia, 401 Rabbit-brush, 625
armeniaca, 405 Raceme, 56, 78
avium, 402 Rachilla, 79
besseyi, 404 Rachis, 79, 92
cerasifera, 400 Radicula, 344
cerasus, 402, 403 armoracia, 345
cuneata, 404 nasturtium-aquaticum, 345
dasycarpa, 407 Radicle, 57
domestica, 398 Radish, 341
emarginata, 404 garden, 341
hortulana, 400 rat-tailed, 343
insititia, 399 wild, 342
key to main groups of, 394 Ragi millet, 210
mahaleb, 404 Raisin grape, 499, 500
mume, 407 Raisins, 501
munsoniana, 401 Raphanus, 341
nigra, 401 caudatus, 343
pennsylvanica, 404 raphanistrum, 342
persica, 407 sativus, 341
pumila, 404 Raspberry, 357
sibirica, 407 American red, 357
triflora, 400 black cap, 357

43

674

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, :

Retting, 279

Rheum, 289
palmatum, 289
undulatum, 289

Rhizoctonia, 569

Rhizomes, 29, 75

Rhododendron, 543

Rhodophycez, 63

Rhubarb, 286

Ribes, americanum, 319, 320
aureum, 319, 320
grossularia, 319, 321
key to important species of, 319
nigrum, 319, 320
oxycanthoides, 319, 321
rubrum, 319, 320
vulgare, 319, 320

Rice, 88, 202
Canada, 206
cultivated, 206
large-kerneled, 206
small-kerneled, 206
wild, 206, 207

River bank grape, 499, 500

Robinia, 414

Rockmelons, 618

Root cap, 17

“crown, 157

INDEX

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, z, 10
adventitious, 11
development of, 10.
fibrous, 10, 11
primary, 10
tap, 14
temporary, 10
tubercles, 413

Roots adventitious, rz

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
Rosacez, 348

key to important genera of, 350

Rose family, 348

of Sharon, 508

Rough oats, 131
Rubus, 350, 353

hair, effect of external factors upon

development of, 20

argutus, 354, 355
bernardinus, 357

chamemorus, 350
cuneifolius, 354, 355
glaucifolius, 357
ideus, 357

invisus, 356

key to groups of, 353

INDEX 675

Rubus, leucodermis, 357 San Pedro figs, 275
microphyllus, 358 Sanicula, 532
neglectus, 358 Sarcobatus, 297
nigrobaccus, 354 Sarracenia, 47
albinus, 354 Sauerkraut, 332
sativus, 354 Satsuma orange, 485
occidentalis, 357 Savannahs, 69
strigosus, 357, 358 Savoy cabbages, 332
trivialis, 356 Scales, 78
villosus, 354, 356 Scallop, 613
roribaccus, 356 Scarlet clover, 433, 435
vitifolius, 352, 356, 358 runner bean, 423
Rue family, 475 strawberry, 363
Rumex, 284 vetch, 428
Runner, 13, 32, 76, 358 Schizomycetes, 63
Rushes, 85 Schizophytes, 63
Russian mulberry, 255 Schuster, 84
thistle, 47, 296 Scientific name, 64
vetch, 430 versus common name, 66
Rutabaga, 337 names, descriptive nature of, 66
Rutaceex, 475 Scion, 36
key to important genera of, 476 Scorzonera hispanica, 635
Rye, 88, 89, 153 Scouring rushes, 62
Scutching, hemp, 280
Saccharum officinarum, 225 Scutellum, 104
Sachs, 177 Sea Island cotton, 520, 521
Sage, 625, 628 Sea-kale beet, 312
Sainfoin, 465 Secale, 88, 153
Sake, 207 anatolicum, 155
Salicornia, 297 cereale, 29, 153
Salsify, 628 montanum, 155
black, 635 Second patent, 108
Spanish, 635 Secondary cortex, 38
yellow-flowered, 635 Sedges, 85
Salsola, 296 Seed ball, 306
Saltbush, 296 . coats, 57
Salt-grass, 55 germination of, 59
Salt wort, 47 leaves, 59
Samara, 551 plant body, size and form of, 2
Sand bur, 560 principal parts of, 1
blackberry, 354 Seeds, 57
grape, 499, 500 . Seedlings, 57

pear, 384, 385 Self-fertility, 372

676

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

INDEX

Sitopyros, 110
Six-rowed barley, 144
Small cranberry, 548, 549
Small-seeded flax, 473
Smilax, 244
Smith, 175
Smother crop, 149
Smyrna figs, 273, 275
Snake cucumber, 620
eggplant, 587
Soapweed, 229
Soft corn, 178, 180
Soja bean, 456
Solanacez, 559,
key to important genera of, 560
Solanum, 560
carolinense, 560, 561
chiloense, 561
commersonii, 561
dulcamara, 560, 561
eleagnifolium, 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
é key to principal types, 197
origin of, 197

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, 111, 112, 113
wheats, 111
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
Spireza, 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

INDEX 677

Squash, surhmer, 613
turban, 610, 612, 614
Valparaiso, 615

Squirting cucumber, 606

Stages, ripening, 97

Stamens, 48

Staminate inflorescence, 55

Standard, 414
broom corn, 200
patent, 108

Star cucumber, 606, 620

Starches, 177

Starchy endosperm, 103
sweet corn, 178, 180

Strawberry tomato, 592

Stele, 17

Stem, of dicot, 33 °

Stems, 22
aerial, 2

classification of, based upon their

medium of growth, 28

general characteristics of, 26
structure of, 33
underground, 2
work of, 41

Steppes, 69

Stewart, 167

Stigma, 48

Stipules, 42

Stock, 36

Stolon, 32

Stomata, 45

Stone crop, 47

Stooling, 22, 73

Straight bread flour, 108

Strawberry blite, 296
Chilean, 363, 364
European, 363, 364
everlasting, 364
perpetual, 363, 364
scarlet, 363
Virginian, 363
wood, 364

678 INDEX

Streamside.grape, 66 Taraxacum, 628

Streptocheta, 81, 84 Tares, 429
Sturtevant, 159, 167, 178 Tassel, 55, 162
Stylar canal, 168 Tatarian oats, 130
Style, 48 Tatary buckwheat, 293
Stylopodium, 531 Teas’ weeping mulberry, 256
Succory, 635, 636 Tempering, 107
Suckers, 160 e Tendrils, 33
Sugar beet, 300, 301 Teneriffe, 243
Sugar cane, 225 Teosinte, 166, 181, 182
pea, 418 Testa, ror
Sultanas, sor Tetragonia expansa, 299
Summer figs, 275 Thallophytes, 62
grape, 499, 500 Thallus, 1
radishes, 243 plants, 62
wood, 40 Thermopsis, 414
Sundew, 47 Thin-leaved bilberry, 544
Sunflower, 625, 628 Thistle, 625, 628
Swedes, 337 family, 625
Swedish clover, 433, 434 Thlaspi, 326
Sweet clover, 452 Thorn apple, 366, 367
white, 454 Tillandsia usneoides, 28
yellow, 454 Tillering, 22, 73, 74
corn, 178, 180 Timothy, 75, 222
orange, 484 Tissue, 4
pea, leaf, 43 Tobacco, 596
potato, 555 Australian, 600
sorghums, 196 Indian, 600
Swiss chard, 312 mountain, 600
Synconium, 268 Persian, 600
Synergids, 50 “wild,” 600
Systema Nature, 61 Tomato, 587
Systematic botany, 60 cherry, 587, 590
Syringa, 551 currant, 587
garden, 590
Tabasco pepper, 595 husk, 592
Tall bilberry, 547 key to types of cultivated, sgt
Tangelo, 485 ‘ large leaf, 590
Tangerine, 485 pear or plum, 587, 590
Tangier pea, 432 strawberry, 592
Tangleberry, 547 tree, 592
Tansy mustard, 326 upright, 587, 590

Tap root system, 13 Toothed bur clover, 442, 452

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-groecum, 467
Tripping, of alfalfa flowers, 444
Triticum, 88, 91
cegilopoides, 112, 116
aestivum, III, 112, 114, 116
beeoticum, 112
capitatum, 116
compactum, 111, 112, 114, 116
dicoccum, I11, 112, 113, 116
dicoccoides, 114, 115, 116
durum, 111, 112, 113, 116
hermonis, 114
monococcum, 110, III, 112
ovata, 110
polonicum, 111, 112, 113, 116
spelta, 111, 112, 113, 116
thaoudar, 112

4

INDEX 679

Triticum, turgidum, 111, 113, 116
Tube nucleus, 50
Tuberization, fungus theory of, 569
Tubers, 30, 31
Tubuliflore, 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
Umbellifere, 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
cespitosum, 546
canadense, 66, 546, 550
corymbosum, 547, 550
key to chief fruit-bearing species of,

546
macrocarpon, 546, 548
Mmembranaceum, 544
myrtillus, 546
nigrum, 546, 550
ovalifolium, 547
oxycoccus, 546, 549
vacillans, 546, 550
virgatum, 544
vitis-idea, 546, 550

Vacciniacee, 543

680

Vacuole, 7

Variegated alfalfa, 447

Vascular bundles, 35
elements, 35

Vegetative activity, 1

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

INDEX

Virginian strawberry, 363
Vitacex, 491
key to important genera of, 492
Vitis, 492
estivalis, 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, gt
classification of the types of, 110
club, 111, 112, 113, 114
common bread, 111, 112, 113, 114
durum, 89, 111, 112, 113
grain, microscopic section, 100
hard, 106
naked, 111, 112
Polish, 111, 112, 113
Poulard, 111, 112, 113
soft, 106
spelt, 111, 112, 113
White blackberry, 354
clover, 433, 441
.currant, 320
mulberry, 255
mustard, 327, 340
Whortleberry, 546
Wild barnyard grass, 210
beet, 301

Wild cabbage, 328
cotton, 520
cucumber, 606
emmer, I14, 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, sso

Wood, 36
elements, functions of, 37
fibers, 36
parenchyma, 36
strawberry, 364

Woolly-podded vetch, 429

Wormwood, 625, 628

Xanthoxylum, 475
Xenogamy, 52, 95

INDEX

681

Xylem, 18, 36

Yams, 556
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