TESTING

AGRICULTURAL

and

VEGETABLE

SEEDS
vio

. 2>o

1280359

L-^
Manual for

TESTING AGRICULTURAL

AND VEGETABLE SEEDS

UNITED STATES DEPARTMENT OF AGRICULTURE

Production and Marketing Administration

in cooperation with the Bureau of

Plant Industry^ Soils^ and Agricultural Engineering

Most of the work on this manual was

performed under a project authorized by the

Research and Marketing Act of 1946

AGRICULTURE HANDBOOK No. 30

Washington, D. C, 1952

For sale by the Superintendent of Documents, U. S. Government Printing Office

Washington 25, D. C. - Price $4.00 (Buckram)
ACKNOWLEDGMENTS

This manual was prepared by personnel of the Seed Act Division,

Grain Branch, Production and Marketing Administration, with the

assistance of members of the Division of Forage Crops and Diseases,

Bureau of Plant Industry, Soils, and Agricultural Engineering, Agricultural Research Administration, U. S. Department of Agriculture.

The plan of the manual was developed by O. L. Justice who also supervised and coordinated its preparation and w^rote several sections.

Albina F. Musil prepared the section on seed identification and supervised the preparation of many of the drawings.

The original drawings of seeds were done by F. H. Hillman, the

late Helen H. Henry, and Regina O. Hughes. The following contributed to the preparation of the manual by Avriting one or more

sections : Alice M. Andersen, Harriet Cull, Vera C. Drake, Frieda L.

Wertman, Bruce Caldwell, Charles A. Kent, Jr., and Lawrence Zeleny.

Magdalene Brummit, Mary Haferkamp, Constance Sleeper, Lillian

Wessel, and other members of the Seed Act Division, assisted with the

preparation of the manuscript. W. A. Davidson and R. H. BlacJv

reviewed it and offered helpful suggestions.

Acknowledgment is made to numerous w^orkers in Federal, State,

Canadian, commercial, and private seed-testing laboratories. Their

contributions have been of inestimable value in the preparation of this

manual. Credit is also due certain firms that manufacture or handle

seed-testing equipment for supplying some of the photographs of

equipment.

Most of the work on this manual was performed under a project

authorized by the Agricultural Marketing Act of 1946 (RMA,

Title II).
1280359

PREFACE

In the field of seed technology there is a wealth of technical informa

tion that has never been broughttogether in a form immediately available to laboratory workers. Some of this information has been

published in journals and proceedings of associations and societies of

widely differing interests, and in mimeographed form, whereas some

has never been published. In order that much of the practical information may be readily available to seed technologists, instructions for

conducting laboratory tests and pertinent background information are

set forth in this publication.

With respect to the results obtainable in seed testing there are two

principal requirements: (1) The results should indicate, as nearly as

possible, the actual planting quality of the seed lot; and (2) the tests

should be made in such a manner that the results can be reproduced

within calculated limits. During the last 50 years seed testing in the

United States has developed to the extent that rather specific rules or

instructions for carrying out the tests have been devised and published.

These rules are the basic guides for officially testing seed in the administration of Federal and State seed laws and are generally followed by

private and commercial technologists as well. In spite of these specific

rules, however, wide variations frequently exist among laboratories,

with respect to test results on seeds of the same quality. One of the

principal reasons for these variations is the lack of detailed instructions for the application of the rules for seed testing.

This manual has been prepared primarily as a w^orking tool to be

used for instruction purposes aimed at reducing the variations in test

results. If used by seed technologists generally, the manual can serve

as an important instrument in standardizing procedures, equipment,

and interpretations with the result that these variations should decrease. It may also serve temporarily as an instruction manual in

agricultural colleges and provide the necessary incentive to encourage

additional colleges to offer instruction in seed technology, thus alleviating the present critical personnel situation.

Seed technology covers a broad field. It includes a knowledge of

seeds of agricultural, vegetable, flower, herb, orchard, and forest plants

as well as of equipment and supplies essential to testing. Owing to

the factthatthis manual has been prepared primarily for technologists

working on those kinds of commercial seeds which are subject to Federal and State regulation, the information contained herein is limited

to agricultural and vegetable seeds, domestic or imported.

An attempt has been made to present the information in the most

usable arrangement without undue repetition. To accomplish this

it seemed necessary to include in certain sections information applicable to many or all kinds of seeds and in other sections information

applicable to smaller but related groups of seeds. Those workers

and students who may be interested in more basic information pertaining to seeds will find three brief treatments near the back of the
IV PREFACE^

manual under the headings : "Developinent, Structure, and Hereditary

Characteristics of Seeds, "Physiology of Seeds," and "Pathological

Considerations in Seed Testing." In order to present the information

in a concise manner it was necessary to use certain technical and infrequently used common terms. Thus, a glossary of terms has been

provided for the reader on pages 319 to 327.

This manual supersedes Miscellaneous Publication No. 437, Testing Farm Seeds in Home and School^ published in 1942.
CONTENTS

Page

Introduction 1

Rules for testing seed 1

Federal Seed Act 3

State seed laws 3

Seed-testing laboratories in

the United States 4

Seed sampling and testing equipment 5

Sampling equipment 5

Air blast for cleaning seed

dividers 12

Equipment for purity testing.. _- 12

Equipment for germination

testing 21

Greenhouse 35

Filing cabinets ^ — 36

Obtaining the seed sample 37

Sampling the seed lot 37

Reducing the sample in the

laboratory 39

Care of samples 40

Proceduresfor determining purity

composition 42

Accommodations 42

The use of equipment 42

The purity separation 46

Separating seeds of similar

kinds and varieties 47

Interpretation of crop seed. 47

Interpretation of weed seed__ 49

Special tests and procedures. 52

Application of purity procedures

to specific groups of seeds 54

Gramineae (grass family) 55

Leguminosae (legume or pea

family) 73

Valerianaceae (valerian family)-- 80

Umbelliferae (carrot family). 80

Solanaceae (nightshade family) 80

Polygonaceae (buckwheat

family) 81

Malvaceae (mallow family). 81

Linaceae (ñax family) 81

Liliaceae (lily family) 82

Geraniaceae (geranium family) —- 82

Cucurbitaceae (cucurbit family) 82

Cruciferae (mustardfamily). 83

Compositae (composite family) 84

Chenopodiaceae, Cannabinaceae, and Aizoaceae (goosefoot, hemp, and carpetweed families) 84

Page

Procedures for determining germination 86

Definition and object 86

The kinds and use of substrata 86

Preparing the test 92

Provision and maintenance

of environmental conditions 94

Interpretation of the germination test 96

Methods of overcoming dormancy 101

Special procedures 103

Application of germination procedures to specific groups 107

Aizoaceae (carpetweed family) and Chenopodiaceae

(goosefoot family) 107

Compositae (composite or

sunflower family).. 113

Cruciferae (mustard family) _ 119

Cucurbitaceae (cucurbit

family) 124

Gramineae (grass family)... 126

Legiiminosae (legume or

pea family) 142

Liliaceae (lily family) 160

Linaceae (flax family) 162

Malvaceae (mallow family) _ . 164

Polygonaceae (knotweed

family), Solanaceae (nightshade family), Umbelliferae (carrot family), and

miscellaneous kinds in

other families 167

Examination for noxious-weed

seeds 172

Object and nature of test.. 172

State and regional lists of

noxious-weed seeds ._ 172

Size of sample 172

Conducting the examination. 173

Interpretation of seeds 174

Expressing the rate of occurrence 174

Origin of seeds 175

Importance of origin determination 175

Size of sample for origin determination 175

Evaluation of impurities 175

Major seed-producing regions 176

List of seed impurities available 177

V
VI CONTENTS

Page

Testing for trueness of variety. _ 178

Scope of variety testing 178

Purpose of variety testing__ 178

Authentic samples for controls 178

Number of plants to grow__ 178

Testing in the field 179

Testing in the greenhouse _ _ 180

Judging the crop 181

Testing for moisture 183

Basic methods 183

Practical methods 185

Tolerances 187

Definition and necessity of

tolerances 187

Probability or degree of certainty 188

Pure-seed tolerances 188

Germination tolerances 189

Noxious-weed seed tolerances 189

Tolerances for ñuorescence

tests and other 400- to

1,000-seed separations 189

Application of tolerances 190

Calculations, records, and reports 191

Calculation of laboratory

test results 191

Laboratory records 193

Reporting the results of

tests 193

Identification of seeds 194

(Also see List of Plant Names for Others

Which Are Illustrated Only)

Gramineae ( grass family) _ _ _ 195

Caryophyllaceae (pink family) 232

Cruciferae (mustard family) _ 233

Leguminosae (legume or pea

family) 237

Convolvulaceae (morningglory family) 258

Development, structure, and hereditary characteristics of

seeds 263

The flower 263

Development of the ovule__ 263

Development of the pollen

grain and the generative

cells 264

Fertilization 264

Types of ovules -_ 264

Development of the seed in

monocotyledonous plants- 265

Development of the seed in

dicotyledonous plants 269

The seed 271

Hereditary qualities of the

seed 271 Index

Page

Physiology of seeds 273

The resting seed 273

The process of germination^ _ 273

Environmental conditions

affecting germination 275

Physiology of dormancy 278

Retention of viability in

seeds 281

Duration of viability 282

Mechanics of germination-_ 283

Pathological considerations in

seed testing 284

Seeds as hosts and carriers of

organisms causing disease

and injury 284

How seed-borne organisms

are carried 285

Relation of host and parasite 285

Effect upon the host seed... 286

Methods 292

Partial list of pests and injury conditions 293

Literature cited 297

Selected references 300

Purity determination __ 300

Physiology and germination. 302

Identification of seeds.----- 310

Testing for variety 312

Pathological considerations- 312

Morphology 313

Samphng 314

Tolerances and statistics 315

Equipment 315

Origin 316

General 316

Available publications on seed

testing 318

Glossary 319

Appendix 328

Rules for testing saeds 328

Sample record and report

forms 369

List of botanical names 373

Index for identification,

purity, and germination-, 373

List of plant names 395

Index for identification,

purity, and germination.- 395

List of botanical and common

names 417

425
UNITED STATES DEPAETMENT OF

AGEICULTUKE

AGEICULTUEE H AND BOOK NO. 30

AVashington, D. C. October 1952

MANUAL FOR TESTING AGRICULTURAL

AND VEGETABLE SEEDS

Prepared by the Seed Act üwísion, Grain Branch

Production and Marketing Administration

in cooperation with the

Division of Forage Crops and Diseases

Bureau of Plant Industry, Soils, and Agricultural Engineering

Agricultural Research Administrâti07i

INTRODUCTION

O EED is both an important item in commerce and a basic commodity

^ in agriculture, being essential for the propagation of crops and perpetuation of germ plasm. It is of extreme importance that the grower

know something of the quality of the seeds he plants. However, it

is not possible for the average person interested in seeds to learn

much of their quality by visual examination. Thus, the responsibility of providing information pertaining to seed quality has been

placed upon the seed merchant, and State and Federal governments

ai^ charged with the responsibility of checking to determine whether

the requirements are carried out.

To meet these responsibilities, the seed must be tested ( 1 ) by the

seed merchant in order to label it properly, and (2) by the seed control official to determine whether it is correctly labeled when offered

for sale. The primary objective in seed testing is to obtain accurate

and reproducible results regarding the purity composition, rate

of occurrence of noxious-weed seeds, and percentage of seeds that

can be expected to produce normal plants under favorable conditions.

In some instances such additional information as presence of seedborne fungi, origin, or varietal purity, is desired. Thus, seed testing

provides information for: (1) Planting purposes; (2) labeling purposes; (3) establishing prices; and (4) seed control work.

RULES FOR TESTING SEED

The result of a test on a seed sample should be a fair measure of

its quality and the test should be made by such methods that the results

can be reproduced by other laboratories testing like samples. To

make the latter possible, rules for seed testing have been developed

and published. The present rules are rather specific in their require-
2 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

ments, which is essential if uniform test results are to be expected.

Although specific rules are desired, caution must be observed in developing them so as not to exclude the proper testing of seed stocks

which do not respond to the usual testing conditions for the kinds

under consideration. Frequently, seed lots of a given kind differ in

their germination requirements, the difference depending on such

factors as: (1) Length of time between harvest and test date; (2)

conditions during seed maturation; and (3) storage conditions subsequent to harvest.

The rules for seed testing must be practical and capable of application. Owing to the large number of samples that laboratories are expected to test, the methods must permit testing with a minimum of

effort and time on the part of the analyst, and the demands for early

test results usually require that the tests be completed within the least

number of days possible. Formerly, the work load in many laboratories was not heavy and many samples could be handled as minor

research problems, but that is not possible in the average laboratory

today.

The earliest rules for seed testing in the United States were published as Circular No. 34 of the Office of Experiment Stations, United

States Department of Agriculture, in 1897, under the title "Eules and

Apparatus for Seed Testing." There have been numerous revisions

and improvements in the rules since that time, some revisions having

been published by the United States Department of Agriculture and

some by the Association of Official Seed Analysts. Two sets of Rules

for Seed Testing are in use in the United States. These have been

developed jointly by the U. S. Department of Agriculture and the Association of Official Seed Analysts and are published separately by

each (^, 6) ? Owing to the close cooperation in developing the rules

there are only a few minor differences in the two sets of rules. Hence,

the expressions "Eules for Seed Testing" or "rules" as used in this

publication will refer to both sets of rules. These can be found on

pages 328 to 368 in this manual.

Seed-testing stations in other countries have their own rules for

seed testing. The Scandinavian countries have developed a set of

rules to be used in Denmark, Norway, and Sweden. The International

Seed Testing Association has had a set of international rules in effect

since 1934. These rules are rather general but are currently being

revised along the lines of the American and Canadian rules.

Improvement in the methods of testing seed is highly desirable. It

may include: (1) Reducing the total amount of effort required in

making the tests ; (2) completing tests within a shorter period of time ;

(3) obtaining more accurate and uniform results than present methods

permit; (4) new kinds of agricultural and vegetable seeds; and (5)

additional groups of seeds such as flower seeds and tree seeds. There

are two means of obtaining data for improving the methods of testing :

(1) By accumulation of results from routine testing, particularly when

more than one method is employed ; and (2) through research designed

to solve specific problems. Both methods have been important in

developing the present rules but most improvements in technique at

present result from research. This will probably continue to be the

case in the future.

^ Italic numbers in parentheses refer to Literature Cited, pp. 297 to 299.
TESTING AGRICULTURAL AND VEGETABLE SEEDS ó

FEDERAL SEED ACT

It is not within the scope of this manual to set out the complete

details of Federal and State laws and regulations relating to the sale,

transportation, and distribution of seed. The Federal Seed Act, enacted by the United States Congress in 1939, applies to imported seed

and to seed in interstate commerce.

IMPORTED SEED

Agricultural and vegetable seeds imported into the United States

must meet minimum standards for pure-live seeds, must not contain

more than 2 percent by weight of weed seeds, and must not contain

designated noxious-weed seeds in excess of the number specified in

the act. Imported alfalfa and red clover seeds must be stained to

indicate origin. Imported seed is not required to be labeled but if

labeled the information must not be false or misleading in any respect.

SEED IN INTERSTATE COMMERCE

Agricultural seed moving in interstate commerce is required to be

truthfully labeled to show: (1) The name of each kind, kind and

variety, or kind and type of agricultural seed present in excess of 5

percent; (2) percentages of pure seed, other crop seed, weed seed,

inert matter, germination, and hard seeds, when present; (3) the

name and rate of occurrence for each secondary or permissible UOXíOUST

weed seed and otherwise to comply with the noxious-weed seed requirements of the State into which the seed is shipped; (4) the date

the test was made to determine the percentages of germination and

hard seeds shown on the label, and the test is required to have been

made within a 5-month period prior to shipment; (5) lot designation;

and (6) name and address of shipper or name and address of consignee

together with the shipper's code designation.

Vegetable seed is required to be labeled to show: (1) The name of

the kind and variety; and (2) name and address of shipper or name

and address of the consignee together with the shipper's code designation. Vegetable seed must meet the minimum germination standards

established under the Federal Seed Act, or, if below standard, must

be labeled to show the percentage of germination, the percentage of

hard seed when present, the date of test, and the words "Below

Standard."

STATE SEED LAWS

The interstate section of the Federal Seed Act is frequently referred

to as a Truth-in-Labeling Law and represents the pattern of the State

seed laws. However, there is considerable variation in detail among

the State seed laws. For example, a few States require that the name

of the variety be given on the label for agricultural seeds. Some

require that the germination test shall not have been made more than

6 months prior to the date the seed is sold whereas other States permit

as much as 12 months to elapse after the test and before sale, and a

few do not make any reference to the date of test.

The State seed laws differ more in their noxious-weed seed requirements than in any other respect. This difference applies to both the

manner in which the amounts of noxious-weed seeds are expressed and

in the species considered noxious. Although each State has its indi-
4 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

vidual list of noxious-weed seeds some measure of success has been

attained with respect to establishing noxious-weed lists on a regional

basis.

Most States have a list of noxious-weed seeds which are prohibited,

and another list of seeds which are permitted up to an established

maximum provided the name and rate of occurrence of each kind

appear on the label. In some States the former are referred to as

"Prohibited Weeds" and in other States as "Primary Noxious Weeds."

Weeds falling into the second list are usually referred to as "Secondary

Noxious Weeds." The early seed laws were enacted to protect the

consumer, but more recently it has become evident that good seed laws

coupled with good administration offer protection to the scrupulous

seedsman as well as to his ultimate customer.

SEED-TESTING LABORATORIES IN THE UNITED STATES

In order to carry out the intent of the laws pertaining to seeds,

each State or Federal agency charged with admiiiistering such laws

must have means of testing seed samples. The seed laws in most

States are administered by the State departments of agriculture,- although in a few States administration of such laws is the responsibility of the State colleges of agriculture or experiment stations. In

approximately one-half of the States the official seed-testing laboratories are located in the State departments of agriculture, whereas

in approximately 20 States they are located at the State colleges of

agriculture or experiment stations. In 4 States other provisions are

made for testing.

The Federal Seed Act is administered by the Grain Branch, Production and Marketing Administration, U. S. Department of Agriculture. All testing incident to the administration of the act is

carried out by the Grain Branch, except that a few samples are tested

annually by the seed laboratory of the Board of Commissioners of

Agriculture and Marketing, Honolulu, T. H. Federal stations are

located at Beltsville, Md., NeAv Brunswick, N. J., Minneapolis, Minn.,

Montgomery, Ala., and Kansas City, Mo. Federal-State cooperative

stations are located at Sacramento, Calif., and Corvallis, Oreg.

The Federal seed laboratories do not conduct service tests for the^

general public but most State labora^tories perform this service insofar

as their personnel and facilities permit. In some States, service testing is limited to residents of the State but in other States there are

no such restrictions. A high percentage of the seed in commercial

channels is tested by commercial and private technologists. Commercial laboratories are operated on a fee basis to serve the general

public, particularly such groups as seedsmen and farmers. Private

laboratories are operated by seed firms, solely or principally for their

own use. Since the test results obtained by commercial and private

analysts are ordinarily used for labeling seed in commercial channels,

such analysts find it necessary to follow the official rules for seed

testing.
SEED SAMPLING AND TESTING EQUIPMENT

SAMPLING EQUIPMENT

TRIERS OR SAMPLERS

Triers are commonly used in sampling seeds in bags and bins. The

most commonly used instrument is known as a sleeve-type trier which

consists of a hollow brass tube inside a closely fitting outer shell or

sleeve. The tube and sleeve have open slots in their walls so that

when the tube is turned until the slots in the tube and sleeve are in

line, seeds can flow into the cavity of the tube, and when the tube

is given a half turn the openings are closed. The tubes vary in length

and diameter, being designed for different kinds of seed and sizes of

bags. In sampling seed in bags the following sizes of triers have been

found suitable: For clovers and other small, free-flowing seed, 30-inch

trier with outside diameter of 14 i^^^h and 9 slots ; for cereals, 30-inch

trier with outside diameter of 1 inch and 6 slots. The 11-inch bag

trier which is only % inch in diameter may be used to advantage

in sampling small bags of clover and similar seeds. It is a sleevetype trier with a single slot in the outer casing near the ^pointed end.

Seed is admitted into the tube by withdrawing the tube past the slot.

This trier makes a very small hole which is important in sampling

seed in cotton bags ; however, it should not be used in sampling large

bags as the trier is not long enough to reach the most distant parts.

Bin samplers are constructed on the same principle as seed triers

but are much larger, ranging up to 63 inches in length and 11/^ inches

in diameter with 6 or 9 slots. Many seed inspectors use a 6-, 9-,

or 12-inch thief-type trier. This trier is not described because its

construction and size do not permit sampling in accordance with the

rules. Different types of triers are illustrated in figure 1.

DIVmERS

Soil divider.—Perhaps the most simply constructed divider suitable

for seed-testing work is the soil sampler which consists of a hopper

with attached channels or ducts, a frame to hold the hopper, two receiving pans and a pouring pan (fig. 2). Ducts or channels, i/^ inch

wide, lead from the hopper to the collecting pans. There are 18 of

these channel^, alternate ones leading to opposite sides. The maximum

dimensions ate : 14 inches long ; 10 inches wide ; and 11 inches kigli.

In using the divider the seed is scattered fairly evenly in a pouring

pan the length of the hopper and poured in at approximately equal

ratés along the entire length of the hopper. This sampler is used in

dividing samples of large seeds and chaffy grass seeds.

Boemer dividers,—The most commonly used mechanical seed dividers at the present time are the Boerner dividers. There are two

dividers which differ in size, but which are made on the same plan.

The essential parts consist of a hopper, inverted cone, and a series of

baffles directing the seed into two spouts. The baffles form alternate
6 AGRICULTURE HANDBOOK NO. 3 0, V. S. DEPT. OF AGRICULTURE

FIGURE 1.—Sleeve-type seed and grain triers. From left to right : Bin sampler

for grain ; bag trier for grain ; bag trier for clovers and other small seed ;

11-inch bag trier ; two thief-type triers that are not recommended.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 7

channels and spaces of equal width. They are arranged in a circle at

their summit and are directed inward and downward, the channels

leading to one spout and the spaces to an opposite spout. A valve or

gate at the base of the liopper retains the seed. When the valve is

opened the seed falls by gravity over tlie inverted cone where it is

evenly distributed to the channels and spaces, then passes through the

spouts into the seed pans.

In the large divider, designed for large seeds and grains, there are

19 channels and 19 spaces, each 1 inch wide. In the small divider,

designed for small free-flowing seeds, there are 22 channels and 22

spaces, each %g incli wide. Tlie over-all dimensions of the dividers

are as follows : Large divider, 32 inches high and 14.5 inches in diameter ; small divider, 16 inches high and 6 inches in diameter.

FIGURE 2.—Soil divider. A good tlivider lor large seeds, sueli as corn and beans,

and for chaffy grass seeds.

The following construction features should be observed when purchasing a Boerner divider: (1) The sliding valve should move with

ease but not allow seeds to pass along the edges when closed ; (2) sharp

angles should be reduced to a minimum and there should be no small

openings or rough edges on surfaces over which seeds flow. Seeds may

lodge in these angles and crevices and be carried into other samples.

The Boerner dividers are illustrated in figure 3.

Kny-Scheerer divider.—In the Kny-Scheerer divider the seed is

spun around in a rotating hopper and divided into two approximately

equal parts as it flows downward. The funnel-shaped hopper with

valve is rotated by a hand-operated crank. While in motion the seeds

are spun around with the hopper, and the valve is gradually opened

either by screw adjustment or by manual manipulation. As the seed

falls downward it is divided into two parts by stationary baffles and

passes through spouts into the receiving pans (fig. 4).
8 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Garnet frecision divider.—The Garnet divider (fig. 5) makes use oí

centrifugal force to mix and scatter the seeds over the dividing surface. In this divider the seed flows downward tlirough a hopper on

a shallow rubber cup. Upon rotation of the rubber cup by an electric

motor the seeds are thrown out by centrifugal force and fall downM'ard. The circle or area where the seeds fall is equally divided into

two parts by a stationary baffle so that one-half the seeds fall in one

spout and one-half in the otlier spout. In using this divider care

must be exercised in dividing very small samples as it is possible

that a majority of the seeds may come out in one spout.

FiGUKE 3.—Boeruer dividers : A, Designed lor dividing cereals and other large

seed ; B, designed for clovers and otlier small, free-flowing seed.

Ilay-Bates divider.—Tliis is a rather large divider intended primarily to eliminate undesirable dust when dividing seeds such as beet

and chaffy grasses, and those treated with poisonous fungicides (fig. 6).

The principle involved in dividing the sample is similar to that employed in the Boerner divider. However, instead of a circular arrangement of the channels, the construction and arrangement are similar to

those of the soil divider previously described. Tlie baffles which divide

the neck of the hopper into equidistant channels are built into the

hopper. This entire unit can be removed and replaced with hoppers

having channels designed for three sizes of seeds. The seeds fall downward for a considerable distance through two cavities, each leading to
TESTING AGRICULTURAL AND VEGETABLE SEEDS 9

a separate seed pan. At the rear of the divider is a small vacuum

attachment operated by an electric motor, the speed of which is regulated by a rheostat. In operation, the vacuum motor is turned on

and the rheostat adjusted so there will be a slight suction in the

FIGURE 4.—Kny-Scheerer divider.

cavities through which the seed falls. Any dust extracted from the

seed is collected in a bag attached to the vacuum outlet.

Ottawa divider.—The Ottawa divider (fig. 7) is a precision divider

intended for use with free-flowing seeds the size of flax and smaller.

The seed is introduced into a hopper and then falls down a shaftlike
10 AGRICULTURE HANDBOOK KO. 30, U. S. DEPT. OF AGRICULTURE

column during which time it undergoes repeated divisions and recombinations to insure proper mixing. Near the bottom of the column

is a movable baffle resting on knife edges of regular balance constructi(m. The tilt of the baffle determines the proportion of seed that will

FiGUEE 5.—Garnet divider ; also known as Garnet precision divider.

flow into each of the two seed pans. To divide the sample into two

parts of equal weight the seed is allowed to run gently through the

leveled divider without any further adjustment. Unequal divisions

can be made as desired by adding weights to one of the pans.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 11

FiGUKE 6.—Hay-Bates divider. Seed pouring pan on left.

FiGTJEE 7.—Ottawa divider: A, front view; B, dividing column swung around;

G, details of balance construction and hopper. Explanatory legend : sh, seed

hopper ; pr, pointer ; hh, balance beam ; pn, pan ; Is, leveling screws ; Ip, lock pin ;

I, level ; sba, spout and balance mechanism swing away ; mb, movable baffle ;

me, mounting for knife-edge and indicator ; «ft, seating for movable knife-edge

of movable baffle ; h, hopper ; s, spout.

»ñTllS—52 3
12 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

AIR BLAST FOR CLEANING SEED DIVIDERS

It is imperative that seed from one sample not become commingled

with other samples. However, this is always a possibility in dividing

the samples unless the greatest precaution is taken to dislodge any

seed tliat may remain in the divider. Air blast can be used to clean

this equipment. Laboratories which are housed in regular laboratoiy

buildings usually have air lines hooked up with a central pumping

system. In the absence of a central system a small portable electric

blower can be obtained. A convenient and useful portable blower is

illustrated in figure 8.

k

FIGURE S.—Blower for use in cleiining seed divklers.

EQUIPMENT FOR PURITY TESTING

WORKBOARD

Tables or desks at which analysts make purity tests should average

30 or 31 inches high. In order to minimize fatigue of the eyes, neck,

and shoulders the work must be elevated 3 to 6 inches above the level

of the table top. This is accomplished by a workboard which is illustrated in figure 9. The height of the workboard should be constructed

in accordance with the individual's needs, and the slope of the arm

rests is important in reducing fatigue of the arms and shoulders.

There are several modifications of the workboard, especially with

respect to the covering. The top of the workboard illustrated in

figure 9 is constructed of soft wood so that thumbtacks may be used

to fasten a heavy grade of paper on which the seed is placed. Some
TESTING AGRICULTURAL AND VEGETABLE SEEDS 13

analysts prefer a glass slab as a working surface. If plate glass is

used, it should be covered with nonglare and nonreflecting paper. A

small drawer may be built into the workboard to hold forceps, lenses,

and similar instruments or as a receptacle for the pure seed component.

The arm rests may be attached to the body of the workboard at about

a 30-degree angle from the horizontal. This provide,s support to the

arms for a greater distance than in the model illustrated.

FIGURE 9.—Workboard, the working surface of which is made of soft wood and

covered with paper as described in text.

FORCEPS AND SPATULA

Fine-pointed forceps are necessary for testing small seeds and are

usually preferred over blunt forceps wlien tasting larger seeds. Forceps are not standardized but for purity work they should be slightly

flexible, ofl'er slight resistance to pressure, and should be about as sharp

as a common pin. Some analysts prefer to make the separations witli

a spatula or horn.

MAGNIFIERS

A 5 X -, 6 X -, or 7 X -hand lens with wide field is necessary and will

meet most of the seed analyst's requirements. The doublet-type

magnifier is not satisfactory because the focal distance is so short

the observer's hand and head usually cast a shadow on the seed being

analyzed and the correction is not sufficient to give a plane field. The

triple aplanat (triplet) magnifier is preferred and usually has good

correction.

Reading glasses may be useful in making noxious-weed seed examinations on seeds the size of vetch and cereals. There are reading

glasses (1) with handle for holding in the hand, (2) mounted on an

adjustable stand, and (3) mounted on a flexible arm attached to a

heavy base. The principal objection to reading glasses is the curved

field which they give, resulting in eyestrain.

MICROSCOPE

A wide-fi«ld stereoscopi« microscope with at least 3 pairs of objectives giving magnifications of approximately 10 to 15, 20 to 40, and 50

to 75 is essential. Microscopes with a revolving nosepiece are preferable to those having removable objectives. A compound microscope

is not esseistial for jjurity work.

SCALES AND BALANCES

A scale having a capacity of at least 1,000 grams and accurate to

0.5 gram is essential. A rapid-acting scale is highly desirable. Table
14 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

models having a calibrated face behind a movable indicator are available. The weights can be read almost immediately in grams to an

accuracy of 0.5 gram.

A torsion balance having a capacity up to approximately 120 grams

and accurate to 0.01 gram is standard equipment. The working parts

should be enclosed in a glass case and the pans protected with a

hinged glass cover or hood for increased accuracy in weighing.

A chainomatic analytical balance with notched beam, or a keyboardtype balance, with sensitivity of 0.05 milligram is required. Numerous balances are satisfactory. A magnetic damping device will reduce

the time required for weighing. Large laboratories will probably find

it economical to use one of the new type semiautomatic balances, such

as the "gram-atic" balance, even though they are very expensive.

To keep scales and balances in proper operating condition, they

should be: (1) Placed on solid tables (preferably stone-top tables)

which are not subject to vibration; (2) checked at the beginning of

each series of use to see that they are in balance; and (3) checked

regularly (about once a year) by a factory representative or some

other person completely familiar with their construction and use.

SEED CONTAINERS

Several kinds of seed containers should be readily available to the

analyst. These include shell vials with cork stoppers, Petri dishes,

50 cm. in diameter and 10 cm. high, sets of aluminum dishes which

nest together when stacked, gelatin capsules, and envelopes of assorted

sizes.

SAMPLE PANS

Sample pans are of different sizes but all should be tapered at one

end to serve as a spout when pouring the seed. They should have no

sharp angles, rough surfaces, or cracks in which small seeds may get

lodged.

SIEVES

Each laboratory should have at least one set of dodder sieves, consisting of 10 to 12 sieves with diameter of the holes ranging from 0.5

mm. to 3.5 mm., and additional sieves with round holes as well as rectangular and oval slots. The sizes of openings should be graduated at

close intervals and designed for the kinds of seeds tested. The bottom

should be of single piece construction and the angle made by junction

of the bottom and sides should be rounded out to prevent the lodging

of seeds. Dodder sieves are illustrated in figure 11 C and D,

DIAPHANOSCOPE

So far as is known there is no commercial firm in the United States

that manufactures a diaphanoscope. The principle of the diaphanoscope makes use of a beam of light directed obliquely upward through

a small hole in the top of a workboard or similar base. Outside light

should be excluded or reduced considerably for best results. A satisfactory diaphanoscope can be constructed as follows: Use an ordinary workboard 4 to 6 inches high and through its top bore a ll^-

inch hole, centrally located from end to end and 2 inches from the front

side. Mount a concave mirror below and to one side of the opening so

it will receive light from the direction of the back of the board and

reflect it obliquely through the small hole in the top of the workboard,
TESTING AGRICULTURAL AND VEGETABLE SEEDS 15

away from the worker's eyes. Cut a slot in the rear of the workboard

to allow light to enter. A microscope lamp placed on the table behind

the workboard with its beam directed against the mirror will provide

the necessary illumination. If desirable a reading glass can be used

as a condenser by placing it between the lamp and mirror.

In lieu of the assembly just described, the lamp can be detached from

its base and mounted below the workboard so the direct beam will pass

obliquely through the hole in the top of the workboard. If this mounting^ is used, the mirror is not required but openings for ventilation

must be provided to prevent the accumulation of hot air below the

working surface.

The diaphanoscope may be placed in a dark corner or closet, or a

hood may be constructed which can be placed on the table and around

the diaphanoscope. The hood should be approximately 36 inches

long, 18 inches deep, and 28 inches high. It may be made of light

frame construction covered with heavy dark cloth, plywood, Masonite,

or similar material. A coat of black paint inside the hood will aid

in absorbing outside light.

SEED BLOWERS

The principal feature of seed blowers is a uniform flow of air of

desired pressure upward through a column with a valve arrangement

to regulate the magnitude of the pressure. At present there are three

designs of seed blowers commonly in use in the United States, as follows: (1) The Iowa air-blast seed separator; (2) the South Dakota

seed blower; and (3) the Ottawa seed blower. These blowers are

briefly described in alphabetical order.

Iowa air-hlast seed separator,—The Iowa blower (fig. 10) relies

upon a uniform speed motor with attached fan and a single compression area to maintain a uniform pressure. There are two interchangeable seed cups and metal blowing tubes, the smaller accommodating

grass samples up to 5 grams and the larger up to 10 grams in weight.

Near the top of the tube is an adjustable trap to act as a receptacle

for the light material. A screen-covered cap prevents loss of material

from the tube. A gate-type valve located below the seed cup is an

advantage in that the seed is not disturbed when the blower is operating with the valve turned to the closed position. A geared vernier

attachment to the valve assists in making fine adjustments but this

combination does not always give the desired degree of exactness of

pressure.

Although the plans of the Iowa blower do not provide for alternate

use of a glass-blowing tube the necessary accessories can be obtained

with little difficulty. The following items are required: Collar to

substitute for the seed cup, piece of bolting silk, rubber stopper for

1%-inch hole, ordinary glass-blowing tube, and a glass cylinder, open

at both ends and with a hole in its wall for the blowing tube (fig. 11

A and B.) The collar is made of brass and is similar in construction

to that of the regular seed cup with the following exceptions : (1) The

screen is omitted and (2) the inside diameter of the upper part of

the fitting must be 1% inches instead of 1%6 inches in diameter. A

hole 1 inch in diameter is cut in the rubber stopper so it will slide over

the end of the blowing tube. The bolting cloth is placed over the lower

end of the blowing tube and is held in place by the rubber stopper
16 AGRICULTURE HANDBOOK XO. 30, U. S. DEPT. OF AGRICULTURE

which is slipped over the end of the tube. The seed is pUiced in the

open end of the tube and is allowed to fall upon the screen of bolting

cloth. The tube is held in place by inserting the rubber stopper in

the collar. Otherwise, the assembly is the same as described for the

Ottawa blower.

The Ottawa seed hlotoer.—In the Ottawa blower (figure 12) there

is a metal box containing an air impeller or fan, a low-pressure space,

and a high-pressure space. The impeller is operated by a uniform

speed motor. The seed cup and blowing tube are mounted over the

high-pressure area. The metal seed cup, with screen bottom, supports

FiGXiRE 10.—Iowa air-blast seed separator : A. View of entire unit ; B, construction

details of valve with vernier scale, seed cup, blowing tubes, and caps.

the glass-blowing tube whicii leads to a glass cylinder designed to retain the light material. Air pressure in the system is controlled by a

sliding gate operated by a closely threaded worm-gear adjustment.

There is a manometer which is used for establishing the settings at

which seeds are to be blown. For less exacting work the calibrations

for the gate opening may be used. The Ottawa blower is designed

specifically for small-seeded grasses and will not efficiently accommodate samples larger than 5 grams. The combination of uniform

speed motor, 2 pressure areas, fine adjustment of gate opening, and

manometer makes a very accurate machine.

South Dakota Mower.—In the South Dakota and Iowa blowers

uniform-speed motoi-s and blowers made by the same manufacturer
TESTING AGRICULTURAL AND VEGETABLE SEEDS 17

are used. The important features of the South Dakota blower are as

follows: (1) It has a small separating column for grasses that will

handle samples up to 5 grams of chaffy seeds and 10 grams of nonchaffy seeds and a larger column that will handle a 50- to 100-gram

sample of vegetable, cereal, sorghum, and vetch seeds; (2) the separating columns are made of a transparent plastic which enables the

analyst to see the movement of seed during the blowing operation ;

-^

U i '

I-M -

FIGURE 11.—A, Construction details of glass-blowing tube ; B, glass cylinder with

1%-inch hole tlirough which the short end of the blowing tube is inserted ;

C, and D, dodder sieves.

and (3) the valve is approximately one-half a disc, located at the top

of the blowing tube, adjustable by circular motion. Of the three seed

blowers described, this is the only one that will handle samples of

more than 5 or 10 grams in weight (fig. 13). Three models are

available.

It will be observed that each of the three seed blowers described

herein employs a uniform speed motor and fan. Since line voltages

are subject to considerable fluctuation, it is recommended that a

constant voltage transformer be used with each.
18 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FiQTJKE 12.—Ottawa seed blower : A, Gteneral view ; B, gate and gate adjustment ;

G, manometer with magnifier and liquid reservoir.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 19

»t^

B

FIGURE 13.—South Dakota seed blower : A, View of entire unit with large blowing

column ; B, sectional view of large blowing column ; a, top screen and air

control or valve; ft, column; c, seed cup and bottom screen; (1) valve; (2)

top screen; (4) seed traps; (3, 5, 6) seeds of different specific gravity being

blown.
20 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

SEED HERBARIUM

A good seed herbarium is essential to any modern seed-testing

laboratory. Herbariums are not bought but are the result of years of

effort on the part of interested, patient, and painstaking workers.

The chief methods of obtaining seeds for herbariums are through

collections from plants in the field or seed samples received in the

laboratory, exchange, and gifts. Some seed-testing laboratories, as

Avell as departments of botany and agronomy in State agricultural

colleges, are in a position to assist in building up herbariums. The

importance of correct identification and labeling of all samples which

go into the herbarium cannot be overemphasized. Many samples of

the same species or variety should be included to give the range of

variation that may be expected. Several kinds of seed containers have

been suggested for herbarium use but none seem as convenient as glass

shell vials. Two types of trays for holding the vials are in use in the

Federal laboratories. One is a strong cardboard box with lid, covered

with durable, impregnated black cloth. These trays are made in %-,

1-, and 114-inch depths, the other dimensions being 171/2 by 11% inches.

The more shallow trays are divided by cardboard partitions into 100

spaces, and the larger into ?)0 or 48 spaces, the number depending on

the kinds of seed for which they are intended. These trays can be

labeled, stacked, and stored in a cabinet. A cabinet with closely spaced

shelves to accommodate not more than 2 or 3 trays is preferred.

The other type of container consists of steel, blank sections designed

for maps. Each section consists of either 6 or 18 drawers, each 16 by

9I/2 by 11/2 inches. In botli sections the drawers are arranged 6 deep

and in the larger section they are 3 drawers wide, the over-all dimensions being 33 inches in length, 13 inches in height, and 17 inches in

depth. Cardboard separators to fit into the drawers can be made to

meet the needs of the individual laboratories. These can be made by

hand for a small herbarium but paper-box manufacturers will make

them when the quantity justifies.

LAMPS

Every effort should be made to provide maximum window space

with northern exposure for the analysts who test seeds for purity.

Southern and western exposure must be avoided. Many laboratories

are not so fortunate as to have sufficient daylight space and must resort

to electric lights. Also, daylight is totally inadequate at times, even

with a maximum amount of window space and the most desirable exposure. Of the different kinds of lamps and tubes commonly used,

daylight-type fluorescent lamps appear to be the closest approach to

natural daylight. If natural daylight is weak, overhead ¡fluorescent

lamps should be provided. For close work in purity testing, individual desk lamps equipped with daylight type tubes are also required. Only multiple tube lamps in which the tubes are synchronized

to minimize the stroboscopic effect or "flicker" should be used. The

so-called floating fixtures, consisting of movable arms with swivel and

hinged joints, that are held to desired positions by a spring undei'

tension have iDcen found satisfactory.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 21

EQUIPMENT FOR GERMINATION TESTING

FORCEPS

Forceps for removing seedlings should neither be blunt nor as sharppointed as described for purity testing. Blunt forceps are awkward

to use when removing small seedlings, and fine-pointed forceps are

dangerous owing to the fact they must be handled with rapidity and

they pierce the paper substratum easily.

MAGNIFIERS AND MICROSCOPE

Hand lens as described under equipment for purity testing are required by the germination analyst. A good reading glass mounted on

a stand is desirable for counting very small seedlings. A stereoscopic

microscope and compound microscope should be available, if samples

are to be examined for fungi.

SAMPLE PANS

Sample pans similar to those described under equipment for purity

testing, except that the pouring spout should be very narrow, are

necessary for the germination laboratory.

GLASSWARE

The germination laboratory should keep on hand a supply of assorted sizes of beakers, flasks, bottles for chemical solutions, graduate

cylinders, burettes, distilled-water bottles, and Petri culture dishes.

Since Petri dishes are used for seeds that require light exposure during germination, the number needed will depend upon the requirements of each laboratory. Petri dishes, 100 mm. in diameter, are

generally used for seeds the size of Lactuca and Poa but 120-mm.

dishes are preferable for Dactylis and Bromus. However, it has been

impossible to obtain this larger sized dish in recent years. Bell jars

or similar covers are necessary for covering seed on the workboard

when the analyst finds it necessary to leave an unfinished sample.

Plastic cake covers and plastic bell domes are preferred as they are not

so heavy to handle as glass bell jars and are resistant to breakage.

SOIL AND SAND BOXES

Different kinds of containers have been used to hold soil and sand in

germination testing. The most commonly used containers are paraffined cardboard boxes, sizes 4i^ by 41/2 by 1% inches and 8% by 81/2

by 1% inches. The boxes are usually purchased unassembled but

creased and perforated. To assemble, the sides are folded upward,

the corners folded over, along the creases, and fastened by inserting

a staple with an ordinary stapling device. The advantages of using

these boxes lie in the fact that they can be discarded after each use.

Thus, problems incident to storage and cleaning are eliminated.

The sides of the large boxes tend to sag when filled, thus allowing

the soil to dry along the edges. This can be eliminated by having

metal bands constructed with inside dimensions to fit over the cardboard boxes. The bands should be 1% to 2 inches wide and made of

aluminum or other noncorrosive metal. They may be stored and

used repeatedly.

Recently plastic boxes have been introduced as soil and »and containers. A popular size now on the market is 4% by 414 by li^
22 AGRICULTURE HANDBOÔlC KO. 30, U. S. DEPT. OF AGRICULTURE

inches. When ordering plastic boxes one should make sure the size

and shape conform to the shape and dimensions of the appropriate

counting head.

SPRINKLING DEVICES

Florists' rubber bulbs which hold approximately 250 to 300 cc, with

perforated nozzle, are excellent for remoistening most types of substrata in laboratory tests. However, it is preferable to use a medicine

dropper with rubber bulb when remoistening substrata in Petri dishes

or other small closed containers. Otherwise, the tests can easily be

flooded.

SOIL AND SAND STERILIZERS

Itis essential that occasional sand or soil tests be made in the laboratory, or greenhouse if available, chiefly as a guide in evaluating tests

made on artificial substrata. Sand or soil used for this purpose should

always be relatively sterile to devitalize any weed or other seeds and

fungi which may be present. Some laboratories located at experiment

stations or near commercial greenhouses have found it possible to make

arrangements whereby they can obtain soil or sand already sterilized.

Some laboratories sterilize their sand in an ordinary gas-heated laboratory oven. The sand is placed in shallow trays or pans and heated

for approximately 2 hours.

Some of the large companies that manufacture electrical appliances

have electrical heating units for sale and provide plans and specifications for electric soil sterilizers. For example, one firm has plans

for a l^ cubic yard sterilizer that requires 4 electrical units wired in

parallel on a 110-volt circuit. The plans may be modified for a

smaller box by using 1,2, or 3 heating units.

SEED COUNTERS

Counting devices are now regarded as standard equipment in seedtesting laboratories. There are two types of seed counters: (1)

Counting boards ; and (2) vacuum counters.

Counting hoards,—Counting boards are frequently used for large

seeds such as corn, beans, and peas. A typical counting board has a

stationary bottom, approximately the size of the substratum to be

used, perforated with ÖO or 100 holes the general shape and size of

the seeds to be counted (fig. 14). Below the perforated base is a thin

solid board which serves as a false bottom and can be moved forward

and backward. In operation, the counting board is placed over the

substratum, the seed scattered over the board, and the excess seed removed by tilting the board slightly. After checking to see that there

is only one seed per hole the movable bottom is withdrawn and the

seeds fall in place upon the substratum.

Vacuum eou/nter.—^There are three essential parts to a vacuum

counting device: (1) Vacuum system including lines; (2) counting

plates or heads; and (3) valve. A laboratory which expects to count

corn and large-seeded beans by vacuum will need a system that will

support from 20 to 27 inches of mercury at the point where the counting head is attached. The capacity for suction must be great enough

to hold the seeds with leakage caused by their irregular surfaces. The

hose, valve, line, and all connections should have openings of sufficient size so as not to restrict the flow of air. For the counting of
TESTING AGRICULTURAL AND VEGETABLE SEEDS 23

large seeds no constriction should be less than % inch. A capacity

of 5 to 8 cubic feet per iTiinute appears to be sufficient for clovers

whereas larger seeds such as corn and beans may require a capacity

of 15 to 18 cubic feet p^v minute.

The vacuum counters used in most laboratories are direct acting,

that is, the vacuum at the counting liead is created only when the

vacuum pump is in operation. This requires that the operator switch

FiGUKE 14.—Counting board for large seeds.

the motor on and off with each use. On the other hand, a few laboratories have a tank between the counting head and pump. In the latter

case the piunp operates automatically as the partial vacuum in the

tank is reduced. The following precautions should be kept in mind

when selecting a vacuum unit: (1) Avoid noise in the laboratory by

selecting a pump that is relatively noiseless or else locate the pump in

an unused adjacent room; (2) avoid pumps whicli expel oil through

the exhaust. A vacuum counter is shown in figure 15.
24 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

FIGURE 15.—Vacuum seed-counting unit : A, Unit enclosed in sound-insulated

cabinet; B, interior view showing electric motor, pump, Alter, and gage.

Seed-couiitiiig heads uve mude in sciuare, rectiiiigular, or disc shapes

to fit the stibstratuin. Tlie liead has front and back faces between

which there is a cavity for air passage. It is a completely airtight

system except for the hole in the back plate for attachment to the

valve and the holes for seeds in the front face. The opening for

attachment to the vaciunn svstem should be a standard female fitting
TESTING AGRICULTURAL AND VEGETABLE SEEDS 25

for a %-inch nipple. Tlie size of head and the number and arrange-!

ment of holes for the seeds will be determined by the size of seed to

be counted and the dimensions of the seed bed. Typical examples

of counter heads used in the Federal laboratories are indicated in

table 1. Counting heads may be made of brass, aluminum, or other

noncorrosive metals and plastic. Plastic is preferred for the large

counter heads (that is, larger than approximately 50 square inches)

because of its lighter weight.

The valve should: (1) Have a standard %-inch female fitting for

the end or side connecting to the counter plate, and either a tapered

fitting for rubber hose on the other end (fig. 16) or a %-inch female

fitting for connection to flexible tubing (fig. 15) ; (2) be easily adjusted

to different settings between "on-' and "off'' positions; (3) remain in

fixed position at any point of adjustment; and (4) be free of leakage

at all times. Adjustment to different positions is necessary as the

tenacity with which seeds cling to the openings determines, to a large

extent, the ease and success of counting small and irregularly shaped

seeds. Some vacuum-counting heads are illustrated in figure 16.

TABLE 1.—Eocamples of vaeuicin-counting heads

Kind of seed Size of

head

Holes in

head

Diameter

of holes

Corn, beans, peas

Do

Cereals

Beets, vetch, field peas

Clovers, lespedeza

Ryegrass, brome, orchard grass, fescuc_

Poa, Agrostis, Phleum

Inches

6x9

9K X 12

5x6

5x6

4% X 4/4

1 á}i diam,

2 3>i diam.

Number

25

50

50

100

100

100

100

Inch

0. 050

.050

.040

. 035

. 016

. 016

.010

1 Circular head for 120-mm. Petri dishes.

8 Circular head for 100-mm. Petri dishes.

THERMOMETERS

The laboratory should have each germination chamber equipped

with at least one thermometer and an additional supply should be

kept on hand for replacements and special checking. Ordinary chemical thermometers calibrated to the Centigrade scale and with clearly

legible numbers are preferred. A few laboratories have self-recording thermometers or thermographs. These are excellent as they provide a record of temperatures for the entire period covered. However,

because of the high cost of these instruments most laboratories find

it beyond their budgets to install a thermograph on or within each

chamber. They are to be recommended for use in germination rooms

or unusually large germination chambers. Ordinarily, it is sufficient

to check the temperature of small chambers which are in good operating condition, once or twice daily.

GERMINATORS

Water-cooled germinator.—The kind of germinator is not particularly important so long as the conditions ©f temperature and mois-
26 AGRICULTURE HANDBOOK; NO. 3 0, Ü. S. DEÎ>Ï. OF AGRICULTURE

ture are met. The type of germinator most commonly used in tlie

United States consists of a small chamber with provision for cooling

and heating to insure adequate temperature control and which has

a shallow layer of water at the bottom to maintain high humidity.

A chamber of approximately 9 cubic feet capacity witli inside dimenB

FIGURE 16.—-Vacumn counter heads : A, Rectangular head for 50 seeds the size

of wheat; B, different shapes and sizes of counter heads.

sions of 26 inches wide, 2-Í inches deep, and 27 inches high will accommodate 13 trays I8I/2 by IQYz inches spaced at 2-inch intervals and

will provide ample additional space between trays and around the

edges for the movement of air (fig. 17).

In most parts of the country it is necessary to have means of refrigeration during a part or all of the year. It is very difficult to main-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 27

tain high humidity in the air when the temperature is reduced below

approximately 20° C. In fact, it is not unusual to find serious drying

of the substrata at 10°. Perhaps the most reliable germination chamber in use is the type which is cooled by refrigerated water passing

through coils that line the inside of the chamber or through a water

FIGURE 17.-—Four-unit water-cooled germluator.

on top of germinating units. The cooling

chamber.

The refrigerator unit is located

coils can be seen in tlie open

jacket between the walls of the chamber. There are various types of

electric heaters that can be used inside the chamber, either submerged

in water or suspended in the air. The chambers may be constructed

of 24-gage noncorrosive metal, or if cooling coils are used they may be

lined with stone.

957110—32——3
28 AQUICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

In the water-cooled germinator, valves are adjusted to allow a flow

o,f water that will cool the chamber slightly below the desired temperature. The heater, which is hooked up with a temperature regulator, holds the temperature at the preestablished setting. The

water-cooled germinator doe^ not lend itself to a rapid reduction in

temperature when used as an iilternating temperature chamber. For

seeds requiring an alternating temperature, two constant temperature

chambers are used and the trays of test material are usually transferred from one chamber to another as required.

FiGUKE 18.—Foui-uuit air-coületl germinator. The uir-cuiiditioiiing boxes are

immediately t)eliind the electrical switches which appear as blaels squares near

the door hinges.

Air-conditioned germinator.—A germination cabinet has recently

been designed which is heated and cooled on the principle of air

conditioning (fig. 18). In addition to the seed chamber there is

a small air-conditioning box, the two being joined by openings at

the top and bottom of the germination chamber. Air is either

heated at the top of the box as it is forced downward past heating coils

or is cooled as it passes over a curtain of cool water near the bottom

of the box. The air is circulated throughout the air-conditioning box

and germination chamber by a small fan which operates when either

the heating or cooling system is in operation. The entire system,

including alternation of temperatura at preestablished times, is

automatic.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 29

The air is humidified by a constant spray of mistin the air-conditioning box. Temperature can be increased from 20° to 30]^ C. within

20 minutes and reversed within 30 minutes. The principal advantages of the air-conditioned germinator are: (1) Space is conserved

as the test material remains in the same germinator both day and

night; (2) no manual work is required in transferring the test material; (3) the temperature is alternated at times when the laboratory

staff may not be working. The following disadvantages have been

observed: (1) The electrical system is rather complex and either one

of several devices (such as relays, heaters, fans, solenoids) may become inoperative and require the services of an electrician; and (2)

the spray jets become clogged rather easily if the water contains

sediment, calcium, or iron, and require frequent attention, or else the

test material suffers from loss of moisture.

Room-type germinator.—This type of germinator, which is sometimes referred to as a walk-in germinator, is in use in several of the

larger laboratories. Koom germinators are usually from 6^/^ to 7

feet high and occupy sufficient space to allow a row of trays along

each Avail with passage way between them. Like the germination

chambers previously described, the inner walls, floor, and ceiling

should be made of moistureproof, noncorrosive materials.

The problems incident to maintaining uniform temperatures and

high humidity of the atmosphere increase as the capacity of the germinator is increased. Provision must be made to avoid stratification of

temperature, differential of air currents, and areas of low^ humidity.

Since the relative humidity in germination rooms is less than 100

percent the amount of drying of the substrata is materially affected

by the amount of moist substrata or number of tests in the room. In

other words, there may be no appreciable loss of moisture if the

room is used to capacity but if only a few tests are being carried there

may be serious drying of the substrata.

The essential requirements of a germination room are as follows:

(1) Room, adjacent to regular germination laboratory, 6I/2 to 7 feet

high, 61/2 to 8 feet w^ide, and of desired length, constructed of waterresistant walls and ceiling and of waterproof floor; (2) automatically

controlled heating system that will meet the requirements for the

desired constant or alternating temperatures; (3) refrigeration system, preferably cool air, which will maintain the lowest temperature

needed; (4) reliable spray system to maintain high atmospheric

humidity; (5) fans to slowly circulate the warm and cool air; and

(6) cold-cathode fluoresuent lights for a section of the room where

light-sensitive seeds may be tested or special soil or sand tests may

be made.

Daylight gerinination chamher.—One or more daylight germinators

are required for grass and some vegetable seeds. The illumination

should provide from 75 to 150 foot-candles of light on the different

areas where seeds are to be placed. This may be provided by either

natural daylight, fluorescent lights, or both. Because of the temperature effects a daylight germinator should not be placed in windows

where the direct sunlight will fall upon it. When artificial light is

used to supplement daylight, special provision must be made to keep

the temperature down. In the Northern States the temperature can

be kept to 30° C. when 4- or 5-foot fluorescent tubes are used if the

tubes are placed from 10 to 15 inches from the wall of the chamber.
30 AGRICULTURE HANDBOOK NO. 3U, U. S. DEPT. OF AGRICULTURE

If the laboratory arrangement requires closer spacing of the tubes,

provision must be made for cooling, particularly in the warmer sections of the country. To avoid stratification of temperature it is advisable to introduce cold water at the inside, top, and front of the

germinator, allow it to run over a sloping glass retainer to tlie rear

wall and trickle down the latter into a reservoir at the bottom. The

water may be either drained away as waste or returned to the

refrigerator for continuous use.

FIGURE 19.—Custom-built daylight germinator. Natural liglit is supplemented

by the fluorescent tubes at the back and ends of the chamber. This unit

consists of three sections, but without partitions.

In the germinator illustrated in figure 19, 4-foot fluorescent tubes

are placed 3 inches from tlie glass wall of the chamber. Refrigerated

water is released as described above and flows into a water reservoir

in the bottom of the chamber with overflow pipe leading to the drain.

An immersion-type heating coil is located in the water reservoir. The

heater is controlled by a temperature regulator and the flow of cool

water is regulated by a solenoid valve which in turn is controlled by

another temjjerature regulator. The chamber illustrated in figure

20 is a commercial model which operates very much on the same

principle as the chamber just described. In the commercial model,

the water is returned to the cooling system for continuous use.

GERMINATION TRAYS

Standard trays.—Germination trays are usually made of heavy

metal gauge with interspaces 14- to %-inch square. Tlie frame must
TESTING AGRICULTURAL AND VEGETABLE SEEDS 31

be of solid construction and the wire gauze which supx3orts tlie substrata must be firmly fastened to the frame.

If the edge of the frame is bent upward for 14 to ^/^ inch to form a

90° angle with the ñat surface of the tray, it will serve as a guard to

keep the seeds from sliding off when the tests are being handled. In

lieu of the above construction, sheet metal may be perforated to form

FiGUKE 20.—Commercial model daylight germiuator. The refrigeration unit is

at tlie bottom of the chamber.

suitable trays (fig. 21). The holes should be approximately i/> inch in

diameter and within i^ inch of each other. The edges can be turned

upward and welded to serve as guards, as just described. Copper,

aluminum, magnesium alloys, or monel may be safely used in constructing trays. Galvanized steel or any other metal which may

contain soluble zinc salts should not be used. It has been shown that

the zinc from galvanized trays will produce toxic effects upon certain

kinds of seedlings.
32 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF ACiRlCULTURE

Trays for upright towel tests.—The following type of holder for

upright towel tests has been found satisfactory. I3y using 1-inch

strips of 20 gage copper, aluminum, or other suitable metal, a frame in

the form of an ordinary box is made and attached to a bottom of the

same construction as the standard tray, except for size. When complete th« holder consists of 4 corner posts, top, center, and bottoiii strips

or rails along the ends and sides as shown in figure 22. Two sizes are

made as follows: (1) 9 by ITi/a by 8 inches; and (2) 91/2 by 18 by 8

ttW ^m

FIGURE 21.—Standard germination tray constructed of perforated No. 10 gage

stainless steel.

inches. The two sizes offer the following advantages: (1) Two of

these holders will fit on an 181/2- by 19y2-inch germination tray; (2)

the analyst has to handle only one-half the load of a full tray ; and (3)

M'hen not in use the smaller holder nests inside the larger, thus economizing on storage space.

ULTRAVIOLET LAMP

An ultraviolet lamp is required in laboratories testing the roots of

ryegrass (Lolium) for fluorescence. The requirements of the lamp or

unit are as follows: (1) Kadiation of ultraviolet waves with a maxi-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 33

mum peak at approximately 3650 AU (Angstrom units) ; (2) radiation of sufficient intensity to activate the weak fluorescent lines; (3)

filtering out of most visible light; and (4) exclusion of daylight from

the working area.

The kind of ultraviolet lamp or unit which a laboratory should

install or have on hand will depend, to a great extent, on the number of

samples to be tested during the course of a year. A good lamp permanently mounted in a dark room, closet, or chamber is desiraole in

laboratories that test relatively large numbers of samples. A lamp

that employs an EH 4 mercury lamp and Corning 5840 Red Ultra or

5874 Red Purple Ultra filter has been found to be excellent. Certain

small portable units are satisfactory if only an occasional sample is to

be tested. These usually consist of a metal or plastic frame, a metal

KiGuiiE 22.—Hack or container for uiiright roll towel tests.

reflector, and one or two black, fluorescent, mercury-filled tubes. Of

several models tested the one found to be most satisfactory had two

5-inch tubes, plastic frame with handle, and the starting ballast located

at the end of the electrical coi'd which plugs into the wall receptacle.

The so-called "black lights" which resemble incandescent bulbs in

shape should not be used as they do not activate some of the weak

fluorescent lines.

FLUORESCENT-LIGHT GRIDS

The fluorescent-light grid illustrated in figure 23 is placed horizontally in the germination chamber to provide uniform lighting over

the entire area where the tests are located. The outside dimensions

are the same as the dimensions of the germination trays so the grids

may rest upon the tray slides. The grids are mounted on every third

tray slide, thus permitting the placement of two trays of test material

under each grid. At midday the positions of the two trays are re-
>

o

a

o

d

d

O

w

o

o

w

o

Ö

Tí

O

SOM

d

d

FiGUKE 24.—Beets (ßeia vulgaris). Normal and abnormal seedlings from 14-day tests between blotters
TESTING AGRICULTURAL AND VEGETABLE SEEDS 35

amperes for best operation. Four grids may be operated by a 9,000-

secondary-voltage transformer but usually it is better to operate

two grids on one 5,000-volt transformer and the other two grids on

a similar transformer. This permits the switching off of two grids at

any time they are not needed. All connections must be secure and all

high-voltage wires that are located inside the chamber should be

covered with glass insulators. The transformers should be located

outside the germination chamber. As a precaution it is advisable to

place in the door casing a switch which will break the primary voltage

leading to the transformer when the door is opened.

Stratification of temperature can be overcome by bending copper

tubing of i/^-inch outside diameter into grids of similar shape and

dimensions as those of the fluorescent light grid. A metal grid is

mounted immediately above each light grid and connected to a source

of refrigerated water. The free end of each metal grid is continued

to one side near the bottom of the chamber and terminates in a needle

valve which is used for adjusting the now of water. The valves are

adjusted to permit more water to pass through the upper cooling grid

than the one next below. Proper temperature control of the entire

chamber can be accomplished by either of two methods: (1) Adjust

the flow of cold water so it will reduce the temperature slightly below

that desired. Raise the temperature up to the degree desired

through the use of electric heaters wired in series with a thermostat.

(2) Place a solenoid valve in the incoming water line and wire this

in series with a thermostat set at the desired temperature. The valve

will cut off the supply of cold water when the desired temperature

is reached and will open the valve when the chamber becomes too

warm. A pool of cool water in the bottom of the chamber is undesirable as it interferes with proper adjustment of temperature.

BEET SEED WASHER

Occasional samples of the different varieties of Beta vulgaris seed

require washing with running water from 2 to 4 hours to remove the

toxic principles causing darkening of the radicles. This washing may

be done by placing the seeds loosely in cheesecloth bags and the bags

in beakers into which water is running. If very many samples are

to be tested a device to hold the seeds, while washing, is recommended.

Baskets 1^^ by 1% inches in cross section and 2 inches high made of

20 by 6 mesh copper gauze make good seed holders. The baskets may

be placed in a stream of running water.

If uniform washing is desired this can be accomplished by constructing a pan having walls 2% inches high with drain spout % inch

from the top and a false bottom soldered to the walls 1 inch from the

bottom. The false bottom has a %2-inch hole beneath each basket.

When the hose is attached and the faucet is opened water enters the

compartment between the bottom and false bottom and squirts up

through each hole agitating the seeds while washing them. The size

of the pan is determined by the number of baskets to be used.

GREENHOUSE

It is sometimes desirable to conduct germination tests on questionable samples over a sufficient period of time to observe development

beyond the seedling stage. Gryçenhouse space with provision for con-
36 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

trol of temperature within the range suitable for the kind of seed to

be tested, and other facilities, should be available for this purpose.

The greenhouse should be locaied in close proximity to the seed-testing

laboratory.

FILING CABINETS

Among the problems of retaining file samples for future reference

is that of protecting them from rodents. Some laboratories use allmetal boxes which may be stacked or placed on shelves built for that

purpose whereas others store official samples in glass fruit jars. The

Federal laboratories have found sections of close-fitting drawers to

be convenient for this purpose and to protect the samples from rodents.

Each section is composed of 16 drawers, 4 across and 4 down. The

front and back of the drawers, and the frame are of oak while the

sides and bottom of the drawers are of galvanized metal. Each draw^er

is 12 inches wide, 24 inches deep, and 6 inches high.
OBTAINING THE SEED SAMPLE

SAMPLING THE SEED LOT

OBJECTIVE

The basic objective in sampling a lot of seed is to draw a portion

which is representative of the entire lot. Such a sample is the basis

for analyses to determine the purity, germination, noxious-weed seed

content, origin, variety, composition, and other quality factors. The

results of these tests, of course, cannot be more accurate than the

sample submitted.

USE OF SAMPLING INSTRUMENTS

There are numerous instruments designed for drawing a sample

from seed in bags or in bulk in bins. These are described in detail in

the section on equipment. The short thief trier or sticker type of

instrument is widely used, presumably because of the convenience in

using and carrying it. However, it is generally agreed that an accurate sample cannot be drawn with this type of instrument. Regardless of the number of places a single bag of seed might be pierced only

the outer few inches of seed will be sampled, and no portions would be

obtained from the center of the bag.

The double-tubed sleeve-type triers are the most satisfactory of

the sampling devices in general use for sampling seed in bags. They

should be long enough to take seed from different locations in the

seed bag. Equal quantities may be taken from each seed bag probed

with the sleeve-type trier, whereas the amount of seed drawn from

each bag with a thief trier is purely a matter of personal choice.

HOW TO DRAW THE SAMPLE

The theory of sampling assumes that a seed lot is made up of homogenous material and that a composite sample drawn in accordance

with established procedures will represent a particular lot of seed.

This sample should be made up of equal portions taken from evenly

distributed parts of the quantity sampled. In quantities of five bags

or less, each bag should be sampled and in quantities of more than

five bags every fifth bag, but not less than five, should be sampled.

If the sleeve-type probe is employed, seed bags should be in a horizontal position to insure that as the tube of the trier is opened, seed

will drop in along the entire length of the bag. Perhaps the best

sample coverage comes from following a diagonal path through the

seed bag to an opposite corner. The probe should be inserted with

the slots facing downward so that as it is inverted, or placed upright

for collecting the sample any seeds "dragged along" by the cross ribs

will be dislodged and will not be added to the portion drawn. Sampling a bag of seed standing upright results in obtaining unequal portions from various parts of the bag.

Each probeful of seed from each bag sampled should be examined

before adding it to the composite sample in order to determine that
38 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

the seed being sampled is uniform in quality. Uniformity of color

and general weed-seed content should be noted and any probefuls

deviating from previously drawn portions should not be added to the

composite sample. The bags of seed in question should be appropriately identified, set aside, and cannot be considered a part of the lot

being sampled. If this procedure is followed, there will be little

danger of mixing seed from improperly segregated seed lots.

Certain chaiEy grass seeds and nonfree-flowing seeds such as Bromnis

spp., Andropogon spp., or Paspalwn spp. which may not be easily

sampled with a probe can be sampled by hand. Hand sampling necessitates opening the seed bag, thrusting the hand to different parts

of the bag, and removing small portions of seed from the bottom,

center, and top.

SIZE OF SAMPLES

Too often laboratories receive samples of insufficient size for testing.

The inspector or sampler should make every effort to obtain samples

of at least the minimum quantities set out in the rules. An inspector

or sampler may hesitate to draw a large quantity of seed having a

high retail value but it is necessary to submit samples of at least

the size stated in order to provide adequate seed for standard tests,

and retests if necessary.

CAUTIONS TO BE OBSERVED IN SAMPLING

Whether the seed sample is drawn by a seedsman or farmer for his

own guidance or by an official seed inspector, there are general cautions

to be observed in order to obtain an accurate sample. The sampler

must first determine that all seed bags being sampled are identified

as belonging to a single lot, either by a label or stencil mark on the

bag. He must sample the prescribed number of bags for the size of

lot at hand. If, in sampling a large lot, more seed is obtained than is

feasible to forward to a laboratory, care must be exercised in reducing the quantity for shipment. As a mechanical divider is usually not

available, the sample reduction might best be done by placing the

entire quantity on a sheet of paper or canvas, thoroughly mixing the

seed by hand and halving the sample until the desired quantity is

obtained. The value of this procedure becomes more obvious in instances where official inspectors are required to leave duplicate samples

with the dealer. A haphazard splitting of the sample could not be

expected to produce two similar portions.

Damage to seed bags is of prime consideration to seed inspectors

as well as to merchants. The thief trier does little damage to cotton

bags, but its accuracy in drawing a representative sample is questionable. The longer probes can safely be thrust into burlap bags which

are easily "scratched over." A few stitches at one of the top corners

of machine-sewed cotton bags can be broken and then this break can

be closed with a hand-stapling device, after the contents of the bag

have been sampled.

SAMPLING RECORD

It is essential that the inspector keep accurate records concerning

the history and manner of sampling each lot of seed forwarded for

official tests. Each sample should be clearly marked so as to be easily

identified. Any sample known to have been treated with a poisonous

fungicide should be so identified by the inspector or sampler so the
TESTING AGRICULTURAL AND VEGETABLE SEEDS 39

analyst may be warned of that fact. The sample envelope should be

sealed to prevent any contamination and if forwarded by mail the

samples should be packaged to arrive in an undamaged condition.

REDUCING THE SAMPLE IN THE LABORATORY

OBJECTIVE

Seed samples received by a laboratory generally need to be reduced

to a working sample of standard weight. These weights are tabulated

in the rules, for the various kinds of seeds, and have been determined

to provide an adequate number of seeds for purity analyses and for

noxious-weed seed determinations. Since the working sample is such

a very small portion of a large bulk of seed, the value of obtaining

a valid original sample cannot be overstressed. Whenever possible,

the sample should be divided by a mechanical divider or sampler. In

cases where a mechanical divider is not available for reducing the

sample other methods described herein may be followed.

USE OF MECHANICAL DIVIDERS

The use of mechanical dividers eliminates the personal element in

reducing the bulk to a working sample. All mechanical dividers in

common use, except the Ottawa divider, are designed to split the

sample into two approximately equal parts. The working sample is

obtained by repeatedly dividing the sample until a quantity of approximately that stated in the rules is obtained. It is frequently

necessary to run the "unused" part of the sample through a series of

divisions to get a few seeds to bring the sample up to the necessary

weight.

The Ottawa divider is designed to divide samples into: (1) Two

parts of equal weight; and (2) two parts of unequal weight. To

divide into two parts of equal weight the seed is allowed to run gently

into the divider without any further adjustment. If the sample is of

such a size that even divisions will not give the desired weight of

working sample, an unequal division is made to give two parts, one

of which can be reduced by even division to the desired weight. The

sainple is weighed and the closest weight that can be reduced to the

desired weight, by equal divisions, is determined by calculation. By

adding the necessary balance weights to one pan the excess seed falls

into this pan and the desired weight of seed into the other pan. The

working sample is then obtained by repeated equal divisions.

Any attempt on the part of the analyst to correct the sample size

by personally adding or removing seeds to obtain an even weight

defeats the objective of using a mechanical divider.

HALVING METHOD

The sample should be placed in a pile on a clean surface and after

thoroughly mixing by hand it may be successively halved by use of a

sharp-edged instrument until the required approximate weight is obtained. Although this method is included in the rules for seed testing

it is the least desirable of the methods discussed herein.

RANDOM CUPS METHOD

A series of small cups or thimbles of known capacity are arranged

on a tray or pan, in definite pattern, and the sample poured systemati-
40 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

cally over this. area. The working sample is obtained from randomly

selected thimbles or cups. The method may be modified by using

a tray, divided into an equal number of square compartments, every

alternate one of which has no bottom.

CARE OF SAMPLES

SAMPLES AWAITING TEST

The large number of seed samples ordinarily received by a laboratory during a testing season necessitates care in: (1) Retaining the

identity of each sample received; (2) avoiding damage by rodents

or insects; and (3) avoiding exposure to extreme variations in temperature and moisture. Seed samples received by a laboratory should

be unpacked as soon as possible and should be given a record number

so that they may be readily located and referred to when necessary.

Samples which cannot be tested soon after receipt should be stored

in a systematic manner to prevent their loss and to provide for more

efficient laboratory operation. If two or more samples have become

mixed due to accidental breaking of the seed containers, new samples

should be obtained.

Samples awaiting test or samples which have been tested and filed

for future reference should be given adequate protection against possible damage by rodents. This is particularly true if seed is stored

in attics or basements.

It is essential that samples infested with weevils, moths, or chalcid

flies be keptintact, preferably in sealed containers. The seed envelope,

if closed, will usually protect the sample during the routine period

it awaits test. Samples that upon arrival are so badly infested as to

be of little value or which show signs of recent insect activity should

be destroyed and additional samples should be obtained. A small

amount of paradichlorobenzene added to the seed envelope or other

closed container will kill the common insects which jnfest seeds.

Care should be exercised to insure that seed samples are not exposed

to extremes in temperature, or moisture, while awaiting tests. Only

samples that are received in the laboratory in airtight containers

should be tested for moisture content. The hard seed content of some

legume seeds has been known to increase when stored in a dry atmosphere. It appears a strong possibility that there may be a change in

hard seed content for certain legume seeds that are left in a laboratory

with a dry atmosphere for a few weeks.

Caution should be exercised not to expose seeds to fumes from some

of the more volatile herbicides as a few cases have been reported in

which abnormal seedlings were produced by accidental exposure to

fumes of some of these compounds.

SAMPLES FILED FOR FUTURE REFERENCE

Any sample that is filed may need to be tested for germinatioii at

some future date. Therefore, it is of utmost importance to itore

the samples under favorable environmental conditions. Either^high

temperature or high humidity may cause rapid loss of the viability

of seeds and a combination of both conditions is particularly bad;

whereas, storage in a cool dry environment is conducive to longevity

of seed and tends to reduce or eliminate insect activity which might
TESTING AGRICULTURAL AND VEGETABLE SEEDS 41

otherwise make infested samples valueless. It is advisable to place

approximately 14 teaspoonful of paradichlorobenzene flakes in samples suspected of being infested with insects. Samples should be filed

in rodentproof containers or cabinets. All seed-testing laboratories

should have ample space and facilities to provide the most favorable

storage conditions.

There is nothing in the rules for seed testing that will serve as a

guide in respect to the length of time file samples shall be retained.

However, the Rules and Regulations under the Federal Seed Act provide that records (including seed samples) pertaining to interstate

shipments of seed shall be kept for 3 years, except that the seed

sample may be discarded within a year after disposal of the seed lot

which it represents. It is not feasible to retain all samples for 2 to 3

years; however, no sample should be discarded within 12 to 15 months

after testing. Samples known to represent seed lots about which there

is official or civil action should be retained until the cases are terminated. Commercial analysts can frequently perform a service for their

patrons by arranging to retain their file samples. All file samples

should be of sufficient size to permit a noxious-weed seed examination

in accordance with the rules for seed testing.
PROCEDURES FOR DETERMINING PURITY

COMPOSITION

The object in making the purity analysis is to determine the identity

of the important kinds of seed present and the percentage by weight

of each component; namely, pure seed, other crop seed, weed seed,

and inert matter. Since the germination test is based on the pure

seed component it can readily be seen that the purity analysis and

germination test complement each other. Thus, the actual plantproducing power of the seed lot can be determined only when the

purity analysis and the germination test are considered together.

ACCOMMODATIONS

LABORATORY SPACE AND LIGHT

Testing seeds for purity is a meticulous, painstaking operation,

requiring constant use of the eyes. To avoid serious eyestrain the

purity-testing laboratory should be located as ideally as possible.

Large, single-paned windows extending to within approximately 30

inches from the floor and overlooking a wide expanse of green are

ideal. The first consideration in choosing a location for the puritytesting laboratory should be window space with northern exposure.

It is believed that daylight causes less eyestrain and fatigue than any

other light. Also, shadows from the head, hands, and instruments

are reduced to a minimum if north light is used. Examination of

seeds by natural daylight often avoids confusion over color, texture,

and brilliance. With proper provisions for daylight, artificial light is

required only on the darkest days or during early mornings and late

afternoons of the short winter days. If artificial light is used the

analysts should have individual, adjustable, multiple-tube, fluorescent

lamps of the daylight type.

DESKS AND TABLES

Work tables or desks should be large enough to accommodate the

worker's arms, his workboard, working tools, and instruments as well

as to provide space for writing. Itis highly desirable to have movable

desks or tables, especially if light from a northern exposure is not

available. In this way the analyst can shift his table to obtain the

greatest benefit from the available natural light and at the same time

avoid direct sunlight and shadows.

THE USE OF EQUIPMENT

WORKBOARDS

In testing large seeds a workboard equipped with a drawer or a

pan which will hold all the pure seed is desirable. The height, width,

and covering for the board should suit the individual analyst. The

following working surfaces are commonly used: (1) Frosted glass

42
TESTING AGRICULTURAL AND VEGETABLE SEEDS 43

slab; (2) plate glass covered with a lightweight, nonglare blue or

white paper, applied wet and fastened firmly to the under side of the

glass with gummed paper; and (3) a wooden surface covered with a

nonglare white or light blue bond paper which is resistant to wear and

tear from constant motion of the forceps and does not buckle.

If the workboard is made of soft wood, the paper may be fastened

in place with thumbtacks. The usual method of applying the paper

is to cover the arm rests first. Two sheets of paper are used for the

top cover, each a little narrower and a little longer than the top of the

board. One sheet is fastened flush with the front of the board by

inserting thumbtacks in the two front corners. The other sheet is

placed over the first sheet so that it extends from the back of the board

to within approximately 2 inches of the front edge. The second sheet

is attached by thumbtacks at each end of the four corners. A scoop or

pouring device can be made from an ordinary card by folding approximately 1 inch, along one side, until it makes a 90° angle with the

remainder of the card. The wide part of the card is slipped between

the two cover sheets and the upright edge serves as a retainer to keep

the seeds from being pulled off the board. The card is easily removed

and serves as a convenient pouring device. The scoop cannot be conveniently used with the glass slab and plate glass workboard covers

mentioned above.

SEED CONTAINERS

Containers for seeds must be large enough to accommodate the sample, yet not so large as to be awkward to handle. Any container which

is light and does not take on a static charge is satisfactory. Glass

has some advantages over other materials, the principal advantage

being that, when slipped under a microscope to examine seeds, light

is not reflected into the eyes of the observer ; bright metal containers

should not be used because they are such good reflectors. Small Petri

dishes, 50 mm. in diameter and 10 mm. deep are adequate for samples

up to 10 grams. When testing large samples one larger container is

needed for the pure seed component butthe small dishes can be used for

the other three components. There is an obvious space-saving advantage in containers which nest. An assortment of seed pans with

pouring spouts is almost indispensable. Glass vials with corks,

gelatin capsules, and two or three sizes of coin envelopes are essential

for filing the components after the final weighing. Bell jars or plastic

cake covers should always be on hand to cover the working sample

if the analyst leaves his work, even for a moment.

SEED DIVIDERS

The sample submitted for test must be reduced to the size recommended for the kind of seed under consideration. Mechanical dividers

are generally used to accomplish this. Different kinds of dividers are

described under "Seed Sampling and Testing Equipment" and methods of reducing the sample are discussed under "Obtaining the Seed

Sample." In most dividers there is a possibility that seed will lodge.

Unless the divider is thoroughly cleaned these lodged seeds will be left

to contaminate other samples. As insurance against such possible

contamination the habit of thoroughly cleaning the divider before and

after each use should be definitely established. The divider may be

957116—52 4
44 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

cleaned by a strong air current from air under pressure, a portable

dust blower, or other means.

Most dividers are constructed so as to cut the sample into two parts

with each division. The seeds in one pan should be set aside after

each division and the other half run through the divider again until

the sample is approximately the size required for test. It is convenient

at this point to have a torsion balance or a scale, accurate to a tenth

of a gram, to determine the approximate weight of the reduced sample. If it is found that the weight of the sample is less than that

required for purity analysis it can be increased by dividing the setaside-portion of seed from the other pan a sufficient number of times

to provide the difference. If the sample is too large it can be reduced

by repeated mechanical division. The sample must not be altered

by adding or removing seeds by hand.

SCALES AND BALANCES

Scales and balances should be located on heavy, level, stationary

tables or shelves where they will be free from jolting and vibration.

Scales and torsion balances should be checked for balance and accuracy

at regular intervals, and analytical balances should be checked before

each use. Extreme care in operating analytical balances is essential

to their continued accurate service. The pans should always be gently

lowered to the weighing position and released with an easy gentle

motion. Quick, abrupt movements do not make the balance work

faster but get it out of adjustment quickly. The analyst must have a

complete understanding of the metric system of weights and know

the decimal fraction which each position on the beam and vernier

represents. Errors in reports have been traced to misplacement of

the decimal point and omission of a zero in the fraction.

The worm gear which operates the vernier and tape or chain sometimes requires cleaning and oiling. This can be done by cleaning the

gear with carbon tetrachloride, removing accumulated dust with a

soft lintless cloth and oiling with a drop or two of good-quality

machine oil.

The rules for seed testing ^ provide that the working sample shall

be weighed to four significant places and each component of the separation shall be weighed to the same number of decimal places. This

causes a slight conflict because working samples, weighing 1, 10, and

100 grams, or slightly more, usually yield components whose weights

are 1 digit less than the weight of the original samples. Thus, in samples of 1.015 grams, 10.15 grams, and 101.5 grams, the heaviest component (pure seed) might be 0.987, 9.87, and 98.7 grams, respectively.

Hence, if the rules are followed strictly in these cases, the original

sample is weighed to four significant places but the components to no

more than three places.

The number of significant figures is determined by the weight of

the greatest component, zeros of the same order in the lesser weights

being considered significant. Digits are significant whether they are

before or after the decimal point.

^ The expressions "the rules" and the ''rules for seed testing" refer to the

Rules for Seed Testing (see Appendix) as followed in the administration Of

the Federal Seed Act and the Rules of the Association of Official Seed Analysts.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 45

Table 2 shows the number of decimal places to which samples of

different groups must be weighed in order to insure four significant

figures for the components.

TABLE 2.—Guide to the numher of decimalplaces for weighing working

sainples and oomponents to insure fow signißcmit figv/res

Working sample Components ^ of separation

Weight specified in rules Example

Number of

decimal

places

Example

Grayns

0.5

LO

2.0

5.0

10. 0

25.0

50.0

100. 0

500.0

Grams

0. 5108

1. 012

2. 025

5. 108

10. 02

25. 59

51. 63

102.8

504. 2

4

3

2

1

Grams

P 0. 9876

C . 0014

I . 0102

W . 0031

1. 0023

P 9. 876

C . 014

I . 102

W . 031

10. 023

P 98. 76

C . 14

I 1. 02

W .31

100.23

P 487. 6

C 1.4

I 10.2

W 3. 1

502.3

1 The components of the separation are indicated as follows: P=pure seed;

C = other crop seed; I =inert matter; W = weed seed.

HAND LENS

A triplet (triple aplanat) hand lens which magnifies five, six, or

seven diameters is an efficient and convenient size for ordinary use.

One which magnifies ten, twelve, or fourteen diameters is often used

for separations of smaller amounts of seeds such as 400-seed separations of redtop and creeping bentgrass. To prevent eyestrain, hold

the lens in the left hand, supported by placing the base of the thumb

or hand against the forehead in such a manner that the lens will

be directly in front of one eye. The analyst should learn to keep

both eyes open while using the lens and to use either eye. Lack of

exercise may result in weakened muscles of the idle eye. With the

lens in the left hand and forceps in the right hand lower the head
46 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

and arms until the forearms rest on the armrests of the workboard

and the seed is in focus when viewed through the hand lens. The

seed will be in focus when the lens is approximately 1% to 2 inches

away. Proceed with the separation as indicated under the heading

"The Purity Separation."

SEED BLOWER

The analyses of many samples, especially grasses, can be facilitated

by removing the lightweight material with the aid of a seed blower.

The sample to be analyzed should be examined and if it contains lightweight material the appropriate blower or blower combination should

be used. Generally, several blowings are made at successively wider

gate or valve openings. The fraction from each blowing is examined

atthe workboard by the aid of a hand lens or magnifying glass and the

different components present are separated and placed in dishes or

vials. The blowing and examination are continued until all the

lightweight material is removed from the heavy fraction.

A record book, in which are recorded the gate or valve openings

used for the different kinds of seeds, should be kept near the blower.

The point at which pure seed begins to blow over and the point at

which all lightweight material has been removed should be indicated.

This serves as a guide for blowing subsequent samples of the same

kind of seed.

THE PURITY SEPARATION

PRELIMINARY SEPARATION

The sample is reduced in size (preferably with a mechanical divider) and the weight of the working sample determined in accordance with the foregoing procedures. The separation is then made

as follows : Place the seed on the clean surface of a workboard and

examine to determine whether the sample : (1) Conforms to the name

under which it was submitted; (2) contains small inert matter which

should be removed by sieving; and (3) contains lightweight material

which may be removed by blowing.

If inert matter is present which can be removed by sieving or a preliminary blowing, use the appropriate sieve or blow the sample in

accordance with the procedure previously described. After these

operations pour the sample in a pile on the workboard, slightly to

the rear and left of center. With the aid of forceps, scalpel, or spatula

having straight smooth edges draw a few seeds at a time from the

pile, spreading them apart by pulling them toward the front of the

board. As small groups of seed are being examined pull the pure seed

into the scoop or container at the front of the workboard and push

all other material to the upper right of the board for further examination. Continue this operation until the entire sample is separated.

Many samples of grass seed will require several blowings beyond

the first one which removes only the empty florets. The next blowing

should remove some empty and some filled florets. The sample should

be blown until the heavy portion or residue contains no inert florets

of the seed under consideration. The portion removed at each successive blowing should be separated into pure seed, crop seed, weed

seed, and inert matter.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 47

CHECKING FOR ACCURACY

After this examination return the pure seed to the workboard for

further examination as indicated below : If the kind of seed requires

a working sample of 50 grams or more, it is usually not necessary to

use magnification in checking, although it is frequently desirable to

examine the foreign seeds and inert matter under magnification. In

samples of less than 50 grams all components, including pure seed,

should be checked under magnification. After all the pure seed is

checked, examine and separate the foreign material into other crop

seeds, weed seeds, and inert matter.

WEIGHING, RECORDING, AND CALCULATING PERCENTAGES

Each of the four components must be weighed. There should be

not more than 1 percent variation between the weight of the original

sample and the total weight of the four components. If the gain or

loss is greater than this amount another test should be made.

All pertinent data should be recorded in ink on a permanent record

card. The data to be kept include weight and percentage of each

component, the character of inert material, kinds and numbers of

other crop and weed seeds, name or initial of analyst, and date of test.

AH reports should be made from this record. The percentages of the

components are determined by dividing the weight of each by the

sum of the weights of the four components, and not by the original

weight of the sample. The record should be filed in a readily accessible place.

SEPARATING SEEDS OF SIMILAR KINDS AND VARIETIES

The rules for testing provide for the use of as few as 400 seeds in

those cases where the working sample consists of two similar species

or a species and its variety, which would require an excessive amount

of time, eyestrain, and effort for separation of the entire working

sample. Since tolerance tables for 400, 800, and 1,000 seeds are included in the rules of the Association of Official Seed Analysts it is

recommended that one of these amounts be used. Frequently, when

the separation is so difficult that a reduced sample is used it will be

found that a stereoscopic microscope will often be helpful or even

essential. In testing mixtures of creeping and colonial bentgrass

seed most of the separation can be made with a hand lens by an experienced analyst but the microscope is essential for identifying those

few nontypical seeds which seem to be present in every sample. It is

also essential to use the microscope in making positive identifications

of some weed seeds.

INTERPRETATION OF CROP SEED

APPLICABLE RULE

The following rule applies to both the pure seed and other crop

seed when determining whether shriveled, cracked, broken, insectinjured, and diseased "seeds" should be considered inert matter or

seed : Any pure seed or crop seed that comprises one-half, or less than

one-half, its original size (not weight) is considered inert matter;

otherwise, it is to be regarded as a seed.
48 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

BROKEN AND CRACKED SEEDS

Legume seeds usually break along the line of cleavage between the

cotyledons. To be considered as pure seed a seed fragment must have

its half of the seed coat as well as the radicle attached. Rye and barley seeds frequently break transversely. When in question line up the

broken fragments on a workboard and place several normal, unbroken seeds of various sizes alongside them. From this comparison

estimate the original size of each fragment and decide whether it represents one-half or more of the original seed.

The fragment does not have to contain an embryo in order to be

regarded as pure seed. A similar procedure can be followed in determining the relative proportion of the original size which seed

fragments in different groups represent. All cracked seeds are regarded as pure seed if the seed or fragment consists of more than

one-half the original structure.

IMMATURE AND SHRIVELED SEEDS

Occasionally samples contain relatively high percentages of immature seeds which the analyst may think should be sifted and included

with the inert material. Immature seeds are particularly prevalent

in uncleaned seed lots. All these seeds are to be regarded as pure

seed if they can be definitely identified as being the kind under consideration.

IMMATURE SEEDS IN GRASSES

This group differs from the preceding one in that the caryopses or

seeds are enclosed within the lemma and palea. To apply the half seed

rule in determining purity in grasses the question arises as to just how

well developed the ovary must be to fulfill the definition of a seed.

The difficulty in making this determination in grasses has led to

varying results when tests have been made by different analysts. Before attempting to separate inert matter from pure seed in grasses

the analyst should thoroughly acquaint himself with all the structures

of the normal pure-seed unit. The caryopsis should be removed and

studied as a basis of comparison between it and the immature, diseased,

or empty florets. Although most of the grass seeds received for testingare florets consisting of a caryopsis enclosed by the lemma and palea

the seed unit in some kinds is composed of the entire spikelet.

The- separation of pure seed and inert matter is rather simple in

those grasses with thin papery glumes as it is possible to see through

the lemma and palea and determine the presence or absence of a

caryopsis. Grasses with thick, horny lemmas and paleas are more

difficult to classify as one cannot see through them and must resort

either to reflected light or to some form of pressure. Standard blowing procedures and schedules have been adopted for Canada bluegrass

and Kentucky bluegrass seed. These procedures are set forth on

pages 67 to 70.

EMPTY FRUITS IN THE COMPOSITE FAMILY

Although it appears logical that the one-half seed rule should

prevail in testing seeds of chicory, endive, lettuce, and sunflower this

procedure is not practical of application. The so-called seed is a fruit

(achene) of which the outer structures are comparable to the pod in the

legumes. The true seed may or may not form inside the fruit and
TESTING AGRICULTURAL AND VEGETABLE SEEDS 49

it is not feasible to make this determination for all seeds. For example,

in chicory some fruits are thin-walled but have heavy seeds within

whereas others have very thick walls with immature seeds or no seeds.

The filled and empty fruits do not separate in blowing and it would

be impractical to open each fruit to determine its content. Opening

the fruits would render the sample inadequate for germination purposes. All of these whole fruits are considered to be pure seed or crop

seed as the case may be. Only broken fruits found to contain no true

seeds or one-half seed or less are to be regarded as inert matter.

SEEDS OF LEGUMES AND CRUCIFERS WITH THE SEED COAT REMOVED

Crop seeds in the legume and crucifer (mustard) families with the

seed coat entirely removed are classed as inert. To properly classify

seeds without the seed coats it is necessary that they be identified as

belonging to one of these two families. As a means of identification

some normal, well-filled seeds of known samples should have the seed

coats removed for comparison with the seeds in question.

INSECT-DAMAGED SEED

Insect-damaged seeds of pure seed and crop seed are also classified

by the so-called one-half seed rule. If one-half or more than one-half

of the seed has been consumed by the insect itis considered inert matter.

With experience, most analysts will be able to determine insect-infested

seeds by visual examination alone. For further information on this

subject the reader is referred to particular groups listed under the

heading "Application of Purity Procedures to Specific Groups of

Seeds."

SCLEROTIA AND NEMATODE GALLS

In some instances nematodes have replaced most or all of the contents

of the seed, forming nematode galls. In other instances mycelia of

fungi have developed to the extent that they replace the contents of

the seed, forming sclerotia. Although these nematode galls and sclerotia alter the inner contents of the seed there is a marked resemblance

to true seeds, from outer appearances. These structures should be

considered inert matter. Nematode infestations are frequently found

in fescue and bentgrass seed and occasionally in wheat. Ryegrass seed

infected with the blindseed fungus {Phialea tenmlenta) is not a

sclerotium and thus should be classified as pure seed. Frequently,

ergot replaces only a portion of the seed, especially in redtop. In

such instances each seed must be considered on its own merits in applying the one-half seed rule. A diaphanoscope is often helpful in detecting the presence of ergot and other sclerotia. If nematodes are

suspected a positive test can be made by crushing the seedlike structure^ placing it in water for a few hours and then examining it under

a niicroscope. The nematodes (eelworms) become active and can be

easiLy identified by their wormlike motion.

INTERPRETATION OF WEED SEED

APPLICABLE RULE

The rules for seed testing set forth the nature of seedlike structures

of weeds which are not to be regarded as weed seeds, and they inditate

nine specific kinds and types of structures to be included with inert
50 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

matter. The following example is an attempt to clarify procedure

with respect to these characteristics and seed types, which may be

found in the rules (see pp. 337-338). If the analyst encounters a

structure not specifically covered in the rules he should regard it as

a weed seed unless he can definitely demonstrate by visual examination

that it either has no embryo, has a rudimentary embryo, or has an

embryo that has been destroyed by a disease organism.

METHODS OF EXAMINATION

Dissection of the seed and examination by reñected light are acceptable methods of examination. By dissection the seed is divided

into separate parts for examination. From this definition it is seen

that crushing cannot be substituted for dissection. Crushing destroys

the seed material and makes it useless for careful examination. In

grasses, with thin glumes, and in composites, with thin fruit coats,

examination over a diaphanoscope may assist in differentiating between weed seeds and inert matter.

RUDIMENTARY EMBRYO

A rudimentary embryo is one which is imperfectly developed and

functionally useless. It is usually difficult or impossible to determine

that a seed has only a rudimentary embryo, or the stage of development at which it ceases being a rudiment and actually becomes an

embryo. The analyst must be able to correctly identify the seed and

have an understanding of its morphology, especially the size and

location of the embryo. If this is not known dissect good seeds to

get this information. In seeds of Gyperus the embryo is very small

and lies at the base of the seed (achene) just above the point of attachment, unless the analyst knows the location of the embryo he

could very easily fail to find it and possibly classify the seed as inert.

The situation is different in the composites in which ^11 the seed (except seed coat) is embryo. Therefore, if upon dissection there is any

structure within, it must be interpreted as a seed. Before classifying

any seed believed to contain a rudimentary embryo as inert the analyst

must satisfy himself that it is positively incapable of producing a

plant.

GRASS SEEDS WITH EMBRYOS BROKEN OR ABSENT

Quackgrass {Agropyron repens) seed is frequently broken, especially when occurring in sweetclover seed. If more than one-half the

embryo in a grass seed is missing the seed is regarded as inert. Normal

seeds of the kind in question should be critically examined to determine the length, width, and thickness of the embryo in relation to the

whole seed.

DODDER SEEDS

Seeds of dodder which are fragile, ashen gray to brown in color,

and somewhat enlarged are included with inert matter. Before checking for the presence or absence of an embryo the analyst must know

the internal structure of the seed and recall that the embryo, surrounded by the endosperm, lies coiled in the center of the seed. The

analyst will become more certain of his interpretations if he first

judges the seed from outward appearances and then carefully dissects

it, noting whether the embryo area is empty or filled. Many samples

have some dodder seeds which are definitely inert, others which are
TESTING AGRICULTURAL AND VEGETABLE SEEDS 51

definitely weed seeds, and others which are of questionable classification.

To avoid the dissection of a large number of seeds the questionable

group is lined up in the order of quality as determined by outward

appearances. In this group the one least likely to contain an embryo

is dissected ; if it has no embryo, the next likely ones are dissected until

one or two seeds with embryos have been found. All seeds appearing

better than the latter are regarded as good seeds.

NAKED RAGWEED SEED

There is no difficulty in determining the presence or absence of the

pericarp and involucre in ragweed seed. It is important that these

naked seeds (embryos) be correctly identified as coming from ragweed

and not from some other composite plant.

SHRIVELED SEEDS OF BUCKHORN

The rule requiring that shriveled blackened seeds of buckhorn shall

be classified as inert matter has caused much trouble. Questions frequently asked are : "How shriveled and how blackened?" All degrees

of shriveling and blackening exist in some samples. Any seeds which

can definitely be identified as buckhorn {Plantago lanceolata) ^ when

compared with known samples, should be classed as weeds. If the

seed is shriveled and discolored to the extent that it can be identified

to genus only, it should be considered as inert matter. The identification should be based on the merits of each seed and not on the fact

thatthe sample contains well-developed seeds of buckhorn and no other

species of Plantago,

GRASS FLORETS WITH IMMATURE CARYOPSES

Seeds of grasses which have developed only slightly beyond the

flower stage are to be classed as inert or weeds depending on the development of the ovary. This is not too difficult in larger seeds such as

Johnson grass but it can be extremely difficult in small seeds such as

the weedy species of Agrostis^ Eragrostis^ Panicum, Poa^ and Polypogon. The only dependable criterion in either case is removal of the

caryopsis from the palea and lemma and comparison with normal seeds

of the same species. For small seeds it is necessary to use the stereoscopic microscope in making some of the determinations. Caution

must be exercised not to confuse dried-up stamens with immature

caryopses.

EMPTY FRUITS OR ACHENES

Empty seeds or fruits of weedy plants such as occur in the buckwheat

and composite families can often be detected either with reflected light

or by dissection. As in the dodders it may be necessary to dissect or

examine only a few seeds in the questionable group.

WEED SEEDS WITH THE SEED COATS REMOVED

The only weed seeds with seed coats removed to be regarded as

inert matter are those of the legume family and the genus Brassica of

the mustard family. This differs from the classification of crop seeds

in that crop seeds without seed coats in the entire mustard family are

classified as inert matter, whereas the only weed seeds without seed

coats in this family to be classified as inert matter are sj)ecies of
52 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Brassica, Thus, a weed seed without seed coat which can be identified

as belonging to the legume family or the genus Brassica is to be

regarded as inert mattei.

WILD ONION AND WILD GARLIC BULBLETS

The basal or stem-end portion of bulblets of wild onion and wild

garlic must be present if the bulblet is to be considered a weed. Eegardless of size the bulblets must be considered as weed seeds if they

possess characteristics by which they can be identified, provided that

the stem-end portion is present.

SPECIAL TESTS AND PROCEDURES

VARIETAL IDENTIFICATION

Varietal separation by seed character can sometimes be made with

accuracy but usually this is not possible. Frequently all the plants of

certain varieties in field trials cannot be positively identified. It is

the responsibility of each analyst to familiarize himself with the possibilities of variety identification of the kinds with which he works and

to let that knowledge govern the extent to which such separations are

attempted. Space does not permit a discussion of the varietal character

in different groups. Usually, the identification of varieties must be

accomplished through greenhouse and field plantings.

PLANTING INCIDENTAL SEEDS FOR IDENTIFICATION

Incidental seeds which cannot be identified in the laboratory with

certainty should, Avherever possible, be tested by planting in a greenhouse or field and the plants produced from these seeds should be identified by a specialist for the group. To make sure that no other seeds

are present in the soil used for the test only sterilized soil should be

used. Seeds planted in the greenhouse often do not respond as they

do in their usual habitat and at times produce plants which are so

different from the normal that specialists find it difficult to identify

them. It is necessary that a person attempting to grow plants understand their requirements and try to provide these conditions for each

kind of plant. Adverse w^eather and climatic conditions and danger

of contamination with other kinds make field plantings for identification of incidental seeds hazardous.

TESTING OF COATED AND PELLETED SEED

In recent years seeds encased with an inert covering have appeared

in trade channels under such designations as "coated" and "pelleted"

seed. Two processes have been used in covering thé seed. In one

process individual seeds are covered, and in the other process the

number of seeds covered may range from one to several. Occasionally,

an inert fragment is covered. In that case the pellet would be devoid

of a seed.

No special provisions have been incorporated into the present rules

for the testing of such seed for purity and germination. If the "coating" or "pelleting" of seed becomes a regular practice, standard methods of testing will have to be devised whereby analysts may determine

whether such seed is sold in compliance with existing laws. Laboratories conducting service tests will also be testing seed lots subsequent
TESTING AGRICULTURAL AND VEGETABLE SLEDS 53

to pelleting, particularly carry-over stocks, for seedsmen and merchants. The exact laboratory procedures adopted will depend to a

great extent on whether the "pellets," including the seed and coating

material, or the true seed within the coating material is to be considered

the unit for testing. The present rules for testing seed would have to

be interpreted to mean that the true seed is the unit for test. The

principal problem in the purity analysis appears to be that of removing

the "covering" in order to determine the component parts of the sample

and whether weed seeds, including noxious-weed seeds, are present.

For purity analyses made in accordance with the present rules the

sample sizes would have to be those set forth in the rules, after the

inert coating is removed. The coating can be removed by soaking it

loose and straining off the inert material after which the seed is thoroughly dried. The weights of the pure seed, crop seed, and weedseed components are determined as in a regular test. The difference

between the total of these weights and the original sample weight

represents the weight of the inert component.

OTHER SPECIAL TESTS

Certain other special tests such as varietal analysis of Sudan grass,

mottled-seed test of sweetclover, and fluorescence test of ryegrass will

be found under the specific groups and kinds to which the tests apply

under the heading "Application of Purity Procedures to Specific

Groups, of Seeds."
APPLICATION OF PURITY PROCEDURES TO SPECIFIC

GROUPS OF SEEDS

The first step in making a purity analysis is to examine the sample

of seed submitted for test to determine whether it is correctly named.

The i)urity analysis and noxious-weed seed examination of all the

small grass and legume seeds must be made with the aid of a hand

lens. A reading glass may be substituted for the hand lens in examining some samples of large seeds such as Sudan grass and Crotalaria.

A stereoscopic microscope is necessary for examination of seeds of

questionable identity or classification.

The principal aids in seed identification include seed keys, descriptions, illustrations, and comparison with seeds of known identity. In

cases of doubt the identified seed should be compared with samples

of the same species, or related species, showing a range of variation.

When there is doubt with respect to the identification of naked caryopses of grasses, and naked seeds from achenes and other fruits, seeds

of known identity of the kind suspected should be removed from the

husks for comparison. The known range of plants as determined

from botanical manuals is frequently an important aid in seed identification.

The grain or seed in the grass family (Gramineae) is frequently

enclosed by the lemma and palea, referred to variously as glumes,

chaff, and husks. Commercial seeds of the grasses (most cereals and

some other grasses excepted) are usually enclosed within these structures and the entire unit is referred to as a seed. In sonie cases the

seed unit is a one-seeded spikelet; whereas, in some species the seed

unit is a spikelet with several seeds. The analyst must be familiar

with the structures constituting the seed unit in each group in order

to make accurate identifications and distinctions between pure seed

and inert matter. A typical grass spikelet is illustrated in figure 63,

page 195. Most elementary grass manuals contain descriptions and

illustrations of the flowers, fruits, and spikelets in the grasses.

In seeds of the grass family the inert matter consists chiefly of the

following : Florets, of both weed and crop species, which are empty

or contain only anthers or undeveloped ovaries ; pieces of pure seeds

and other crop seeds which have been reduced to one-half or less their

original size by mechanical injury, insect infestation, or destruction

by rodents ; pieces of sticks and stems, chaff, and dirt; occasional

empty fruits or seeds of weeds ; seeds of Jwncu^ spp. if not more than

one-tenth percent; smut (round, dark brown balls often contained in

lemmas and paleas) ; ergot (dull purplish black, thicker and longer

than caryopses) ; and nematode galls (shiny black to glossy amber and

spindle-shaped). When dropped into water and allowed to stand for

about half an hour nematodes will appear as a small cottony tuft.

If a portion of a nematode gall is crushed and placed in water on a

54
TESTING AGRICULTURAL AND VEGETABLE SEEDS 55

microscope slide and examined under a microscope, the eelworms can

be observed within a few moments.

Inert matter in legume and other seeds consists chiefly of : Pieces

of pure seed and other crop seed which have been reduced to one-half

or less of their original size by mechanical injury, insect infestation,

or destruction by rodents; pieces of sticks and stems, chaif, and dirt;

and occasionally empty fruits or seeds of weeds.

GRAMINEAE (GRASS FAMILY)

AGROPYRON AND ELYMUS—WHEATGRASSES AND WILD-RYE

Key to lUus-

^^. , , . species, tration,

Kmdofseed page Plate

Agropyron cristatum—Fairway crested wheatgrass 200 I, 13

^1. desertorum (A. cristatum)—Standard crested wheatgrass 200 I, 14

A. trachycaulum (A. pauciflorum)—Slender wheatgrass 200 I, 11

A. smithii—Western wheatgrass 201 I, 10

Elymus canadensis—Canada wild-rye 215 IV, 81

Seed unit.—Free caryopsis or floret with a caryopsis.

Special treatTTient,—Samples should be partially separated with a

seed blower. If extraneous material is present after blowing, some of

the hand separation may be eliminated by sifting. Separate the

multiple florets if one or more contains a pure seed. Include the

empty florets with the inert matter.

Special problems.—^A bulk sample of Fairway crested wheatgrass

seed can be distinguished from seed of Standard crested wheatgrass

but it is not possible to distinguish all of the individual seeds.

It is easy to overlook seeds of Agropyron repens and other species

of Agropyron and Elymus spjp. in samples of A. trachycamlum^ A.

smithii^ and Elymus canadensis. Examine all seeds critically with a

hand lens, removing any which appear not to have all the characters of

the pure seeds. Under magnification place all questionable seeds next

to known normal seeds for final determination.

AGROSTIS—REDTOP AND BENTGRASSES

Key to IllusT^. . , , species, tration, Kmdofseed page PMe

Agrostis alba—Redtop 197 j j

A. camna—Velvet bent '__~_" 198 l'5

A. palustris—Creeping bent 198

A, tennis—Colonial bent 198 12

A. tennis var.—Astoria bent ]__^__ 198

A. tennis YSiV.—Highland bent 197 I'"""'

Seed unit.—Caryopsis; floret or spikelet with caryopsis.

Special treatment.—Pr2iCticsillj all samples of Agrostis require

blowing. If samples contain fine dirt and small weed seeds it is

advantageous to sift the heavy seed left after blowing. Sieves with

round holes 0.508 and 0.612 mm. in diameter are most effective. These

sieves will remove fine dirt as well as some tiny weed seeds.

While the purity test is being made the analyst should take special

note of the Agrostis and determine whether there is more than one

species present. If more than one species is present, a detailed separa-
56 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

tioii of the different species must be made. At least 400 seeds must

be taken indiscriminately from the pure seed fraction, after the regular

purity analysis has been made, for this detailed separation.

Special proMems.—Separating the species and varieties in the 400

or more seed test of Agrostis should not be undertaken except by

trained and experienced analysts. Although most of the seeds can

be separated into kinds, there are often a few seeds which cannot

definitely be identified. Naked caryopses are included in the separation but no attempt is made to identify them.

The procedure and calculations are indicated in the following example (developed by the Standardized Test Committee) for a

400-seed separation of Agrostis with 95.07 percent pure Agrostis^ no

other crop seed, 4.32 percent inert matter, and 0.61 percent weed seed :

Where no field information is available—

Weight, Percentage

Grams in sample

Total Agrostis, including naked caryopses 0. 9524 95. 07

400 seeds with lemma and palea plus naked caryopses are examined.

No. seeds Percent

Naked caryopses 117 22.63^

(Report as unidentified)

Creeping bent 173 33. 46

Redtop 147 28. 43

Brown top 80 15. 48^

Total 517 100.00

>X95. 07

21. 52^

31.81

27. 03

14. 7i;

H9Ö. 07

Samples of Agrostis submitted for test often have the glumes, as

well as the lemmas and paleas, present. These seeds are generally

termed as "unhuUed." In the lighter blowings it is often necessary

to remove the seed from these glumes before it is possible to determine

whether or not there is a seed present. In the heavy portion it is

sometimes possible to allow all those seeds with glumes to remain with

the pure seed but e.nough should be removed from the glumes and

examined critically to determine with certainty that these hulls contain seed and not ergot or other foreign substances.

Samples of Agrostis often contain naked caryopses of bluegrass

which are not difficult to distinguish. The caryopses of Agrostis are

amber brown in color, transparent, rounded at both ends with^ a

rounded, well-defined embryo area on one side and a crease or definite

fold along the other side. The seed lies flat on this fold. In cross

section it somewhat resembles the capital letter "B."

Bluegrass caryopses are of similar sizes but orange brown in color,

opaque, pointed at the ends with the embryo area obscure and poorly

defined. The caryopsis of Poa has a keel on the embryo side and a

flat face on the hilum or opposite side. In cross section bluegrass seed

is triangular.

Tiny seeds of several weeds including some weedy species of

Agrostis which might easily be overlooked in samples of Agrostis are :

ParentuceUia, Junem, Downingia, LoheUa^ Epilohium. In Redtop

there are often light-colored, inflated, shiny seeds of AcMllea millefolium which, when dissected, appear to contain insect larvae. These

must be included with the inert matter.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 57

ANDROPOGON, BOUTELOUA, SORGHASTRUM—BLUESTEMS, GRAMAS, AND INDIAN

GRASS

Key to Illusspecies, tration,

Kind ofseed Page Plate

Andropogon gerardi (A. furcatus)—Big bluestem. 203 II, 25

A. hallii—-Sand bluestem 203 II, 26

A, scoparius—Little bluestem 203 II, 27

Bouteloua curtipendula—Side-oats grama 209 II, 46

B. gracilis—Blue grama 209 II, 47

Sorghastrum nutans—Yellow Indian grass

Seed unit,—Naked caryopsis; spikelet or floret with at least one

caryopsis.

/Special treatment,—Because of the presence of awns, hairs, and

rachillae, the seeds stick together badly so that satisfactory sampling

and blowing are difficult. If the sample mats to the extent that it

cannot be accurately sampled with a mechanical divider, use the

halving method. If the sample lodges in the blower tube, blow smaller

portions at a time, combining the separations of the blowings ; or use

a 3- to 4-inch blowing tube. Multiple florets are not separated in

these tests.

Special problems.—If it becomes necessary to determine whether

the seed units contain caryopses examine the blowings critically as

the glumes of these grasses are horny and not transparent. Dissection

may be required but, in this event, care must be exercised not to injure

any caryopses which may be present.. The sample should be blown

until all of the heaviest spikelets and florets contain pure seed. There

are some confusing weedy species in the group which must be critically

compared with verified specimens to determine their identity.

Lots of these species are sometimes processed in such a manner that

most of the glumes are removed. In processing, the seed loses some

of its characters commonly used for identification, making separation

of species of crop and weed seeds difficult or impossible. Some seeds

are broken during processing, making it necessary to judge them on

the half-seed basis.

AVENA—OATS

Key to Illusspecies, tration,

Kind ofseed Page Plate

Avena sativa—White oats 207 II, 36

A.hyzantina—Red oats 207 II, 37

Seed unit.—Free caryopsis, floret or spikelet.

Special treatment.—If the sample contains empty florets or insectinfested florets it should be blown in a 3- to é-inch blower tube; or

the sample should be divided and a small portion blown at a time.

White oats should be sifted in a slotted sieve 0.064 x % inch which

will remove chaff and single florets of Agropyron repens.^ if present.

This sieve will not remove many of the multiple florets of A. repens.

If after sieving one finds single florets of A. repens in the pan it is

an indication of the possibility of multiple florets being present in

the top sieve.

Special problems.—BecsiMse of lack of development or incomplete

development, the lemma of the primary floret frequently encloses the

secondary floret completely or in part. These should be separated
58 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

in those cases where the tip of the secondary floret protrudes or

diverges from the primary floret. In those instances where the lemma

of the primary floret encloses the secondary floret to the extent that

the tips of the florets do not diverge, separation of the two florets is

not practical, nor does it increase the accuracy appreciably.

Wild oat, Avena fatua^ a weed, is often found in cultivated oats.

Fatuoid forms of certain varieties of cultivated oats appear in samples

of varieties from which they are derived. They usually have one

or more of the characters of A. fatua such as the sucker mouth, hairy

base, rachilla with a cup at the tip, rough lemma, and heavy twisted

awn.

Among the fatuoid seeds there are some which are homozygous and

produce only fatuoid plants but there are others which are heterozygous and produce both fatuoid plants and normal plants. The two

forms are usually indistinguishable and must be put in the same

classification. Fatuoid oats have been classified as pure seed, other

crop seed, and weed seed by different laboratories. Since no method

of eliminating fatuoid forms from pure varieties and strains of oats

has been found they are placed with the pure seed for purposes of

administering the Federal Seed Act. It is frequently desirable to

determine the percentage of fatuoid oats separately and add this to

the percentage of the component indicated by the particular State

laws and regulations or by the seedsman.

There are sometimes seeds in cultivated oats which faintly resemble

fatuoids which cannot be accurately distinguished from pure cultivated oats. Since these,may produce pure cultivated oats, they are

included with the pm^e seed.

Itis possible to distinguish the seeds of certain varieties and groups

of varieties of oats, particularly certain varieties of Averm hy^antina.

Testing oats for variety is generally done on a sample of 20 to 30

grams in weight which gives at least 400 seeds. This portion is taken

indiscriminately from the pure seed fraction after a regular purity

analysis has been made. The naked caryopses should not be used in

making this separation unless a variety is present which is known to

shatter from the lemma and palea to a greater extent than other

varieties present.

The following example illustrates the procedure and method of

calculating the results :

Example—

Total percentage of oats in regular purity analysis 98.79 percent.

Weight of sample for variety determination 25.35 grams.

Percent of

Wt. in gm. Percent sample

Victorgrain 23.91 94.43X98.79 == 93.29

Fulgrain .99 3.91X98.79 = 3.86

Other oats .42 1.66X98.79 = 1.64

AXONOPUS AND PASPALUM—CARPET GRASS, DALLIS GRASS, AND OTHERS

Key to Illusspecies, tration,

Kind ofseed P^Qe Plate

Axonopus affinis—Carpet grass 208 II, 42

Paspalum dilatatum—Dallis grass 222 VII, 140

P. notaium—Bahía grass 223 VII, 145

P. urvillei—Vasey grass_ 222 VII, 148

B
TESTING AGRICULTURAL AND VEGETABLE SEEDS 59

Seed umt,—Caryopsis, floret with caryopsis, or spikelet with

caryopsis.

Special treatment,—All samples must be blown until all the florets

which are closed (not gaping at the tips) resist the pressure of pointed

forceps. Unless they are blown to this degree it will be necessary to

press each seed in the sample to determine whether it is pure seed

or inert matter.

Special prohlems,—P, urvillei is hairy and tends to lodge in both the

divider and blower. If necessary, obtain the samples by the halvingmethod and blow in a 3- to 4-inch blowing tube ; or separate the sample

into smaller portions and blow each separately.

The thick lemmas and paleas on the seeds of all Paspalmn species

make the purity determination very difficult. Some analysts ñnd

that in addition to blowing and pressing seeds with the forceps that

examination of the individual seeds with the aid of a diaphanoscope

assists in separating the pure seed from the inert matter. Seeds of

all Paspalvmi species are subject to attack by ergot. The normal

caryopses are hard, brittle, and translucent with well-defined embryo ;

those which are ergotized are hard but spongy and opaque with no

clearly defined embryo or embryo area.

Until he becomes entirely familiar with the seeds and the problems

associated with these tests, it is well for the inexperienced analyst to

begin with the heavy portion left in the blower cup. From this portion

remove as inert those florets gaping with ergot; next remove gaping

florets which do not show any ergot. Put these on the workboard,

palea side down ; with a pair of sharp-pointed forceps slightly open,

press on the seed toward the callus end and across the keel. If the

floret contains a pure seed the caryopsis will resist slight pressure, but

if it is inertthe points of the forceps will penetrate the lemma. When

a few florets have been determined in this manner it is advisable to

separate the lemmas and paleas until their contents can be seen and

the interpretations made without complete dissection. It will not be

necessary to open all the florets removed from the heavy portion for

the analyst will soon acquire the ''feel" of both the pure seed and

the inert.

After the heaviest portion has been examined the same procedure

should be followed on each of the blowings, continuing with the next

heaviest blowing successively until one blowing contains only inert

florets. It is ordinarily safe to assume that all blowings lighter than

this are inert matter.

BROMUS—BROME AND RESCUE GRASS

Key to Illus-

-,. , , , species, tration, Kind ofseed Page Plate

Bromus catharticus—Rescue grass 210 III, 56

B. inermis—Smooth brome I 210 IIl|55

B. marginatus—Mountain brome 210 III* 57

Seed unit,—Caryopsis, floret with caryopsis, or spikelet.

Special treatment,—Blow in 3- to 4-inch blower tube or blow smaller

portions and combine the separations of the blowings. Separate the

multiple florets if one or more contains a pure seed.

Special prohlems.—Bulk samples of Bromus catharticm and B,

marginatus can be distinguished but there may be a few individual

957116—52 5
60 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

seeds in the purity analysis which cannot be distinguished with certainty. If one species is found in the other, any indistinguishable

seeds should be included with the pure seed and the following note

affixed to the record : "Certain seeds of B. catharticus and B, marginatus are indistinguishable."

Weedy species of Bromus which might be confused with B, catharticuß and B, marginatus include B, breviaristatus^ B, carinatws^ B,

folyamthus. Bromus inermis often has much light chaff and also

light seed present. Some of the caryopses, both naked and in the

florets, are very thin. If the caryopsis is complete it must be included

with the pure seed regardless of size. Some thin caryopses of B,

inermis are as thin and limber as a sheet of bond paper but still must

be classed as pure seed.

B, inermis often has seeds of several species of Agropyron, Each

seed of Agropyron must be examined critically to separate the crops

from the weeds. In the noxious-weed seed examination remove all

Agropyron spp., then separate Agropyron repens from the other

species by critical examination, including the use of hand lens and

stereoscopic microscope, if necessary.

CYNODON, CYNOSURUS, AND PHALARIS

Key to Illusspecies, trafAon,

Kind ofseed Page Plate

Cynodon dactylon—Bermuda grass III, 62

Cynosurus cristatus—Crested dogtail 213 111,64

Fhalaris arundinacea—Reed canary grass 223 VII, 152

P. canariensis—Canary grass 223 VII, 155

P. tuberosa var. stenoptera—Harding grass 224 VII, 154

Seed wnit,—Caryopsis or floret with caryopsis.

Special treatment,—Phalaris arundinaeea and Cynosurus cristatus

are always blown ; the other kinds are blown and sifted only if light

florets, much fine dirt or many small weed seeds are present.

Special problems,—Determination of pure seed is difficult as the

lemma and palea are so thick and opaque that it is not easy to see

through them. The sample should be blown until all florets with

undeveloped ovaries or only anthers are removed. Until the analyst

becomes thoroughly familiar with the test he should develop the

habit of critically examining those caryopses which he cannot classify

with certainty, from the appearance and "feel" of the florets.

Bermuda grass seed is sometimes processed to remove the lemmas

and paleas. This reduces the pure seed determination to identification

of the species present and to determination of the relative sizes of damaged portions of seeds.

Those seeds of Phalaris with lemmas and paleas can be distinguished

but the identification of the naked caryopses may or may not be possible depending on the species represented.

DACTYLIS—ORCHARD GRASS

Kinâ, of seed

Dactplis glomerata—Orchard grass.

The seed is described on page 213 and iUustrated in plate III, 66.

Seed unit.—Caryopsis or floret with caryopsis.

Special treatment,—Samples often have many multiple florets as

well as other crop and weed seeds of varying sizes, shapes, and weights,
TESTING AGRICULTURAL AND VEGETABLE SEEDS 61

which make it difficult to get a representative sample. The sample

should be thoroughly mixed before the dividing is begun. All multiple

florets must be separated if one or more contains a seed. Separation

of single and multiple florets is facilitated by sifting with slotted

sieves. Sieves with round and triangular holes are aids in removing

Aveed seeds.

Special problems.—It is advisable for the beginner to examine the

heavy portion of seed first in order to become acquainted with the

normal seed unit. He should note the light brown, soft-appearing

caryopsis which can be seen with the aid of the hand lens if the light

is allowed to shine through the structure. As the lighter blowings are

examined one is often confronted with the structures which are approximately normal size but which are gray or orange and opaque.

Remove these structures from the florets for critical examination to

determine whether they are to be classified as pure seed or inert matter.

In most instances they are not seeds and therefore are included with

the inert.

Orchard grass seed often contains small slender seeds of weedy

bromegrasses which can easily be overlooked unless the analyst suspects their presence. Agropyron repens is often found in imported

samples but often only unfilled florets, or those with only anthers or

undeveloped ovaries, are present. The small thick structures occasionally found may be either weed seeds or inert matter. Orchard

grass grown in the United States is often infested with bulblets of

Allium vineale^ which are considered noxious weeds in many States.

These bulblets are frequently shriveled, dried, or broken but must be

removed and classified in accordance with the rules. They are to be

regarded as inert matter when the basal or stem end has been removed,

but if they can be identified as Allkim mneale and the basal-end portion is present they are to be regarded as weed seeds.

FESTUCA—FESCUES

Key to Illus-

^^. , j. j species, tration, Kind ofseed Page Plate

Festuca arundinacea—Tall fescue 218 IV 94

F. capillata—Hair fescue ~ 217

F. elatior—Meadow fescue ~_ 218 Yv~93

F. ovina—Sheep fescue 217

F. rubra—Red fescue 217 IV 95

F. rubra var. commutata—Chewings fescue 217 ___'

Seed unit.—Caryopsis or floret with caryopsis.

Special treatment.—All samples should be blown; one or two blowings are usually sufficient to remove all the light material from the

heavy.

Special proUems.—Individual seeds of Festuca elatior.^ F. arundincùcea., and Lolium spp. are frequently very similar in appearance and

difficult to distinguish. However, they can be identified accurately

with the use of seed keys, illustrations, and comparisons with verified

samples. The most obvious characters used in their identification are

given below.

Seeds of Lolium are symmetrical and have a thin wide callus with

a slight depression between it and the lemma. The callus is so wide

that the sides of the floret taper little but are almost parallel. There

are no teeth on the veins of the lemma, which is brown in color. The
62 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

palea has no longitudinal depression and the teeth along its edges

extend downward below its middle. The rachilla is flat with parallel

sides and has no cup at its tip.

Seeds of Festuca arundinacea are symmetrical and have a thick narrow callus with a noticeable depression between it and the lemma.

The sides of the floret taper down to the narrow callus. The color of

the lemma is brown, similar to that of Lolium. There are teeth on the

veins of the lemma, especially near the tip. The palea has a longitudinal depression and the teeth along the upper edges of the palea

extend to only about its middle. The rachilla is round with parallel

sides and has a cup at its tip.

Seeds of Festuca elatior are spindle-shaped and have a thick narrow

callus with a noticeable depression between it and the lemma. The

sides of the floret taper down to the narrow callus. The color of the

lemma is lighter brown than Loliwn and Festuca arundinacea. The

texture of the lemma is smooth whereas it is grainy in the case of F,

arundinacea and Loliuni, There are no teeth on the veins of the

lemma. The palea has a longitudinal depression and the teeth along

the upper edges of the palea extend to only about the middle. The

rachilla is round with parallel sides and has a cup at its tip.

Chewings fescue and other varieties of red fescue can be distinguished only in the bulk. The lemmas and paleas of Chewings fescue

are brighter in sheen, more purple in color, narrower in proportion

to length, and the lemmas appear to fit the caryopses neater than in

the other varieties of Festuca ruira. In contrast the other varieties

appear somewhat duller, whiter, broader, and the lemmas do not fit

the caryopses as neatly as in Chewings fescue.

Many samples of Festuca are infested with nematode galls. These

galls can be distinguished from the pure seed and are to be included

with the inert matter. The lemmas and paleas in normal Festuca

seeds fit tightly and adhere to the caryopsis making it difficult to remove the latter. Nematode infested lemmas fit loosely, become

twisted longitudinally, and the structure within can be seen through

the lemmas to be pointed rather than blunt as in the normal seed.

The galls slip out of the lemmas easily and are then seen to be either

shiny black or amber at the base graduating into black at their tips.

These are nematode galls and are included with the inert matter. If

the galls are soaked in water for about half an hour the nematodes

or eelworms will appear as a cottony mass; or they can be observed

under a microscope if crushed and placed in water on a microscope

slide.

TRITICUM, HORDEUM, PENNISETUM, SÉCALE, ORYZA, ZEA—CERTAIN CEREALS

Key to IllusKind ofseed species, tration,

Page Plate

Triticum spp.—Wheat, Spelt, Emmer XII, 201

Hordeum vulgäre—Barley 218 V, 104

Pennisetum glaucum—Pearl millet 223 VII, 149

Sécale céréale—Rye XI, 184

Oryza sativa—Rice V, 117

Zea mays—Corn

Z. mays var. everta—Popcorn

Z, m>ays var. saccharina—Sweet corn
TESTING AGRICULTURAL AND VEGETABLE SEEDS 63

Seed unit,—Caryopsis (grain) or floret with caryopsis.

Special treatment,—Blowing is an aid in determination of insect

injury. If badly broken, it is sometimes possible to remove some

broken seeds by blowing ; sifting removes fine dirt and seeds.

Special problems,—One of the commonest difficulties in making

purity analyses in this group is in determining the size of broken

fragments of pure and crop seed in relation to their original size. The

analyst should first critically examine normal seeds of the kind being

tested and note the size and shapes of normal seeds as well as the

proportion of the seed occupied by the embryo. This will serve as a

guide in determining whether more than a half seed is present in

those parts of seeds containing the embryo.

The broken seeds, whether pure seed or other crop seed, should be

removed from the sample, except those which upon first glance are

seen to be obviously more than one-half the original size. All of the

smaller^ fragments which are obviously less than one-half may be

placed in inert matter. The remainder of broken fragments should

be lined up side by side in order of relative size and each classified

on the basis of its own original size. One can determine with little

difficulty that some seed pieces are more than one-half and others less

than one-half the original size, usually leaving only a very few fragments in doubt. If it is impossible to make a positive determination

on these few remaining fragments allow one-half to be classed as pure

seed and the others as inert; or if there is an uneven number put

the larger number with the pure seed.

Seeds infested or damaged by insects present a problem somewhat

similar to the broken-seed problem, although frequently more difficult.

If the sample contains live insects they should be killed by a fumigant.

Blowing in a 3- to 4-inch blowing column will remove some of the

lighter seeds and inert material but in badly infested samples each

seed in the heavy portion will need to be examined critically to determine whether more than one-half the original seed is present.

Immature and damaged grains of some of the kinds in this group

¿ire difficult to distinguish from others. For example, shriveled grains

of wheat and rye occasionally appear very similar. The size, shape,

and position of the embryo, the fold on the seed and the color and

texture of the grain are characters which aid in distinguishing some

of these cereals.

Wheat is sometimes infested with nematodes. The infested grains

often retain a shape similar to the original but they appear somewhat

charred or burned, and there is no embryo. These nematode galls are

included with the inert matter. If there is a question as to identity

one of the galls should be soaked in water for approximately half an

hour to allow the nematodes to appear.

In this group ergot occurs chiefly in rye. There is no difficulty in

distinguishing the long thick grayish black sclerotia from the normal

grains of any of the kinds of seed in which they occur. Smut balls

are found only occasionally but they are easily identified as they

have little resemblance to seeds.

Ked rice is so named because of the color of the outer covering of

the^ rice grain. There is no problem in removing these red grains,

which are defined as noxious weeds by some State laws, in samples of
64 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

milled rice which have the lemmas and paleas removed. In unmilled

samples there is no way of identifying these red grains except to

remove the hulls hj a mill or by hand. This would be far too laborious

a process for a noxious-weed seed examination.

If a purity analysis and noxious-weed seed examination are required

of samples of unmilled rice containing red rice, it is advisable to make

the 100-gram purity analysis without regard to the red rice; then

make the noxious-weed seed examination on a 500-gram sample which

should be milled, to remove the lemmas and paleas, and examined for

the presence of noxious weed seeds.

LOLIUM—RYEGRASS

Key to Illusspecies, tration,

Kind ofseed Page Plate

Loliurn multiflorum—Italian ryegrass 220 V, 111

L. perenne—Perennial ryegrass 220 V, 110

Seed unit,—Caryopsis or floret with caryopsis.

JSpeoial treatment—Samples should be blown to remove light and

empty florets. Generally, there are only a few florets which are

difficult to interpret. The fluorescence test which is used to determine

percentages of Lolium multiflorum in samples of L, perenne is fully

described under the heading "Procedures for Determining Germination."

Special problems,—Seeds of perennial and Italian ryegrass can be

distinguished if the awns of the Italian ryegrass have not been broken

off. In commercial samples of ryegrass many awns are broken off

making it impossible to make an accurate separation on the basis of

seed characters alone. Bulk samples of the two kinds can usually be

distinguished, i. multiflorum has awns, is arched on the lemma side

so that it will not lie flat on that face, is coarser, heavier, and darker

in color than ¿. perenne, L, perenne is devoid of awns.

The percentages of perennial ryegrass and Italian ryegrass seed

in a sample can be determined by the fluorescence test more accurately

than from seed characters. All samples submitted as perennial ryefrass should be tested for fluorescence in accordance with the methods

escribed on pages 103 to 104. The following formula has been

included in the rules for seed testing for calculating the percentages

of pure perennial ryegrass after a fluorescence test has been made:

1.0526 X percent nonfluorescenceXpercent ryegrass

Percent perennial ryegrass= ^^^^^^^ fluorescence-hpercent nonfluorescence "

The following example will illustrate the substitution of test data in

the formula for a sample found to contain 98.80 percent pure seed

in the regular purity analysis :

Results of fluorescence test: Fluorescence=22.5 percent; nonfluorescence=7l.5 percent. Upon substituting the results in the formula

we have—

^'^^^l^^lln^K^'^^ = '^^^^''P == 79.10 percent of Lolium perenne in the sample.

Ergot is not uncommon in ryegrass seed. Caution must be employed to insure that ryegrass seed is not mixed with some of the larger

seeded species of fescue. Agropyron and Elymus seeds may also be
TESTING AGRICULTURAL AND VEGETABLE SEEDS 65

confused with those of ryegrass. It is advisable to remove all seeds

about which there is any question and reexamine them later, comparingthem with illustrations as well as verified samples.

Kyegrass seed is sometimes attacked by rodents as evidenced by

the absence of the lemma and back part of the seed which have been

stripped away, leaving the broken seeds in view. Some of these can

be removed by blowing but each floret in the heavier fraction must

be judged as to relative size on its own merits.

PANICUM, SETARIA, ECHINOCHLOA, ORYZOPSIS. AND ZOYSIA

Key to Illus-

„. , , j species, tration,

Kind ofseed Page Plate

Panicum antidotale—Blue panic ajass 221 VI, 122

P. ramosum—Browntop millet (see footnote, page 397) 221 Vl' 136

P. maximum—Guinea grass 221 VI, 132

P. miliaceum—Proso millet 222 Vl' 133

P. virgatum—Switchgrass 222 Vl[ 138

Setaria itálica—Foxtail millet 229 Xl| 180-183

Echinochloa crusgalli VSLT. frumentacea—Japanese millet 214 iv' 78

Oryzopsis hymenoides—Indian ricegrass V, 118

0. miliacea—Smilo v' 119

Zoysia japónica—Japanese lawngrass 231 XIl! 202

Z. matrella—Manila grass 231 XII, 203

Seed unit,—Caryopsis; floret or spikelet with a caryopsis.

Special treatment,—All samples should be blown to remove the light

chaff. The seed unit in all these genera have thick opaque coverings

which make the determination of pure seed by vision alone impossible.

In most samples it is advisable to make several blowings, being sure

that the air pressure is strong enough to remove all inert florets and

spikelets from the heavy portion. Examine the heaviest fraction

first and work down through the lighter blowings. Samples contammg fine dirt and weeds should be sifted.

Special problems.—One of the principal problems in this group

is the separation of florets and spikelets with seeds from those which

are empty. Separate a few of the seeds from the heaviest fraction on

the basis of their resistance to the pressure of pointed forceps. When

a few of these have been separated open the lemma and palea of a few

to determine whether the floret or spikelet should be considered pure

seed or inert matter. It will be necessary to open only a few to establish confidence in the operation.

^Setaria itálica^ foxtail millet, contains two important varieties:

German millet; and Common millet. These two varieties of millet

hybridize readily in the field. Hybrid seeds cannot be definitely

identified as to variety. Therefore, any variety separation on the seeds

of millet must be of a negative nature. The presence of tubercled

seeds m Common millet or smooth seeds in German millet suggests

that the sample is not pure as to variety. Since an accurate separation

to determine the percentages of varieties cannot be made such a separation cannot be used for labeling purposes. However, the test has

some value in seed control work.

^ Samples of Setaria itálica often contain seeds of Setaria viridis and

Setaria verticillata. These seeds are smaller and rougher than foxtail

millet and are usually mottled.

The florets of Japanese millet and barnyard grass (^E, crusgalli)

might easily be confused but the spikelets are readily distinguished by
66 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

the awns and the presence of teeth on the glumes of barnyard grass.

The florets of barnyard grass are more slender, with the widest point

about midway of the floret, whereas the widest pointin Japanese millet

is below the middle,

PHLEUM, ERAGROSTIS, AND SPOROBOLUS

Key to niuftspecies, tratîon,

Kind ofseed Paffe Plate

Phleum. pratense—Timothy """;« T-U' QC^

EragrosHs curvula—Weeping lovegrass 216 IV, 88

Sporoholus cryptandrus—Sand dropseed 231 XII, 197

Seed unit.—Caryopsis or floret with caryopsis.

Special treatment,—Blow samples which may contain empty or

immature florets. Sift to remove fine dirt and seeds.

Special problems,—The identification of Sporobolus cryptandrus

may be difficult, especially in samples containing seed of S. contractus.

Seeds and florets of S. cryptandrus are very similar to those of S,

contractus which occur in a much more limited area. Timothy seed

may retain the lemmas and paleas (grains in the hull or chaff) or may

be free of them. Seedsmen sometimes desire to know the percentage

of hulled seed in lots of timothy. This separation should be made

from the pure seed component of a regular purity analysis, using the

entire sample. Ordinarily, there is no difficulty in separating the entire pure seed portion (approximately 2 grams) ; by doing so calculation of the results is simplified.

ALOPECURUS, ANTHOXANTHUM, ARRHENATHERUM, CHLORIS, HOLCUS, AND

MELINIS

Key to lllusspecies, tration,

Kind ofseed ^«?« ^^ß^^"

Alopecurus pratensis—Meadow foxtail 202 I, 22

Anthoxanthum odoratum—Sweet vernal grass 204 II, 33

Arrhenatherum elatius—Toll meadow oat grass 205 II, So

Chloris gayana—Rhodes grass 212 III, 60

Holcus lanatus—Velvet grass V» 102

Melinis minutiflora—Molasses grass V, 114

Seed i^mY.—Caryopsis ; floret or spikelet with caryopsis.

Special treatment—IÎ the sample lodges in the blower tube, blow

smaller portions and combine the separations of the blowings ; or use

a larger, 3- to 4-inch, blowing tube. . .ic i

Special problems,—Determination of pure seed is difficult as the

lemmas and paleas are so thick and translucent that the presence or

absence of a caryopsis cannot be ascertained without the use of pressure or reflected light. Make several separate blowings—until all

florets with only anthers or undeveloped ovaries are removed from

the heavy portion. Begin with the heaviest blowing first, removing,

for critical examination, those caryopses whose value cannot be determined with certainty on the basis of appearance and "feel" of the

florets. . When itis necessary to identify naked caryopses, compare them with

caryopses removed from known samples.

Little, if any, seed of molasses grass and Rhodes grass is prodiiced

in this country. The imported seed is usually of low purity. The
TESTING AGRICULTURAL AND VEGETABLE SEEDS 67

light inert matter must all be blown off or the purity analysis will

require critical examination of each floret involving more time than

is justified.

The spikelets of Chloris gayana normally consist of one fertile and

one sterile floret but occasionally both are fertile. Attached sterile

florets are not removed in the purity test. Single florets are not

usual. In examining the blowings be sure to critically examine both

upper and lower florets for pure seed. Some help can be gained by

using the diaphanoscope, but this test, more than any other, requires

a great deal of interpretation by "feel." Use caution with respect

to the amount of pressure exerted on the florets or the seed may be

injured, resulting in low germination. The presence or absence of a

caryopsis can be determined most accurately by stroking the spikelet

from the callus to the tip with the edge of the spatula, forceps, or

scalpel and not by exerting pressure with the points of these

instruments.

Seeds of this group likely to be confused with other species include

the following :

Alopecurus pratensis with seeds of Alopecurus geniculatus;

AntJioxanthum odoratum with seeds of Anthoxanthum aristatum;

Chloris gayana with seeds of Chloris virgata and Chloris divaricata ;

Holcus lanatics with seeds of Holcus mollis.

BUCHLOË—BUFFALO GRASS

Kind of seed

BuGhloë dactyloides—Buffalo grass.

Description on page 208 ; plate II, 45.

Seed unit.—Bur, floret, or caryopsis.

Special treatment.—^If sample contains small incidental seeds and

dirt, sifting eliminates some of the hand work.

Special problems.—None except possible broken caryopses in

processed seed.

PGA—BLUEGRASS

Key to Illusspecies, tration,

Kind ofseed Page Plate

Poa annua—Annual bluegrass : 226 VIII, 159

P. arachnifera—Texas bluegrass 226 VIII, 161

P. bulbosa—Bulbous bluegrass 227 VIII, 163

P. compressa—Canada bluegrass 225 VIII, 164

P. nemoralis—Wood bluegrass 226 IX, 166

P. nevadensis—Nevada bluegrass 226 IX, 167

P. pratensis—Kentucky bluegrass 225 IX, 169

P. trivialis—Rough bluegrass 225 IX, 170

Seed vmit.—Caryopsis; floret or spikelet with caryopsis and in

Poa bulbosa the bulblet.

Speöial treatment.—There are two basic procedures accepted for

testing Kentucky bluegrass and Canada bluegrass seed for purity.

The standard or generally accepted procedure consists of separating

the sample into several fractions with a seed blower which may or may

not be standardized, and working the sample normally.

Make several blowings until the heavy portion contains no inert

florets of bluegrass. Examine the heaviest portion first to get acquainted with the feel and appearance of normal pure seed. Examine

each blowing beginning with the heaviest. If there is question as to
68 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

whether some florets are pure seed or inert matter examine a few by

"feel" or with a diaphanoscope ; then open these and determine their

classification on the basis of development of the caryopses. Examine

each blowing for pure seed florets, beginning with the heavy fraction

and continue until one blowing is found with no pure seed. It is safe

to assume that any lighter blowings would contain no pure seed

florets. Examine all blowings for other crop seeds and weed seeds,

and the residue for inert matter, other crop seeds, and weed seeds.

Multiple florets of bluegrass are not separated.

The other basic procedure consists in blowing the samples in seed

blowers which have been standardized and calibrated for these kinds

of seed. The two detailed methods which are discussed below are in

use.

Iowa method,—By the Iowa method a sample, limited in size from

0.950 to 1.050 grams, is blown in an Iowa blower at four predetermined

gate openings. The portions which collect in the trap from the two

lowest blowings are examined only for crop and weed seeds. Any

pure seed florets in these portions are considered inert matter. The

portions from the two highest blowings are examined for pure seed

florets, weed and crop seeds. The portion remaining in the cup is

examined for crop and weed seeds and inert matter other than bluegrass florets. All bluegrass florets in this portion are regarded as

pure seed.

The four components are weighed and the percentages calculated

as in any other purity analysis.

If in examining the two blowings the analyst finds mainly inert

florets he should again blow the heavy portion at one interval higher

until the blowings contain some pure seed florets. If he should find

mainly pure seed florets in these two blowings he should recombine the

inert matter with thé heavy fraction and blow again, starting at a

point low enough to obtain some inert florets.

Either of the above conditions indicates that the blower is improperly calibrated. In such an event the blower should be calibrated by

using the stained sample provided for this purpose. The blowings

made above or below the scheduled openings should serve as an indication of the approximate starting point in making the calibration.

Ottawa method,—^The Ottawa method is based on the Ottawa seed

blower and eliminates any personal selection of florets in making the

purity separation. A manometer on the Ottawa blower serves to

indicate and regulate the velocity of the current of air used to separate

the inert and the pure seed florets. The key manometer reading

(K. M. K.) is that point on the manometer which indicates a current

of air sufficient to separate the inert from the pure florets in a given

kind of seed. The gate opening required to get a given K. M. E. may

differ, depending on atmospheric pressure, electric current, or other

outside factors but the manometer registers the current of air that is

actually being driven to the seed; therefore, the pressure remains

constant for a given cup or tube, within certain temperature limits.

Since exposure of the manometer to direct sunlight will interfere

with the calibration in determining the K. M. R., the blower should

be kept out of direct sunlight and areas where the temperature may

fluctuate considerably.

The manometer fluid should be at zero and the screen should be

thoroughly cleaned before starting the motor. After the motor has
TESTING AGRICULTURAL AND VEGETABLE SEEDS 69

been warmed up for 10 minutes the indicator on the manometer should

be placed over the K. M. E. Be sure there are no seeds or dirt under

the edge of the cup. With tube and cup in place, switch on the motor

and open the gate slowly until the lower edge of the meniscus of the

red liquid in the manometer tube reaches the indicator. The meniscus is the concavely curved upper surface of the liquid in the tube.

When this has been done switch off the motor, place the sample in

the cup, and with the tube in position in the cup, switch on the motor

and blow the sample for 5 minutes after the first floret goes over. All

bluegrass florets remaining in the cup are regarded as pure seed and

all which are blown into the trap) are considered inert matter. The

material in the cup must be examined for crop seeds, weed seeds, and

inert matter other than bluegrass florets. The portion in the trap is

examined for crop and weed seeds but not for pure seed. The four

components are then weighed and the percentage of each component

is determined by the usual method.

Both the Iowa and Ottawa methods have value and can be used for

some purposes but there are some dangers associated with their use.

Some samples of Kentucky bluegrass seed have been found to contain relatively high percentages of florets in which the caryopses have

developed abnormally owing to insect injury. Because these structures are as heavy as filled florets they are not removed by using either

of the standardized blowing techniques but will be left with the pure

seed. These structures are inert matter because the flowers were

blighted to the extent that seeds did not form.^ Unless the analyst is a

very careful worker it would not be at all unlikely to read the dial incorrectly and blow an occasional sample too strongly or not strongly

enough, thereby giving incorrect results. Also, unless the screens are

clean the current of air passing through the cup and tube will not be

uniform for a given valve or gate opening.

In commercial plants where a test on bluegrass is made to test the

efficiency of cleaning processes these methods save much time. In

laboratories making tests for labeling purposes or for control work

these methods can be used with safety only in the hands of careful and

experienced analysts. In testing for the latter purposes the samples

should be examined carefully for inert florets in the pure seed and

conversely for the presence of pure seed florets in the inert matter.

A few empty or filled florets out of place is of little significance but

these out-of-place florets must remain within a reasonable limit.

Eegardless of the method used, the analyst must examine the pure

seed carefully in order to determine whether seeds of other species of

Poa may be present. Fortunately, the common weedy species are typical enough so they may easily be removed from the entire quantity

tested. Some of the crop species are not always so typical; therefore,

when more than one crop species of bluegrass is present a test to

determine the proportions of the different species is made on a smaller

sample of seed. If the sample is to be tested for germination it is

advisable to use 800 or 1,000 seeds for the separation, because, if the

sample is a mixture of species, a 400-seed test would yield an insufficient number of seeds for the germination test. The portion for this

test is taken indiscriminately from the pure seed fraction (all species

of Poa) of the regular purity analysis after it has been weighed and

the percentages of the four components determined. The naked
70 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

caryopses are included in this portion but their identity cannot be

determined.

The following example illustrates the methods for determining the

percentages of kinds found in a sample with 88.09 percent of Poa spp. :

Of 1,000 seeds examined—

Percent of

Wt. in gm. Percent sample

Poa pratensis 0.1209 56.55X88.09 = 49.81

P. compressa . 0925 43. 26X88, 09 = 38. 11

P. spp. (naked caryopses) . 0004 . 19 X 88. 09 = .17

Kentucky bluegrass matures its seed earlier than does Canada bluegrass; consequently, it is usual to find Kentucky bluegrass seed in

samples of Canada bluegrass but seeds of Canada bluegrass do not

often occur in samples of Kentucky bluegrass unless they have been

placed there intentionally.

Eough bluegrass, Poa trivialis^ is generally not grown for seed in

this country and it is seldom that it is found as an incidental seed in

other crops except in lawn grass or pasture mixtures. It can be noted

in bulk seed from the way the florets cling together by the tufts of

hair at the callus. The bulk is a more golden brown than Poa

pratensis.

Annual bluegrass seed, Poa annua^ is occasionally found in any of

the other bluegrasses, although seldom in large numbers. It can be

classed as either a crop or a weed.

Seed of Fowl bluegrass, Poa palustris^ is frequently found in domestically grown bluegrass seed. It is usually regarded as a weed seed

unless labeled and sold as a crop. It is easily recognized in a sample

because of its slim delicate appearance, light at the callus, orange at

the tip of the lemma, and with a rachilla longer and more slender

than the other common species of bluegrass.

In the development of bulbous bluegrass, Poa huTbosa^ the florets

are converted into bulblets. The bulblet is the so-called seed unit.

Each bulblet is surrounded by bracts and it is necessary to determine

the presence or absence of a bulblet in the same manner as that used

in determining the presence or absence of a caryopsis.

SORGHUM

Key to Illusspecies, tration,

Kind ofseed Page Plate

Sorghum vulgäre—Sorghum 230 XI, 188-193

S. vulgäre var. technicum—Broomcorn 230 XT, 194

S. sudanense (S. vulgäre var. sudanense)—Sudan grass 230 XI, 186

S. halepense—Johnson grass 230 XI, 185

Seed unit,—Caryopsis or spikelet with caryopsis.

Special treatment,—It is advisable to blow most samples of sorghum

seed unless it can be determined at a glance that the sample contains no light material which may be blown off. Blow Sudan grass

and Johnson grass seed long enough to remove all light material from

the sample. Sudan grass should be sifted to remove Johnson grass

seed.

Special prohlems.—The positive identification of varieties of Sorghum from caryopses or spikelets alone can usually be made only by

specialists in that group and this is limited to certain varieties. With

training and practice the analyst can make some varietal separations

with reasonable accuracy. Only partial separations can be made on
TESTING AGRICULTURAL AND VEGETABLE SEEDS 71

some samples in which case certain seeds can be identified, but there

will be other seeds which cannot be positively identified.

The varietal separation should be made on at least 400 seeds taken

indiscriminately from the pure seed fraction of the regular purity

analysis.

The percentages of varieties in a test with a pure seed percentage

of 98.80 percent are determined in the following manner :

Of 400 seeds examined—

Percent of

Wt. in gm. Percent sample

Honey- 8.552 93.84X98.80 = 92.71

Sumac .301 3.30X98.80 = 3.26

Undetermined .218 2.39X98.80 = 2.36

Black Amber .043 .47X98.80 = .47

Samples of Sudan grass often contain seeds of Johnson grass.

Sieves made with %2-inch and i^e-i^^^l^ mesh screen will allow single

spikelets to go through but they will hold back any double spikelets.

The spikelets caught in the pan should be examined for naked caryopses and smaller spikelets of Johnson grass. Those caught in the

bottom sieve should be examined for normal size, single spikelets.

Check the top sieve for multiple spikelets of Johnson grass.

The glumes of Johnson grass are generally dark mahogany or reddish brown in color but there are some straw-colored seeds. The two

rachillae often remain on the spikelet, each one having a little cup at

its tip. The union of the pedicel and the spikelet is articulated, allowing the spikelets to break off clean with no remnants of the pedicel

as is common in Sudan grass. Johnson grass spikelets are much

neater and trimmer in appearance than those of Sudan grass.

Identification can generally be made from the characters exhibited

by the spikelets but if there is doubt the grain should be removed.

This can be done, without injuring the glumes, by holding the spikelet between the thumb and forefinger of the left hand and slipping a

pointed knife or scalpel between the glume and grain; then gently

lifting and pulling the grain out. The glumes should not be destroyed as they are often needed, in combination with the characters

of the grain or caryopsis, to make a positive identification.

In making a purity analysis of either Common or Sweet Sudan

grass, those seeds which can definitely be identified as Sorghum vulgäre are removed and included with other crop seeds. Seeds of most

varieties of Sorghumi run larger and are more nearly spherical in

shape than those of Sudan grass. Glumes of most varieties of Sorghum seed are spreading at the tip and the grain seldom protrudes.

When unidentified seeds are found in Common Sudan grass the following note should be included on the record: "Included with the

pure seed are some seeds which appear to be Sorghum Sudan grass

hybrids." In Sweet Sudan grass samples these would be classified

in the varietal separation on the basis of color.

Since most available seed supplies of Sweet Sudan grass contain

admixtures of Common Sudan grass and because it is impossible

to make a complete, accurate separation of the two, based on seed

characters alone, a special test designed to achieve uniformity, as well

as reasonable accuracy has been developed.

The sienna color in the glumes of Sweet Sudan grass is said to have

been bred into it intentionally in order to distinguish it from Com-
72 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

mon Sudun and Johnson grass. Since the sienna color is a recessive

character all seeds having this glume color are pure Sweet Sudan grass

seeds.

The black color in the glumes of some Common Sudan grass seeds

is not found in the glumes of Sweet Sudan grass. All seeds having

this glume color are Common Sudan or hybrids. Straw-colored

glumes may appear in some lots of pure Sweet Sudan grass but this

glume color is also found in Common Sudan grass. Straw-colored

seeds, then, may be either Sweet or Common Sudan grass.

Seeds with red, chocolate, or mahogany glumes are interhybrids

and are not included with the pure Sweet Sudan grass seed. Since

seeds with straw-colored glumes may be found in both Sweet and

Common Sudan grass, some adjustments must be made if uniformity

is to be achieved. The procedure for making varietal separations of

Sudan grass seed allows as much as 5 percent of the seeds with strawcolored glumes to be considered as Sweet Sudan grass. In the varietal

separation only Sudan grass seeds with sienna-colored glumes and

up to and including 5 percent of the seeds having straw-colored

glumes are to be considered as Sweet Sudan grass seeds. All other

seeds are to be classed as Common Sudan grass and hybrids.

After the regular purity analysis has been made at least 400 seeds

(excluding naked caryopses or grains) shall be taken indiscriminately from the pure seed portion. These 400 or more seeds are separated on the basis of glume color alone into : (1) Sienna; (2) Straw;

and (3) Black and Interhybrids.

The Sienna group shall include seeds varying from those completely

sienna-colored to others with only a spot of sienna on some part of a

glume, frequently at its base. (See exception under the 'Tnterhybrid

group" below.) Sienna includes glume colors of various sienna hues

such as sienna with chocolate cast, and sienna with a rose cast, as well

as seeds with golden-colored glumes. Seeds which are essentially

purple but have a sienna spot are included in this group.

The Straw group covers all hues from pale straw (having a

"washed-out" appearance) to tan, including hues with a suggestion

of sienna or red but no definite spot of sienna. Seeds with purple on

all or part of the glumes shall be classified in this group.

The Black and Interhybrid group includes all seeds having the

following color characteristics : Glossy black ; dull black ; black with

red cast; all seeds with some definite black on the glumes ; typical red ;

dark red ; chocolate ; and mahogany—even though any in this group

may contain streaks or spots of sienna. For standard color chart

and color photographs of Sudan grass, see Testing Sweet Sudan

Grass Seed for Purity and Germination—Instruction No. 959

(FSAct)—issued by Grain Branch, Production and Marketing Administration, U. S. Department of Agriculture, Washington 25, D. C.

The following example indicates the manner of determining the

percentage of Sweet Sudan grass in a sample containing 98.50 percent

of Common and Sweet Sudan grass seed :

Percent to be

Wt. in gm. Percent Percent in sample reported

Sienna 3.255 88.50X98.50 = 87. 17-f-5 = » 92. 17

Black and Interhybrids . 173 4. 70X98. 50 - 4. 63 = ^ 4. 53

Straw .250 6.80X98.50 = 6.70-5 t- 2 1. 70

' Sweet Sudan grass.

2 6.33 (4.63+1.70) percent Common Sudan grass and Hybrids to be reported.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 73

If there is less than 5 percent of straw-colored seeds in the separation the entire percentage is included with the Sienna leaving nothing

to add to the Common Sudan and hybrid group.

The Common Sudan and hybrid group percentage should be reported separately if it constitutes more than 5 percent of the sample.

If that group constitutes less than 5 percent of the sample it may

either be included with the percentage of other crop seeds or reported

separately.

LEGUMINOSAE (LEGUME OR PEA FAMILY)

ARACHIS, CICER, GLYCINE, LUPINUS, PHASEOLUS, PISUM, STIZOLOBIUM, AND

VIGNA—LARGE-SEEDED LEGUMES

Key to niuS'

species, tration,

Kind ofseed PaOß -P^a^ß

Avachis hypogaea—Peanut

Cicer arietinum—Chickpea 239 XIX, 366

Glycine max—Soybean 241 XIX, 377

Lupinus albus—White lupine 246

L. angustifolius—Blue lupine 246 XX, 396

L. Zwie-ws—Yellow lupine 246 XX, 397

Phaseolus angularis—Adzuki bean 248 XX, 410

P. aureus—Mung bean 248 XX, 411

P. coccineus—Runner bean

P. lunatus var. macrocarpus—Lima bean

P. vulgaris—Field or garden bean

Pisum sativum—Garden pea

P. sativum var. arvense—Field pea 249 XXI, 412

Stizolohium deeringianum—Velvet bean 249 XXI, 415

Vigna sesquipedalis—Asparagus bean 1-

V. sinensis—Cowpea. 257 XXIII, 467, 468

Seed unit,—Seed, except in peanut in which it may be either a seed

or a pod with at least one seed.

Special treatment.—Sift samples containing broken seeds to separate the broken cotyledons from the whole seeds. Small portions

of samples which are badly infested with insects can be blown in a

blower with a 3- to 4-inch tube or column.

Special problems.—Seeds of legumes with the seed coats entirely

removed are classified as inert matter. Seeds with part of the seed

coat still attached are classified as pure seed or other crop seed, as the

case may be. In some rare instances there are such small portions

of the coats left on the seeds that it is impossible to identify them

as pure or foreign seed. Such structures are included with the inert

matter.

Each broken seed must be individually judged to determine whether

the remaining portion is to be classified as a seed or as inert matter.

If the broken fragment contains one cotyledon with the seed coat

attached, but does not contain the embryonic plant, it should be classed

as inert matter. If it contains a portion of the seed coat, one cotyledon

and the embryo, judgment will have to be exercised to determine

whether it is more than half its original size and should be regarded

as a seed, or is half or less the original size and should be included with

the inert matter.

Insect-infested seeds are often very difficult to classify. Frequently,

a single seed has been attacked by more than one insect. If the insects

have broken through the seed coats the holes are obvious and the relative extent of injury can be determined by rotating the seeds. If tho
Percent in

Percent sample

86.58X99.64 = 86.27

13.42X99.64 = 13. 37

74 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

insects have not broken through the coats the infested areas will look

as though they were decayed and oily, often having dust particles

clinging to the spots, or the entire seed may have a decayed oily appearance. The amount of infestation can be determined by rolling

the seed between the thumb and forefinger or by piercing the coat

with sharp-pointed forceps at each point of infestation, thus determining the relative amount of destruction at each point.

Complete and accurate varietal separations of cowpeas, soybeans,

beans, and peas can be made only for a few varieties in each kind. If

varietal identification is contemplated the analyst must learn the limits

of identification for the varieties grown in the areas for which the

tests are being made. The varietal separations should be made on

at least 400 seeds taken indiscriminately from the pure seed portion

of the regular purity analysis.

The method of calculating the results of a 400-seed separation is

illustrated by the following example showing soybeans with a pure

seed content of 99.64 percent :

Of 400 seeds examined—

Wt. in gm.

Mammouth Yellow 141. 37

Ogden 21. 91

CROTALARIA, AND LEGUMES OF LIMITED USE

Key to Illusspecies, tration,

Kind ofseed Page Page

Crotalaria intermedia—Slender-leaf crotalaria 240 XIX, 369

C. júncea—Sunn crotalaria 240

C. lanceolata—Lance crotalaria 240 XIX, 370

C. spectahilis—Showy crotalaria 240 XIX, 372

C, mucronata (C. striata)—Striate crotalaria 240

Desmodium tortuosum—Beggarweed 241 XIX, 375

Lathyrus hirsutus—Rough pea 243 XIX, 382

Onobrychis viciaefolia—Sainfoin 248 XX, 407

Pueraria thunhergiana—Kudzu 249 XXI, 413

Seshania exáltala—Sesbania 249 XXI, 414

Seed unit,—Seed, except in Desmodium tortuosum' and Onohrychis

viciaefolia in which it is either a seed or a pod containing a seed.

Special treatment,—Samples should be sifted to remove dirt and

foreign seeds and blown to remove the light insect-infested seed.

Special prohlems,—Broken seeds must be judged individually in

order to properly classify them in accordance with the one-half seed

rule.

For information regarding the classification of insect-infested seeds

in this group refer to the treatment on the genus Trifolium^ pages

77 to 78.

LESPEDEZA

Key to Illusspecies, tration.

Kind ofseed Page Plate

Lespedeza cuneata (L. sericea)—Sericea or Chinese lespedeza. _ 244 XX, 389

L. hedysaroides—Siberian lespedeza 244

L. stipulacea—Korean lespedeza 244 XX, 388

L. sínaía—Common, Kobe, and Tenn. 76 lespedeza 244 XIX, 386, 387

Seed unit,—Seed, or pod with seed.

Special treatment,—Sifting is an aid in removing dirt as well as

some incidental seeds. Blowing of samples containing pod fragments
TESTING AGRICULTURAL AND VEGETABLE SEEDS 75

or other lightweight inert matter lessens the amount of hand picking

or manual work.

Special problems,—Lespedeza striata and Z. stipulacea can be separated with accuracy whether or not the pods are present. In bulk

the pods of L. striata are grayish brown whereas those of L, stipulacea

are reddish brown. The pods and calyx of Z. striata are pointed and

rather loose fitting and those of Z. stipulacea are blunt at the tips and

rather close fitting. The seeds of Z. striata are generally mottled,

purple and green, with the scar in a small notch at the end of the seed.

Z. stipulacea is usually plain purple although mottled seeds are occasionally found; the seed has no notch near the tip and the scar is

nearer the end of the seed than in Z. striata.

Seeds of Kobe and Common lespedeza can be separated but not with

complete accuracy in all cases. In general, seeds of Kobe are larger

and the pods grayer and larger than in the Common variety. The

small seeds of Kobe probably cannot be accurately separated from the

large seeds of Common.

LOTUS—TREFOIL

Key to lllusspecies, tration,

Kind ofseed Page Plate

Lotus corniculatus—Birdsfoot trefoil 245 XX, 391

L. uliginosus—Big trefoil 245 XX, 394, 395

Seed unit,—Seed.

Special treatment,—Siftto remove dirt and small foreign seeds.

Special problems,—Some samples contain some seeds of alfalfa and

red clover. Small seeds of Galium are often present. Seeds of birdsfoot trefoil have a variety of shapes. In general, they are plump,

round, and dull brown with purplish mottling but it is not unusual to

find some seeds that are almost cylindrical and others roughly heartshaped, faintly resembling red clover in outline.

Seeds of big trefoil are smaller and greener than those of birdsfoot trefoil. A few (usually shriveled) seeds of the two species may

be indistinguishable; if so,"the following note should be placed on

the record card and report : ''Certain seeds of Lotus corniculatus and

Z. uliginosus are indistinguishable."

If the sample is infested with insects follow the same procedure as

described for Trifolium,

MELILOTUS—SWEETCLOVER AND SOURCLOVER

Key to Illus-

^^. , , , species, tration,

Kind ofseed Page Plate

Melilohis alba—White Blossom sweetclover ^ 247 XX, 404

M, indica—Sourclover ^ 248 XX,' 406

M, officinalis—Yellow Blossom sweetclover 247 XX) 405

Seed unit,—True seed or pod with seed.

Special treatment,—Samples can be sifted to remove the fine dirt

and small incidental seeds or blown to remove fragments of pods or

light dirt.

Special problems,—Seeds of alfalfa and red clover are sometimes

found in samples of sweetclover. Only a few of these will be difficult

to distinguish. Alfalfa seeds usually have one face that is angled.

957116—52 6
76 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Sweetclover seeds are rough in texture as contrasted to the smooth seed

coats of red clover and alfalfa.

Mottled seed in a sample of white blossom sweetclover indicates that

there is present seed of yellow blossom sweetclover. The amount of

mottling in a sample of yellow blossom sweetclover varies from only

a few percent to as much as half the sample. It has been determined

from greenhouse and field plantings that in most samples there are

about four times as much yellow blossom sweetclover present as

mottled seeds. Thus, the present rule provides that each percent of

mottled seed present will be construed as representing 4 percent of

yellow blossom sweetclover. Hence, 1.3 percent of mottled seed indicates that there are four times that amount (5.2 percent) of yellow

blossom sweetclover seeds in the sample, making the sample a mixture

of white and yellow blossom sweetclover.

If the sample is submitted under the name "sweetclover" it is unnecessary to make a test for mottled seed. If submitted as yellow blossom sweetclover and containing no mottled seeds, examine the sample

carefully for large, light yellow, plump, rough-coated seeds which are

recognizable as seeds of white blossom sweetclover. However, a detailed separation of the two species cannot be made. The fact that

there are no mottled seeds to indicate yellow blossom sweetclover

should be noted and that there are seeds which appear to be white

blossom sweetclover. Only a growing test can provide actual percentages.

When a sample is submitted as white blossom sweetclover a test to

determine the percentage of mottled seeds should be made. A hand

lens is essential for an accurate separation and a stereoscopic microscope for detection of some of the more obscure markings.

True mottling should not be confused with spotting by red and

purple abrasions or lesions. The latter cannot be regarded as mottled ;

this condition has no effect on germination.

Mottling of the seeds appears as small irregular purple spots which,

when seen under magnification, suggest a spot of color shining

through frosted glass. The lesions are generally larger, more clearly

outlined, and a brighter reddish purple in color. A stereoscopic

microscope is often necessary to distinguish these differences.

Because the seeds are rough and are sometimes considerably rubbed

before they are received for test there may be small dark areas which

appear to be mottled but which upon closer examination are found

to be only the protuberances on the coat rubbed smooth, making them

appear darker green than the remainder of the seed. Since these

spots are not a different color they must not be classed as mottled.

In a mottled seed test of Melilotus aTba^ the percentage of mottled

seed is determined in the following manner :

Weight of mottled seed , , ,i , j

^^^ . , ,—-^ -. 7-=percent mottled seed. Weight of entire sample

Example: wt.ingm.

Pure sweetclover 4. 9291

Other crop, inert, and weeds . 1004

Mottled seed 1. 0421

Substituting we have—

í'^o^í ^"^• =20.72 percent mottled seed. 5.0295 gm.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 77

Since each percent of mottled seed is construed to represent 4 percent

of yellow blossom sweetclover the 20.72 percent X 4=82.88 percent

yellow blossom sweetclover. Then, 98.00 — 82.88 = 15.12 percent of

white blossom sweetclover.

ALYSICARPUS, MEDICAGO, AND TRIFOLIUM

Key to Illusspecies, tratmi,

Kind ofseed Page Plate

Alysicarpus vaginalis—Alyce clover 238 XVIII, 356

Medicago arabica—Spotted bur clover 246 XX, 398

M. hispida—Bur clover 246 XX, 399

M. lupulina—Blsick medic 247 XX, 400

M.sativa—AlfâUâ 247 XX, 402

Trifolium alexandrinum—Berseem clover 254 XXII, 446

T. duhium—Suckling clover (small hop clover) 252 XXI, 427

T. /raofî/erwm—Strawberry clover 253 XXII, 437

T. glomeratum—Cluster clover 252 XXI, 419

T. hybridum—AMke clover 253 XXII, 439

T. incarnatum—Crimson clover 254 XXII, 448

T. lappaceum—Lappa clover 253 XXI, 429

r. praiense—Red clover 253 XXI, 431

T. procumbens—Large hop clover 252 XXI, 428

T. repens—White and Ladino clover 253 XXI, 432

/Seedunit,—Seed; pod with seed, or "bur."

Special treatment,—The separation will be made easier if the sample

is sieved. Mixtures should also be sieved to help separate the species,

if there is a differential in size. Insect-infested samples should be

blown to remove the light inert matter.

Medicago hispida and M, arahica in the bur are difficult to divide

and can probably be sampled fairly well by the halving method.

Samples that show evidence of insect infestation should be blown

at high enough pressures to remove the infested seeds. This may

remove some pure seed, but it will reduce the amount to be examined

critically for insect infestation.

Special problems,—^Alfalfa and red clover seeds are often infested

with an insect known as chalcid fly. The chalcid fly deposits its egg

in the ovary of the flower where the ^gg develops along with the

ovary which provides food for the developing insect. When the

seed is harvested, the insects will be in all stages of development from

the ^gg to the mature fly. Infested seed is considered inert matter

only when half or more than half of the original seed has been

destroyed. The infested seed can be removed by blowing but in using

enough air to remove all the infested seed some pure seed will also

be removed. This makes it necessary to separate the infested seed

from the pure seed in this portion.

The infested seeds are generally swollen and appear decayed, their

color lacking the lifelike appearance of normal seeds. An analyst

unfamiliar with these infested samples can easily detect those seeds

from which the adult fly has emerged and left a hole in the seed coat.

It may be more difficult to learn to recognize those seeds with the

seed coat unbroken. Until the analyst becomes completely familiar

with the nature of the infestation, all seeds that appear as though

they might be infested should be removed and gently squeezed with

the forceps. If the major portion has been eaten away the seed will

collapse easily ; these should be included with the inert matter. Those

which resist this pressure should remain with the pure seed. The
78 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

analyst will soon learn to recognize the insect-infested seeds by visual

examination alone or by applying pressure to only a few questionable

seeds in a sample.

The separation of insect-infested and insect-damaged seeds from

noninfested seeds can often be facilitated by use of a seed blower.

The blower should be set to remove the infested seeds and only the

smaller and lighter of the noninfested seeds. The "blowings" must

then be examined in accordance with the usual procedure.

Broken seeds must be judged individually to determine whether the

seed is more than half its original size, and is to be regarded as a

seed ; or half or less than half its original size, and to be included

with the inert matter. The irregular shape of the seeds makes this

determination more difficult. Those fragments which are difficult

to classify should be placed alongside unbroken seeds of the same

kind, size, and shape as a means of comparison.

Certain seeds of several of the species are difficult to identify. As

each sample is tested the analyst should recall those kinds of seeds

of similar appearance which might be present. For example, red

clover may contain seeds of berseem clover, sweetclover, alfalfa, or

weedy species of TrifoUum^ which are distinguishable but similar

enough to be overlooked unless the analyst is aware of their potential

presence.

Thin green, or shriveled brown seeds, frequently found in alfalfa,

are included with the pure seed and take their place among the others

in the germination test provided they are more than one-half their

original size. Low-quality seed stocks often contain many of these

immature seeds.

Some seeds of alfalfa, sweetclover, and red clover are difficult to

distinguish. Alfalfa is borne in a coiled pod containing many seeds,

whereas sweetclover and red clover are borne in single-seeded pods.

Alfalfa seeds usually have one face with an angle which has probably

been produced by the seeds crowding against one another in the pod.

Sweetclover and red clover seeds are more symmetrical and rarely

have a distinct angle. Where several analysts are working together

it is desirable to check each other's identifications on these seeds, until

a high degree of confidence is attained.

The identification of seeds of the bur clovers may be difficult. In

addition to the keys and illustrations of bur clover given in this

manual Isely {29) has described and illustrated seeds of these species.

Mixtures of alsike, white, suckling, cluster, large-hop, and other

clovers often occur and the sample may contain weedy species of

Trifolium such as T, arvense and T, striatwn. These seeds are distinguishable, with the exception of a few immature or shriveled darkened ones. Throughout the test, the analyst should call to mind as

many of these kinds as possible and maintain constant vigilance for

them as he works through the sample.

If the sample contains a few seeds which are indistinguishable, a

statement along the line of the following should be affixed to the record and report. "Certain seeds of Trifolium and T,

are indistinguishable."

Some insect infestations, such as occur in seeds of white clover, are

manifested by open holes. The determination of the relative amount

of destruction can be made by careful visual examination, being sure

that both faces of the seeds are examined for holes made by the insects.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 79

VICIA—VETCHES AND BROAD BEAN

Key to JUus-

^,, , , . species, tration,

Kind ofseed Page Plate

Vicia angustifolia—Narrowleaf vetch 257 XXIII, 463, 464

V. articúlala—Monantha vetch 257

V. atropurpúrea—Purple vetch 257 XXII, 459

V. dasycarpa—Woollypod vetch 257 XXIIlj 466

V. faha—Broad bean

V. pannonica—Hungarian vetch 256 XXII,~455

V. sativa—Common vetch 257 XXIIl', 462

V, villosa—Hairy vetch 257 XXIII^ 465

Seed unit,—Seed.

Special treatment.—Place a blotter, piece of paper toweling, or filter

paper on the board to keep the seed from rolling. To examine the

hilum, chalaza, and other surface features the seeds can be placed in a

shallow dish of white sand to hold them upright. Insect infested

samples should be blown in a blower with a 3- to 4-inch tube to remove

the light, insect-infested seeds.

^ Special problems.—Seeds of some species are difficult to separate;

for example, F. villosa from F. dasycarpa and some seeds of F. sativa

from those of F. angustifolia. If indistinguishable seeds are present

affix a note on the record card and report somewhat as follows : "Certain seeds of Vicia sativa and F. angustifolia are indistinguishable."

If seeds of F. villosa have been attacked by insects the scar takes on

some of the same characters as those of the scar of F. dasycarpa. If

insect "stings" are noted, make an exhaustive study of the seed before

identifying it as F. dasycarpa.

Eeference is made below to pressing seeds with forceps, particularly

those "seeds" from which the contents, or a part of the contents, have

been eaten from within leaving the seed coats intact around the resultant cavities. The amount of pressure necessary to break through the

seed coats over these cavities is slight. It is somewhat comparable to

the amount of pressure needed to force a pair of sharp-pointed forceps

through a sheet of bond paper. Caution must be exercised when testing samples representing "unclean, farmer-run seed lots" to avoid

removing the immature seeds as inert matter. Do not remove seeds

which show evidence that insect eggs have been deposited in them but

which show no evidence thatthere has been further development of the

eggs.

Samples of hairy vetch frequently contain insect-infested seed with

openings in the seed coat. The analyst can usually determine by visual

examination whether the major or minor portion of the seed has been

destroyed. This may require careful study of individual seeds including "feeling" with pointed forceps to determine the extent of the

damage.

If the insect has made no opening in the seed coat the infested seeds

can usually be detected by their decayed and oily appearance and by

the dust particles which often cling to them. It is necessary to use

pressure to determine the relative extent of the destruction of each

seed. The infested seeds with the major portion destroyed will

crumble easily when rolled between the thumb and forefinger.

When broken at the points of infestation by pressing slightly with a

pair of sharp-pointed forceps the relative amount of damage can be

determined.
80 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

VALERIANACEAE (VALERIAN FAMILY)

VALERIANELLA

Kind of seed

Valerianella locusta var. oUtoria—Cornsalad.

The seed (fruit) is illustrated in plate XXXI, 652.

Seed unit,—A single seed or fruit.

Special treatment.—Blow to remove broken fruits without seeds.

Special prohlems.—Before beginning the purity analysis take a

few fruits from the bulk, break some apart and make sections of

others to see the position of the seed in the fruit and also to learn to

recognize the free or naked seed without the fruit. The fruit is three

parted but only one compartment or locule contains a seed. The

empty parts do not break apart easily but the one containing the seed

breaks off rather easily allowing the seed to fall free, or to cling to

the fruit structures.

Blowing does not separate all of the fragments containing seeds

from those which are free of seed but it reduces the number of fruits

which must be turned over to determine whether or not they contain

seeds. In classifying broken seed, those pieces having more than onehalf of their original size are classed as pure seed, whereas those

pieces representing one-half or less of the original size are classed as

inert matter.

UMBELLIFERAE (CARROT FAMILY)

APIÜM, DAUCUS. PASTINACA, PETROSELINUM

Illustration,

Kind ofseed Plate

Apium graveolens var. dulce—Celery

A. graveolens var. rappaceum—Celeriac

Daucus carota—Carrot XXVI, 535

Pastinaca sativa—Parsnip

Petroselinum crispum (P. hortense)—Parsley XXVI, 537

Seed unit.—Seed or fruit, fruit being a mericarp or half-fruit (referred to below as a seed).

Special treatment.—Blow or sift the samples to remove dirt and foreign seeds.

Special problems,—Seeds which adhere to one another must be separated in the purity analysis. Whole unbroken seeds are considered

pure seed and no attempt is made to determine whether an embryo

(true seed) is present. Broken seeds are classified by the one-half seed

rule. Seeds of celery and celeriac are indistinguishable.

SOLANACEAE (NIGHTSHADE FAMILY)

CAPSICUM, LYCOPERSICON, PHYSALIS, SOLANUM

Kind of seed

Capsicum spp.—Pepper.

Lycopersicon esculentum—Tomato.

Physalis pubescens—Husk tomato.

Solanum melongena var, esculentum—Eggplant.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 81

Seed unit,—Seed.

Special treatment—Sift samples to remove the fine dirt and blow

to remove fragments of fruits and seeds.

Special problems,—Seeds often cling together and must be separated

in the purity analysis. If broken seeds are present they must be

judged by the one-half seed rule. Shriveled, immature seeds are

classed as pure seed.

POLYGONACEAE (BUCKWHEAT FAMILY)

FAGOPYRUM, RHEUM, RUMEX

Kind of seed

Fagopyrvrm esculentum—Buckwheat.

Rheum rhaponticum—Rhubarb.

Rumex c^ceiosö^—Sorrel—Seed ülustrated in plate XIII, 235.

Seed unit.—Fruit, rarely a naked seed.

Special treatment,—Seeds of rhubarb have wings which may present a problem when dividing them mechanically. If the sample

cannot be divided mechanically, pour the seed onto a flat surface and

successively cut it in half until the sample is approximately the correct

size.

Special problems,—In processing the seed the outer husks (fruit

coats) may be broken off of some seeds. As an aid in identifying

these naked seeds they should be compared with known seeds of the

same kind from which the husks have been removed.

Samples of Buckwheat sometimes contain seeds of tartarian buckwheat, Fagopyrum tataricum. These two species can be distinguished

but because of their similarity may be overlooked unless the analyst

suspects their presence.

MALVACEAE (MALLOW FAMILY)

GOSSYPIUM, HIBISCUS

Kind of seed

Qossypium spp.—Cotton.

Hibiscus esculentus—Okra.

Seed unit,—Seed.

Special treatm^ent,—Cottonseed with lint on it can be passed through

a large mechanical divider with difficulty. When this is not feasible

pour the bulk sample onto a flat surface and divide it repeatedly until

the approximate amount required for the test is obtained.

Special problems,—Cottonseed with some of the lint on it should

be carefully examined for weed seeds which cling to the lint. There

is little difficulty in testing delinted samples.

LINACEAE (FLAX FAMILY)

LINUM

Kind of seed

Linum usitatissiwum—Flax.

See plate XXIII, 476, for illustration.

Seed unit,—Seed.

Special treatment,—Siît the samples to remove dirt and small fragments of broken seeds.
82 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

Special problems,—Samples often have broken seeds which must be

judged individually on the basis of the original size. If in doubt, the

questionable seeds should be lined up with unbroken seeds of a similar

size and shape. Fragments more than one-half the original size are

considered pure seed and pieces one-half or less than one-half the

original size are considered inert matter.

LILIACEAE (LILY FAMILY)

ALLIUM, ASPARAGUS

Kind of seed

Alliimi cepa—Onion.

A. porrum—^Leek.

Asparagus ofßcinalis—^Asparagus.

Seed wait,—Seeds.

Special treatment,—Sift the samples if fine dirt is present.

Special problems,—Many samples of each of the species contain

seeds which have not attained the dark color typical of these kinds.

These off-color seeds have the other characters of their kinds and should

be included with the pure seed. Seeds of onion and leek are somewhat

similar but can be distinguished from each other. The faces of the

seed of leek have small pitlike depressions while those of onion do not.

GERANIACEAE (GERANIUM FAMILY)

ERODIUM

Kind of seed

Erodium cioutarium—Alfilaria.

Seed iUustrated in plate XXIII, 469.

Seed unit,—^Fruit or seed.

Special treatment,—^The awn of the seed is spirally twisted making

it difficult to sample. The only satisfactory method is to pour the

sample on a flat surface and to halve it successively until the sample

is approximately the correct size.

Special problerm.—The seed units (fruits) are considered to be pure

seed if they are unbroken. If they are broken, they must be judged

individually and classified in accordance with the rule relating to onehalf of a seed.

CUCURBITACEAE (CUCURBIT FAMILY)

CITRULLUS, CUCUMIS, CUCÚRBITA

Kind of seed

Citrullus vulgaris—Citron and Watermelon.

GuGumis sativus—Cucumber.

C. melo—^Muskmelon or Cantaloup.

CucurUta pepo—^Pumpkin.

C. maxima and C. mosoJiata—Squash.

Seed unit.—Seed.

Special treatment,—Sift the samples to remove chaff.

Special ^rö&Zßm^.—Unbroken seeds, even though they are thin,

empty, or shriveled, are considered pure seed. If the seed is broken,

the contents are determined on the basis of the i/^-seed rule.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 83

CRUCIFERAE (MUSTARD FAMILY)

BRASSICA, LEPIDIUM, RAPHANUS, RORIPPA

ÍTJÍ iration, species, pjj^^g'

Kind of seed ^«^«

Brassica campestris—Bird rape 235 XVI, 315

B. campestris vars.—Turnip rape 235

B. chinensis—Pakchoi 235

B. hirta—White mustard 234

B. júncea—Cult. India mustard 235 XVII, 316

B. napus var. annua—Annual rape 234 -----: - - - -

B. napus va.r. hiennis—Winter rape 234 ÄV11, dl»

B. napus var. napobrassica—Rutabaga— 234

ß. nigra—Black mustard 235 XVll, 319

B. pekinensis—Pe-tsai 235

B. perviridis—Spinach mustard 235

B. rapa—Turnip 235

B. spp.—Vegetable mustard

B, olerácea var. acephala—Collards and Kale

B. olerácea var. hotrytis—Broccoli and Cauliflower

ß. olerácea var. capitata—Cabbage _ --

B. olerácea var. gemmifera—Brussels sprouts —_

B. olerácea var. gongylodes—Kohlrabi

Lepidium sativum—Garden cress -r-------

Raphanus sativus—Radish XVII, 337

Rorippa nasturtium-aquaticum—Water cress

Seed unit.—Seed.

Special treatment.—Sift to remove dirt or species or varieties of

different sizes.

Special prohlems.—Seeds of all crop plants of the Cruciferae with

the seed coats entirely removed are considered inert matter. The

principal problem in this family is identification of the seed. The

seeds of many of the kinds and varieties of Brassica can be identified,

especially by those who have made detailed studies of the group.

However, the specialist, at times, has to resort to growing tests to

make positive determinations of some seed lots. All samples of Brassica should be checked to see that they are correctly named. In doing

this it is good practice to attempt to* name the kind or variety before

observing the name under w^hich the sample was submitted. After

the sample has been tentatively named it must be checked with the

name under which it was submitted.

After a period of practice the analyst will find that he can correctly

name many kinds in the bulk by observation with the naked eye and

hand lens. Individual seeds of many kinds can be accurately and

positively identified only by growing tests. Keys, descriptions, and

illustrations are valuable aids in identifying seeds of Brassica but

skill in their identification can be developed only through comparisons

with actual samples and growing tests.

Seeds of wild mustard or charlock (Brassica haber) .^ a weed, are

occasionally found in samples of other Brassica species. Seeds of

the former can be distinguished by their round shape, smooth and

oily appearance. A stereoscopic microscope is necessary in identifying seeds of Brassica.
84 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

COMPOSITAE (COMPOSITE FAMILY)

CICHORIUM, CYNARA, HELIANTHUS, LACTUCA, TARAXACUM, TRAGOPOGÓN

Illustration,

Kind of seed Plate

Cichorium endivia—Endive

C. intyhus—Chicory XXXII, 690

Cynara cardunculus—Cardoon

C, scolymus—Artichoke

Helianthus annuus—Sunflower XXXIIl, 702

Lactuca sativa—Lettuce

Taraxacum officinale—Dandelion XXXIV, 730

Tragopogón porrifolius—Salsify . Seed unit,—Fruit; rarely a true seed.

/Special treatment,—Blow badly broken samples to remove fragments of the husks.

Special problems,—Seeds which adhere to one another must be separated in the purity analysis. Whole unbroken seeds are considered

pure seed regardless of whether they contain embryos (true seeds).

Broken seeds which can be seen to contain half or less than half an

embryo are considered inert matter. Naked seeds or embryos which

can be identified as the kind of seed being tested are classified as pure

seed. Seeds of chicory and endive cannot be positively distinguished

from each other. Seeds of chicory are generally darker colored than

those of endive but the color varies in different seed lots.

CHENOPODIACEAE, CANNABINACEAE, AND AIZOACEAE (GOOSEFOOT,

HEMP, AND CARPETWEED FAMILIES)

BETA, SPINACIA, CANNABIS, AND TETRAGONIA

Kind of seed

Beta vulgaris and varieties—Beet, Mangel, Swiss chard, Sugar beet.

Spinacia olerácea—Spinach.

Cannahis sativa—^Hemp.

Tetragonia expansa—New Zealand spinach.

Hemp seed is illustrated in plate XIII, 225.

Seed unit,—Fruit, specifically an achene in spinach and hemp ; fruit

-with enclosing calyx and one to many seeds in New Zealand spinach;

seed ball consisting of fused flower parts and one to many seeds in

Beta,

Special treatment.—Sift samples to remove the dust and particles

from broken fruits.

Special problems,—The unbroken fruits of spinach and hemp are

classed as pure seed regardless of whether they contain true seeds or

embryos. Broken seeds (fruits) are classified in accordance with the

i^-s^^d rule. Clusters of seeds should be separated and each examined

and classified on its own merits.

In testing spinach be on the alert for Fumaria sp. which is similar

in. appearance. Carefully note both the point of attachment and the

opposite end of the seed and compare these characters with the same

points on known seeds of both kinds.

All unbroken seed balls of Beta vulgaris are regarded as pure seed.

Broken seed balls in which all the seed cavities are exposed and which

appear to be devoid of seed are classed as inert matter. They are
TESTING AGRICULTURAL AND VEGETABLE SEEDS 85

not infrequent in lots of "sheared" seed. The naked seeds are judged

by the i^-seed rule. Seedsmen and growers sometimes request that

certain specified sieves be used for sugar beet seed.

The seed (fruit) of New Zealand spinach is hard and bony and

usually contains several seeds arranged in a ring around its top,

These structures are classed as pure seed except when the top portion

containing the true seeds is missing in which case they are classified

as inert matter.
PROCEDURES FOR DETERMINING GERMINATION

DEFINITION AND OBJECT

In seed-laboratory practice, germination is defined as the emergence

and development from the seed embryo of those essential structures

which for the kind of seed in question are indicative of the ability to

produce a normal plant under favorable conditions. Germination

is expressed as the percentage of the pure seed of the kind under

consideration which produces normal seedlings.

The environmental conditions for laboratory germination must not

only be specific enough to initiate growth in the seeds, but also must

be favorable for development of the resultant seedlings to a stage

whereby interpretation into normal and abnormal types may be made.

Definite methods for laboratory germination of the more common

agricultural and vegetable seeds have been set up in the rules for

seed testing. As knowledge of the germination behavior of seeds increases, certain changes will undoubtedly take place in these methods.

Although it is important that analysts keep abreast of new developments in research, it is more important that they follow the methods

set forth in the rules if any degree of uniformity in test results is

to be expected.

THE KINDS AND USE OF SUBSTRATA

GENERAL CONSIDERATIONS

The kinds of substrata listed in the rules for testing seeds are:

Germination blotters; paper toweling ; soil ; sand ; filter paper ; cotton ;

and creped cellulose paper wadding. Other substrata used in some

laboratories but not at present listed in the rules include sawdust,

peat moss, and mica. The substrata should (1) be nontoxic to the

germinating seedlings, (2) be relatively free of molds, other microorganisms, and their spores, and (3) provide adequate aeration and

moisture for the germinating seeds. From the standpoint of uniformity in testing, standard detailed specifications for the different

kinds of substrata would be most desirable. At present the Committee on Standardized Tests^ is working on this problem; except

for blotters, only general specifications have been developed. Whenever an analyst wishes to check any substratum for toxicity to germinating seedlings, timothy may be used as its roots will not develop

normally in the presence of toxic materials. In making such a test

some seed from the same seed sample should also be planted on similar

substrata known to be nontoxic, such as a high-quality filter paper.

The exact methods in the preparation of the substrata and the

placement of seeds thereon will vary in the different laboratories, de-

^ Membership of the Committee on Standardized Tests, Association of OflScial

Seed Analysts, consists of representatives of the United States Department of

Agriculture, Canadian Department of Agriculture, Association of Official Seed

Analysts, and the Society of Commercial Seed Technologists.

86
TESTING AGRICULTURAL AND VEGETABLE SEEDS 87

pending on the kinds of equipment, size of trays, vacuum counter

heads, and other variable factors. Certain techniques and procedures,

however, are more or less standard and are discussed herein to aid

analysts in interpreting the rules and footnotes applicable thereto.

BLOTTERS

The Committee on Standardized Tests has proposed the following

specifications for germination blotters :

Seed germination blotters: Weight 275 pounds per 500 sheets, 25 x 40 inches;

100 percent chemical wood ; ash content not to exceed 1 percent ; bursting strength

to be not less than 100 points ; pH to be between 6.5 and 7.5 ; water absorption as

measured in accordance with U. S. Federal Specifications UÜ-T-591 to be not

less than 5; Sulfides and other toxic chemicals not to exceed 0.0002 percent;

tensile strength (Kg. per 15 mm. width) : Machine direction—at least 40, cross

direction—at least 10. Blotters must be open and porous, insoluble in water

and slate gray or slightly lighter in color. Specifically, the color should approximate that found in the bluish Purple-Blue chart of the Munsell color scheme,

designated as: 2.5 PB 4/2 (i. e. bluish Purple-Blue, Value 4, Chroma 2). If the

fibers run mostly in one direction they should be in the short direction. Commercial tolerances may be applied to these specifications.

In the rules the capital letter B indicates "between blotters" which

is interpreted to mean a single blotter folded over so the seeds may be

placed between the upper and lower folds. It is desirable that blotters be cut to such a size that an appropriate number may be placed

on a germination tray with the least loss of space. The standard

germinator tray in use in many laboratories is 18% by 191^ inches

which will accommodate 24 blotters, cut 9% by 6 inches if folded and

placed 2 deep. In no case should the folded blotters be placed more

than 2 deep on a tray, and their position should be alternated at the

time of each preliminary count.

The symbol TB in the rules indicates "on top of blotter." If drying

of the blotters is excessive, two thicknesses of blotters will provide

moisture over a longer period of time than a single layer. If the

moisture in the germination chambers is adequate, a single blotter

under the seeds may suffice.

"Eaised blotters" are listed as an alternate method for some kinds

of seeds for which top-of-blotter tests are indicated. The seeds are

placed between folded blotters on which the edges of the bottom fold

have been turned up about one-quarter inch so as to provide a support

for the top or cover, thus avoiding contact of the cover with the

seed. This method is of particular value for use in germination

chambers where excessive drying of seeds or seedlings on top of

blotters may occur.

When blotters are used in Petri dishes, they are cut to size and two

thicknesses placed in each dish. Certain seeds when placed between

blotters or on top of blotters may roll easily. When placing such

seeds in test, it is desirable to turn up the outside edges of the blotters

slightly to avoid this danger. The moisture content of the blotters

should be observed daily and water added with a sprinkling bulb as

necessary. Care should be taken not to saturate the tests at any time

or to let them dry out. There will be less spread of mold on tests

held at the higher temperatures if they are kept slightly on the dry

side. Aft^r the initial intake of water less moisture will be required.

The position of the top and bottom blotters should be reversed at

the time of each preliminary count when they are stacked two deep.
88 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

PAPER TOWELING

The Committee on Standardized Tests has not developed specifications for toweling. The National Bureau of Standards has tested

several samples of towels for the Grain Branch, Production and

Marketing Administration. On the basis of these tests it would appear that toweling meeting the following proposed specifications

would be acceptable as a germination substratum :

Paper toweling: Towels shaU be 11 inches wide and cut or perforated in 14-

inch lengths; bursting strength shall be 25 to 30 points, tensile strength shall

not be less than 2 kg. per 15 mm, width strip. The absorptivity shall be such

that when a strip of the paper %-inch wide is suspended vertically with the

lower end immersed in water to a depth of 1 inch, water shall rise in the strip

to a height of not less than l^^ inches within 5 minutes ; fiber composition to be

100 percent chemical wood ; ash content shall be not more than 0.7 percent ; the

jpH shall be not less than 6.0 and not more than 7.5 ; sulfide content not to

exceed 0.0002 percent ; towels shall be relatively free from any other chemicals

injurious to germinating seeds ; must be water insoluble, color to be brown.

In the rules the symbols applicable to toweling are as follows :

T=between folded paper toweling.

R== rolled towels.

It is usually desirable to have paper cut to such a size that it can

be used for both the folded and rolled towel tests. The Federal laboratory has found that a size 11 by 14 inches so folded or placed that

three thicknesses will be both under and over the seeds is very satisfactory. In no case should folded towels be stacked more than two

deep on a tray. EoUed towel tests may be placed in either a horizontal or vertical position on the trays, the latter being preferred in

most laboratories. Various types of metal racks in which the rolls

may be placed in an upright position are in use.

Upright rolls should not be crowded on the trays because of the

possible spread of molds and because excessive heating may occur

toward the center of a large mass of closely spaced rolls. The towels

should be rolled loosely enough to allow normal expansion of seeds

and seedlings during the test period. The large-seeded kinds such as

beans should be observed closely as they often double in size upon

absorption of water. Tightly rolled towels may (1) cause abnormal

swelling of the hypocotyls or roots on seedlings the size of beans and

peas, (2) encourage the spread of fungi, and (3) make unrolling

difficult because seedlings frequently break through the rolls and

grow into adjacent tests.

Attention must not only be given to the initial rolling but also to

the rerolling at the time of the preliminary counts. Even though it

is not possible or feasible to make a preliminary count it is recommended that all rolled towel tests be unrolled and the seeds examined on the day designated in the rules for the preliminary count.

Jf the tests are too wet, the upper layer of towels may be wrung out

and again placed over the seeds, or a single dry sheet may be inserted

over the upper towels before they are rerolled, to absorb some of the

excess moisture. It has been found that sometimes very hard seeded

legumes or seed of low viability will not use the expected amounts

of water, necessitating the above procedure. The position of the

bottom row of seedlings may need to be adjusted at this time to give

the hypocotyls and roots an opportunity to develop normally. This
TESTING AGRICULTURAL AND VEGETABLE SEEDS 89

is particularly true if the bottoms of the towels have been turned up

to guard against seeds falling out during the course of the test.

Flat, folded towels may be stacked two deep on the trays, but the

position of the upper and lower towels should be shifted at the time

of the preliminary counts. To guard against losing seeds, especially

round ones, during the germination test, the edges of the towels should

be folded up for about % inch. They should not be as wet as upright

rolled towels at the time the tests are set up, since water may be

retained in the folds with subsequent "flooding" or lack of aeration.

Itis recommended that when folded towels are used they be immersed

in water until saturated, allowed to drain a few minutes, and then

some of the excess water pressed out before the seeds are placed in

test.

Since an even supply of moisture should be maintained during the

progress of the test, daily observations should be made and tests

rewatered as necessary. Care should be taken not to saturate the

tests at any time or to let them dry out. A rubber sprinkling bulb

will be an aid in rewatering.

SAND AND SOIL

Specifications,—Detailed specifications for kinds of sand and soil

have not been approved by the Committee on Standardized Tests.

A clean, sharp quartz or builder's sand, not too fine, is preferred over

soil by some analysts. A sandy loam soil with a moderately high

water-holding capacity is a suitable soil type. If the available soil

is too heavy (contains considerable clay), it can be mixed with sand

to obtain a more friable, easily handled substratum. Based on tests

made by the National Bureau of Standards in which sand used in

different seed-testing laboratories was tested, the following proposed

specifications appear to be appropriate :

Quartz sand.—^Approximately pure quartz which shall yield upon analysis not

less than 99.5 percent SÍO2, practically free from dust and fine particles ; particle

size to vary from approximately 0.05 to 0.8 mm.

Builder's sand.—^Washed and relatively free of organic material, 98 to 100

percent quartz yielding not less than 99 percent SÍO2, particle size to fall between

0.05 and 0.8 mm. in diameter.

Sterilisation,—Most garden soils, and sometimes sand, contain

organisms that may cause damping-off of seedlings. Also, weed

seeds are frequently present, the emergence of which in a laboratory

test would be undesirable. To avoid the damping-off of seedlings

and the growth of weed seeds, sterilization is recommended for all soil

and sand used in laboratories. Owing to the breakdown of organic

materials and possible formation of toxic compounds, soil should be

exposed to the air from a day to a week subsequent to sterilization

before using. The time required depends on the organic content of

the soil, the efficiency of aeration and possibly other factors.

Moisture content.—The amount of water to be added to sand for

germination tests is specified in the rules for seed testing. When

sarid alone is used it is very importantto measure the water accurately

because it is impossible to approximate the moisture content by "feeP'

alone. The following formula is to be used as a basic guide in the

preparation of sand, either the quartz or builder's type :

118.29 cc. (1 gill) sand The number of cc. of water to add to

Its weight in grams ^ each 100 grams sand.
90 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

The amount of water provided by this formula may have to be

modified slightly, depending on the kind of seed being tested. For

example, slightly more moisture should be added when the larger

seeds are to be tested. Only general directions are given in the rules

for adding moisture to soil. Water should be added until the consistency of the soil is such that a ball is formed by squeezing in the

palm of the hand but will break freely when pressed between two

fingers or dropped.

Preparation and care of the test.—Paraffined cardboard boxes which

come in two sizes, 8i^ by 8i^ by 1% and 4:l^ by 4% by li/^ inches,

are generally used as containers for sand and soil tests. Four of the

former and 16 of the latter fit on the standard germination tray used

in many laboratories. The first step in the preparation of sand or

soil is to sieve it in order to remove any large particles or foreign

bodies. A sieve made of hardware cloth (8 mesh per inch) has been

found very satisfactory for this purpose. After the sand or soil has

been sieved the water should be added gradually according to the

directions outlined above. The dampened mixture should then be

again passed through a coarser mesh sieve (about 4 mesh per inch)

than that used for the dry materials. This second sieving insures a

more even moistening and aeration of the substratum.

At least one-half inch of sand or soil should be placed in the bottom

of the containers to be used for the laboratory test, and should be carefully leveled off. The seeds may be placed by hand or with a mechanical counting plate, care being taken to gently force the seeds part way

into the substrata so that they will remain in place while being covered.

The depth of the covering will vary somewhat with the size of the seed

being tested, ranging from approximately one-fourth of an inch for

clovers to one-half to three-fourths of an inch for corn and beans. The

placement of damp blotters over the sand or soil boxes until the seedtings emerge will help in the maintenance of the initial moisture supply

of the substrata. Care must be exercised not to overwater the sand or

soil for the duration of the test.

FILTER PAPER

Filter paper is to be used as the substratum for the fluorescence test

of ryegrass. The specifications in use in the Federal laboratory for

filter paper are as follows :

Filter paper,—The paper shaU be white, cut in sheets 9 x 9i^ inches. Bursting

strength shall be not less than 12 points. The absorptivity shall be such that

when a strip of paper %-inch wide is suspended vertically with the lower end

immersed in water to a depth of 1 inch, water shall rise in the strip to a height of

not less than 2^2 inches within 5 minutes ; fiber composition—100 percent rag ;

ash content shall be not more than 0.2 percent. The pH shall be not less than 6.5

Ijercent and not more than 7.5 percent. Paper shall be free, exclusive of tolerances, from any chemicals injurious to germinating seeds; must be water

insoluble.

When filter paper is used as a substratum in Petri-dish tests, Whatman's No. 2 or its equivalent is specified in the rules.

COTTON

A layer of nontoxic, sterile, absorbent cotton may be used as the substratum in Petri-dish tests. Pieces approximately the size of the dishes

can be cut from the rolls and then pulled into a round shape to fit. It
TESTING AGRICULTURAL AND VEGETABLE SEEDS 91

may be desirable to add a measured amount of water to each dish, since

it is rather difficult to ju^ge the moisture content without feeling each

piece of cotton after th§ water is added. If the latter procedure is

followed, any excess wat^r may be squeezed out and the cotton replaced

in the dish. One objection to the use of cotton is that the roots of the

seedlings will grow into it making removal of the sprouts for observation difficult. Itis possible that it may be used more widely if a single

disk of blotter or filter pamper is placed over the cotton, thus providing a

more resistant surface to root penetration. The blotter Avould also

form a dark background^ contrasting in color to that of the seedling.

CREPEp CELLULOSE PAPER WADDING

A material commonly known under the trade name "Kimpak" may

be used as a substratum for broadbean, lima bean, velvetbean, and Beta

vulgaris. The rules define creped cellulose paper wadding as 0.3-inch

Kimpak or its equivalent. In using this substratum a piece approximately 9 inches square is covered with a single thickness of blotter

through which holes are punched for the seeds. The seeds of lima

bean, broadbean, and vejlvetbean are pressed for about one-half their

thickness into the creped paper wadding.

Since creped cellulose wadding will fall apart when wet it is necessary to place a sheet of ^axed paper under it and then add the water

carefully, preferably sqmirting it on with the aid of a hand sprinkler.

To each square of creped wadding, add 250 cc. of water for beans and

85 cc. of water for beets^ Saturate a 9- by 9%-inch blotter, allow to

drain, fold over all four edges for approximately one-fourth inch to

elevate them slightly, punch a slit in the blotter at each position a seed

is to be placed and then put the blotter on the Kimpak with folded

edges down. The beansshould be carefully inserted into the slits, care

being taken to evenly space them and to push them in far enough to

make contact with the nioist Kimpak and yet to be held upright by the

blotter. After the see4s are in place, one or two tissues of the dry

cellulose wadding should be peeled oif and placed over them to keep

the seed coats moist. The covering should be lightly sprinkled with

water before being placpd in the germinator.

Because of its high f^ater-holding capacity, extreme care must be

taken in using this type bf substratum to always measure the water and

to use a covering blottef-. The blotter as used with beans serves as a

support for the germinating seeds, keeps them from touching each

other, and allows mor| aeration than if the seeds were embedded

in the Kimpak. For b^ets, it merely serves as a cover. It will not be

necessary to rewater thèse tests unless excessive drying occurs during

the course of germinatijon.

PEAT MOSS

Granulated peat mosp mixed with sand or soil is preferred by some

analysts as a substratui|i for tests requiring a long period of treatment

at a low temperature. It has a large water-holding capacity, is light

and spongy, and its acid nature tends to discourage the growth of mold.

A mixture of peat mosslwith soil and sand makes a good substratum for

germinating New Zealand spinach seed. Peat moss is not included in

the rules for seed testing and its use is not recommended except in

mixtures containing so^l or sand.

957116—52 7
92 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

SAWDUST

Sawdust has been recommended as a substitute for soil and sand.

It has several good qualities but owing to the different oils and resins

contained in wood, it is necessary to check each lot carefully as the

sawdust may contain toxic materials injurious to germinating seedlings. This is one of the principal objections to the use of sawdust as a standard germination substratum. Sawdust has not been

standardized nor included in the rules as there is no known source of

an acceptable quality. As in the use of sand, it is absolutely necessary to measure the amount of water used. Sawdust should not be

used in laboratory testing until such time as it may be included in the

rules.

MICA

The use of expanded mica, known under such names as "Vermiculite"

and "Terralite,^' as a laboratory substratum has only been experimental. It is widely used in greenhouses as a covering for seeds when

grown in soil flats, and for such purposes as the propagation of cuttings. The advantages for laboratory use appear to be that it is (1)

relatively inexpensive, (2) sterile, (3) inert in nature, (4) light in

weight, (5) spongy and porous, and has a tremendous water-holding

capacity. Its disadvantages are twofold: (1) It is very "flaky" and

will stick to the hands of workers and to the surfaces of the tools used

in mixing and placing it for test ; and (2) it may hold too much water

for the proper development of normal seedlings of certain kinds.

For instance, "watery seedlings" have been reported on beans grown

in mica but when tested in other substrata the seedlings were normal.

This objection might be overcome by mixing measured amounts of dry

mica with sand or soil. In any event, although not now generally

used, it may have future possibilities when used alone or in combination with other materials as a substratum for laboratory tests.

PETRI-DISH TESTS

In the rules the capital letter P indicates "covered Petri-dish tests,"

which may contain as the germination substratum one of the following: (1) Two layers of blotters; (2) one layer of absorbent cotton;

(3) 5 layers of paper toweling ; (4) 5 layers of filter paper ; or (5) %-

inch layer of sand or soil. Except as provided for those kinds of seeds

requiring a substratum with high moisture, the substrata in the Petri

dishes should never be so wet that a film of water is formed around

the seeds. Rewatering must be done very carefully, preferably

squirted under the edges of the substrata with a medicine dropper.

PREPARING THE TEST

NUMBER OP SEEDS

The rules specify that at least 400 seeds shall be tested for germination except that in mixtures, 200 seeds of each of those kinds present

to the extent of 15 percent or less may be used in which case an additional 2 percent is to be added to the regular germination tolerances.

The seeds shall be tested in replicates of 100 seeds or less.

SOURCE OF SEEDS

Special care must be taken to select the 400-seed subsample exactly

in accordance with the requirements of the rules, which are as follows :
TESTING AGRICULTURAL AND VEGETABLE SEEDS 93

(a) When both purity and germination tests are required, seeds for germination shall be taken from the separation of the kind, variety, or type considered

pure seed and shall be counted without discrimination as to size or appearance. (Ô) When only a germination test is required and the pure seed is estimated

or determined to be at least 98 percent, the pure seed for the germination test

may be taken indiscriminately from a representative portion of the bulk.

(c) When only a germination test is required and the pure seed is found to

be less than 98 percent the pure seed shall be taken indiscriminately from a pure

seed separation made according to the provisions of these rules and regulations

which govern the separation of the kind, variety, or type considered pure seed

except that other crop seeds, inert matter, and weed seeds need not be separated.

When a purity analysis is not made and the sample is large, the

use of a mechanical divider is recommended for obtaining the germination subsample. Small bulks may be poured directly into a small

mixing pan and stirred by hand. Large seeds, such as beans, which

may be injured by dropping through a mechanical divider, may be

poured out on a flat surface and repeatedly subdivided with the aid

of a flat board or ruler into a small subsample.

COUNTING THE SEEDS

The counting of the 400 seeds without discrimination as to size or

appearance may be done by hand, by the aid of a counting board, or

with the aid of a vacuum seed counter. It should be emphasized that

only free-flowing, smooth seeds lend themselves readily to the vacuum

method and only large seeds can be successfully counted with counting boards. However, if a laboratory handles a volume of kinds,

such as cereals, vegetables, legumes, or certain of the grasses, that

can be successfully counted by the vacuum method, the rapidity of

placing the seeds in test and the even spacing of the seeds on the substratum will more than justify the use of a vacuum counter. Vacuum

counters are now regarded as standard seed-laboratory equipment.

The vacuum counter is designed to avoid personal bias in selecting

seed, but it may be misused to defeat this purpose. It is important

to spread the seed well over the face of the counter. If uneven seed,

such as alfalfa with some immature flat seed, is placed on one edge

and the counter tipped, the rounded seeds will move across the face

of the counter more rapidly and be held on the holes not in proportion

to their presence in the sample.

SPACING THE SEEDS

The proper spacing of seeds to reduce to a minimum the contact

of seedlings with eacK other during germination cannot be emphasized

too strongly. This is especially important for large-seeded kinds and

seed stocks infected with storage or other fungi. There have been

no regulations with respect to spacing of seeds included in the rules

but the Standardized Test Committee, in 1949, made the following

recommendation :

Careful attention should be given to the spacing of seeds in blotters, towels,

or sand. The distance between seeds should be not less than 11/2 to 5 times the

width or diameter of the seed, the basis of spacing being the size of the seed

to be tested.

Since certain seeds, such as beans and peas, m^ij double in size after

the absorption of water, and others, such as spinach and bluegrass,

do not become appreciably larger, proportionate allowances for their

expected increase in total area must be made when they are spaced

on the substratum.
94 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

PROVISION AND MAINTENANCE OF ENVIRONMENTAL CONDITIONS

MOISTURE AND AERATION

The analyst is cautioned in the rules for seed testing that the substratum must be moist enough at all times to supply the needed moisture to the seeds, and that there is always danger of supplying excessive moisture which may restrict aeration. Except as provided for

those kinds of seeds requiring very moist substrata, the blotters, towels,

or other substrata should never be so wet that a film of water is formed

around the seeds. For most kinds of seeds, blotters or other paper

substrata should not be so wet that, by pressing, a film of water forms

around the finger. The analyst should give particular attention to

the explanatory notes in the column headed "Eemarks" in the germination table of the rules, regarding the care of substrata for the kinds

of seed that require special attention with regard to maintenance of

proper moisture conditions during the test period.

The necessity of adding water to the siibstratum subsequent to

placing the seeds in test will depend on the evaporation from the substrata in the germination chambers. Since the rate of evaporation

will depend, among other factors, on the relative humidity of the

air, it is desirable to keep water in the germination chambers or to

provide other means of maintaining a high relative humidity. In

1949, the Standardized Test Committee recommended that the relative humidity around tests should be approximately 95 percent and

that great care should be taken to insure that the methods and equipment used will maintain approximately this level of moisture. All

tests should be examined daily to insure that the moisture content

of the substratum is near optimum. Such mechanical aids as small

rubber florist's bulbs and medicine droppers have been found to be

very useful in enabling the analyst to rewater tests without danger

of overwetting the substratum.

TEMPERATURE

Temperature is one of the most critical factors in the laboratory

germination of most of the seeds listed in the rules. It is not possible

to control temperature without special equipment designed for that

purpose. In 1949, the Association of Official Seed Analysts adopted

the provision that a permissible variation of only 1° C. be allowed

from the temperature specified in the rules for laboratory germination

of seeds. Daily observations and records should be made of the temperature inside each germinator to insure attention to this detail.

It cannot be emphasized too strongly that correct temperature controls must be maintained at all times.

When referring to the rules the worker should keep in mind that

a single numeral indicates a constant temperature and two numerals

separated by a dash indicate an alternation of temperatures in which

the test is held at the first temperature for approximately 16 hours

and at the second temperature for approximately 8 hours per day.

If temperatures cannot be conveniently alternated over week-ends

and on holidays, the seeds are to be held at the lower temperature

during such time, unless otherwise indicated under "Remarks." The

daily alternation of temperature is either brought about by manually

transferring the tests from one germination chamber to another or by
TESTING AGRICULTURAL AND VEGETABLE SEEDS 95

changing the temperature of the chamber in which the seeds are

placed. Some germinators are equipped with time clocks which

switch the electrical circuits at preestablished time intervals, causing

the alternations of temperature.

LIGHT

Light is required for the germination of most of the grasses and for

some vegetable seeds. Relatively little research has been done with

respect to the effects of specific wave lengths and intensities of light

required for the commonly tested agricultural and vegetable seeds.

There are some data to show that freshly harvested seed is more likely

to be benefited by light than older seed and that light may compensate

for certain unfavorable germination conditions. Fluorescent light has

been used successfully in lieu of natural daylight and is preferred in

testing because the wave lengths and intensity can be standardized,

within limits. Available evidence indicates that daylight fluorescent

light is as effective in stimulating germination as natural daylight.

There are two principal objections to using fluorescent lights placed

inside the germination chambers : (1) Fluorescent lamps produce considerable heat which must be counterbalanced by a cooling system;

and (2) they tend to cause drying of the substrata.

The Association of OiEcial Seed Analysts has accepted the recommendation that light should be evenly distributed over the tests, with

a range of intensity from 75 to 150 foot-candles. A variation of plus

or minus 25 foot-candles on the tests is not considered important at

optimum intensity. Seed technologists should check their equipment

and. if necessary make the necessary adjustments to comply with this

recommendation. Weak light will not provide the necessary stimulus

to cause some seeds to germinate while intense light retards and depresses the development of aerial organs of the seedling.

Tests should be subjected to light for only a part of the test period.

The usual procedure is to provide 8 hours of light during the day

period. While a somewhat shorter exposure period may be sufficient

there are not enough available data to justify a definite statement on

this point.

SANITARY CONDITIONS OF EQUIPMENT AND SUPPLIES

The germination substrata and supplies should be kept as clean as

possible in order to minimize the growth and spread of fungi and

bacteria on tests. Such supplies as blotters, towels, and cardboard

boxes for sand or soil tests, which will be discarded after a single use

should be stored in a dry place protected from dust. Permanent supplies, such as Petri dishes or aluminum containers for soil tests, should

be thoroughly washed with hot water and soap or other detergent

after each use and thoroughly rinsed and dried. It is not necessary

to wash metal germination trays after each use unless they appear to

have mycelia of molds clinging to them.

Germinators should be cleaned periodically by flushing with hot

water to which a detergent, or formaldehyde may be added. It is

not usually necessary to fumigate germinators but, if such a procedure is deemed essential, a solution of potassium permanganate and

formaldehyde has been used and recommended as follows : Place 25

grams of potassium permanganate in a quart can and add 50 cc. of
96 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

40-percent formaldehyde solution. The permanganate should be

shaken into a pile on one side of the can and the formaldehyde solution

gently poured into the bottom of the can. Place the can in the germinator, close the door immediately and leave it closed overnight.

Eemove the can the next day and thoroughly air out the germinator

before it is used for germination tests so that the toxic effects of the

fumes will not affect the seedlings.

INTERPRETATION OF THE GERMINATION TEST

DATES OF PRELIMINARY AND FINAL COUNTS

The rules specify the days on which the first counts and the final

counts are to be made for the different kinds of seeds. The date stated

for the first count is approximate and a deviation of 1 to 3 days is permitted. Counts made between the first and final counts are at the

option of the analyst and will frequently vary with different samples.

In general, soil or sand tests may be left for the final count only,

whereas tests on artificial substrata should be examined every 2 or 3

days, especially during the first 10 days of test. Grasses needing longer

than 10 days to completely germinate usually need counting only once

a week after the fourteenth day of test. A convenient schedule for

grasses having a test period of 21 or 28 days is to count on the tenth,

fourteenth, twenty-first, and twenty-eighth days.

When samples are prechilled, the length of time they are prechilled

is to be added to the usual test period unless otherwise specified in

the rules. For instance, a sample of Kentucky bluegrass seed that

requires prechilling must be held in test for a total of 33 days, which

is the sum of a 5-day prechill period and a 28-day regular test period.

Experience has shown that it is not always necessary to hold the

samples in test for the additional prechill period as the conditioning

of the seed during prechilling greatly accelerates the speed of germination when the tests are placed at the higher temperatures. Consequently, as more information is accumulated on the speed of germination subsequent to prechilling, it may be possible to reduce the total

germination test period from that now required by the rules.

GUIDES FOR CLASSIFICATION OF SEEDLINGS

Germination is defined in the rules under the Federal Seed Act as

follows :

A seed shaU be considered to have germinated when it has developed into a

normal seedling. Broken seedlings and weak, malformed, and obviously abnormal seedlings shall not be considered to have germinated.

This is in agreement with the definition of germination in the first

paragraph on page 86.

The rules of the Association of Official Seed Analysts and the rules

promulgated under the Federal Seed Act provide that the photographs of normal and abnormal seedlings prepared by the Federal

laboratory and approved by the Association shall be used as standard

guides for classification of seedlings. The negative numbers of the

photographs are listed in the rules in the column under the heading

"Remarks" following the respective kinds of seedlings to which they

apply. In addition, the Association rules provide that soil or sand

tests are to be used as a standard guide for the evaluation of germina-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 97

tion tests made on approved artificial media in determining the classification of questionable seedlings. This technique is intended to provide a method of checking the reliability of tests made on artificial

substrata when there may be doubt as to the proper evaluation of such

tests. It does not mean that all samples are to be tested in sand or

soil. Means of distinguishing between normal and abnormal seedlings are set forth for specific groups under the heading "Application

of Germination Procedures to Specific Groups."

The analyst should keep in mind that normal seedlings should have

a well-balanced symmetrical growth pattern of all their essential parts

and that when one part shows stunting or weakness in respect to the

growth of another part, some abnormality should be suspected. In

conducting the germination test it is very important that all seedlings

be allowed to develop to a stage at which it can be determined whether

the essential plant parts are present. The interpretations of normal

and abnormal seedlings in this manual are those followed in the Federal seed laboratories and are based primarily on the photographs

of seedlings approved as standard guides for germination by the Association of Official Seed Analysts.

CAUSES OF ABNORMAL SEEDLINGS

Declining vitality.—Seeds which are aged, or have been subjected

to unfavorable storage conditions are usually slow to germinate.

Some of the essential plant parts are frequently stunted or lacking and

saprophytic fungi may interfere with the growth of the seedlings.

In regard to samples that are slow in sprouting but which produce

normal seedlings the Standardized Test Committee recommends that

a notation should be made on the report as follows: "This sample

shows evidence of declining vitality."

Infection with pathogenic organisms.—Although seed infected

with certain pathogenic organisms may initiate growth, one or more

of the essential seedling structures frequently may become damaged

or destroyed by the fungi or bacteria. Since the manifestations of

disease on the seedlings are largely dependent on the environmental

conditions during the test period, results may be erratic unless the

germination conditions are carefully controlled. The following

kinds of seeds are usually troublesome in this respect: Velvetbean;

broadbean; lima beans ; soybeans ; peanuts; crotalaria; cowpeas;

garden peas; chickpeas; sweetclover; alfalfa; cotton; oats; corn;

sorghum; wheat; barley; rye; rhubarb; beets; celery; radish; and

flax. Should a seedling decay as a result of infection from an adjacent seed it should be regarded as normal.

Mechanical injury.—Mechanical breakage of seeds may occur during the harvesting, threshing, handling and processing operations such

as scarification, and the milling processes designed to remove certain

accessory seed structures. Injuries of this type are found principally

on the following kinds : Beans ; peas ; cowpeas ; lupines ; peanuts ; soybeans; vetches; clovers; alfalfa; black medic; trefoil; crotalaria;

sericea lespedeza; rye; flax; onion; cardoon; sunflower; beets (by

the shearing process) ; timothy; reed canary grass; tall oatgrass; and

certain of the native range grasses. Mechanical injury to grass seeds

usually occurs during combining or the special milling processes designed to remove certain accessory seed structures.
98 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Considerable research on mechanical injury to beans of the field,

garden, and lima types has proved thatthe breakage occurs principally

during the threshing process. Thresher injury has been suspected as

the cause of breakage in samples of crimson clover. In some cases

it has also been attributed as the cause of injury to hairy vetch, peas,

blue lupine, and clover seeds. The mechanical scarification employed

to reduce the hard seed content in certain legume seeds is a frequent

cause of breakage.

Mechanical injury to seeds may interfere with normal seedling development or it may completely prevent development, depending on

the extent and place on the embryonic plant where injury occurs.

Insect injury,—Seeds that have been infested with insects may produce seedlings which lack some essential part or structure, or the seedlings may be severely stunted or weakened. The principal problems

which analysts will encounter are : Weevil damage to field peas and

cowpeas ; Bruchus damage to vetch ; chalcid fly damage to alfalfa and

red clover; and damage to certain of the cereals, such as corn, rice,

sorghum, and rye, which have been in storage for a long period of

time. A condition known as "honey-dew" has been found on alsike

clover seed. It is an aphid secretion which forms a sticky mass on

the outside of the seeds causing them to cling together in clumps.

Although it detracts from the appearance of the seed, it has not been

reported as harmful to germination.

Chemical treatment of seeds,—Seeds which have been overtreated

with toxic fungicides, such as the organic mercurial compounds, have

been known to produce abnormal seedlings. The symptoms include

stunting of the growth in length of roots and thickening of the roots

and hypocotyls on artificial substrata. Development may or may not

be normal in soil, apparently depending on the dosage, types of soil,

and possibly other factors. In some cases observed, the treatment

had been so severe as to permanently kill certain of the essential seedling organs.

Seeds that have been treated or accidentally subjected to certain of

the new chemical insecticides and herbicides such as DDT and 2-4-D

may yield abnormal seedlings. Exposure to the fumes of the latter

may produce abnormalities. Check tests in soil or sand will be necessary for proper evaluation of seedlings exhibiting any great amount

of treatment injury when grown on artificial substrata. Unless the

seedling organs have been destroyed by the treatment, a greater number of normal seedlings may develop in soil than on an artificial substratum where the toxic substances may come in direct contact with

the germinating seedling.

Metal germination trays,—Seed germinated on paper substrata

placed directly on metal germinator trays may produce seedlings with

shortened, thickened, or discolored radicles. Such abnormalities are

apparently caused by soluble zinc compounds dissolved from galvanized trays, galvanized trays given a thin copper finish, or from copper trays coated with acid during the soldering process. Injury to

the roots of common vetch seedlings grown directly on old copper

trays has been observed in the Federal laboratory. A sheet of waxed

paper placed under the towel substrata has been found to protect the

seedlings from such injury. Galvanized trays may be protected with

lead-free paints but the paint must be replaced from time to time as

it wears off.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 99

Toxicity of substrata,—Seedlings grown on or in artificial substrata

containing certain toxic materials, such as sulfuric acid or toxic pigments, may exhibit root inhibition or injury. Injury to the roots of

timothy seedlings grown on blue blotting paper has been reported,

and similar effects from growing seedlings on white paper toweling

treated with sulfuric acid have been observed.

Chemicals in tap vyater.—Seeds germinated in tap water containing

injurious chemicals may fail to germinate or produce abnormal seedlings. Retarded germination of Hypericunh seed due to calcium in

the tap water has been reported. It has been suggested that chlorine

in tap water may be harmful, but this is not supported by published

data. Tap water is used in most laboratories rather than distilled

water except when solutions of potassium nitrate are prepared. The

analyst should be on the alert for any possible contamination of the

tap water. If in doubt, the water can be checked against a control

test set up with distilled water.

Frost da/inage,—Seedlings grown from frost-damaged seeds are especially difficult to evaluate. Growth is initiated in most of the frostdamaged seed but the resultant seedlings are too weak to produce

normal plants. Sand or soil tests are very highly desirable, especially

on frost-damaged cereals.

Mineral, deficiency,—It has been found that deficiencies of certain

minerals in the soil on which seeds are produced will cause specific

types of abnormal development of the cotyledons or plumules in some

varieties of peas and beans. Manganese deficiency is characterized

by the appearance of sunken, brown, and slightly pithy areas in the

center of the ñat surfaces of the cotyledons, and sometimes with browning of the plumule in beans. Peas appear to be particularly susceptible to this type of injury which has also been reported as occurring

on bfoadbean and runner bean.

Boron deficiency has been reported for peas and is characterized

by injury to the plumule which may be stunted, multiple branched,

or undeveloped. The seed analyst can determine whether the injury

is owing to lack of boron by germinating the sample with and without

added boron. Leggatt {3\) found that a 0.01-percent borax solution

may be used to moisten the germination medium or the seed may be

dusted with pure borax or in one-tenth dilution with talc.

FUNGI INTERFERING WITH THE GERMINATION TEST

The control of saprophytic fungi developing on the seeds or substrata is a major problem to seed analysts, necessitating special care

in the spacing, watering, selection of substrata, and care of the seeds

while in test. The Committee on Standardized Tests made a recommendation in 1949 regarding this, as follows :

All ungerminatecl seeds which are decayed, mouldy, and obviously dead, should

be removed from samples in which saprophytic moulds are a problem at the time

the initial and subsequent counts are made.

Besides the saprophytic fungi and various bacteria which may develop and spread easily in germination tests, there are parasitic fungi

which are associated with certain kinds of seeds. The latter may

occur on fresh, strong^ samples with the infection often being clearcut and confined to individual seeds. Should a seedling become

decayed as a result of infection from an adjacent decayed seed, it
100 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

should be considered as normal. Laboratory practices which will

minimize the spread of molds include proper spacing of seeds, control

of temperature, removing decayed seeds, proper aeration, and keeping

the tests as dry as possible and yet providing adequate moisture for

germination. Questionable samples should be checked by testing in

soil or sand.

DISTINGUISHING BETWEEN DORMANT AND DEAD SEEDS

Frequently the analyst must resort to means of distinguishing

between dormant and dead seeds. All samples suspected of being

dormant must be subjected to the conditions for breaking dormancy

as set forth in the rules. Sometimes one can tell by the condition

of the seed, after it has been in test for a few days, whether it is dead

or dormant. Dead seeds often decay, become covered with fungi,

become soft, or the embryos become soft and discolored, whereas

dormant seeds are more apt to remain firm and relatively free of

mold. Sometimes when erratic sprouting occurs on samples with

dormant seeds, a retest put in under conditions calculated to be more

optimum for overcoming the dormancy will result in uniform germination. This has been observed especially on certain samples of

tomato seed. Samples with dead seeds are not likely to exhibit such

erratic sprouting.

DISTINGUISHING BETWEEN HARD SEED, SWOLLEN SEED, FIRM UNGERMINATED

SEED, DEAD SEED, AND GERMINATED SEED

In laboratory practice, hard seeds are defined as follows :

Seeds which remain hard at the end of the prescribed test because they have

not absorbed water, due to an impermeable seed coat, are to be counted as hard

seed.

The kinds of seeds recognized as often having hard seeds are indicated by a footnote in the table on germination in the rules. The

rules provide that if at the end of the germination period stated for

legumes, okra, and asparagus there are still present swollen seeds or

seeds of these kinds which have just started to germinate, all seeds

or seedlings except the hard and swollen seeds and seeds which have

just started to germinate shall be removed and the test continued for

5 additional days. Any normal seedlings which develop during this

period shall be included in the percentage of germination.

The percentage of hard seeds occurring in the germination test will

vary with the age, kind, variety, and moisture content of the samples.

There are some data to show that the hard seed content of some freshly

harvested legumes such as red clover, lespedeza, and field peas may

decrease rapidly within the first few weeks or months of dry laboratory

storage. Seeds of okra, vetch, and certa^in other legumes may increase in hard seed content during dry laboratory storage. It has

been found that hard seededness in beans is increased as the beans

become desiccated and that the relative humidity of the air in which

they are stored will cause rapid moisture changes within the seeds.

These changes are reversible. Some of the differences in reported

percentages of hard seeds on certain samples may be explained by

these facts.

Usually the analyst can easily distinguish between a swollen seed

and a hard seed. In cases of doubt, especially when testing large
TESTING AGRICULTURAL AND VEGETABLE SEEDS 101

seeds such as beans or peas, the questionable seed may be dropped on

a hard table top or china plate. Swollen seeds will produce a lowpitched thud whereas hard seeds will produce a higher-pitched ping.

If there is doubt as to whether a seed is swollen or dead, it should

not be destroyed by pressing with forceps but left in test with other

swollen seeds for 5 additional days. At the end of that period, the

dead seeds have usually decayed and the swollen seeds germinated.

Grasses such as Sudan grass often have firm, ungerminated seeds

left on the substrata at the end of the test period. These are not

to be confused with or reported as hard seed. It is possible that as

our knowledge of seed behavior increases such seeds may be treated

in some way to cause them to germinate. However, at the present

time, since these seeds do not respond to laboratory treatments under

the conditions now recommended in the rules, or to greenhouse soil

tests, they cannot be reported as having planting value.

METHODS OF OVERCOMING DORMANCY

SELECTING THE APPROPRIATE METHOD

Special treatments for overcoming dormancy are listed for many

kinds of seed in the rules for seed testing under "Remarks." Other

methods may be used by the analyst in cases where the method indicated for a particular'kind does not work. However, if the result

of such a test is reported the pretreatment should be indicated and the

report should also show the result obtained when tested in accordance

wdth the rules. It is necessary that the rules be kept as elementary

as possible and that the conditions of test be standardized. It would

be very desirable if only one germination condition could be specified

for each kind of seed, but owing to the complicated physiological

problems involved in seed germination, this is impossible for many

kinds. It has been found that as seeds age they frequently will not

only respond to different temperatures but they will lose the ability

to germinate rapidly at a temperature that was optimum when the

seed was fresh. It has also been found that seeds will often respond

to several combinations of conditions, and that one set of conditions

may be substituted for another. For example, light may compensate

for unfavorable temperatures, and potassium nitrate may stimulate

germination equally as well as light or soil.

LOW TEMPERATURES

Prechilling means placing the seed on a moist substratum at an

indicated low temperature for a specified period of time before placing

it at the higher temperature for the duration of the regular test period.

The temperature used most frequently in seed laboratories for prechilling is 10° C, although occasionally samples will be found requiring as low as 5° C. This is especially true for some of the native

grasses. Alternate methods in the rules of the Association of Oi&cial

Seed Analysts provide that certain of the cereals which may not

exhibit deep dormancy may be germinated satisfactorily at 15° C.

The proponents of this method claim that the prechiU period is

eliminated and the 15° temperature is satisfactory for nondormant

seeds' and will catch most dormant samples as well. This presents

a problem to the analyst to determine at which temperature to place
102 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

such samples. The age, origin, condition of samples, and other historical information will frequently help in determining the method

to be used.

HIGH TEMPERATURES.

Exposure to high temperatures has been found necessary for overcoming dormancy of some freshly harvested seeds. For example,

a constant temperature of 30° C. is specified in the rules for dormant

citron. There are some data which show that fresh seeds of other

cucurbits, peanuts, and tobacco may also respond favorably to high

temperatures. A constant temperature of 35° C. is specified in the

rules for Alyce clover, although data show that as the seed ages

it will respond to lower temperatures.

TEMPERATURE COMBINATIONS

Combination of low-high temperature alternations, with and without light, have been found to bring about as prompt germination of

some of the grass seed as can be obtained by prechilling. Freshly

harvested seeds of Canada bluegrass and Agrostis tenms will germinate more promptly at low-high temperature alternations, such as

10°-30° C. or 15°-30° C, than at 20°-30° C, Combinations of temperatures such as 10°-25° C. and 15°-25° C. without light have been

found to be optimum for dormant seeds of some of the fescues.

LIGHT

Light is specified in the rales for seeds of most of the grasses and

some of the vegetables. In the rules no distinction is made between

the light requirements of dormant and nondormant seeds. This is

because it is believed that moderate light exposure has no deleterious

effect on germination of nondormant seed, thus avoiding the necessity

of distinguishing between dormant and nondormant seed. There is a

wealth of data which show that light will overcome dormancy in certain kinds of seeds. There are also some data to show that the beneficial effects of light are tied up with the temperature at which the

moist seeds are held during the test period.

POTASSIUM NITRATE AND SOIL

Potassium nitrate solutions are known to stimulate the germination

of certain dormant seeds. Its use on particular kinds of seeds is indicated in the rules in the column under the heading "Remarks." A

0.2-percent solution is used in moistening the substratum except that

when testing Kentucky bluegrass and Canada bluegrass seed a 0.1-

percent solution is used. A 0.2-percent solution is prepared by dissolving 2 grams of potassium nitrate crystals in 1,000 cc. of distilled

water; a 0.1-percent solution is prepared by dissolving 1 gram of the

crystals in 1,000 cc. of distilled water. In rewatering the substrata

either tap water or distilled water should be used, and not a solution

of potassium nitrate.

Soil may sometimes be a better germination medium than an artificial substratum for the germination of certain dormant seeds. Its

use for particular kinds of seeds is indicated in the rules under the

column headings "Substrata" and "Remarks." In some cases either

potassium nitrate or soil may be used. Although it is known that

soil is sometimes a better substratum than an artificial medium mois-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 103

tened with a dilute solution of KNO3 the reason is not clearly

understood. Germination of rescue grass {Bromus catharticus) is

definitely higher when germinated in Petri dishes on soil than when

placed in Petri dishes on blotters moistened with a potassium nitrate

solution. There are some data to show that certain dormant oats may

germinate higher in soil than when placed betw^een folded towels.

Germination of orchard grass seed is usually more rapid in soil.

Germination of some of the grasses such as Western wheatgrass may

be higher and more uniform when soil is used as the substratum.

MODIFICATION OF THE SEED COAT AND OTHER STRUCTURES

Clipping the seeds of alfilaria, piercing the seed coat of Alyce clover,

degluming seeds of Bahia grass, and removing the pulp from seeds

(fruits) of New Zealand spinach are accepted methods of initiating

germination in these kinds of seed. These operations must be done

very carefully in order to avoid injury to the resultant seedlings. It

is known that other kinds of seeds listed in the rules will respond

to similar treatments but the analyst should not use such procedures

in service testing or on regulatory samples until such methods are

uniformly adopted.

STEEPING IN WATER

The rules provide that citron seed shall be soaked in water for 6

hours before testing and that dormant endive seed shall be "flooded'^

for 24 hours after which time the excess water is drained off. Also,

seeds of Beta vulgaris are to be soaked or washed in running water for

at least 2 hours to remove any toxic nitrogenous substances which ma}^

be present. There are provisions in the rules for maintaining a high

moisture level of the substratum when testing certain other kinds of

seeds. The analyst should observe these specific directions and follow

them closelv.

PREDRYING

Drying prior to testing is not included in the rules but has been

very effective in overcoming dormancy in grains with high moisture

content. The method used in the United Kingdom for cereal seed

provides for drying at a temperature of 40° C. for 3 days. In the

Federal laboratory cereal seed has been dried at 35° for 5 days with

good results.

SPECIAL PROCEDURES

FLUORESCENCE TEST ON RYEGRASS

The rules provide that when a fluorescence test is made on ryegrass the seedlings shall be grown on filter paper and the number of

fluorescent seedlings determined under the ultraviolet light at the

end of the germination period. The fluorescence test is used as a

means of measuring the presence and proportion of Italian ryegrass

in samples of perennial ryegrass seed. There is fairly conclusive

evidence that the roots of genetically pure perennial ryegrass do not

fluoresce, whereas the roots of Italian ryegrass do. The only reported

exception to this is that the roots of the annual, Wimmera ryegrass,

do not fluoresce. Wimmera ryegrass is of little or no economic value

in the United States. Hybrids of Italian and perennial ryegrass

may or may not fluoresce.
104 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

The present formula for calculating the results of fluorescence

tests makes an allowance of 5 percent for long-lived hybrids which

may fluoresce. The detailed procedure for placing the ryegrass seeds

for fluorescence test and the subsequent treatment and counting of the

seedlings is of utmost importance if uniform results are to be obtained.

Since the fluorescence occurs in the roots of the seedlings, enough

space must be allowed for growth of the roots without contact with

each other, or if planted close together arrangements must be made

to confine the roots of each seedling to a limited area. Filter paper

has been found to be a satisfactory substratum for development of

the fluorescent lines. The fluorescence not only shows on the roots

of the seedlings but also appears on the filter paper, outlining the

roots of each fluorescent seedling.

The exact placement and method of testing for fluorescence varies

considerably in laboratories, since the problem of space is often a

limiting factor. There are several methods In use which consist in

placing the seeds on: (1) Small strips of filter paper which are laid

flat on the germination tray; (2) strips of accordionlike folded filter

paper or on flat pieces of filter paper which are then placed sidewise

in a daylight germinator so that all roots will grow in the same direction; (3) filter paper pressed into cuplike depressions in a flat plastic

board, with the aim of restricting the roots of each seedling to a

single depression; (4) filter paper in Petri dishes; and (5) squares of

filter paper laid flat on germination trays.

In Petri-dish tests there is a tendency to crowd the seeds too close

together. The fluorescent seedlings are removed daily or as soon as

the fluorescent lines become apparent. This usually occurs about the

sixth day of test and may continue to appear until the sample has

fully germinated.

The method employed in the Federal laboratory at Beltsville is

identified as method (5) above and is used as follows: The seeds are

tested in 8 replicates of 50 seeds each. The substratum for each

replicate consists of 2 square pieces of filter paper cut approximately

9 by 9 inches placed directly upon 2 pieces of blotting paper cut the

same size. Four of these replicates fit on the standard germination

tray, thus making it necessary to use 2 trays for the complete test.

The seeds are placed on the substratum with the aid of a vacuum

counter which insures a spacing of approximately 1 inch between

seeds. The trays are placed in a 20°-30° C. daylight germinator.

The tests are examined for fluorescence at the end of the 14-day

test period. The dead seeds are circled with an indelible pencil before

the tests are placed under the ultraviolet light. Time is allowed for

the analyst's eyes to become accustomed to the ultraviolet light and

then the roots on each seedling showing fluorescence are outlined on

the filter paper with an indelible pencil. Any seedlings not showing fluorescence are pulled off the filter paper while being held under

the ultraviolet light in order to detect fluorescence from roots which

may have grown into the substratum. A blue line or faint trace of

fluorescence will often be evident when the seedlings are thus examined.

The percentages of fluorescence, nonfluorescence, germination, and

dead seeds should be ascertained and recorded on the record card.

The procedure for calculating the results, with examples, is given

on page 64. The percentages of fluorescence and germination are both

obtained from the same test.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 105

TESTING COATED OR PELLETED SEED

The methods of pelleting and coating seeds and problems incident

to testing such seed have been discussed under the heading "Procedures

for Determining Purity Composition."

Whether the inert "covering" would have to be removed from the

seeds before a germination test is made has not been determined.

Probably such 'pellets" can be germinated according to the present

provisions for temperature, butitis questionable whether artificial substrata can be used successfully. There are some data which suggest

that a more natural medium such as sand or soil will be necessary for

proper germination and seedling evaluation. Other data indicate

that injury to the seed, as reflected in its germination, may occur during the "pelleting" process. Also, the inert covering appears to retard

germination of some kinds of seed.

THE COLD TEST

The rules for testing seeds aim to provide optimum conditions for

the germination of each kind to be tested. It has been advocated that

in addition to the standard germination test another test should be

made under adverse growing conditions similar to the unfavorable

conditions which may prevail in the field subsequent to planting.

This method, commonly known as the ''cold test," is intended to detect

weaknesses and measure the seeds' response to these unfavorable field

conditions. At the present time the cold test is limited essentially to

corn, although it is understood that the method is being used for beans

and peas on a small scale. Briefly, the method for corn consists in

planting the seeds in unsterilized soil or a mixture of soil and sand,

with high-moisture content, at a temperature of approximately 10° C.

for 5 to 7 days and then transferring the tests to a temperature of

approximately 30° C. for completion. Sorne laboratories use loam

soil from a cornfield without further inoculation whereas other laboratories inoculate the soil with ground seed which previously failed to

germinate. The difficulties of standardizing such tests are apparent,

and their future use as regular laboratory methods is unpredictable.

SPECIAL METHODS OF DETERMINING VIABILITY

The use of biochemical methods as rapid measures of determining

seed viability are still in the experimental state. Their use is based

on the principle that certain compounds such as selenium and

tetrazolium are reduced to colored forms by enzymatic action in living

cells and that no staining will occur in dead cells.

The use of selenium salts has been discouraged because of their

toxicity to the individual carrying out the test. The use of tetrazolium compounds as a regular method of determining viability has apparently been limited to certain laboratories in Germany, where it was

first developed. Investigations are currently being conducted in the

United States, England, and perhaps other countries, but present indications are that the method can be used only as a rough measure of

seed viability. Apparently, very high germinating seed will stain

easily and dead seed will not stain, but the correlation between staining and germination of seed of intermediate viability and of low vigor

is very poor. Obviously, a staining test does not directly measure

the plant-producing power of seeds which may be diseased, mechanically injured, or insect-damaged.
106 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

The activity of such enzymes as catalase and oxidase as a measurement of seed viability has been reported by numerous workers. The

conflicting data and the fact that the determinations require special

equipment have made their application to seed testing of no practical

importance.

The growth of excised embryos, as a rapid method of measuring

seed viability, is of more practical application to nurserymen and

foresters than to seed analysts. Because of the difficulty of removing

embryos without injury, the small size of most of the seeds subject to

the rules for testing, and the relatively short periods required for a regular germination test this method has found no place in the testing

of agricultural and vegetable seeds. There is no provision for the

excision of embryos in the present rules.
APPLICATION OF GERMINATION PROCEDURES TO

SPECIFIC GROUPS

AIZOACEAE (CARPETWEED FAMILY) AND CHENOPODIACEAE

(GOOSEFOOT FAMILY)

KINDS OF SEED

Aizoaceae—Carpetweed family.

New Zealand spinach—Tetragonia expansa.

Chenopodiaceae—Goosefoot family.

Beet—Beta vulgaris.

Sugar beet—Beta vulgaris var. saccharifera,

Swiss chard—Beta vulgaris var. cicla.

Mangel (field)—^eia vulgaris.

Spinach—Spinacia olerácea.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Neio Zealand spinach,—New Zealand spinach seed is frequently

dormant. Exposure of the fruits to low temperatures or removal of

the pulp from around the ends of individual seeds in each fruit will

cause prompt germination. The laboratory treatments for breaking

such dormancy are : Germination of the fruits on top of soil at alternating temperatures of lO^-SO"^ C, or removal of the pulp from the

fruits and then placing them for germination between blotters at 15°.

Extreme care must be taken when the pulp is removed so as not to

injure the seeds. The rules also specify that the substratum should

be kept somewhat drier than it is maintained for the average kind of

seed. It has been claimed that the absorption of excess water by the

pulp of the fruit can cause "water-logging" or restriction of the aeration necessary for germination. The Federal laboratory has had success in regulating the moisture on New Zealand spinach by pressing

the seeds about half their length into the top of soil, keeping the substratum fairly dry, alternately rewatering, stirring the soil, and turning the fruits during the course of the test period.

Spinach.—Spinach, Spinacia olerácea.^ may exhibit dormancy if

germinated at too high a temperature, or if the seeds are kept too

wet during the test period. No difficulty with dormancy should be

experienced if the provisions of the rules with respect to temperature

and moisture are followed. The seeds should be placed on top of

blotters at 10° C. and kept slightly dry. In no case should water be

allowed to accumulate around individual seeds. Germination has

been found to be accelerated if the seeds are placed at 15° C, but

as yet there is no provision in the rules for such treatment.

Beta vulgaris.—Slight dormancy frequently occurs in the diife^rent

varieties of Beta vulgaris. This has been attributed to the mechanical

restriction of the enveloping seed structures and the presence of germination inhibitors in the seed balls. Treatments with sulfuric acid,

soaking in water, and germinating in soil have been recommended

957116—52: 8 107
108 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

for such samples. Soaking in water is specified in the rules as the

laboratory treatment for all the varieties of beet. The procedure is

as follows : Soak in water for 2 hours, using at least 250 cc. per 100

balls; rinse in running water and blot the surface of the balls dry.

After the seeds have been soaked, rinsing may be accomplished by

dumping them into a fine meshed colander or sieve and washing them

under running water in a sink. They can then be placed on a piece

of absorbent toweling and the excess moisture blotted off. Then they

may be rolled up in a dry towel and left for a few minutes, unrolled

and put in test with the aid of a mechanical counter.

After germination is initiated in beets the seedlings may become

black and die, owing to the presence of toxic substances from the

seed balls coming in contact with the young sprouts. The soaking

process as described above ordinarily removes most of these substances

or germination inhibitors from the seed balls. However, occasional

samples may be found which will have darkened radicles or hypocotyls, or both, in blotter tests. In soil tests there is very little blackening of seedlings since the toxic substances are apparently adsorbed

by the soil particles. For these occasional samples with blackened

seedlings in the blotter tests, the following treatments are recommended in the rules : Eetest either in sand or soil or by washing in

running water for 3 hours and then placing the seed balls on creped

cellulose paper wadding, keeping the seed covered with slightly moist

blotters. Special equipment as that described on page 35 is necessary if the seeds are washed in running water.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Blotters,—The different varieties of Beta vulgaris are tested between blotters and also New Zealand spinach when the pulp has been

removed. No more than 50 seeds should be placed on a blotter folded

to 4% by 6 inches in size.

If the fruits of New Zealand spinach are to be tested between blotters, the pulp should be scraped off in a manner that will not cause

injury to the seeds which lie near the surface of the large end of the

fruit. To facilitate removal of the pulp soak the fruits in water for

a few hours. No particular precautions need be observed in scraping

the base and sides but the broad end should be observed with a hand

lens occasionally to determine whether there is injury to the seeds or

whether some have been accidentally removed.

Spinach seed is tested on top of blotters. No more than 100 seeds

should be placed on a blotter 43^4 by 6 inches in size. The edges should

be turned up approximately % inch to prevent the seeds from rolling.

Band and 5ö^7.—Sand or soil is indicated as an alternate method

for seeds of Beta vulgaris exhibiting darkened radicles in blotter

tests. It has been found that testing in sand or soil is an invaluable

guide for proper interpretation of seedlings from balls infected with

Phoma^ overrun with mold, or mechanically injured by the shearing

process. In no case should more than 100 beet balls be placed in a

container 81/2 by 8y2 by 1% inches in size. Separators constructed to

provide a separate section for each seed ball should be used when soil

or sand tests are made.

The rules provide for testing New Zealand spinach seed on top ot

soil or sand. Since the test period for intact fruits is of long dura-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 109

tion, a substratum that will retain moisture over a long period of time

and yet not pack with rewatering is desirable. Equal amounts of

sand, soil, and peat moss have been found very satisfactory. The

fruits should be firmly pressed into the substratum for at least onehalf their length. No more than 25 fruits should be placed in a container 41/^ by 4% by li/¿ inches in size. This requires 16 replicates

for a complete test.

Creped cellulose wadding.—Kimpak is indicated as an alternate

method for Beta vvlgaris and varieties if they exhibit darkened

radicles in blotter tests. No more than 50 seeds should be placed on

a piece of creped cellulose paper wadding 9 by 9i/^ inches in size.

Seventy-five cc. of water should be added to a piece of Kimpak this

size. A moist blotter the same size should be placed over the seeds.

SEEDLING INTERPRETATION

Since the seed unit in beet, sugar beet, mangel, Swiss chard, and

New Zealand spinach usually contains more than one seed, the germination percentage is based on the number of viable seed balls or

fruits and not on the number of viable true seeds. Even though two

or more seedlings develop from each seed unit, only one is counted.

The only exception is when a sprout count is requested for beets. In

this case both the germination of each fruit or seed "ball" and of the

seedlings per "ball" are recorded and reported.

A completely normal seedling on the above kinds should have a

long slender root with root hairs, a long, well-developed hypocotyl,

two attached leaflike cotyledons and an intact but small epicotyl. It

is not possible to observe the condition of the epicotyl in routine testing. The condition of the cotyledons must be observed, especially

when mechanical injury to the seed is apparent. (Figs. 24, 25, 26.)

Normal seedlings include those that have: (1) A well-developed,

long, slender root with root hairs; (2) a stubby primary root, provided

the secondary roots are strong and the hypocotyl is near normal length,

as in spinach; (3) at least one attached cotyledon, provided the seedling is otherwise normal; (4) slight infection by fungi, provided none

of the essential seedling structures have been damaged; (5) normal

seedling structures of Beta but discolored from toxic substances in

the seed balls or other causes; (6) at least one normal seedling from

a seed ball, regardless of whether abnormal seedlings also emerge

from the same fruit.

Abnormal seedlings include those that have: (1) No root or a

stubby primary root with poor secondary root development, usually

associated with a shortened hypocotyl; (2) a malformed, shortened,

twisted, watery, or stubby hypocotyl, usually associated with a stubby

root but not necessarily so; (3) deep grainy lesions or cracks in the

hypocotyl if they appear to interfere with the conducting tissues;

(4) both cotyledons absent as in samples of "sheared" beets and occasional samples of spinach; (5) two large cotyledons, but a malformed, short hypocotyl, usually with a stubby root; (6) decayed

cotyledons or hypocotyl, provided they are not the result of improper

test conditions (if there is decay of beet seedlings in blotter tests the

results from a properly conducted soil or sand test should be accepted

as correct) ; and (7) various combinations of the above abnormal

types.
lio AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

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112 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

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TESTING AGRICULTURAL AND VEGETABLE SEEDS 113

COMPOSITAE (COMPOSITE OR SUNFLOWER FAMILY)

KINDS OF SEED

Artichoke—Cynara scolymiis,

Cardoon—Cynara carduncnlus.

Chicory—Ciohorium, intyhus.

Dandelion—Tarawacu7n ofßcinale.

Endive—Cichorium endivia.

Lettuce—Lactuca sativa.

Salsify—Tragopogón porrifolius.

Sunflower (cult.)—Helianthtis annuiis.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Since the pure seed units of the composite family may include

empty "seeds^' or fruits, analysts must distinguish between low germination owing to unfilled seeds and that owing to dormancy. It

is recommended that at the end of the germination test all ungerminated seeds should be examined to determine whether they are empty,

dead, or dormant. Empty fruits occur more frequently in samples

of endive and chicory than in the other kinds.

Dormancy may be encountered in the laboratory testing of endive,

chicory, lettuce, salsify, and possibly dandelion. It is unlikely that

it will occur in artichoke, cardoon, or sunñower. Although the seeds

of endive and chicory are practically indistinguishable, endive will

often exhibit extreme dormancy whereas chicory will not. Data on

germination of endive show that the seeds will respond favorably

to treatment with excess moisture and solutions of thiourea. Germination in the laboratory is usually higher when the substratum

is moistened with a dilute solution of potassium nitrate or when the

seed is germinated on top of soil, both of which are specified as

regular methods for endive and chicory. In addition, dormant seeds

of endive should be subjected to an excess of water during the first

part of the test period. Care must be taken not to submerge the

seeds but to carefully add about one-eighth inch of water to the substratum. This can be accomplished by lifting off the upper layer

of artificial substratum which contains the seeds, adding the water

to the Petri dish, and then carefully replacing or "floating" the top

layer of substratum with the seeds on the water. Certain varieties

of lettuce may be extremely dormant and will usually respond to such

treatments as light, soaking in water, and prechilling. Exposure to

light and prechilling of dormant seeds are specified as regular laboratory germination procedures.

Light is specified in the rules for dandelion although no dormant

samples have been observed in the Federal laboratory. Dormancy in

salsify has been shown to be broken by prechilling, the method specified in the rules.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Folded towel tests are indicated in the rules for artichoke, cardoon,

salsify, and sunflower, although indications are that upright rolled

tests would be more satisfactory. In no case should more than 50

seeds of any of the above kinds be placed in a folded towel approximately 51/^ by 7 inches in size. If upright rolled towels of approximately li by 14 inches in size are used, no more than 50 seeds of artichoke, cardoon, or sunflower or 100 seeds of salsify should be placed
114 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

in each towel. If sunflower seed is tested between folded blotters,

no more than 50 seeds should be placed in a blotter folded to 43/ by 6

inches in size.

The rules list Petri-dish tests as standard for endive, dandelion,

chicory, and lettuce, but dandelion may be tested on top of blotters

and endive and chicory on top of soil or sand. No more than 100 seeds

of the above kinds should ever be placed in 100- or 120-mm. Petri

dishes or in boxes 4i^ by 4I/2 by 11/2 inches in size.

SEEDLING INTERPRETATION

By the end of the germination test, a perfectly normal seedling

belonging to the composite family should have a well-developed

root with root hairs, a long and well-developed hypocotyl, two leaflike

cotyledons, and a small but visible epicotyl. It will not be possible

or practical to observe the epicotyl development on any of these kinds

of seeds except those tested in soil and abnormal seedlings on artificial

substrata (such as result from mechanically injured sunflower seed)

that are not removed until the final count is made. The epicotyl

development on lettuce is still very small at the end of 7 days. (Fi^s.

27-30.) ^ ^

Leétuce,~ThQ interpretations of lettuce seedlings are made only at

the end of the test period. (Figs. 27, 28, 29.)

Normal seedlings include those that have: (1) A well-developed,

long, slender root with root hairs ; (2) a well-developed long hypocotyl

with no deep lesions which might interfere with the conducting tissues; (3) two green cotyledons with some blackened or reddish-brown

areas, provided the hypocotyl and roots have developed normally or

approximately so; and (4) slight infections by fungi, provided none

of the essential seedling structures have been damaged.

Abnormal seedlings include those that have: (1) No roots, or very

stubby or shortened roots, which are usually associated with shortened

hypocotyls; (2) shortened hypocotyls which are usually associated

with stubby roots; (3) malformed hypocotyls, severely twisted or

having grainy areas or cracks extending into the conducting tissues;

(4) cotyledons with large areas of blackish or reddish-brown tissue,

usually appearing along the midrib, associated with a short hypocotyl

and root (the seed coats are often attached to the cotyledons, adhering

to the darkened areas and they may be removed by sprinkling them

with water and then manually pulling or brushing them off) ; (5)

cotyledons with a gray cast over their entire area, usually darker

at the midrib section (hypocotyls and roots invariably shortened and

seed coats usually attached to the cotyledons) ; (6) swollen, blackened

cotyledons with only vestiges of hypocotyl and root, the seed coats

usually remaining attached to the cotyledons ; (7) decayed cotyledons.

Other co7nposites,~Th.is group includes artichoke, cardoon (fig. 30),

sunflower, salsify, dandelion, chicory, and endive.

Normal seedlings include those that have: (1) A well-developed,

long, slender primary root with root hairs; (2) a stubby root if there

are one or more strong secondary roots, provided the seedling is otherwise normal; (3) a well-developed, long, hypocotyl with no prominent breaks or deep lesions which might interfere with the conducting

tissues; (4) at least one uninjured cotyledon, provided the epicotyl

is also present; (5) slight infection of the roots or hypocotyl with
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FiGUBE 27.—Lettuce {Lactuca sativa). Normal and abnormal seedlings from 7-day tests in soil.

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FiGUBE 29.—Lettuce {Lactuca sativa). Normal and abnormal seedlings from 10-day tests in greenhouse.
118 AGRICULTURE HANDBOOK NO. 30, V. S. DEPT. OF AGRICULTURE

FIGURE 30.—Cardoon {Cynara cardunoulus). Normal and abnormal seedlings

from 14-day tests in towels.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 119

fungi, provided none of the essential seedling structures have been

damaged.

Abnormal seedlings include those that have : (1) No root or a stubby

root with weak secondary' roots, usually associated with a shortened

hypocotyl; (2) a malformed hypocotyl, which may be curled, shortened, or thickened, usually associated with a stubby root; (3) deep,

unhealed cracks or grainy areas on the hypocotyl, extending into the

conducting tissues; (4) both cotyledons entirely broken off; (5) one

cotyledon broken off, provided the epicotyl is also absent; (6) two

normal cotyledons with a short malformed hypocotyl, usually with

a stubby root; (7) decayed cotyledons, provided the infection is not

caused by improper test conditions; and (8) various combinations of

the above-named abnormal types.

CRUCIFERAE (MUSTARD FAMILY)

KINDS OF SEED

Broccoli—Brassica olerácea var. 'botrytis.

Brussels sprouts^—B. olerácea var. gemnifera.

Cabbage—B. olerácea var. capitata.

Cauliflower—B. olerácea var. hotrytis.

CoUards—B, olerácea var. acephala.

Cress, garden—Lepidium sativum.

Cress, water—Rorippa nasturtium-aquaticum.

Kale—Brassica olerácea var. acephala.

Kohlrabi—B. olerácea var. gongylodes.

Mustard :

Black—Brassica nigra.

White—B. hirta.

India or Southern curled—B. júncea.

Spinach—B. perviridis.

Pakchoi—B. chinensis,

Pe-tsai—B. pekinensis.

Radish—Raphanus sativus.

Rape:

Annual—Brassica napus var. annua.

Bird—B. campestris.

Turnip—B. campestris vars.

Winter—B. napus var. diennis.

Rutabaga—B. napus var. napohrassica.

Turnip—B. rapa.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Dormancy may occur in many of the kinds in this group, especially

those of the genus Brassica, Proper identification of the species being

tested must be made and the appropriate treatment selected for germination. Low germination results may be obtained if seeds are incorrectly identified and subsequently not placed under recommended

conditions for breaking dormancy.

Of the mustards, B, júncea (Southern curled or India), and B. nigra

(black mustard) are apt to be dormant, whereas B. hirta (white mustard) and B. perviridis (Spinach mustard) are not. Seeds of the

B, olerácea group (broccoli, brussels sprouts, cabbage, cauliflower,

coUards, kale, and kohlrabi) are occasionally dormant. The use of

potassium nitrate, light, and prechilling are recommended in the rules

for overcoming dormancy in these kinds.

Dormancy may also be encountered in B, campestris (bird rape).

Treatment with potassium nitrate only is recommended in such in-
120 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

stances. It is unlikely that dormancy will be found in B, napus var.

annua (annual rape), B, campestris vars. (turnip rape), B. napus

var. hiemds (winter rape), B, napus var. napolrassica (rutabaga),

B. pehinensis (pe-tsai), B. chinensis (pakchoi), or B. rapa (turnip).

There is a provision in the rules for treating dormant samples of

garden cress (Lepidium sativum) by placing them at 15° C. in light.

There is no provision for breaking dormancy of water cress, Rorippa

nasturtium-aquaticum^ although it has been observed in some samples.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Seeds of most of the crucifers or members of the mustard family

may be tested between blotters. In no instance should more than 50

seeds of radish or 100 seeds of any of the other kinds be placed in a

blotter folded to 4=% by 6 inches in size. Since these seeds roll easily,

the edges of the blotters should be turned up about i^ inch. No more

than 100 seeds of any species of the Cruciferae should be tested in a

100-mm. Petri dish.

SEEDLING INTERPRETATION

By the end of the germination test, a perfectly normal crucifer

seedlin^g should have a well-developed root, usually with root hairs, a

long hypocotyl, two intact green, leaflike cotyledons and a small but

visible epicotyl or growing point. Except for diseased seedlings of

radish and Brassica it is not practical to observe the epicotyl development, unless samples are tested in soil, in which case the cotyledons

will open and the growing point become clearly visible. However,

the cotyledons of diseased radish and Brassica seedlings must be observed, in which case the seedlings should not be removed until the

extent of the decay can be determined. It is usually necessary to use

a hand lens for these close observations. (Figs. 31, 32, 33.)

Radish {Raphanus sativus) and Brassica spp,—ltiBi[\ot])mQ^i\Q.dXio

observe the epicotyl except in soil tests or on diseased samples of

radish. (Figs. 31, 32, 33.) .... .

Normal seedlings include those that have: (1) A well-developed,

long, slender primary root with root hairs; (2) a well-developed, long

hypocotyl with no prominent breaks or deep lesions which might

interfere with the conducting tissues; (3) one or two cotyledons not

decayed at the point of attachment to the hypocotyl, provided the

epicotyl is also present; (4) slight decay at the base of one cotyledon,

provided the epicotyl is not infected; (5) less than 50 percent of the

area of the cotyledons covered with spots or darkened areas; and (6)

slight infection of roots or hypocotyl with fungi, provided none of

the essential seedling structures have been damaged.

Abnormal seedlings include those that have : ( 1 ) No root or a stubby

root, usually associated with a shortened hypocotyl; (2) a malformed

hypocotyl, which may be curled, shortened, or thickened and usually

associated with a stubby root; (3) deep, imhealed cracks or lesions

(often grainy) on the hypocotyl, extending into the conducting tissues; (4) decay at the point of attachment of both cotyledons to the

hypocotyl which may or may not involve the terminal bud; (5) decay

atthe point of attachment of one cotyledon to the hypocotyl, provided

the terminal bud is also decayed; (6) 50 percent or more of the area

of the cotyledons covered with spots or darkened areas; (7) decayed
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FIGURE 31.—Cabbage (Brassica olerácea var. capitata). Normal and abnormal seedlings from lO-day tests lu

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FIGURE -Radish (Rapluinug satlvus). Normal and abnormal seedlings from 6-day tests

between blotters.

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124 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

roots or hypocotyls, provided the infection was not caused by improper

test conditions ; (8) watery hypocotyls (usually associated with some

other abnormality of the seedlings), provided this condition is not

caused by excessive moisture of the substratum; and (9) various combinations of the above-named abnormalities.

Garden cress {Lepidimn sativmn) and water press {Rorippa nasturtium-aquaticum) .—There appears to be very little difficulty in distinguishing between normal and abnormal seedlings of garden cress

and water cress.

Normal seedlings include those that have: (1) A well-developed,

slender root with root hairs; (2) a long, Avell-developed hypocotyl

with no prominent breaks or deep lesions which might interfere with

the conducting tissues ; (3) intact cotyledons ; and (4) slight infection

with fungi, provided none of the essential seedling structures have

been damaged.

Abnormal seedlings include those that have: (1) No root, or a

stubby root, usually associated with a shortened hypocotyl; (2) a

malformed hypocotyl, which may be curled, twisted, shortened, or

thickened and frequently associated with a stubby root; (3) deep,

imhealed cracks or grainy lesions on the hypocotyl, extending into

the conducting tissues ; (4) watery hypocotyls, usually associated with

stubby roots or decayed cotyledons; (5) cotyledons entirely broken

off; (6) decayed cotyledons, provided the infection was not caused

by improper'test conditions; and (7) various combinations of the

above-named abnormal types.

CUCURBITACEAE (CUCURBIT FAMILY)

KINDS OF SEED

Citron—Citrullus vulgaris.

Watermelon—Citrullus vulgaris.

Cacumber—Cucumis sativus.

Muskmelon or cantaloup—Cucumis melo.

Pumpkin—CucurUta pepo.

Squash—CucurUta moschata and C. maxima.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Dormancy may occur in freshly harvested seeds of cucurbits although there is no provision in the rules for the laboratory treatment

of this condition except for citron. It has been observed that the extent of dormancy varies not only with the kinds but also with the

varieties. Exposure of seeds to a higher constant or alternating temperature than provided in the rules and removal of the seed coats

have been used successfully to overcome dormancy in certain of these

cucurbits.

Unless the substrata for watermelon, cucumber, muskmelon or

cantaloup, pumpkin, and squash are kept drier than they are mamtained for the average kind of seed, secondary dormancy may occur.

The seeds are very sensitive to excess moisture.

The rules provide that citron should be soaked 6 hours before being

placed for test and that dormant samples should be placed at 30° C.

for the duration of the test period.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 125

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Cucumber and muskmelon or cantaloup are tested between blotters.

No more than 50 seeds should be placed in a blotter 4% by 6 inches

in size.

Folded towels are used for citron, watermelon, pumpkin, and squash

and also as an alternate substratum for cucumber and muskmelon

or cantaloup. Upright rolled towels may be just as satisfactory provided they are kept on the dry side. No more than 50 seeds of citron,

watermelon, cucumber, muskmelon or cantaloup and no more than

25 seeds of pumpkin or squash (large seeded) should be placed in

towels folded to 5% by 7 inches in size. If upright rolled towels are

used, 50 seeds of all kinds may be placed in rolls approximately

11 by 14 inches in size.

It is permissible to use soil and sand as alternate substrata for

watermelon, cucumber, muskmelon or cantaloup, pumpkin, and squash.

No more than 50 seeds of the small-seeded kinds should be placed

in a container 4% by 4% by 1% inches in size and no more than 50

seeds of the large-seeded kinds in a container 8% by 8I/2 by 1% inches.

SEEDLING INTERPRETATION

The cucurbits considered herein all exhibit epigeous growth, the

cotyledons turning green and serving not only as food storage but as

manufacturing organs. By the end of the germination test a perfectly normal seedling should have a well-developed primary root

with'several secondary roots, a long hypocotyl, two intact cotyledons,

and an epicotyl or terminal growing bud. Unless soil or sand tests

are made, the analyst will not be able to observe the condition of the

epicotyl. (Fig. 34.)

Normal seedlings include those that have: (1) A well-developed

primary root with or without secondary roots; (2) a stubby primary

root with at least two strong and vigorous adventitious roots, provided the hypocotyl is not shortened very much; (3) a long well-developed hypocotyl; (4) two intact cotyledons ; and (5) slight infection

by fungi, provided none of the essential seedling structures have been

damaged.

Abnormal seedlings include those that have: (1) No primary root,

a stubby primary root, or a stubby primary root with weak secondary

roots which are usually associated with a short hypocotyl; (2) a

malformed hypocotyl which may be shortened or thickened ; (3) thickened and shortened hypocotyls and roots owing to injury from chemical treatment, provided the injury is still apparent in a soil or sand

check test; (4) decayed cotyledons or other essential seedling structures, provided the decay was not the result of improper test conditions; and (5) various combinations of the above-named abnormal

types.
126 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FIGURE 34.- -Cucumber {Ciicumis sativus). Normal and abnormal seedlings

from 7-day tests in towels.

GRAMINEAE (GRASS FAMILY)

KINDS OF SEED

The iiiforniation in the text for groups such as cereals, millets, and

grasses will apply to all the kinds herein listed for each group unless

otherwise specified.

Cereals:

Barley—Hordeum vulgäre.

Oat—Avena sativa and A. iyzaiitina.

Rye—Sécale céréale.

Wheat—Tritioutn spp.

Rice—Oryza sativa.

Corn, field—Zea mays.

I'opcorn—Zea mays var. everta.

Sweet corn—Zea mays var. sacoharata.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 127

Millets :

Browntop—Panicuni ramosum (see footnote, p. 397).

Foxtail—Common, German, Hungarian, Siberian, or Golden—Setaria itálica.

Japanese—Echinochloa crusgalli var. frumentacea.

Pearl—Pennisetum glaucum.

Proso—Panicum miliaceum.

Sorghums :

Grain and Sweet (Sorgo)—Sorghum, vulgäre.

Broomcorn—Sorghum sudanense {S. imlgare var. technicum).

Sudan grass—Sorghum vulgäre var. sudanense.

Typical grass groups—(More than one species to a genus—mostly small seeded) :

Bentgrass : Colonial—Agrostis tenuis.

Astoria—Agrostis tenuis var.

Highland—Agrostis tenuis var.

Creeping (seaside)—Agrostis palustris.

Velvet—Agrostis canina.

Bluegrass:

Annual—Poa annua.

Bulbous—Poa hulhosa.

Canada—Poa compressa.

Kentucky—Poa pratensis.

Nevada—Poa nevadensis.

Rough—Poa trivialis.

Texas—Poa arachnifera.

Wood—Poa nemoralis.

Bromes :

Mountain—Promus marginatus.

Smooth—Promus inermis.

Bluestems :

Big—Andropogon gerardi {A. furcatus).

Little—Andropogon scoparius.

Sand—Andropogon hallii.

Fescues :

Chewings—Festuca ruhra var. commutata.

Hair—Festuca capillata.

Meadow—Festuca elatior.

Red—Festuca rudra.

Sheep—Festuca ovina.

Tall—Festuca arundinacea.

Grama :

Blue—Bouteloua gracilis.

Side-oats—Bouteloua curtipendula.

Ryegrasses :

Italian—Lolium multiflorum.

Perennial—Lolium perenne.

Wheatgrasses :

Crested (Fairway and standard)—Agropyron cristatum.

Slender—Agropyron pauciflorum.

Western (Bluestem)—Agropyron sniithii.

Other typical grasses—(Mostly small seeded) :

Bahia grass—Paspalum notatum.

Bermuda grass—Cynodon dactylon.

Buffalo grass—Buchloe dactyloides.

Canary grass—Phalaris canariensis.

Canary grass, reed—Phalaris arundinacea.

Carpet grass—Aœonopus afßnis.

Crested dogtail—Cynosurus cristatus.

Dallis grass—Paspalum dilatatum.

Dropseed, sand—Sporol)Olus cryptandrus.

Guinea grass—Panicum maximum.

Harding grass—Phalaris tuberosa yar. stenoptera.

Indian grass, yellow—Sorghastrum, nutans.

Japanese lawngrass—Zoysia japónica.

Johnson grass—Sorghum halepense.

Lovegrass, weeping—Eragrostis curvula.

Manila grass—Zoysia matrella.
128 AGRICULTURE HANDBOOK NO. 3Ô, Ü. Ö. t)EPT. OF AGRICULTURE

Other typical grasses—Continued.

Meadow foxtail—Alopecurus pratensis.

Molasses grass—Melinis minutiflora.

Napier grass—Pennisetum purpureum.

Oatgrass, tall—Arrhenatherum elatius.

Orchard grass—Dactylis glomerata.

Panic grass, blue—Panicum antidotale.

Redtop—Agrostis alha.

Rescue grass—Bramus catharticiis.

Rhodes grass—Ghloris gayana.

Ricegrass, Indian—Oryzopsis hymenoides.

Smilo—Oryzopsis miliacea.

Sweet vernal grass.—Anthoopanthum odoratum.

Switch grass—Panicum virgatum.

Timothy—Phleum pratense.

Vasey grass—Paspalum urvillei.

Velvet grass—Holcus lanatus.

Wild rye, Canada—Elymus canadensis.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Dormancy may be encountered in testing most of the Gramineae

listed in the rules.

Barley^ oats^ rye^ wheat,—Barley, oats, rye, and wheat respond

to the same general temperature conditions, although some samples

of oats may exhibit dormancy diíBcult to overcome in the laboratory.

The regular treatment for dormant samples of seeds in the abovelisted cereals is to prechill them at 5° or at 10° C. for 5 days, and

then place them at 20° C. Since dormancy in the majority of these

kinds appears to be easily overcome by subjecting the seeds to temperatures just below 20° C, an alternate method of testing is to place

them at 15° C. for the duration of the test period. The selection

of the method to use will depend on the kinds and condition of the

samples regularly received in each laboratory. If dormant seeds remain at the end of the test period, retests should be made under some

other condition. Certain samples of dormant oats may require special

treatment, such as placement at 5° C, in a soil substratum, or predrying. The latter procedure is not in the rules, but it is generally

accepted that either slow drying at about 35° or 40° C. for 3 to 7 days,

or the natural drying after receipt and storage in laboratories, will

often overcome dormancy in cereals.

Rice.—Dormancy may be encountered in the testing of rice, although there is no provision in the rules for overcoming this condition.

Some available data indicate that a substratum providing more moisture than is provided by folded blotters or folded towels would tend

to overcome this dormancy. Upright rolled towel tests with a large

initial moisture supply and flooded sand tests have proved very successful.

Millets.—Although dormancy in the millets is not mentioned in the

rules, it has been occasionally observed in those of the genera Panicum

and Setaria, Lack of data makes it impossible to suggest a method

of overcoming this condition. However, if an analyst is not sure

whether a sample is dead or dormant, the glumes may be carefully

removed from the seeds and the naked caryopses put back in test.

If the seed is dead, the embryos will turn dark and decay within a

few days.

Sorghunns and Sudan grass.—Dormancy in sorghums may be overcome by prechilling at 5° or 10° C. for 5 days. There are data to
TESTING AGRICULTURAL AND VEGETABLE SEEDS 129

show that slow drying or that testing certain of the sorghums at 20°-

35° C. instead of at 20°-30° C. might also have a beneficial effect but

these methods should not be used unless the official rules are found

inadequate. Common Sudan does not appear to exhibit dormancy,

although it is possible that Sweet Sudan might. However, there is

little information on this subject at the present time.

Grasses,—In order to standardize and simplify the methods of

testing, the least possible choice of treatments and substrata have been

included in the rules for the different grass species. Light is specified

for all the grasses except Napier grass, canary grass, and certain of

the fescues. If red and Chewings fescues are germinated at the specified alternate method of 20°-30° C. instead of the regular method of

15°-25° C, light must be used. It has been found that the lower

temperature alternation is more favorable for the germination of

freshly harvested seed. When such seed is placed at the higher temperature light appears to compensate for the unfavorable temperature

condition.

The temperature alternations and prechilling treatments in the rules

are very specific and should need no further explanation beyond stressing that lack of correct temperature control may cause samples of

grasses to exhibit erratic germination or no growth at all or to be

thrown into secondary dormancy.

The use of potassium nitrate solutions and/or soil for overcoming

dormancy in certain grasses is indicated in the rules. Potassium nitrate is preferred and used in most laboratories for routine testing.

Soil is better than an artificial substratum moistened with a potassium

nitrate solution in the following cases : (1) When there is root injury

resulting from the use of potassium nitrate; (2) when certain grasses

need an extraordinarily long time for completion of germination;

(3) when slow germinating orchard grass seed is encountered ; and (4)

when rescue grass seed is tested with the glumes remaining on. Rescue grass seed will germinate very rapidly if deglumed, and the

caryopses scratched and moistened with potassium nitrate and placed

at 15° C. However, this is not an official procedure.

Degluming is specified only for Bahia grass. The operation must

be done with care to avoid cracking the caryopsis in any way. A good

procedure is to place the seeds flat side down on a damp blotter or

cheesecloth, remove the outer thin, papery glume, insert the point of

the scalpel between the folded edges of the horny lemma and palea at

the pointed end of the seed, and carefully force the glumes open. The

naked caryopsis can then be carefully forced out. If there is reason

to believe thatthe seed may be dormant the caryopsis must be scratched

lightly on the end away from the embryo, and a 0.2-percent potassium

nitrate solution added to the substratum. All seeds considered "pure"

must be used, and if more than two or three "inert" seeds are found a

retest should be made on the pure seed separations.

The rules for seed testing provide for the testing of free caryopses

or burs of buffalo grass but do not indicate whether it is permissible

to remove the caryopses from burs as a part of the testing procedure.

Owing to the difficulty of obtaining germination of buffalo grass in the

bur, the rule has been interpreted as meaning that the caryopses may

be removed and tested as a part of the laboratory procedure. Extracting these is a slow and tedious process; it must be done with a sharp
130 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

scalpel, and the seeds from each bur kept separate. It has been found

practical to make individual sections with blotter strips on top of the

substratum in order to keep an accurate count of the germination of

seeds from each bur. A 0.2-percent potassium nitrate solution must

be added to the substratum.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Cereals and millets.—Folded towel tests are indicated for wheat,

barley, rye, oats, and rice. Indications are that rolled towel tests are

to be preferred in testing rice. In no case should more than 50 seeds

of any of the above-named kinds be placed on a folded towel approximately 51/2 by 7 inches in size. If upright rolled towels are used no

more than 50 seeds should be placed on an area 11 by 14 inches in

size. The usual amount of moisture should be maintained on these

tests, except for rice, which should be wetter than average, especially

during the initial stages of germination.

Soil or sand tests of rice should have more than the usual amount

of water added to them, although this is not specified in the rules.

The following procedure is used in one laboratory located in a riceproducing area : After the seeds have been placed on top of normally

moistened sand in pans 9 by 9 by 2 inches in size, add an additional

250 cc. of water. On the seventh day of test, at which time the seedlings have become anchored in the sand or soil, add enough water to

cover the seed approximately one-fourth inch. Only a final count

should be made.

Folded blotters are specified for rice, sorghum, Sudan grass, and

the millets. They are not desirable for rice, since they do not provide enough moisture, and are too small to accommodate even 50 rice

seeds without undue crowding. They do make a very nice substratum

for the millets, sorghum, and Sudan grass. No more than 50 seeds

of sorghum or 100 seeds of Sudan grass or millet should be tested

in blotters having 25 to 30 square inches of surface after folding.

After the seeds have absorbed water, the blotters should be kept

slightly dry, especially on tests of sorghums and Sudan grass.

Rolled towel tests are indicated for corn. Rolls placed in the upright position are preferred, and not more than 50 seeds should be

placed in towels 11 by 14 inches in size. Care should be taken not

to keep tests of corn too wet.

Soil or sand is indicated as an alternate substratum for wheat, barley, rye, oats, corn, sorghum, and Sudan grass. Waxed cardboard soil

boxes 414 by 41/^ by li/^ inches in size are satisfactory for all cereals

except corn, which should be germinated in boxes 814 by 8% by 1%

inches in size. In no case should more than 50 seeds of any one kind

be put in these containers, making eight replicates for a complete test

of 400 seeds.

Small-seeded grasses.—These are usually placed in covered Petri

dishes, although top-of-blotter tests are indicated as an alternate substratum for a few kinds. Top-of-blotter tests should not be used

if (1) a long test period is required and (2) potassium nitrate is

specified.

No more than 100 seeds should ever be placed in a 100- or 120-mm.

Petri dish or on top of a blotter 4% by 6 inches in size. Seeds as

large as Rescue grass should not be spaced any closer than 50 seeds in

a 100-mm, Petri dish.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 131

SEEDLING INTERPRETATION

The plumule in the grass family appears above the ground and the

first foliage leaf is enclosed in a white sheath or coleoptile, the pointed

tip of which is broken open as the leaves elongate. As the seedling

grows, permanent roots arise from the base of the first foliage leaf,

and other whorls of permanent roots arise from the nodes above. The

primary root system is temporary and soon dies.

Seedlings are not usually held in test long enough for analysts to

observe any development except that of the primary root system and

of the first foliage leaf and coleoptile. Since the grass cotyledon

serves as the food-absorbing organ, decay of any of its parts may

result in weakened and abnormal seedlings.

A perfect grass seedling should have a well-developed primary root

system, an intact cotyledon or scutellum, seed free from serious decay,

and long, well-developed green leaves within the coleoptile. One or

more leaves may have broken through the coleoptile by the end of

the test period. Seedlings should not be removed from test until they

have developed to a stage whereby the structure, color, and general

condition of the plumule and primarv root system can be observed.

(Figs. 35-43.)

Barley^ oats^ rye^ and wheat.—These four cereals exhibit practically

the same growth pattern, although the speed of germination varies

with the kinds. Preliminary counts on wheat, barley, or rye

should not be made before the fourth to fifth day of test, and on oats

before the fifth to sixth day. Since the roots emerge first, analysts

may be tempted to remove seedlings before the condition of the shoot

can be determined. One advantage of the sand or soil test on cereals

is that all seedlings can be left for one final evaluation, at which time

they have developed to a stage where their essential structures may

be easily seen. The soil test is particularly desirable as an aid in

evaluating frost-damaged oats and mechanically injured rye (figs.

35,36,37).

Seedlings of barley, oats, rye, and wheat are to be regarded as

normal if they have: (1) At least one primary or seminal root, but

preferably two or three seminal roots, provided the shoot is well

developed and the grain is not badly decayed; (2) well-developed

leaves, green in color, and long enough to extend more than half

way up into the sheath or coleoptile at the time the seedling is evaluated ; (3) spiral twisting or bending of the shoot, provided it is green

in color, has normal length, and is not frost damaged; and (4) slight

infection by fungi, provided none of the essential seedling structures

have been damaged.

Abnormal seedlings are those that have: (1) No primary root; (2)

only one or tivo short or spindly seminal roots which are usually accompanied by weakened shoots and decayed grains; (3) no green

leaves, but only the white sheath or coleoptile formed, which may or

may not be grainy, spirally twisted, split, or shortened; (4) a shortened shoot, extending no more than one-half the way up through the

coleoptile; (5) a thin, spindly, or watery shoot usually accompanied

by weak root development and decayed grains; (6) badly shattered

or longitudinally split leaves, with or without splitting of the coleoptile; (7) thickened and shortened shoot (leaves and coleoptile), often

the result of overtreatment of seed with chemicals; (8) decayed
132 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FiouEE 35.—Oats (Avena sativa). Normal and abnormal seedlings (exhibiting

frost injury) from 10-day tests in towels.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 133

FiQTJEE 36.—Rye (Sécale céréale). Normal seedlings from 7-clay tests in towels.
134 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FIGURE 37.—Eye {Sécale céréale). Abnormal seedlings from 7-day tests in

towels.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 135

FIGURE 38.—Kice (Oryxa sativa). Normal and abnormal seedlings from 14-day

tests iu towels.
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FIGURE 39.—Corn (Zea mays). Normal seedlings from 7-day tests in towels.
FIGURE 40.—Corn {Zea mays). Abnormal seedlings from 7-day tests in towels.

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FIGURE 41.—Sorghum (Sorglmm vulgäre). Normal seedlings from 10-ilay tests in blotters.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 139

FiGUKE 42.- -Sorghum {Sorghum vulgäre). Abnormal

tests In blotters.

see(Jlin};s from lO-day

slioots, provided the decay is not tlie result of improper test

conditions; the shoots usually appear weak and show decay near

the point of attachment to the grain which is usually rotten ; (9) badly

frost-damaged seedlings, characterized by grainy coleoptiles and

spirally twisted leaves and coleoptiles ; or coleoptile developed without

the leaves (in soil tests, some of the longest of the spirally twisted

seedlings will appear fairly strong but most of them break off just

above the attachment of the plumule and coleoptile to the grain; the

shortest of the seedlings do not emerge in soil tests) ; and (10) various

combinations of the above-named abnormal types.

Rice.—Preliminary counts on rice should not be made before at

least the fifth to seventh day of test, since the shoots are slower than

the roots to develop (fig. 38). Development of fungi on seeds and

seedlings may cause extreme variation in test residts. More luiiform

results will be obtained if samples are well spaced and grown in

"flooded" sand or soil or placed in upright rolled towel tests, as

explained on page 130.

Normal seedlings include those that have: (1) One primary root,

usually with numerous lateral roots; several permanent roots arising

from the first node should be present if seedlings are not removed

until the end of the test; (2) well-developed green leaves which ordinarily should have broken through the coleoptile at the time the seedling is evaluated; and (3) slight infection by fungi, provided none

of the essential seedling structures have been damaged.

Abnormal seedlings should be those that have: (1) No roots; (2)

a spindly primary root with very little or no branching or secondary

development; (3) no green leaves, but only the white sheath or coleoptile; (4) a spindly and sometimes watery shoot which is usually

associated with decay of the rice grain; (5) a short leaf, extending

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FioDEE 43.—Timothy (Phleum pratense). Normal and abnormal seedllngs from 10-day tests in Petrl dishes.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 141

no more than one-half the distance up through the coleoptile; (6)

shattered or longitudinally split plumules with or without splittmg

of the coleoptile; (7) decayed plumules, provided the decay is not

the result of improper test conditions (the plumules usually are weak

appearing and show decay near the point of attachment to the grain) ;

and (8) various combinations of the above-named abnormal types.

Corn.—Preliminary counts should usually be made on the fourth

day of test or samples may be left for a single count when soil or

sand tests are made. (Figs. 39, 40.)

Normal seedlings include those that have: (1) One primary root,

usually with secondary roots present; (2) no primary root, but with

at least two vigorous secondary roots, provided the grain is not badly

decayed, and the shoot is well developed; (3) well-developed green

leaves, usually broken through the coleoptile by the end of the test

period; (4) twisted and curled shoots bound by the tough seed coat,

provided the shoot is not decayed; and (5) slight infection by fungi,

provided none of the essential seedling structures have been damaged.

Abnormal seedlings include those that have: (1) No primary or

secondary roots; (2) no primary roots but small and weak secondary

roots; (3) no plumule, but only the white sheath or coleoptile; (4)

a shortened plumule, extending no more than one-half the way up

through the coleoptile; (5) a thickened and shortened shoot; often

the result of overtreatment of seed with chemicals; (6) a spindly and

pale shoot usually associated with moldy seeds; (7) albino (entirely

white) seedlings, which will not develop into plants because of lack

of chlorophyll; (8) shattered or longitudinally split leaves, with or

without splitting of the coleoptile; (9) decayed shoots, provided the

decay is not the result of improper test conditions (the plumules

usually appear weak and show decay near the point of attachment to

the grain and the scutellum is usually rotten) ; and (10) various combinations of the above-named abnormal types.

Sorghum and Sudan grass,—Preliminary counts should not be made

until the fourth or preferably the fifth day of test. It is desirable

that only a final count be made for soil and sand tests. (Figs. 41, 42.)

Development of fungi on seeds and seedlings may cause extreme variation in test results. More uniform results will be obtained if (1)

the seeds are widely spaced in blotter tests, (2) the substratum is kept

on the "dry" side, or (3) the seeds are tested in soil or sand.

Normal seedlings include those that have: (1) One primary root,

usually with well-developed secondary roots and root hairs if left

for final counts in soil tests; (2) well-developed, green leaves, usually

broken through the coleoptile by the end of the test period ; (3) slight

infection by fungi, provided none of the essential seedling structures

have been damaged; and (4) red coloration on the roots and on the

coleoptile of the shoot, caused by natural pigments, provided the seedling is otherwise normal.

Abnormal seedlings include those that have: (1) No roots; (2) a

weak, spindly, and usually shortened primary root, which is often

associated with decay of the grain ; (3) no plumule, but only the white

sheath or coleoptile ; (4) a shortened plumule, extending no more than

one-half the way up through the coleoptile; (5) a spindly and pale

{)lumule, usually associated with moldy seeds; (6) shattered and

ongitudinally split plumules, with or without splitting of the coleop-
142 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

tile; (7) decayed plumules, provided the decay is not the result of

improper test conditions (the plumules usually appear weak and show

decay near the point of attachment to the grain which is usually

rotten) ; and (8) various combinations of the above-named abnormal

types.

Grasses and millets.—It is frequently necessary to use a hand lens

for close observation of abnormal types on the small-seeded grasses

and millets. (Fig. 43.)

Normal seedlings include those that have: (1) A well-developed

primary root, usually with root hairs; (2) a well-developed green

plumule which has usually broken through the coleoptile by the end

of the test period; (3) slight infection by fungi, provided none of the

essential seedling structures have been damaged; (4) spirally coiled

roots held within the tightly enveloping glumes as in certain samples

of Bermuda grass; and (5) poor root development resulting from

injury caused by use of a potassium nitrate solution; however, if

many roots are affected, a retest should be made on top of soil in closed

Petri dishes.

Abnormal seedlings include those that have: (1) No root; (2) a

weak, stubby, or spindly root, usually short and watery, associated

with a decayed seed; (3) no plumule, but only the white sheath or

coleoptile which is often short and thick; (4) a shortened plumule,

extending only one-half the distance up through the coleoptile; (5)

a spindly plumule, usually pale and watery; (6) a shattered longitudinally split plumule with or without splitting of the coleoptile;

(7) decayed plumules, provided the decay is not the result of improper test conditions (the plumules usually appear weak and show

decay near the point of attachment to the seed, which is usually rotten) ; and (8) various combinations of the above-named abnormal

types.

LEGUMINOSAE (LEGUME OR PEA FAMILY)

KINDS OF SEED

Alfalfa—Medicago sativa.

Beans :

Adzuki—Phaseolus angularis.

Asparagus—Vigna sesquipedal^.

Garden or field—Phaseolus vulgaris.

Horse or broad—Vicia faha.

Lima—Phaseolus lunatus var. macrocarpns.

Mung—Phaseolus aureus.

Runner—Phaseolus coccineus.

Velvet—Stizolohimn deeringianum.

Beggarweed—Desmodiwm tortuo-sum.

Chickpea—Cicer arietinum.

Clovers :

Alsike—Trifolium hyhridum.

Alyce—Alysicarpus vaginalis.

Berseem—Trifolium alcxandrinum.

Bur—Medicago hismda.

Bur, spotted—Medicago arahica.

Cluster—Trifolium glomerattim.

Crimson—Trifolium incarnatum.

Ladino—Trifolium repens.

Lappa—Trifolium, lappaceum.

Large hop—Trifolium proGuml)ens,

Persian—Trifolium resupinatum.

Red—Trifolium. pratense. • 21 T ^„
TESTING AGRICULTURAL AND VEGETABLE SEEDS 143

Clovers—Continued.

Sour—Melilotus indica.

Strawberry—TrifoUum fragiferum.

Sub—TrifoUum suhterraneum.

Suckling (small hop)—TrifoUum dnhium.

Sweet—MeUlotus alha and M. oßcinaUs.

White—TrifoUum repens.

Cowpea—Vigna sinensis.

Crotalaria—Crotalaria intermedia, C. jwwca, (I JanveolaUi, C. spcctahiUs, and

G. striata (mucronata).

Kudzu—Pueraria thunbergiana.

Lespedeza :

Common and Kobe—Lespedeza striata.

Koreein—Lespedeza stipnlacea.

Sericea or Chinese—Lespedeza cunea la.

Siberian—Lespedeza Jiedgsaroides.

Lupine :

Blue—Lupinus angustifoUus.

White—Lupinus alhus.

Yellow—Lupinus luteus.

Medic, black—Medicago lupuUna.

Peanut—Arachis liypogaea.

Peas :

Field—Pisum satitmm var. arvensc.

Garden—Pisum sativum.

Rough pea—Lathyrus Mrsutus.

Sainfoin—Onohrychis viciaefolia.

Sesbania—Seshania exaltata.

Soybean (field and vegetable)—Glyoine max.

Trefoil :

Big—Lotus uUginosus.

Birdsfoot—Lotus corniculatus.

Vetch :

Common—Vicia sativa.

Hairy—Vicia viUosa.

Hungarian—Vicia pannonica.

Monantha—Vicia articulâta (V. monantha).

Narrowleaf—Vicia angustifoUa.

Purple—Vicia atropurpúrea.

Woollypod—Vicia dasycarpa.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Dormancy may be encountered in the laboratory testing of clovers,

horse or broad beans, and peanuts, but it is unlikely that it will occur

in any of the other legumes listed herein. Dormant legume seeds

may absorb water and swell but still fail to germinate. Temperature

is the important treatment in the above-mentioned kinds. Impermeable seed coats may occur in all the legumes except peanuts,

but scarification treatments to overcome this t^^pe of dormancy are

not included in the rules for seed testing.

Clovers,—Oi the clovers listed in the rules, all except Alyce clover

may exhibit primary dormancy or be thrown into secondary dormancy

if the germination temperature is too high. In no case should the

temperature ever exceed 20° C. and 17° to 18° C. is most desirable. If

dormancy is still encountered, the seeds should be placed at 15° C.

Conversely, high temperatures are necessary for the germination

of Alyce clover, although as the seed ages it becomes tolerant of lower

temperatures. ^ The rules specify 35° C. as the germination temperature and it is imperative that this temperature be maintained when

freshly harvested seed is tested, as dormancy may be present at lower

temperatures, even at 30°. At the end of the 20-day test period a
144 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

few swollen seeds are usually present. The swollen seeds should be

carefully pierced with a needle or scalpel (care being taken not to

injure the embryo) and then placed back in test for 5 additional days.

Broad 'bean.—Horse or broad bean should never be germinated at

temperatures above 20° C. and 17° to 18° C. is most desirable. If

dormancy is encountered, the seeds should be placed at 10° C. for

3 days and then moved to 20° C. for the duration of the test period.

Peamds.—There is no provision in the rules for the laboratory treatment of dormant peanuts. There are data to show that dormancy

does occur in peanuts, that the extent varies with the varieties, and

that moist storage at temperatures as high as 30° to 40° prior to

testing favor the germination of freshly harvested seed. A few tests

made in the Federal laboratory at Beltsville on dormant peanuts indicate that a constant temperature of 30° C. may be a satisfactory

laboratory treatment for overcoming this condition.

HARD SEEDS

In blotter tests, the percentage of hard seeds must be determined

for all kinds of legumes except peanuts. In soil and sand tests, it

is usually necessary to sieve the substratum in order to determine

the presence and number of hard seeds. If swollen seeds are present

they may be removed, placed in towel tests, and evaluated after 5 additional days, as provided in the rules. It is impractical to try to

recover hard seeds of the smaller legumes such as clovers from soil

and sand tests.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

The choice of substrata, particularly for the large-seeded legumes,

may cause confusion as to which to use. An artificial medium is

usually preferred in laboratories handling large volumes of work,

although it is impossible for an analyst properly to interpret the

results of the germination test without being familiar with the seedling development of the various kinds in soil or sand. The artificial

substrata listed for legumes are rolled towels, flat folded towels, folded

blotters, and creped cellulose paper wadding. Soil and sand are

listed as a choice of substratum on those kinds which may be

particularly troublesome to interpret.

Rolled towel tests,—More satisfactory results will be obtained if

rolled towel tests are placed in an upright or slanted position during

the germination period. The small horse beans can be successfully

germinated in upright rolled towels, although this is not indicated in

the rules. In the use of paper towels, cut to an approximate size of 11

by 14 inches, no more than the following number of seeds should be

placed in each roll : Mung beans, 100 ; field, garden, runner, adzuki,

asparagus, small horse beans, and small lima beans, 50; field peas,

garden peas, chickpeas, cowpeas, lupines (blue, white, yellow), peanuts, and soybeans (field and vegetable), 50 ; and large lima beans and

velvet beans, 25. A minimum of 400 seeds should be tested even

though this may require as many as 16 replicates per test.

Since the large-seeded legumes will absorb a great deal of moisture

during the first stages of germination, the towels should be saturated

with water at the time the tests are set up. After the seeds have absorbed water it will not be necessary for the towels to be so wet. In

fact, it is best that the towels be only moderately damp, having only
TESTING AGRICULTURAL AND VEGETABLE SEEDS 145

enough moisture to maintain seedling growth without excessive drying, in order to discourage decay and growth of fungi. Observation

of the moisture content of the rolls should be made regularly, preferably daily, and water added when needed.

Folded towel tests,—Flat, folded towels are listed for the following kinds of legumes : White and yellow lupines, kudzu, rough peas,

sesbania, vetches, and bur clovers. It is entirely possible that upright

rolled tests could be used successfully on kudzu, rough peas, sesbania

and vetches. Because of the spherical shape and small size of most

of these kinds, it would be necessary to guard against the loss of seeds

by rolling and the accumulation of excess moisture in the rolls. Advantages observed on common vetch include faster germination and

easier interpretation.

Paper towels, 11 by 14 inches, folded to 5^ by 7 inches in size are

very satisfactory for the folded towel tests. The following numbers

of seeds should be placed in each towel : Sesbania and bur clovers,

100; kudzu, rough pea, and vetches, 50. If white or yellow lupines

are germinated in flat towels, they should be placed not more than 50

seeds to an area approximately 11 by 14 inches.

In addition to the first and final count on kudzu, rough peas,

vetches, and bur clovers, one or two intermediate counts, spaced 2 or

3 days apart, should be made. At the time of the preliminary counts

all decayed seeds should be removed and recorded.

Folded Hotters,—Folded blotters are listed for the following kinds

of legumes : Beggarweed ; crotalarias ; lespedezas ; sainfoin ; alfalfa ;

clovers ; black medic ; and trefoil. Both flat-folded towels and blotters are listed for bur clover because the seed is sometimes received

in the seed pod, in which case a towel will afford more space for the

seeds and will also supply more initial moisture. The following numbers of seeds should be placed in each blotter folded to size 4% by 6

inches: Beggarweed, lespedeza, alfalfa, clovers, black medic, and

trefoil, 100 ; and crotalaria, 50 or 25, depending on the size of the seed

and the amount of mechanical breakage. Sixteen replicates of 25 seeds

each are necessary for proper spacing of some samples of crotalaria.

It will be necessary to make more than a first and final count on

tests of more than 7 days' duration. Counts at 2- or 3-day intervals

during the test period are usually satisfactory, although such samples

as scarified crotalarias should be checked daily after the first count.

Greped cellulose paper wadding,—An alternate substratum for the

large horse or broad beans, lima beans, and velvet beans is creped

cellulose paper wadding (0.3-inch thick) covered with a single thickness of blotter through which holes are punched for the seeds which

are pressed for about l^ their length into the creped paper wadding.

In no case should more than the following number of seeds be placed

on an area approximately 9 by 9i/^ inches in size: Small lima and

horse beans^ 50; and large lima beans, large horse beans, and velvet

beans, 25. Four hundred seeds of each kind must be tested, even

though 16 replicates are necessary. Since the spread of fungi is very

rapid in creped cellulose wadding, the tests should be examined daily

for the presence of decayed seeds, which should be removed and recorded. Preliminary counts can be made or the seedlings may be left

in test for the final count only.

Soil and sand,—A combination of soil and sand is listed as an alter-
146 AGRICULTURE HANDBOOK KO. 30, U. S. DEPT. OF AGRICULTURE

nate substratum for many kinds of legumes and may also be used in

making check tests on any of the kinds in case problems of interpretation arise.

The number of seeds to be placed in each container for test will depend on the size of the seeds and of the containers. The kinds and

number of seeds to be placed in large containers (8I/2 by 81/^ by 1%

inches) are as follows : Large lima beans, adzuki beans, runner beans,

asparagus beans, small lima beans, broad beans, chickpeas, cowpeas,

blue lupines, peanuts, and field and garden peas, 50; and mung beans,

100. The following kinds and numbers should be placed in small containers (43/2 by 41/2 by li/^ inches) for test: Crotalaria, 50 or 25 (depending on size and condition of the seed) ; lespedeza, 100; common

vetch, 50; and alfalfa, alsike, berseem clover, crimson clover, ladino

clover, red clover, sweetclover, white clover, and black medic, 100.

SEEDLING INTERPRETATION

It is recommended that only the final count be made on all soil and

sand tests because it is possible to make a moi'e accurate seedling evaluation wlien a com])arison is made between the strong and weak seedlings. (Figs. 44-56.)

Legume seedlings may exhibit either hypogeous or epigeous growth.

In epigeous development as in lima beans, and garden beans, the only

underground part of tlie seedling is the root and the lower part of the

hypocotyl. The latter lengthens and appears above the ground carrying the two cotyledons with it. The growth above the cotyledons

^

FIGURE 44.—Bean (PUaseolus vulyaris). Six seedlings, illusti-ating from left

to right, one decayed, three "other abnormal," one "baldhead," and one normal ;

from 8-day tests in soil.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 147

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FIGURE 46.—Lima bean (Fhascolus lunatus var. maorocarpus). Abnormal seedlings from 9-day tests in sand.
148 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

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FIGURE 47.—Lima bean (Phaseolus lunatus var. macrocarpus). "Baldheads,"

or abnormal seedlings from 9-day tests in sand.

FiGintE 48.—Field peas {Pisum sativum var. arvense). Normal seedlings from

8-day tests in soil.
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TESTING AGRICULTURAL AND VEGETABLE SEEDS 153

FIGURE 53.- -Alfalfa {Medicago sativa). Normal and abnormal seedlings from

7-day tests between blotters.

forms the epicotj'l consisting of a stem with terminal bnd and two

primary leaves. In hypogeons development as in peas, the underground parts of the seedling are tlie root, the very shortened hypocotyl, and the two cotyledons. The epicotyl elongates above the

cotyledons and emerges from the ground forming the stem and leaves.

Beans—garden, field, lima, adzuki, niung, and asparagus.—Seedling interpretation for adzuki, mung, and asparagus beans may be

considered as being similar to that discussed for garden, field, and

lima beans for they all have the same type of epigeous development.

(Figs. 44-47.)

If preliminary counts are made before the cotyledons have opened,

the analyst must part them manually in order to determine the condition of the primary leaves and the terminal bud. By the end of the

germination test, a perfectly normal seedling should have a wellformed root, Avith or without secondary or adventitious development ;

a strong, fairly long stem or hypocotyl with two attached cotyledons,

and two well-developed first or primary leaves and an intact terminal

bud. Injury to the epicotyl is very common on garden, field, and lima

beans. Considerable research on the growth and development of these

kinds has resulted in a more or less standardized classification of seedlings into normal and abnormal groups for seed-testing purposes.

Types of bean seedlings to be regarded as normal are discussed as

follows :

1. The seedling must have two primary leaves, or at least one

primary leaf, even though one or both cotyledons are absent. The

terminal bud must be present in either case.
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FiGUKE 55.- -Birdsfoot trefoil (Lotus corniculatus). Normal and abnormal seedlings from 7-day tests

in blotters.

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156 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FIGURE 56.—Crotalaria (Crotalaria speotaiilis). Normal and abnormal seedlings from 8-day tests in blotters.

2. The seedling must have a primary root or a set of adventitious

or secondary roots suiRcient to anchor it when grown in soil or sand,

provided the hypocotyl is not badly shortened.

3. The normal seedling must have a fairly well-developed hypocotyl

with no prominent breaks or deep lesions. Healed breaks, sometimes

referred to as "knees," are to be considered as normal, provided the

seedling is not spindly.

4. Normal seedlings may include those with slight infection from

fungi, pi'ovided the essential structures liave not been seriously damaged and appear to be able to carry on their normal functions at the

time of evaluation. If a few seedlings with total or partial decay

of the plumule are found, they may be counted as normal, ¡provided

the hypocotyl and root are well developed. The plumules on such

seedlings usually do not decay when grown under greenhouse conditions where the cotyledons open up naturally and are exposed to a dry

environment and sunlight. However, if there are many seedlings

with decayed plumules in a test, a retest should be made and such

seedlings evaluated cautiously.

5. Spirally twisted and curled root and hypocotyl held within the

tough seed coat, causing delayed development; otherwise normal.

At the present time, due to lack of data, analysts may count such seedlings as normal, provided the essential parts are present.

Abnormal bean seedlings include those that have: (1) No primary

leaves or terminal bud (baldheads) ; (2) no primary leaves, but with
TESTING AGRICULTURAL AND VEGETABLE SEEDS 157

a terminal bud (snakeheads or partial baldheads) ; (3) no primary

leaves, but terminal bud present and axillary buds in one or botli^ of

the cotyledons (partial baldheads) ; (4) a malformed hypocotyl, which

may be characterized by open splits, or appear curled, shortened, or

thickened; (5) no primary root or well-developed set of adventitious

or secondary roots; and (6) various combinations of the above-named

abnormal types.

Some seeds in badly broken samples w^ill be so injured that growth

will not occur beyond enlargement of the primary leaves within the

swollen cotyledons and the formation of vestiges of root and hypocotyl. Since these do not emerge in a soil test, such growths are referred to as "seeds too broken to grow" or as "splits."

Velvet hean^ hroad hean^ runner hean^ chickpea^ 'field fea^ garden

pea^ rough pea^ and vetches.—Because of their hypogeous seedling

development it will not be necessary to open the cotyledons to observe

the condition of the plumule if preliminary counts are made. However, seedlings should not be removed until the epicotyl has broken

through the seed coat and erected itself sufficiently so the analyst may

discern whether the epicotyl is intact. (Figs. 48, 49.)

By the end of the germination test a perfectly normal seedling

should have: (1) A well-formed root, with or without secondary or

adventitious development; (2) a strong epicotyl with fairly long stem ;

(3) a well-developed epicotyl with the leaves and terminal bud intact;

and (4) the seedling should not be broken away from the cotyledons.

Normal seedlings include those that have: (1) A primary root or

a set of secondary or adventitious roots sufficient to anchor the seedlings when grown in soil or sand, provided the stem is not badly

shortened ; (2) a fairly well-developed stem with no prominent breaks

or deep lesions which might interfere with the conducting tissues;

(3) a terminal bud with at least one first leaf and an intact growing

point; (4) two shoots, provided the seedling appears vigorous and

at least one of the shoots has a normal epicotyl and root; and (5)

slight infection by fungi, provided the essential seedling parts have

not been seriously damaged and appear to be able to carry on their

normal functions at the time of evaluation.

Abnormal seedlings include those that have: (1) No primary root

or well-developed secondary or adventitious roots; (2) a malformed

stem, which may be characterized by severe open splits, and

curled, shortened, or thickened development; (3) no epicotyl, or an

epicotyl without the terminal bud; (4) two shoots, both of which

appear weak and spindly, often partially broken away from the

cotyledons; (5) decayed seedlings caused by the spread of decay from

the cotyledons of the developing seedling; and (6) various combinations of the above-named abnormal types.

Severe mechanical breakage of certain kinds of seeds such as field

and garden peas and vetches may result in the development of mere

vestiges of seedlings. The embryonic plant may be almost broken

away from the cotyledons resulting in only slight development of the

different organs. Since such growths do not emerge in soil tests, the

seeds are regarded as "too broken to grow."

Severe weevil infestation is frequently found in field peas, which

often prevents development except for mere vestiges of seedlings.

Sometimes the cotyledons have been devoured to the extent that no
158 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

food supply is left for the developing seedling. Such insect injury

can be easily detected by examination of the cotyledons.

Cowpeas^ lupines^ peanuts^ and soybeans.—Because of the epigeous

seedling development, the cotyledons in this group must be parted

manually in order to determine the condition of the primary leaves,

and the growing point, if counts are made before the cotyledons have

opened. This is very necessary on lupines and peanuts, since mechanical breakage appears to interfere with the leaf development on these

more than it does on soybeans and cowpeas where the injury appears

to be confined to the hypocotyl and roots rather than to the epicotyl.

However, weevil damage to cowpeas may cause serious injury to the

epicotyl. It might not be practical to open manually the cotyledons

of all samples of soybeans on the preliminary counts, since epicotyl

injury is not too common ; but a few should be opened in each sample

and if there is evidence of mechanical injury it may be necessary to

open the cotyledons of all seedlings in that sample. If only a final

count is made the epicotyl will usually have emerged from between

the cotyledons, and the condition of the first leaves can be easily determined. Preliminary counts should be made on samples which show

mold or bacteria that might spread to healthy seedlings. At this

time, a normal seedling should have: (1) A well-formed root with

or without secondary or adventitious roots; (2) a strong and fairly

long hypocotyl with two attached, open cotyledons; (3) two welldeveloped first or primary leaves; and (4) an intact terminal bud

(figs. 50, 51, 52).

Normal seedlings include those that have: (1) A primary root or

a set of secondary or adventitious roots sufficient to anchor the seedlings when grown in soil or sand, provided the hypocotyl is normal ;

(2) a fairly well-developed hypocotyl with no prominent breaks or

deep lesions which might interfere with the conducting tissues; (3)

a plumule with at least one leaf and an intact growing point; and

(4) slight infection by fungi, provided the essential seedling parts

have not been seriously damaged and appear to be able to carry on

their normal functions at the time of evaluation.

Abnormal seedlings include those that have: (1) No primary root

or no well-developed secondary or adventitious roots ; (2) a malformed

hypocotyl which may be curled, shortened, or thickened or have severe

open splits; (3) no epicotyl, or one without the growing point, with

or without leaves; (4) decayed epicotyl, provided the decay has spread

from the rotted cotyledons of the developing seedling; and (5) various combinations of the above-named abnormal types.

Caution must be taken to insure that the decay is not caused by

improper test conditions. Tests made in the relatively dry atmosphere

and sunlight of a greenhouse are the best measure of the value of

samples having many decayed plumules.

As with beans, mechanical breakage of the seeds mav result in only

vestiges of seedlings, usually an enlarged plumule within the swollen

cotyledons and little or no development of the hypocotyl and radicle.

Since such growths do not emerge in soil tests, the seeds are regarded

as "too broken to grow."' Seeds of cowpeas, lupines, peanuts, and

soybeans may exhibit this condition.

Severe weevil infestation is found only in cowpeas, and will often

reduce development to only vestiges of seedlings. The embryonic
TESTING AGRICULTURAL AND VEGETABLE SEEDS 159

plant may be entirely or partially destroyed, or the cotyledons may

have been so badly devoured that there is no food supply left for the

developing seedling. Insect injury can be easily detected by examination of the cotyledons.

Glovers^ alfalfa^ Uaeh medic^ trefoil^ crotalarias^ les^edeza^ hudzu,

seshania^ leggarweed^ sainfoin.—Since these relatively small-seeded

legumes all have epigeous seedling development, the development of

the epicotyl cannot be discerned until the cotyledons have opened up

sufficiently for its emergence. (Figs. 53-56.) Breaks at the point

of attachment of the cotyledons to the hypocotyl, with injury to the

epicotyl, are very common in seeds which have been mechanically

damaged. Therefore, when preliminary counts are made on such

kinds, it is very important that seedlings should not be removed until

the condition of the cotyledons can be determined. It will not be practical to observe the epicotyl development except on badly broken

samples, or when samples are tested in soil, where the cotyledons will

open up naturally and the growing point of the epicotyl becomes

clearly visible. By the fourth or fifth day of the test the cotyledons of

most of the kinds listed herein will have developed to a stage where the

breaks can be seen. If the point of attachment of the cotyledons to

the hypocotyl cannot be seen at this time, the seed coat may be peeled

back far enough to determine whether a break has occurred. A hand

lens is usually necessary for the close observations required.

The advantages of sand or soil tests on these kinds of seeds are that

the cotyledons open up naturally by the end of the test period, injury

to the seedling is clearly visible, badly broken seedlings do not emerge,

and the analyst has the advantage of being able to judge the abnormal

types by direct comparison with the normals. The seeds most subject

to mechanical breakage are : Alfalfa ; most of the clovers ; black medic ;

trefoil; sericea lespedeza ; and the crotalarias.

By the end of the germination test a perfectly normal seedling

should have a long, slender root, usually with root hairs, a long hypocotyl, two attached cotyledons which have opened, and an intact epicotyl or growing point.

Normal seedlings include those that have: (1) A long, slender root,

usually with root hairs; (2) slightly stubby roots on blotter tests of

sweetclovers, provided the seedling is otherwise normal; (3) roots

slightly stubby from being held back by the attached seed coat, provided the seedling is otherwise normal; (4) short splits on the roots,

provided the split does not extend into the central conducting tissues

of the hypocotyl, and provided further that root hairs are present and

the seedling is normal in other respects; (5) a long, well-developed

hypocotyl which may have slight cracks or breaks, provided they do

not extend into the conducting tissues; (6) at least one cotyledon,

provided the epicotyl is also present; and (7) slight infection by fungi,

provided none of the essential seedling structures have been damaged.

Abnormal seedlings include those that have: (1) Stubby roots,

usually associated with shortened hypocotyls; (2) longitudinal,

deep splits on the roots, extending into the conducting tissues of the

hypocotyls; (3) deep cracks or breaks in the hypocotyl which extend

into the conducting tissues; (4) both cotyledons broken off; (5) one

cotyledon broken off if the epicotyl is also absent; (6) rotted cotyledons, provided the decay did not spread to the seedling from an adja-
160 AGRICULTURE HANDBOOK NO. 30, U. Ô. DEPT. OF AGRICULTURE

cent seed or was not the result of improper test conditions ; (7) spindly,

watery seedlings, provided they are not the result of excess moisture in

the substrata (usually seedlings of this type have one or more abnormalities of the essential structures, such as broken cotyledons or deep

splits in the hypocotyls) ; and (8) various combinations of the abovenamed types of abnormal seedlings.

Mechanical breakage of the seed may result in only vestiges of

seedlings, manifested by swollen cotyledons and broken, slightly enlarged hypocotyls or radicles. These seeds are regarded as "too

broken to grow^,'' since the resultant growths do not emerge in soil

tests. Insect damage may also cause lack of seedling grow^th.

LILIACEAE (LILY FAMILY)

KINDS OF SEED

Asparagus—Asparagus ofßoinalis.

Leek—Alliurn porrum.

Onion—Allium cepa.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Onion, leek, and asparagus apparently present no dormancy problems in routine laboratory testing. Asparagus frequently is slow to

germinate, the seeds imbibing water but not growing. Borthwick (7) found that freshly harvested and year-old asparagus seeds

germinated promptly when held at a constant temperature within the

range of 25° to 30° C. for the duration of the test period.

HARD SEEDS

Although it is permissible to report hard seeds in asparagus, there

is question whether the seeds remaining at the end of the germination

test are really hard. According to the definition, "hard seeds" are

those which have not absorbed water because of an impermeable seed

coat. Asparas'us seeds do absorb water during the course of the

test period. The failure of the seeds to germinate is not due to a

seed coat that is impermeable to water, but to some other cause.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Onion and leek are tested between blotters and asparagus between

folded towels. Not more than 100 seeds of onion and leek should be

placed in a blotter folded to 4% by 6 inches in size and no more than

50 seeds of asparagus in a towel folded to 5i/^ by 7 inches in size.

Upright rolled towels have proved to be very satisfactory for asparagus. No more than 100 seeds should be placed in a roll 11 by 14 inches

in size. Soil or sand is listed in the rules as an alternate substratum

for onions. No more than 100 seeds should be placed in a small container 414 by 41/2 by IY2 inches in size. It is recommended that only

one final count be made. Soil or sand tests must be continued for 12

days, Avhereas blotter tests should be discontinued at the end of 10

days.

SEEDLING INTERPRETATION

Onion and leek.—Onion and leek exhibit epigeous growth, the root

emerging first, and the cotyledon appearing above the surface of the

ground as a closed loop, its tip still adhering to the seed coat and

endosperm (fig. 57). As the seedling grows, the tip of the cotyledon
TESTING AGRICULTURAL AND VEGETABLE SEEDS 161

FIGURE 57.—Onion (Allium cepa). Normal and abnormal seedlings from 10-day

tests in blotters.

shrivels and becomes separated from the seed coat and the first foliage

leaf appears through a slit or pore in the cotyledon. Since the foliage

leaf does not develop during the laboratory test period, the analyst

will be able to observe only the leaflike cotyledon. By the end of the

test period a perfectly normal onion or leek seedling should have a

long, slender root with a thickened area where it is joined to the base

of the hypocoty], a fairly long hypocotyl, and a long, green cotyledon

with a definite loop or bend, often referred to as the "knee."

Normal seedlings include those that have: (1) A well-developed,

long, slender root, with or without root hairs; (2) a fairly long hypocotyl ; (?') a long, green, leaflike cotyledon, with a well-developed

bend or "knee"; and (4) slight infection by fungi, provided none of

the essential seedling structures have been damaged.

Abnornuil seedlings include those that have: (1) A thickened area

at the base of the hypocotyl with no root, or a stubby root; (2) a very

short hypocotyl, usually associated with a poorly developed root and

cotyledon ; (3) a poorly developed leaflike cotyledon without a definite

bend or '"knee"; (4) s])indly, watery seedlings, often slow in sprouting, and with one or more other abnornuilities ; (5) a rotted cotyledon,

provided the decay is not the result of iuiproper test conditions; and

(6) various combinations of the above-named abnormal types.

Asparagus.—Asparagus exhibits hypogeous growth, the cotyledon

remaining below the surface of the ground. After the seed has absorbed water the embryo enlarges and the immature seedling appears

as a swollen protuberance on one side of the seed. The root forms first

and then the stemlike epicotyl.
162 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

By the end of the test period a normal asparagus seedling should

have a long, slender root, a fairly long epicotyl, an intact terminal

bud, and the seedling should not be broken away from the cotyledon.

Itis necessary to allow the seedlings to develop to a stage whereby the

epicotyl development may be observed.

Normal seedlings include those that have : (1) A long, slender root;

(2) a long, well-developed epicotyl with terminal growing point; (3)

the cotyledon attached to the seedling; and (4) slight infection by

fungi, provided none of the essential seedling structures have been

damaged.

Abnormal seedlings include those that have : (1) No root, or a very

stubby root with weak secondary root development; (2) a malformed

epicotyl, which may be thickened, shortened, or twisted; (3) no terminal growing point or bud; (4) cotyledon broken away from the

seedling; (5) decayed epicotyl, provided the decay is not the result of

improper test conditions; and (6) various combinations of the abovenamed abnormal types.

LINACEAE (FLAX FAMILY)

KIND OF SEED

Flax—Linum usitatissimum.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Certain samples of flaxseed are retarded in germination at temperatures over 35° C. but germinate satisfactorily at alternating temperatures of 20°-30° C. as prescribed in the rules. However, flax is tested

at 20° in the Canadian laboratories and it has been suggested that

15° is necessary for germination of certain samples in the region of

Calgary, Canada.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

The standard procedure is to test flaxseed between blotters, but

soil and sand are alternate substrata. No more than 50 seeds should

be placed between blotters 4% by 6 inches in size, or in soil or sand

containers 41/2 by 4% by li/^ inches in size. Soil or sand tests will

aid in the interpretation of seedlings of samples which have been

mechanicall}' injured or subjected to severe chemical treatment.

SEEDLING INTERPRETATION

By the end of the germination test a normal flax seedling should

have a well-developed primary root, a long hypocotyl, two intact

cotyledons, and a small epicotyl which does not develop sufficiently

during the course of the laboratory test to be examined unless the

seedlings are left for final evaluation and the cotyledons manually

parted. It will not be necessary to do this except when badly broken

samples are being tested. (Fig. 58.)

Normal seedlings include those that have: (1) A long, slender root,

usually with root hairs; (2) a short or stubby primary root, provided

secondary root development is strong and the hypocotyl is of normal

length or approximately so; (3) a long, well-developed hypocotyl

with no breaks or lesions extending into the conducting tissues; (4)

at least one attached cotyledon, provided the epicotyl is not injured :

(5) variously broken or cracked cotyledons, provided the other seed-
FiouiîE 58.—Flax (Liiium tisitatissimum). Seedlings from 7-day tests In blotters.

Normal seedlings ; (right) abnormal seedlings.

(Left)

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164 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

ling parts appear normal; and (6) slight infection by fungi, provided

none of the essential seedling structures have been damaged.

Abnormal seedlings include those that have: (1) A stubby or no

primary root, provided the secondary root development is weak, a

condition usually associated with a shortened hypocotyl; (2) a malformed hypocotyl, which may be twisted, thickened, or shortened;

(3) deep cracks or lesions on the hypocotyl, extending into the conducting tissues; (4) both cotyledons broken off; (5) one cotyledon

broken off if the epicotyl is also injured; (6) decayed cotyledons or

other essential seedling structures, provided the decay is not the result

of improper test conditions; and (7) various combinations of the

above-named abnormal types.

MALVACEAE (MALLOW FAMILY)

KINDS OF SEED

Cotton—Gossypium spp.

Okra—HiTjiscus esculentus.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Impermeable seed coats may occur in okra or cotton but scarification treatments to overcome this type of dormancy are not accepted

as routine methods in seed testing.

HARD SEEDS

Although not indicated in the rules, hard seeds may occur in cotton.

The same treatment as provided in the rules for legumes, okra, and

asparagus should be applied to swollen and hard seeds of cotton.

It will be necessary to examine the soil or sand for the presence of

hard seeds at the end of the test period. If swollen seeds are present

they should be removed, placed in towel tests, and evaluated after 5

additional days.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Rolled towels are specified in the rules for cotton and okra. More

satisfactory results will be obtained if the tests are placed in an upright or slanted position during the germination period. When using

paper towels cut to approximately 11 by 14 inches in size, no more

than 50 seeds of each kind should be placed in a roll. It has been

found advantageous to stagger the rows of cotton in each roll so that

the germinating seedlings will have a minimum of contact with each

other. Because of the fungi carried on the fuzzy seed coats, proper

spacing of cottonseed is essential if uniform results are to be expected.

Soil and sand are also listed as substrata for cotton. Soil containers

approximately 8% by 8% by 1% inches are very satisfactory and only

50 seeds should be placed in each.

In addition to the rolled towels and soil or sand the following alternate method is specified for cotton : Shake the seed in a closed container, thoroughly wetting the lint and then blot off the excess

moisture. This method will be necessary only on certain "sensitive"

samples, which are those exhibiting slow growth and having numerous fungi on the fuzzy seed coats.

Owing to the absorption of the added moisture by the lint on the

seeds, faster germination is obtained by the "prewet" method, and

the seedlings emerge before the fungi have a chance to develop. It
TESTING AGRICULTURAL AND VEGETABLE SEEDS 165

ajjpears possible that approximately the same results could be obtained

by keeping upright rolled tests of cottonseed quite wet for the first

few days of test.

SEEDLING INTERPRETATION

By the end of the germination test a perfectly normal seedling

should have a long, well-developed root with root hairs, a long hypocotyl, and two attached green leaflike cotyledons, with a tiny epicotyl

formed between them. It will not be possible or practical to observe

the epicotyl development on any except those tested in soil or on those

abnormal seedlings which are left in test for final interpretation at

the end of the test period in artificial substrata. (Figs. 59, GO.)

FIGURE 59.- -Cotton {Oossypium spp.). Normal and abnormal seedlings from

12-day tests in towels.
166 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

FIGURE 60.—Okra {Uniscus esculentus). Normal and abnormal seedlings from

21-day tests in towels.

Normal seedlings include those that have: (1) A well-developed,

long, slender root, usually with root hairs; (2) no primary root but

strong secondary roots, provided the hypocotyl is of normal or approximately normal length ; (3) a long, well-developed hypocotyl with

no breaks or deep grainy lesions which might interfere with the con-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 167

ducting tissues; (4) at least one cotyledon and intact epicotyl; (5)

slight infection by fungi, provided none of the essential seedling

structures have been damaged; and (6) yellowish hypocotyls or roots

of cotton which may appear diseased, provided the cotyledons are

free of infection (the seed coat must be peeled back on young seedlings

to determine this condition of the cotyledons).

Abnormal seedlings include those that have: (1) No root or very

stubby roots, usually associated with a shortened hypocotyl; (2)

stubby roots and thickened hypocotyls resulting from chemical treatment of seed, such as often occurs on delinted cottonseed; (3) malformed hypocotyl, which may be curled, thickened, or shortened; (4)

deep cracks or grainy lesions on the hypocotyl which appear to interfere with the conducting tissues ; (5) epicotyl absent, even though one

or both cotyledons are attached; (6) decayed cotyledons and hypocotyls, provided the decay did not spread from another seed or was

not the result of improper test conditions; and (7) various combinations of the above-named abnormal types.

POLYGONACEAE (KNOTWEED FAMILY), SOLANACEAE (NIGHTSHADE

FAMILY), UMBELLIFERAE (CARROT FAMILY), AND MISCELLANEOUS

KINDS IN OTHER FAMILIES

KINDS OF SEED

Knotweed family :

Buckwheat—Fagopyrum esculentum.

Sorrel—Rumeœ acetosa.

Rhubarb—Rheuwi rhaponticum.

Nightshade family :

Eggplant—Solamim melongena var. esculentum.

Pepper—Capsicum spp.

Tomato—Lycopersicon esculentum.

Husk tomato—Physalis ptihescens.

Carrot family :

Carrot—Daucus carota.

Celery—Apiunv graveolens var. dulce.

Celeriac—Apium graveolens var. rapaceum.

Parsley—Petroselinum hortense.

Parsnip—Pastinaca sativa.

Valerian family :

Cornsalad (Fetticus)—Valerianella locusta var. oUtoria.

Hemp family :

Hemp—Gannahis sativa.

Geranium family :

Alfilaria—Erodium cicutarium.

OCCURRENCE AND LABORATORY TREATMENTS FOR OVERCOMING DORMANCY

Umhelliferae,—Dormancy may occur in seeds of any of the kinds

of Umhelliferae (carrot family) listed above. However, dormancy

should not be confused with low germination owing to the presence of

embryoless seeds, which can be determined by dissection of the seeds.

Light is specified for the germination of celery and celeriac; potassium nitrate and prechilling are indicated for dormant samples of

these kinds. There are no provisions in the rules for treatment of

dormancy in carrot, parsnip, or parsley, although there are certain

indications that occasional samples may be dormant. Treatment of

parsnip seed Avith potassium nitrate and exposure of parsnip and
168 AGRICULTURE HANDBOOK NO. 3Ô, Ü. Ô. DEPT. OF AORICULTURE

parsley seeds to lower constant temperatures, or lower alternations of

temperature than those specified in the rules have been suggested as

methods of overcoming dormancy.

Solanaceae.—Tomato and husk tomato may exhibit dormancy but

dormant samples of pepper and eggplant are rarely, if ever, found.

The only treatment specified in the rules for husk tomato is light, although Heit {28) has recommended moistening the substratum with

potassium nitrate for Physalis spp. The provisions in the rules for

overcoming dormancy in tomato are probably adequate ; however, an

alternating low-high temperature has also been found beneficial

(Shuck {Jß)), The rules specify that dormant samples of tomato

shall be exposed to light and the substratum moistened with a potassium nitrate solution.

Polygonaceae.—Apparently buckwheat seed does not exhibit

dormancy, but rhubarb may. The rules provide that rhubarb seed

shall be tested on top of soil at an alternating temperature of 20°-30°

C, with light. According to Heit {27) light is beneficial to some

samples and germination is satisfactory on top of blotters. The

control of fungi is of major importance in the testing of rhubarb

seed. Eesults may be more uniform when such seed stocks are tested

on top of soil rather than on top of blotters. The rules provide that

sorrel shall be tested on top of soil or in Petri dishes at an alternating

temperature of 20°-30° C, with light. Dormant seed should be

placed at 15° C. Some samples may require moistening of the substratum with a potassium nitrate solution.

Valerianaceae.—The provision in the rules to place dormant

samples of cornsalad at a low temperature for test appears to be

adequate.

Cannabinaceae.—^Apparently dormancy in hemp seed is not encountered in laboratory testing.

Geraniaceae.—Alfilaria is usually dormant. Clipping the ends of

the seeds (fruits) as provided in the rules is apparently an adequate

treatment for overcoming this condition. Care must be taken to clip

the fruit on the end opposite the embryo to avoid injuring it.

SUBSTRATA, SPACING, AND SPECIAL TREATMENTS

Celery, celeriac, husk tomato, and sorrel may be tested in Petri

dishes. Petri dishes are not listed in the rules for tomato, although it

is almost necessary to use them when dormant samples must have

light. Not more than 100 seeds of any of the kinds listed above

should be placed in a 100- or 120-mm. Petri dish.

Pepper and eggplant may be tested on top of blotters as a regular

method, and celery, celeriac, and husk tomato as an alternate method.

No more than 100 seeds of any of these kinds should be placed on top

of a blotter 4% by 6 inches in size.

Buckwheat, carrot, parsnip, parsley, tomato, cornsalad, hemp, and

alfilaria are regularly tested between blotters. Not more than 50

seeds of buckwheat and hemp, and not more than 100 seeds of carrot,

parsnip, parsley, tomato, cornsalad, or alfilaria should be placed betw^een a folded blotter 4% by 6 inches in size. Buckwheat may

also be tested between folded towels as an alternate substratum. Not

more than 50 seeds should be placed in a towel 5% by 7 inches in size.

Soil is the only substratum listed in the rules for rhubarb and it
TESTING AGRICULTURAL AND VEGETABLE SEEDS 169

is also an alternate substratum for sorrel. Rhubarb should be phiced

on top of soil in small open containers. The seeds should be pressed

for about one-half their length into the top of soil, 25 seeds placed in

boxes 4y2 by 4^2 by ly^ inches in size. This necessitates 16 replicates

for a complete test. Sorrel may be placed on top of soil in a closed

Petri dish, not more than 100 seeds being placed in a dish 100- or 120-

mm. in size.

Pepi^er, eggplant, and tomato may be tested between blotters with

raised covers as an alternate substratum. Not more than 100 seeds

of any of these kinds should be placed in a blotter 4% by 6 inches in

size.

SEEDLING INTERPRETATION

The only true seeds in this group are pepper, tomato, husk tomato,

and eggplant, all of which are members of the nightshade family.

The rest are fruits or half fruits, each containing a single seed. The

fruits in the Umbelliferae normally occur in two's, splitting longitudinally down the center, forming two single-seeded half fruits when

mature. Samples received for test may be half fruits, each containing a single seed, or they may be whole fruits containing two seeds.

Only single seeds (fruits) of the carrot family should be placed for

test; however, if double seeds are germinated only one seeclling from

each is to be counted. (Fig. 61, 62.)

NORMAL

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TESTING AGRICULTURAL AND VEGETABLE SEEDS 171

Normal seedlings include those that have: (1) A well-developed

primary root, usually with root hairs ; (2) a stubby root or no primary

root, provided the secondary root development is strong and the hypocotyl is near normal length as is frequently encountered in tomato

seedlings; (3) a long, well-formed hypocotyl, with no prominent

breaks or lesions extending into the conducting tissues; (4) at least

one attached cotyledon, provided the epicotyl is intact and the seedling

is otherwise normal (a tiny epicotyl may be observed in seedlings left

in test for final evaluation) ; and (5) slight infection by fungi, provided none of the essential seedling structures have been damaged (infection is particularly apt to occur in rhubarb in which case retests

may be advisable).

Abnormal seedlings include those that have : (1) A stubby root or no

primary root, provided there is weak secondary root development; (2)

a malformed hypocotyl, which may be twisted, thickened, or shortened; (3) deep cracks or lesions on the hypocotyl extending into the

conducting tissues; (4) both cotyledons, or one cotyledon and epicotyl

broken off; (5) two enlarged cotyledons, but hypocotyl short and

usually malformed; (6) decayed cotyledons or hypocotyl, provided

they are not the result of improper test conditions; and (7) various

combinations of the above-named abnormal types.

057116-52 12
EXAMINATION FOR NOXIOUS-WEED SEEDS

OBJECT AND NATURE OF TEST

The object of a noxious-weed seed examination is to correctly identify and determine the rate of occurrence of those weed seeds regarded

as noxious or particularly objectionable. In seed testing, the rate of

occurrence means the actual number of each named kind of noxiousweed seed that occurs in the sample being examined. For labeling

or other purposes, this information is transposed to a "per ounce" or

"per pound" basis. The noxious-weed seed examination is often regarded and conducted as a part of the purity analysis, primarily because of the similarity of methods used in conducting the two tests

and the fact that the same analysts conduct both tests. However, it

is common practice among seed-testing laboratories not to make noxious-weed seed examinations as a part of the purity analysis unless

specifically requested to do so.

STATE AND REGIONAL LISTS OF NOXIOUS-WEED SEEDS

Each State as well as the Federal Government has established, by

law or regulation or both, a list of noxious-weed seeds. These combined lists show that there are approximately 140 kinds or species

of noxious weeds in the United States. Efforts have been made by

Federal and some State seed-control officials to set up noxious-weed

seed lists on a logical basis by geographical and ecological regions.

Although this movement has met with considerable success, there is

still much to be desired in bringing about more practical and uniform

noxious-weed seed lists. Analysts are often at a loss to know the

particular kind of weed seeds to look for when making a noxiousweed seed examination. In State laboratories, analysts who conduct

tests for farmers or for control purposes will ordinarily be concerned

with the noxious weeds of their own State. State, commercial, and

private analysts who perform service testing will usually have to be

informed regarding the States into which the seed is to be shipped

so that the noxious-weed seed requirements for such States may be

met. Since most of the work of Federal analysts relates to seed control activities, information is readily available either from the rules

and regulations under the Federal Seed Act or from the noxiousweed seed lists of the States.

SIZE OF SAMPLE

A particular lot of seed may contain many seeds of a certain kind

of noxious-weed seed or it may contain only an occasional one. In

testing a lot of red clover seed containing only 18 dodder seeds per

pound, the 5-gram sample used for purity analysis might possibly

contain no dodder seeds and if only this sample were examined for

the presence of noxious-weed seeds the lot might be sold as "dodder

free." To avoid such possibilities it is necessary to use considerably

larger samples for noxious-weed seed tests than for purity determina172
TESTING AGRiCULTÜRAL AND VEGETABLE SEEDS 173

tions. The minimum weight of working samples for noxious-weed

seed examinations are shown in the third column of table 3, under

Rules for Seed Testing, in the Appendix.

There is no constant ratio between the sizes of the samples used for

purity tests and those used for noxious-weed seed determinations. In

fact, the ratio decreases gradually from 1: 50 in the case of sample size

for purity of 1/2 S^^^ to 1:1 in the case of sample size for purity of

500 grams. In other words, as the sample size for purity increases

(large-seeded kinds) there is less difference in the two sample sizes.

When the noxious-weed seed examination and purity analysis

are made at the same time, the amount analyzed for noxious-weed seeds

only can be reduced to the difference between the amount given in the

rules and the amount used for the purity determination. For example,

if a purity analysis is made on crimson clover seed only 40 grams

need be examined for noxious-weed seeds, because 50 grams (total required for noxious-weed seed examination) minus 10 grams (amount

required for purity analysis) equals 40 grams. The numbers of each

noxious-weed seed found in the 10-gram analysis and in the 40-gram

examination are added together and the total represents the number

found in 50 grams.

The rules for seed testing do not give any guide with respect to

the number of decimal places or of significant places to which samples

that are to be tested for noxious-weed seed shall be weighed. In the

absence of specific instructions, it is recommended that samples be

weighed and calculated to the nearest 0.5 gram when the sample size

is 25 or 50 grams, and to the nearest whole gram for sample sizes of

100 to 500 grams.

CONDUCTING THE EXAMINATION

The sample is reduced to the proper size by a mechanical divider

or other acceptable method described under the heading "Procedures

for Determining Purity Composition." The procedure for making

the examination is essentially the same as the hand separation procedure described for the purity analysis and the two tests must be

carried out in the same meticulous and painstaking manner.

Some analysts choose to use a hand lens for all noxious-weed seed

examinations regardless of the size of the seed being examined. It is

not essential to use the lens in the examination of large seeds, but it

should always be kept close at hand for the critical examination of

questionable seeds. A hand lens should always be used in making

noxious-weed seed examinations of the kinds of seeds requiring a

sample size of 25 or 50 grams. A reading glass may be used for the

determinations on those kinds of seeds requiring a sample size of 150

to 500 grams for examination; or, no magnification may be required

for the larger seeds if the characters of the weed seeds, for which the

sample is being examined, are quite distinct from those of the crop

seeds.

If 30 or more noxious-weed seeds of a single kind are found in the

purity analysis (or in an amount equal to the sample size for purity

analysis when only a noxious-weed seed examination is made) the

sample need not be examined further for that kind of seed. At this

point, the amount of the crop seed in which the 30 weed seeds were

found is weighed and the rate of occurrence is determined on that
174 AGRICULTURE HANDBOOK NO. 3Ô, U. S. DEPT. OF AGRICULTURE

basis. However, the analysis must be continued for other noxiousweed seeds. Should 30 seeds of a second or third kind be found before

the entire sample is analyzed, examination for each of these kinds

of seed msij be discontinued in accordance with the above procedure.

INTERPRETATION OF SEEDS

Any sample may contain seeds about which there is question (1)

regarding their identity or (2) as to whether they are weed seeds or

inert matter. In each instance the seed or seedlike structure must be

examined critically with a hand lens or under a stereoscopic microscope, depending on the degree of magnification required.

The rules governing the interpretation of noxious-weed seeds are

the same as those applicable to common weed seeds. Likewise, the

same interpretations apply to both groups of weed seeds. Consequently, the reader is referred to pages 49 to 52 for a detailed treatment

of this subject. Accurate identification and proper interpretation of

noxious-weed seeds is so important thatthe analyst is justified in going

to great lengths to attain accuracy. As compared with the purity

analysis, relatively more seeds should be dissected, caryopses of

grasses removed from glumes, and comparisons made with known

seeds, when necessary.

EXPRESSING THE RATE OF OCCURRENCE

Upon completion of the examination the record will show the number of each kind of noxious-weed seed found in the number of grams

examined. This can be converted to a "per ounce" basis by dividing

the number of grams examined into 28 and multiplying by the number

of weed seeds found; to convert to a "per pound" basis divide the

sample weight into 450 and multiply by the number of seeds found.

Actually, the number of grams per ounce is near 28.5 and the number

per pound is near 454, but 28 and 450 are close enough for computations

of this kind.
ORIGIN OF SEEDS

IMPORTANCE OF ORIGIN DETERMINATION

Some crops produced in a particular area have characteristics that

are a result of the environment as determined by temperature, rainfall,

and altitude. Certain varieties are often grown to the exclusion of

other varieties because of their adaptation to local conditions. In

some cases plants grown from seed produced in one region may be

susceptible to a disease that is prevalent in another region ; conversely,

certain areas may have diseases that would be harmful if introduced

into another region. Because of these factors, it is important to know

the origin of certain crop seeds.

The importance of origin is recognized in State and Federal seed

laws that require the origin of specified seeds to be stated on the label

attached to the seed. The Federal Seed Act requires that imported

alfalfa and red clover seed shall be stained in certain proportions with

colors that indicate the origin or the general adaptation of the seed

in the United States.

An experienced seed analyst can usually determine the origin of

the seed by a careful examination of extraneous material, such as weed

and other crop seeds, that may be present in the sample.

SIZE OF SAMPLE FOR ORIGIN DETERMINATION

The size of sample to be examined for origin cannot be definitely

specified. The usual practice is to continue the examination until

conclusive evidence is found. This may be found in a very small

sample or it may require examination of the entire sample submitted.

However, iiE no evidence is found in about 1 pound (approx. 450 to

500 grams) of seed such as alfalfa or clover, it would appear that

little or no useful purpose would be served by further search.

EVALUATION OF IMPURITIES

Many factors must be taken into consideration in making a determination of origin. The general appearance of a seed sample in

many cases suggests the possible origin, but this is seldom entirely

reliable. Factors such as ability to withstand cold temperature, freedom from disease, and other genetic or varietal characters which are

sometimes associated with origin usually cannot be determined from

an examination of the seed. The most dependable conclusions may

be drawn from the impurities carried by the seed sample, such as

weed seeds, other crop seeds, or the character of the inert matter. The

weed seed content usually furnishes the most important clue. It must

be emphasized that extreme care must be exercised in evaluating the

evidence presented by the examination.

The following points should be kept in mind at all times when

making an examination :

1. Weed seed impurities are seldom identical in all crops from the

same general region. The difference in cultural requirements, time

175
176 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

of harvest, methods of threshing, and cleaning may influence the

character of the extraneous seeds carried with the crop seed.

2. The fact that a species is listed as characteristic of one locality

does not necessarily mean that the plant does not occur elsewhere.

In other regions it may occur only sparingly and the possibility of

its appearance in a sample of crop seed is practically negligible.

Or, a plant may be fairly abundant in an area but the prevalent

cultural practices may prevent its introduction in cultivated fields.

3. It is seldom that all weeds listed as characteristic of a certain

region are present in any one seed sample, and conclusions must be

based, in part, on the combination of weed seeds represented in

the sample.

4. The frequency of occurrence of the different species of seeds

may vary from season to season.

5. A new species may become established over a period of time

and make its appearance as an impurity in crop seeds. Weed seeds

are being constantly distributed into other areas as a result of their

being carried with agricultural seeds, feeds, hay and straw, and by

birds, wind, w ater, and other means. Sometimes weeds become established in areas where they have not been found before. When this

happens, it is necessary to adjust the list of weeds used as indicators

of origin.

6. A new region of seed production is sometimes developed and

a new combination of weed seed impurities is introduced.

Some of the incidental seeds found in seed from the Southwestern

States occur also in seed from South America. Also, seed of South

American origin (Argentina and Chile) sometimes carries impurities

identical with those of southern Europe or South Africa. Many of

the common weed seeds of central Europe may be found in seed of

New Zealand origin, as well as of northern France. In many cases

these plants were likely introduced in cultivated fields with imported

crop seeds. This possibility should at all times be borne in mind, and

the complete picture, rather than the individual kind of seed, should

be considered in making a determination of origin.

When the representative impurities have been removed from a

seed sample, they may be classified into three general groups:

(1) Species that are confined to a limited area and would not be

expected to occur from any other source. (2) Species of somewhat

wider distribution which, although not typical of any region when

considered singly, are very helpful in making a determination when

found in combination. (3) Species of such general distribution

that they may appear in crops from many sources and consequently

have no significance in determining origin.

MAJOR SEED-PRODUCING REGIONS

The seed impurities in groups (1) and (2) above, considered together, may usually be referred to one of six major regions of production: North America, Europe, southwestern Asia, South America,

South Africa, and New Zealand.

These general regions, particularly Europe and North America,

may then be roughly divided into smaller areas in which the same

climatic conditions prevail. Thus, if the incidental weed seeds indicate general European origin, the combination of seeds present may
TESTING AGRICULTURAL AND VEGETABLE SEEDS 177

further suggest either north central and eastern Europe (including

Komania, Poland, Hungary, Russia, and Czechoslovakia), or southern Europe (including Italy, southern France, Spain) and Turkestan.

Within these more restricted areas considerable overlapping may be

expected and seeds of plants of very local distribution have to be

relied upon to delimit the smaller areas of production.

The seed-producing regions of North America fall roughly into

seven geographic divisions.

The Pacißc Northwest, including, in general, that portion of British

Columbia, Washington, Oregon, and northern California lying west

of the Cascade ranges.

The Southwest, including middle and southern California, Arizona,

New Mexico, and extending into southwest Texas, and southwest

Oklahoma.

The Intennoimtain region, including eastern Washington, eastern

Oregon, northeastern California, Idaho, Utah, western Montana,

western Wyoming, and western Colorado.

The Great Plains area, extending from central Canada southward to Texas, and from the Eocky Mountains east to about the

ninety-seventh meridian.

The North Central, the region east of the ninety-seventh meridian

and north of the Ohio Eiver.

The Northeast, the general region to the east and north of the State

of Ohio.

The Southeast, the States east of the ninety-seventh meridian and

south of the Ohio Eiver.

It is not always possible to distinguish between the seeds from

States within a geographic division. With experience, however, it

will be found that the weed impurities of the smaller subdivisions

present a rather definite pattern, and fairly reliable conclusions may

be drawn as to the place of origin of the seed.

LIST OF SEED IMPURITIES AVAILABLE

A list setting forth the more significant impurities to be expected

in both domestic and imported seeds of certain grasses and legumes,

particularly alfalfa and red clover, is being prepared and may be

obtained from the Grain Branch, Production and Marketing Administration, U. S. Department of Agriculture, Washington 25, D. C,

when completed.
TESTING FOR TRUENESS OP VARIETY

SCOPE OF VARIETY TESTING

The term "variety" means a subdivision of a kind which is characterized by growth, plant, fruit, seed, or other characters by which it

can be differentiated from other sorts of the same kind ; for example.

Marquis wheat, Flat Dutch cabbage, Manchu soybeans, Oxheart

carrot, and so forth.

At the present time the testing of crop seeds for trueness to variety

is carried on to some extent by the Federal seed laboratories and a few

State seed control agencies. Variety testing is not carried on by seed

control agencies in the United States on as large a scale as that in some

European countries.

PURPOSE OF VARIETY TESTING

Since most crops cannot be identified as to variety on the basis of

seed characteristics alone it is often necessary to make growing tests

for varietal identification.

Federal and State laws require that labeling of seed as to variety

shall be correct. It is important to the growler to be able to select and

obtain a variety of seed adapted to his needs.

AUTHENTIC SAMPLES FOR CONTROLS

Whenever possible authentic seed of known origin, of the same

variety as that being tested, should bs grown beside the variety in

test for purposes of comparison. The two samples should be planted

at the same time and given identical cultural treatment. This authentic seed grown for comparison is commonly referred to as a

"check." Seed for check plantings should be obtained from the most

reliable sources possible. These sources include the person, firm, or

agency that developed or introduced the variety, as well as reliable

seed firms and agencies known to have authentic seed of the variety.

Sometimes when two or more varieties are very similar, it is desirable

to obtain and grow check samples of all the similar varieties with the

sample being tested.

NUMBER OF PLANTS TO GROW

The number of plants to be grown for a variety test is a matter

which has not been standardized. In variety tests conducted by the

Federal seed laboratories an effort is made to obtain at least 200 plants

of most crops. Those crops which produce large plants such as tomato, pole bean, and the cucurbits require so much field space that the

number of plants grown is usually limited to 100 for each test. The

greater the number of plants obtained for judging, the more reliable

the results will be.

Clark {12) made a study of the number of plants for a variety test

and concluded that the magnitude of discrepancies which may occur

178
TESTING AGRICULTURAL AND VEGETABLE SEEDS 179

when fewer than 50 plants are included is so large that such tests

should be avoided if possible. He also concluded that the increase

in precision obtained by including more than 100 plants in a test is

relatively slight, and that when plants require considerable space

and care the expense of larger plantings is not justified. If too few

plants are obtained, the planting loses its value as a representative

of the lot of seed being tested and therefore is of little value.

TESTING IN THE FIELD

Most variety tests, particularly those carried out on a large scale,

are made in the field. It is necessary that the best possible plants

be obtained in a A^ariety test so that the characteristics typical of the

variety may have optimum conditions to express themselves. This

requires (1) growing the plants in areas where the crop is adapted,

(2) growing the plants under the best possible accepted cultural

practices, and (3) growing the plants during the proper season.

It is necessary to grow the plants under the above-named conditions

in order to : ( 1 ) Prevent the plants from shooting to seed or "bolting,"

as spinach, lettuce, and many species of Brassica do in hot weather ;

(2) obtain proper diagnostic color characteristics, such as zoning in

beet roots and pigmentation in lettuce leaves; (3) eliminate as far as

possible damage due to insects and diseases which are more harmful

in certain seasons in some localities; and (4) assure a period sufficiently long for the crop to mature.

In some cases, seed must be planted in a greenhouse and the young

j)lants transplanted to the field at a later date.

Growing of plants under poor cultural conditions, disease conditions, unfavorable environmental conditions, and in areas of heavy

insect infestations may alter their development to an extent that would

make accurate variety determinations uncertain. An example of

failure to exhibit typical characteristics when crops are grown under

poor cultural conditions is the suppression of the savoying character

in some vegetables, notably spinach, cabbage, and Swiss chard. Savoying is the wrinkling and curling of the foliage of some varieties.

When not well grown this characteristic may scarcely develop at all

and the variety may not be recognized. Sometimes improperly grown

plants may not be typical of the variety, but resemble another variety

so closely as to make correct identification difficult or impossible.

An example of this is the Fordhook Giant variety of Swiss chard.

Poorly grown and insufficiently fertilized, it may not develop the

deep green color which is characteristic of the variety, but may make

yellow green leaves and appear identical to the variety Lucullus. Or,

it may not only be pale in color, but may lose, to a large extent, the

extreme savoying of the foliage and thereby be mistaken for a smoothleafed variety. Such tests should be discarded and the results disregarded.

When seeds of many crops are planted directly in the field it is

necessary to thin the plants to the accepted spacing in order to provide

for normal growth. In testing for varietal identification thinning

should be done only for proper spacing between the plants. Thinning

should not be done on the basis of size, vigor, or appearance of the

young plants because, in the case of mixed varieties, selective thinning

may decrease the proportion of one or more varieties below^ its actual
180 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

rate of occurrence and increase the rate of occurrence of other varieties.

In such a procedure the mature plants which are to be judged for

variety will not be representative of the lot of seed being tested. In

order to eliminate possible bias in the thinning operation it is good

practice in variety testing to thin the plantings early; if possible,

before varietal characteristics begin to appear.

TESTING IN THE GREENHOUSE

Greenhouse testing can be of considerable importance in making

variety determinations. A greenhouse is not only necessary for starting plants which are to be set in the field at a later date, but complete

tests of some kinds of plants can be made, particularly during seasons

when they cannot be grown in the open. Also, special conditions rnay

be provided in the greenhouse which aid in variety testing and Avhich

cannot be duplicated in the field.

The length of day or photoperiocl may be increased by use of artificial light in the greenhouse. The additional light alters certain

characteristics of some plants in ways which permit rapid varietal

identification.

An ordinary 100-watt Mazda lamp over one or two flats in the

greenhouse is sufficient to induce these changes. Care should be taken

that the lamp is not so close to the plants as to damage them or dry

the soil. The distance between the plants and the lamp may need to

be increased one or more times during the test period. Precaution

should be observed in growing plants under continuous light in the

greenhouse to be certain that light does not reach other greenhouse

plants nearby, as some may be very susceptible to low intensities of

supplemental light and possibly develop abnormally. Undoubtedly,

regulation of the photoperiod in greenhouse tests may serve as a

useful tool in variety testing of many kinds of seeds which are not

discussed in this manual.

Biennial sweetclover, which normally does not flower until the

second year in the field may be brought into flower in a period of a

few weeks in the greenhouse when grown under continuous light,

thus permitting an actual count of yellow blossom and white blossom

plants. A complete test of sweetclover may be made within a period

of 10 to 12 weeks. The lights should be turned on the plants every

evening from the time the seedlings emerge. Flowering may take

place when the plants are anywhere from 6 to about 12 inches in

height. The plants may have single unbranched stems and take

up so little space that as many as 200 may be grown in a single greenhouse flat. In a flat 12 by 24 inches at least a dozen rows may be

planted, rather thickly. As soon as some of the plants show flower

color, they should be pulled out and counted, thus providing more

growing space for the remaining plants. Counts should be made

every 2 to 4 days until all have flowered.

Although some soybean varieties may be identified by seed characters alone, many cannot. Greenhouse plantings can be helpful in

such cases. Seedling characters serve to distinguish some varieties

when grown under normal light. Certain varieties can be brought

into flower at an early date by increasing the photoperiod with supplementary artificial light, thus making it possible to identify the

plants. Others can be held in the vegetative condition by decreasing
TESTING AGRICULTURAL AND VEGETABLE SEEDS 181

the normal daylight period. Characteristics which have been found

of value in identifying varieties of soybean in the seedling stage include the following: (1) Size and color of hypocotyl; (2) shade of

green of seedling; (3) size and shape of cotyledons 8 days after planting; and (5) pitting or lack of pitting on underside of cotyledons.

Annual rape grown under continuous light in the greenhouse may

develop flower buds within 3 weeks. The test period may be reduced

even more if the terminal bud is dissected before it opens, to determine

whether it is a flower bud or vegetative bud. When grown under the

same conditions, winter rape will remain in the vegetative state and

not produce flowers. Seeds of the two kinds are difficult to distinguish

and the rapidity of the greenhouse test is helpful in differentiating

them.

Variety tests of onions may be made in the greenhouse during the

winter. However, the short winter photoperiod prevents bulb formation. Continuous supplemental light causes the onion to form bulbs,

making it possible to observe their shape and color for varietal

determination.

Abruzzi and Eosen rye respond differently when grown in the greenhouse under continuous light. Plants of the Rosen variety do not

head out within 90 days after planting, whereas over 70 percent of

the Abruzzi plants will head out or will be ready to head out within

that period.

Partial tests without obtaining mature plants may be carried on

in the greenhouse and may give information indicating that complete

tests should or should not be made in the field. Such incomplete

tests which do not serve definitely to identify a variety are frequently

of value in that they demonstrate that a certain lot of seed cannot

be of the variety claimed. An instance of this kind would be a mixture of seed of red and green cabbage. In the seedling stage (before

the true leaves have begun to develop) the cotyledonary leaves of the

red cabbage will be edged with red and the midvein and stem will be

red, whereas in the seedlings of the green cabbage these areas will be

green. Varieties of yellows resistant cabbage may be distinguished

from nonyellows resistant varieties by inoculating seedlings in the

greenhouse and observing them in order to determine the numbers

that are killed and not killed.

Some tomato varieties differ from others in their shades of green in

the seedling stage. Also, the leaves of the potato-leaf varieties are

different in shape from those of other varieties in the seedling stage.

Such evidence is of a negative nature, proving that a lot of seed cannot

be of a certain variety ; however, itis usually not possible to tellto what

variety the seed does belong.

Greenhouse seedling tests have an advantage in that large populations may be obtained in very small growing areas in a short time.

Sterilized soil should be used whenever possible. It is possible that

seedling tests in the greenhouse may be of value in testing many kinds

of seed and the benefits to be gained appear to justify more experimental work along these lines.

JUDGING THE CROP

Judging the crop for trueness to variety and making notes on it is

commonly called "reading" a test. Readings must be made at the
182 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

proper times because some varietal characteristics become indistinct

when not observed soon enough, or the characteristics may not have

had time to develop if read too early. In many cases observations

must be made at several dates during the development of the plants

in order to note varietal characteristics of a transitory nature. For

example, the uprightness or spread of tomato plants, which is a diagnostic character of some varieties, must be noted before the plant

becomes heavy with fruit and sprawls on the ground. A thorough

knowledge of the characteristics of the variety and good judgment

are necessary when identifying plants which are not definitely and

obviously of a recognized variety. These plants may be of a degenerate stock, outcrosses, or may have suffered some type of injury.

The person making the readings must determine whether such plants

are merely poor stock, but within the variety range, or whether they

are beyond the limits of the variety. He must keep in mind that they

may be true to variety but altered by injury from cultivators, insect

damage, or other causes to the extent that they no longer have their

natural appearance. Familiarity with the variety under test is essential for the person making the readings.

A variety test may show any of the following results : (1) All plants

may be of the variety as labeled; (2) the entire sample may be of a

variety other than as labeled; (3) there may be a mixture of plants

of one or more varieties in addition to the variety labeled; (4) there

may be plants beyond the range of variety, commonly referred to as

"off-type" plants; or (5) there may be related weeds such as weedy

species of Brassica in crops of the genus Brassica,

Because of confusion, in some cases resulting from similar names

and synonyms, it is essential that the person making the test should

be absolutely sure of the characteristics of each variety he is testing,

and, furthermore, he should be sure that he has a sample of the correct

variety for check planting.
TESTING FOR MOISTURE

The moisture content of seeds is one of the most important factors

influencing their retention of viability and general appearance. It

is frequently desirable to know the moisture content of seed immediately after harvest, prior to storage or shipment, and at other times,

in order that the seeds may be stored or shipped under conditions

favorable to retention of viability. For these reasons seed-testing

laboratories are sometimes called upon to test seeds for moisture or to

offer information regarding methods of testing for moisture. A

brief summary of available information on this subject may serve as

a guide to those interested in testing seeds for moisture content.

Methods for determining moisture in seeds may be roughly

classified into: (1) Basic methods in which the moisture is driven

out of the seeds by heat and measured by the loss in weight

of the original material, or the weight or volume of the condensed

moisture; and (2) practical methods designed for rapid routine work

and standardized against one or more of the basic methods. Even

the basic methods should be considered rather empirical because all

the moisture probably cannot be driven out of seeds without at the

same time driving out small amounts of other volatile constituents,

or causing chemical changes in the material that would result in weight

changes that in turn would introduce errors in the moisture determination. In applying any method, therefore, it is necessary to adhere

closely to the prescribed procedure in order that the results of all tests

made by that method will be comparable. It also follows that tests

made by different methods may, in many instances, not be strictly

comparable.

Except for the cereal grains and a few other seeds there is a conspicuous lack of well recognized or "official" methods for determining moisture content. Eecognized and suggested basic methods for

determining moisture in various seeds are outlined as follows :

BASIC METHODS

AIR-OVEN METHODS

An air-oven method in which a weighed portion of the finely ground

material is heated in an air oven for 1 hour at 130° C. and the loss

of weight determined, is the official basic method under the official

grain standards of the United States for determining moisture in

all grains except corn. It is also the official basic method under the

official rice standards of the United States for determining moisture

in rice. If the initial moisture of the grain or rice is in excess of 13

percent a two-stage procedure is used in which a weighed portion of

grain is partially dried to a moisture content of less than 13 percent

before grinding, and the loss of weight in this preliminary drying is

determined. The partially dried grain or rice is then ground and a

weighed portion dried for 1 hour at 130° C. In calculating the moisture content of such grain or rice the moisture losses in both stages

of the procedure must be taken into consideration. Complete details

183
184 AGRICULTURE HANDBOOK XO. 3 0, U. S. DEPT. OF AGRICULTURE

for making moisture tests by this air-oven method are given in Service

and Kegulatory Annomicements No. 147 (^7).

One of the official methods of the Association of Official Agricultural

Chemists for determining moisture in grain is an air-oven method in

which a weighed portion of the finely ground grain is heated in an

air oven for 2 hours at 135° C. and the loss of weight determined.

Complete details for making moisture tests by this air-oven method

are given in the Official Methods of Analysis of the Association of

Official Agricultural Chemists (J).

Leendertz (3S) has suggested an air-oven method in which the

ground seed is heated for 105 minutes at 130° C. as a suitable method

for ryegrass, beet, spinach, parsley, carrot, lettuce, chicory, and

various Brassica seeds. For onion and radish seeds he suggests heating the material for 12 hours at 105° C.

Any of the above-mentioned air-oven methods should prove to be

reasonably satisfactory for most seeds except those that contain more

than albout 25 percent of oil or that contain oil having an iodine number higher than about 150. Seeds with a high oil content usually

cannot be satisfactorily ground without loss or gain of moisture;

and seeds containing oil of high iodine number should be tested by a

method not requiring grinding of the seeds, since the oil in the ground

material will oxidize readily on heating which in turn will cause a

gain in weight that will interfere with the accuracy of the moisture

determination. In all instances care should be taken to avoid any

appreciable loss or gain of moisture during the grinding process. It

is safer to use a two-stage procedure when the moisture content is in

excess of about 13 percent.

WATER-OVEN METHOD

The official basic method for determining the moisture content of

corn under the official grain standards of the United States is a wateroven method in which a weighed portion of the unground corn is

heated for 96 hours in a water-jacketed oven maintained at the temperature of boiling water (90° to 100° C.) at an atmospheric pressure

of 760 mm. The moisture content is determined from the loss

of weight during heating (^7). This method is also the official basic

method for determining moisture in dry peas and beans under the

official standards of the United States for these commodities.

VACUUM-OVEN METHOD

One of the official methods of the Association of Official Agricultural Chemists for determining moisture in grain is a vacuum-oven

method in which a weighed portion of the finely ground grain is heated,

until no appreciable further loss of weight occurs (usually about 5

hours), at 98° to 100° C. in an oven in which a partial vacuum is

maintained at a pressure equivalent to 25 millimeters of mercury or

less. The moisture content is determined from the loss of weight

during heating (S). This vacuum-oven method should prove to be

reasonably satisfactory for most seeds with the exceptions noted above

for seeds of high oil content or that contain oil of high iodine number.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 185

Seeds that contain more than about 25 percent of oil or that contain

oil having an iodine number higher than about 150 present a special

problem in moisture testing. Perhaps the most satisfactory method

for such seeds is the vacuum-oven method outlined above except that

the seeds should not be ground. The time required to attain constant

weight under such circumstances may be considerably longer than

5 hours.

TOLUENE DISTILLATION METHOD

Another of the official methods of the Association of Official Agricultural Chemists for determining moisture in grain is the toluene

distillation method in which a Aveighed portion of the finely ground

grain is boiled in toluene in an apparatus that condenses the volatilized

materials, collects the condensed water in a tube, and returns the condensed toluene to the boiling flask. The boiling is continued as long

as any water continues to accumulate in the tube provided for that

purpose, and the moisture content of the grain is calculated from

the volume of water condensed {S), This method should prove to

be reasonably satisfactory for most seeds that can be satisfactorily

ground without any appreciable loss or gain in moisture.

PRACTICAL METHODS

In certain types of practical work it is necessary to make moisture

tests more quickly than can be done with any of the above-mentioned

basic methods. Arbitrary practical methods standardized against one

or more of the basic methods have been devised for this purpose. In

general, the results obtained by such methods are likely to be less

accurate than those obtained by the basic methods, but they may be

sufficiently accurate for most practical purposes. The most commonly

used of these methods are described briefly as follows :

THE BROWN-DUVEL DISTILLATION METHOD

For many years moisture content was determined in the routine

inspection of grain by heating a weighed portion of unground grain

in oil to a definite temperature attained in a definite period of time.

The moisture volatilized by this heating is condensed, then collected

and measured in a graduated cylinder. The method is arbitrary and

the exact procedure to be followed for each kind of grain in order

to obtain results equivalent to those obtained by the applicable official

basic oven method has been determined. This method is described

in Bulletin No. 1375, U. S. Department of Agriculture (IS).

The Brown-Duvel method should be applicable to most seeds but

before it can be used it would be necessary to determine the exact

procedure necessary for each kind of seed in order to obtain results

equivalent to those obtained by an appropriate basic method. The

proper procedures have been established for wheat, corn, oats, rye,

grain sorghums, barley, buckwheat, flaxseed, soybeans, emmer, rice,

beans, peas, mustard seed, cottonseed, and peanuts (shelled).

The Brown-Duvel moisture tester has been largely replaced by

electric moisture meters in the routine inspection of grain, but it is

still used under various conditions of testing in which electric meters

cannot be depended on to give reliable results.
186 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

ELECTRIC MOISTURE METERS

Electric moisture meters are now widely used in routine work for

the determination of moisture in grain. They have a great advantage

in speed over all other methods for determining moisture. Most of

these instruments are based on measurements of either the conductivity

or the dielectric properties of the grain. Both the conductivity and

the dielectric properties of any kind of grain depend primarily on

the moisture content and temperature of the grain, but they also are

affected to some extent by many other variable factors. For this

reason electrical methods cannot be depended on to give reliable results

under all circumstances.

It is probable that the moisture content of most kinds of seeds can

be determined with a fair degree of accuracy under most circumstances by means of electric moisture testers. In using any electric

moisture tester, however, it is first necessary to calibrate the instrument against an accepted basic moisture-testing method. Separate

calibrations must be made for each kind of seed, and in the case of

some kinds of seed it is also necessary to make separate calibrations

for individual classes, varieties, or varietal types. Because of the

errors inherent in electric moisture-testing methods, each calibration

should be based on the testing of a large number of samples, covering

a wide range in inoisture content, obtained from as many different

points of origin as possible, and preferably representing the crops of

at least several years. It is obvious, therefore, that a large amount

of work is necessary before a reliable calibration table or chart can be

prepared for use in testing any kind of seed with any electric moisture

tester. Much work has been done in calibrating certain electric

moisture meters for use with the various cereal grains but relatively

little has yet been accomplished in this field for most other kinds of

seed.
TOLERANCES

DEFINITION AND NECESSITY OF TOLERANCES

If an entire seed lot could be tested, its true value would definitely

be ascertained ; however, this is neither feasible nor ordinarily possible. Thus, in seed testing the quality of the lot must be determined

from a sample that represents the entire lot. Owing to the time and

facilities involved small samples must usually be tested. The size of

the sample to be tested is an important factor in determining the

quality of the lot because the determinations become less accurate as

the sample size is reduced.

It is well known that results of tests cannot be exactly duplicated

on repeated testing of another portion of the same sample or by testing additional samples from the original seed lot. This is true, because no two subsamples drawn from the master sample or from the

seed lot are exactly alike. This expected variation in samples is due

to the nonuniform distribution of seeds and other particles in the seed

lot and is usually referred to as sampling variation.

Thus, sampling variation is normal, even in seed lots which are

relatively uniform, and the laws of probability can be applied to the

results of tests to predict the expected variation. When the approximate sample size is known, or when it is a standard quantity as set

forth in the rules, the expected variation can be calculated for the

different percentages of purity and germination, and for the number

of noxious-weed seeds, for any degree of certainty or probability

desired.

In many statistical treatments of data several results are averaged

to get the mean of all the tests made and the statistical inference is

that the mean is the correct value plus or minus a calculated amount.

In seed testing we ordinarily deal with only one-half the range of

variation—that is, we either add or subtract the calculated amount

(tolerance) to the results of a test or to a fixed standard, but not both.

For example, the pure seed tolerance for alfalfa having a purity of

97.0 percent is 1.18 percent. If 97.0 percent is a standard or fixed

number any test result as low as 95.82 percent would be within tolerance of 97.0. Although not of much importance in seed testing

it is nevertheless true that any test result as high as 98.18 percent

is also within tolerance of 97.0.

In most seed-testing work the result of a test is not compared with

a fixed standard but the result of a single test is compared with that of

another single test. In this case neither test can be regarded as more

valid than the other. However, the expected variation between two

tests, conducted independently, has been calculated for each percentage of pure seed, weed seed, and so forth and for the number of noxious-weed seeds. If the results of two such tests are within the calculated tolerance it can be concluded that each represents a valid tCvSt

on a representative sample drawn from the seed lot. If, on the other

hand, the two results are not within tolerance it cannot be concluded

that either represents a correct test (plus or minus the tolerance) of

957116—52 13 187
188 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

the seed. However, either party may be able to show, by repeated

tests, that his test result represents an accurate statement and that the

other test could not possibly represent seed of equal quality.

Thus, in seed testing the tolerances represent (a) the expected variation between a fixed standard and the extreme limit of calculated

variation, and (h) the expected or normal variation between two tests

conducted independently of each other. The value of the seed lot

may be better or worse than the result of a valid test to the extent of

the tolerance. . .

Statistically calculated tolerances are not expected to cover variation

in results caused by experimental error, differences of interpretations,

or lack of uniformity in seed lots. However, in some instances, rather

arbitrary and empirical factors^ have been introduced into the tolerances which may cover some variations of this nature.

PROBABILITY OR DEGREE OF CERTAINTY

In the above discussion reference has been made to calculating

tolerances to a predetermined degree of certainty, often referred to as

probability. In calculating the tolerances for pure seed (or any other

component) the tolerances may be so wide that in 100 trials of the

same bulk of uniformly blended seed at least 95 would be within

tolerance. This degree of certainty is referred to as P==0.05 or 1: 20

and means that no more than 1 in 20 trials would be expected to be

outside tolerance. As the tolerances are increased there is less chance

that any test result will be outside the tolerance range. If the

tolerances are calculated to P=0.01 as has been done and published

in the Canadian Methods and Procedures of Seed Testing {10), there

is not more than 1 chance in a 100 that the result of a valid test will

fall outside the tolerance range. The choice of the probability used

in calculating the tolerance is arbitrary and determined by the nature

of the data and the use to which these data will be put. In seed

testing and seed regulatory activities a probability statement of

P=0.05 has been generally accepted. Once the degree of certainty

is adopted the limits of tolerance can be read directly from published

tables. Probabilities of P=0.05 and P=0.01 are referred to as

significant and highly significant, respectively.

PURE-SEED TOLERANCES

Pure-seed tolerances are calculated from the formula

0.6 +(^0.2X^j^\ In this formula a represents the percentage of

the component being considered (pure seed, crop seed, weed seed,

inert) and h represents the difference between this percentage and 100.

Because the distribution of the particles in chaffy grasses is not

so uniform as in free-flowing seeds an extra tolerance is added to

that calculated by the above formula. Tlie additional tolerance is

found by multiplying the regular tolerance (calculated by the formula

given above) by the lesser of a and & divided by 100. Tolerances

for other crop seeds, weed seeds, and inert matter for both free-flowing

seeds and chaffy grasses are calculated by the formula and procedure

given above, except that 0.2 is substituted for the 0.6 outside the

parentheses. These purity tolerances are not based entirely on

statistics but might be regarded as arbitrary tolerances. The 0.6 and
TESTING AGRICULTURAL AND VEGETABLE SEEDS 189

0.2 outside the parentheses are arbitrary values selected to cover or

compensate for chance errors inherent in seed testing. The remainder

of the formula constitutes a sliding or shifting value to cover systematic errors due to sampling variation*

GERMINATION TOLERANCES

The germination tolerances used in the United States are purely

arbitrary and are somewhat wider for germination percentages of

60 to 100 than statistical tolerances for 400 seeds at P=0.05. They

do not take into consideration the number of seeds tested nor any

particular degree of certainty. The constant germination tolerance

of 10 for all tests falling below 60 percent is entirely out of line with

statistical tolerances. Statistical tolerances gradually decrease as

the percentages of germination increase above 50 percent and decrease

below 50 percent. For example, tolerances calculated to a degree of

certainty of 1 to 20, on the basis that 2 independent tests are inade

on 400 seeds per test, would decrease from 6.9 for 50 percent germination to 1.8 at 1 percent germination. No doubt, differences in interpretation of the germination test leading to wide variations in test

results have been an important factor in retaining the arbitrary

germination tolerances.

NOXIOUS-WEED SEED TOLERANCES

The rate of occurrence of noxious-weed seeds is stated in numbers

per unit weight. It is important to determine the rate of occurrence

accurately. The accuracy of such a determination depends on the

number of noxious-weed seeds found rather than on the size of the

sample examined. When a small number of individual particles are

concerned, as is usually the case in testing for noxious-weed seeds, it

is not possible to state definitely the amount of seed to be examined

for a desirable given degree of certainty. However, in order that

results of different tests on the same lot of seed may be compared it

is necessary to use samples of standard size. When comparing the

results of a test with a fixed standard, it is necessary to base the statement in the standard on the same quantity as tested. For example,

a seedsman claims 90 dodder per pound in lespedeza seed but the

analyst may find 15 in 50 grams. The 90 dodder in a pound represents 10 in 50 grams and thus 15 should be compared with 10—not 135

(9X15) with 90.

The noxious-weed seed tolerances are based on the Poisson

distribution and calculated to a certainty of P=0.05 by the formula

Y=X+ 'vA3.841X+l, where Y is the number of noxious-weed seeds

for which the tolerance is being calculated and X is the lowest limit

of the tolerance range.

The wording of the State seed laws Avill have to be used as a guide

in determining whether tolerances are to be applied to each kind of

noxious-weed seed or to the total of all kinds found, or both.

TOLERANCES FOR FLUORESCENCE TESTS AND OTHER 400- TO 1,000-

SEED SEPARATIONS

Various kinds of tests are made on 400 to 1,000 seeds, such as the

fluorescence test of ryegrass, varietal separations, and separations of

similar kinds of seeds. Although the present rules for seed testing
190 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

specify that 5 grams of sweetclover seed shall be used in the mottled

seed test, it is entirely possible that this amount may be reduced in

the future to a specific number of seeds. In all these cases where a

specific but relatively small number of seeds is used special tolerances

must be recognized. Tolerances for 400- to 1,000-seed separations

have been calculated to a certainty of P= 0.05 and appear in the

Appendix.

In all these tests a previous purity test is made in which the sample

is separated into seed having similar characters, other crop seed, weed

seed, and inert matter. The 400- to 1,000-seed test is used to separate

the seeds having similar characteristics. Therefore, the tolerances

mentioned above cover only the latter part of the test. It has been

learned by experience that tolerances obtained by addition of the regular pure seed tolerances and the 400- to 1,000-seed tolerances are too

wide. Consequently, only i/2 of the pure-seed tolerances are added

to the 400- to 1,000-seed tolerances.

APPLICATION OF TOLERANCES

There are certain allowances permitted in connection with the testing and labeling of seed which should not be confused with tolerances.

Such allowances as including 5 percent of straw-colored Sweet Sudan

grass seed with pure seed and 5 percent of fluorescent ryegrass seedlings with perennial ryegrass are not tolerances. Likewise, some

State laws permit specified numbers of noxious-weed seeds above

which none are permitted or above which labeling is required. These

are definite allowances and not tolerances. If tolerances are not used

with these allowances, the only completely safe way seedsmen can

label seed to comply will be to subtract the tolerance from the allowance and refrain from selling any seed showing noxious-weed seeds

in excess of this amount. If the seedsman uses test results falling

within the tolerance range of a fixed standard, he is running a risk

that the true value of the seed lot is below the standard and that a

control laboratory may obtain results outside the tolerance range.

In making a single test one never knows the position in the tolerance

range in which his test result will fall.

Since tolerances are provided to take care of the unavoidable variation in test results they are not to be applied prior to labeling by adding them to the results found by test. Tolerances should never be

used for the purpose of permitting labeling to show higher quality

than is actually found by the test.

The various tolerances used in connection with the rules for seed

testing are listed in the Appendix, pages 356 to 368.
CALCULATIONS, RECORDS, AND REPORTS

CALCULATION OF LABORATORY TEST RESULTS

PURITY

The rules for seed testing provide that the percentage by weight

of each component of the pure seed separation shall be determined by

totaling the weights of all components and dividing the sum (and

not the original weight) into the weight of each. This is illustrated

in the following example :

Weighty

Component Grams Percent

Pure seed 4.945= 94.92

Other crop seed 0.120— 2.30

Inert matter - 0.050= 0.96

Weed seed - 0- 095== 1. 82

Total weight 5.210 100.00

The only exception to the above procedure is when the working

sample is 500 grams. In this case, the other crop seed, weed seed,

and inert matter are weighed. The original weight is divided into

each of these to determine the respective percentages. The pure

seed percentage is determined by subtracting the sum of the percentages of inert matter, other crop seeds, and weed seeds from 100 as

illustrated in the following example :

Original sample weight=502.8 grams

Weightf

Component Grams Percent

Pure seed

Other crop seed 2.56 0.51

Inert matter 3.25 .65

Weed seed 1.74 .35

1.51

Pure seed=100.00—1.51=98.49 percent

Procedures and examples of recording results and calculating percentages of mixtures based on 400- to*l,000-seed separations are given

under the heading "Application of Purity Procedures to Specific

Groups of Seeds" for the following kinds: Bluegrasses; bentgrasses;

sorghums; oats ; Sweet Sudan grass; and millet. Specific procedures

and examples of calculating results are also given in the same section

for a 5-gram separation of mottled seeds of sweetclover and the fluorescence test of ryegrass.

The above-named special tests are made by first conducting a regular purity analysis and then taking a small subsample from the pure

seed and making a critical separation of either a definite number of

seeds or a weighed amount. The percentages of the regular purity

analysis are determined in the usual way; then determine the percentage of each component in the subsample and multiplj^ each of the

latter by the percentage of pure seed in the regular purity analysis.

191
192 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

Example : Bluegrass mixture Weighty

a. Regular purity analysis- ~ ^--^^

Pure seed ^'^AQO ^r

Other crop seed -Oüöf .To

Inert matter • J-f^«^ iz. 4U

Weed seeds __1I_ ^

1.1000 100. 00

J>. 1,000-seed separation- ^^^^^^ «¿^^f^^ ""Z"'^'

Poa pratensis °^^ °^' ^^

Foa compressa ^^^ ^i; }.}.

Poa trivialis "^ ^'^^

1, 000 100. 00

[83.50=71.64

85.80X 11.50= 9.87

I 5. 00= 4. 29

85.80

^ Report the following : ^^^^^^^

Pure seed— ^

Kentucky bluegrass '¿- ^^

Canada bluegrass ^- °]

Other crop seed (0.75+4.29) 5.04

Inert matter If- ^^

Weed seeds ^'^^

100. 00

GERMINATION

Four hundred seeds should be used for each germination test. In

cases where it is impossible to separate varieties or indistinguishable

kinds of pure seed, such as ryegrass and sweetclover, only one germination test is made and the result is interpreted to represent the

germination of each kind or variety tested. When the kmds of pure

seed can be separated a complete germination test is made on each

kind.

The numbers of germinating seeds should be recorded on the test

card at the time of each count. At the end of the test period, the

hard seeds (if present) are recorded. The numbers of germmated

and hard seeds are then totaled and each divided by 400 (the number of seeds tested) to obtain the percentages of germination and

hard seed.

Although not regularly reported, the number and types of abnormal

seedlings present should be recorded. Eetests are sometimes avoided

by an explanation of the types of abnormal growths. Notes should

also be made on the record card regarding any unusual condition

of the sample, such as the presence of excessive mold, live or dead

insects, evidences of frost damage, decayed seeds, chemical injury

from fungicides, or the presence of disease. For example, in recording the results of germination tests for beans which have been mechanically damaged, the record card should include information

under the following headings :

1. Normal (usually the only percent reported besides the hard seed).

2. Abnormal:

a, Baldheads (all types).

h. Other abnormals (various types including those with malformed hypocotyls and stubby roots).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 193

G. Splits (those with cotyledons too broken for growth to continue beyond the formation of enlarged leaves within the cotyledons,

and vestiges of root and hypocotyl).

3. Decayed seed.

4. Hard seed.

If fungi are present, their presence should be indicated. Any other

unusual conditions of the seed should also be noted.

LABORATORY RECORDS

Records of purity and germination tests are preferably written

in ink ou small cards which should be filed for future reference. The

form will vary with the needs of the laboratories. Copies of suggested purity and germination forms are given on pages 369 and 370

in the Appendix.

REPORTING THE RESULTS OF TESTS

The report of results of the purity analysis should give all calculated percentages. Results of germination tests are reported in

round numbers, fractions of one-half of 1 percent or more being

regarded as the next whole number; and fractions of less than onehalf of 1 percent being dropped. For example, an actual germination of 90.50 percent would be reported as 91 percent, and a germination of 90.49 as 90 percent.

The analyst must frequently decide which of two results to report

when a sample is tested for germination by more than one method

or when a, check test of any kind is made. The Standardized Test

Committee has recommended that the results of the different tests

be averaged, if within tolerance. If not within tolerance, the higher

i*esult should be reported. This appears to be a logical procedure

and it is followed in the Federal laboratories. In no case should

tolerances be added to the percentages reported for either the purity

or germination test.

Noxious weeds are reported as the number found in the weights

examined. This may be expressed as number per unit weight, in

grams, ounces, or pounds.

Incidental weed seeds should be listed and may be reported as

the number or percentage found in the weights examined; or the

figures may be converted and reported as the number present per

pound. In the Federal laboratories the incidental weed seeds are

merely listed and not reported by number or percent found, unless

they are present to the extent of over one-half of 1 percent by weight.

In all cases the laboratory report should be clear and concise and

any pertinent information regarding the seed covered by the report

should be given.

The purity and germination report forms may vary, depending

on the requirements of each laboratory. Copies of two report forms

used by the Federal laboratories are illustrated in the Appendix, pag-es

371 and 3T2. ^ ^
IDENTIFICATION OF SEEDS ^

The identification of seeds is a specialized field of taxonomic botany

that is still comparatively new. Although the character of the seed

remains remarkably constant under varying environmental conditions,

its use as a classification feature has been overlooked throughout the

years and information on the identification of seeds is still very

meager. Seeds of plants are rarely described in taxonomic publications and the seeds, when illustrated, usually show little diagnostic

detail.

Just before the turn of the century, the need for identification of

seeds arose as a result of the desire on the part of growers and

dealers for information on the trueness to name of seeds to be planted,

and the nature of the extraneous seeds that the crop seeds might

carry.

The present study includes: (1) Seeds of all field crops, other

than vegetable, except those that offer no problems in seed identification, such as cotton and peanuts; (2) seeds of plants declared

primary or secondary noxious weeds under the seed laws of the different States; (3) common field weeds, including relatively harmless

weeds that could be confused with closely related noxious weeds;

and (4) newly introduced weeds. Included also are some seeds found

only in imported seed that may serve to indicate origin, or that may

in time become naturalized in this country.

It was impossible to consider such a large number of plants in

as great detail as the amount of available material and its usefulness

would warrant, and the question of which to include and which to

omit presented a real problem. The principal criterion used in determining the selection was the economic importance of the plant, or

its suitability as a representative of the family to which it belongs.

It was necessary to limit the number of species in the following

fenera: Agropyron^ Agrostis, Avena, Festuca (fine-leaved species),

*anicum, and Brassica, These have been published in detail elsewhere, as listed under "Available Publications on Seed Testing,"

page 318.

Most of the cereal and forage crops belong to the grass or legume

families, and seeds of these species are fully described and illustrated

on i)lates I to XII and plates XVIII to XXIII, respectively. Descriptions are also included of the more important groups in the

mustard, morning-glory, and pink families. The more important

* Pioneer work on seed identification in this country was conducted by F. H.

HiUman, formerly on the staff of the Federal Seed Laboratory, who made outstanding contributions in this field. In 1918, with the assistance of Helen H.

Henry, he prepared the first comprehensive treatise on crop and weed seeds

under the title "The More Important Forage-Plant Seeds and Incidental Seeds

Commonly Found With Them." This publication consisted of 15 photographic

plates of seed drawings of 370 species of plants. The 15-plate set was reissued

by the Department of Agriculture in 1935, and it is still considered a standard

reference on seed identification in seed laboratories in this country. Use has

been made in this Manual of many of these illustrations, as well as many

hitherto unpublished drawings by Mr. Hillman and Miss Henry. The additional

illustrations appearing in this Manual were prepared by Regina Olson Hughes.

194
TESTING AGRICULTURAL AND VEGETABLE SEEDS 195

species in 51 other families are illustrated. The names and plate

numbers of these families and species may be found in the Lists of

Plant Names, pages 373 to 423.

It frequently happens in descibing seeds that there is no term

that specifically applies, and the usual botanical terminology must

be used in a modified sense. These terms are defined in the Glossary

in the sense in which they are used throughout this publication.

GRAMINEAE (GRASS FAMILY)

(Pis. I-XII)

Flowers of the grass family (fig. 63) are arranged in spikelets consisting of a shortened axis (rachilla) and from two to many tworanked bracts. The lowest bracts, called the glumes, are empty. The

bracts above (lemmas) each bear a single floAver (pistil and stamens),

and between the flower and the rachilla is a second bract, the palea.

The spikelets are usually aggregated in spikes or panicles at the ends

of the main culm or branches.

fi

u.

FiGTJEE 63.—^A spikelet and florets of bluegrass : a, Spikelet as it api)ears at

maturity; &, the spikelet spread apart, showing the jointed rachilla, the two

empty glumes at the base, and four mature florets above ; c, back view of a floret,

showing the lemma (1) ; d, front view of a floret, showing the edges of the

lemma (1), the palea (2), and the rachilla segment (3); e, the caryopsis,

showing the embryo area at the base.

The fruit of the grass family is the ripened floret, consisting of a

caryopsis or grain enclosed in the two chaffy scales, the lemma and

palea. In most of the species considered herein, the spikelets are

several-flowered and a joint of the axis (rachilla) persists at the base

of the palea and is often an important diagnostic feature. In the

species having one-flowered spikelets the rachilla is lacking or merely

a rudiment, as in Agrostis for example. The palea has two nerves

or keels, and the character of the hairs along the keels is a useful
196 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

distinguishing feature in certain species. The caryopsis lies in the

palea with the hilum (point of attachment) toward it. The small

embryo lies in a distinct area at the base of the caryopsis on the side

toward the lemma, opposite the hilum. The caryopsis may be hard,

as in bluegrass, or soft, as in orchard grass.

The lemma and palea may be more or less adnate to the caryopsis

in many species, and the unit popularly considered the seed is the

ripened floret—the caryopsis with its lemma, palea, and rachilla

segment. In some species the lemma and palea are loose and the

caryopsis becomes hulled in the threshing process, and in such cases

the hulled grain is referred to as the seed. The term "seed" as used

in this publication refers to the unit considered the seed of a particular

species as it appears in commercial channels.

The size of seeds in a sample may vary considerably. The sizes

stated in the seed keys represent an average seed insofar as is possible,

and they are intended to show the relative sizes of the different species

in a genus as an aid in their determination. For convenient reference,

the genera are arranged alphabetically, and seed keys are provided

for the larger groups.

AGROSTIS 5—BENTGRASS

(PI. I, 1-8)

The spikelets of Agrostis are one-flowered, and the rachilla is

usually not prolonged. When present, it may vary from fairly long

and hairy to a mere prickle. These rudimentary rachilla segments do

not appear to have any diagnostic value.

Seeds of Agrostis are too small to be recognized as to kind without

magnification. An examination of a small quantity of seed with a

good hand lens or a low-power binocular microscope will show certain features that will give a clue to the identity of the seed sample,

but for a more critical determination of the individual seeds that

make up the bulk a magnification of about 40 is necessary. Commercial seed lots ma^^ contain a variable proportion of hulled grains. As

a rule, these cannot be identified as to species with certainty.

Forms of A, temiis^ colonial bent, are sometimes called browntop,

Rhode Island, Prince Edward Island, New Zealand, Astoria, and

Highland bent. The last-named two are the principal horticultural

varieties in use at present. Astoria bent is distinguished from common

colonial bent chiefly by the larger size and more oblong shape of the

seeds. This difference is apparent when seeds are viewed in quantity,

but no way has been found whereby the smaller seeds of Astoria bent

could be distinguished with certainty from common colonial bent.

Highland bent appears to be an aberrant form and may be a distinct species instead of a horticultural variety of A, tennis as it is now

classified. The main distinguishing features of the seed are the uniform spindle-shape and deeply notched tip of the palea. The Dryland browntop of New Zealand appears to be identical with Highland

bent.

There are numerous strains of A, pdlustHs^ creeping bent, formerly

known as carpet bent. Many of these are reproduced vegetatively

because no seed is available. Seed of other forms, such as seaside

bent, is available commercially.

^ A more complete study of Agrostis, with photographic plates of seed drawings, may be obtained by purchase from the Grain Branch, Production and

Marketing Administration, U. S. Department of Agriculture, Washington 25, D. C.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 197

PRINCIPAL SOURCES OF SEED

A. alba, redtop : Illinois; incidental in bentgrass from other sources.

A, tennisj colonial bent or browntop: Khode Island; Canada; New

Zealand ; western Europe.

A, tennis^ Astoria bent : Washington ; Oregon.

A. temds^ Highland bent: Oregon; New Zealand.

A. 2?alustTÍ8^ creeping bent: Oregon; Washington; Rhode Island;

Connecticut; Canada; New Zealand.

A. canina^ velvet bent: Rhode Island; Connecticut; Canada; western Europe.

A. elliottiana^ Elliott bentgrass: Incidental in redtop, Illinois

grown.

A. hiemalis^^ winter bentgrass : Incidental in redtop, Illinois grown.

A, scabra^ ticklegrass : Incidental in bentgrass from west coast.

A, exarata^ spike bent: Incidental in bentgrass from west coast.

BULK DISTINCTIONS OF THE COMMERCIAL SPECIES

Seeds buff color, highly glossy; lemmas predominantly 3-nerved

and awnless, not keeled on the back ; palea tips truncate or with broad,

shallow notch.

A. alba, redtop (pi. I, 1).

Seeds buff color and glossy to silvery and lustrous; lemmas predominantly 5-nerved and awnless, keeled on the back ; paleas broad,

narrowed to a shoulderlike apex.

A. palustris, creeping bent (not illus.)

Seeds pale buff color, lustrous to somewhat glossy; uniformly

spindle-shaped ; basal hairs and awns infrequent; paleas with narrow,

deep V-notch.

A. tenuis, Highland bent (not illus.).

Seeds dull gray, weathered looking ; lemmas 3-nerved ; geniculate,

twisted awns from near the base common.

A. tenuis, colonial bent (pi. I, 2).

A. tenuis, Astoria bent (not illus.).

Paleas so reduced they appear to be lacking ; grain very soft ; lemmas long-awned from about the middle or lower.

A. canina, velvet bent (pi. I, 5).

SEED KEY

A. Palea from one-half to slightly exceeding the caryopsis ; caryopsis hard.

a. Lemma stiff, glossy and buff-colored, or slightly lustrous and silvery;

awns mostly lacking or, if present, short and straight to semigeniculate, sometimes twisted and geniculate in the variety Highland.

aa. Lemmas rounded or slightly flattened on the back, apex 3- to

4-nerved (rarely 5-nerved) ; paleas mostly loose, tapering from

near the base.

Apex of paleas truncate or broadly notched ; lemma oblong or

narrowly elliptic, length 2 mm. or more, width % mm. ; basal

hairs long and appressed or spreading, short and stubby, or

lacking; awns when present arise well above the middle of

lemma A. alha, redtop (pi. 1,1).

Apex of paleas deeply V-notched; lemma uniformly spindleshaped, length 1% to 2 mm., width % mm. ; basal hairs

mostly lacking, occasionally long and spreading ; awns when

present arise from near the base to about the middle of

lemma A, tenuis var. Highland bent (not illus.).
198 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

hd. Lemmas keeled above the callus, apex 5-nerved (rarely 3-nerved) ;

paleas mostly loose, narrow abruptly near the top, apex various

but not notched as above; lemma ovate-lanceolate or elliptic,

length 1% to 2 mm., width % mm.; basal hairs mostly short

and stubby, sometimes longer and spreading, or lacking ; awns

when present arise from near the top of the lemma.

A. palustris, creeping bent (not illus.).

Ö. Lemmas light gray, with a dull, weathered texture; awns frequent,

twisted and geniculate, sometimes short and straight, arise from

near the base to about the middle of lemma.

Lemmas not keeled above the callus or only slightly so, apex 3-

nerved ; paleas thin, mostly adherent to the grain, apex variously

notched ; lemmas lanceolate to oblong, length 1% to 2 mm., width

% mm. ; basal hairs mostly short and copious, sometimes longer,

or lacking.

A. tenuis var. colonial bent (pi. I, 2).

A. tenuis var. Astoria bent (not illus.).

B. Palea reduced to a minute scale; caryopsis soft or semifluid.

a. Lemmas coarsely granular, especially along the 5 prominent nerves,^

thin and transparent, usually obscuring the deeply grooved grain;

length 1% to 2 mm., width less than % mm. ; awns long, threadlike

or much reduced, arise about three-quarters from the base of lemma ;

basal hairs long, copious, appressed.

A, elUottiana, Elliott bentgrass (pi. I, 6).

Ô. Lemmas finely granular, thin and transparent, obscuring the grain or

partially so.

aa. Awns long, twisted and geniculate, sometimes straight, arising

about the middle of lemma or lower, sometimes lacking

in certain strains ; lemma 1^^ mm, long or more, width less

than % mm.; basal hairs short and stubby, sometimes

lacking A. canina, velvet bent (pi. I, 5).

&&. Awns lacking, or occasional in A. scahra.

Lemmas equal to grain or shorter, dull ; length 1 to 1^4 mm.,

width less than % mm. ; basal hairs lacking, or infrequent A. Jiiemalis, winter bentgrass (pi. I, 7).

Lemmas exceeding the grain, semipolished and smoother

than A. hiemalis; length 1% to 1% mm., width less than

% mm. ; awn when present straight and delicate, arising

about two-thirds from base of lemma ; basal hairs long

and copious A. scahra, ticklegrass (pi. I, 8).

c. Lemmas smooth, whitish, opaque, obscuring the grain, the margins

overlapping on ventral side in upper half; awnless seeds Xy^ mm.

long, % mm. wide; basal hairs short and sparse or lacking; awned

seeds 2 mm. long, i^ to % mm. wide, basal hairs long, appressed A. exarata, spike bent (pi. I, 3 and 4).

AGROPYRON e—WHEATGRASS

(PL I, 9-16)

Seeds of 12 species of Agropyron that are of economic interest are

described. These include the kinds now in production, certain native

and introduced species in experimental plantings, and species that

may occur as field weeds. The taxonomic status of three of the species—the so-called standard crested wheatgrass (formerly known as

A, cristatum)^ fairway (formerly considered a variety of A, crista-

^ A more complete study of Agropyron, with photographic plates of seed drawings, may be obtained by purchase from the Grain Branch, Production and

Marketing Administration, U. S. Department of Agriculture, Washington 25, D. O.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 199

tum)^ and intermediate wheatgrass {Ä, infermediiim)—is still somewhat uncertain.

It has been observed that seeds of commercial crested wheatgrass

are not uniform in character, and variation in plant types has been

observed in the field. In studying field plantings of crested wheatgrass Swallen and Kogler (U) report that about 95 percent of the

plants are of the A, desertorum type, and they consider the complex

as one species, A. desertorum^ retaining the already well-established

common name of crested wheatgrass.

Kegarding the fairway variety, Swallen and Eogler {44-) state

that this may be a species distinct from A. cristatum^ but for the

present it is being classified as A. cristatum, fairway crested wheatgrass. Compared with the standard crested wheatgrass, seeds of fairway are smaller with all lemmas glabrous and uniformly long-awned.

Commercial seed of A. intermedium, intermediate wheatgrass, including the variety Eee wheatgrass, consists of seeds which may be

considered typical of A, intermedium, with a variable proportion of

seeds that appear to be intermediate between A. intermedium and A,

trichophorum, hairy intermediate wheatgrass. Space permits showing only the more typical types of seeds in this complex. The field

plantings, as reported, yield a variable population. It has not been

determined whether these off-type forms are simple varieties of a

species or a natural segregation as a result of hybridization. There

appears to be some intergrading between A. intermedium and A.

trichophorum, and some authors consider the latter to be a variety of

A, intermedium rather than a distinct species.

Samples of A. smithii, western wheatgrass, sometimes contain a

trace of seed with lightly pubescent lemmas. This pubescent form

is now recognized as A, smithii var. molle and is reported to have

about the same distribution as the species. It is not known whether

the pubescence is a constant feature or whether the plant produces

both glabrous and pubescent lemmas. A separation of the two kinds

in a seed sample would be of doubtful value at the present time.

Seeds of ¿.riparium, streambank wheatgrass, and A, dasystachyum,

thickspike wheatgrass, may occur incidentally with crop seeds. Seeds

of both species have pubescent lemmas and are somewhat similar to

A, smithii var. molle in this respect. As pointed out in the seed key,

seeds of A, riparium are smaller and markedly flatter than J.. smithii.

The more widely distributed A. dasystaehyum is distinguished from

A. riparium chiefly by the long spreading hairs on the rachilla, the

acuminate or short-awned lemma, and somewhat larger size of the

seed.

Seeds of A, suhsecundum, bearded wheatgrass, another widely distributed species, may occur incidentally with certain crop seeds. The

seeds resemble slender wheatgrass somewhat but may be distinguished

by the bifid lemma and long awn.

For purposes of classification the seeds may be grouped on the basis

of pubescence into two groups : (1) Lemma pubescent; and (2) lemma

grabrous. Each group may be further divided on the shape of the

lemma, as keeled or rounded on the back. All measurements in the

seed keys that follow are approximate values representing the majority of seeds of the kind. Some deviation from these measurements

may be expected in any seed sample.
200 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

SEED KEY

Group I

Lemma Pubescent

A. Lemma keeled, at least on upper half; sinus U-shaped or broadly V-shaped.

a. Elliptic, length 8 to 10 mm., width 2 mm., apex narrowly truncate, midnerve projecting into a short, stout awn-point.

A. trichophorum, hairy intermediate wheatgrass (pi. I, 16).

1). Narrowly lance-shaped.

Length (excl. of awn) 6 to 7 mm., width 1 mm.; acute-pointed

or with awn i/4 to % the length of the lemma.

A, desertorum (in part), standard crested wheatgrass (formerly A. cristatum) (pL 1,14).

Length (excl. of awn) 8 to 10 mm., width 2 mm.; acuminate or

terminating in a short awn.

A. intermedium (in part), intermediate wheatgrass (pi. I, 15).

B, Lemma rounded on thé back, narrowly elliptic.

a. Sinus V-shaped.

Length (excl. of awn) 8 to 10 mm., width li/^ mm. ; awn from 1 or

2 mm. to 14 the length of the lemma, occasionally acute-pointed

and awnless ; lemma does not extend to keels of palea in lower

half ; rachilla hairs short, appressed ; seed flatter than the variety

molle, below A. riparium, streambank wheatgrass (not illus.).

Length (excl. of awn) 9 to 11 mm., width 1% to 2 mm. ; awn % the

length of lemma or shorter; rachilla hairs longer than in riparium; edges of lemma extend to keels of palea throughout, or

nearly so ; seed markedly thicker than riparium.

A. smithii var. molle, no common name (not illus.).

1), Sinus U-shaped.

Length (excl. of awn) 9 to 11 mm., width 2 mm.; acuminate or

with short awn point ; lemma does not extend to keels of palea

in lower half ; rachilla hairs long and spreading.

A. dasystachyum, thickspike wheatgrass (not illus.).

Group II

Lemma Glabrous or Sparingly Scabrous on Nerves Toward the Top

A. Lemma keeled, lance-shaped ; hairs on keels of palea short, stout, wide-spaced,

a. Length (excl. of awn) 6 to 7 mm., width 1 mm., acute-pointed or with

awn V4, to Ys the length of the lemma A. desertorum,

standard crested wheatgrass (formerly A. cristatum) (pi. I, 14).

&. Length (excl. of awn) 5 to 6 mm., width 1 mm. ; awn 1^ to % the length

of the lemma A. cristatum, fairway crested wheatgrass (pi. 1,13).

B. Lemma rounded or slightly flattened on the back, if keeled only slightly so ;

hairs on keels of palea not as above.

a. Rachilla hairs long and spreading; sinus mostly U-shaped.

Lemma oblanceolate, awnless or with very short awn ; length 8 to

10 mm. ; width 1% mm. ; callus hairs continuous across the back.

A. trachycaulum (A, paucifiorum), slender wheatgrass (pi. 1,11).

Lemma narrowly lanceolate, bifid ; awn about twice the length of

the lemma; length (excl. of awn) 8 to 10 mm.; width l^/^ mm.;

callus hairs mostly continuous across the back; palea markedly

shorter than lemma.

A, sudsecundum, bearded wheatgrass (not illus.).

&. Rachilla hairs short and appressed, minute and sparse, or lacking ; awn

% to % the length of lemma (shorter or lacking in intermedium and

elongatum).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 201

aa. Narrowly lance-shaped or elliptic.

Sinus V-shaped, occasionally narrowly U-shaped.

Rachilla flares out at the top, lies against keels of

palea; palea often grooved down the center, apex

deeply V-notched ; lemma (excl. of awn) 9 to 10 mm.

long, 1% to 1% mm. wide; callus hairs not continuous across the back; margins of lemma extend to

keels of palea throughout, or nearly so.

A, smithii, western wheatgrass (pi. I, 10).

Sinus U-shaped.

Ilachilla straplike, lies flat against the palea, usually

between the keels; palea smoothly concave or with

a longitudinal fold down the center, apex truncate,

roimded, or with shallow notch; lemma (excl. of

awn) 8 to 9 mm. long, li/^ mm. wide; callus hairs

mostly lacking, or short and few at outer ends;

margins of lemma usually do not extend to keels of

palea in lower portion.

A. repens, quackgrass (pi. I, 9).

Rachilla not straplike, lies against keels of palea or

between them; apex of palea truncate, rounded, or

slightly indented; lemma (excl, of awn) 9 to 10 mm.

long, 2 mm. wide; callus hairs short and sparse or

lacking ; margins of lemma extend to keels of palea

or nearly so.

A. intermedium, intermediate wheatgrass (pi. I, 15).

A. intermedium, Ree wheatgrass (in part) (not illus.).

dd. Narrowly oblong; sinus V-shaped or narrowly U-shaped.

Lemma 3-nerved at the top, apex truncate or minutely lobed,

length 10 to 12 mm., width 2 to 2^/^ mm.; apex of palea

truncate or obtuse, hairs on keels long, fine, close-spaced;

grain thick A. elongatum, tall wheatgrass (pi. I, 12).

Lemma 5-nerved at the top, awned; length (excl. of awn)

9 to 10 mm. or longer, width 1 to 11/2 mm. ; apex of palea

finely notched or obtuse, hairs on keels not long and dense ;

margins of lemma do not extend to keels of palea in lower

half; grain flat.

A. inerme, beardless wheatgrass (not illus.).

AIRA—HAIRGRASS

(PI. I, 17-18)

Two species of hairgrass are commonly found with crop seeds,

neither of which is of any economic importance. The spikelets are

two-flowered, disarticulating above the glumes. Both florets of a

spikelet are shown in the illustrations.

Aira elegans {A. cafillaris)^ fine hairgrass (pi. I, 17). The seeds

are 11/2 to 13^ mm. long, iy4 to 1/3 mm. wide; dark brown shading to

silvery white at the top ; lemma rounded on the back, the inroUed

margins partially obscuring the palea ; apex prolonged into two very

slender teeth.

The basal florets (shown in the two views at left in the illustration)

are awnless or with only short hairlike awns ; hairs at base silvery,

short and sparse, confined mostly to the outer ends of the callus;

rachilla short. Upper florets (shown in two views at right in illustration) have no rachilla; awns about 21/2 mm. long, geniculate and

twisted; basal hairs longer, mostly appressed, extend clear across

callus.

Aira caryophyïlea^ silver hairgrass (pi. I, 18). The seeds are 2l^

to 3 mm. long, 1^ mm. wide, awn 3 to 31/2 mm. long; in general appear-
202 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

ance resemble A. ¿legans but may be distinguished by the larger size.

In this species both upper and lower florets in the spikelet bear long.

geniculate twisted awns, but only the lower floret carries a rachilla

segment (shown in middle seed in the illustration) ; basal hairs long

and copious.

ALOPECURUS—FOXTAIL

(PI. I, 19-23)

Five species of Alopecurus are described, four of which are field

weeds. One species, A, pratensis^ meadow foxtail, is in limited cultivation.

The one-flowered, strongly compressed spikelets disarticulate below

the glumes so that the unit commonly considered the seed consists of

the ripened floret with its attached glumes. The glumes are equal or

nearly so, united at the base; ciliate on the keels and, in certain species,

on the lateral nerves. The species may be distinguished by the size

and character of the glumes and the relative length of the protruding

awn.

In commercial seed samples the ripened florets without the attached

flumes may sometimes be found. The smooth translucent lemma,

earing an awn from near the base, completely enfolds the flattened

grain, the margins united in the lower half; the palea appears to be

wanting. The caryopsis is golden yellow or dull brown, soft or semifluid, minutely wrinkled and striate lengthwise. The free grains may

occur with such crops as crimson clover, timothy, and the smaller

grass seeds.

SEED KEY

A. Spikelets 2 to 3 mm. long.

Awn of lemma geniculate ; glumes usually exceeding the lemma.

Awn approximately 3 mm. longer than the glumes.

A. gcniculatus, water foxtail (pi. I, 21).

Awn approximately 2 mm. longer than the glumes.

A. caroUnianus, Carolina foxtail (pi. I, 20).

Awn of lemma straight, frail ; glumes usually shorter than lemma.

Awn scarcely exserted beyond glumes.

A. aequalis, short-awn foxtail (pi. 1,19).

B. Spikelets 4 to 5^^ mm. long. ?

Awn of lemma geniculate, approximately 5 to 7 mm. longer than the glumes.

Glumes thin, long-ciliate on keels and lateral nerves ; scar small,

inconspicuous A. pratensis, meadow foxtail (pi. I, 22).

Glumes thick, granular, short-ciliate on keels and at base of nerves,

scabrous above ; scar large, prominent.

A. myosuroides, slender foxtail (pi. I, 23).

ANDROPOGON—BEARDGRASS

(PI. II, 25-32)

Eight species of Andropogon are described. Three of the species

are well-known range grasses: A, scoparius^ little bluestem; A, gerardi {A. fiwcatus), big bluestem ; and A. hallii^ sand bluestem. There

is some intergrading between A, gerardi and A. hallii. Seeds of the

two species are about equal in size and general structural features;

but the callus, rachis, and pedicel of A, hallii are usually more densely

pubescent than A, gerardi.

Four species now in experimental plantings are promising pasture

plants: A. ischaemwn^ Turkestan or yellow bluestem; A, sericeus^

Queensland beardgrass; A, nodosus^ angleton grass; and A, interonedius^ Australian bluestem.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 203

Ä, virginicus^ broomsedge, is a common weed of old fields in the

eastern half of the United States.

STRUCTURAL FEATURES

The spikelets are borne in pairs at each node of a jointed rachis. A

single joint of the inflorescence is the unit commonly considered the

seed. It consists of one fertile, sessile spikelet, and one pedicellate

spikelet, which may be either sterile or staminate, together with the

attached rachis segment. The rachis and pedicel of the sterile spikelets are often densely pubescent. In some species^ the sterile spikelet

is suppressed, only the pedicel being developed, as in A, scoparius (pi.

11,27).

Glumes of the fertile floret are hardened and awnless, completely

enclosing a thin and transparent lemma and palea. The transparent

lemma usually bears a bent or twisted awn from the apex or from

between the lobes at the apex. The awn is rather weak and easily

detached and would be mostly lacking in processed seed.

Sometimes a seed sample consists of seeds that have been hulled by

processing. The characteristic shapes and sizes of the free grains in

the different species are shown in the illustrations.

SEED KEY

A. Length (excL of awn) 5 to 9 mm. or more.

a. Back of lemma with broad longitudinal groove ; rachis joint and pedicel

expanded and cupped at the apex ; pedicels and callus densely villous,

especially in JialUi.

A. gerardi {A. furcatus), big bluestem (pi. II, 25).

A. tiallii, sand bluestem (pi. II, 26).

T). Back of lemma not grooved ; rachis joint cupped at the apex, pedicel

bearing a reduced sterile floret ; pedicels and callus villous.

Lemma with fringe of hairs across the back near the top, hairs

as long as lemma or nearly so.

A. sericeus, silky bluestem (pi. II, 31).

Lemma without fringe of hairs across the back near the top.

A. scoparius, little bluestem (pi. II, 27).

B. Length (excl. of awn) less than 5 mm.

a. Rachis joint and pedicel cupped at the apex, villous.

aa. Rachis joint and pedicel with a wide dark-colored groove down

the middle; lemma with a minute pit on the back.

A. intermedius, Australian bluestem (pi. II, 29).

OÔ. Rachis joint and pedicel not grooved; lemma not pitted.

Lemma with a few long hairs arising from cushionlike

bases near the top; shape obovate or oblanceolate.

A, nodosus, angleton grass (pi. II, 30).

Lemma sparingly pubescent below the middle, smooth above ;

shape narrowly lanceolate.

A. ischaemum, yellow beardgrass (pi. II, 28).

&. Rachis joint and pedicel not cupped at the apex, long and flexuous,

villous A, virginicuSf broomsedge (pi. II, 32).

ANTHOXANTHUM—VERNALGRASS

(PI. II, 33)

The spikelets of vernalgrass consist of one fertile floret enclosed

by two awned, sterile lemmas. The rachilla disarticulates above the

glumes, the sterile lemmas falling attached to the fertile floret. The

957116—52 14
204 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

fertile floret with the two attached sterile lemmas, as shown at the

left in the illustration, is the unit commonly considered the seed.

When found as an incidental seed with other crop seeds, the sterile

lemmas may be lacking as a result of processing, as shown at the right

in the illustration.

Two species are described: Ä, odoratmn^ a perennial, is sometimes

included in meadowgrass mixtures; and A, aristatum {A. puellii)^ an

annual. Both species may occur as incidental seeds with crop seeds.

A. odoratwn^ sweet vernalgrass (pi. II, 33) : The sterile lemmas

are about 3 mm. long, subequal, reddish brown, often yellowish at

the tip ; pubescent, the hairs long and appressed, arising to well above

the middle of the lemma; the first sterile lemma is short-awned from

near the apex, the second is awned from near the base, the awn twisted

and geniculate. The fertile lemma, enclosing the plump grain, is

2 mm. long or less, dark reddish brown, smooth and glossy.

A, aristatum^ annual vernalgrass (not illustrated) : The seed differs from sweet vernalgrass chiefly in the position of the pubescence

on the sterile lemmas. ^ In sweet vernalgrass the hairs extend to near

the top of the lemma; in annual vernalgrass the point of attachment

of the hairs usually does not extend higher than the middle of the

lemma. Both fertile and sterile lemmas of annual vernalgrass are

usually lighter in color than sweet vernalgrass.

APERA

Spikelets of Apera are one-flowered, disarticulating above the

glumes, the rachilla prolonged into a short bristle less than y^ i^ii^iin length. The lemma bears a long slender awn from near the apex ;

the lemma and palea equal or nearly so.

Apera spica-venti^ windgrass (pi. II, 34) : Lemmas are light

yellowish brown, sparingly hirsute above the middle; length 2 to

2y2 nirn. ; awn 2 to 3 times the length of the lemma ; the grain is soft,

yellowish. The seeds may occur incidentally with sweet vernalgrass

and similar crops.

ARISTIDA—THREE-AWN

(PI. I, 24)

The genus Aristida is characterized by one-flowered spikelets that

disarticulate above the glumes. The lemma is hard, convolute, with

a sharp-pointed callus at the base, and usually terminating in three

awns.

Aristida dichotoma^ poverty grass. The seeds are dull grayish

brown, flecked with dark brown or black; length (excl. of awn) 5 to 6

mm. ; sparingly pubescent on the midnerve ; central awn 3 to 6 mm.

long, spirally coiled and horizontally bent, lateral awns shorter ; callus

with a long tuft of whitish hairs at each end.

The seeds of poverty grass may occur with certain crop seeds from

the eastern half of the United States.

ARRHENATHERUM—OATGRASS

(PI. II, 35)

The spikelets of oatgrass are two-flowered, the lower floret staminate, the upper floret perfect, the spikelets disarticulating above the

glumes. The staminate floret, bearing a twisted geniculate awn.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 205

remains attached to the fertile floret at maturity, the whole appearing

as a single fruit, as shown in the illustration.

Arrhenatherum elatius, tall oatgrass (pi. II, 35) : Lemmas are 9

to 10 mm. long, light straw color, seven-nerved, minutely scabrous on

upper half, often with scattered long, whitish hairs on the lower half.

The staminate floret bears a long twisted, geniculate awn from near

the base, the fertile floret usually bears a short straight awn from

near the tip. This short awn is usually broken away in the seedcleaning process. The hairs at the callus are light-colored, long and

spreading.

The seed of oatgrass is sometimes hulled by processing. The hulled

grains are light yellowish, 4 to 5 mm. long ; in side view the dorsal,

or embryo, edge is nearly straight, the ventral edge is convex.

Tall oatgrass is grown as a meadow grass in the North and East.

An improved variety, A. elatius var. Tualatin, is going into production. The seed of this variety does not appear to be distinguishable

from the species.

AVENA 7—OATS

(PL II, 36-41)

Spikelets of Avena are 2 to 3 flowered, disarticulating above the

glumes and between the florets. The character of the abscission is an

important feature in distinguishing the species. The caryopsis or

grain is firmly enclosed by the hardened lemma and palea and hulled

grains are usually found only in seed that has been severely milled.

The hulled grain, however, may provide valuable diagnostic features.

Five species and a fatuoid form are illustrated and described : The

common cultivated oats, A sativa and A. lyzantina; wild oat. A, fatua;

slender oat. A, larhata; sand oat. A, strigosa; and a homozygous

fatuoid form that occurs with cultivated oats. The heterozygous

fatuoid is not included in this study.

CULTIVATED OATS

As reported, there are approximately 125 recognized agronomic

varieties of cultivated oats in this country, with many hundreds of

synonymous strains. The identification of these varieties and strains

is not a part of this study. In the illustrations the red oats group

{A, lyBantina) is represented by the varieties Fulghum and Red

Rustproof, the common or northern oats (A, sativa) by the variety

Victory (pi. II, 36, 37). The two groups may be roughly divided

on color and texture of lemma, but neither feature is entirely dependable. Distinction in color becomes evident when seeds are viewed in

quantity but in the individual seed it may not be so apparent. Generally speaking, the lemma of the sativa group is smooth, that of

iyBantina coarsely granular so that it grates on the forceps. The

two types are well represented by the varieties Victory and Fulghum.

IBetween the two extremes are finely granular, intergrading forms

that cannot be distinguished by this character alone.

' A more complete study of Avena, with photographic plates of seed drawings,

may be obtained by purchase from the Grain Branch, Production and Marketing

Administration, IT. S. Department of Agriculture, Washington 25, D. C.
206 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FATUOIDS AND WILD OATS

Fatuoids tend to resemble in size, color, and texture the variety

of oats with which they occur. In morphological features the homozygous fatuoid (pi. II, 38) bears a superficial resemblance to A.

fatua but the two kinds are readily distinguishable by size and shape,

and color may be helpful to some extent in making a determination.

A, fatua is usually gray or black, occasionally yellow, but apparently

there are no white and no real red. On the other hand, there are not

many kinds of black cultivated oats in the United States, and only

a very few gray. Consequently, unless the oat sample in question

is gray or black, the fatuoid would not be likely to exhibit that color.

There is perhaps one exception, an occasional black fatuoid may

appear in red oats, particularly in the variety Fulghum.

As reported, gray oats are rarely grown outside the South, New

York (the var. Cornellian), and adjacent States. The var. Columbia,

more reddish gray than the gray of A. fatua is grown rather widely

from spring seeding. Three varieties of black oats are grown but not

to any great extent : Tech, grown from fall seeding in Virginia ; Coast

Black, in certain small areas of California, mostly for hay purposes ;

Victor, in limited production in western Oregon and possibly in

other small areas where it is said to be favored for feeding race horses.

TYPES OF ABSCISSION

There are three general types of articulation of the spikelet from its

pedicel and of the florets from each other. (1) Complete abscission:

An absciss layer is developed between the floret and its pedicel or

rachilla segment so that the matured floret breaks off readily, showing a smooth, well-developed callus around a prominent basal cavity

(pi. II, 39). (2) Partial abscission : An absciss layer is not developed

around the entire base of the floret, usually only on the sides, whereas

a small portion on the front and at the back remains lightly solidified

with the pedicel and the floret does not break off smoothly at these

points. (3) Fracture: The points of articulation have become lightly

to completely solidified. The floret may break off more or less regularly along the line where the absciss layer would normally develop,

but there is no callus as in type (1) and the basal cavity is greatly

reduced or, as is common in the upper florets, the rachilla itself

breaks and a portion of the segment remains attached to the base

of the floret (pi. II, 36, 37, 41).

PUBESCENCE

The character of the basal hairs, rachilla hairs, and awns appears

to be fairly constant in the wild species and homozygous fatuoids,

but hairs on the lemma may vary considerably in individual plants of

a species. The awns are stout, geniculate, the bend usually well above

the tip of the lemma, twisted below. The* cultivated forms are

characterized by a reduction in awns and pubescence. The awns,

generally few in number, may be straight or semigeniculate and

twisted, the bend usually below the tip of the lemma. In the variety

Winter Turf the awns may be heavier than in most of the cultivated

varieties.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 207

CARYOPSIS

The shape of the caryopsis is very characteristic in the two groups,

the wild and the cultivated species. In edge view, the dorsal line

is nearly straight in cultivated oats; in the wild species and the

fatuoids the dorsal line is longitudinally arched and, A, harbata and

A, strigosa excepted, the caryopsis is markedly thicker through the

lower half.

In ventral view, all species except A, fatua are transversely arched

by two thick longitudinal folds with a deep groove between them.

The ventral side of A, fatua is flat, with a fine longitudinal groove^

Wild species and fatuoids that are awned show the imprint of

the awn as a distinct groove on the dorsal side of the caryopsis. This

groove appears to be lacking in cultivated oats. Just above the

embryo is a whitish area, the scutellum. It is interesting to note that

the scutellum is more or less distinct in all but A, fatua where it is

completely lacking or only a faint whitish line.

The character of the caryopsis is particularly helpful in distinguishing A, fatua and the fatuoids when other diagnostic features of the

floret are in doubt. The shape of the caryopsis is not entirely dependable as some degree of overlapping may occur, especially in terminal

florets. The ventral face and the scutellum appear to be fairly constant and may serve as reliable features in distinguishing the two

forms. In A. fatua the ventral side is flat, scutellum lacking or very

faint; in fatuoids the ventral side is transversely arched, scutellum

large, triangular, distinct.

SEED KEY

A. All florets of spikelet disarticulate by complete abscission ; all florets awned,

awn geniculate, the bend well above tip of lemma or equal to it, twisted

below.

a. Lemma terminates in two minute teeth; rachilla and base copiously

hairy, hairs long and stiff, basal hairs long and spreading or short

and bushy ; lemma with scattered long stiff hairs or completely devoid

of hairs.

aa. Seed broadly elliptic ; in edge view about twice as thick at base

of awn as at the base; caryopsis much thickened in lower

half, scutellum distinct Fatuoid, homozygous (pi. II, 38).

&Ö. Seed narrowly elliptic; in edge view only slightly thicker at

base of awn; caryopsis slightly thickened about midway,

scutellum lacking or only a faint whitish line.

A. fatua, wild oat (pi. II, 39).

Ö. Lemma terminates in two long bristles; lemma, rachilla, and base

copiously hairy, hairs long, stiff, spreading ; in edge view not evidently

thickened at the middle ; caryopsis slender, scutellum distinct.

A. l)arJ)ata, slender oat (pi. II, 40).

B. All florets in spikelet disarticulate by fracture.

a. Lemma acute, terminates in two minute teeth, awns when present

are straight or semigeniculate and twisted below, the bend usually

below the tip of lemma; caryopsis not prominently thickened in

lower half ; scutellum large, distinct.

aa. Lemma finely to coarsely granular, devoid of hairs or sparsely

hairy A. hyzantina, red or southern oat (pi. II, 37).

1)1), Lemma smooth to finely granular, devoid of hairs or only an

occasional hair.

A. sativa, common or northern oat (pi. II, 36).
208 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

&. Lemma acuminate, terminates in two long bristles, with distinct lightcolored nerves ; both florets awned, awns geniculate and twisted below ;

caryopsis shape as in A. fatua but smaller, scutellum large, distinct.

A. strigosa, sand oat (pi. II, 41).

AXONOPUS—CARPET GRASS

(PI. II, 42-43)

The single-flowered spikelets of the carpet grasses disarticulate below the glume, and the fertile floret with its persisting glume and

sterile lemma is the unit popularly considered the seed. The first

glume is lacking and the sterile lemma does not bear a sterile palea.

Fertile florets without the attached glumes and sterile lemmas are not

commonly found in cleaned seed.

Axonopus aßnis and A, compressus are very similar and intergrading forms may be expected. A, afflnis is the more widely distributed

of the two species and it is being utilized for lawn and pasture purposes in the South and Southeast. Seed in commercial channels at

the present time is likely to be of this species.

SEED KEY

Spikelet 2 to 3 mm. long ; sparsely long hairy along margins ; midnerve of glume

and sterile lemma wanting or faint.

Glume and sterile lemma obtuse or short-pointed, equaling or slightly

exceeding the grain— A. aS'^'^s, narrow-leaved carpet grass (pi. II, 42).

Glume and sterile lemma acute, exceeding the grain.

A, compresses, broad-leaved carpet grass (pi. II, 43).

BECKMANNIA—SLOUGHGRASS

Bechmannia symgacJine^ American sloughgrass (pi. II, 44) : The

spikelets are one-flowered, disarticulating below the glumes, the spikelet falling entire. The glumes are about 3 mm. long, laterally compressed, light straw color, deeply keeled and faintly wrinkled transversely, the acuminate apex of the lemma protruding between them

at the top. The grain is soft, and light yellow in color.

The seed may occur incidentally with crop seeds. The soft, hulled

grain is sometimes found in samples of timothy or similar meadow

grasses.

BUCHL0Ë—BUFFALO GHASS

Buchloë dactyloides^ buffalo grass (pi. II, 45) : The staminate and

pistillate flowers are usually borne on separate plants, the two inflorescences being strikingly different. The pistillate spikelets are

borne in curiously modified hard, whitish burlike heads. These burs

are the units commonly considered the seed.

Each bur consists of two to five or six spikelets held together by a

thickened base and surrounded by thick, hard, overlapping second

glumes, each of which terminates in three rigid, usually green-tipped,

acuminate lobes. As a rule, not all of the spikelets in a bur contain

caryopses. A good grade of seed will average 50 to T5 percent filled

burs.

Seed samples sometimes consist of caryopses that have been hulled

by processing. The hulled seeds are light brown, 2% to 3 mm. long,

ovate or broadly elliptic, and markedly thicker at one end.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 209

BOUTELOUA—GRAMA GRASS

(PL II, 46-48)

The spikelets of grama grass consist of one fertile floret with rudiments of one or more florets above it,^ the entire spikelet falling from

the glumes which remain on the rachis.

The gramas are native range grasses of the Great Plains that are

being utilized for regrassing purposes. Three of the more important

species are illustrated and described in the seed key that follows.

SEED KEY

A. Lemma of fertile floret keeled on the back.

a. Lemma glabrous or sparingly long-pubescent at the callus and along

the sharply keeled back, lustrous; lateral nerves exserted as short

awns; length (excl. of awn) approximately 4 mm., width i/^ mm.;

free grains thick, 3-angled B. graoilis, blue grama (pi. II, 47).

&. Lemma copiously short-pubescent at the callus and sparingly longpubescent above, duU and porous in texture ; lateral nerves exserted

as long awns; length (excl. of awn) 4 to 5 mm., width 1 mm.; free

grains obovate in dorsal view, in edge view the embryo side straight,

the hilum side convex B. hirsuta, hairy grama (pi. II, 48).

B. Lemma of fertile floret not keeled on the back ; length (excl. of awn) 5 mm.,

width 1 to 1% mm. ; midnerve a fine line, usually evident to the base.

a. Lemma flattened on the back, dull, minutely hispid at the top, glabrous below ; lateral nerves exserted as short awns ; free grains oblong in dorsal view, in edge view flat and straight.

B. curtipendula, side-oats grama (pi. II, 46).

BROMUS—BROMEGRASS

(PI. Ill, 49-57)

The spikelets of bromegrass are several-flowered, the rachilla disarticulating above the glumes and between the florets. The seeds of

commerce consist of the caryopsis within a lemma and palea and

the attached rachilla segment.

Four perennial species are in cultivation or being increased for

production : B, inermis^ smooth brome ; B, catharticus^^ rescue grass ;

B, marginatus^ mountain brome; and B. earinatuß^ California brome.

Eight annual species are included. Some of these have limited forage

value but for the most part they are considered field weeds. The

distinguishing features of these 12 species are set forth in the seed

The species B. secalinus^ B, commutatus^ B, japomcus^ and B. moUis

are closely related. Although they are recognized as distinct species,

the forms are separated only by arbitrary characters and some intergrading can be expected. The fully developed mature florets of the

three species are readily recognized. However, when the seeds occur

incidentally with crop seeds they may be immature, or the distinguishing features of lemma and palea may be damaged in the cleaning

process, and such seeds cannot be identified with certainty in all

cases. The distinguishing features of terminal florets of a spikelet

are often less well defined than in the lower florets. These terminal

florets, partly because of their smaller size, sometimes remain with

the cleaned crop seed and their positive identification is not always

possible.
210 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

B. seccdinus and B, commutatus each has a recognized variet}^

having pubescent lemmas ; B. secalinus var. velutinus and B, commutatus var. apricorum. In this country the two varieties are confined

to the Pacific coast and are comparatively rare.

Seeds of B, carinatus and B, marginatus are somewhat similar.

Seed of Bromar, an improved variety of B, nharginatus^ is shown in

the illustration (pi. Ill, 57).

SEED KEY

A. Lemma flattened dorso-ventrally, 3-nerved .or obscurely 5-nerved; length 9

to 12 mm., width 2 mm., awn lacking or, if present, 1 to 2 mm. long.

Lemma narrowly oblanceolate, not overlapping keels of palea, thin and

papery, short-pubescent near the base, glabrous above ; palea narrower

than the grain, v^ith a longitudinal fold down the middle, minutely pubescent, hairs on keels very short, fine, close-spaced; rachilla bristly pubescent; grains thin and flat Bromus inermis, smooth brome (pi. Ill, 55).

B. Lemma sharply compressed or folded laterally, obscuring the palea, thick

and stiff, 7 to 9 nerved ; length 10 to 15 mm. ; av^ned or awnless.

a. Long-awned ; width as folded 1% to 2 mm. ; in side view, slightly

broader above the middle.

Lemma appressed-pubescent, rarely glabrous ; awn 7 to 15 mm. ;

palea nearly equal to lemma; rachilla sparingly appressedpubescent B. carinatus, California brome (not illus.).

Lemma minutely hispid on midnerve at the top and sparingly

below ; awn 4 to 6 mm. ; palea mostly shorter than lemma ;

rachilla granular or minutely hispid.

B. marginatus, mountain brome (pi. Ill, 57).

Ö. Av^nless, or with awn 1 to 3 mm. long ; width as folded 2i/^ to 3 mm. ;

in side view, broader below the middle, flatter than marginatus.

Lemma minutely hispid, especially along the nerves, sometimes

almost glabrous; palea about % the length of lemma; rachilla

sparingly short-pubescent to glabrous, usually shorter than

carinatus and marginatus.

B. catharticus, rescue grass (pi. Ill, 56).

C. Lemma involute or compressed laterally in part, never flattened throughout, 5 to 7 nerved ; palea usually partially obscured by margins of lemma.

a. Lemma linear, long-awned, light to dark brown or purplish, terminates in two hyaline teeth 1 to 2 mm. long, or 3 to 5 mm. long in

ruhens and rigidus; palea markedly shorter than lemma, narrow,

tapering from the base.

aa. Lemma thin and papery, keeled and glabrous at the base, flattened and pubescent above; hairs on keels long (li/^ to 2

mm.), flne, and pointed, close-spaced, usually with shorter

hairs between; callus smooth and polished or with a few

hairs on each end.

aaa. Lemma pilose, in some forms glabrous or nearly so,

length 8 to 12 mm., width l^/^ mm., awn 12 to 15 mm. ;

apex of palea obtuse or minutely notched.

B, tectorum, downy chess (pi. Ill, 49).

ö?)i). Lemma hispid and sparingly long-pubescent near the

margins, length 12 to 15 mm., width 1 to 1% mm., awn

18 to 20 mm. ; palea terminates in deep V-notch.

B. rubens, foxtail chess (not illus.).

hb. Lemma stiff, more or less involute throughout most of its

length; hispid, especially along midrib and along margins;

hairs on keels of palea widespaced, shorter and broader at

the base than in rudens and tectorum; apex of palea obtuse or

truncate.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 211

aaa. Callus smooth and polished, or with a few hairs at each

end ; length of lemma 15 mm. or longer, width 1% to

2 mm., awn 15 to 20 or 30 mm.

B. steriUs, barren chess (pi. Ill, 50).

hhb. Callus white-pubescent over entire surface and on

lemma just above it ; length of lemma 25 to 30 mm.

or longer, width 2 mm., awn 25 to 35 mm. or more.

B, rigidus, ripgut grass (not illus.).

h. Lemma elliptic or narrowly obovate with attenuate base, more or less

involute or keeled in lower portion ; awns 8 to 9 or 10 mm., or 2 to 5

in secalinus,

aa. Palea markedly shorter than lemma, spatulate, with a minute

longitudinal fold down the middle, thin and partially adherent to grain, flat in upper portion with shallow concavity

below ; lemma thin and papery.

aaa. Lemma finely pubescent, mostly with transverse wrinkles between the nerves, apex distinctly notched ; the

fine nerves usually distinct to the base.

B, mollis, soft chess (pL III, 54).

hhd. Lemma glabrous or minutely pubescent at the top and

along margins, smooth or with transverse wrinkles

between the nerves ; apex minutely notched or obtuse ;

midnerve evident to the base, lateral nerves often

obscure B. japonicus, Japanese chess (pL III, 51).

1)1). Palea equal to lemma or nearly so ; lemma thick and stiff,

minutely pubescent toward the top and along margins.

aaa. Palea equal to grain, usually with a deep V-shaped

cavity, smooth or variously folded or wrinkled,

scarcely narrowed at the notched or obtuse apex,

usually narrower than the grain; lemma scarcely

broader than the grain, margins usually not overlapping keels of palea, midnerve evident to about the middle, lateral nerves obscure ; grain compressed laterally,

obtuse, seed appears thick and blocky.

B. secalinus, chess (pi. Ill, 53).

hhl). Palea longer than the grain, often a little shorter than

the lemma, broader at the top and narrowed abruptly

to a notched or obtuse apex, concavity shallow, smooth

or sometimes creased or wrinkled ; lemma much

broader than the grain above the middle, apex obtuse

or with shallow notch, midnerve evident to base,

lateral nerves often obscure in lower half, the margins involute in lower portion ; grain fiatter than in

B. secalinus.

B. commutatus, hairy chess (pi. Ill, 52).

CENCHRUS—SANDBUR

Genchrus paucißorus^ field sandbur (pi. Ill, 63) : The spikelets,

usually two in number, are enclosed in a spiny bur. The burs are not

commonly found in crop seeds, but the hulled grains may occur in

alfalfa and similar crops.

The hulled grains are light brown, broadly oval or oblong, with a

relatively large embryo area ; length 3 to 3% mm.

CHLORIS—FINGERGRASS

(PI. Ill, 58-60)

Spikelets of Ohloris are several-flowered, disarticulating above the

glumes. The lower floret is sessile and perfect, the upper florets
212 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

sterile. The sterile florets consist of empty lemmas, and if more

than one is developed the smaller ones are often enclosed in the lower,

producing an inflated, wedge-shaped rudiment. The entire spikelet,

mature fertile floret and attached sterile florets, is the unit usually

considered the seed. The pubescence on the fertile lemma and the

character of the sterile lemmas are important diagnostic features.

Seeds of four species are described. C, gayana^ Rhodes grass, is a

pasture plant of the Southern States. Three species may occur incidentally with crop seeds: C, virgata^ feather fingergrass, a native

species; O, divaricata^ slender chloris; and C, acicularis^ windmill

grass, occur in importations of Rhodes grass from Australia and may

in time become established here.

SEED KEY

A. Fertile lemma keeled, margins ciliate; a small groove between margin and

keel; rachilla bearing one to three obtusely pointed or wedge-shaped

sterile lemmas.

a. Keel of lemma without pubescence ; cilia on margins appressed below,

longer and spreading at the top ; basal hairs sparse, appressed ; color

yellowish straw; length (excl. of awn) 3 to 3i/^ mm., width approx.

1 mm. ; awn 2 to 5 mm Chloris gayana, Rhodes grass (pi. Ill, 60).

1). Keel of lemma densely pubescent, humped ; cilia on margins appressed

below, much longer and spreading at the top; basal hairs dense,

spreading; color dark brown; length (excl. of awn) 3 to 3% mm.,

width 1 mm. or more ; awn 6 to 10 mm. or longer.

G. virgata, feather fingergrass (not illus.).

B. Fertile lemma keeled, margins not ciliate ; not grooved between margin and

keel; rachilla about % the length of lemma, bearing a whitish, deeply

2-cleft sterile floret.

Keel of lemma without pubescence; minutely hispid in upper portion, apex

deeply >2-cleft ; color light to dark brown, whitish toward the top ; basal

hairs whitish, appressed or spreading; length (excl. of awn) 3 mm., width

% mm., awn 8 to 10 mm C. divaricata, slender chloris (pi. Ill, 58).

C. Fertile lemma flattened dorso-ventrally, with prominent cordlike midnerve

throughout entire length, terminating in long awn ; rachilla about %

the length of lemma, bearing a very narrow long-awned sterile floret.

Lemma glabrous or sparingly and minutely hispid at the top, apex minutely

cleft, the long narrow base with tuft of white spreading hairs at the callus ;

color light brown; length (excl. of awn) 6 mm., width % to % mm., awn

10 to 12 mm. or longer C. acicularis, windmill grass (pi. Ill, 59).

CORYNEPHORÜS

Corynephorus canescens^ club-awn grass (pi. Ill, 61) : The spikelets

are two-flowered, disarticulating above the glumes. The mature floret

or seed is about li/¿ mm. long or more; the lemma and palea are silvery,

thin and transparent, the callus and rachilla densely^ villous. The

awn, arising from near the base, is jointed about the middle, the joint

with a ring of short stiff hairs ; below the joint the awn is dark reddish

brown and finely striate, pale gray above the joint.

The seed occurs with imported crops, such as bentgrass.

CYNOSURUS—DOGTAIL

(PI. Ill, 64-65)

The panicle of Cynosums consists of two kinds of spikelets, sterile

and fertile. The fertile spikelets are two to three flowered, disarticu-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 213

lating above the glumes. The processed seed consists of the caryopsis with its lemma, palea, and rachilla segment.

Two species of Gynosurus are of interest: 0, cristatus^ crested dogtail, a perennial, sometimes used in grass mixtures for meadows or

found incidentally with crop seeds ; and C, echinatus^ an annual, sometimes occurring as a weed seed with crop seeds from the west coast.

The chief distinguishing features of seeds of the two species are

color, size, and length of awn.

SEED KEY

A. Seed sulphur yeHow; length (excl. of awn) 3% to 4 mm., width 1 mm. or

less ; awn approximately 1 mm. ; lance-shaped, with fine midnerve above

the middle ; lemma coarsely granular and finely hispid toward the top and

along margins ; rachilla with wide disc at the apex.

Cynosurus cristatus, crested dogtail (pi. Ill, 64).

B. Seed pale gray; length (excl. of awn) 5 to 7 mm., width li/4 to 1% mm.;

awn 10 to 15 mm. ; elliptic ; lemma finely hispid on upper half and along

margins, obscurely 5-nerved above the middle; rachilla threadlike, with

distinct disc at the apex G. echinatus, bristly dogtail (pi. Ill, 65).

. DACTYLIS

Bactylis glomemta^ orchard grass (pi. Ill, 66) : The lemma is

compressed laterally and curved to one side toward the top, ciliate on

the keel, lightly five-nerved, short-awned ; length, including the short

awn, 7 to 8 mm. ; grain soft.

DANTHONIA—OATGRASS

(PI. Ill, 67-68)

Danthonia spicata^ poverty oatgrass (pi. Ill, 67) : The lemma is

31/^ to 5 mm. long, sparsely villous except on the two-toothed summit;

palea is broad, flat, obtuse, reaching to the base of the awn.

Seeds produced from cleistogenes sometimes occur with crop seeds.

These seeds (pi. Ill, 68) are long and slender, the lemma tip not cleft,

the rachilla prolonged into a long bristle.

DESCHAMPSIA—HAIRGRASS

(PI. Ill, 69-70)

The spikelets of Deschampsia are two-flowered, disarticulating

above the glumes and between the florets. Two species are described,

D, caespitosa and D. ßexuosa. Both species may occur with crop seeds.

Deschampsia caespitosa^ tufted hairgrass (pi. Ill, 69) : The lemmas

are silvery, smooth, and semiglossy, length about 2^2 mm.; awn attached at the base, straight or semigeniculate ; basal hairs long and

spreading at the ends, shorter across the middle; palea about equal to

lemma, arched longitudinally, finely pubescent on the keels ; rachilla

about half the length of the lemma, pubescent with long, spreading

hairs.

Deschampsia ßexuosa^^ crinkled hairgrass (pi. Ill, 70) : The lemmas

are light brown, becoming lighter toward the tip, sparingly hirsute

on upper half, length about 4 mm. ; awn attached near the base, twisted

and geniculate ; basal hairs copious, long and spreading ; palea about

equal to lemma, flat, pubescent on the keels ; rachilla with a tuft of

long spreading hairs on either side, near the top.
214 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

DISTICHLIS—SALTGRASS

(PI. Ill, 71-72)

The hulled grains of two species of saltgrass may occur with crop

seeds: D, stricta is widely distributed throughout the western half

of the United States ; Z>. spicata is confined to coastal areas of the

Atlantic, Pacific, and Gulf coasts. The grains are a dull light brown,

roughly ovate in shape, with minute longitudinal wrinkles. Remnants

of style branches appear as two minute beaks or prongs at the top of

the grain. The character of these beaks is an important distinguishing feature.

D, stricta^ desert saltgrass (pi. Ill, 71) : The grains are 3 to 4 mm.

long and terminate in a long two-pronged beak. Occasional seeds

are longer and narrower than those shown in the illustration, and

the beak is correspondingly longer. When found in processed seed

the beak is often partially broken away, but even in this condition the

size of the seed and the remnant of the beak will usually distinguish it

from D, spicata.

Z>. spicata^ seashore saltgrass (pi. Ill, 72) : The grains are about

2 mm. long and terminate in two minute prongs at the apex, the apex

not prolonged into a definite beak.

ECHINOCHLOA

(PI. IV, 76-78)

The spikelet of Echinochloa is essentially as in Panicum^ but the

thin and papery second glume and sterile lemma are awned or awntipped, and bear scattered spinelike hairs. The size of the spikelets,

length of awn, and relative length of the second glume and sterile

lemma serve to distinguish the species.

Seed samples may contain a variable proportion of hulled seeds

(the caryopsis within its lemma and palea). The lemma and palea

are hard, smooth, and shining; plano-convex, the lemma so sharply

arched it is difficult to grasp with forceps. Size and shape are the

chief distinguishing features of the hulled seeds.

SEED KEY

A. Hulled seed 2 mm. long.

Broadly elliptic. Spikelet ; sterile lemma and second glume equal, shortpointed Echinochloa colonum, jungle rice (pi. IV, 76).

B. HuUed seed 2% to 3 mm. long.

Broadly elliptic. Spikelet ; sterile lemma long-awned, second glume acutepointed - E. crusgalU, barnyard grass (pi. IV, 77).

Broadly lance-shaped. Spikelet ; sterile lemma short-awned, second glume

short-pointed.

E, crusgalli var. frumentacea, Japanese millet (pi. IV. 78).

ELYMUS—WILD-RYE

(PI. IV, 81-84)

The spikelets of Elymus are two to six flowered, disarticulating

above the glumes and between the florets. In certain species the mature

florets are somewhat similar to Agropyron.

Six species are described. One species, Elymus canadensis^ including the improved variety Mandan wild-rye, is in commercial production. Three species are in limited production or experimental plant-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 215

ings : E, glaucus; E, junceus; and E. triticoides. Seeds of E. mrginicm

and E, riparius^ as well as the above-named species, may occur incidentally with crop seeds.

Elymus canademis^ Canada wild-rye, is a widely distributed, variable species, with several more or less intergrading botanical varieties.

The lemmas are mostly copiously hirsute, in some varieties sparingly

so or nearly glabrous. Completely glabrous lemmas appear to be

rather rare.

Elymus riparius^ riverbank wild-rye, is confined to the eastern half

of the United States, north of Arkansas, Kentucky, and North Carolina. The seeds of E. canadensis may be distinguished from this

species by the hirsute lemmas and longer paleas.

Elymus virginicus^ Virginia wild-rye, is also a widely distributed

and variable species, with several recognized varieties. The seeds

may be distinguished from E. canadensis and E, riparius by the short

awn and coarsely granular lemma.

SEED KEY

^4. Awn 20 to 30 mm. long or longer.

a. Awn straight ; palea markedly shorter than the lemma.

Lemma coarsely granular, sparingly hispid on the nerves above,

bifid, callus pubescent; length (excl. of awn) 11 to 12 mm.,

width l^A mm Elymus glaucus, blue wild-rye (pi. IV, 82).

Lemma scurfy and minutely hispid, lateral nerves oïten exserted

at the tip, callus short-pubescent; length (excl. of awn) 10 to

12 mm., width 1% mm.

E. riparius, riverbank wild-rye (not illus.).

Ö. Awn divergent and curved; palea equal to lemma or nearly so.

Lemma hirsute, not bifid or with exserted nerves, callus glabrous

or with short hairs at each end; length (excl. of awn) 10 to 12

mm., width 1% mm.

E. canadensis, Canada wild-rye (pi. IV, 81).

B. Awn less than 5 mm.

a. Lemma stife, glossy, smooth, or sparingly scabrous on midnerve at the

tip; callus smooth; length (excl. of awn) 8 to 9 mm., width 11/2 mm.

or more.

E. triticoides, beardless wild-rye (not illus.).

5. Lemma coarsely granular, sparingly scabrous, callus smooth; length

(excl. of awn) 8 to 9 mm., width 1^/^ mm. or more.

E. virginicus, Virginia wild-rye (pi. IV, 84).

c. Lemma scurfy, pubescent, callus smooth or sparingly pubescent ; length

(excl. of awn) 8 to 10 mm., width l^/^ mm. or more.

E. junceus, Russian wild-rye (pi. IV, 83).

ERAGROSTIS—LOVEGRASS

(PI. IV, 85-90)

The spikelets of lovegrass are several-flowered, disarticulating

above the glumes. Processed seed consists almost entirely of hulled

caryopses.

Seven species are described, only two of which are of recognized

agricultural value in this country^ Eragrostis curvula, weeping lovegrass, and E, trichodes^ sand lovegrass. The other species under consideration are either of experimental interest or as incidentals with

crop seeds.
216 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

SEED KEY

Á. Surface light brownish yellow, embryo area black ; smooth or faintly striate.

a. Length 1% to 2 mm., width 1 mm. or less; embryo area oblong, with a

distinct rim EragrosUs curvula, weeping lovegrass (pi. IV, 88).

&. Length 1 mm. or less, width % mm. ; embryo area obtusely triangular

or broadly oval, not distinctly rimmed.

E. leJimanniana, Lehman lovegrass (pi. IV, 89).

B. Surface and scar area light brown or dark reddish brown.

a. Ventral side with deep longitudinal cavity ; surface reticulated ; broadly

oblong.

aa. Length 1 to 1% mm., width 1 mm. or more ; reticulations faint.

E. trichodes, sand lovegrass (pi. IV, 90).

&Ö. Length i^ to % mm., width % mm. ; reticulations prominent.

E. capiUariSy lacegrass (pi. IV, 85).

&. Ventral side without longitudinal cavity.

aa. Surface finely striate ; narrowly oblong, length 1 mm. or more,

width % mm E. chloromelas, Boer lovegrass (pi. IV,

87).

1)1}. Surface faintly reticulated ; rotund, with a pointed base ; length

and width about equal, % to 1 mm.

E. ciUanensis, stinkgrass (pi. IV, 86).

cc. Surface neither striate nor reticulate; ventral side strongly

arched ; length 1 to 1% mm., width % mm.

E. tef, tefe (not illus.).

(£7. adyssinica).

FESTUCA 8—FINE-LEAVED FESCUES

(PI. IV, 95-96)

Seeds of the fine-leaved fescues are very similar, and because of the

large number of strains involved they present a serious problem in

identification.

Two species represent the cultivated forms: Festuca ovina^ sheep

fescue; and F, rubra^ red fescue, with its variety Chewings fescue

{F, rubra var. commutata). F, rubra has, in addition, several recognized strains such as lUahee, Eainier, and Prince Georges. F. capillata^ hair fescue, is not a cultivated crop in this country but occurs

incidentally with other crop seeds.

The principal weedy species found incidentally with crop seeds

are F. myuros^ rattail fescue; F. octo-flora^ sixweeks fescue; and F,

megalura^ foxtail fescue. Space does not permit showing all of these

species in the illustrations.

Seeds of the ovina-i'ubra group are too variable to permit accurate

identification of the individual seeds in all cases. However, when a

small sample is viewed it should, in most cases, be possible to identify

it as to kind by a combination of characters such as relative size,

length of awn, and character of lemma. With practice, it is often

possible to recognize bulk samples of the various strains of the rubra

group. .Two seed keys are presented, one key showing the distinguish-

* A more complete study of the species of fine-leaved fescues, with photographs

of seed drawings, may be obtained by purchase from the Grain Branch, Production and Marketing Administration, U. S. Department of Agriculture, Washington 25, D. (\
TESTING AGRICULTURAL AND VEGETABLE SEEDS 217

ing features of the different species, the other key showing bulk distinctions to be found in the ovina-ruhra group.

SEED KEY TO THE SPECIES

A. Length (excl. of awn) 9 to 10 times tlie width; awn twice the length of the

lemma or longer ; raehilla flat against the palea, apex in oblique position,

not expanded into a disc.

a. Edges of lemma with long ciliate hairs toward the top (except on primary florets) Festuoa megalura, foxtail fescue (not illus.).

&. Edges of lemma devoid of cilia ; width approx. i^ mm.

F, myuros, rattail fescue (pi. IV, 96).

B. Length (excl. of awn) less than 9 times the width; awn i/^ length of lemma

or less ; raehilla stands away from palea, apex in nearly horizontal position,

expanded into a disc.

a. Broadly elliptic; awnless or nearly so, occasionally with short awn.

Length (excl. of awn) approx. 3 mm., width 1 mm.

F. capillata, hair fescue (not illus.).

&. Narrowly elliptic, oblong or lanceolate ; awn % to % length of lemma

(exceptions in F. octoflora).

Length (excl. of awn) 4 to 4% mm., width % mm. or more ; lemma

sparingly scabrous toward the top and along margins, to almost

smooth ; awn sometimes shorter or longer than above.

F. octoflora, sixweeks fescue (not illus.)

Length (excl. of awn) 4 to 7 mm., width 1 to 1% mm. ; pubescence

on lemma variable F. ovina, sheep fescue (not illus.).

F. ruhra vars. and strains, red fescue (pi. IV, 95).

KEY TO THE BULK DISTINCTIONS OF SEEDS OF THE OVINA-RÜBRA

GROUP

<4. Length (excl. of awn) 4 to 5 mm., width 1 mm.

a. Lemmas mostly sparingly short-pubescent at the top, hairs appressed

or longer and spreading, occasionally short-pubescent along margins

at the base ; rachillas sparingly pubescent, hairs long and spreading,

or short-pubescent to almost smooth; awns mostly % the length of

the lemma, occasionally % or longer ; in some lots keels of palea inrolled, almost touching in upper % so seed appears long-pointed on

ventral side, other lots more open and flaring.

F, ovina, sheep fescue (not illus.).

&. Lemmas smooth, sparingly short-pubescent at top and on margins at

the base, or long-pubescent over entire surface ; rachillas smooth or

sparingly to copiously long-pubescent: awns % to i/^ the length of

lemma or longer F. ruhra, commercial red fescue (pi. IV, 95).

c. Lemmas smooth or minutely scabrous at top and on margins at the base ;

rachillas sparingly pubescent to almost smooth; awns 1/5 or less to

1/^ the length of the lemma.

F. rudra var. commutata, commercial Chewings fescue (not illus.).

d. Lemmas minutely and sparingly scabrous at top and along sides or almost smooth, occasionally with longer soft pubescence along the sides,

texture tends to be delicate and papery ; rachillas sparingly pubescent to smooth ; awns % the length of lemmas or less.

F. ruhra, Illahee strain (not illus.).

B. Length (excl. of awn) 6 to 7 mm., width 1 to l^^ mm.

a. Hairs on keels of paleas long, close-spaced; lemmas sparingly longpubescent along margins or almost smooth ; raehilla hairs few or

lacking ; awns % to % the length of the lemma.

F. ruhra, Rainier strain (not illus.).
218 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

FESTUCA 9—TALL FESCUE; MEADOW FESCUE

(PL IV, 93-94)

Two species of tall fescue are important agricultural crops : Festuca

elatior^ meadow fescue ; and F. arundinacea^ tall fescue, with two horticultural varieties, Alta fescue and Ky-31.

As pointed out in the seed key, seeds of meadow fescue and tall

fescue are readily distinguished by their shape, together with the texture and pubescence of the lemmas. Distinguishing the seeds of tall

fescue and its varieties Alta fescue and Ky-31 fescue is more difficult.

The distinctions between them are fine, and it is possible that these

may not be apparent in all seed lots.

SEED KEY

A. Lemma short-pointed, awnless, glabrous and smooth, or minutely and sparingly scabrous at the tip F, elatior, meadow fescue (pi. IV, 93).

B. Lemma long-pointed, awned, or rarely awnless, coarsely granular, scabrous

on nerves, especially toward top, and sparingly between nerves and along

the margins F. arundinacea, tall fescue (pi. IV, 94).

var. Alta (notillus.).

var. Ky-31 (not illus.).

HORDEUM—BARLEY

(PL V, 104-108)

The spikelets of Hordemn are one-ñowered, usually w^ith three spikelets at each joint of the rachis. The unit of three spikelets consists

of a middle fertile floret, Avhich is usually sessile, and two pedicellate

lateral, infertile florets (except in H, vulgäre). The character of the

infertile florets and the attached glumes are important diagnostic

features. In processed seed the clusters may be broken apart, only

the matured fertile florets remaining. Without the attached glunies

and sterile florets it is not always possible to identify the seed with

certainty.

Five species are illustrated and described. One species, Hordeum

vulgäre^ is an important cultivated crop. Four species may occur as

weeds with such crops as alfalfa and orchard grass: H, irachyantherum {H, nodosum) ; H, juhatum; H, pusillum; and H. leporinum

(H, murinum),

There are many varieties of cultivated barley. In some varieties

the grain is naked, but these are in rather limited cultivation. Most

varieties have persisting hulls (lemma and palea), the chief distinguishing features being length and pubescence of awn and rachilla, and

the presence or absence of transverse wrinkles in the hull. The

identification of varieties by seed character is not a part of this study.

Seeds of some varieties are described by Àberg and Wiebe (i).

SEED KEY

A. Fertile floret broadly elliptic, thick ; length to tip of palea 10 to 12 mm., width

4 mm., awn about 15 mm. ; lemma and palea thick and stiff, smooth or with

fine transverse wrinkles; rachilla threadlike; in edge view, ventral side

convex, dorsal side nearly straight-- Hordeum vulgäre, barley (pi. V, 104).

^ A more complete study of the species of tall fescues and ryegrass, with photographic plates of seed drawings, may be obtained by purchase from the Grain

Branch, Production and Marketing Administration, U. S. Department of Agriculture, Washington 25, D. C.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 219

B. Fertile floret narrowly elliptic or lanceolate, flattened ; length to tip of palea

6 to 8 or 9 mm., width 1% to 2 him., awned ; lemma stiff, granular, minutely

and sparingly hispid at the top ; midnerve faint or obscure ; rachilla threadlike, 1/^ to % the length of the lemma.

a. Fertile floret sessile, sterile florets pedicellate; fertile floret disarticulates by partial abscission.

aa. Glumes all bristlelike ; keels of palea inturned, flattened, close

together and nearly parallel.

aaa. Palea with a fine longitudinal fold down the middle ;

awn 18 to 20 mm. long.

H. judatum, foxtail barley (pi. V, 107).

hi)}). Palea without longitudinal fold down the middle; awn

5 to 6 mm. long.

H, hrachyantherurn, meadow barley (pi. V, 106).

&&. Inner glumes expanded below and tapering into long awns, the

two outer glumes bristlelike ; keels of palea not inturned and

flattened, spread apart about midway; grain thicker than

juhatum and hrachyantherum (nodosum) ; awn 5 to 6 mm.

long . H. pusillum, little barley (pi. V. 105).

h. Fertile and sterile florets pedicellate; inner glumes slender and ciliate

on the margins, the two outer glumes bristlelike ; awn of fertile floret

about 35 mm. long ; fertile floret disarticulates hj fracture ; keels of

palea inturned, forming two thick longitudinal rolls, the margins

almost touching- H. leporinum (H. murinum), wall barley (pi. V, 108).

LEPTOLOMA

Lepfoloma cognatmn^ fall witchgrass (pi. V, 109) : The first glume

is minute, the second glume and sterile lemma as long as the fertile

lemma ; pale straw color, thin and papery, with fine appressed hairs

between the prominent nerves, and longer hairs atthe margins. When

found incidentally with crop seed the hairs may be almost entirely

rubbed off, as shown in upper right of the illustration. The unit considered the seed is usually the caryopsis within the lemma and palea,

with or without the glumes or only portions of them persisting.

The lemma is approximately 2^ to 2% mm. long, % mm. wide;

hardened, minutely tubercled and finely striate lengthwise; dark

brown, the margins lighter and thinner, overlapping the palea at the

top. The palea is similar to the lemma in surface and texture.

The seed may occur with alfalfa and similar crops from the Great

Plains.

LOLIUM—RYEGRASS

(PL V. 110-113)

Seeds of ryegrass and the tall fescues (pi. IV, 93-94) are very

similar but they are readily distinguished by the character of the

rachilla, shape of the seed, and to some extent, the position of the

hairs on the keels of the palea.

The rachilla of ryegrass is flattened, sometimes with an angle down

the middle, the apex, scarcely or not at all expanded, lies flat against

the palea. In the tall fescues the rachilla is cylindrical, the apex,

expanded into a disk, tends to stand away from the palea.

Three species of Lolium are in cultivation :Z. perenne^ perennial

ryegrass ; Z. multiflorum^ Italian ryegrass ; and Z. rigidufm^ Wimmera

ryegrass. Westernwolth, a variety of Z. multiftoTum^ and Wimmera

ryegrasses are in experimental plantings. Two species occur as weeds

957116—52 15
220 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT, OF AGRICULTURE

in cultivated fields, Z. tenmdentum^ darnel, and the more recently

introduced Z. persicum^ Persian ryegrass.

Seeds of the two weedy species are readily recognized. In the cultivated species it is usually possible to distinguish the seed in bulk but

individual seeds are more difficult to identify, especially if the seed

has been severely milled.

SEED KEY

A. Seed narrowly oblong; not markedly thickened through the middle; palea

not transversely wrinkled.

a. Lemma awnless, or when present awn short and frail.

Length approximately 6 mm.

Lolium perenne, perennial ryegrass (pi. V, 110).

Length 7 to 9 mm. L. rigiéum, Wimmera ryegrass (not illus.).

&. Lemma awned, occasional seed awnless.

Length, exclusive of awn, approximately 6^/^ to 7 mm.

L. multi/lorum, Italian ryegrass (pi. V, 111).

L. multifiorum var. Westernwolth (not illus.).

Length, exclusive of awn, approximately 8 to 10 mm,

L. persicum, Persian ryegrass (pi. V, 112).

B. Seed broadly elliptic ; markedly thickened through the middle ; palea transversely wrinkled.

Length, exclusive of awn, approximately 7 mm.

L. temulentum, darnel (pi. V, 113).

NASSELLA

Nassella trichofoma, no common name (pi. V, 116) : The laterally

compressed, roughly triangular caryopsis is completely enclosed in a

hardened, tuberculate lemma, the overlapping edges of which completely obscure the membranous palea (see view at right in illustration) ; yellowish or brownish straw color.

The lenuna, exclusive of awn, is 2 to 2^4 ïïiïïi- long and approximately 1 mm. wide at widest point; awn about 30 mm. long, straight or

flexuous, twisted ; basal hairs silvery white, copious, appressed, 1/3 to

% the length of the lemma. The palea is membranous, about % the

length of the caryopsis. View at lower left in the illustration shows

the long, acuminate, awn-tipped glumes.

This seed is a characteristic impurity in importations of oats from

Argentina.

PANICUM 10—PANICUM

(PL VI, 121-138)

The spikelet of Panicwni consists of two thin papery glumes, a sterile

floret, and a fertile floret. The first glume is usually much reduced ;

the second glume and sterile lemma are similar in texture but longer.

The lemma and palea of the fertile floret are hard and, in many

species, smooth and shiny ; in other species roughened by vertical rows

of minute tubercles. In some species the tubercles may be fused to

form transverse ridges on the lemma. The character of the lemma

and seed scar are important diagnostic features.

" A more complete study of Panicwm, with photographic plates of seed drawings, may be obtained by purchase from the Grain Branch, Production and

Marketing Administration, U. S. Department of Agriculture, Washington 25,

D. a
TESTING AGRICULTURAL AND VEGETABLE SEEDS 221

SEED KEY

A. Lemma roughened, dull.

a Seeds IVo to 2 mm. long; narrowly elliptic, with coarse transverse

ridges-!! -P. maximum, Guinea grass (pi. VI, 132).

&. Seeds 2V2 to 4 mm. long.

aa. Broadly ohovate.

21/^ mm. long, obscurely roughened, both faces strongly convex ; olive green to darle yellowish green.

P. drachyanfhum, no common name (pi. VI, 124).

&Ö. Broadly elliptic.

2% mm. long ; both faces strongly convex, with coarse transverse ridges; dark straw color to light brown.

P. fasciculatum, browntop panicum (pi. VI, 128).

3 mm. long ; one face convex, with coarse transverse ridges ;

ivory to pale golden yellow

P. ramosum, browntop millet (pi. VI, 136).

CO. Narrowly elliptic.

2% to 3 mm. long, minutely roughened and striate lengthwise P. purpurascens, Para grass (pi. VI, 135).

dd. Lance-shaped.

Sy2 to 4 mm. long, with coarse transverse ridges and fine

vertical lines P. texanum, Texas millet (pi. VI, 137).

B. Lemma smooth, glossy.

a: Seeds 1 to 1% mm. long.

aa. Narrowly elliptic.

iy2 mm. long ; scar oval, inconspicuous ; dark yellow streaked

with olive green P. capillare, witchgrass (pi. VI, 125).

&&. Narrowly oblong or lance-shaped.

1% mm. long; scar broadly crescent-shaped; dark yellow

streaked with olive.

P. capillare var. occidentale, barbed witchgrass (pi. VI,

126).

1% mm. long; scar broadly triangular; flat; olive green or

dark yellowish green.

P. dichotomiflorum, fall panicum (pi. VI, 127).

CG. Broadly elliptic.

aaa. 1% mm. long; scar oval, callus narrow (vertically) ;

light straw color with greenish tinge.

P. anceps, beaked panicgrass (pi. VI, 121).

Ö&&. 11/4 to 1% mm. long; scar broadly triangular; callus

wide (vertically), pointed; yellowish straw color.

P. huachucae, hairy panicgrass (pi. VI, 131).

CCG. 1% to 2 mm. long; scar crescent-shaped, large, prominent ; olive green or dark yellowish green.

Winglike points of scar approximately % mm. long.

P. hillmani, Hillman panicgrass (pi. VI, 130).

Winglike points of scar approximately % mm. long.

P. dergii, Berg's panicgrass (pi. VI, 123).

ddd. IV^ mm. long ; scar lens-shaped with a minute knoblike

projection at base ; dull yellow streaked with olive

green.

P. gattingeri, Gattinger's witchgrass (pi. VI, 129).

1). Seeds 2 to 3 mm. long.

aa. Narrowly elliptic.

2 mm. long ; straw color splashed with brown ; palea longer

than lemma.

P. antidotale, blue panicgrass (pi. VI, 122).
222 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

th. Angularly elliptic.

21/^ to 3 mm. long ; pale straw color, sometimes streaked with

dark gray P. virgatum, switchgrass (pi. VI, 138).

CO. Obovate or broadly elliptic.

3 mm. long; callus wide (vertically), pointed.

P. ohtusum, vine-mesquite (pi. VI, 1S4).

dd. Rounded and turgid or broadly elliptic and flatter.

3 mm. long; scar crescent-shaped; colors, various.

P. miliaceum, proso ; broomcorn millet (pi. VI, 133).

PASPALUM—PASPALUM

(PI. VII, 139-148)

The one-flowered spikelets of Paspalum are planoconvex, the first

glume usually wanting, second glume and sterile lemma about equal,

thin and papery; the fertile lemma stiff and hard (except in

P, malacophyllum).

Ten species are described. Two of the species, P, dilatatum^ Dallis

grass, and P. notatum^ Bahia grass, are in cultivation as pasture

grasses in the Southern States. Two species are in more limited use

for pasture : P, urviUei^ Vasey grass, and P. malacophyllum^ ribbed

paspalum. P. distichimi, knotgrass, has some value as a soil binder.

Seeds of these and other species may occur incidentally with Southern

crop seeds.

SEED KEY

A. Papery glumes (second glume and sterile lemma) persisting (partially in

doscianum) ; fertile lemma stiff and hard, yellowish, finely roughened.

a. Glumes long-pubescent, especially along the margins; broadly lanceshaped, only slightly convex on the back.

Light yellowish-brown, 5-nerved; length 3 to 3% mm., width

2 to 2% mm Paspalum dilatatum, Dallis grass (pi. VII, 140).

Reddish-brown, 3-nerved ; length 2% to 2% mm., width 1% mm.

P. urvillei, Vasey grass (pi. VII, 148).

b. Glumes sparingly short-pubescent over entire surface ; length 2i/^ to

3^ mm., width 1^/4 to 1% mm. ; elliptic to lance-shaped.

P. distichum, knotgrass (pi. VII, 141).

o. Glumes without pubescence or nearly so ; strongly convex on the back.

aa. Length 4 mm. or more ; oval ; width 3 mm. ; glumes grayish,

dull, 5-nerved ; fertile lemma light brown, roughened.

P. fioridanum, Florida paspalum (pi. VII, 142).

hb. Length less than 3 mm. ; fertile lemma finely roughened.

aaa. Glumes dull reddish brown, 5-nerved; fertile lemma

dark reddish brown.

Elliptic; sterile lemma (plane surface) with 4 distinct,

transverse ridges just inside the raised margins;

length 21/2 to 2% mm., width 1% mm.

P. pUcatulum, brownseed paspalum (pi. VII, 146).

Oval or obovate; sterile lemma not ridged; length

2 to 2% mm., width 2 mm. or more.

P. dosoianum, bull paspalum (pi. VII, 139).

hbl). Glumes dull grayish brown, oval to orbicular; fertile

lemma yellowish.

Length 2^^ to 2% mm., width 2^^ mm. ; 3 nerves distinct on the back.

P. la&i}e, field paspalum (pi. VII, 143).

Length 1^2 to 2 mm., width l^/^ mm. ; midnerve on the

back faint, lateral nerves obscure or lacking.

P. setaceum, slender paspalum (pi. VII, 147).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 223

B. Papery glumes not persisting ; fertile lemma strongly convex on the back.

a. Fertile lemma oval, stiff, smooth and glossy, often slightly wrinkled

transversely, 3-nerved ; length 3 to 31/2 mm., width 2% to 3 mm.

P. notatum, Bahia grass (pi. VII, 145).

&. Fertile lemma not stiff and glossy ; narrowly elliptic, distinctly 5-nerved,

dull, granular ; length 2 mm., width 1 mm.

P. malacophyllum, ribbed paspalum (pi. VII, 144).

PENNISETXJM

(PI. VII, 149-150)

The panicle of Pennisetum is cylindric, dense, and spikelike. The

large caryopses burst through the lemma and palea, falling free from

the panicle. Processed seed consists almost entirely of hulled

caryopses.

Two species are of interest in this country : P. glaucum^ pearl millet;

and P, purpurevm^ Napier grass. These are in limited use for forage

in the extreme South. Shape and thickness are the only features

distinguishing the caryopses of the two species.

SEED KEY

A. Obovate or top-shaped; in edge view, dorsal edge is straight, ventral edge

convex ; length 3 to ZV^2 mm., width 2 to 21/2 mm.

P. glaucum, pearl millet (pi. VII, 149).

B. Shape roughly oblong, flattened dorsoventrally ; in edge view, both dorsal

and ventral edges straight and nearly parallel; length 4 mm., width 2 mm.

P. purpureum, Napier grass (pi. VII, 150).

PHALARIS—CANARY GRASS

(PI. VII, 151-156)

The spikelet of canary grass consists of one terminal perfect floret

and two sterile lemmas below it (rarely only one or none). The sterile

lemmas are reduced and closely appressed to the fertile floret, the entire spikelet disarticulating above the glumes. The seed of commerce

consists of the one fertile floret with its sterile lemmas attached just

above the callus. The lemma of the fertile floret is stiff, laterally compressed and more or less enclosing the palea.

Seven species are described. Three of these are cultivated crops :

P. canariensis^ canary grass ; P. arundinacea^ reed canary grass ; and

P. tuberosa var. stenoptera^ Harding grass. Seeds of the other species

occur incidentally with crop seeds.

SEED KEY

A. Sterile lemmas 2, equal or subequal.

a. Fertile lemma, 5 to 6 mm. long, 2% mm. wide.

Elliptic ; buff-colored, glossy, glabrous or nearly so, ciliate on margins near the top; sterile lemmas glabrous, spreading, usually

lacking in threshed seed.

Phalaris canariensis, canary grass (pi. VII, 155).

1). Fertile lemma, length 4 mm. or less, width 1 to iy2 mm. ; light to dark

grayish brown, glossy.

aa. Linear-lanceolate ; length 3 to 3% mm., width 1 mm. ; fertile

lemma very sparingly pubescent and ciliate on the margins

toward the top; nerves distinct on the dark gray-brown surface ; sterile lemmas long-pubescent along their margins.

P. arundinacea, reed canary grass (pi. VII, 152).
224 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

&Ö. Ovate or ovate-lanceolate ; length 2% to 3 mm., width IVé, mm. ;

fertile lemma sparingly pubescent tovi^ard the top, nerves

obscure; sterile lemmas glabrous.

P. augusta, timothy canary grass, (pi. VII, 151).

CO. Ovate, tapering abruptly to an awl-shaped apex ; length 2^^ to 3

mm., width 1% mm. ; fertile lemma copiously long-pubescent

over entire surface, nerves obscure ; sterile lemmas sparingly pubescent along the sides.

P. caroUniana, Carolina canary grass (not illus.).

B, Sterile lemma 1 ; second lemma, if present, so reduced it appears to be lacking ; fertile lemma glossy, yellowish to grayish brown ; nerves distinct

whitish lines.

a. Fertile lemma ovate-lanceolate ; pubescent on upper half ; length 4

mm., width li/^ to 1% mm. ; sterile lemma glabrous, second sterile

lemma much reduced or lacking.

P, tuberosa var. stenoptera, Harding grass (pi. VII, 154).

'b. Fertile lemma ovate; copiously pubescent on upper half; length 3 to

3V2 mm., width 1^ to 1% mm. ; sterile lemma glabrous.

P. minor, little canary grass (pi. VII, 153).

G. Sterile lemmas lacking.

Fertile lemma elliptic to lance-shaped ; glabrous, glossy, pale gray, often

tipped with yellow at top and base; length 3I/2 to 4 mm., width IV2

to 1% mm P. paradoxa, hood canary grass (pi. VII, 156).

POA "—BLUEGRASS

(PI. VIII, 159-164; pi. IX, 165-170; pi. X, 171)

Seeds of Poa are characterized by their small size and five-nerved

lemmas, keeled along the heavy midnerve and often finely pubescent,

with long weblike hairs at the base in most of the species. The hard,

dark brown caryopsis is strongly compressed laterally, with a blunt

keel on the back above the embryo and a more or less pronounced

groove on the opposite side. The grain is usually thickest through

the middle, or slightly below, and pointed at both ends. There is a

tendency for it to adhere to the palea so that free grains do not

commonly occur except in severely milled samples.

The back of the lemma is keeled along its entire length in most

species. The keel may be strongly arched longitudinally as in P,

trivialis^ or nearly straight as in P. pratensis^ for example. The

texture of the lemma and the presence or absence of pubescence are

important diagnostic features. Because of the fragile nature of the

pubescence and of the lemma itself, seeds that have been processed

may be badly rubbed or torn. Commercial lots of P. fvatensis and

P, arachnifera are familiar examples of this condition. In such cases

a careful examination under a magnification of 40 X to 60 X is necessary to see the evidence of these structures. The apex of the lemma is

characteristic in many species, but this in itself is not always conclusive. Florets in the upper part of a spikelet tend to be more slender

and pointed than the basal florets. Thus, in a species that predominantly has a broad, rounded apex some seeds with pointed lemmas may

be present.

The palea, usually slightly shorter than the lemma, is smooth in

some species and pubescent in others. As in other grasses, the margins

^^A more complete study of Poa, with photographic plates of seed drawings,

may be obtained by purchase from the Grain Branch, Production and Marketing

Administration, IJ. S. Department of Agriculture, Washington 25, D. C.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 225

of the palea fold over the grain along the two longitudinal nerves.

These nerves, known as keels, are fringed with minute hairs. The

character of these hairs, and in some cases the type of notch at the

apex of the palea, furnish reliable distinguishing features. (See

pi. X, 171.)

The rachilla is slender with parallel sides, the apex expanded into

a disc. In some species the rachilla is typically elongated. The

presence or absence of pubescence on the rachilla is an important

diagnostic feature in certain species.

In a spikelet the basil web is neatly folded against the base of the

lemma of each floret. The hairs may be characteristically long and

copious or few, or entirely lacking in certain species. After the floret

has been removed from the spikelet the web usually appears as a long

matted tuft of fine hairs. These delicate hairs are sometimes completely rubbed off in the process of cleaning and threshing. In the

illustrations the first view in all figures shows an unrubbed seed as

removed from a plant specimen. Other views for the most part show

the seed as it appears when rubbed from the panicle or as it would

appear in commercial seed lots.

In some cases there is not a wide divergence between species in

size, shape, or character of rachilla so that the lemma and palea must

be relied on to furnish the principal clues for identification. Where

fine distinctions such as these are involved, it is difßcult to find descriptive terms that will convey the desired picture to the reader. With

practice, however, these distinctions become readily apparent. Attention is directed to three species having seed that is sometimes difficult

to distinguish: P, juncifolia (not illustrated); P, ampia; and P.

nevadensis. The chief distinctions may be found in the character

of the pubescence and in the texture of the lemma. These differences

may be so slight that some seeds are not always distinct. In occasional

plant specimens of these three species the distinguishing features

are not clearly evident and the question can be raised as to the possibility of intergrading between the species.

SEED KEY

A, Lemma without pubescence, or only very sparingly pubescent on nerves

toward the base (exceptions in P. pratensis.)

a. Lemma smooth or very finely granular ; unrubbed seed webbed at the

base.

aa. Apex folded ; intermediate nerves distinct to the base.

aaa. Hairs on keels of palea coarse, short, wide-spaced, do

not extend to tip of palea (pi. X, 171) ; lemma 2i/^

to 3 mm. long.

P. pratensis, Kentucky bluegrass (pi. IX, 169).

ÖÖ&. Hairs on keels of palea short, fine, close-spaced, extend

to tip of palea (pi. X, 171) ; lemma 2% to 3 mm.

long; basal web scant.

P. trivialis, rough bluegrass (pi. IX, 170).

dd. Apex flares out; intermediate nerves obscure or lacking on

lower half.

Hairs on keels of palea short, fine, close-spaced, extend to the

tip (pi. X, 171) ; lemma 2% mm. long; basal web short,

scant, may appear to be lacking.

P. compressa, Canada bluegrass (pi. VIII, 164).
226 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

&. Lemma coarsely granular (grates on forceps), or scaberulous, no basal

web,

aa. Apex obtuse and flaring, sometimes acuminate; intermediate

nerves obscure.

aaa. Rachilla finely pubescent or granular; lemma mostly

obtuse, finely pubescent all over, 4 to 5 mm. long.

P. juncifoUa, alkali bluegrass (pi. X, 171i),

Ml). Rachilla smooth or finely granular ; lemma mostly acutepointed, sparingly pubescent on upper portion and

on nerves, 4 to 5 mm. long.

P. ampia, big bluegrass (pi. VIII, 160).

M. Apex acute to acuminate; intermediate nerves obscure or

lacking.

aaa. Rachilla pubescent; lemma 5 to 6 mm. long.

P. cusiokii, Cusick bluegrass (pi. X, 171n).

&Ö&. Rachilla smooth ; lemma 4 to 5 mm. long.

P. nevadensiSj Nevada bluegrass (pi. IX, 167).

B. Lemma pubescent.

a. Pubescence confined to nerves ; webbed at base except in annua, longiligula, and fendleriana.

aa. Pubescence on lower half, dense, long and matted, longer to

ward base.

Hairs on keels of palea fine, wide-spaced, becoming long

on lower half (pi. X, 171) ; apex of palea deep V-notched;

web very' long ; lemma 5 to 6% mm. long.

P. araehnifera, Texas bluegrass (pi. VIII, 161).

Hairs on keel of palea coarse, short, wide-spaced, do not

extend to tip of palea as in pi. X, 171a ; basal web shorter ;

lemma 2% to 3 mm. long.

Poa pratensis, Merion bluegrass (not illus.).

hh. Pubescence on lower half, long, silky (well above middle of

keel in annua and glaucifoUa).

aaa. Hairs on keels of palea fine, close-spaced, extend to

tip (pi. X, 171) ; basal web long, scant.

Rachilla pubescent; lemma 3 to SVi nim. long,

acuminate.

P. nemoralis, wood bluegrass (pi. IX, 166).

Rachilla smooth or finely granular ; lemma 2y2 to 31/2

mm. long, obtuse.

P. glauoifolia, no common name (pi. X, 171o).

hbh. Hairs on keels of palea long and dense, do not extend

to tip (pi. X, 171) ; no basal web.

Rachilla smooth; lemma 2V2 to 3 mm. long.

P. annua, annual bluegrass (pi. VIII, 159).

ccc. Hairs on keels of palea short, blunt, close-spaced, extend

to tip (pi. X, 171) ; basal web long, scant.

Rachilla coarsely granular to sparingly scabrous;

lemma 3 to 3% mm. long, finely granular.

P. interior, inland bluegrass (pi. IX, 165).

ddd. Hairs on keels of palea dense, uneven, long below,

becoming shorter and wide-spaced toward the top,

do not extend to tip (pi. X, 171) ; no basal web.

Rachilla pubescent, hairs long and bristly ; lemma 41/2

to 5 mm. long, acute to acuminate, scaberulous.

P. longiUgula, long-tongue mutton grass (pi. X, 171g).

Rachilla sparingly pubescent, hairs stiff and spreading but shorter than above ; lemma 4 mm. long, obtuse,

finely to coarsely granular.

P. fendleriana, mutton grass (pi. X, 171r).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 227

eee. Hairs on keels of palea short, coarse, wide-spaced, do

not extend to tip (pi. X, 171) ; basal web long, copious.

Rachilla smooth ; lemma 21/2 to 3 mm. long.

P. pratensis, Kentucky bluegrass (pi. IX, 169).

cc. Pubescence on lower half, sparse and shorter; basal web long,

scant.

Hairs on keels of palea short, fine, close-spaced, extend to

tip (pL X, 171).

Rachilla smooth ; lemma 2 to 2^^ mm. long.

P. palustris, fowl bluegrass (pi. IX, 168).

&. Pubescence not confined to nerves; no distinct basal web {hulhosa

excepted).

aa. Pubescence on lower half of nerves dense, long and lax, sparingly

hairy between nerves and on margins.

Lemma 3 to 3^/^ mm. long, obtuse; hairs on keels of palea

long on lower half, short above, extend to tip ; apex finely

notched (pi. X, 171) ; hairs at callus.

P. arida, plains bluegrass (pL VIII, 162).

ÖÖ. Sparingly pubescent on lower half, hairs long and lax, mostly

confined to keel and marginal nerves; no basal web; hairs

at callus.

aaa. Lemma acute-pointed, broad at base; narrow hyaline

margins above middle.

Hairs on keels of palea short, close-spaced, extend to

tip of finely notched apex (pi. X, 171) ; rachilla

pubescent, sometimes only granular; lemma 4 to

5 mm. long.

P. secunda, Sandberg bluegrass (X, 171/).

G. Florets mostly converted into flask-shaped, purple-colored bulblets.

P. bulbosa, bulbous bluegrass (pi. VIII, 163).

SETARIA—MILLET ; BRISTLEGRASS

(PI. X, 172-179 ; pi. XI, 180-183)

The spikelet of Setaria^ as in Panicum^ consists of a thin and papery

much reduced first glume, a longer second glume and sterile lemma

of like texture, and a fertile floret with hardened lemma and palea.

It is subtended by an involucre of one to several bristles. The spikelet falls free from the bristles so that these seldom appear in the harvested seed. The caryopsis enclosed in the hardened lemma and palea

is popularly considered the seed. Hulled caryopses are found occasionally in processed seed.

Seeds of certain species of Setaria are quite similar in appearance.

These may be segregated into three type groups :

1. Setaria viridis; S, vertioillata.

2. S, geniculata; S. faberi; S, lutescens,

3. S, itálica^ the foxtail millets.

Special attention should be directed to the distinguishing features

of the species within each of these groups. It will be observed that

seed shape is the chief point of distinction in group (1). The species

in group (2) may be distinguished by size, shape, and the position of

the margins of the lemma in relation to the keels of the palea. The

cultivated millets in group (3) are distinguished primarily on the

character of the surface of the lemma which is either minutely tuberculate or finely undulate.

Setaria itálica^ foxtail millet (pi. XI, 180-183) : The horticultural

varieties of foxtail millet in cultivation in this country fall into two
228 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

general groups: (1) German millet; and (2) Common millet. The

term "golden millet" has been used for both of these forms, and

since it has no specific meaning its use is confusing and should be

discontinued. Commercial seed lots are often mixtures of the two

forms, the mixture probably due in large measure to hybridization.

No means were found whereby seeds of hybrids could be distinguished.

Seeds of the millets are characterized by a waxy or oleaginous surface that is finely roughened by minute tubercles or faint undulations.

From an examination of herbarium material it appears that the character of the seed surface (lemma and palea) is constant and, as will

be pointed out, may be considered the principal feature distinguishing

the German and Common millet groups. The surface details may be

recognized under a hand lens, but a binocular microscope with a magnification of about 20 or higher is desirable for an accurate determination.

Seed shape is useful in making bulk determinations, but certain

elliptic forms are common to both groups so that shape cannot be

considered a constant character for the identification of an individual

seed. Seed color varies to a certain extent as pointed out in the

seed key. The glumes when present are helpful in making a diagnosis. As shown in the illustrations, the internode between the

first and second glumes is noticeably longer in German millet than in

Common millet. In this respect also, some intergrading may be found.

Hulled grains may be present in commercial seed samples. The grains

(not illus.) are broadly elliptic or rounded, thick, creamy white or

yellowish. The larger size and yellowish color ^ distinguish them

from the flatter, grayish-green caryopses of S, viridis and S, lutescens,

which are common impurities in millet samples.

The illustrations show the usual types of seed that may be found

in any one panicle of the kind under consideration. In some cases, in

order to show the detail of seed surface, it was necessary to sacrifice

the degree of convexity of the more turgid seeds. This detail is shown

more clearly in the edge views of the seeds.

SEED KEY

A. Seeds 2 to 2% mm. long.

a. Lemma smooth, glossy.

Broadly elliptic or rounded.

Setaria magna, giant bristlegrass (pi. X, 177).

Ö. Lemma finely roughened with vertical lines of minute tubercles and

irregular transverse ridges.

Narrowly elliptic.

Apex obtuse; greenish yellow or light brown mottled with

darker brown 8. viridis, green foxtail (pi. X, 179).

Apex short-pointed ; greenish yellow to dark brown.

S. verticillata, bur bristlegrass (pi. X, 178).

Broadly elliptic.

Apex pointed, terminating in a stout awl-point.

B. macrostachya, plains bristlegrass (pi. X, 176).

e. Lemma roughened with coarse transverse ridges.

Narrowly elliptic.

Apex short-pointed, 3-pronged ; ridges close-spaced ; greenish

yellow to dull brown.

<S. geniculata, knotroot bristlegrass (pi. X, 173).

Lance-shaped.

Apex long-pointed ; fine vertical lines, ridges less coarse than

in geniculata; color light cream or yellow.

S. grisehachii, Grisebach bristlegrass (pi. X, 174).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 229

B. Seeds 21/2 to 2% mm. long.

a. Lemma finely roughened S. itálica, foxtail millet (pi. XI, 180-183).

aa. Vertical lines of minute tubercles forming irregular transverse

ridges.

Rounded and turgid or broadly elliptic and flatter.

Pale straw color to golden yellow.

Var. German millet (pi. XI, 182).

Grayish white or yellowish.

Var. White Wonder millet (pi. XI, 183).

ÖÖ. Minute transverse undulations, not evidently tuberculate.

aaa. Narrowly to broadly elliptic.

Pale golden yellow. Var. Common millet (pi. XI, 180).

Orange to golden yellow.

Var. Siberian millet (not illus).

Uniform orange color Var. Kursk millet (not illus).

Yellowish straw color, light brown mottled with dark

brown, or dark brown.

Var. Hungarian millet (pi. XI, 181).

Ö&&. Lance-shape to narrowly elliptic.

Golden yellow Var. Goldmine millet (not illus.).

Ö. Lemma roughened with coarse transverse ridges.

aa. Broadly elliptic.

Ridges sharply defined, wide-spaced, with distinct smooth

areas between ; greenish, golden yellow, or dark brown.

8. lutescens, yellow foxtail (pi. X, 175).

1)J). Broadly to narrowly elliptic.

Ridges close-spaced, irregular; greenish yellow to dark

brown ;Sf. faheri, giant foxtail (pi. X, 172).

SORGHUM

(PI. XI, 185-194)

The spikelets are borne in pairs on a jointed rachis, one perfect

and sessile, the other sterile or staminate and pedicellate, the fertile

spikelet falling with the joint of the rachis and attached sterile pedicellate spikelet.

The mature, fertile floret consists of a pair of hardened glumes

enclosing a thin and translucent lemma and palea. The color of the

two glumes and the presence or absence of pubescence may vary with

the variety. The glumes may be persistent and fit smoothly on the

grain, as in Sudan grass and Johnson grass, or the glumes may be loose,

tending to spread apart from the grain as in many of the sorghums.

In certain varieties of sorghum the globose grain is much longer than

the loose glumes and the grains become almost completely hulled in

processing. Depending somewhat on the variety, the seed in commerce may be in the hulls, or completely hulled.

Sudan grass and Johnson grass (pi. XI, 185-186) : Three varieties

of Sudan grass are in cultivation at the present time : Common Sudan

(shown in the illustration); Tift Sudan; and Sweet Sudan. The

glumes of Sweet Sudan are sienna or reddish brown in color; those

of Common and Tift Sudan are mostly light straw color and do not

appear to be distinguishable.

Seeds of Sudan grass and the closely related Johnson grass may

be distinguished by the size, shape, and color of the glumes, and the

character of the attached rachis segment and pedicel.

Sorghum-Sudan hybrids (pi. XI, 187) : Certain seeds of sorghumSudan hybrids may be recognized by their shape and larger size, as
230 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

shown in the illustration. Because of the larger size, the seeds in

the illustration are not drawn to the same scale as the Sudan seed.

However, not all hybrid seeds are distinguishable by seed character.

Sorghum (pi. XI, 188-194) : The sorghums are commonly classified

as grain or sweet sorghums (sorgo). There are many horticultural

varieties in each group. The sweet sorghums are represented in the

illustrations by the variety Sumac, which is completely hulled in the

threshing process, and Black Amber, the grain of which remains in the

glumes. The grain sorghums are represented by the varieties Kafir,

Hegari, Feterita, and Milo.

SEED KEY

A. Glumes and pedicels ^^ persisting ; spikelet narrowly to broadly elliptic.

a. Base with smooth callus ; pedicels expanded and cuplike at apex.

Glumes 4% mm. long, ly^ to 2 mm. wide; hulled grain broadest

above the middle, pointed toward the base, flattened dorsoventrally Sorghum halepense, Johnson grass (pi. XI, 185).

Glumes 6 to 7 mm. long, 3 to S^^ mm. wide; hulled grain oval or

broadly elliptic, not markedly flattened dorso-ventrally.

Sorgnum-ßudan hybrids (pi. XI, 187).

&. Base without smooth callus ; pedicels not expanded and cuplike at the

apex.

Glumes 5% to 6 mm. long, 2 to 2i/4 mm. wide ; hulled grain broadest

below the middle with obtusely pointed base; flattened dorsoventrally S. sudanense, Sudan grass (pi. XI, 186).

Glumes 6 to 7 mm. long, 3 to 31/2 mm. wide; huUed grain oval or

broadly elliptic, not markedly flattened dorso-ventrally.

Sorgfium-Sudan hybrids (pi. XI, 187).

B. Glumes, if present, not close fltting on the grain, pedicels usuaUy lacking;

grain broadly elliptic, orbicular, or obovate, not flattened dorso-ventrally,

or only slightly so.

a. Embryo area plane, sUghtly elevated, with margined rim; grain commonly ivory with reddish brown spots ; in edge view, both sides curved,

base short-pointed S. vulgäre var. Kafir (pi. XI, 191).

Ö. Embryo area depressed, margin not rimmed, a very short ridge at the

base.

aa. Grain orbicular, bluish or chalky white, sometimes with reddish

brown spots, subcoat red-brown.

Surface distinctly crackled; length 5 mm., width 5 mm.; in

edge view, one side straight, the other side curved, the

long-pointed base off-center.

8. vulgäre var. Feterita (pi. XI, 193).

Surface smooth or only slightly crackled ; length 4^^ to 5 mm.,

width 4 mm. ; in edge view, both sides curved, the base

scarcely pointed 8. vulgäre var. Hegari (pi. XI, 192).

1)1). Grain obovate, the base long-pointed ; color salmon or brownish ;

glumes, if present, with a transverse wrinkle below the

middle 8. vulgäre var. Milo (pi. XI, 190).

c. Embryo area neither distinctly elevated nor depressed, a coarse ridge

extending to top of embryo area or nearly so ; grain buff or brown.

Grain in edge view top-shaped or elliptic ; glumes shorter, equal to,

or longer than the grain.

8. vulgäre, Sweet sorghum (pi. XI, 188-189).

Grain in edge view thickened below the middle, tapering toward the

top ; glumes about equal to grain, tan, red, or dark brown.

Ä. vulgäre var. technicum, broomcorn (pi, XI, 194).

" The rachis segment and pedicel of sterile spikelet.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 231

SPOROBOLUS—DROPSEED

(PL XII, 196-198)

The spikelets of dropseed are one-flowered, disarticulating above

the glumes. The caryopsis is free from the lemma and palea and

falls readily from the spikelet at maturity.

Two native species are utilized for range reseeding: Sfovoholus

airoides^ alkali sacaton ; and S. cryftandrus, sand dropseed. Seeds of

these two species, as well as S, neglectus^ puff dropseed, and S. damdestinus^ scratch dropseed, may occur incidentally with crop seeds.

SEED KEY

A. Lemma silvery and transparent, or opaque in neglectus; free grains oval,

flattened, semitranslucent.

a. Free grains yellowish brown, smooth or nearly so; embryo area less

than y2 the length of the grain ; length IVé. mm., width % mm.

SporoJjolus cryptandrus, sand dropseed (pi. XII, 197).

Ô. Free grains yellowish brown with dark brown spots ; striate lengthwise

and sometimes pitted; embryo area prominent, about % the length

of the grain ; length 1% mm., width 1 mm.

<Si. neglectus, puff dropseed (pi. XII, 198).

B. Lemma yellowish or grayish, not silvery; free grains oval, flattened, duU

dark brown, strongly striate lengthwise; length 1% mm., width 1 mm.

;Sf. airoides, alkali sacaton (not illus.).

G, Lemma duU grayish brown flecked with purple, sparingly long-pubescent,

length (including awn) 10 to 15 mm.; free grains oblong, flattened, yellowish brown, semitranslucent, minutely striate or nearly smooth ; embryo

area about % the length of the grain ; length 3i^ mm., width 1^/4 mm.

S. clandestinus, scratch dropseed (pi. XII, 196).

ZOYSIA

(PI. XII, 202-203)

Seeds of two species of Zoysia^ie available commercially : Z. japónica, Japanese lawn grass; and Z, matrella, Manila grass. The latter

is reported to be the more widely used of the two species. Another

species, Z. tenuifolia, Mascarene grass, is in experimental plantings.

The plant is a poor seeder under conditions in this country and the

seed is not in the trade at the present time.

The spikelets are 1-flowered, laterally compressed, disarticulating

below the glumes. The first glume is wanting; the second glume is

hard and stiff, smooth, short-awned, and completely enfolding a thin

lemma and palea. The thin palea is sometimes lacking. The usual

commercial seed consists of the caryopsis firmly locked in the hardened

second glume. Hulled grains are usually found only in severely

milled samples.

SEED KEY

A. Seeds broadly ovate, short-pointed or short-awned; length (excl. of awn)

3% to 4 mm., width 1^2 mm. ; color dull brownish, commonly with a purplish tinge Z. japónica, Japanese lawn grass (pi. XII, 202).

B. Seeds narrowly lance-shaped, short-awned; length (excl. of awn) 3 to 3i^

mm., width 1 mm. ; color bright yellowish straw color.

Z. matrella, Manila grass (pi. XII, 203).
232 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

CARYOPHYLLACEAE (PINK FAMILY)

(Pis. XV-XVI, 273-293)

The seed pods of plants in the pink family are usually 1-celled

and many seeded. The seeds, attached to the base or to a central

column in the pod, have a hilum or scar that is characteristic of the

family. The slender embryo is coiled or curved around the outside

of a mealy endosperm, except in Dianthus where it is nearly straight.

The species under consideration are of interest chiefly as field weeds.

They include such well-known weeds as chickweed, spurry, cow cockle,

campion, catchfly, and corncockle.

Z,rCHiV/S—CAMPION; AND S/iiSAÎ^fi—CATCHFLY

(PI. XV, 279-280, 283-291)

Plants of these two genera differ only in minor features, and the

same is true of their seeds. The two groups are included in one seed

The seeds are hemispheric or kidney-shaped, often asymmetrical

and angular, slightly flattened laterally ; color black, reddish brown,

or gray, with black-tipped protuberances or tubercles arising from

minute interlocking grayish plates. The plates may be roughly oblong or circular, with variously indented margins. The color of

these plates gives the seeds a light gray or a darker steel gray aspect.

The shape of the plates may be a useful diagnostic feature in some

cases.

The hilum or scar may be a tranverse slit or an oval cavity. In

certain species the cells around the scar become elongated, forming

a collar wholly or partially surrounding the scar, or they may form

two padlike structures overlapping the ends of the oval scar cavity.

The character and arrangement of the protuberances or tubercles,

and the shape and position of the elongated cells at the scar are important diagnostic features.

With the possible exception of L, dioica^ red cockle, the species

described in the key are found commonly with crop seeds. Silène

crética^ no common name, occurs in imported seed, such as crimson

clover.

SEED KEY

A. Elongated cells at the scar collarlike; scar a circular or oval cavity; 'i^í

to 2 mm. across or larger.

a. Collar high, completely surrounds scar cavity, or nearly so ; tubercles

fine, pointed, so close-spaced the seed may appear minutely spiny,

not arranged in a pattern ; grayish plates very small, roundish.

Lychnis dioica, red campion (pi. XV, 280).

1). Collar shorter, surrounds % to % of scar cavity ; tubercles short, blunt,

not close-spaced like above, not arranged in a pattern ; grayish plates

very small, roundish Lychnis alha, white cockle (pi. XV, 279).

B. Elongated cells at the scar in two padlike structures, one on each side of the

oval scar cavity.

a. Cells of pad long, narrow, so that pads appear finely striate.

Seeds 1% to 2 mm. across, ñattened, angular ; tubercles pointed,

in 4 or 5, often interrupted, concentric rows on the sides of seed ;

rows indefinite in edge view of seed ; grayish plates oblong.

Silène cuaibalus, bladder campion (pi. XV, 289).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 233

&. Cells of pad narrow, uneven in length.

Seeds 11/2 mm. across; thick, with rounded margins; tubercles

short, blunt, crowded, not arranged in a pattern ; in edge view

tubercles usually in rows both above and below the scar ; grayish

plates roundish or linear oblong.

8. noctíflora, night-flowering catchfly (pi. XV, 291).

c. Cells of pad broader, uneven in length.

aa. Seeds ll^ to 2 mm. across ; tend to be asymmetrical and obtusely

angled; tubercles short, blunt, in 3 or 4 concentric rows on

the sides ; in edge view tubercles appear crowded, not in distinct rows above the scar ; grayish plates oblong, prominent.

S. dichotoma, forked catchfly (pi. XV, 290).

hh. Seeds 1% mm. across ; more uniform and symmetrical in shape

than dichotoma; tubercles as in dicJwtoma but in edge view

appear in 3 or 4 distinct rows above the scar ; grayish plates

oblong iSi. cserei, no common name (pi. XV, 288).

cc. Seeds 1/2 to % mm. across; thick, with rounded margins,

scarcely flattened laterally ; tubercles pointed or blunt, large

for the size of the seed, not arranged in a pattern; grayish

plates roundish__ /S. antirrhina, sleepy catchfly (pi. XV, 283).

C, Elongated cells at the scar lacking or much reduced.

a. In side view scar lies within a narrowly or broadly U-shaped cleft or

sinus ; seed flattened laterally, margins angular.

aa. Scar a narrow transverse slit.

aaa. Seeds li/4 mm. across ; tubercles short, flne, inconspicuous, in 2 or 3 concentric rows along the margins,

no pattern above; in edge view tubercles in about

4 poorly defined rows above the scar, the linear grayish

plates lying in a transverse position.

ASf. conoidea, no common name (pi. XV, 286).

bhh. Seeds 1% to 2 mm. across; tubercles linear with sharp

edge at the top or rounded and knoblike, arranged in

somewhat indistinct concentric rows on the sides ; in

edge view, knobs above scar very large, the bases

touching, not in rows, below the scar much smaller.

S. crética, no common name (pi. XV, 287).

dh. Scar an oval cavity : Seeds 1 mm. across ; a depressed, crescentshaped area of elongated cells below the scar; tubercles

short, fine, inconspicuous, not in rows ; grayish plates linearoblong S. gallica, English catchfly (pi. XV, 284).

&. In side view scar lies within a shallow indentation: Seeds 1% mm.

across, thick, with obtusely angled margins; tubercles long, fine,

pointed, in about 3 concentric rows near the margins, no pattern

above ; in edge view, tubercles stand out in 3 or 4 sharp, wide-spaced

rows above the scar, crowded and much smaller below the scar;

grayish plates oblong or diamond-shaped.

S. cónica, conical catchfly (pi. XV, 285).

CRUCIFERAE (MUSTARD FAMILY)

(Pis. XVI-XVIII, 310-344)

The pods of plants in the mustard family are usually two-celled,

the two valves separating at maturity. The pod may be much longer

than broad, or shorter, sometimes indéhiscent and nutlike, or

separating across into one-seeded joints.

The seeds, without endosperm, are filled by the large embryo which

is folded or curved in various ways. As shown in the illustrations,

the position of the cotyledons and radicle as seen in cross-section is
234 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

often helpful in making an identification when considered with

other features of the seeds.

The mustard family includes a great variety of plants. Many of

them are economically important, particularly in the genus Brassica,

Some species are noxious weeds while others are objectionable field

weeds when they occur in quantity.

BRASSICA 13

(Pis. XVI-XVII, 315-319)

As pointed out in the seed key that follows, seeds of Brassica (including rape, cabbage, mustard, and related kinds) are distinguished

chiefly by the configuration of the seed surface. The main distinguishing features include the following: (1) The nature of the

reticulation or network of lines or ridges; (2) the size of the spaces

between the lines of the network; and (3) the size of the microscopic

pits or stipples. The interspaces vary somewhat in size and shape

on different parts of the seed, and the seed key refers to those most

frequently seen along the median part of the seed. The distinguishing features are all microscopic in size and can be recognized only

under a magnification of about 20 to 40 diameters.

Seeds of some of the species are very similar, and individual seeds

cannot be identified with certainty in all cases. Likewise, seeds of

closely related groups, such as certain turnips and turnip-rapes, cannot

always be distinguished.

SEED KEY

A. Seeds pale straw color or yellow.

a. Seeds small (less than 2 mm.) ; stipples distinct.

aa. Reticulations fine distinct lines.

B. júncea, brown or India mustard (not illus.).

ftö. Reticulations lacking or only faint lines.

B, campestris var. sarson, Sarson (not illus.).

b. Seeds large (2 mm. or more) ; stipples not evident; reticulations thick

and indefinite or obscured ; interspaces very small.

B. hirta, white mustard (not illus.).

B, Seeds grayish black, dull brown, or reddish.

a. Seeds large (2 to 3 mm.).

aa. Stipples small, dull or shiny ; interspaces small, shallow, poorly

defined (except in olerácea).

aaa. Reticulations thin, flat.

B. napus var. biennis, winter rape (pi. XVI, 318).

bhi). Reticulations thicker than the var. biennis, not sharply

defined ; stipples on ridges plainly evident.

B. napus var. annua, summer rape (not illus.).

B. napus var. pabularia, Siberian kale (not illus.).

ccG. Reticulations narrow, well-defined lines ; stipples minute.

B. olerácea, cabbage (not illus.).

bb. Stipples large, shiny ; interspaces large, shallow, poorly defined ; reticulations broad and thick.

B. napus var. napobrassica, rutabaga (not illus.).

"For a more complete treatment of the genus Brassica, see Distinguishing

the Species of Brassica by Their Seed. By A. F. Musil, U. S. Department of

Agriculture. Misc. Pub. 643. 1948. pp. 35. iUus.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 235

&. Seeds small (less than 2 mm.). Some exceptions in campestris, júncea,

peMnensis.

aa. Stipples minute, partially obscured.

aaa. Reticulations fine, poorly defined, or obscure; interspaces very small.

B. JcaJ)er, charlock (pi. XVII, 317).

dhb. Reticulations prominent silvery lines ; interspaces small.

B, tournefortii, Mediterranean wild turnip (not illus.).

ccc. Reticulations distinct, thick raised lines; interspaces

large, concave, glossy.

B. nigra, black mustard (pL XVII, 319).

hh. Stipples larger, distinct, dull or shiny.

aaa. Reticulations distinct fine lines devoid of stipples;

interspaces large, shallow, not concave.

B. júncea, brown or India mustard (pi. XVII, 316).

hM. Reticulations fine ridges with stipples evident; interspaces very small but well defined; stipples shiny,

prominent.

B, campestris, turnip-rape and turnip (pi. XVI, 315).

ccc. Reticulations reduced or lacking ; interspaces very small

(larger in pekinensis), poorly defined, in occasional

seeds larger and distinct.

B. perviridis, spinach mustard (not illus.).

B. pekinensis, Pe-tsai (Chinese cabbage) (not illus.).

B. cMnensis, Pakchoi (celery-mustard) (not illus.).

CARDARíA

(PL XVII, 322-323)

Cardaría draha and its var. repens, which were formerly included

with the genera Lepidium and C. pubescens^ are noxious weeds.

Several common names of these plants are in local usage. These

names may be found in the List of Plant Names near the end of this

Manual. i T

Well-developed, mature seeds of the two species appear to be distinguishable. However, because there are intergrading and off-type

forms, individual seeds cannot be identified as to species in all cases.

The more typical seeds are described below.

CardaHa drala, hoary cress (pi. XVII, 322) : The seeds are reddish brown; length 21/2 nim. or more, width about 2 mm.; oval,

slightly flattened laterally and markedly thicker on the cotyledon

edge than on the radicle edge, the surface roughened by minute reticulations ; the tip of the radicle is usually even with the tip of the

cotyledons.

Seeds of Cardaría drdba var. repens^ lens peppercress (not illus.),

are usually not distinguishable from the species. The tip of the

folded cotyledons tends to overtop the tip of the radicle as in C, pubescens, but other features are similar to those of C, draba.

Cardaría pubescens, ballcress (pi. XVII, 323) : The seeds are reddish brown; length 2i^ mm. or more, width about 2% mm.; broadly

oval, slightly flattened laterally, the thickness of the seed about equal

throughout. The surface reticulations are extremely minute and the

seed appears smoother than C, drdba.

957116—52 16
236 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

CHORISPORA

Ghorispora tenella^ no common name (pi. XVII, 324) : The elongated pod breaks up into hard, indéhiscent joints which are commonly considered the seed. They may be found in crops such as

alfalfa from States west of the Mississippi Eiver. The soft and mealy

grain would not be likely to occur in processed seed.

The joints or seeds are brownish and rectangular in shape; length

2 to 23^ mm., width 1% to 2 mm., thickness about li^ mm. ; one side

is straight or convex longitudinally, obscurely veined ; the other side

convex, with a rough, corky tissue between wide smooth margins.

CONRINGIA

Conringia orientdlis^ hares-ear-mustard (pi. XVII, 325) : The seeds

are narrowly oblong, often asymmetrical, length approximately 3

mm., width li^ mm. or more ; color light reddish brown, with a bubblelike surface when viewed under magnification. The folded cotyledons are slightly flattened on the back so that the seed stands on a

plane surface with the radicle side uppermost. The radicle is large

and thick, with a slight groove on either side throughout its entire

length, the tip usually bent to one side. Compare with the smaller

and rougher seed of Lepidiwn campestre. The seed may be found

with such crop seeds as clover and alfalfa, both domestic and imported

seed.

CORONOPUS

Goronopus didym/as^ wart-cress (not illus.) : The pod consists of

two flattened, indéhiscent segments. The segments break apart

readily and they may occur in both domestic and foreign crop seeds.

The free grains are found occasionally in processed seed.

The segments are ivory to brownish in color ; shape roughly hemispheric, about 2 mm. across, strongly reticulate or wrinkled. The

long axis of the seed has an open slit or cavity about 1 mm. long,

surrounded by a wide callus.

The grains are sickle-shaped, flattened, minutely reticulate, the

interspaces shiny ; length about 1% mm. The cotyledons are folded

back, their margins evident as two ridges on the sides of the seeds ;

the tip of the radicle markedly longer than the tip of the cotyledons.

ERUCA

Eruca sativa^ salad-rocket (pi. XVII, 326) : The seeds are oval or

oblong, length approximately 3 mm., width 2^4 nim. or more, slightly

flattened laterally ; color yellowish to light brown or greenish, usually

with two green lines on each side of the radicle, outlining the margins

of the two cotyledons. The position of the radicle and folded cotyledons is plainly evident on the surface of the seed. The seeds may

occur incidentally with such crops as alfalfa and flax, especially in

imported seeds.

LEPIDIUM

Lepidium campestre^ field mustard (pi. XVII, 331) : The seeds

are oval to obovate, length approximately 2 mm., width li^ mm. or

more; color dull, dark brown, the surface roughened by minute

tubercles. (Compare with the smoother surface of Conringia orientalis,) The folded cotyledons are distinctly flattened on the back so

that the seed stands firmly on a plane surface, with the radicle side
TESTING AGRICULTURAL AND VEGETABLE SEEDS 237

uppermost. The radicle flattens out toward the tip and is not bent

to one side as in Gonringia, This seed is a common impurity in various crop seeds.

Lepidium latifolimn^ perennial mustard (pi. XVII, 333) : The

seeds are oval or broadly oblong, flattened laterally, the cotyledon

edge markedly thicker than the opposite or radicle edge; length

approximately 1% mm., width 1 mm. ; color light reddish brown, the

surface very minutely reticulate. The seed is very similar to that

of shepherds-purse {Co.psella hursa-pastoris)^ but the latter is narrowly oblong and the thickness is uniform throughout the length of

the seed. The weed is established locally in the Pacific Northwest.

RORIPPA

Rorippa austríaca, yellow fieldcress (pi. XVII, 339) : The seeds

are broadly oval and variously warped ; length and width about equal,

% to 1 mm.; color light reddish brown; the surface coarsely reticulated, the interspaces shiny.

The weed is established locally on the Pacific coast and in the Northeastern States. Because of its small size, the seeds would be likely to

occur only with the finer grass seeds.

Rorippa sylvestris^cv^^^mgyQllçmcr^^s (pi. XVIII, 340) : The seeds

are broadly oval ; length and width about equal, 1/2 to 3^ mm. ; color

light reddish brown ; the surface very minutely reticulated, the interspaces shiny. The seeds are rarely found in crop seeds.

SISYMBRIUM

ßisymbrium irio, tansy mustard (not illus.). The seeds are narrowly oblong, scarcely flattened, length approximately li/4 ïïip-5

width 1/2 iïii^-5 color yellow to light buff, glossy; the tip of the radicle

exceeds the tip of the folded cotyledons. The weed is locally established in the Southwest.

LEGUMINOSAE (LEGUME OR PEA FAMILY)

(Pis. XVIII-XXIII, 353-468)

Seeds of species in the legume family vary greatly in size, shape,

and surface character but, as shown in the illustrations, all the species

under consideration possess a hilum or scar that may be recognized

as characteristic of the family.

The hilum is usually an oval or oblong area, with a groove or slit

down the middle. The area may be minute, as in some of the clovers,

or it may be large enough to be seen without magnification, as in vetch.

In some species the hilum is obscured by a persisting layer of corky

tissue, as in the cowpea. The size, shape, and position of the hilum are

important diagnostic features.

For convenient reference, the genera of the family are arranged

alphabetically, and seed keys have been prepared for the larger groups.

ADESMIA

Adesmia muricata, no common name (pi. XVIII, 353) : The seeds

are somewhat heart-shaped, flattened, length 2 mm. or more, width

Vy2 to 2^2 mm., gray or brownish and mottled with black, somewhat

glossy ; scar less than i/^ mm. long, usually in a wide shallow notch.
238 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

The pods are several-jointed, flattened, the segments with short

spines and sparingly white-hairy.

The presence of this seed in a sample is indicative of Argentine

origin,

AESCHYNOMENE

Aeschynomene virgrinica, Northern jointvetch (pi. XVIII, 354) :

Seeds are roughly sickle-shaped, length 2i^ mm., width 4 mm., dark

or light reddish brown, smooth and semipolished; scar about 1 mm.

long, concave, below a hooklike projection near one end of the long

axis of the seed, the chalaza a prominent elevation at the other end of

the scar.

The pods consist of 5 to 10 nearly square, flattened joints, the joints

wrinkled or tubercled in the middle portion.

The species occurs along the eastern and southern Coastal Plain

and may be found as an incidental seed in rice.

ALHAGI

Alhagi pseudalhagi^ camelthorn (pi. XVIII, 355) : The seeds are

roughly oblong or oval, length 2 mm. or more, width 3 to 31/2 nim.,

greenish or reddish brown and obscurely streaked or flecked with

black ; scar usually nearer one end on the long axis of the seed, may be

in a shallow indentation or in a distinct notch.

The pods are jointed, light reddish brown in color, length of segment about 4% mm., width 3 mm.

Seeds of camelthorn have been found in imported Turkestan alfalfa.

The plant has become locally established in southern California but,

insofar as known, it has not been found in domestic crop seed.

ALYSICARPUS

Alysioarpits vaginalis^ Alyce clover (pi. XVIII, 356) : The seeds

are approximately 1^4 nim. long, 2 mm. wide ; oblong, flattened, in edge

view seed is broader at the ends than at the middle ; smooth, glossy,

mostly yellowish brown and finely stippled with dark purple; occasional seeds greenish or reddish without stippling; scar in shallow

indentation near the middle on the longer axis of the seed.

The species is adapted to the Southern States and is in limited production in Florida.

ANTHYLLIS

Anthyllis vulneraria^ kidneyvetch (pi. XVIII, 357) : The seed is

oval, length 2% to 3 mm., width li^ mm., semipolished, green below

the scar, yellowish above ; scar in a broad, shallow indentation on the

side, near the middle of the seed ; the chalaza a brownish spot at one

end of the seed.

Kidneyvetch is not cultivated as a crop in this country. The seed

may occur incidentally in such crops as crimson clover or alfalfa.

ASTRAGALUS—LOCO ; MILKVETCH

(PI. XVIII, 358-363)

The genus Astragalus comprises hundreds of species of world-wide

distribution. These include the poisonous locoweeds and some species

which appear to have forage value. At the present time certain

species are in experimental plantings in various parts of the country.

Six species are illustrated and described. The species are readily distinguished by surface character, shape, size, and color.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 239

SEED KEY

Light olive green with black mottling, slightly glossy ; variously shaped,

slightly flattened; scar in a deep notch; length about IV2 nim., width

2 to 2^/^ mm.—Astragalus fleœuosus, flexuous milkvetch (pi. XVIII, 361).

B. Surface mottled.

Dull brownish with minute black mottling ; square or rectangular, flattened, the margins angled ; scar in a deep notch about the middle of one

edge ; length 1% to 2 mm., width 2 to 2% mm.

Astragalus nuttallianus, nuttall milkvetch (pi. XVIII, 362).

C. Surface not pitted or mottled.

a. Length approximately 2 mm., width IV2 nim.

Light greenish brown, rarely with a few purplish flecks; rectangular, flattened, margins often angled; sear off-center on one

edge ; usually a depression below the scar between the radicle

and cotyledons.

Astragalus rudyi, ruby milkvetch (pi. XVIII, 363).

Ô. Length more than 2 mm.

Dull olive green ; roughly oval, slightly flattened ; scar on one side

just above the middle.

Astragalus chinensis, Chinese milkvetch (pi. XVIII, 358).

BufC color to brown ; heart-shaped, flattened, with rounded margins ;

scar between the two lobes near the top.

Astragalus deer, chickpea milkvetch (pi. XVIII, 359).

Rectangular, flattened, margins often angled ; scar near the middle

of one of the longer edges.

Astragalus falcatus, sicklepod milkvetch (pi. XVIII, 360).

CASSIA

Oassia nictitans^ sensitive pea (pi. XIX, 364) : The seeds are rectangular, flat, length 4 to 5 mm., width 31/2 mm., dull black, with TOWS of

minute pits; scar very minute, atthe base of a pointlike projection near

one end of the shorter axis of the seed.

GassiatoTa^ sicklepod (pi. XIX, 365) : The seeds are thick, the long

axes obtusely angled, the sides transversely arched, length 4 to 5 mm.,

width 3 mm.; glossy, light brown, with a light-colored band lying

diagonally across the arched sides; scar minute, at one end of the

long axis of the seed.

The two species are of interest as field weeds.

crcER

Cicer arietinum^ chickpea or garbanzo (pi. XIX, 366) : The seeds

are roughly globular, 8 to 9 mm. in diameter, slightly flattened and

lobed on one side with the scar at the pointed end and the chalaza

about midway, the other side of seed globose ; surface slightly roughened by minute raised lines ; the color is commonly dull creamy white

or brownish, or black in some varieties ; scar is oval, about IV2 nim.

long, depressed.

Chickpeas are in limited cultivation in California.

CORONILLA

Ooronilla varia^ crownvetch (pi. XIX, 368) : The seeds are narrowly oblong, slightly flattened, length 1 to 1% mm., width 4 to 5 mm.,

dull reddish brown ; scar less than one-half mm. long, lies in a broad

indentation about the middle of the long axis of the seed; chalaza

inconspicuous, not adjacent to the scar.
240 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

Creeping crownvetch is in experimental plantings for ground cover

purposes ; the seeds may occur incidentally in imported alfalfa and

clovers.

Goronilla scorpioides, scorpion crownvetch (pi. XIX, 367) : The

seeds are narrowly oblong, slightly flattened and usually curved, often

with a faint longitudinal line on each side ; length 1 to 1% mm., width

4 to 5 mm. ; dull reddish brown ; scar less than one-half mm. long,

lies in a shallow indentation on the convex side ; chalaza inconspicuous, not adjacent to the scar.

The seed occurs incidentally in importations of alfalfa and clover.

CROTALARIA

(PI. XIX, 369-372)

Four species of crotalaria are utilized to some extent for forage and

soil improvement in the Southern States: Orotalaria intermedia^

slenderleaf crotalaria; 0, mucronata {G, striata)^ striate crotalaria;

O. lanceolata^ lance crotalaria ; and G, spectatilis^ showy crotalaria.

Another species, G, júncea^ sunn crotalaria, does not seed well under

most conditions in the South and is not in general use because of

insufficient seed. The species are readily distinguished by color, size,

and shape.

SEED KEY

A. Seeds salmon-colored, glossy.

a. Length approximately 3 mm., width 2% to 2% mm. ; oval ; scar within

a deep notch on one side just above the middle.

Crotalaria intermedia, slenderleaf crotalaria (pi. XIX, 369).

Ô. Length 2 to 21/^ mm., width 2 mm. or less ; oval ; scar within a shallow

notch on one side just above the middle.

(7. lanceolata, lance crotalaria (pi. XIX, 370).

B. Seeds dark olive green, oval; scar below a hooklike projection near the

middle of one side.

a. Length 4 to 4% mm., width 3 to 3% mm. ; a whitish waxy area around

the scar G. spectaMUs, showy crotalaria (pi. XIX, 372).

&. Length 6 to 7 mm., width 4^/^ to 5 mm. ; whitish area around scar

lacking 0. júncea, sunn crotalaria (not illus.).

C. Seeds greenish or brownish, variously streaked and spotted with dark olive

green, occasional seed not spotted or streaked. Length 3 mm., width 3

mm. ; broadly heart-shaped, scar between the two lobes at the top.

C. mucronata (C. striata), striate crotalaria (pi. XIX, 371).

CYAMOPSIS

Gyamopsis tetragonolohus^ guar (pi. XIX, 373) : The seed of guar

is obtusely angled or almost circular, flattened, the surface roughened

by minute tubercles ; length and width about equal, 4 to 5 mm. ; color

mostly pearl gray or yellowish, with a few seeds purplish or brown ;

the scar is in a shallow indentation, usually off-center.

The crop is in limited production in the Southwest.

DAUBENTONIA

Daubentonia texana^ rattlebox (pi. XIX, 374) : The seeds are

broadly oval to semicircular, scarcely flattened, length 5 mm. or more,

width 6 to 7 mm., light to reddish brown or yellowish ; scar oval, 1%

mm. long, near the middle of the long axis of the seed, the chalaza at

the end of the axis.

Seeds of this species may occur incidentally with rice.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 241

DESMODIUM

Desmodium tortuosum^ Florida beggarweed or tall tickclover (pi.

XIX, 375) : Seeds are oval or ovate, flattened and usually slightly

warped, length 1% to 2 mm., width 3 mm., glossy, reddish brown;

scar less than i/^ mm. long, depressed, with a fine lighter colored collar

around the margin ; the chalaza is distinct at one end of the scar.

The pods are flat, several-jointed, the segments oval or ovate and

more or less warped when dry, brown, short pubescent, and with a

distinct network of fine nerves on the sides.

The species is in limited cultivation as a hay and green manure

crop in the Southeastern States.

GALEGA

Galega oßcinalis^ galega (pi. XIX, 376) : Seeds of galega are oblong, somewhat flattened, length 1% to 2 mm., width 4 mm., dull olive

green or brownish; scar, less than ^ mm. long, in a broad notch about

the middle of one of the longer sides of the seed; usually a wide

depression below the scar between the radicle and cotyledon; the

chalaza not adjacent to the scar.

Seeds of galega may occur incidentally in Italian red clover and

alfalfa.

GLYCINE

Glycine maœ^ soybean (pi. XIX, 377) : There are morp than 100

named varieties of soybeans handled by domestic growers according

to Morse {88), These are grouped according to utilization into industrial, forage, and vegetable classes.

Seeds of the varieties vary considerably in size, shape, and color.

The shape may be oval to almost spherical, or distinctly flattened.

The scar is flush with the surface of the seed, narrowly oblong, the

slit down the center usually curved in the lower half of its length.

The surface is smooth, the color varying with the variety from yellowish to greenish yellow, bright green, reddish brown, or black. The

species is represented in the illustrations by the variety Hawkeye.

HEDYSARUM

Hedysarum coronariuon^ sulla (pi. XIX, 378) : The seeds are

broadly ovate to orbicular, becoming narrower above the scar, in edge

view lens-shaped, length 2 to 3 mm., width 2^/^ to 3 mm. at widest

point; glossy, reddish brown with a variable proportion of yellowish

seeds; scar about % mm. long, in a deep V-notch near the narrower

end of the seed.

The pod consists of several flat, light brown, spiny segments, length

of segment about 5 to 6 mm., width 4% mm., the smooth callus at

each end about 1% mm. long.

Sulla has been grown experimentally in the United States but is

not in cultivation at the present time. The seed may occur incidentally with imported crop seeds from southern Europe.

HOFFMANNSEGGIA

Hoffmannseggia sp., rushpea (pi. XIX, 379) : Seeds are obovate,

flat, length 3 mm., width 2 mm., color light to dark olive green, semiglossy ; scar minute, in an indentation at the pointed end of the seed.

The seed may occur incidentally in alfalfa and is indicative of

Argentine origin.
242 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDIGOFERA

Indigofera hirsuta^ hairy indigo (pi. XIX, 380) : The seeds are

4-sided, somewhat rhomboidal in shape, length and width about

equal, 1% to 2 mm.; surface pitted, yellowish to reddish brown in

color; scar less than ^^ mm. in length, depressed, lies in about the

middle of one of the angles.

Hairy indigo is in limited use as a pasture plant in the Coastal

Plain area from Florida to Texas.

LATHYRUS—VETCHLING

(PI. XIX, 381-385)

Ten species of Lathyrus are described which are of interest as crop

plants or as contaminants of crop seeds.

GENERAL DISTINGUISHING FEATURES

Three species are in limited cultivation : Lathyrus hirsutiùs^ rough

pea,^ also known as Caley pea, Singletary pea, and wild winter pea ;

i. tingitanus^ Tangier pea; and L. sylvestris^ flat pea. As described

in the seed key and shown in the illustrations, seeds of these three

species are readily distinguished. Z. hirsutus also occurs as a contaminant in vetch and grain seed. Seeds of this species from Southern

sources usually have somewhat coarser and more prominent tubercles

than those from the Pacific Northwest.

Seeds of i. anmms (not illustrated) are very similar to L. hirsutus.

This species may occur in imported vetches. It differs from L, hirsutus

chiefly in being more spherical in shape, larger and rougher; the

protuberances are clear-cut, mostly cone-shaped, their bases touching;

the scar is depressed, with a distinct rim around the edge.

Seeds of six species may occur as weeds in vetch and similar crops :

Z. aphaca^ yellow vetchling; Z. stipularis^ slender vetchling; Z. tuherosus^ groundnut pea ; Z. pusillus^ low vetchling ; Z. angulatus^ no common name ; and Z. sphaeHcus,^ no common name. Insofar as known,

Z. stipularis^ (not illustrated) occurs only in importations of oats

from Argentina. As pointed out in the seed key, the seeds are easily

recognized by their small size, shape, and color.

Seeds of Z. tuberosus and Z. hirsutus are very similar. Welldeveloped seeds, as described in the key and shown in the illustrations,

are identified chiefly by shape and surface configuration, but some

individual seeds may be difficult to distinguish with certainty.

Plants of Z. pusillus and Z. angulatus are sometimes confused, but

the seeds (not illus.) are readily recognized by shape and surface

character, as described in the seed key. Z. pusillus occurs chiefly in

eastern and southern United States; and Z. angulatus^ a European

species, is established locally in the Pacific Northwest where it may

occur with vetch or similar crops.

SEED KEY

A. Seed surface smooth.

a. Seed glossy.

Length 4 mm. or more, width 3 mm., broadly oblong or narrower

at scar end, flattened; commonly reddish brown flecked with

black, sometimes pale greenish brown or almost black; scar

elliptic, length % mm., or less, width % mm.

Lathyrus aphaca, yellow vetching (pi. XIX, 381).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 243

Ö. Seeds duU.

aa. Length 2^/2 mm., width 2 mm., narrower at scar end and

variously compressed so that seed appears somewhat angular;

dull buff color flecked with black, occasional seed almost entirely

black ; scar elliptic, length 1 mm., width % mm.

L. stipularis, slender vetchling (not illus.).

&?h Diameter about 4 mm., spherical to broadly oblong; reddish

brown, occasional seeds greenish and minutely spotted with

black, the black spots so obscure on the brown seeds they appear

to be lacking ; scar oval, length 1 mm. or more, width l^ mm. or

more ; chalaza a large dark spot near the scar.

L. sphaericus, no common name (not illus.).

CO. Length 6% to 6 mm., width 7 to 8 mm. ; broadly oblong, flattened ;

dark brown, obscurely streaked or flecked with black ; scar near

one end of the longer axis of the seed, narrowly oblong, length

Sy2 to 4 mm., width 1 mm. or less, with a roll or ridge around

the margin; chalaza a large dark spot near the scar.

L. tingitanus, Tangier pea (pi. XIX, 384).

B. Seed surface not smooth.

a. Scar about % the length of the circumference of seed, linear, width

1/2 to % mm., slightly depressed at edges. Seed spherical or slightly

flattened, 4% to 5 mm. long ; dull reddish brown ; faintly roughened by

flattened wavy ridges L. sylvestris, flat pea (pi. XIX, 383).

Ö. Scar length 2 mm. or less, broadly elliptic or ovate, 1 to 1% mm. wide.

aa. Seeds oval or oblong, length 3 mm., width 41/2 to 5 mm. ; scar

near one end of the longer axis ; surface very minutely stippled

and roughened by rather wide-spaced, flattened ridges or tuberclelike protuberances ; chalaza near one end of scar, not prominent.

L. tuderosus, groundnut pea (pi. XIX, 385).

ÖÖ. Seeds spherical or compressed at the ends, length 3 to 3i^ mm. ;

surface roughened by close-spaced, knoblike tubercles or ridges ;

chalaza a large smooth spot near one end of scar, prominent.

L. hirsutus, rough pea (pi. XIX, 382).

cc. Seeds spherical, l^/^ to 2 mm. long; light reddish brown with

numerous small black flecks; surface minutely stippled, with

an irregular network of high thin elevations ; scar wedge-shaped,

with a high thin rim around the margin.

L. pusillus, low vetchling (not illus.).

dd. Seeds 4-sided, the end plane somewhat triangular with a small

oval scar in the wider angle; reddish or grayish brown, finely

tubercled ; length 2 to 2^/^ mm., width 2 mm.

L. angulatus, no common name (not illus.).

LESPEDEZA—LESPEDEZA

<P1. XIX, 386-387; pi. XX, 388-389)

Three species of lespedeza are commercially important in the United

States. Two of the species are annual plants: Striate lespedeza

(Lespedeza striata) and its varieties Common, Kobe, and Tennessee

76; and Korean lespedeza (Z. stipulacea) with its varieties early

Korean and Climax. Sericea lespedeza, also known as Chinese lespedeza (Z. cuneata^ formerly Z. sericea)^ is perennial. Two other

perennial species, Siberian or rush lespedeza (Z. hedysaroides) and

bicolor lespedeza (Z. hicolor), are of experimental interest but are not

in production at present. Commercial seed of lespedeza may consist

chiefly of seed in the pods, with a variable proportion of free seeds

which have become hulled in the threshing process, or the seed may be

completely hulled by processing.
244 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

GENERAL DISTINGUISHING FEATURES

The single-seeded pods are oval in shape, somewhat flattened, more

or less pubescent, with a network of slender lines or nerves. When

intact, the pod is surrounded by a persistent outer circle of floral

leaves (the calyx) at the base of which are attached three scalelike

bracts.

The chief distinguishing features of seeds of lespedeza are the

length and pubescence of the calyx and shape of the five calyx lobes,

and the shape, color, and position of scar of the hulled seeds. The

hulled seeds are smooth and lustrous, narrowly oval or ovate in outline, with the scar near the narrower end, usually with a distinct

collarlike tissue around it. A plant usually produces two types of

pods, one pointed, the other obtuse. Space does not permit showing

all types in the illustrations.

The identification of seeds of closely related horticultural varieties

is always difficult. When small bulk portions of seed are viewed,

common lespedeza and its variety Kobe may be distinguished by the

larger size of the latter, but because of natural variation individual

seeds of the two kinds cannot be distinguished with certainty. Likewise, the varieties of Korean lespedeza. Climax and Early Korean,

appear to be indistinguishable. In the perennial group, the pods

of sericea lespedeza (Z. cuneata) and Siberian lespedeza (Z. hedysaroides) are readily recognized, but the hulled seeds of the two

species appear to be indistinguishable.

SEED KEY

A. Calyx approximately % the length of pod.

a. Calyx slit nearly to base, lobes linear-lanceolate, appressed-piibescent,

midrib distinct; hulled seeds greenish or light greenish brown, occasionally flecked with purple.

Hulled seeds 2 to 2% mm. long, 1% mm. wide ; pods S^^ to 4 mm.

long, 2 to 21/^ mm. wide, reddish iDrown.

Lespedeza cuneata, sericea lespedeza (pi. XX, 389).

h. Calyx not slit to near the base, lobes broad, obtusely pointed, 3-

nerved, with anastomosing lateral nerves, sparingly pubescent, especially along margins of lobes ; hulled seeds purple with light-colored

flecks or occasionally purplish brown.

Hulled seeds 2 mm. long, ly^ mm. wide; pods 3 mm. long, 2 mm.

wide, reddish L. striata, striate lespedeza (pi. XIX, 386).

Hulled seeds 2^/^ mm. long, 2 mm. wide ; pods 4 to 5 mm. long, 2V2

mm. wide, grayish L. striata var. Kobe (pi. XIX, 387).

B. Calyx approximately % the length of pod.

a. Calyx lobes broad, obtusely pointed, distinctly 3-nerved, not pubescent ;

hulled seed dark purple, not flecked or mottled, scar within a lightcolored area.

Hulled seeds 2^^ mm. long, 2 mm. wide, uniformly oval in outline ;

pods 3 to 3^/^ mm. long, 2^^ mm. wide.

L. stipulaoea, Korean lespedeza (pi. XX, 388).

Z>. Calyx lobes acuminate, sparingly pubescent, midrib distinct; hulled

seed dark purple ; collar around scar prominent.

Hulled seeds 2% to 3 mm. long, 2 to 2% mm. wide ; pods 6 to 7 mm.

long, 4 to 5 mm. wide L. bicolor, bicolor lespedeza (not iílus.).

G. Calyx equal to pod or nearly so, slit nearly to base, lobes acuminate, appressed-pubescent, distinctly 3-nerved ; hulled seeds greenish or light

greenish brown, occasionally flecked with purple.

Hulled seeds 2 to 2^/^ mm. long, 1% mm. wide; pods 3^ to 4 mm. long,

2% mm. wide, grayish brown.

L. hedysaroides, Siberian lespedeza (not illus.).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 245

LOTUS—TREFOIL

(PI. XX, 390-395)

Two species of trefoil are in limited cultivation for forage in the

United States : Birdsfoot trefoil {L.corniculatus) and big trefoil (i.

uliginosus),

There are two botanical varieties of birdsfoot trefoil. One variety,

Z. corniculatus var. arvensis, has broad leaflets; the other variety, Z.

cornieulatus var. tenuifolius has narrow leaflets. The two varieties

are considered by some authors as distinct species: L. corniculatus^

the broadleaf form ; and Z. tentcis, the narrow-leaved form. Seeds of

the two varieties appear to be indistinguishable.

Big trefoil also has two botanical varieties. The more widely used,

Z. uliginosus var. mllosus^ is a pubescent form.^ Z. uliginosus var.

glahriusculus is glabrous or nearly so. Importations of Z. uliginosus

are sometimes a mixture of the two varieties. As pointed out in the

seed key, seeds of the two varieties are distinguished by the presence

or absence of mottling, which appears to be a fairly reliable distinguishing feature.

Three species are of experimental interest and may occur as incidental seeds in crop seeds : Z. purshianus (Z. americanus), prairie-trefoil;

Z. angustissimus^ slenderpod deervetch; and Z. hispidus^ hispid deervetch.

SEED KEY

A. Scar with a distinct coUar, usuaUy of whitish tissue ; seeds broadly oval, or

occasionally oblong in corniculatus.

a. Dull brown, often obscurely flecked with purple ; length about 1% mm.,

width 11/4 to 1% mm Lotus corniculatus (pi. XX, 391).

h. Light olive green, brownish or reddish brown, not flecked or mottled ;

length about IM mm., width 1 mm L. angustissimus (pi. XX, 390).

B. Scar without distinct collar.

a. Seeds broadly oval.

Bright yellow-green or brownish, not mottled, semipolished ; length

about 1 mm., width 1 mm.

L. uliginosus var. gla'briusculus (pi. XX, 395).

Dull greenish or brownish, copiously mottled with purple; length

about 1 mm., width 1 mm.

L. uliginosus var. villosus (pi. XX, 394).

Dull brown or purplish, flecked with dark purple; length about

114 mm., width 1 mm L. hispidus (pi. XX, 392).

h. Seeds oblong, greenish to reddish brown, mottled with darker green

and flecked with black ; semipolished or dull ; length 2 mm., width 3

mm. or more; scar in shallow indentation on the longer axis of the

seed L. purshianus (pi. XX, 393).

LUPINUS—LUPINE

(PI. XX, 396-397)

Three species of lupine are of commercial importance in the United

States: Blue lupine (Lupinus angustifolius) \ yellow lupine (Z.

luteus) ; and white lupine (Z. albus). In recent years nonalkaloid

strains have been developed in all three species.

GENERAL DISTINGUISHING FEATURES

There are several selected strains of Lupinus angustifolius^ three

of which are in use at the present time : Bitter blue, which is the common commercial form (pi. XX, 396) ; alta blue, an alkaloid form; and
246 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

common sweet blue. When viewed in bulk, seeds of the alkaloid strains

appear pale gray, those of the nonalkaloid strains grayish brown. The

darker, brownish color of the latter distinguishes it from the alkaloid

forms but individual seeds in a mixture would be difficult to identify

with certainty.

Two nonalkaloid strains of Z. luteus are in production: Florida

speckled (pi. XX, 397) and white-seeded yellow (not illus.). The

Crescent strain (not illus.), originally selected as a sweet strain, is

mixed sweet and bitter and is not in production. Its seeds differ from

the Florida speckled in having a prominent white crescent-shaped

stripe on each side below the scar. There are also black-seeded strains

in this species.

Two strains of Z. albus^ Alabama White and Hastings, have been in

experimental plantings. The Hastings strain is now in commercial

production. Seeds of these two strains appear to be indistinguishable.

SEED KEY

A, Broadly oval ; scar about 1 mm. long, at one end of the shorter axis.

Seed flattened, dull, creamy white streaked and flecked with black,, or entirely creamy white in some varieties, length 9 mm., width 7 mm., scar not

within a distinct notch Lupinus luteus, yellow lupine (pi. XX, 397).

Seed only slightly flattened, dull, gray or brownish with tiny white spots

and obscure brown flecks, length 8 to 9 mm., width 6 mm. ; scar with a

short black line above it and a triangular black area below it.

L. anffustifoUus, blue lupine (pi. XX, 396).

B. Obtusely 4-angled or semiorbicular, flattened, creamy white with pinkish cast,

semipolished ; size variable, length approximately 10 to 15 mm., width 10

to 12 mm. ; scar 2 mm. long, lies across one of the angles.

L. alhus, white lupine (not illus.).

MEDICAGO—BLACK MEDIC; BUR-CLOVER; ALFALFA OR LUCERNE

(PL XX, 398-403)

Six species in the genus Medicago are of economic interest. Alfalfa

{Medieago sativa)^ with several horticultural varieties, is the most

widely grown. California or toothed bur-clover {M. hispida) and

spotted or southern bur-clover {M. arabica) are in cultivation chiefly

in the West and Southeast, respectively. Black medic or yellow trefoil

{M, Iwpulina) is not an important crop in the United States, although

the seed is available commercially. The seed occurs commonly with

other crop seeds. Buttonclover {M, orbicularis) and cogwheel-clover

{M, tuherculata) represent the group having spineless burs and are

only of experimental interest at the present time. Buttonclover, as

well as the bur-clovers, may occur incidentally with red clover and

alfalfa, chiefly from such sources as Italy and France.

SEED KEY

A. Symmetrically kidney-shaped, flattened, not warped or only slightly so ; scar

less than % mm. long.

a. Scar at base of prominent projection near one end of the long axis of

seed ; seed relatively thin, color light yellow or occasionally brownish,

length 1^/2 mm. or more, width 3 mm.

Medicago araUca, spotted bur-clover (pi. XX, 398).

h. Scar in shallow indentation near the middle of the seed, chalaza a

prominent brown spot near the scar; seed thicker than araMca,

yellowish or light brown, length 1% mm. or more, width 3 mm.

M. híspida, California bur-clover (pi. XX, 399).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 247

c. Scar in deep indentation about the middle of the long axis of seed;

the rounded margin of the seed usually scalloped ; seed yellowish or

light brown, length 2 mm., width 4^^ to 5 mm.

M. tuherculata, cogwheel-clover (pi. XX, 403).

B. Roughly oval to kidney-shaped and variously warped ; scar in a broad indentation near one end in the more oval seeds or in a distinct notch near the

middle in the kidney-shaped seeds ; color greenish yellow or light brown,

length 1% mm. or more, width 2i/^ to 3 mm.

M. sativa, alfalfa (pi. XX, 402).

C. Neither kidney-shaped nor warped.

a. Uniformly ovate, slightly flattened ; scar at base of a projection near

the narrow'er end ; color yellowish to light brown ; length 1 to 1% mm.,

width 2 mm. or more M. lupuUna, black medic (pi. XX, 400).

Ö. Roughly hemispheric, surface roughened by blisterlike protuberances;

scar in deep notch at one end, near the straight edge; color tawny

to reddish brown : length 2^^ to 3 mm., width 3 mm.

M. orUcularis, button-clover (pi. XX, 401).

MELILOTUS—SWEETCLOVER ; SOURCLOVER

(PI. XX, 404-406)

Three species of Melilotus are in cultivation in the United States.

White sweetclover {M, alba) and yellow sweetclover (il/, oßcinalis)

are crops of major importance throughout the Corn Belt and northward into Canada. Sourclover or yellow melilot {M. indica) is grown

chiefly in the South and Southwest. Seeds of any of the three species

may occur incidentally with other crop seeds from these general areas.

GENERAL DISTINGUISHING FEATURES

Melilotus alba^ white sweetclover (pi. XX, 404) : The seeds are

yellow, with a semitranslucent appearance, uniformly oval in shape

and slightly flattened, permitting the seeds to lie flat on a plane surface. In most seeds the hypocotyl forms a distinct angle so that the

base of the seed appears squared off or somewhat pointed, whereas

some seeds are rounded at the base as shown in the illustration. The

scar lies in a broad, shallow indentation near the top, with a wide

white line below it between the radicle and cotyledons. The length

is usually about 2i/^ mm., width li/^ mm., or more, but the size may

vary somewhat with the variety. The pods have a prominent network of coarse nerves, and the papery, five-toothed calyx and curved

stem often persist.

Melilotus o-fficinalis^ yellow sweetclover (pi. XX, 405) : The color

is commonly dull greenish, with a variable proportion of purple mottled seeds, the seeds lacking the semitranslucent appearance common

in white sweetclover. The shape is similar to white sweetclover, but

the hypocotyl does not form a distinct angle so that the base of seed

is quite uniformly rounded. The size tends to average somewhat

smaller than white sweetclover. The pods have a network of coarse

nerves, the elongated reticulations lying crosswise of the pod; the

five-tooth calyx inflated below.

When in the pods, seeds of white sweetclover and yellow sweetclover are usually distinguishable; but, with the exception of the

purple-mottled seeds, individual hulled seeds of the two species usually

cannot be distinguished with any degree of accuracy. There are

several horticultural varieties of both white and yellow sweetclover

in use. Madrid, a variety of biennial yellow, and Willamette and
248 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Evergreen, varieties of biennial white, are some of the well-known

varieties. No attempt has been made to distinguish the seeds of the

various horticultural varieties.

Melilotus indica^ sourclover or yellow melilot (pi. XX, 406) : Seeds

oval, dull olive green, the surface roughened by^ minute tubercles so

that seeds grate when rubbed together. The size averages smaller

than white and yellow sweetclover, usually about 2 mm. long and

1^2 null- wide, often smaller.

ONOBRYCHIS

Onotrychis viciaefolia^ sainfoin (pi. XX, 407) : Seed of sainfoin

is usually in the pod or hull. The pods are almost semicircular, light

straw color, 6 to 7 mm. long ; the sides of pod strongly reticulate and

often toothed, the back edge margined and toothed.

The hulled seeds are about 3 mm., long, 4% to 5 mm. wide, dark

reddish brown, smooth, semicircular, with the scar in a broad shallow

notch slightly off-center on the straight edge of the seed.

Although adaptable throughout the alfalfa regions of the united

States, it is only in very limited production. The seeds may occur

incidentally in imported crop seeds.

ONONIS

Ononis repens^ ononis (pi. XX, 408) : The seeds are roughly orbicular, flattened, length 2% mm., width 2i/^ mm., dull greenish or reddish

brown ; the scar less than l^ mm. long, concave, depressed below the

seed surface, usually lies in a broad, shallow notch. Compare with

the somewhat similar seeds of Medicago orhicularis (pi. XX, 401).

The seed may occur in imported clover and alfalfa.

ORNITHOPUS

Ornithopus sativus^ serradella (pi. XX, 409) : The pods consist of

several indéhiscent, jointed segments, the segments 3 to 4 mm. long, 2

to 3 mm. wide, a smooth callus across each end; color light grayish

brown ; prominently nerved.

Hulled seeds are oval in shape, reddish brown, flattened, the scar in

a slight indentation on one side.

The species is not a cultivated crop in the United States. The indehiscent segments of the pod may occur incidentally in imported

crop seeds. Hulled seeds are not likely to be found in seed samples,

PHASEOLUS—BEAN

Phaseolus aureus^ mung bean, also known as green or golden gram

(pi. XX, 411) : The seeds are oblong and slightly flattened or almost

spherical, length 3^/^ mm., width 4 to 4^^ mm., color light olive green

with usually a darker band around the scar, occasional seed brownish,

semipolished ; scar 1% mm. long, about i^ mm. wide, ovate or oblong,

obscured by a layer of white corky tissue, the layer slightly elevated

above the surface of the seed.

Mung beans are grown in the Southwest for human food and as

a soil-improvement crop.

Phaseolus angulmis^ adzuki bean (pi. XX, 410) : The seeds are

oblong, slightly flattened, length 5 mm., width 7 to 8 mm., glossy,

maroon-colored ; scar 3i/¿ to 4 mm. long, % to % mm. wide, lies near
TESTING AGRICULTURAL AND VEGETABLE SEEDS 249

one end of the longer axis of the seed, obscured by a layer of white

corky tissue flush with the surface of the seed or nearly so.

Adzuki beans are grown to some extent for home use.

PISUM

Pisum sativum var. arvense^ Austrian winter pea (pi. XXI, 412) :

Seeds of Austrian winter pea are spherical, about 6 mm. in diameter,

grayish to reddish brown and minutely spotted with black, frequently

mottled with darker brown; scar ovate, 1^2 to 2 mm. long, usually

scurfy, flush with the surface of the seed ; chalaza about 21/2 mm. from

the scar.

There are many horticultural varieties of field peas, but the variety

Austrian winter is planted most extensively in the United States.

PUERARIA

Pueraria thunbergiana^ kudzu (pi. XXI, 413) : The seed of kudzu

is almost semicircular, the scar in a slight depression about midway

on the long edge and surrounded by an upstanding collar of white

corky tissue, the scar often obscured by a thin layer of white tissue ;

length 3 mm. or less, width 4 to 5 mm. ; color creamy white to light

reddish brown variously streaked and mottled with black, occasional

seeds light reddish brown without mottling.

Adapted to the Southeastern States where it is useful for hay,

soil improvement, and erosion control; it is a poor seeder and the

seed is not in commercial production in this country.

SESBANIA

Seshania exáltala^ sesbania (pi. XXI, 414) : Seed of sesbania is

about 2 to 21/^ mm. long, 4 mm. wide ; oblong, slightly flattened, the

thickness uniform throughout its entire length; scar about % mm.

long, concave, with a narrow^ white rim around the margin; color

greenish to light brown, variously streaked and mottled with black.

Sesbania is planted as a soil-improvement crop in irrigated sections

of the Southwest, and may occur as an impurity in rice in Louisiana.

STIZOLOBIUM

Stizolohium deeringianum^ velvetbean (pi. XXI, 415) : There are

several varieties of velvetbean in cultivation, but only one variety,

the Deering velvetbean, is in production in this country. The plant

is semitropical and adapted to the southern part of the United States.

Seeds of velvetbean are oval, creamy white or gray copiously mottled

with black; length 10 mm., width 14 to 15 mm. The scar is slightly

off-center on the longer axis of the seed, about 5 mm. in length, width

1 mm. or more, surrounded by a thick collar of white corky tissue with

minute folds at the outer margins. The seeds are readily recognized

by the large size and characteristic collar around the scar. The species

is also known as Deering or Florida velvetbean.

STROPHOSTYLES

Strophostyles leiosperma {S, pauciflora), smooth-seeded wild bean

(pi. XXI, 416) : The seeds are oblong and slightly flattened, length

214 mm., width 3 mm. ; glossy, gray, densely spotted with black so

that seed appears almost black ; the scar, about 2 mm. long, is obscured
250 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

by a thick layer of white corky tissue, the seed coat forming a prominent ridge around the margins; the chalaza is prominent, knoblike,

at one end of the scar, as shown in the side view of seed in the

illustration.

The seed may occur incidentally with lespedeza or similar crops.

SWAINSONA

Swainsona salsula^ Austrian peaweed (pi. XXI, 417) : Seeds of

peaweed are circular or broadly oval, slightly flattened, length 2 to

2% mm. in diameter, dull olive green; scar less than % mm. long,

usually with a collar of whitish tissue, lies in a broad shallow

indentation.

The seed may occur as an impurity in Turkestan alfalfa.

TRIFOLIUM—CLOVER

(PL XXI, 418-435; pL XXII, 436-450)

Thirty-four species of the genus THfoliurïi are described. The

species may be grouped on the basis of their current place in agriculture in the United States, as follows :

Species of major agricultural importance are :

T. proGumbens^ large hop clover.

1\ repenSj white clover (including

the variety Ladino).

T, dubium^ suckling or small hop

clover.

T, fragiferum^ strawberry clover.

T, hyhridum^ alsike clover.

T. incarnatum^ crimson clover.

T, pratense^ red clover.

T, resupinatum^ Persian or shaftal

clover {T. suaveolens Willd.).

T, subterraneum^ sub clover.

Species that form productive stands under more restricted local

conditions; some of them not yet in commerce or just coming into

use are :

7\ amMguum, kura or Pellett

clover.

T. caroliniamini. Carolina clover.

T, mediumi^ zigzag clover,

T, michelianum^ big - flowered

clover.

T, nigrescens^ ball clover.

T, striatum^ striate or knotted

clover.

7\ glo'meratum^ cluster clover.

7\ hirtum^ rose clover.

T. lappacemn^ lappa clover.

Crimson clover may contain incidental seeds of T, striatmrh. Seeds

of the latter average smaller and rounder than crimson clover, and

they may be distinguished chiefly by the minute whitish stipples

evident beneath the semitranslucent seed surface. There is a whiteseeded strain of crimson clover, but this is not in production in this

country.

Seeds of T, resupinatum and T, michelianu^i are somewhat similar,

and seed lots of the latter which have come to the writer's attention

have carried an admixture of T, resupinatum. Seeds of T, resupinaturn are glossy, usually pointed at one end, with the scar at about the

middle of the broader end, at the base of a small projection. Seeds

of T. michelianum are dull, with the scar in an indentation at one end,

the distinct projection at one end of the scar lacking ; the base of seed

not pointed.

Zigzag clover (T, medium) resembles red clover somewhat, but

the seeds are thicker and broader at the point of the scar, with a
TESTING AGRICULTURAL AND VEGETABLE SEEDS 251

short curved white line below the scar between the radicle and cotyledons. The purple color common to red clover has not been observed

in this species.

Seeds of T, amhiguvmi^ kura or Pellett clover, are large and flat

and resemble sweetclover in some respects. Compared with sweetclover, seeds of 1\ ambiguum are longer and broader, and the portion

toward the tip of the cotyledons is markedly thicker.

Productive native species in experimental plantings are:

T, vaHegatmn^ whitetip clover. T, toildenovii or T. wormsholdii^

seaside clover (including T, fumhriatmn and T, invoVucratum in

part).

Species of experimental interest or which may occur incidentally

with crop seeds are :

T. agrarium^ hop clover.

T, alexandrinimb^ berseem or

Egyptian clover.

T, angulatum^ crooked clover.

T, arvense^ rabbit-foot clover.

T, hifidum^ pinole clover.

T, Gernuvmi^ drooping-flowered

clover.

T. depauperatuTYi^ poverty clover.

T, graoïlentum^ pin-point clover.

T, micTOcephalwm^ small-headed

clover.

T. microdon^ thimble clover.

T. ornithopodioides^ no common

name.

T, parvißorurrh^ teasel clover.

T, reßexum^ buffalo clover.

T, tridentatwm. tomcat clover.

GENERAL DISTINGUISHING FEATURES

There are many horticultural varieties among the nine major agricultural species, particularly in the red, crimson, sub, and white clovers. Usually itis not possible to distinguish the horticultural variety

of a species by seed character alone.

Seeds of T, dubium and T, procvmibens are very similar. Typical

seeds, as described in the seed key, are readily recognized ; but some

intergrading forms may be encountered that are difficult to identify

accurately.

Cluster clover {1\ glomeratum) may be confused with droopingflowered clover (T. cernuum)^ which is not in cultivation in this

country. As pointed out in the seed key, seeds of T, cernuwm are

more pointed at one end and the surface is a little rougher than that

of T, glomeratum. This difference in surface becomes evident when

the periphery of the seeds is viewed under a magnification of about 20.

However, individual seeds may be indistinguishable.

Seeds of T, omithopodioides may occur in importations of white

clover from New Zealand. Some authors refer this species to the

genus TrigoneUa or to Falcatula, The seeds may be recognized by

the warped heart-shape, small size, and glossy, green-mottled surJEace.

Seeds of the species under consideration may be grouped on the

basis of seed coat into two major divisions: (A) Seed surface

roughened ;^ and (B) seed surface smooth. Seven species are described which have a more or less roughened surface. The protuberances are microscopic and vary in character with the species

from very minute points to wartlike elevations. In general, the degree

of roughness, from minute to coarse, progresses in about the following

957116—52 17
252 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

order : T. angulatum; T. glomeratum; T. cernuum; T, carolinianum;

T. refiexum; T, parviflormn; T, depauperatum, ^

Within group (B) (seed surface smooth), the seeds may be further

divided according to size as small, medium, and large. The sizes

stated in the seed key represent the sizes most commonly found, but

allowance should be made for natural variation when the individual

seed is considered.

KEY TO THE SEED GROUPS

Seed surface roughened. . ^ ,

Group I. Seeds yellow, scar in shallow indentation at or near one ena.

Group II. Seeds light to dark greenish yeUow.

Seed surface smooth. .^^,0/^.-1

Group III. Seeds smaU, length 1% to IVs mm., width % to 1 mm

Group IV. Seeds intermediate, length 11/2 to 2 mm., width 1% to 1% mm.

Group V. Seeds large, length 2i^ to 3 mm., width 2 to 2% mm.

SEED KEY

Group I—

a. Tubercles very fine, not close-spaced, the minute projections usually

evident at the periphery ; seeds mostly heart-shaped, occasionally oval.

T, cernuum, drooping-flowered clover (pi. XXI, 420).

&. Tubercles very fine, more numerous than in T, cernuum but flatter,

the projections not evident at the periphery; seeds broadly oval;

occasionally somewhat pointed below the scar.

T. glomeratum, cluster clover (pi. XXI, 419).

c. Tubercles more prominent than above, the projections distinct at the

periphery; seeds heart-shaped or oval.

T. parvifiormn, teasel clover (pi. XXI, 423).

Group II—

a. Broadly oblong, somewhat warped in T. angulatum.

Scar in shallow indentation at one end ; very minutely roughened ;

length 11/2 mm., width 1 mm.

T. angulatum, crooked clover (pi. XXI, 418).

Scar in distinct notch at one end; tubercles large, wartlike;

length 2 mm., width IVs mm.

T. depauperatum, poverty clover (pi. XXi, 424).

I) Broadly oval, a marked depression between radicle and cotyledons;

tubercles minute, flattened, not evident at the periphery ; scar in a

sharp notch at one end ; length and width about equal, 1 to ly^ mm.

T, carolinianum, Carolina clover (pi. XXI, 422).

G Broadly oval, thick, a dark line between radicle and cotyledons but

not a distinct depression ; tubercles distinct, flattened, not evident at

the periphery ; scar in shallow indentation at one end ; length 1% mm.,

width iy2 mm T. refiexum, buffalo clover (pi. XXI, 421).

Group III—

a. Glossy, light yellow to brownish ; scar near one end, scarcely indented.

Broadly oval, somewhat rotund.

T. duUum, suckling clover (pi. XXI, 427).

Narrowly oval, flatter and more pointed than T. duUum.

T. procumhens, large hop clover (pi. XXI, 428).

Ô. DuU, oval to ovate ; scar near one end, scarcely indented.

Deep yellow at scar end, greenish below.

T. agrarium, hop clover (pi. XXI, 42o).

Light yellow to brownish.

T. nigrescens, ball clover (pi. XXI, 430).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 253

c. Dull, broadly oval, rotund, yellowish green ; scar in shallow indentation

near one end T. arvense, rabbit-foot clover (pi. XXI, 426).

Group IV—

a. Yellowish to brownish yellow.

Heart-shaped, flattened, dull; scar in shallow indentation between

the lobes at the broader end; length 1% to IV2 mm., width 1

to 1% mm T. repens, white clover (pi. XXI, 432).

Broadly oval, rotund, slightly glossy, minute whitish stipples evident beneath the semitranslucent seed surface; scar near one

end, scarcely indented ; length 2 mm., width 1% mm.

T, striatum, striate clover (pi. XXI, 433).

&. Yellow shading to purple toward the broader end, to almost entirely

purple or entirely yellow; seeds ovate, flattened, lustrous; scar in

broad, shallow notch or indentation near the narrower end; length

2% to 23/2 mm., width 11/2 to 1% mm.

T. pratense^ red clover (pi. XXI, 431).

G. Pale to dark rose-purple, dull, partially adhering whitish tissue produces a minutely veiny effect; roughly oblong and angular; scar in

a slight indentation near one end ; length 2 mm., width 1% mm.

T. lappaceum, lappa clover (pi. XXI, 429).

d. Light to dark olive green, occasionally deep yellow, glossy; ovate,

rotund; scar at the broader end at the base of a small projection,

pointed toward opposite end; length li/^ to 1% mm., width ly^ mm.

or more T, resupinatum, Persian clover (pi. XXI, 435).

e. Yellowish brown, dull ; oval, flatter than T. resupinatum; scar in shallow indentation at one end or below, projection at end of scar lacking; the opposite end not pointed; length 1% to 1% mm., width

1% mm. or more.

T. michelianum, big-flowered clover (pi. XXI, 434).

f. Variously streaked or mottled with black or dark green; glossy.

Roughly heart-shaped but variously compressed and obtusely angular ; yellowish to light reddish brown, finely spotted with black ;

scar in fine notch, off-center at the broader end; length I14 mm.,

width 114 mm.

T, ornithopodioides, no common name (not illus.).

Symmetrically oval; yellowish and sparingly or copiously stippled

or flecked with black, occasional seed not mottled ; scar in shallow

indentation at one end; length 2 mm., width 1% mm.

r. tridentatum, tomcat clover (pi. XXII, 442).

g. Variously streaked or mottled with black or dark green ; dull or lustrous.

aa. Broadly to narrowly heart-shaped ; scar in shallow indentation

at the broader end (a distinct notch in T. wUdenovii).

Bright yellow with small black flecks, especially on lower

portion, with a white line below the scar ; seed in bulk has

yellowish aspect; length 2 mm., width 1% mm.

T, fragiferum, strawberry clover (pi. XXII, 437).

Yellowish or grayish brown and copiously spotted with black,

seed appears almost black; length 2 mm., width 1% mm.

T. variegatuntj wMtetip clover (pi. XXII, 443).

Yellowish or gray, copiously streaked and spotted with black

so seed appears almost black; length 1% to 1% mm., width

1V4^ to 1% mm.

T. wUdenovii, seaside clover (pi. XXII, 444).

Greenish, copiously mottled with dark green so that seed

appears alrUost black, occasional seeds dull green and not

mottled, white line below scar lacking or obscure in the

lighter seeds ; length 1% mm., width I14 mm.

T. hylridiim, alsike clover (pi. XXII, 439).
254 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

Ô&. Narrowly ovate; scar in indentation at one side, near the narrower end.

Greenish and obscurely stippled with black; length l^^ to

1% mm., width 1 mm.

T. microcephalum, small-headed clover (pi. XXII, 440).

Yellowish and copiously mottled with black, occasional seed

not mottled; chalaza above scar distinct; length 2 to 2%

mm., width li/4 mm.

T. Ufldum, pinole clover (pi. XXII, 436).

cc. Narrowly oblong or oval, radicle often forming an angle at the

base of the cotyledons ; scar in notch or indentation near one

endYellowish and obscurely streaked or finely spotted with black,

with a short white line below the scar ; length 2 to 21^4 mm.,

width 11/4 to 1% mm.

T, microdon, thimble clover (pi. XXII, 441).

Group V—

a. Yellow to brownish yellow.

aa. Shape oval.

Glossy, symmetrical, rotund, scarcely indented at the scar;

length 2% mm., width 2 mm.

T. incarnatum, crimson clover (pi. XXII, 448).

Dull, flattened, scar in broad indentation near one end;

length 3 mm., width 2 mm. or more.

T. amUguum, kura clover (pi. XXII, 445).

&&. Ovate, lustrous, scarcely flattened; scar in slight indentation

near the pointed end; the light-colored line below the scar

sharply curved inward below; length 2i^ to 3 mm., width

2 mm T. alexandrinum, berseem clover (pi. XXII, 446).

CG. Orbicular or broadly oval, rotund, dull ; scar in a slight indentation at one end or near it ; seed coat with a few short, longitudinal wrinkes at the top of the cotyledons ; length 2% mm.,

width 2Vé mm T. hirtum, rose clover (pi. XXII, 447).

dd. Broadly heart-shaped or ovate, flattened, dull ; scar in a broad,

shallow indentation near the broader end; length 2% mm.,

width 2 mm. or more.

T. medium, zigzag clover (pi. XXII, 449).

5. Yellowish or greenish variously streaked or mottled with purple or

black; broadly oval, flattened, glossy; scar in shallow indentation

near one end ; length 3 mm., width 2 mm. or more.

T. gracilentum, pin-point clover (pi, XXII, 438).

c. Black or nearly so ; orbicular or broadly oval, rotund, dull ; scar in

narrow notch or shallow indentation ; length 2% to 3 mm., width 2^^

to 2% mm T. sudterraneum, sub clover (pi. XXII, 450).

TRIGONELLA—TRIGONELLA

(PI. XXII, 451-452)

Seeds of the numerous species of Trigonella vary widely in size and

shape, as well as in surface character. Only one species, fenugreek,

is in limited cultivation in the United States. Other species are

sometimes found as incidental seeds with crop seeds of European or

Asiatic origin, one of which {T, polycerata) is described below.

TrigoneUa foenum-graecum^ fenugreek (pi. XXII, 451) : The seed

is oblong and slightly flattened, with a deep groove between the radicle

and cotyledons; length 5i/¿ to 6 mm., width 3 to 3i^ mm.; color light

grayish brown ; surface finely roughened by minute tubercles or short
TESTING AGRICULTURAL AND VEGETABLE SEEDS 255

raised lines; scar within a prominent notch well below one end on

the long axis of the seed. The seed has the characteristic odor of

fenugreek.

Trigonella polycerata^ no common name (j)l. XXII, 452) : The seed

is narrowly oblong, length 2 to 21^ mm., width 1 mm. or more, the

surface roughened by minute blisterlike elevations; scar position ^

in fenugreek. The seeds may occur with such crops as alfalfa or

black medic.

Trigonella ornithopodioides {Falcatula ornithopodioides) ^ (not

illus.) has been referred to Trifolium omithopodioides and is described under that genus. This seed may occur in white clover of

New Zealand origin.

VICIA—VETCH

(PI. XXII, 453-459; pi. XXIII, 460-466)

GENERAL DISTINGUISHING FEATURES

Fifteen species of vetch are of interest either as cultivated crops or

as incidental seeds occurring with them or with similar crops. The

species may be separated into two major groups by the position of the

chalaza, which is usually evident with a hand lens as a minute, darkcolored spot or protuberance on the seed surface. In one group the

chalaza is located on the back of the seed, opposite the scar, as on

plate XXII, 455. In the other group the chalaza is near one end of

the scar, as shown on plate XXIII, 463.

Four species are represented in the group having the chalaza on

the back ; Vicia pannonica^ Hungarian vetch ; V. lutea^ yellow vetch ;

F. melanops^ no common name; and F. hybrida^ no common name.

Of these four species, Hungarian vetch is the only one cultivated as

a crop in the United States. Seeds of the other three species may

occur in varying quantity as incidental seeds in importations of hairy

and common vetch. Although the size of seeds within a species may

vary considerably, seeds of these three species are markedly larger

than those of the other species under consideration. They may be

variously compressed so that they do not roll readily on a plane

surface, and the scars frequently appear to lie in an oblique position.

The chief distinguishing characters are the relative length, width,

and shape of the scar. There is, however, some intergrading of these

features and some seeds may be difficult to identify with certainty.

Eleven species are included in the group having the chalaza near

one end of the scar. The species listed below are cultivated crops:

Narrowleaf vetch, V. angustifolia; hairy vetch, F. villosa; smooth

vetch, F. villosa var. glabrescens; common vetch, F. sativa; wooUypod

vetch, F. dasycarpa; purple vetch, F. atTopurpwrea; and monantha

vetch, F. articulata.

Seeds of hairy vetch and its variety smooth vetch are very similar.

No way has been discovered whereby they could be distinguished.

Hairy vetch and wooUypod vetch may be distinguished chiefly by the

scar. As shown on plate XXIII, 465 and 466, the scar or hairy vetch

is flush with the seed surface; that of wooUypod vetch is depressed
256 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

at the edges. Seeds of the Auburn strain of wooUypod vetch appear

to be indistinguishable from common wooUypod.

Seeds of narrowleaf vetch average smaller than those of hairy vetch.

The seeds are lustrous and black, or greenish with dark mottling.

The black seeds may be distinguished from seeds of hairy vetch by

tlie more wedge-shaped, slightly depressed scar with a raised slit

down the center. The narrowleaf vetch having mottled seeds has

not been found in seed from other than American sources. Some

seeds of narrowleaf vetch appear to be indistinguishable from the

smaller seeds of common vetch.

Seed of common vetch is variable in size, form, and color. In some

lots the seeds may be large, slightly compressefi or angular, in others

nearly spherical and smaller. The color varies from cream to black,

brown, gray, or mottled, the surface appearing semipolished rather

than dull and velvety as in hairy vetch. Light seeds with dark scars

and dark seeds with light scars are not uncommon. The seed scar is

narrowly wedge-shaped, depressed at the edges, març.ns of the slit

down the center distinctly raised, sometimes the entire scar transversely convex. Three horticultural varieties are in general use at

the present time, the Willamette strain, Texas common, and Doark.

No attempt has been made to distinguish the seeds of these varieties.

Certain seeds of common vetch and narrowleaf vetch are very similar

and cannot be distinguished with certainty.

Five species in the group having the chalaza near the scar may

occur as weeds with cultivated vetches or other crops. As shown in

the illustrations and in thö seed key, three of these species, showy

vetch (F. grandißora)^ tiny vetch (F. hirsuta) ^ 2inà fourseed vetch

(F. tetrasperma) ^ have distinctive features whereby they can be

readily distinguished.

There are several species of vetch having long and narrow scars,

% to 3^ the circumference of the seed in length. Two species of this

group may occur incidentally with cultivated vetches : Bird vetch (F.

cracca) (pi. XXIII, 460) ; and American vetch (F. americana)^ not

illustrated. It has not been determined to what extent the two species

may be distinguished by seed character alone. Seed of American vetch

appears to average larger in size, the scar broader and expanded at

one end. Doubtless there are intergrading forms.

SEED KEY

A, Chalaza on the back, opposite the scar.

a. Scar approximately 4 mm. long, narrowly oblong.

Width 1^ to % mm., slightly depressed around the edge; seed

6 to 6% mm. long, variously compressed.

y. lutea, yellow vetch (pi. XXII, 457).

Width 1 mm. or more, flush with surface of seed or nearly so;

seed 41^ to 5 mm. long, slightly flattened.

y. melanops, no common name (pi. XXII, 456).

h. Scar approximately 2 mm. long, flush with surface of seed or nearly so.

Width % to % mm., narrowly oblong; seed 4 to 4% mm. long,

slightly flattened.

y. pannonica, Hungarian vetch (pi. XXII, 455).

Width 1^4 mm., oval; seed approximately 5 mm. long, slightly

flattened V. hybrida^ no common name (pi. XXII, 458).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 257

B. Chalaza near one end of the scar.

a. Seeds 2 to 2% mm. long ; reddish brown or lighter with dark mottling.

Spherical; scar narrowly oblong, length 1^4 mm., width % mm.

or less V. tetrasperma, fourseed vetch (pi. XXII, 454).

Lens-shaped; scar linear, length about % of the circumference of

seed, width less than i/^ mm., obscured by persisting stalklike

appendage F. hirsuta, tiny vetch (pi. XXII, 453).

&. Seeds 3 to 5 or 6 mm. long.

aa. Scar % the length of the circumference of seed, linear, with

a minute frill of white tissue around the margins ; seed lensshaped, reddish, faintly mottled, lustrous, 4 mm. long.

V. grandiflora, showy vetch (pi. XXIII, 461).

hh. Scar % to % the length of the circumference of seed, linear;

seed spherical.

Scar approximately % mm. wide; seed black, lustrous, 3 to

31/^ mm. long T. cracca, bird vetch (pL XXIII, 460).

Scar approximately % mm. wide, expanded at one end ; seed

dull, black or lighter and mottled, 3% to 4 mm. long.

V. americana, American vetch (not illus.)

cc. Scar less than % the length of circumference of seed.

aaa. Seeds mostly spherical, roll readily on a plane surface.

Scar oblong or ovate, flat, flush with surface of seed,

length 2 to 2i/^ mm., width % to % mm. ; seed dull

black, velvety, length 3% to 4 mm.

V. villosa, hairy vetch (pL XXIII, 465).

Scar wedge-shaped, depressed at the edges, with raised

slit down the center, length 2 mm., width at center

% mm. ; seed black and lustrous or greenish with dark

mottling, length 3% to 4 mm.

y. angustifoUa, narrowleaf vetch (pi. XXIII, 463-464).

&Ô&, Seeds somewhat flattened, do not roll readily.

Scar oblong or ovate, with a minute ridge around the

depressed margins, usually with a light-colored strip

along the groove down the center, length 2 mm.,

width % mm. ; seed dull black or brownish, sometimes obscurely mottled, length 4 to 5 mm.

V. dasycarpa, woollypod vetch (pi. XXIII, 466).

Scar narrowly wedge-shaped, depressed at the edges,

with a distinctly raised, light-colored slit down the

center, length 2% mm. or more, width % to % mm. ;

seed color variable, commonly reddish brown, semipolished, length 4 to 5 mm., variable.

y. sativa, common vetch (pi. XXIII, 462).

Gcc. Seeds lens-shaped or nearly so, 5 to 6 mm. long.

Scar linear or narrowly wedge-shaped, length 1% mm.,

width less than % mm.; seed light grayish brown,

variously streaked or mottled with black or dark

brown V, articulâta, monantha vetch (not illus.).

Scar linear, obscured by white corky tissue, length 3

mm., width less than i^ mm. ; seed dull black, velvety.

V.atropurpúrea, purple vetch (pi. XXII, 459).

VIGNA—COWPEA

(PL XXIII, 467-468)

There are many cultivated varieties of cowpeas (Vigna sinensis)^

the seeds differing widely in color, as well as in size. Colors may

range from creamy white, creamy white with a black or purplish area

around the scar, light yellowish brown to dark reddish or purplish
258 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

brown, black, or variously mottled. Brabham, a variety having mottled seeds, is shown in plate XXIII, 468. Seeds of the more important

varieties in common cultivation are described by Morse {S7). ^

In general, seeds of cowpeas are slightly flattened, in some varieties

almost cylindric; the shape may be oblong, oval, or obtusely angled

as in the variety Iron ; the surface is smooth, or with fine longitudinal

wrinkles, as in Blackeye pea. The most common size is about 6 mm.

long and 8 to 9 mm. wide, but some varieties are considerably smaller,

such as the variety Eice, for example.

The seed scar averages 2 to 3 mm. long, the width and shape varying

somewhat with the variety. The entire scar is depressed and obscured

by a persisting thick, corky tissue, which is elevated above the surface of the seed. The character of this appendage is an important

distinguishing feature of the species. As shown in the illustration,

the whitish inner portion is surrounded by a border of darker, usually

greenish, tissue. In some varieties, as in Iron, there is a light-colored

band around the scar, or there may be a saddle-shaped black area

around the scar as in Blackeye cowpea.

CONVOLVULACEAE (MORNING-GLORY FAMILY)

(PL XXVI-XXVII, 549-562)

The fruit of the morning-glory family is a globular two-^ to sixseeded capsule. The embryo of the seed, except in Gusmta^ is large

and curved or coiled in the endosperm. The cotyledons are broad,

thin, and much folded or convolute. The embryo of Cuscuta is spirally

coiled and without cotyledons. Seeds of the genera comprising the

family vary greatly in size, shape, and surface character, but the scar

area is fairly characteristic of the family. It appears as a more or

less well-defined, rounded or oval area near one end of the seed.

Four genera are of particular interest as field weeds: Cuscuta^

dodder; Ipomoea^ Convolvulus^ and Jaoquemontia^ the morningglories and bindweeds.

MORNING-GLORIES AND BINDWEED

SEED KEY

A. Scar area hemispheric or broadly oval, with a knoblike projection at either

end of the broad base of scar.

a. Surface roughened by fine tubercles or short wavy lines.

Dull grayish brown ; back side convex, lateral sides plane ; broadest

above the middle, length 4 to 4i^ mm. ^.^^r-r ^...^^ Convolvulus arvensis, bindweed (pi. XXVI, 549).

2). Surface smooth or minutely roughened.

Black ; back side convex, lateral sides plane, each with a large, oval

depression ; broadly oval ; length 5 to 6 mm. ; scar area prominent.

Convolvulus septum, hedge bindweed (pi. XXVI, 550).

c. Surface smooth, densely pubescent on the angles; length 7 to 8 inm.

Ipomoea pandurata, clustered blue morning-glory (pi. XXVI, 554).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 259

B. Scar area oblong or orbicular, with two minute linear projections close

together near the base of scar ; broadly oval ; length 5 to 6 mm.

a. Dull, light grayish brown.

aa. Scar with reddish brown, dense, coarse pubescence ; back side

rounded, with or without a slight depression down the center,

lateral sides plane with a distinct line around the outer

margin.

Ipomoea Tiederacea, ivyleaf morning-glory (pi. XXVI, 552).

ÔO. Scar relatively smooth ; back side rounded, with a broad, shallow

depression down the center, lateral sides flat or with obscure,

short transverse folds.

Ipomoea purpurea, common morning-glory (pi. XXVI, 553).

&. Semipolished, smooth and horny, black with brownish cast.

Scar smooth, larger than in hederacea and purpurea; back side

rounded, not evidently depressed down the center, lateral sides

plane with a distinct line around the margin.

Ipomoea lacunosa, small-flowered white morning-glory (not illus.).

C Scar area oblong, projections at base obscure or lacking; light brown, roughened by lighter brown blisterlike protuberances ; length 2% to 3 mm. ; back

side convex, lateral sides plane.

Jacquemontia tamnifolia, hairy morning-glory (pi. XXVI, 555).

CUSCUTA—DODDER

(PL XXVII, 556-562)

Seeds of dodder are characterized by a small distinct scar area

near one end of the seed, in the middle of which the hilum appears as

a raised line, point, or slit. The species are distinguishable chiefly

by size and shape, character of the hilum and scar area, and surface

texture.

The shape of the seed is largely determined by the number of seeds

developed in the capsule. Certain species regularly produce four

seeds, others one or two. In a four-seeded capsule the seed will have

two flattened inner surfaces and a convex outer surface, as in Cuscuta

flanißora. When only one or two seeds develop in a capsule the seeds

assume a more globular form, as in G, indecora. Size is helpful in

the determination of a small quantity of seed, but it is too variable in

some species to be entirely reliable in application to the individual

seeds. A list of characteristic features of seeds of seven species of

dodder follows.
260 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

List of Characteristic

Species Length Form Color

Cuscuta planiflora. Small- (Approx.) 1mm Uniformly oblong, distinctly angled.

Globose, occasional seeds

angled.

Broadly obovate, angled;

often stick together in

pairs.

Fairly uniform, rounded

or ovate; angles usually distinct.

Rounded or ovate, not

sharply angled.

Variable, mostly broader than long, not

sharply angled.

Ovate, tends to be less

angular than C. pentágona.

Uniformly yellowish or

with slight brownish

tinge.

Dull gray or brownish

gray; like particles of

earth.

Grayish white

seeded alfalfa dodder

(pi. XXVII, 556).

C, epithymum. Clover 3^ to 1 mm

dodder (pi. XXVII,

557).

C. epilinum. Flax dod- 1 to IJ^ mm _ ._

der (pi. XXVII, 558).

C. pentágona. Field 1 to IH mm Uniform dusty gray

with definite pinkish

cast.

Dull reddish brown,

fairly uniform.

Not uniform, light grayish brown, reddish to

dark brown.

Uniform reddish brown.

dodder (pi. XXVIl,

560).

C. racemosa var. chUiana

Chilean dodder (pi.

XXVII, 561).

C. indecora. Largeseeded alfalfa dodder

(pi. XXVII, 559).

C. gronovii. Common

(Approx.) l^^mm

1}4 mm. or longer __

1^ mm

dodder (pi. XXVII,

562).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 261

Features of Seeds of Dodder

Scar area Hi]um Surface Range

Indistinct A raised point Very finely rugose with Widely distributed in

tendency to reticula- Western States, Washtions. ington to Mexico.

Indistinct A short whitish line Coarsely granular, somewhat pitted.

Widespread throughout

North America.

Distinct, flat, finely

striate radially.

A raised point Coarsely scurfy. _ - In flax sections of the

Northwest.

Distinct, flat, "finely A raised white line Finely scurfy, smooth- Widely distributed in

striate radially. est of the species considered.

the U. S.

Distinct, large, usually A short slit or depressed Slightly rougher than Scattered across contioutlined with light point. C. pentágona. nent; mostly in alfalfa

rim, radial striâtions areas.

faint or lacking.

Indistinct, slightly A short slit in the de- Coarsely scurfy, rugose. Common in alfalfa resunken, margins more pression at center. bordering on reticula- gions of the Western

or less obscured by tions. States.

scurfy epidermal

tissue.

Distinct, flat, finely A short slit or whitish Evenly and finely scurfy; Widespread throughout

striate, margins often line, not raised as in coarser than C. pen- eastern North America.

outlined with light C. pentágona. tágona; smoother than

scurfy tissue. C. indecora.
262 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

ILLUSTRATIONS OF CROP AND WEED SEEDS

(Pis. I-XXXIV)

Gramineae (pis. I-XII).

Cyperaceae (pi. XII).

Commelinaceae (pL XII).

Juncaceae (pi. XII).

Liliaceae (pi. XIII).

Iridaceae (pi. XIII).

Cannabinaceae (pi. XIII).

Urticaceae (pi. XIII).

Polygonaceae (pis. XIII-XIV).

Chenopodiaceae (pi. XIV).

Amaranthaceae (pis. XIV~XV).

Nyctaginaceae (pi. XV).

Aizoaceae (pi. XV).

Portulacaceae (pi. XV).

Caryophyllaceae (pis. XV-XVI).

Eanunculaceae (pi. XVI).

Papaveraceae (pi. XVI).

Fumariaceae (pi. XVI).

Cruciferae (pis. XVI-XVIH).

Resedaceae (pi. XVIII).

Rosaceae (pi. XVIII).

Leguminosae (pis. XVIIIXXIII).

Geraniaceae (pi. XXIII).

Oxalidaceae (pi. XXIII).

Linaceae (pi. XXIII).

Zygophyllaceae (pi. XXIII).

E u p h o r b i ace ae (pis. XXIIIXXIV).

Malvaceae (pi. XXIV).

Sterculiaceae (pi. XXIV).

Hypericaceae (pi. XXIV).

Violaceae (pi. XXIV).

Loasaceae (pis. XXIV-XXV).

Lythraceae (pi. XXV).

Onagraceae (pi. XXV).

Umbelliferae (pis. XXVXXVI).

Primulaceae (pi. XXVI).

Apocynaceae (pi. XXVI).

Asclepiadaceae (pi. XXVI).

Convolvulaceae (pis. XXVIXXVII).

Polemoniaceae (pi. XXVII).

Hydrophyllaceae (pi. XXVII).

Boraginaceae (pis. XXVIIXXVIII).

Verbenaceae (pi. XXVIII).

Labiatae (pis. XXVIII-XXIX).

Solanaceae (pi. XXIX).

Scrophulariaceae (pis. XXIXXXX).

Pedaliaceae (pi. XXX).

Plantaginaceae (pi. XXX).

Eubiaceae (pi. XXX).

Caprifoliaceae (pi. XXX).

Valerianaceae (pi. XXXI).

Dipsacaceae (pi. XXXI).

Campanulaceae (pi. XXXI).

Lobeliaceae (pi. XXXI).

Compositae (pi. XXXIXXXIV).
Agriculture Handbook No. 30. U. S. Dept. o( Agriculture PLATE I

(iniininrae (1 i;4 i

1. Ai]ntnti>i idhil U. A(/roi>!tioii ri'in'Hf

2. Ayrofttix leuuh 10. Agropifton .''mitliii

¡i. Affrosti-f cxarata 11. A tji-ftiniidli tra< Intcaiiliim

i. Áyroíitis cj-arata I'J. A ¡;roil!/>'<)» elotiita t » m

5. AgroHtix canina i:;. Atiro¡)!iri>n eristat um

(!. Aíiroxti« clliottiaiia 14. Afjioiii/roii (Ir.^rrtitnnn

7. A(jrosth hi€maH>i IT). A(/roinfr/nt int frm vâi u m

8. Af/roHtiK xcahra Hi. A f)ri)[turan trirh Ojfh iirtt m

1 7. Aira rh'<jan.s

18. Aira niryofthyllea

11). Ah)f)frunts aeqiiaUx

20. Ah/i>r<uni'< caroUnifunts

21. Alftitrcurns geniculatus

22. Alofjcrurus /trntetiiiix

2;î. Aloftrrunis myoHuroidea

24. Ariíitián dichotomn
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE I I

\äi-^.-»»^ ^lï V*»6V

Gramineae (25-48)

25. Aiídropogon yerardi (A. 33. Antboxanthum odoratum

furent US) 34. Apera spíea-venti

26. Andropogon haUii 35. Arrhenatherum elotius

27. Andropogon ftcopnríuK 3f,. Avena sátira

28. Andropogon ischaemum 37. Arena htizantinn

29. Andropogon intermedius 38. Arena (homozyi?ous fatu30. Andropogon nodosus oi(l)

31. Andropogon sericeuít 3». Aren/l fatua

32. Andropogon virginicufí 40. Arena harhata

41. Avena (ttrigosn

42. Axonopu^t a/finis

4.'i. AJconopuH compressas

44. Berkmannia syzigachne

45. Bufhloë dactyloides

46. fíouteloua curtipendula

47. Bonteloua gracíHs

48. fíouteloua hirsuta
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE 1 II

Grainliieac (40-72)

49. Hromim tectnriim

rio Hrtimun »terilin nil

r>i fíromuK jaiMiiivux i;ii

52. BromtiHctiinwitlutHft (¡1

r>:i Hrumttft necuUnuti <i2

r>4. Uromiix molli» «:!

fir> HromiiH inermU •i4

.")«. liromiin cnthartifu» (•>->

57. HromHs maríjinatn-s

»8. Chforiít ilirnricata *>7.

Chloria (tcicularis 08.

(^hloris ffdifaua

(Î1. Cotf/nei>hon ranefiCfUfi *íí».

Cynodon tÎijctyJmx 7**.

Cvnrhius /Kiiir'tftorux 71.

IhfnuHiirus crixtatus 72.

(îr>. difiioxurits t'lrhinatiifi

(Hi. Dnviylls ffloimrata

Oanthonin xpicnfa

l>authonia ti/>irata (CU'is

l>rsihami)xi(i (Uiexftitosa

OistirhHx stricto

JUstivhlis s¡iirnta .
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE IV

7."!. Diffitaria fififonnh

74. hiffitariii iftchnftnum ,

75. Diffitariii ininguittalix

7(i. EchinochJna colonum

77. Echinovhloa crungaUi

78. Erhinochbin rrtisgaHi

var. frumrntarfft

70. Elcuxinc coravfinn

80. Elciisiue indien

Gramineae Í7;í'90í

81. IJlf/muK canadvnsis UO.

82. A7f/wiH.v !/lnm-ux *M.

s:\. KJ'f/mus jiinccus i»2.

84. Eiymux rirginirus it;!.

85. Etagrostis capiJiaris 94.

8H. Eraffrostis vilianensia 95.

87. EragroNtia (hloromvlas î»6.

88. EragrofitiH curruîa

89. Eragrofttifi Ichmatniiana

Erngruxfin trichodes

Eremochloa oithiuroifienEriovhloii punctata

Fetttucu rintior

Fextticn nnittdiiKfCea

Eefitt4ca ruhra

Festuca myiiros
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE V

Graniineae (97-l:iO)

97. Oastridium ventricoaum

98. Gluceria flititans

99. Gluceria grandin

100. Gîyceria striata

101. Hackeïochloa granitlarls

102. Holcus lanatUH

lOH. Holcus mollin

104. HordeuM rulfjare

105. Hordeuni fiuiiillum

lOG. Hordeum brachgantheru m

107. Hordeum juhattnn

108. Hurdcum Ic/torimtm

(H. murinum I

109. Le/itoloma vognatum

110. folium fH'rcnnc

111. Lolium multiflorum

112. Loiium /tcr^icum

11 .'i. Lolium tern nlcn tu m

114. Melinitt minutifíora

115. Molinia caerulfu

110. NaHNt'Ua trichotoma

117. Ori/:^« sátira

118. Orf/zopsÎK hjfmcnoidcH

119. OrifzopHïx miliaven

120. Phleum liratcusf
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE VI

Gramineae (121-138)

121. Panicum ance¡}s

122. Panicum antidotale

123. Panicum bergii

124. Panicum^ hrachyanthiim,

125. Panicum capillare

126. Panicum capillare var.

uccidentaU'

127. Panicum dichotomiflorum

128. Panicum fasciculatum

129. Panicum gattingeri

130. Panicum hillmani

131. Panicum hnachuc^ac

132. Panicum maximum

133. Panicum mili<tceum

134. Panicum obtusum

135. Panicum purpurasoens

136. Panicum ramosum

137. Panicum texanum

138. Panicum riryatum
Agriculture Handbook No. 30. U. S. Dept. oí Agriculture PLATE VII

GranUneae (139-158)

i:V,i. Pa>fp(tUim hoxfinnum

140. PfiKpnlum fiilatdtttm

141. Pnx}i<ilum iiisHchitm

142. Pftí*¡)alum florida»um

143. PfiMfifthnn hiere

144. Pn'<¡ni}um infiUirofthifl'

1 u m

14.'. Pa xf) a 1 u m n o tat u m

146 PditpaJum ¡tlicatiilutn 154.

147. Pn--<f>alum setareum

148. Paf<¡KiJum iirrillei 155.

149. PeiinisctHtn glaurum 15*}.

15(t. Pnuti>!etum ¡nn'tiurrum 157.

151. PhaJari.\ nngustn 158.

152. Phniaris aruntWnncca

153. Pholnriii minor

Phaîaris tuheroitít var.

t<tenoptern

Phalariti canarienifix

Phalarix /»aratloxa

Poîi/poffou mouftpelienffis

Schefloniiardii.s pnnirulatns
Agriculture Handbook No. 30. U. S. Dept. oí Agriculture PLATE VIM

Gramiiií-aH (159-l*i4í

159. Pon ünnun

160. Poa a m ¡tía

IBl. Poa nravhniffm

162. Poa árida

ItÍH. Pon bulbosa

104. Poa vomitr€S>*a
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE IX

J&ä.

,Ä m

,1;'

; í

m

167 ^ ^'^ y" i 68

C

1<)5. A*«« interior

Ifífi. /'on ¡irmuriilis

(ininiincaf (l()3-170l

lt)7. /'«(! luidilcnxiK

lOK. i"«« iialuHtrin

IHO. Pon ¡¡ratmniK

170. /'ort triiialis
Agriculture Handbook No. 30, U. S. Dept. of Agriculture PUATE X

Gramineae (171-1791

171. /'na spp. Shape a lUl ) P. secun(ia 172. Setaria faberi

pu bcso'nce of pa le is. k. P nevadensis 173. Setaria geniculata

H. /• ¡jratenniíf 1. P. ampia 174. Setaria grisebachii !>. P. îrii'iaîiii m I . canbi/i 175. Setaria lutescen^

V. P nemoralis ». P eiisickii 176. Setaria mavrustachya rf. P compresiva 0. P. ylaucifoUn 177. Setaria magna

p. P. paluKtri« P P interior 17S. Setaria rerticiUata

f- P. aruí'hnifvra II- P. Ittnyilit/iila 1711. Setaria riricHn

li- P ü riil a y. P. fendleriana

li

i.

P

P.

anitun

jiincijolia

K. P. /ftenantha
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XI

(ininiiiieae (180-l!»öi

180 cetaria italien lOmi- 18(i. KorijUum liKlnneiiíie Uli", sorghum ntlíinrc ( HPniutl I 187. Sor<ilniin~Siiiliiii hylii'idii «ari)

181 fetaria itnliru i Hun- 188. .Sv„¡//i KM iidi/nrc ( Black in:i. Soruhum lulgarr (Feteearian) AIUIMT) rita I

IS" SHnrin itnliai iGer- 180. Son/hum riitgarp (Su- 1!)4. S o r p h ii m v u ¡ ga r e

man I mac) i Brnomcorn i

183. setaria italien (White lOi). .'-v,r.f//iH»i ii/ííKire (Mil" i litó, stiiia rimliiia

Wcmder) lili. l<firgliiim rulgarr

18-t. Serale cereale (Kafirl

185. Sorghum halepenne
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XI I

Gramineae (l!)6-203)

196. SiKJTobolu» clitndestinuK

197. kpoioholuH cryiitandru«

198. Sßorohuluis mglectu«

199. Tridens flaius

200. Trisetiim flaveaienn

201. Triticum aestivum

202. ZoiiHia japónica

203. Zoyttia matreUa

204. Carex fentuearca

Cjlieraceae (204-214), Conimelinnceae (215-216),

Junoaccac (217-219)

Carejc tncfiocar/ia

Vyperus esculetttuN

Cypet'Hs rotundus

Eteofharis ohtutta

KleochariH lemiia

^iu. FinihrUtfiHn atitumnall

211. FiinbiiKti/lin haldiriniana

Kullinija sp.

205,

206,

207

208,

209

210

212.

21.3. Rhutwhoiitoiii mniraatachyu

214. ticir/ma si).

215. Cotnmelina communis

216. Tradescantia virginiana

217. Luzula campestris

218. Ijiizula luzuloides

219. Juncus tvHuis
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XMI

236 j,3^ ^0

^

Liliaceae (220-223), Iridaceae (224). Cannabinaceae (225), Urticaceae (226),

Polygonaceae (227-248)

220. Allium vineale

221. Brodiaea coronaria

222. Brodiaea grandiflora

223. Muscari comositm

224. Sisyrinchium sp.

225. Cannabis sátira

226. L'ríica dioica

227. Polygonum argyrocoleon

22K. Polygonum aviculare

229. Polygonum ariculare

(Cleistogenes)

230. Polifgonum conrolrulus

231. Polygonum hydroiñper

232. Polygonum I a ¡t a t h ifolium

233. Polygonum persicaria

234. Polygonum pensylranicum

235. Humex acetosa

236. Rume^ acctosella

237. Rumcx altissimus

238. Rumex conglom^eratus

239. Rumex crispus

24(1. Rumex olitusifolius

241. Rumex ocridentali»

242. Rumex persicarioides

243. Rumex pulcher
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XIV

Polygonaceae (244-24.51. Chenoportiaceae (246-2661. Aniaranthaceae (2671

244. Hiimejc KaVtHtoUiiK 254.

245. Rumrj- veno^u^ 255.

246. A trilit ex patilla var. ?i««-

tata 256.

247. Atriplcjc rovi'a

248. AtTifßU'T trunrata 257.

249. Aj-f/riM amaratithoitles 258.

250. Bnf<f<ia hi/í^ííopi/olia 259.

251. Vhenopoiliuin album

252. Clicn'iitoflium herían- 260.

tticri 261.

2.5.3. Chenopodiu m h ircin ti m

Chrno1)0(1 ium h ifbriflum 2*;2. Suoeda tieprcH^^a {DottChfuoftodiiim hi/hridum (lia tlrpreana)

var. {/igantosfjcrmum 2<>:i. Halogeton gJomeratus

Vhvnff})0(í\um lepto- 2*14. Kochia ficoparia

¡ihyUum 205. Roubirru multifitia

('henoi)O(Iium murale 2tîn. S'aÎMoin kiiJi var. tenuiChenOfiodium ruhrum fnlia

Coritpermum hyi*xoi)Í- 207. n. Amarnnthux retrofolium fifxus

Cohiipermum villosum h. Awarauthufi nUiu>i

CyfUiloma atripUciffj 1 i u m
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XV

276 _'.-:-^1 4^Bl

278

X7I/E

279 ^,

X7(/2

Amaranthaceae i268). Xyctaginaceae i:2ti9-270l. Aizoaceap (2711.

Portulacaoeae (272i. Cnr.vophyllaceae (27.3-291)

268.

269.

270.

271.

273.

274.

27.5.

AmoranthHx graeoizann 276.

(.l. Mitoidest 277.

Boerhauiin erecta 278.

Mirahilis uyctaglnea 279.

(AUioniti nyctagineii) 280.

Trianthemii portulaca^- 281.

trum 282.

Portiitaca olerneeti 283.

Agrostemmti githatfo 284.

Sfeliari/t graminea

Stellnrin media

Arenaría neritylUfoUa 285.

Ceratttiitm' vitlgatam 286.

D'uinthaH armería 2S7.

Litehníí^ alba 2S.s.

Lychnis dioica

Sa/ionaria varearía 289.

Scieranthas annuuí<

fiilene antirrhina 290.

Silène gallien (S. n«- 291. ííileiie noctíflora

glíca )

Silène cónica

Silène conoidea

Silène (Tetica

Silène cierei

haría)

Silène cuciibaliis

lati}olia\

Silène dicliofonia

iS. fais.
Agriculture Handbook No. 30, U. S. Dcpt. o( Agriculture PLATE XVI

ff Ai ft

292 293

294

BS^ ^Ê9 fl^'

^^é 302è lí^

vlgr

303 •

306 ^\^m <s 307

XIO

309 311

MM

312 313 314

Caryophyllaceae (292-293), Ranuncnlaceae (294—^04). Papaveraceae (:i()5-308),

Fumariaceae (•!(t9), Crucifcrac |31<>-H15)

292. ^pérgula arrensin 301.

293. iiypergula pfntandra 302.

294. Anemone vanndensis 3*13.

295. Delphinium consolida

296. Delphinium mt^nziesii 'M)4.

297. Nigella damescenn .'Î05.

298. Nigella nativa

299. Ranunculus acrift 306.

300. Ranunculus hulhosus 307.

Ranunculus parviftorus 308.

Ranunculus repens ."¡09.

Ranunculus surdons (R. 310.

parrains) 311.

Thalictrum sp. 312.

Knchscholtzitt califor- 313.

Hif-rt 314.

Glauvium corniculatum 315.

Papaver somnifcrum

Rocmeria refracta

Fumaria officinalis

Alpssum alffssoidcH

Arahis glabra

liarharea rema

íiarbarea vulgaris

lierteroa incana

Rrassica campestri»
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XVM

••«• HÊ&9

€•;:•=# \^ 0

329

:?i .in *

Cruciferae (316-339)

316. Brassica júncea 324.

317. Brasêica kaher (B. ar- 325.

ren.sts) 326.

318. Brassica napus var. 327.

biennia 328.

319. Brnssica nigra

320. Camelina microcarpa 329.

321. Oameiina sattro

322. Cardaría draba 330.

323. Cardaría pubeacens

(Hymenophysa pubes- 331.

cena) 332.

Chorinpora tenella

Conringia Orientalis

Eruca sativa

Erysimum asperum

Erysimum ch ei^r a nthoides

Erysimum inconspicuum

(E. parvifiorum)

Hirschfeldia i n c an a

i Brassica adpressa )

Lepidium campestre

Lepidium densifiorum

333. Lepidium latifolium

334. Lepidium rirginicum

335. Neslia paniculata

336. Raphanus raphanistrum

337. Raphanus sátiras

338. Rapistrum rugosum

339. Rorippa austríaca
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XVI 11

340

fJ

344 • «

•I

#.#

352

I

•0:

il im

356

0): #

xs

XI xs

XI

.)<••• 361

Cnioiforae (340-344), Resediioeae (345). Rosaeeae (340-352). Lojíuminosao (353-3(i3)

:\4{). Rorippa RUlrentriH

341. Sisjfmhrium altinsimum

342. tiisf/mhrium officinale

343. TevsdnÎia nndivanUa

344. Thlaxfii arreiiiie

345. Rvsrtla lutcn

340. fíeiim Kp.

347. Potentilla canndensix

348. Potentilla monspeliensis

349. KoA'fl sp.

350. Rubni< sp.

351. i^anguisorho annua

352. Sanffuisorha minor

353. .4íf('.Hmía mu-rtrai«

35(!. -tli/sicarpun raf/itt(ili.s

357. Anthi/IUs ruineraria

358. AstraffttluH chinensis

;'5it. Afttrof/alus cievr

300. Antra(foluH falratun

301. Astniffalufi pexuosus

354. Aesrhynomene rirginiv» 302. Atitrngalus imttntliiinuft

.'Í55. AUiagi pneutlalhagi .">03. A>itragtilus nihi/i
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XIX

XI 1/2

367

111

368'

X2lA

."¡(U. Cn,«-vi(! nictitans

.H65. Cnssin iorn

HB6. Cicer arietinum

S67. Coronilla «poi/doirfe.«

3t>8. Coronilla raria

.•'.()9. Crotalaria intermedia

370. Crotalaria lanreolata

.H71. Crotalaria mueriinata

If. utriata)

Leiruminosae (H64—:í87)

;í72. Crotalaria speettlhiíiH

MS. Ci/ainoi>«is tetragonolo

'Mi. Diiubentonia tvxana

;í75. Deftmodium tortiiosum

376. Galega oyT'cí«"'''«

377. Gllieiite max

.37S. Hedilxariim eoronariiim

\~',). lloffmaiihHefigia xp.

380. /iidiffofera hirsuta

.381. iMthiiriix aiihttca

382. I.atlniniK hirsutus

3,s:!. l.athDriin .v»ii(»fr/.v

3S4. I,a til.uni.'' tini/itnniiK

385. I,atliijrii.t taherosuK

38ti. Lc-^pedeza utriata

387. Ijrsjiedeza .^triatn

lKi>l)i')
Agriculture Handbo<^k Nn. 30. U. S. Dcpt. of Agriculture PLATE XX

«92 •

394" 395

40S

H88. Lesftvdrzn stipulacen

:í89. L€S})V(U'::n cmivata

H90. Lotus anuustiNsimHft

H91. LotuH corn iruht tu.H

H92. Lotus his/tidus

'Ad'S. Lotus purnhinnus {L.

ameri(-anus) ,'Í94. Lotus ulifjinosus var. 401. Afedicago orhicuïaris

.villosHs 402. Medivof/o sntira

Lf^niiiiiiosap (38S-411>

;i95. Lotufi uliyinoxus var.

:í9(í. Lupiiius augustifolius

.'i!i7. Lufiiuus luteuK

;!98. Medivuifo arahicn

:i!)y. Medicdffo his/tida

400. MedUayo lupulina

A0'.\. Medkagü tuhcrculata

404. A/füioíi/s ai&rt

405. Melilutus officinaïis

406. Melilotus indica

407. Onohrychift riciaefoha

408. Ouonis repens

409. Onùthopus sntivuH

410. Phaneolus atigniaris

411. PhasfoluM aurcus
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XXI

XI1/2

1% ^f

XT I/I

X5 X7I/2

XI XI

424

428

XT 1/2

«0 429

XT(/2 '^9 ft fP: ?i^

^^ 432 00 r«" .433.-

•

W

434

412. Pisum stttirum var. arreuse

413. Piierarht thunhergiana

414. Setbania exaltttta

415. Stizolohium deeringianum

416. Sliophoatliles I e i o sperma (S. ¡laueipora)

417. Hvxiinsona saUula

Leirmiiiiiosat' 1412 4:10 )

418. TrifoUiiin' aniiiihitiim

419. Trifijlhim nlomcratiim

420. Trifoliiim lernuum

421. Trifoliiiin ¡etlextim

422. Trifvliuiii carotininnuiii

423. Tiifnliiim iiiiriifliinim

424. TrifoUum ileiiiiuireratiim

425. Tri.fiiJiiim ai/raiium

426. Trifoliiim nrrcnxe

« «

427. TrifoUum iliihiiim

42S. Trifoliiim ¡irociimhenx

42SI. TrifoUum lai>i>aeemn

4:i(l. TrifoUum nigrrscens

431. TrifoUum prntense

432. TrifoUum repen s

433. TrifoUum striatum

434. TrifoUum michelianum

433. TrifoUum resupintttum
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XXII

XTI/t

^

437

V*

ié' «r Jd • " 04 ©ft

tF^ ^Ml 443 "»^

' KJ

44Í

448

0©° Ö§

f , X? |^449|-^", 45(

•I

«Zt/^ if''^457_

4;ítí. Trifoliuni hifíúum

4H7. Trifolium frnyiffrum

4i^8. Trifolium grncilvntiim

439. Trifolium hybridum

440. Trifolium microcephalum

441. Trifolium microdon

442. Trifolium iridentat urn

443. Trifolium rariegatiim

Lexiiinlnosa*' (436-459)

444. Trifolium uiUlenorii

44"). Trifolium ambifjuum

44ti. Trifolium alcxandrinum

447. Trifolium hirtum

448. Trifolium incarnat urn

449. Trifolium medium

-i~U). Trifolium ttubterraneum

451. Trigonelltt fornum-graecum

452. Triffondln /lolffccrafa

453. ricia hirsuta

454. l'K-iíi tetrasperma

455. Vtcía pannonica

45(i. Fícírt mclanops

457. F/rin iufR«

458. Virin hf/brida

459. rící« atropurpúrea
Agriculture Handbodc No. 30. U. S. Dept. of Agriculture PLATE XXIII

ff: o'oß i

Q| •••• f^ ::^

468

472 473 474

Leguminosae (460-468), Geraniaceae (469-474), Oxalidaceae (475), Linaceae (476-477),

Zysophyllacpftc M78), Euphorbiaceae (479-483)

460. Vicia cracca 468.

461. Vicia grandiflora

462. Vicia sativa 469.

463. Vicia angustifolia 470.

464. Vicia angustifolia 471.

465. Vicia villosa 472.

466. Vicia dasycarpa 473.

467. Vigna »inenais (Black- 474.

eye) 475.

Vigna »inensiè (Brab 476.

ham) 477.

Erodium cicutarium 478.

Geranium carolinianum 479.

Geranium columbinum 480.

Geranium dissectum 481.

Geranium molle 482.

Geranium pusillum 483.

Oxalis stricta

Linum usitatissimum

Linum virginianum

Tribulus terrestris

Acalypha. virginica

Crotón 8p.

Eremocarpua setigerus

Euphorbia coroUata

Euphorbia es'ula
Agriculture Handbook No, 30, U. S. Dept. of Agriculture PLATE XXIV

488 489 ••a 49g ^^^ l^é,,, *f a

£|498-

501 «BE

502

504

X7 1/2

505

506

507

Euphorblaceae (484-488), Malvaceae (489-502), StereuUaeeae (503), Hypericaeeae (504),

Violaceae (505), Loasaceae (506-507)

484. Euphorbia denlata

485. EuphorMa helioncopla

486. Euphorbia marginata

487. Euphorbia nutann

488. Euphorbia supina

489. Abutilón theophrmti

490. Althaea hirsuta

491. Hibiscus trionum

492. J/aii;o moschata

493. Afrailo parviflora

494. Malta rotundifolia

495. Malva sylvestris

496. Malrastrum coromandelianum

497. Sido hederacea

498. Sida spitwsa

499. Sidalcea campestris

500. Sidoicen hendersonii

501. Sidopsis hispida

502. Sphaeralcea coccinea

503. J/eiochio corchorifolia

504. Hypericum perforatum

505. Viola tricolor

506. Mentzelia albicaulis

507. Mentzelia dispersa
Agriculture Handbook No. 30. U. S. Dept. of Agriculture PLATE XXV

>28á^ '•^H 2ta^

Loasaceae (508). Lythraceae (509). Onagraceae (510-520), Umbolliferae (521-531)

508. Mentzelia nuda 518.

509. Lythrum hyftsopifolia 519.

510. Boisduvalia densiftora

511. Boisdu valia Htricta 520.

512. Gaura coccínea 521,

513. Gaura odorata 522.

514. Gaura ttinuata 523.

515. Oaura villosa 524.

516. Godftia tenella 525.

517. Ludtcigia altemifolia 526.

Oenothera biennis

Oenoihera laciniata

(Raimannia laiiniata)

Oenothera parodiana

Aethuaa cynapium

Ammi majutt

Ammi visnaga

AnthriftcuH sylreatrin

Apium ammi

Apium segetum

527. Bunium bUlbocastrum

iC a r u m bulboca>itrum)

528. Bupleurum protractum

529. Bupleurum rotundifolium

530. Bupleurum tenutssimum

531. Carum carvi
Agriculture Handbook No. 30, U. S. Dept. of Agriculture PLATE XXVI

552

Umbelliferae (532-540), Primulaceae (541). Apocynaceae (542-543),

Aselepiadaeeae (544-548), Convoivulaoeae (549-555)

532. Chaerophyllum sp,

533. Cicuta maculata

5H4.' Conium maculatum

535. Daucus carota

536. Falcaría ririni

537. Petroselinum hortense

(P. crispum)

538. Pim¡)inclla saxífraga

539. TorilÍH anthriscus

540. Torílis nodosa 548.

541. Anagallis arcensis 549.

542. Apocynum andromisae- 550.

folium 551.

543. Apocynum cannabínum 552.

544. Asclepias mexicana 553.

545. Asclepias galioideti 554.

546. Asclepias syriaca 555.

547. Asclepias tuberosa

Gonolobus laevis

Convolvulus arvensiß

Coni'olvulus septum

Dichondra repens

Ipomoea hederaceo

Ipomoea purpurea

Ipomoea pandurata

JacQuemontia tamnifolia
Agriculture Handbook No. 30, U. S. Dept. of Agriculture PLATE XXVI I

RR7 s«;« 559 ^i^ * 556

560 561 ^ IP • ^, 5"

j66~ ^>^ 567

576

577

578

Convolvnlaceae ( 556-562 ) Polemoniaoeae ( 56.H-567 ).

KorasiiiJiceae (56ít-57ít)

556. CuHCUtfi ¡¡laniffora 564.

557. Cuscuta, vpithymum 565.

558. Cuscuta eitilinum 56ti.

559. Cuscuta indecttra 567.

560. Cuscuta ffcntagoiia 568.

561. Cuscuta raccmusa .ar. 56Í*.

Chiliann 570.

562. Cuscuta (jronovii 571.

56.'-i. CoUomia gracilis 572.

Collo m ia firandipoi'u

(lilia capitata

N(i rarrctia in tertcxta

Nararictia squarrosa

PhnccUa sp.

Alhtrarya sp,

.4 msinckia in tcrmcdia

Amsinckia tcsselata

Aspcrugo ftrocumhcux

Hydrophyllaceae Í 568 ).

573. /-Jchium nuUforc

574. Hcliotrofiium curassnri575. l/cliotiopiunt europa cum

576. LapiHtla cchinata

577. Lappula ocridcntnlis

578. JJthospcrmum arvcnsc

57îi. Mifosotis arrCUSíS
Agriculture Handbook No. 30, U. S. Dcpt. of Agriculture PLATE XXVill

^

\^WP

¡580'" 581 583

589 •..•• W

a¿> 9^^ 593 ¡-4 594 ^^ 595

Boragiuaceae f580). Verbenat-eae (581-

580.

581.

582.

5S3.

584.

585.

586.

58T.

588.

PlagiohothrifH sp.

lApiiid nodiflorn

Verbena ho-<tata

Verbena officinalik

Verbena Ktricta

Verbena urticaefolia

Ajuf/a ehamae¡)ity*t

Bnilota nigra

(ialeo/ntix ladanum

58Ö. Gnleoiiifis tetrahit

59<i. Hedeoma /mlegioides

591. Lamium fimpJexkauJe

592. Leonurtts cardiaea

~)U'^. Lycopu^ rirginicuft

594. Marruhium rulgnre

595. Mentha arrensin

59f>. Mdhlavira ¡tarniftora

597. Nepeta cataría

[.abiatae I580-(JO:î)

598. I'nnieUa inilgaris

599. Pftenanthemnm sp.

(A'OPÍ/Kí sp. I

600. Salria lauceolata

*>01, Sal I) i a rerticHiatu

602. Satureja arinoft

603. Satureja nepeta
Asriculture Handbook No. 30. U. S. Dept. oí Agriculture PLATE XXIX

^^^^Pr - 606 ^ 607

x5 » y^~^Râ

616 etr* XI

» Í •

624* 625 627

Labiatap (604-011). Solanaceae 1612-622). Sor<i|iliiilaria(eae (623-627)

604. iiatiirejd nilynri-i

605. difteritis montana

61)6. .S'íac/))/» anima

607. í<tacit>/'< i/atti><tris

608. Teiicriiim h'itry»

609. Tciuriiim canndense

610. Tiichoxtema dicliotom li m

611. TrirlioKtema lanceolat ti m

612. Dafnia Htiumuniuin

61.'1. Hiiosa/amiix niger

614. PhyuatiM lobata

615. PlillHatix longifolia

616. Pliynalif nnbglabrata

617. Sotanuin carolinenxe

621. ÍSolaiuiin triflornin

622. "Stone cells"

62H. f:uphraKÍa sp,

624. Kickj-ia spuria

625. Linaria vutgarin

626. Melamiiyrum arvense

618. Solannin elneagnifotinin 627. scroiihularia maritan619. Solaniim nigruin dica

620. f'Otanuin rontratiim
Agriculture Handbook No. 30. U. S. Dcpt. of Agriculture PLATE XXX

632 633 634 635

636 ê !!9 ffm

640

x7 i/e xio

ê

649

Scrophularlaeeae (628-631). Pedaliaceae (632), Plantasinaoeae (63.S-644),

Rubiaceae (645-650), Caprifoliaceae (651)

628. Verbascum thapsus 637. Plantago pxyllium 645. liiodia teref<

629. Veronica agrestis 638. Plantago arenaria 646. Diodia rirginiana

6.30. Veronica arvennis 639. Plantago lanceolata 647. Galium aparine

631. Veronica peregrina «40. Plantago rhodospcrma 648. (Uilium mollugo

632. Se^amum orientale 641. Plantago pusilla {P. 649. fifiimtonia purpurea

6.Í3. Plantago major elongata) 650. Slieranliti arrensin * 634. Plantago ritgelii 642. Plantago hirtella 651. Symphoricarpos occi635. Plantago lirginica 643. Plantago coronopus dentalis

636. Plantago Uristata 644. Plantago orata
Agriculture Handbook No. 30, U. S. Dept. of Agriculture PLATE XXXI

^72 673

Valerianaceae (652-654), Uipsaoaceae (655-65S l, Campanulaeeae (659), Lobt'liaceae (660).

Compositae (661-675)

652. Valerianella locuffta var.

oiitoria

653. Valerianella dentata

654. Valerianella erioearpa

655. Cephalaria tratiHylvanica

656. Diitsavjis nylvetttris

657. Î^cahioêfl arrenxi»

658. i^eahinxn s|>.

659. Spéculât ia ¡terfoliata

660. Lobelia inpata

661. Aehillea millefolium

662. Avhifrachaena rnoUis

663. Amhroiiia artemisiifolia

664. .4mbroAÍff psilofttachya

665. .4mftro.sifif trífida

666. Anthemix arrensin

667. Anthémis rotula

668. Anthémis tinctoria

669. AplopappuH ciliatua

{Prionopsis viliata)

(i7(). ArífíHm lappa

671. Ar/íOííf/ís m.trt/ma

672. Brauneria angustifolin

673. CavduuH crlspus

674. f'«rrfi/H.v acanfhoidex

675. Carduus marrocephalun
Agriculture Handbook No. 30, U. S. Dcpt. oí Agriculture PLATE XXXll .

WM^^

67H. Cariliiiin ili/cnovcpjiallix

677. Curtliiimiix tinctoriiis

1)78. Centdiirea calcitraiHi

(i79. Centaurea c.i/nnw.s

(>8<l. Centaurea ibérica

081. Centaurea jarea

K82. Centauren maculoKa

683. Centaurea melitensix

684. Centaurea iiieris (C.

repenn)

Coiiiliositae (07G-699)

(iSô. Centaurea xeahioKa

686. Centaurea Kolxtitinli«

687. Centromadia. sj».

688. ChonflriJta júncea

(i8i). Chrilnanthemum leucanthcmum

(uto. Cicliorium intj/bun

6Í)1. Cimium arrcnie

(i'Ji. Cirnium ruli/are (C. iniíceoiatum )

6!):). rt. Creinx caiiillari«

b. Crepix aetoxtx

Erechtitex hieracifolia

Erechtite« iircnanthoides

Eriyeron annuiis

6!)7. Erifieron canadcnuis

()!)8. Frdnneria dincolor

609. Franieria tenu ifolia

(i!14

(i!)5

696.
Agriculture Handbook No. 30. U. S. Dcpt. ot Agriculture PLATE XXXIII

704 705

#«%

716 717

! I» H

TOO. GaUnaoga parviflora

70i. firlnAelia .iQiiarrona

702. HeUmithwi annuim

iiM. HeUanthim riliarix

T<14. Hemisonia iilziiltic/oHa

7o.^. Hetrrotheca graiuliflorn

7i>6. Hieiiiciiim iiurantinrum

"(17. Hi/iioclinerii yiuliintn

lüS. ita axUlarls

722

Composirae (T00-72SI

709. ¡rii ciliiitn

710. /i-fl xnnthifolia

711. Ldcttica fttntnleiish

712. Lnrtitea NiarinUi var.

iiiteijrifolia

7i:i. Lactuca puh-hella

714. La/jnaiiu commiiiiis

715. LmiitO'lon ttiitumnalit

716. I.coiitoilon »»rfic'iH/i*'

'"723

717. Madia glomerata

718. Madia sátira

719. J/nírieoria inodora

720. Picrifí echioides

721. Ficriíi hieracioideft

722. Katibida columiiaria

723. Rudbeckia hirta
AgricuUure Handbook No. 30. U. S. Dept. of Agriculture PLATE XXXIV

724. fleiiecio ;neo(>oeo

725. Henecin rulgariii

726. Sonchus arvensia

727. Sonchii» aupcr

728. iSoHi'/iH-s olcraceita

ComposiT.^e I724-7;I."'M

729 rnnacetiim rulgaic 7?.."!. Tragu/mgoii pratenxia

780. Tarnj-aciim offlcinule 7.14. Vrrnoiiia norehoracensia

7:!1. raittxucum eii/thro»iicr- 735. Xeraiithcmiim uyliniiramum citim

7.'!2. TiielcKiicnna sp.
DEVELOPMENT, STRUCTURE, AND HEREDITARY

CHARACTERISTICS OF SEEDS

Our important agricultural and vegetable crops belong to two families of monocotyledons and about 15 families of dicotyledons. The

monocotyledons include the grass family (Gramineae) to which belong the cereals, millets, corn, and various grasses, and the lily family

(Liliaceae) to which belong onion, chives, and asparagus. The dicotyledons include the remainder of our important agricultural and

vegetable crops, for example : The legume or pea family (Leguminosae) ; mustard or crucifer family (Cruciferae) ; cucurbit family

(Cucurbitaceae) ; nightshade family (Solanaceae), to which belong

tomato, potato, eggplant, and pepper ; and the sunflower or composite

family (Compositae). The flower, the seed, and the fruit produce new

individuals, perpetuate the species, multiply the number of plants of

the species, and disperse the species over a wide area.

Ovules and seeds of bluegrass and alfalfa are used to illustrate seed

development in monocotyledons and dicotyledons, respectively.

THE FLOWER

A typical flower consists of a receptacle, sepals, petals* stamens, and

pistil. In a complete flower, the sepals (collectively called the calyx)

form the outermost whorl of flower parts, the petals (collectively called

the corolla) the second whorl, the stamens the third whorl, and the

pistil or pistils occupy the center of the flower. The calyx and corolla

together form the floral envelope or perianth and are not essential in

leproduction. The stamens and pistil bear the essential reproductive structures. The stamen consists of two parts: The stalk or

filament and an anther containing one to four pollen sacs. The pistil

consists of three parts : The tip or stigma, on which the pollen grains

alight and germinate ; the middle or elongated portion, called a style ;

and the enlarged basal portion, or ovary.

The ovary is the part of the pistil that contains the otule or ovules

which develop into seeds. The surfaces or areas at which the ovules

are attached are known as the placenta. The attachmejit (placentation) may be to the walls of the ovary (parietal), to a stMklike structure extending up through the center of the ovary (axial and free central) , or a single ovule may be attached atthe base of the ovary (basal).

The young ovule consists of nucellus (a mass of cells which originate

as a protrusion of the placenta) surrounded by one or two layers of

tissue called integuments (pi. XXXV, Ä),

DEVELOPMENT OF THE OVULE

A specialized cell in the nucellus of the ovule becomes directly or

through division the megaspore mother cell. This cell has each

chromosome in duplicate (the diploid number or 2n). The spore

957116—52 18 i

263
264 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

mother cell undergoes two successive cell divisions (meiosis) forming

four megaspores, each with a single complement of chromosomes (n).

Itis during the first division of the spore mother cell into two daughter

cells that the chromosome number is reduced to the haploid number

(n), or a single complement. Only one of the four megaspores persists, the upper three gradually disappearing while the other enlarges

(pi. XXXV, A), This cell (megaspore) undergoes a series of three

divisions producing an eight-celled structure, called female gametophyte (pi. XXXV, ^).

Actually the eight nuclei are usually not separated by cell walls ;

nevertheless they are referred to as cells. Four of these three nuclei

or cells lie toward the chalazal end (position on the ovule where the

integuments blend with its other parts) and four toward the micropylar end of the embryo sac. One cell from each end moves toward the

center, the two being called the polar nuclei. They lie in close contact,

usually without fusing, until the time of fertilization. The three cells

toward the chala2;a are referred to as antipodal cells. In some species

there are six or more antipodal cells. The center of the three cells

toward the micropyle is the egg cell or megagamete and the two cells

near it are called synergids or helper cells. The latter two gradually

disappear. At this stage the Qgg cell is ready for fertilization by a

sperm nucleus.

DEVELOPMENT OF THE POLLEN GRAIN AND THE GENERATIVE CELLS

While the above-mentioned changes are taking place in the ovule a

similar reduction division is going on in the pollen sac. Here, specialized cells, called microspore mother cells, go through two successive

divisions resulting in four young pollen grains (microspores), each

with the reduced number (n) of chromosomes. Unlike the situation in

the megaspores where only one is functional, each of the four pollen

grains is capable of germinating and effecting fertilization. The

mature pollen grain or male gametophyte contains a tube nucleus and

a generative nucleus.

FERTILIZATION

Subsequent to pollination the mature pollen grain germinates producing a pollen tube which penetrates the style and makes its way into

the ovary and finally penetrates the embryo sac. During this time

the generative nucleus divides to form two sperm nuclei which move

through the pollen tube into the embryo sac. One sperm nucleus

unites with the egg nucleus (each with n chromosomes) to form the

one-celled embryo with 2n chromosomes. At about the same time

there is also a fusion of the other sperm nucleus with the two polar

nuclei, each with n chromosomes, to form the 3n endosperm nucleus

(pi. XXXV, (7, D), The fusion of one sperm nucleus with the egg

cell and the other sperm with the two polar nuclei is commonly known

as double fertilization.

TYPES OF OVULES

Such exterior markings of seeds as hilum, micropyle, chalaza or

strophiole, and raphe result from the type of ovule and are useful in
Agriculture Handbook No. 30, U. S. Dept. of Agriculture

PLATE XXXV

«m

PLATE XXXV

DEVELOPMENT OF THE EGG CELL IN BLUEGEASS

A.—Poa pratensis. Longitudinal section of an Immature ovary, showing the ovule

attached to the placenta of the ovary wall ; the ovule consists of a nucellus having four

linear megaspores surrounded by two integuments ; the Inner and outer Integuments each

consisting of two layers of cells. X 210

B.—Poa compressa. Longitudinal section of the eight-celled female gametophyte surrounded by the nucellus showing the egg cell or megagamete and two synerglds toward the

mlcropyle ; two polar nuclei at the center ; three antipodals toward the chalaza. X 500

O.—Poa compressa. Longitudinal section of the embryo sac showing a two-celled embryo

toward the mlcropyle ; two polar nuclei at the center ; three antipodals toward the chalaza.

X 500

D.—Poa compressa. Longitudinal section of the embryo sac showing a three-celled

embryo toward the mlcropyle ; endosperm nucleus at the center ; three antipodals toward

the chalaza. X 500

Abbreviations : a, antipodals : e, egg cell or megagamete ; em, embryo ; en. primary endosperm nucleus ; it, inner integument : oi, outer Integument ; ow, ovary wall or pericarp ;

pn, polar nuclei ; syn, synerglds.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 265

the identification of seeds. As the ovule develops into a seed it may

assume one of four positions in respect to its attachment to the placenta. Before describing these types of ovules, some of the technical

terms to be used will be defined. The terms "nucellus," "chalaza," and

''integuments" have already been introduced. The funiculus is the

stalk by which the ovule is attached to the placenta. The raphe is a

ridge along one side or edge of some seeds caused by nondivergence of

the funiculus with the integuments of an inverted ovule. The hilum

is a scar on the seed caused by breaking of the funiculus or seed stalk

when the seeds are shed or threshed. The micropyle is the pore

extending from the nucellus through the integuments.

An orthotropoKs or straight ovule extends in a straight line from

the funiculus, the micropyle and funiculus being on opposite ends of

the ovule and seed. Buckwheat and rhubarb seeds are examples of

this type of ovule. In the anatrofous or inverted ovule the nucellus

and integuments are inverted alongside the stalk or the funiculus, the

micropyle being directed toward the placenta. The integuments remain adnate to the funiculus, thus forming the raphe. Cotton and

okra are examples of this type of ovule. The hemitropous or halfinverted ovule differs from the anatropous type in that the funiculus

is adnate to the integuments for only about one-half the distance of

the ovule or seed, as in the common mallow. The campylotropous

or curved ovule is intermediate between the anatropous and orthotropous types. The nucellus grows more on one side than the other

forming a kidney-shaped ovule or seed in which the micropylar end

is brought down close to the funiculus, as in the clovers, alfalfa, bean,

and other legumes (pi. XXXVI, A),

DEVELOPMENT OF THE SEED IN MONOCOTYLEDONOUS PLANTS

In the Gramineae (grains and grasses) the so-called seed is a

caryopsis or fruit (disregarding the glumes, lemma, and palea).

However, the seed of the Liliaceae (onion and asparagus) is a true

seed.

EMBRYO

After fertilization the first division of the one-celled embryo of the

Gramineae is transverse resulting in a two-celled embryo. There is

rapid cell division resulting in a club-shaped embryo (fig. 64, A^ 5,

C^ D), A lateral notch is first differentiated, in the club-shaped

embryo, above which the scutellum or cotyledon develops. Later

protuberances or outgrowths are formed which become the coleoptile

(leaf sheath) almost completely surrounding the epicotyl (fig. 64,

A, F^ G^ H). The epicotyl soon becomes differentiated into a terminal

bud and leaves (fig. 65). Then the primary root and root cap, ensheathed by the coleorhiza (root sheath), are differentiated. The

outermost regular layer of cells of the scutellum bordering the endosperm is termed the epithelial layer (fig. 65). In the mature embryos of wheat, corn, and oats, two or more adventitious roots arise

just above the scutellar node. These are not present in the bluegrass

embryos.
266 AGRICULTURE HANDBOOK KO. 3 0, U. S. DEPT. OF AGRICULTURE

ENDOSPERM

The endosperm nucleus undergoes division at about the same time

as does the embryo. At first free nuclear division occurs which soon

becomes cellular; then cell division is active throughout, but later

it is localized to the outer or peripheral region. The outermost layer

of endosperm is called the aleurone layer.

FIGURE 64.

A.—Poa compressa. Longitudinal section of a young embryo composed of 3

cells. X 310

B.—Poa compressa. Longitudinal section of a young embryo composed of 9 or

more cells. X 310

C.—Poa pratensis. Longitudinal section of a young embryo composed of 14 or

more cells. X 310

D.—Poa pratensis. Longitudinal section of a young embryo showing indentation

which indicates outgrowths above and below it. X 310

E.—Poa compressa. Longitudinal section of a young embryo. The two outgrowths are rudiments of the coleoptile surrounding the vegetative cone,

plumule, or epicotyl. A smaller embryo lies over the lower half of the larger

embryo. X 310

F.—Poa compressa. Longitudinal section of a young embryo. The coleoptile

appears to surround completely the vegetative cone or epicotyl. The epiblast

is beginning to be differentiated. X 310

O., H.—Poa compressa. Two consecutive longitudinal sections of the same immature embryo. In one section (O), the coleoptile appears to surround completely the vegetative cone, plumule, or epicotyl. In the following section

(H), the coleoptile does not completely surround the epicotyl. A rudimentary

epiblast and scutellum are present. X 310

Abbreviations : ci, coleoptile ; em., embryo ; ep, epiblast ; sc, scutellum ; vc, vegetative cone, plumule, or epicotyl.
r

TJ

r

>

H

m

X

X

X

<

OVULES OF ALFALFA

A.—Medicago sativa. Longitudinal section oí an ovule and part of another ovule showing the ovary wall on both sides ;

iunieulus : micropyle ; chalaza ; nucellar cells ; egg cell ; or magagamete ; one of the two synergids ; inner and outer integuments

each consisting of two or more rows of cells. X BOO

B.—Medicago sativa. Longitudinal section of an ovule showing a young embryo with a narrow peripheral band of free

nuclear endosperm (torn in sectioning) ; hilum ; chalaza; inner and outer integuments. X 180

Abbreviations : ch, chalaza ; cw, carpel wall or ovary wall ; e, embryo ; en, endosperm ; /, funiculus ; h, hilum ; «, Inner integument ; m, micropyle; mg, megagamete or egg cell; nc, nucellar cells; oi, outer integument; ov, ovule; s, strophiole ; ayn,

synergids.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 267

FIGURE 65

Poa pratensis. A composite drawing of successive longitudinal sections of a

mature embryo, showing scutellum with a rather poorly defined epithelial

layer and with a procambium vascular strand; vegetative cone or epicotyl

with the terminal bud and two or three leaves differentiated; coleoptile or

sheath surrounding the plumule or epicotyl; primary root terminated by a

root cap ; the coleorhiza surrounding the root and root cap ; epiblast. X 280

Abbreviations: cl, coleoptile; GO, coleorhiza; ep, epiblast; jl, foliage leaves;

r, radicle or primary root ; re, root cap ; sc, scutellum ; vc, vegetative cone,

plumule or epicotyl; vs, vascular strands.
268 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INTEGUMENTS (SEED COATS) AND OVARY WALL (PERICARP)

The seed coat consists of an ovary wall adnate to the two integuments. In the young fruit (fig. 66, Ä, B) the ovary wall consists of

an outer row of epidermal cells, four or five rows of starch-containing

parenchyma cells and an inner row of chlorophyll-containing cells.

The green color of developing and fresh mature seed is attributed to

the chlorophyll layer. Each of the two integuments consists of two

A.—Poa pratensis. A portion of a longitudinal section of a very young ovule,

showing nucellus ; inner integument composed of two rows of cells and its

inner wall slightly siiberized ; outer integument composed of two rows of cells ;

ovary wall of about five rows of cells, of which the inner layer is the chlorophyll layer. X 310

J1.—Poa pratensis. A portion of a longitudinal section of a young ovule, showing

nucellus ; two integuments, of which the inner layer of the inner and of the

outer integuments are slightly suberized ; and a part of the cells of the ovary

wall. X 310

C.—Poa compressa. Photomicrograph of a portion of a longitudinal section of

an immature ovule, showing aleurone cells with thin walls ; one or two rows of

nucellar cells ; inner walls of inner integument suberized ; a layer of suberin

as the only remnant of the outer integument ; ovary wall. X 310

D.—Poa compressa. A portion of a longitudinal section of a slightly older ovule

than G, showing aleurone cells with thin walls ; inner walls of inner integument suberized ; a layer of suberin as the only remnant of the outer integument ; ovary wall with the epidermis slightly cutinized. X 310

E.—Poa compressa. A portion of a longitudinal section of an ovule almost mature, showing aleurone cells with thick cell walls ; inner integument with its

inner walls suberized, cells less turgid, somewhat shrunken and collapsed,

containing some starch ; ovary wall cells beginning to collapse. X 310

F.—Poa compressa. A portion of a longitudinal section of a mature ovule, showing aleurone cells with thick walls; cells of inner integument compressed,

and inner layer suberized ; outer integument only a thick layer of suberin ;

ovary wall cells crushed and compressed into a thin layer. X 310

Drawings made from sections of fresh material.

Abbreviations: al, aleurone cells; chl, chlorophyll layer; c, cutin; ec, epidermal

cells ; ii, inner integument ; nu, nucellus ; oi, outer integument ; oto, ovary wall ;

s, suberin.
Agriculture Handbook No. 30, U. S. Dspt. of Agriculture PLATE XXXVI 1

OVULES OF ALFALFA

A.—Medioago sativa. Longitudinal section of an ovule showing a well-developed embryo

with root (plerome, perlblem, root cap, and suspensor) ; epicotyl ; cotyledons ; endosperm ;

inner and outer integuments ; hilum ; strophiole. X 80

B.—Medioago sativa. Longitudinal section of a mature ovule or seed showing the embryo

with portions of the two cotyledons ; epicotyl with the terminal bud and one or two leaves

differentiated ; root differentiated into plerome, perlblem, root cap and suspensor ; hilum.

X 60.

Abbreviations : cot, cotyledons ; ep, epicotyl ; en, endosperm ; h, hilum ; m, micropyle ;

per, perlblem ; pi, plerome ; r, root ; re, root cap ; s, strophiole ; sus, suspensor.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 269

rows of cells except toward the micropyle and chalaza where there are

more layers. All the cell walls of the inner and outer integuments

contain pectin and some also contain suberin.

When the caryopsis of bluegrass is fully grown and mature, the

seed coats are greatly modified in regard to both structure and composition. The cells of the ovary wall are tightly compressed and

disorganized. The outer walls of the epidermal layer of the ovary

wall are slightly cutinized and a thick layer of suberin is formed on

the inner row of cells of the outer integument. The cells of the inner

integument are mainly compressed leaving a narrow band of suberin

formed from their walls. The cell identity of the inner integument

can be seen where the seed coat is torn (fig. 66, ¿7, Z>, £*, F).

The seeds of most grasses and some of the grains (oats and barley),

are enclosed in one or two pairs of glumes which persist after threshing. The cell walls of the glumes usually contain such substances as

lignin, suberin, and cutin in addition to pectin and cellulose which are

the usual constituents of cell walls. Suberin and cutin are waxy and

water repellent, therefore prevent water from entering the seeds.

DEVELOPMENT OF THE SEED IN DICOTYLEDONOUS PLANTS

The seed of commerce of most of our economic, dicotyledonous plants

is either a true seed or a dry indéhiscent fruit. The seed of alfalfa

has been selected to represent the seed of a dicotyledonous plant.

EMBRYO

The one-celled embryo of alfalfa {Medicago sativa) divides transversely, thus forming a two-celled proembryo ; a linear row of six cells

is developed by further division. The embryo is developed from the

apical cell of the six-celled proembryo whereas the remaining cells

produce the suspensor. The cotyledons, epicotyl, root, and root cap

are differentiated early (pi. XXXVI, A, 5; XXXVII, A), In the

mature seed the embryo, consisting of two fleshy cotyledons, a small

differentiated epicotyl, and a well-developed root, practically fill the

entire seed (pi. XXXVII, B).

ENDOSPERM

The endosperm cells develop in a free parietal layer similar to that

described for bluegrass but are apparently used as food by the growing embryo prior to maturity as the mature seed contains only one

or two rows of endosperm cells (pi. XXXVI, B ; pi. XXXVII, A,B).

The mature embryo consisting of a small epicotyl, two large cotyledons,

a well differentiated root, and two or three rows of endosperm within

the seed coat constitutes the mature seed in alfalfa and many other

dicots. However, in some dicotyledonous plants (Amaranthaceae,

Chenopodiaceae, Polygonaceae, and others) the endosperm develops

and is present in the mature seed similar to that described for the

monocotyledonous plants.

INTEGUMENTS OR SEED COATS

The seed coat consists of two integuments. The inner integument

consists of two or more rows of cells and the outer integument of three

or more rows (pi. XXXVI, ^; pi. XXXVIII, A). The outermost

cells of the outer integument in legume seeds are termed Malpigliian
270 AGRICULTURE HANDBOOK NO. 30; U. S. DEPT. OF AGRICULTURE

cells. The cells beneath them are the osteosclerid or hourglass cells.

When the ovule is immature, as shown in plate XXXVI, A, all the cell

walls contain pectin. In addition, a thin layer of cutin is present on

the outer tangential walls of the Malpighian cells as well as a layer of

suberin on the tangential walls of the innermost cells of the inner

integument.

When the ovule is immature and green and the embryo is differentiated (pi. XXXVI, B ; pi. XXXVII, A ; pi. XXXVIII, B, G)

but not fully grown, the upper parts of the radial walls and the outer

tangential walls of the Malpighian cells have thickened. These thickenings appear as V-shaped plugs extending in between the cells. In

the mature seeds these radial walls are not visible and appear as a continuous layer, variously referred to as the cuticularized layer and the

subcuticular layer. The upper radial and outer tangential walls of the

osteosclerid cells have also thickened leaving a space between the upper

portions of the cells. All the cell walls of the inner and outer integuments, including the V-shaped plugs of the Malpighian cells and the

thickened walls of the osteosclerid cells, contain pectin and certain

walls contain cellulose. In addition, a thin layer of cutin is present on

the outer tangential walls of the Malpighian cells and a layer of

suberin is present on the tangential walls of the cells of the inner

integument adjacent to the nucellus.

When the seed is mature and the embryo occupies practically all

the space within the integuments (pi. XXXVII, B\ pi. XXXIX, A^

B) the Malpighian cell walls are greatly thickened. AH the cell walls

of the inner and outer integuments contain pectin and certain walls

contain cellulose. A slightly thicker layer of cutin is present on the

outer tangential walls of the Malpighian cells in the mature seed

than in the w^alls of immature seed. A layer of suberin is present

on the tangential walls of the cells of the inner integument adjacent

to the nucellus. Suberin is also present in the so-called cones and

light line. The aleurone cells in the mature seed have very thick

walls which are considered mucilaginous.

The greatly thickened, cutinized, and suberized walls of the seed

coats of the Leguminosae are presumably the reason for the large

number of hard seeds found at the termination of the germination

tests of some species of this group.

Treating mature seeds of alfalfa with a 1-percent solution of osmic

acid reveals a blackened area on the other side of the hilum from

which the micropyle is located. It is the portion -of the seed coat

covering the chalaza and is considered by some investigators to be

the area where water enters, thus resulting in a permeable seed. The

Malpighian cells directly covering the chalazal region is referred

to by some research investigators as the strophiole and by others engaged in seed identification as the chalaza. There is a cleft in the

center of this area. A section through it reveals the Malpighian cells

directly beneath as very straight and the cells appear as though they

might split apart quite readily when the seeds receive a sharp blow,

thus resulting in a permeable seed. Whether water enters at this

area (strophiole or chalaza) and not at the hilum or micropyle has

not been definitely established (pi. XXXVII, A-, pi. XXXIX, G),

However, the hilum contains much suberin in alfalfa seed.
SEED COAT OF ALÍ-ALFA

A.—Medicago sativa. Portion of the seed coat enlarged from plate XXXVI, B. The outer integument consists of the three outermost rows of cells : Malpighian or palisade cells, osteosclerid cells and one row of parenchyma tous cells. The inner integument consists of the three innermost rows of

parenchymatous cells. X 1,200.

B.—Medicago sativa. Drawing oí a longitudinal section of a young ovule of about the same age as plate XXXVII, A. The upper radial walls and

the outer tangential walls of the Malpighian cells have thickened and appear as V-shaped plugs ; the upper radial and outer tangential walls of the osteosclerid cells have thickened ; and two rows of parenchymatous cells constitute the outer integument. The two rows of longer cells constitute the inner

Integument. Aleurone and one or two rows of endosparm cells are also visible.

C.—Medicago sativa. Enlarged portion of the seed coat of the longitudinal section of plate XXXVII, A showing the same points as stated under

B. X 600

Abbreviations : al. aleurone cells ; chl, chloroplasts ; en, endosperm cells ; ii, inner integument ; o, osteosclerid cells ; oi, outer integument ; Mai, Malpighian cells ; n, nucleus.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 271

THE SEED

The seed may be defined as a mature ovule as distinguished from

a fruit which is a mature ovary. The seed consists of an embryo with

reserve food, as endosperm and nucellar tissue surrounded by one

or two integuments or seed coats. However, either or both the endosperm and nucellar tissue may be lacking in which case the reserve

food is contained in the cotyledons of the embryo.

The term seed has two different meanings. The botanical definition

is based on structure, the seed being a product of the ovule without

any additional structures. The other definition (nonbotanical) of

seed is based upon the unit commonly used for planting purposes,

regardless of structure. It includes the following three types of

structures: (1) True seeds as indicated above, such as alfalfa and

cucumber; (2) true seeds enclosed by the dry, indéhiscent ovary walls

(fruits), as the caryopsis in grasses and the achene in lettuce; and

(3) true seeds enclosed by ovary walls, surrounded by additional

structures or embedded in a mass of tissue as in New Zealand spinach

and beet. The first of these three types needs no further mention as

the development of the true seed (alfalfa) has been treated in detail.

The second type of "seeds," botanically referred to as single-seeded

dry indéhiscent fruits, includes four types as follows :

1. The seed of the entire grass family is a caryopsis. In the caryopsis the seed coat is joined to the ovary wall so firmly that they cannot be separated.

2. The achene of the buckwheat, sedge, and composite families and

certain genera in other families differs from the caryopsis only in

that the pericarp is attached to the seed at the base. Thus, the seed,

including seed coat, can be separated from the ovary wall.

3. The fruit in parsnip, parsley, carrot, and celery and other

members of the Umbelliferae is a schizocarp. The ovary of the schizocarp contains two seeds. During development of the ovary a longitudinal constriction forms between the two seeds forming two mericarps or half fruits. At maturity the mericarps split apart and are

then like the achene in structure.

4. The ovary in the Boraginaceae, Verbenaceae, and Labiatae

(borage, vervain, and mint families) divides longitudinally, during

development, into four small nutlets, each containing a single seed.

There are a few "seeds" encountered in seed testing which consist

of structures additional to single-seeded fruits. In beet there is a

fusion of ñower parts which enclose one to several seeds. The New

Zealand spinach seed is a hard nutlet usually containing several

individual seeds, surrounded by a fleshy calyx with hornlike protuberances. There are also other accessory structures which form a part

of certain so-called seeds as in cocklebur, ragweed, povertyweed, sandbur, and buffalo grass.

HEREDITARY QUALITIES OF THE SEED

Through reproduction there is a transmission of life from one

generation to the next. Certain traits or characteristics are passed

from the parents to the offspring. It has previously been stated that

the nucleus (germ plasm) of the 1-celled embryo contains 2 sets of

chromosomes, 1 set with the haploid number contributed from the

957116—52 19
272 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

Qgg nucleus (7 chromosomes in peas) and 1 set, also with the haploid

number, contributed by the sperm nucleus (7 chromosomes in peas).

The similar chromosomes from each nucleus of the gametes pair in

the nucleus of the zygote (a total of 14 chromosomes in peas). The

chromosomes are carriers of genes or factors which determine hereditary characters or traits. Each pair of similar or homologous

chromosomes has 2 genes which will determine a character or trait.

Mendel showed through his experiments that mating a tall pea plant

with a dwarf pea plant resulted in all the plants of the first filial

generation (Fi) being tall plants. All the Fj plants have a gene for

tallness and a gene for dwarfness. He called the parental trait which

was expressed "the dominant trait" and the parental trait which was

not expressed "the recessive trait." The Fi plants are all tall. The

phenotype or appearance is tall but their genotypic constitution is

not pure for tallness because the Fi plants possess both the dominant

tall gene and the recessive dwarf gene.

Mendel showed that the Fi hybrids were not genetically pure

through self-pollination and subsequently self-fertilization. The

seeds from the Fi generation produced both tall and dwarf plants

in the second filial generation (Fg). They were in the proportion of

3 dominant tall plants to 1 dwarf recessive plant. The F2 plants

were also self-pollinated. Seeds produced from the F2 plants were

grown to obtain the third filial generation of plants (Fg). All the

seed from the dwarf F2 plants produced pure recessive dwarf plants

(two genes for dwarfness). The seed from the tall F2 plants produced

one-third pure tall plants (two genes for tallness) and two-thirds

plants which were not pure for either the tall or dwarf trait (one

gene for tallness and one gene for dwarfness). The seeds from the

latter group of plants when self-pollinated produced plants in the

ratio of 3 tall plants to 1 dwarf plant which was like the Fi

hybrids that produced a ratio of 3 tall plants to 1 dwarf. Since

Mendel's time, other investigators have shown that genes do not always show complete dominance or recessiveness as reported in peas.

The genes may be only partially or incompletely dominant and the

effect of one gene may be greatly modified by another.

Such genetic principles as cross-fertilization have been used extensively by growers in the production of hybrid corn as well as by

many other breeders and producers of seeds, plants, and animals.

The most effective method of disease control is through breeding for

resistant varieties.
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SEED COAT OF ALFALFA

A.—Medicago sativa. Drawing of a portion oí the seed coat from longitudinal section of a mature seed as shown in plate XXXVII, B. The outer

integument consists of the Malpighian cells with thickened upper radial and outer tangential walls, cones, light line, cuticle and cell contents ; the osteosclerid cells with thickened upper radial and tangential cell walls ; and one row of parenchymatous cel:s. The inner integument consists of two rows of

cells which are crushed into a broad band.

B.—Medicago sativa. Portion of the seed coat from a mature living seed sectioned longitudinally showing the parts as stated under A.

0.—Medicago sativa. Section through the strophiole showing the straight Malpighian cells in the center surrounded by slightly curved cells on

either side. X 250

Abbreviations : al, aleurone cells ; c, cutin ; CO, cones ; en, endosperm cells ; H, inner integument ; II, light line ; Mai, Malpighian cells ; «, nucleus ;

o, osteosclerid cells ; of, outer integument.

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PHYSIOLOGY OF SEEDS ^^

THE RESTING SEED

The resting seed of most of the economic plants contains a welldeveloped embryo and reserve foods stored in the endosperm or in the

cotyledons of the embryo, all of which are enclosed in a more or less

modified seed coat. The food reserves present in cereals and legumes

are of great economic importance as they provide a large part of the

food supply of the world for both humans and animals. Respiration

is very low in dry resting seeds and the vital activities of the seeds

have almost stopped. The seed coats are very much modified and

in some kinds of seed contain impervious substances such as suberin

and cutin. These substances prevent the absorption of moisture by

the seed and the exchange of gases through the seed coat.

In the resting condition the seed is reasonably resistant to outside

environmental conditions as long as it remains dry. This is of

great economic importance, as seeds which have been harvested when

ripe and kept under favorable storage conditions will retain their

viability for a relatively long period and usually can be used for

planting from one to several years after harvesting.

THE PROCESS OF GERMINATION

Dry seed in the resting condition requires considerable moisture

before germination will take place. Under suitable moisture, temperature, and oxygen supply, the seed coat becomes softened and

more permeable to water and gases such as oxygen and carbon dioxide.

As water enters the embryo and endosperm the processes of digestion,

respiration, and growth are begun.

DIGESTION

The food in the resting seed is in a suitable condition for storage

but must be broken down through digestion before it can be used in

the germination process. Digestion is the process of chemically

breaking down a complex food into a simpler one. It is usually a

process of hydrolysis by enzymes wherein water is chemically added to

the compound and then broken down into a simpler form.

The starches are digested to sugars by the diastase enzyme system.

The sugars are soluble and can diffuse from cell to cell and be assimilated or used in respiration. The fats are digested to fatty acids by

the lipase enzymes, and the proteins to amino acids by the proteases

before they can be moved to the growing points and used by the

actively dividing cells. Assimilation is the process whereby the digested food becomes a part of the living protoplasm.

^* This section is Umited to basic background information with problems and

examples taken from crop seed, whenever possible. This subject is discussed in

greater detail in a book on seed physiolo,gy ( Physiology of Seeds by W. 0. Crocker

and Lela Barton) now in press.

273
274 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

RESPIRATION

Eespiration takes place in. all living cells regardless of their state

of activity or the environmental conditions which may surround them.

It is the means by which organisms obtain their energy for growth

and other life processes. Much of the energy produced during respiration is dissipated into the atmosphere in the form of heat. The

rate of respiration in air-dry seeds is very low but does occur, and

in some cases is measurable. In the case of old viable seeds which

have been stored at low temperatures and under low moisture conditions, respiration may practically cease. During germination the

respiration rate is high. The living protoplasm is continually active

and therefore requires energy.

Most respiration in plants and animals requires the presence of free

oxygen. It is a process wherein there is a chemical reduction of oxygen or some other substance by living cells, forming organic compounds and releasing energy, both of which are used in various life

processes. If free or molecular oxygen is used by the living cells,

the process is referred to as aerobic respiration. For example, the

chemical combination of glucose sugar and oxygen yields carbon

dioxide, water, and energy.

In protoplasm, the respiratory process is much more intricate than

may be inferred from this statement. Itinvolves successive reactions,

each controlled by an enzyme or enzyme system. The materials from

which energy is liberated are mainly the carbohydrates. The proteins are used mainly in constructive metabolism. If used in respiration, they must also be converted to carbohydrates. The fats must

be converted to fatty acids and finally to carbohydrates before they

are used in respiration.

Anaerobic respiration is generally considered to take place in the

absence of free or molecular oxygen. It involves the partial breaking down of chemical compounds with release of energy. Anaerobic

respiration commonly takes place in certain lower plants and sometimes in higher ones which are temporarily deprived of oxygen. The

alcoholic fermentation of glucose, in the presence of the enzyme,

zymase, yields carbon dioxide, ethyl alcohol, and energy without the

addition of molecular oxygen.

EMERGENCE OF THE SEEDLING

Subsequent to the processes of metabolism the radicle emerges

usually through the micropyle of the seed coat. Some seeds possess

structures and secrete substances which aid in removing the seed coat

during germination. These include the mucilaginous coats in flax

and mustard seeds, the peg in the cucurbits, and the arched hypocotyl

in cotton which lifts the convoluted cotyledons out of the seed coat.

During germination the cotyledons of some kinds of seeds remain

in or on the ground, the epicotyl elongates and pushes through the

soil. This type of seedling development is termed hypogeal and is

found in the germination of such seeds as the grasses, cereals, peas,

broad bean, runner bean, and vetches. In the germination of certain

other kinds of seeds the hypocotyl elongates pushing the epicotyl

and cotyledons above the ground. This type of germination is known

as epigeal and occurs in beans, clovers, cucurbits, and spinach. In

the germination of onion seed the cotyledon, which is the first con-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 275

spicuous aerial part, elongates and elevates the epicotyl above ground.

The epicotyl emerges through a pore or slit in the single cotyledon.

Cotyledons may serve primarily as the first leaves as in cotton,

radish, and lettuce, or they may be primarily storage organs for food

as in beans, peas, or peanuts, in the case of cucurbits, the cotyledons

serve both as storage and photosynthetic organs.

ENVIRONMENTAL CONDITIONS AFFECTING GERMINATION

An adequate supply of oxygen and moisture and a favorable temperature are necessary for the germination of all seeds ; in addition,

some kinds of seeds require light. The germination of some seeds,

particularly the grasses, is frequently more rapid and complete when

(1) the germination substratum is moistened with a nitrate solution,

(2) the glumes, palea, and lemma are removed, or (3) the test is made

m light even though the species is usually not light-obligate. In

studies of dormancy it is not possible to determine the stage at which

after-ripening ceases and germination begins. Thus, although the

factors influencing germination are discussed in systematic sequence

in the pages that follow, they are also frequently referred to in the

discussion of dormancy.

MOISTURE

An adequate supply of water is one of the essential requirements

m the germination of seeds before growth can proceed. Water enters

the seed by imbibition and is accompanied by swelling and possible

rupture of the seed coat. Water is necessary for both the physical and

chemical processes that occur in the germinating seeds. During

imbibition the dry seed coats become softened and more permeable to

water and gases. As the concentrated protoplasm becomes diluted the

enzymes are activated. Water is also necessary in digesting the insoluble complex foods to soluble forms and in transporting them to

the cells of the growing points of the embryo where they become assimilated into living protoplasm resulting in new growth of the

tissues or are used in respiration.

TEMPERATURE

Temperature affects the rate of chemical reactions, the absorption

of water, and the intake of oxygen by the seeds. In seed germination

work, optimum temperatures are those at which the largest number

of seeds of the particular species will grow ; maximum and minimum

temperatures are those above or below which the seeds will not germinate. The temperatures designated for the germination of seeds, in

the rules for seed testing, are regarded as optimum temperatures.

Many kinds of seeds germinate well at constant temperatures. The

small grains, vetches, clovers, radish, onion, and others germinate

very well at 20° C, unless they are freshly harvested or dormant

as is often the case with the small grains. Still lower constant temperatures such as 10° or 15° C. are favorable for the germination of

spinach seed and possibly other kinds. High constant temperatures

of 30° are favorable to a few kinds of seeds such as cucumber and

watermelon, especially if the seed is freshly harvested.

Daily alternating temperatures are necessary to obtain a complete

germination of many kinds of grass seeds. Alternations of 20° for 16
276 AGRICULTURE HANDBOOK NO. 30, U. S. BEPT. OF AGRICULTURE

to 18 hours and 30° for 6 to 8 hours are also found to be favorable for

the germination of seeds of many economic plants which, in nature,

require warm temperatures for their growth. Examples of such seed

include corn, sorghum, rice, Brassica species, and the cucurbits.

OXYGEN

The principal necessity of oxygen is in respiration which supplies

energy to maintain life by the oxidation of foods. It has previously

been stated that in its moist quiescent condition, the seed carries on

respiration. When the embryo resumes growth, as in the germinating

seed, respiration is greatly accelerated and oxygen is required for

this increased respiration. Seed coats are more permeable to gases

when moist than when dry but a film of water around the seed will

retard oxygen intake to the extent that seeds fail to germinate. Hence,

it is necessary to keep crop seeds moist but not wet in the germination

test.

Seed of Canada bluegrass was found to give significantly higher

germination results when tested in Petri dishes with the lids ajar

for a part of the time each day than when the lids were left on the

dishes continuously. The tests were conducted in a uniform temperature chamber, thus there should have been no great difference in

temperature between the open and covered containers (Andersen,

(4)). In laboratory practice the removal of Petri-dish lids at the

time of the preliminary counts and when rewatering apparently

affords sufficient aeration.

Germination is improved in some kinds of seeds, especially when

dormant, by alternately moistening and drying them for about 10

days prior to germination. Griswold {2Ji) has found this to be true

for 4 kinds of range grasses, and Andersen {3) for Canada bluegrass.

The alternate moistening and drying of the seeds may make the seed

coats more permeable to oxygen and carbon dioxide as well as to

water, especially since the seed coats are considered to be of a colloidal

nature.

LIGHT

Quick-germinating seeds such as pea, bean, clover, and radish are

indifferent to light, germinating equally well in the presence of light

or darkness. On the other hand, the germination of some kinds of

seeds is inhibited by light whereas most of the grass seeds require

light to obtain a complete germination. Seeds that show increased

germination when exposed to light are usually referred to as lightsensitive.

Our present knowledge of the effect of light on the germination of

seeds is the result of a gradual development in research during the

last 70 to 75 years. In 1881 Stebler {43) reported that light was

effective in the*^germination of seed of Poa, A few years later Cieslar

{11) reported that yellow light was effective in furthering the germination of grass seed whereas violet light retarded it. Kmzel {SO)

studied the effect of the different regions of the spectrum on many

seeds and concluded that the long visible rays promoted germination

more than the short rays. Kommerell {82) reported that light rays

in the region of 5100 AU (Angstrom units) were favorable for the

germination of tobacco seed and loosestrife seed.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 277

Flint (^^) reported results of detailed investigations relating to

the effect of light on the germination of lettuce seed in which the

effects of specific wavelengths were studied. The longer wavelengths

in the red, orange, and yellow regions of the spectrum, promoted

germination whereas the shorter wavelengths in the green, blue, and

violet regions inhibited germination. Maximum promotion of growth

occurred in the orange and short red color bands and maximum inhibition of growth in the purple and blue bands. The infra-red region

w^as even more inhibitive than were the green, blue, and violet regions.

NITRATE SOLUTIONS

Gassner (£S) reported that Knop's nutrient solution would replace light in the germination of seeds of Pampas grass (Ghloris

ciliata). He concluded that the stimulating action was the result

of the calcium nitrate in the nutrient solution and not to the nitrogen

free salts such as chlorides, phosphates, and sulphates. Some investigators have made comparative tests using soil moistened with water

and artificial substrata moistened with nitrogen compounds. On the

basis of these investigations it is generally concluded that the soluble

nitrogen compounds in the soil are responsible for the stimulating

action of soil in germinating light-sensitive seeds. It has been reported that solutions of potassium nitrate were more effective than

sodium or calcium nitrate in furthering the germination of Poa spp.

whereas lead nitrate proved to be a depressant. Many nitrogen

compounds (nitrates, nitrites, nitric acid, ammonium salts, urea, and

thiourea) have been found to stimulate the germination of lightsensitive seeds.

Much research has been conducted to determine the optimum concentration of nitrate solutions used in moistening the substratum on

which light-sensitive seeds are germinated. Tests with different concentrations of potassium nitrate have shown that the solution should

be kept as dilute as possible and yet remain stimulating to the dormant

seeds. Nitrate solutions may produce root injury to the seedlings,

especially 1- or 2-year-old seeds or well-ripened seeds. Very short

roots with few or no root hairs and inhibition of roots are symptoms

of nitrate injury. Although a 0.2-percent potassium nitrate solution

has been found optimum for most kinds of grasses, a 0.1-percent

solution is recommended for Kentucky bluegrass seed to avoid injury

to the roots. A combination of light, potassium nitrate, and alternating temperatures are necessary for complete germination of Agrostis, Lolimn^ Paspaluon^ and Poa seeds.

GLUMES (LEMMA AND PALEA) IN GRASSES

Removal of the glumes from such light-sensitive seeds as Pampas

grass {CMoris ciliata) and Poa spp. has been beneficial in their germination. The seed coats or glumes increase the necessity for light.

The glumes make Ghloris light-obligate and increase the need for

light in Poa spp. Caryopses of Canada bluegrass from which the

glumes had been removed and moistened with water, gave equal results to those with glumes intact and moistened with a 0.2-percent

potassium nitrate solution. Somewhat lower results were obtained

when caryopses without glumes were tested in darkness.
278 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

In some instances germination is greatly accelerated if the glumes

are removed. This is particularly true in the case of rescue grass

{Bromus catharticus) and Johnson grass {Sorghum halepense).

However, this is not regarded as sufficient reason to interfere with the

normal seed structure when testing for germination. Removal of

the glumes in grasses is not generally a part of the seed-testing procedure for the following reasons : ( 1 ) The glumes are difficult to remove ;

(2) dilute potassium nitrate solutions employed as the moistening

agent, or soil tests, will supplant the removal of glumes in most instances; and (3) most seed analysts and seed control officials object to

interfering with the structure of the seed unless there is no other

known practical method of testing for germination. * One exception, however, has been made to this practice in the rules

for seed testing. The glumes (lemma and palea) of Pasyalunfh notatwfïh are cutinized and fit together so tightly that a sharp scalpel is

required to splitthem apart. Itis presumed that water cannot readily

reach the caryopsis. By removing the glumes, a high percentage of

the viable seeds will germinate within approximately 10 to 14 days.

When the glumes are left intact it usually requires several months for

the seeds to germinate.

PHYSIOLOGY OF DORMANCY

Viable seeds of certain economic plants do not always germinate

when exposed to conditions considered optimum for the particular kind

being tested. They have a persistent rest period and are classified as

dormant seeds. Dormant crop seeds may be attributed to the following causes: (1) Impermeable seed coats ; (2) physiologically unripe or

freshly harvested seeds; (3) dormant embryos; (4) immature embryos; and (5) inhibiting substances.

IMPERMEABLE SEED COATS

Seeds that do not absorb water, when placed in wet or moist surroundings, because of an impermeable seed coat are referred to as hard

seeds. Practically all the hard seed encountered in testing crop seeds

fall in one of the following plant families : Leguminosae, Malvaceae,

Convolvulaceae, and Liliaceae. The seed coat in several genera of

legumes has been studied intensively to determine the structure concerned with the intake of water and the cause of hardseededness. The

impermeability of the seed coat of alfalfa, red clover, and sweetclover

is believed to be due mainly to the presence of cutin and suberin in the

walls of certain cells of the seed coat. Hardseededness, especially in

the small-seeded legumes, is a real problem in agricultural practices.

To overcome this problem seed lots of sweetclover, lespedeza, certain

clovers, trefoil, and black medic are frequently passed through mechanical devices designed to scarify or chip small portions from the

seed coats. These processes usually render the seed coats permeable to water, but often damage the seeds in varying percentages by

breakage.

Large numbers of swollen seeds are present in some samples of subterranean clover and suckling clover when germinated at 20° C. They

imbibe water but do not break the seed coat. At lower temperatures

(approximately 10° for sub clover and 15° for suckling clover) few

swollen seeds are present, which fact suggests that this type of dor-
TESTING AGRICULTURAL AND VEGETABLE SEEDS 279

mancy is due to the effect of temperature on the seed coat. Freshly

harvested seed of Alyce clover {Alysicarpus vaginalis) requires a germination temperature of 35° C. whereas 1-year-old seed will germinate

well at 30°. If the freshly harvested, swollen seeds are pierced, germination takes place immediately—a fact which also suggests that the

seed coat, and not the embryo, is the cause of dormancy.

It is believed by some investigators that imbibed seeds stay dormant

because oxygen does not pass through the coats sufficiently fast to permit germination of the embryos even when they have good aeration on

the outside. In fact, Brown {9) found that saturated seed coats of

Gyjcurbitapepo permitted carbon dioxide to diffuse through many times

as fast as oxygen. The bur of cocklebur {Xanthium species) contains

two seeds, commonly referred to as the lower and upper seeds. In

nature the lower seed germinates the first year and the upper seed the

second year. A similar behavior is observed in ordinary laboratory

tests. However, upper seeds germinate in a normal manner if the seed

coat is pricked or if the oxygen concentration surrounding them during

the germination test is increased to 76 cm. or a full atmosphere of

pressure. Thus, the seed coat of the lower seed is sufficiently permeable to oxygen to permit germination at ordinary conditions

whereas the seed coat of the upper seed is relatively impermeable to

oxygen at ordinary pressures and will not germinate unless its permeability is altered or the oxygen pressure is increased.

A complete atmosphere of carbon dioxide for a few days prior

to germination will overcome dormancy in Canada bluegrass seed.

On the other hand a complete atmosphere of oxygen does not overcome

dormancy in this seed (Andersen {2)), Thornton {J¡S) found that

high concentrations of carbon dioxide will induce germination of lettuce seed at high temperatures—seed that was formerly reported to

require light and low temperatures for germination. It is generally

agreed that in these cases the carbon dioxide either renders the tissues

more permeable or brings about changes which result in removing a

respiration block. In some cases high concentrations of carbon

dioxide appear to give stimulating effects similar to those given by

solutions of potassium nitrate. ^ It appears quite possible that both

agents cause the same changes within the seed.

PHYSIOLOGICALLY UNRIPE SEED

Freshly harvested seeds of cereals and grasses are frequently

dormant due to the fact that they are not completely ripened or that

they have been stored under conditions unfavorable to after-ripening

and still respond as freshly harvested seed when placed to germinate.

The seeds are thought to be morphologically mature but not physiologically after-ripened. Low temperatures are generally considered

to overcome this type of dormancy. Ripe seeds of wheat, barley, rye,

and oats germinate well at 20° C. whereas freshly harvested seeds

germinate well if placed at 10° in a moist substratum for 5 days

prior to being placed at 20°. If tested at 15°, they frequently do not

require the prechill treatment. Freshly harvested seeds of cereals

usually germinate more rapidly, more uniformly, and more completely

when prechilled, whereas old seeds usually respond better without

prechilling.

A combination of factors is usually required to germinate seeds

of many of the grasses such as bentgrasses, bluegrasses, and the rye-
280 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

grasses. These factors or conditions include alternation of temperatures, exposure to light, and a dilute potassium nitrate solution.

Freshly harvested grass seeds are frequently very exacting in their

requirements, but as the seeds age they will often germinate under a

variety of conditions. The conditions under which freshly harvested

or dormant seeds of certain grasses will germinate are as follows:

Low and wide alternating temperatures, high light intensities, and

dilute concentrations of potassium nitrate. The duration of dormancy

in grass seeds is usually much longer than in cereals, often lasting

from one to several years. This has been shown to be the case in seeds

of Canada bluegrass, some varieties of Colonial bentgrass, and several

of the so-called range grasses or native grasses.

DORMANT EMBRYOS

Embryos of seeds of many species, especially trees, shrubs, weeds,

and native plants, are dormant. The seeds of hawthorn, peach, and

numerous forest trees require a period of after-ripening by stratification in soil, sand, or other moist substratum at approximately 5° C.

for a few months. By isolating the embryos and removing the seed

coat and other structures external to the embryo it has been clearly

shown thatin many instances the dormancy is in the embryo. According to Flemion {19^ W) the dormant portion of the peach embryo is

the epicotyl. Low temperature stratification is necessary for normal

development; otherwise the epicotyl is dwarfed and remains so for

several months before normal growth occurs. There is no dwarfing

of the hypocotyl of the non-after-ripened peach seed which develops

as rapidly as the hypocotyl of fully after-ripened seeds.

The technique of excising and growing embryos has received much

attention in recent years. The technique can be used in research to

determine whether the embryo or some other structure is responsible

for dormancy. In seed testing the technique can be used as a quick

test for certain tree and shrub seeds which ordinarily must undergo

a long prechilling period. The viability of some kinds of seeds can

be determined within 3 to 14 days ; whereas, several months would be

required for stratification and germination tests.

RUDIMENTARY EMBRYOS

Seed stocks of several species in the Umbelliferae (anise, caraway,

dill, parsley, carrot, fennel, and celery) may contain seeds with normal

endosperm and (1) a normal embryo; (2) an immature embryo ;

or (3) no embryo. Some embryos are morphologically immature

and will germinate if kept for long periods under germination

conditions. The occurrence of seeds without embryos but with apparently normal endosperm in this family varies but may reach 50

percent in some instances. In the embryoless seeds there is a cavity

in the endosperm where the embryo would normally be found. According to Flemion and Olson {21) this condition is due to Lygus bugs

feeding on the embryos. Some seeds may be completely empty, containing neither embryo nor endosperm, whereas in others both the

embryo and endosperm may deteriorate.

Defective seeds in corn containing rudimentary embryos and endosperm are reported to be hereditary. Recessive genes which are

lethal or semilethal in character affect the embryo and endosperm

between the time of fertilization and maturity. Defective seeds show
TESTING AGRICULTURAL AND VEGETABLE SEEDS 281

a much lower germination than normal seeds and many of those that

succeed in germinating produce very weak seedlings which lack vigor

and soon die. One type of nonhereditary defective seeds of corn is

attributed to imperfect pollination in which the seeds are embryoless

but contain a normal endosperm. The second type comprises miniature seeds in which there is both a normal embryo and endosperm but

the seeds are greatly compressed—the compression being caused by

the pressure of adjacent normal seeds (Mangelsdorf {85)),

INHIBITING SUBSTANCES

Seed balls of field beet, sugar beet, and Swiss chard contain an inhibitory substance (nitrogenous compounds) which not only retards

germination but which causes discoloration and eventual death of the

primary root, especially when it makes contact with the seed balls.

The symptoms are caused by ammonia released from the organic nitrogen compounds in the seed balls during germination. In seed testing

the seed balls are soaked in water to remove any of the toxic substance

which may be present.

Inhibiting substances are present in the fruits of tomato, gourd, and

other species which prevent the seeds from germinating within the

fruits. When the seeds are planted on substrata moistened with extract from these tissues, germination is suppressed. This suppression can be overcome by heating the extract to 100° C. Kandolph and

Cox {Jf.1) found that the endosperm of iris seeds contains a substance

which inhibits or retards growth when only a part of the endosperm

is left in contact with the embryo. Normal seedlings were produced

by excising the embryos and growing them on nutrient agar.

RETENTION OF VIABILITY IN SEEDS

Most crop seeds have a natural resting period subsequent to harvest.

There are certain environmental conditions which may change this

status. It is well known that during rainy seasons, wheat may start

to germinate while still in the field. Increases in moisture or temperature of stored seeds may increase the physiological processes

within the seed to a degree insufficient for germination but sufficient

enough to weaken the seed and result in loss of viability. The moisture

content within the seeds reaches an equiübrium with the moisture of

the air in which the seeds are stored. It is well known that seeds

stored in the southern part of the United States where the humidity

and temperature are relatively Jiigh, will deteriorate more rapidly

than those stored in the northern States where the temperature and

humidity are relatively low.

EFFECT OF TEMPERATURE

Seeds will remain viable for a longer period of time at low temperatures than at high temperatures, especially at high moisture levels.

Toole and Toole (^6) reported that soybean seed with approximately

18 percent moisture was w^orthless after 1 month of storage at 30° C,

and after 2 years at 10° C, but it showed very little decline in viability

after 6 years of storage at -10°. By reducing the moisture content

of the seeds to approximately 8 or 9 percent there was little loss in

viability at 30° within a year, although the viability dropped off rapidly after that time. Similar seed showed no change within 10 years

when stored at —10° and at 10°.
282 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

EFFECT OF MOISTURE

Different kinds of seed take up different amounts of moisture when

stored at the same relative humidity. Peanuts have been known to

reach a moisture content of 8 percent, sweet corn 13 to 14 percent, and

beans 15 to 16 percent when placed under the same moisture conditions. The fact that seeds should be kept below the critical moisture

level for retention of viability was demonstrated several years ago

when dried Chewings fescue seed was shipped by boat in both cloth

bags and closed canisters from New Zealand to the United States.

Upon arrival in the United States the samples in canisters had an

average moisture content of 7.3 percent and an average germination

of 88.7 percent. The samples shipped in cloth bags had a moisture

content of 11.2 percent and an average germination of 54.5 percent.

Thus, for proper storage of a given kind of seed one must take into

consideration temperature and humidity of the atmosphere in which

the seed is to be stored as well as the initial moisture content of the

seed. The practice of drying seeds, such as hybrid corn, to insure

favorable moisture conditions, as well as storing them at low temperatures, has greatly aided in keeping seeds of these kinds in good condition for future planting purposes.

NATURE OF SEEDS

It is common knowledge that some kinds of seeds retain their

viability much longer than do other kinds. For example, Boswell et

al. (8) found that under warehouse storage conditions the germination of seeds of peanut and onion dropped 72 and 78 percent, respectively, within approximately a year, whereas the germination of lima

bean, kidney bean, tomato, beet, cabbage, and carrot dropped only

about 10 percent, on an average.

DURATION OF VIABILITY

The life span of river maple seeds is only a few days unless they

fall in water or upon moist soil. The moisture content of the seeds

as they fall from the tree is approximately 60 percent. If they fall

upon dry earth or leaves, where their moisture content drops below

30 to 35 percent, they usually die within 6 days. The life span of

garden and farm seeds is usually regarded to be from about 3 to 15

years. Seeds of certain legumes which have impermeable seed coats

have germinated approximately 80 percent after 50 years of storage.

Seeds of Nelumho nucífera estimated to be at least 200 years old

germinated approximately 100 percent when the fruit coats were filed

or otherwise made permeable to water.

It is well known from buried seed experiments that seeds of some

weedy species remain viable after having been buried in the soil for

20, 40, 50, and 60 years. Crop seeds found viable after having been

buried for 20 years were the small-seeded kinds such as timothy, bluegrass, beet, tobacco, celery, and seeds with impermeable seed coats such

as clovers and black locust. Seeds that were dead after 20 years of

storage, or with shorter periods, include the grains, crucifers, cucurbits, onion, asparagus, sunflower, and pine.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 283

MECHANICS OF GERMINATION

In nature, seeds are subject to alternating and fluctuating temperatures, alternate freezing and thawing, moistening and drying, influence of light, action of salts and other chemicals, as well as physical

effects of the soil. All of these conditions are regarded as forcing

agents in the germination of seeds. They probably exert their effects

on the semipermeable membranes of the seed coats, thus modifying

the colloidal nature, permeability, and mechanical resistance of the

coats. Low temperatures for long periods probably aid in the chemical after-ripening of morphologically mature embryos and in the

development of immature or rudimentary embryos. High temperatures act as a forcing agent in the germination of some seeds in which

the oxygen supply is below the minimum required by the embryo.

Because of the low permeability of the seed coat, the minimum oxygen

pressure needed for germination of the embryo is lowered by increased

temperature.

During the natural rest period of crop seeds grown in the north

temperate region in which seeds are harvested in the fall and not

planted until the following spring the seed coats dry out, presumably

modifying their colloidal nature. During this rest period the seed

coat becomes more permeable to water and gases, the seed goes through

certain chemical changes known as after-ripening, and in some instances the immature embryos develop further. When these changes

have not taken place the seed analyst attempts to apply some of

nature's methods, in the laboratory, to bring about the germination

of freshly harvested and other types of dormant seeds.
PATHOLOGICAL CONSIDERATIONS IN SEED TESTING

^ The importance of seed-borne plant diseases is indicated by the

time and materials spent on seed treatment and by the efforts of

research scientists in learning new and improved methods of control.

It can safely be said that the average seed lot in commercial channels

is sold without regard to the seed-borne disease organisms which it

may carry. No doubt, agricultural production in this country would

be greatly increased if the farmer w^ere aware of the sanitary condition of the seed he plants. By sanitary condition is meant the kinds

and relative extent of occurrence of seed-borne fungi, bacteria, viruses,

eelworms, and insects which cause disease and injury.

Some seed lots showing high germination when tested by ofBcial

methods are practically valueless when planted under certain weather

and soil conditions because they are infected with disease organisms

w^hich increase and destroy the seedlings, and plants, or otherwise

reduce the yield. Helminthospormm on cereals is usually not detected in the regular germination test and a high germination percentage may be reported for infected samples. However, if the germination temperature is increased from 20° to 25° or 30° C. and the

seedlings are left in test for 14 or 15 days infected samples may appear

as worthless.

Very few seed-testing laboratories in the United States make any

attempt at testing for the presence of injury or seed-borne diseases.

Perhaps, this situation is due primarily to lack of methods applicable

to routine seed testing by which the specific organisms can be identified. Although research in this phase of seed testing has lagged it

must be recognized that the development of practical methods will

not be an easy task. This should not act as a deterrent to research

but as a challenge, especially when the importance of the problem

is recognized. In order to introduce and carry out a satisfactory

program in this field, seed-testing laboratories will require additional

personnel, equipment, and other facilities and certain legislation will

need to be enacted. Steps in this direction have been taken by some

countries in Europe and by Canada.

SEEDS AS HOSTS AND CARRIERS OF ORGANISMS CAUSING DISEASE

AND INJURY

Fungi are a group of plants lacking chlorophyll or green coloring

matter and are therefore not able to make their own food. They must

obtain food which has already been synthesized. Neither can bacteria, which are one-celled organisms, make their own food. Those

organisms which obtain their food from living plants or animals are

called parasites. Those organisms which obtain their food from dead

plants or animals are termed saprophytes. Micro-organisms which

live internally or externally upon seeds are of primary interest in

seed testing.

284
TESTING AGRICULTURAL AND VEGETABLE SEEDS 285

The micro-organisms proéiaeing seed-borne diseases may be classified as (1) fungi, (2) bacteria, and (3) viruses. Injury and disease^

like conditions may also be caused by nematodes and insects. Fungi

that produce plant diseases may be present in the vegetative stage

as mycelia within the seed or they may be present externally on the

seeds as spores. Bacteria that produce seed-borne diseases have just

one form which serves as both the vegetative and spore stages depending upon the conditions. By cell division each bacterium forms two

new individuals, each of which is capable of starting fresh infection.

Bacteria may divide as frequently as every 20 minutes. Nematodes

or eelworms are microscopic worms which are reproduced by eggs.

They live within, or on the seeds, but usually form galls which

resemble the seed in appearance. Insects whose larval stage feed

upon the embryo of seeds, as the pea weevils or beetles, also reproduce

by eggs. Viruses are ultramicroscopic bodies, too small to be seen

under the compound microscope. They are present in the juice of

plants and are transmitted by aphids, leafhoppers, and thrips sucking

the juice from infected plants and spreading the viruses to healthy

plants.

HOW SEED-BORNE ORGANISMS ARE CARRIED

Internally borne organisms such as fungi which are present in the

form of mycelia within the seed produce such seed-borne diseases

as Anthracnose of bean, Ascochyta of peas, and root-rot or seedlingblight of corn due to Diplodia. Bacteria within the seeds produce such

diseases as black rot of cabbage and bacterial blight of beans. Nematodes such as Tylerwhus dipsaci which are present within the seeds

produce injury as stem nematode injury of wheat, alfalfa, and red

clover. Viruses are reported to be transmitted by seeds as well as

by other means. Mosiac due to seed transmission of viruses has been

reported for alfalfa, red clover, white clover, lettuce, cucumber, bean,

and lima bean.

Externally borne organisms are those in which the spores are present

externally on the seeds and which produce such seed-borne diseases

as bunt of wheat, covered smut of barley and sorghum, and downy

mildew of spinach. Bacteria present on the exterior of seeds produce

bacterial pea blight and other diseases. Nematodes may be carried

externfilly on seeds but they are usually carried in gall tissue along

with the seeds as in wheat samples.

RELATION OF HOST AND PARASITE

Some diseases have a systemic type of infection. The pathogen

lives in the plant throughout its life. Examples are: Ustilago spp.

which produces loose smut of wheat and barley and Hehninthosporium

grar)iineuin which produces stripe of barley. Ustilago nuda (Jens)

Rostr. is a deep-seated fungus of the systemic type, and produces the

seed-borne disease known as loose smut of barley. The smutted spikes

containing chlamydospores emerge from the boot slightly ahead of

the healthy spikes. Wind-borne chlamydospores lodge on the healthy

barley flowers and germinate, followed by conjugation of the haploid

cells of the promycelium that form binucleate mycelia, which penetrate the stigma of the ovary. The mycelium remains dormant where

957116—52 20
286 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

it is present chiefly in the scutellum of the infected seed. When the

infected seed is sown and germinates, the development of the mycelium

is also resumed. The mycelium grows right along with the growingpoint tissues of the barley shoot and eventually develops spores in

the floral parts prior to emergence of the spike.

Gibherella spp. and Fmarium spp. produce a local, nonsystemic type

of infection on cereals and grasses. The mycelia, which are carried

within the seed infect the seedling and produce seedling blight and

root rot. In addition, healthy seedlings may be infected from the

mycelia, conidia, and perithecia developed in crop residue. Head

blight is usually due to infection from conidia and ascospores of crop

residue. Primary infection of the developing seeds occurs early in

the flowering stage and in the beginning of the ripening of the seeds.

Secondary infection of the seed occurs slightly later in the development of the seed from air-borne conidia and mycelia. The infected

seeds are more or less scabby. The scabbiness is due to mycelial tufts

growing out from the seed coats. The more severely infected seeds

are shrunken and light brown in color.

EFFECT UPON THE HOST SEED

DISEASES AND ORGANISMS WHICH MAY BE IDENTIFIED PRIOR TO GERMINATION

The effects of insects and some seed-borne pathogens can be detected

on seeds by microscopic examination and in some instances by the

aid of a stereoscopic microscope.

Insect injury,—Insect injury due to weevils, beetles, and moths

that spend the larval stage within the seed feeding upon the embryo,

can usually be detected by the holes left in the seed as the insects

emerge and by the resulting injury to the seedlings upon germination.

Sclerotia.—Sclerotia, which are the overwintering stage of some

fungi, are hard bodies consisting principally of mycelia which replace the seed. The ergot sclerotia from the fungus, Clamceps purfurea is found in rye, wheat, Agrostis, Holcus^ and timothy. The

sclerotium in rye is curved, grayish violet in color, and two or three

times as long as the rye kernel. Sclerotia produced by the fungus

Glaviceps paspali and 0, yanagawaensis have been found in seed

samples of Paspalum dilatatwm and Zoysia japónica^ respectively.

Seeds of red clover, white clover, and possibly other species, may be

infected with the fungi Sclerotinia and Typhula. Small black or

dull brown sclerotia and infected seeds that appear immature,

shrunken, and grayish pink in color may occur in seed samples.

Diseased seed.—Eyegrass samples frequently contain large percentages of infected seed owing to the fungus Phialea temulenta which

causes blind-seed disease. Badly infected seeds do not germinate.

Healthy ryegrass seeds are bright as compared with diseased seeds,

which are opaque under the diaphanoscope. If the seeds with glumes

removed are placed in a drop of water on a slide the elongated hyaline

macrospores will float from the caryopses and can be identified under

a binocular microscope. In the field, the severity of the disease and

whether it is profitable to harvest the crop can be determined at the

honey dew or conidial stage, which is characterized by a pink slime

found between the young ovules and the glumes.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 287

Pycnidia,—Pycnidia of Septoria apii^ causing late blight of celery,

can be detected under a binocular or stereoscopic microscope. These

pycnidia are small, black, globose structures on the ribs of the celery

seeds.

Covered smut of cereals and grasses,—^Bunted grains of wheat and

covered smut grains of barley and oats in which the so-called grains

are full of spores are indicative of their respective diseases. Samples

of seed may also be infected when bunted or smutted grains are not

present, in which case the smut spores are present on the exterior of the

seeds. The disease may be identified by shaking 100 seeds in a test tube

of water and evaporating the liquid and then examining the concentrate under a compound microscope. Loose smuts in wheat, Ustilago

tritici (Pers.) Eostr., and barley, Ustilago nuda (Jens.) Rostr., are

presentin seeds as deep-seated mycelia and therefore cannot be detected

by microscopic examination.

DISEASES FOR WHICH EXAMINATION SHOULD BE MADE AT THE END OF THE

GERMINATION TEST

Anthracnose of bean produces brownish-gray spots with a light

center on the seeds. The spots can readily be seen on light-colored

dry seed but not on dark seeds. The spots of Ascochyta spp. on peas

are not easily seen when the seeds are dry. Diplodia spp. produce

badly rotted seeds of corn. Fusarium spp. and Gibherella spp. produce

discolored seeds of wheat and barley. These symptoms are not usually

sufficient for the determination of the disease; therefore, moist germinating conditions are provided in order that the growth of the fungus

may be resumed to produce fruiting structures, including spores, for

identification.

Peas.—^Ascochyta blight is probably the most serious of the diseases

occurring on peas and is due to three different pathogens : Ascochyta

pisi Lib., A, pinodella Jones, and Mycosphaerella pinodes (Berk, and

Blax.) Stone. The fungus consists of a dense white or gray mycelium and develops from the diseased seed within 4 to 7 days ; the lightbrown pycnidia develop within about 10 days. The spores within the

dark-brown pycnidia are one- or two-celled and are not curved. They

vary in color from pink to salmon or carrot red and rarely exceed 15 by

4.5 microns in size (Crosier {H)).

Fusarium wilt is caused by the fungus Fusarium orthoceras Appel,

and Wr. yar. pisi Linford. Other species of Fusarium are also present

on germinating seeds. The mycelium of the genus Fusarium is a

fluffy white to pink or red as contrasted with the dense white or gray

mycelium of Ascochyta, The spores are 0 to 5 septate, elliptical or

slightly curved, and range from 27 to 45 by 4.5 to 5.5 microns in size.

Beans,—Anthracnose caused by the fungus OoUetotrichum lindemuthianum (Sacc. Magn.) Briosi Cav. is one of the important bean

diseases. It penetrates the seed coat, enters the cotyledons, and produces brown to yellowish sunken lesions on the seeds. Fruiting structures bearing single-celled conidia are differentiated within the lesions.

The individual conidia are hyaline nonseptate, oval to oblong, straight

or slightly curved, range from 13 by 4.4 to 22 by 5.3 microns in size,

and are held together by a mucilaginous pink-colored excretion.

Seedlings developing from infected seed may be stunted or decayed

and are classified as abnormal. Anthracnose occurs on practically
288 AGRICULTURE HANDBOOK KO. 30, U. S. DEPT. OF AGRICULTURÎi

all varieties of garden bean and on most of the dry-shelled field varieties (Harter and Zaumeyer (^^) ).

Discolored bean seed may be due to bacterial blight which is caused

by three organisms as follows : Common blight, Xanthomonas phaseoli; halo blight, Pseudomonas medicaginis var. phaseolicola; and wilt,

Corynebacteriunh ftaccwnfaciens. The first two frequently appear together and cannot readily be distinguished. The bacteria are present

under the seed coat. Infected seeds appear shrunken, wrinkled, rotted,

or discolored. They may be discolored only at the hilum. The discoloration can readily be detected on light-colored seeds but not on

dark-colored seeds. When the seeds germinate, the bacteria invade the

cotyledons. Frequently lesions are formed on the cotyledons, cotyledonary nodes, or the primary leaves, and these lesions enlarge and

coalesce with similar infected areas. The dry, wilt-infected seeds of

white-seeded varieties of beans are conspicuously yellow owing to

bright yellow masses of bacteria which are clearly visible through the

seed coat but the bacteria are not easily recognized in the dark-seeded

varieties. Wilt is primarily a vascular parasite in which the vascular

bundles become plugged, thus cutting off the supply of water and causing the seedlings to wilt and die if attacked when only 2 or 3 inches

high. The color of the exúdate from the common blight organism is

yellow and from the halo blight organism is light cream or silver

(Harter and Zaumeyer {2ß)),

Corn,—Diplodia spp. and Gibherella spp. are two of several fungi

producing seed-borne diseases in corn. The fungi Diplodia spp.,

produce dry rot of the ear and stalk and root rot of the corn plant.

The infected kernels are grayish brown in color with small black

pycnidia, each containing two-celled spores. The two-celled spores

are 25 to 30 by 6 microns in size and are olive in color. White or

grayish mycelia emerge from the kernel on moist substratum at the

designated temperatures for germinating seeds of corn (Koehler and

Holbert {SI)), Gihherella zeae Fetch produces seedling blight, pink

ear rot, and stalk rot of corn. Itis characterized on the moist seed bed

in the germinators by reddish coloration of the seed coats of the kernel.

The conidial stage is Fusarium graminearu/m Schw. The mycelium

is white or pink in mass. The hyaline, sickle-shaped spores (macrocondia) are three to five septate and measure 41 to 60 by 4.3 to 5.5

microns in size (Koehler and Holbert {SI) ).

Wheats harley^ rye^ and oats,—Fusarium spp. cause root rot or

seedling blight of the cereal seedlings. Helminthosporium spp. cause

stripe disease {H, gramineum) and spot blotch (H, sativum). The

latter also causes seedling blight or a browning of the coleoptile and

roots which later become soft and watery resulting in death of the

seedlings. In the laboratory the symptoms of these diseases can be

detected more readily at warmer temperatures of 25° C. or higher

than at the usual germination temperatures of 20° or lower, at which

cereal seeds are usually tested. It takes 10 or 14 days before spores

of Helminthosporium spp. are formed whereas the regular germination test of wheat, barley, and rye is terminated within 7 days, and

oats within 10 days. Tile mycelium which emerges from the kernels

infected with Fusarium spp. is white or pink and the spores (conidia)

are hyaline, curved, and have three to five septa. The spores are

similar to those described for the conidial stage of Gibherella zeae
TESTING AGRICULTURAL AND VEGETABLE SEEDS 289

Petcli under the heading corn. Helmmthosporium sativum causes

"black point," in which the embryo ends of the kernels of

wheat and barley are blackened, and spot blotch disease which appears later in the field. The conidiophores of this species may

bear 2, but usually 4 or 5, spores. The spores are curved, being

widest in the middle, have 1 to 10 transverse septa, are reddish to

dark olive-brown in color, and vary in size, depending upon

the environment. Stripe disease due to H, gramineiim Kabenh. is a

systemic disease. The mycelium is carried in the embryo of the

seed. On moist blotters the mycelium emerges abundantly and is

gray through olive to black. The conidia are hyaline to yellowishbrown, straight, subcylindrical to slightly tapering with rounded ends.

They are 1 to 7 septate without constrictions at the septa and average

105 by 20 microns in size. Helminthosporium victoriae infects derivatives of the Victoria variety of oats. H. avenae causes injury to

seedlings of various lines of oats. The symptoms of these diseases

on the seedlings in moist germinators at 25° C. or higher are browning

of the coleoptiles and roots. The spores form within 10 to 14 days

and arise in groups of 2 to 12 at the ends of conidiophores. The spores

are cigar-shaped or cylindrical bodies.

Doyer {18) describes the Hiltner method for detecting Fusanum

spp. and Helminthosporium spp. that attack cereal seedlings. The

Hiltner method is also used in differentiating between H, gramineum

and H, sativum that attack cereal seedlings. The cereal seeds are

sown in ground brick particles about 3 cm. below the surface. The

test is terminated after 14 days. The heavily infected seedlings are

apically curled and not able to penetrate the brick dust. The less

heavily infected seedlings are straight with brown-discolored coleoptiles and roots. Those seedlings infected with Fusariwn spp. twist

from^ the bottom upward whereas those infected with Flelmmthosporium spp. begin the twisting or winding farther up on the seedling.

Also the concave side of the Helminthosporium-miected seedlings

are discolored black and contain the fungus. Stripe disease, caused

by H. gramineum^ is characterized by long brown stripes along the

stem. Muskett (S9) reported that irradiation of cereal seeds with

white light IS beneficial in producing spores (conidia) in Helminthosporium avenae. Replicates of 15 oat seeds are sown in 100-mm. Petri

dishes on moist filter paper at 22° C. On the fourth day the lids are removed from the Petri dishes and the dishes are placed under a Hanovia

sun lamp, at a distance of 1 foot, for 20 minutes. After 9 days the

material is examined for the presence of conidia of H, avenae,

Crucifers,—OnQ of the most important diseases of cabbage and

of other cruciferous species is due to Alternaria Irassicae (Berk.)

Sacc. and Alternaria circinans (Berk, and Curt.) Bolle. The symptoms are a dark discoloration at the base of the stem extending down

the hypocotyl. The cotyledons may be entirely rotted if the seed

coats persist. When the seed coats do not persist, the cotyledons may

have numerous to few black spots or necrotic areas on the cotyledons.

Discoloration is often evident on the dorsal side of the cotyledons

when no abnormalities are present on the axial side. The mycelium

IS dark to black. The conidia of A, Irassicae are obclavate, light olive

brown, and long-beaked, and have 5 to 12 transverse septa and

a tew longitudinal septa. They are 100 to 238 by 16 to 35 microns in

size (Crosier {15)),
290 AGRICULTURE HANDBOOK NO. 30; U. S. DEPT. OF AGRICULTURE

Pod spot on radish is due to 3 pathogenic species of AUernaria:

A. raphani^ A, irassicae^ and A. oleraceae. The saprophytic form

A, tenuis may also be present. However, A. raphani is the most common form and is extremely pathogenic. The usual symptoms of the

disease on the seedlings are olive to gray or black, round, raised

areas on the cotyledons and at the base of the cotyledons. There

are also lesions on the hypocotyl and the roots of the seedlings. When

the seed coat adheres to the base of the hypocotyl, this area becomes

soft and decayed. The conidia of A, raphani are borne in chains.

They are olive brown and muriform, and have three to nine transverse

septa and numerous longitudinal septa. They are 55 to 135 by 14 to 25

microns in size (McLean {S6) ; Groves and Skolko (25)). The

Altemaria species have been studied in detail by Neergaard (Jt^O) who

has transferred AUernaria radicina which attacks carrot seed to

Stem,phyliwrb radicinunv, Phoma Ungarn producing black leg of cabbage and other cruciferous plants is a disease of major importance. It

is characterized by dark sunken stripes on the hypocotyl of the seedlings. The dark-colored pycnidia produce small, oval spores which

ooze out of the pycnidia and in mass are pink. Individual spores are

hyaline, nonseptate, and 1 to 2.5 by 3 to 6 microns in size (Walker

Beet,—One of the most important diseases of beets is the result of

the fungus Phoma letae Frank, which causes root rot. At the end

of the 14-day germination test dark pycnidia with small, oval, onecelled spores oozing out can be observed under a binocular. The roots

of the diseased seedlings are dark brown in color. This condition

must not be confused with the discoloration of the radicles caused by

toxic nitrogenous substances in the seed balls.

Flaw,—The seed-borne organisms attacking flax seed are CoUetotrichum Unicola (seedling blight), Polyspora Uni (stem break and

browning), Botrytis cinérea (gray mold), Phoma sp. (foot-rot), and

Fmarium Uni (wilt). Muskett {S9) reports that the best medium

for the detection of these diseases is a 2-percent malt extract agar.

The seeds are planted on the agar solution in Petri dishes and incubated at 22° C. for a period of 5 days. The fungi are identified

by the type of colonies produced on the agar solution. When tested

in moist germinators, identification of the spores is usually necessary.

Cotton,—One of the most important diseases of cotton is Anthracnose due to the fungus GlomereUa gossypii Edg. The infection is

usually from external spores on the seed. Damping off of the seedlings may occur. The symptoms are lesions on the cotyledons, stems,

and leaves, and rotting. Small reddish to light-colored spots or

necrosis of the marginal tissues is common on the cotyledons. Similar

oblong brown cankers occur on the hypocotyl and young stem. Girdling of the stem occurs under high humidity. The conidia develop

on the mycelium or in acervuli. The conidia are cylindrical, generally straight, hyaline, one-celled, 3.5 to 7 by 12 to 25 microns in

size, and are held in a mucilaginous mass.

Fusarium wilt of cotton is due to the fungus Fusarium oxysporum

f. vasinfectum (Atk.) Snyder and Hansen which causes wilting of

the leaves and premature death in some varieties. The sickle-shaped,

macroconidia are hyaline, three, four, or five septate, and 3 to 4.5

by 40 to 50 microns in size. Microconidia are unicellular and ellipsoidal. They are 2 to 3.5 by 5 to 12 microns in size (Dickson {17) ).
TESTING AGRICULTURAL AND VEGETABLE SEEDS 291

Clover and Alfalfa,—The fungus Botrytis anthophila has been

found to cause a mold on seeds of red and Ladino clovers in Oregon.

Infected seeds are usually shriveled and dull brown to gray pink in

color. Most infected seeds failto germinate. Sclerotinia spermophila^

described on seed of white clover in Great Britain, is possibly another

stage of the same fungus. Diseased seeds kept moist in a germinator

for 5 days produce sclerotia. Sclerotia which overwinter in the field

produce stromatal heads that give rise to perethecia and ascospores.

The "blackpatch" disease, caused by an unidentified fungus is carried

on the surfaèé of and within the seeds of red clover. This disease can

materially reduce seed yield and cause seedling blight. During germination the large mycelia can destroy seedlings and spread to adjacent ones before germination is complete.

Celery,—-A common seed-borne disease of celery is late blight. It

is due to the fungi Septoria apii (Briosi and Cav.) Chester and S,

apii-graveolentis Dorogen. Late blight produces necrotic spots on the

leaves and lesions on the petioles. It has been mentioned earlier that

the pycnidia which are present on the ribs of the seed can be detected

under a binocular microscope. When the seeds have lain in water for

a short time the numerous, long, slender, filiform, septate, spores

emerge. The conidia have several septations and are straight to

slightly curved. The conidia of the first-named Septoria are 22.5 to

58.5 by 1.5 to 3.0 microns in size, whereas those of the latter are somewhat shorter, 13.5 to 34.2 by 1 to 2.5 microns.

Rice,—Seedling blights and culm rot are diseases of major importance affecting rice. Gibberella blight or "Bakanae disease" is due to

Gihherella fujikuroi (Saw.) Wr. and G. zeae Scliw. Fetch. The conidial stage of the former fungus is Fusarium moniliforme (Sheld.) and

of the latter, Fusarium. gramineariim Schw. Another seedling blight

disease, Helminthosporium blight, is caused by Gochlioholus {Ophioholus) miyaheanus Ito and Kuribay. Symptoms of these seedling

blights include reduction of germination, and browning of the roots

and the coleoptiles of the shoots which results in reduced vigor or

killing of the seedlings. These diseases also produce kernel blight.

The Gibberella blight has been isolated from yellow and pink discolored seeds and the Helminthosporium blight from brown necrotic

areas on seeds.

The culm disease due to the fungus Leptosphaeria salvinii Catt.

causes lodging and lightweight grain. Black discolored areas appear

on the culms and black sclerotia develop inside the leaf sheath and

later in the culm. The black sclerotia are carried with the seed. The

spherical sclerotia are black and 230 to 270 microns in diameter. The

conidial stage is Helminthosporium sigmoideum Cav. The conidia

are wide in the center, taper toward each end, slightly curved, and

typically triseptate.

The Committee on the Determination of Seed-Borne Organisms of

the International Seed Testing Association has proposed methods for

determining the presence of certain seed-borne diseases and injury

conditions. A report by Crosier {16) includes a list of "infectious

entities" (seed-borne fungi, bacteria, insects, and eelworms) for each

of several kinds or groups of seed. This report which was prepared

primarily by Dr. W. C. Crosier, New York Agricultural Experiment

Station, Geneva, N. Y., and the late Dr. L. C. Doyer, Waginengen,
292 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

The Netherlands, was accepted by the International Seed Testing

Congress held at Washington, D. C., May 1950, and is being incorporated into the International Rules for Seed Testing by the Rules

Committee. These methods, with minor modifications, and the list

of infectious entities are given in the following pages.

METHODS

In general, the procedure shall consist of macroscopic examination

of the seed sample, microscopic examination of the seed sample, and

examination of the seeds and seedlings during or at the end of the

germination test.

I. Upon receipt the whole sample or, in case the sample may be too large, a

portion of it, should be inspected for the presence of bunt kernels, ergots,

fragments of smutted seeds, sclerotia and discolorations due to pathogenic

organisms. Fungi also may be present in chaff, straw, or other inert

matter carried with the seed. Attention should also be paid to the fact

that the seeds may show round holes out of which insects such as Bruchus

spp. may have emerged, in which case larvae or weevils still in a living

state may be found in the sample. Furthermore, the presence of storage

pests such as granary moths (larval or adult stage) and moths, or mites,

should also be determined. Specifically the sample shall be examined

for the presence of:

A. Ergots, sclerotia, smut-kernels, etc.

B. Discolorations and blemishes indicative of bacteria or fungi

{Diplodia zeae in corn, Xanthomonas pJiaseoU in beans, etc.).

C. Damage and invasion by insects and other animal life {Bruchus

spp., Tylenchus spp., etc.).

I). Stored seed pests (granary weevils, mites, etc.).

II. The seed sample shall be examined microscopically for the presence of pests

and conditions as indicated below.

A. Spores adhering to the seeds {Polyspora Uni, TilleUa spp., etc.).

Fungus spores, intermingled with the seeds or adhering to them,

may be identified by vigorously shaking 100 seeds or more in a test

tube with a little water plus a detergent or alcohol. The washings

should be either centrifuged or evaporated to a few drops before

being examined microscopically for the presence of fungus spores.

This is particularly applicable in the case of TilleUa spp. In the

case of other spores such as Fusarium spp. these pathogens will be

more easily detected in the germination test, during which the

fungi present usually develop their own characteristic fructifications on the invaded tissues.

B. Disease fungi with distinctly recognizable forms (acervuli of

ColletotricJium spp., pycnidia of Beptoria petroselini, etc. ). In order

to identify the presence of acervuli, pycnidia, perithecia, or any

other typical stage of fungus infection present on the seed, about

50 or ioo seeds should be examined by means of a stereoscopic

microscope. In this way the percentage of such infections may be

determined.

III. The sample shaU be examined during, or at the end of, the germination test

for the following pests and conditions:

A. Pathogenic bacteria and fungi in, or growing out of, the seeds (Examples : Alternaría hrassicae, Xanthomonas campestris, etc.). With

regard to fungi which develop in a characteristic manner in moist

surroundings, it is desirable to arrange the seeds in the germination medium in such a way that they are not in contact with each

other ; in the case of cereals a substratum of folded blotting paper

is satisfactory. Beans and peas which are more inclined to roll,

should be arranged on substrata consisting of a sheet of moist
TESTING AGRICULTURAL AND VEGETABLE SEEDS 293

blotting paper, laid in a tray with perforated bottom (sizes about

27 by 10 cm.). On this blotting paper about 50 beans or peas are

evenly distributed and covered with another sheet of moist blotting

paper. Should any symptoms of metallic poisoning appear as a

result of using metal trays, it would be advisable to use bakélite

or plastic trays. The bottom of the trays must be perforated so

as to avoid the collection of water.

Beet and flax seeds should be tested in trays similar to those just

described, but in the case of beet seeds the trays should remain

uhcovered. One hundred seeds of beet and flax should be used. In

the determination of pests the seeds should not be soaked beforehand. An exception in this respect is made for beans (Phaseolus

spp. ) in that half of the seeds are soaked prior to testing. In this

way the degree of resistance against unfavorable conditions of

each lot can be stated. Beans of high quality are not injured by

soaking whereas dead or decadent seeds often disintegrate or

become mucilaginous through bacterial action. Broad or fava beans

(Vicia fada) must always be soaked in advance, otherwise germination is seriously delayed. Temperature and moisture conditions similar to those used for ordinary germination tests should

be maintained except that temperatures of 25° or 28° C. should be

used for cereal. The sanitary tests for beans, flax, and pea seed

may be terminated after 5 or 6 days ; for Phoma-intected beet seed

it is desirable to leave the seeds in the germinator for about 12

days ; and for cereals, 10 to 14 days.

Although infection by Ascochyta, Botrytis, Colletotrichum lindemuthianum, Fusarium, and StempJiylium may be identified with

the naked eye, a stereoscopic microscope (X 20) is required

for the determination of Colletotrichum and Polyspora on flax,

Colletotricnum on spinach, and Phoma betae on beet seeds. A compound microscope is necessary for identifying the spores.

Disinfection or disinfestation studies may be undertaken in conjunction with the examination for pests. The seeds are treated

either with a dust or a suspension. The sanitary test with this

treated seed is made as previously described. Insofar as the microorganisms are superficial, they will be eliminated for the greater

part by eflicient treatment, but in cases in which these infections

are more deep-seated, such as Ascochyta spp. in peas, or Colletotrichum lindemuthianuTYh in beans, disinfection will not, as a rule,

be complete.

B, Insects inside the seeds including the larval stage, and evidence

of those that may have emerged.

At the end of the test the seeds may be cut so as to reveal

any abnormalities that may be present in their interiors. In

this way insects in the larval or adult stage may be found inside

the seeds. When Chalcididae are found in conifer or other tree

seeds, the germination power is always completely lost in consequence of their activities. Beans and peas, invaded by Bruchus

spp., may still germinate if the germ has escaped injury by the

insect.

C. Physiological disturbances (marsh spot in peas).

The symptoms of "marsh spot" may be found by cutting peas

transversely to the cotyledons ; if typical spots occur special attention should be paid to the plumules to determine whether these

also show brown discolorations of a serious nature.

PARTIAL LIST OF PESTS AND INJURY CONDITIONS

As each seed species may carry its own particular type of infectious

entities short lists of the most characteristic of these entities are given

below. The Eoman numerals and capital letters preceding the names

indicate the methods that are applicable for determining their presence as given in the paragraphs under "Methods."
294 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

Bean (Phaseolus spp.)

I B. Colletotrichum lindemuihianum (Sacc. & Magn.) Briosi & Cav., Pseudomonas phaseolicola (Burk.) Stapp & Cotte, and Xanthomonas spp.

I C. Acanthoscelides obtectus Say.

Ill A. Ascochyta holtshauseri Sacc, A, phaseolorum Sacc, Botrytis cinérea Fr.,

Cercospora cruenta Sacc, Colletotrichum lindemuihianum (Sacc & Magn.)

Briosi & Cav., C. truncatum (Schw.) Andrus & Moore, Corynehacterium

flaccumfaciens (Hedges) Dowson, Diaporthe phaseolorum (Cke. & Ell.)

Sacc, Fusarium spp., Macrophomina phaseoli (Maubl.) Ashby,

Pleospora herharum Rab., Pseudomonas viridiflava (Burk.) Dowson,

Rhizoctonia solani Kuehn, and Sclerotinia sclerotiorum (Lib.) DBy.

Beet

II A. Uromyces betae (Pers.) Lev.

Ill A. Coprinus lagopus Fr. and Phoma betae Frank.

Broad or fava bean

I C. Bruchus atomarius (granarius) L., and B. rufimanus Boh.

Ill A. Ascochyta pisi Lib., Fusarium spp., and Ascochyta fabae Spegazzini.

Ill B. Bruchus atomarius (granarius) L., and B. rufimanus Boh.

Cabbage and other Cruciferae

I A. Sclerotinia sclerotiorum (Lib.) Dby.

Ill A. Alternaria brassicae (Berk.) Sacc, A, brassicicola (Schw.) Wilts., Phoma

lingam Desm., Mycosphaerella brassicicola (Duby) Oudem., and Xanthomonas campestris (Pammel) Dowson.

Carnation and other Caryophyllaceae

II A. Puccinia dianthi DC. or P, arenariae (Schum.) Wint.

Ill A. Alternaria dianthi F. L. Stevens & Hall, A. dianthicola Neerg., A. gysophilae Neerg., Botrytis cinérea Fr., and Rhizoctonia solani Kuehn.

Carrot

III A. Alternaria porri (Ell.) Neerg. f. sp. dauci, Septoria daucina Brun., and

Stemphylium radicinum (Meier, Drechs. & Eddy) Neerg.

Celery

II B. Septoria apii (Briosi & Cav.) Chester and S, apii-graveolentis Dorogin.

Ill A. Stemphylium radicinum (Meier, Drechs. & Eddy) Neerg.

Cereal or small grains

I A. Claviceps purpurea (Fr.) Tul., Tilletia caries (DC.) Tul., T.foelida (Wallr.)

Liro, Ustilago crameri Koern., U. hordei (Pers.) Lagh. and U. kolleri

Wille.

I B. Gibberella zeae (Schw.) Petch and Helminthosporium sativum Pam., King

& Bakke.

I C. Tylenchus tritici (Stein.) Bast.

I D. Granary weevils, moths (both larvae and adults), and mites.

II A. Sclerospora graminicola (Sacc) Schroet., Titletia spp., Urocystis occulta

(Wallr.) Rab., and Ustilago spp.

Ill A. Dilophospora alopecuri Fr. in wheat, Fusarium spp. Helminthosporium

avenae Eidam, H. victoriae Murphy and Meehan, and Pseudomonas

coronafaciens Elliott in oats, Helminthosporium gramineum Rab. and

H. teres Sacc. in barley, Fusarium spp. and Helminthosporium sativum

in barley and wheat, and Xanthomonas spp. in barley, oats, rye, and

wheat.

China aster

III A. Alternaria zinniae Pape, Ascochyta asteris (Bres.) Gloyer, Botrytis cinérea

Fr., Cladosporium spp., Fusarium conglutinans var. callistephi Beach,

Phoma glomerata (Corda) Woll. and H., Rhizoctonia solani Kuehn, and

Septoria callistephi Gloyer.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 295

Clover and alfalfa

I A. Botrytis cinérea Fr., Sclerotinia sclerotiorum (Lib.) DBy., S. trifoliorum

Erikss. and Typhula trifolii Rostr.

I B. Sclerotinia spermophila Noble.

I C. Bruchophagus gihbus Boh. and Dasyneura leguminicola Lint.

Ill A. Ascochyta caulicola Laub., A. imperfecta Pk., A. lethalis EIL & C. Barth.,

Botrytis antophila A. Bond, Cercospora medicaginis E. and C, zehrina Pass.,

Colletotrichum trifolii Bain, and Essary, Fusarium spp., Gloeosporium

caulivorum Kirch., Sphaerulina trifolii E. Rostr., and Stemphylium botryosum Wallr.

Corn (maize)

T B. Diplodia frumenti EU. & Ev., D. zeae (Schw.) Lev.

I D. Ahasvérus adventa WaltL, Sitophilus oryza L., Sitotroga cerealella Oliv.,

Tribolium spp. et al., Tenebroides mauritaniens L.

II A. Nigrospora sphaerica (Sacc.) Mason and Bacterium stewartii E. F. Sm.

Ill A. Diplodia spp., Fusarium spp., Gibberella zeae (Schw.) Fetch., and Pénicillium spp.

Cotton

I A. Nematospora spp.

Ill A. Ascochyta gossypii Syd., Diplodia gossypiana Cooke, Fusarium spp. Fusarium oxysporum f. vasinfectum (Atk.) Snyder and Hansen, Glomerella

gossypii Edg., and Xanthomonas malvacerum (E. F. Sm.) Dows.

Flax

II B. Ascochyta linicolal^SkOum. Sind Vass., Polyspora Uni LafiPerty, and Mycosphaerella linorum (Wr.) Garcia Rada.

Ill A. Alternaria linicola Groves and Skolko, Ascochyta linicola Naoum. & Vass.,

Botrytis cinérea Fr., Colletotrichum. linicolum Pethy. and Lafferty, Fusarium Uni Bolley, and Melampsora Uni DC.

Grass

I A. Claviceps paspali F. L. Stevens & Hall, and C, purpurea Fr.

I B. Corynebacterium rathayi (E. F. Sm.) Dows., and C. microcephala (Wallr.)

I C. Tylenchus sp.

II A. Phialea temulenta Prill. & Delacr., Ustilago striiformis (West.) Niesst.

and other Ustilago spp.

Ill A. Curvularia spp., Fusarium spp., Helminthosporium spp., Phialea temulenta Prill, and Delacr., and Phoma glomerata (Corda) Woll. and H.

Parsley

II B. Septoria petroselini Desm.

Ill A. Stemphylium radicinum (Meier, Drehs. & Eddy) Neerg.

Pea

I C. Apion vorax Hbst., Bruchus pisorum L., and Grapholitha spp.

Ill A. Ascochyta pinodella L. K. Jones, A. pisi Lib., Botrytis cinérea Fr., Cladosporium pisicola Snyder, Colletotrichum pisi Pat., Fusarium spp., Mycosphaerella pinodes (Berk. & Blox.) Vest., Pleospora herbarum Rab.,

Pseudomonas pisi Sackett, Rhizoctonia solani Kuehn, Septoria pisi West.,

TTT T» Sclerotinia sclerotiorum (Lib.) DBy., and Stemphylium botryosum Wallr.

Ill B. Apion vorax Hbst. and Bruchus visorum L.

Ill C. Marsh spot.

Peanut

I A. Sclerotinia minor Jagger, and Sclerotium rolfsii.

Ill A. Cercospora personóla.
296 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Pepper and tomato

II A. Phytophthora capsici Leonian, P. infestans (Mont.) DBy., P. omnívora

DBy., and Rhizoctonia solani Kuehn.

Ill A. Alternaría solani (Ell. and G. Martin) Sor., Colletotrichum phomoides (Sacc.)

Ches., Cladosporium fulvum Cooke, Corynehacterium michiganese (E. F.

Sm.) Jens., Didymella lycopersici Kleb., Fusarium lycopersici (Sacc.)

Wr., Gloeosporium piperalum Ell. and Ev., Phoma destructivora Plowr.,

Phytophthora spp., Pseudomonas pundulans Bryan, P. tomato (Okabe)

Burkh., Vermicularia capsici Syd., and Xanthomonas vesicatoria

(Doidge) Dowson.

Rice

I A. Leptosphaeria salvinii Catt., Sclerotium sp., and Ustilaginoidea virens.

II A. Neovissa hórrida (Takahashi).

Ill A. Alternaria sp., Cercospora oryzae Miyake, Cochilioholus miyaheanus Ito

and Knribay, Gihherella fujikuroi (Sow.) Wr.,G. zeae (Schw.) Fetch., and

Piricularia oryzae.

Soybean

I A. Sclerotinia sclerotiorum (Lib.) DBy.

I B. Pseudomonas glycinea (Coerper) Stapp and Xanthomonas phaseoli var.

sájense (Hedges) Starr & Burkh.

II B. Glomerella glycines (Hori) Lehm. & Wolf and Phomopsis sojae Lehm.

Ill A. Cercospora diazu Miura, Cercosporina kikychii Mats. & Tom., Diaporthe

sojae Lehm., Peronospora manchurica (Naoum.) Syd., Phomopsis sojae

Lehm., Sclerotinia sclerotiorum (Lib.) DBy., and Septoria ghjcines

Hemmi.

Tree

I C. Several species of Chalcididae. a ^ •

III B. Chalcididae spp., Megastigmus spp. in conifers, M. aculeatus Swed. m rose,

Syntomaspis druparium Boh. in apple and pear, and Endothia parasítica

(Murr.) A. & A. in chestnut.

Vetch

I C. Bruchus hrachialis Fahr.

Ill A. Ascochyta pinodella L. K. Jones, A. pisi Lib., Colletotrichum viUosum

Weimer, and Protocoronospora nigricans Atk. & Edg.
LITERATURE CITED

(1) ABERG, E., and WIEBE, G. A.

1946. CLASSIFICATION OF BARLEY VARIETIES GROWN IN THE UNITED STATES AND

CANADA. U. S. Dept. Agr. Tech. Bui. 907. 190 pp.

(2) ANDERSEN, A. M.

1933. THE EFFECT OF CARBON DIOXIDE AND SOME OTHER GASES ON THE GERMINATION OF SEEDS OF Poa compressa L. Amer. Jour. Bot. 20: 678

supp.

(3)

(4)

1938. MOISTENING AND DRYING AS A PRETREATMENT IN GERMINATING SEEDS

OF Poa compressa. Proc. Assoc. Off. Seed Anal. 30: 246.

1938. COMPARISON OF METHODS USED IN GERMINATING SEEDS OF Poa COmpressa. Internat. Seed Testing Assoc. Proc. 10: 307-315.

(5) ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS.

1950. OFFICIAL METHODS OF ANALYSIS. Published by the Assoc. Off. Agr.

Chem., P. O. Box 540, Benjamin Franklin Station, Washington 4,

D. C.

(6) ASSOCIATION OF OFFICIAL SEED ANALYSTS.

1949. RULES FOR SEED TESTING. ASSOC. Off. Seed Anal. Proc. (39) : 23-58.

(7) BORTiiwiCK, H. A.

1925. FACTORS INFLUENCING THE RATE OF GERMINATION IN SEED OF ASparaffUS

oMcinalis, Calif. Agr. Expt. Sta. Tech. Paper 18,17 pp.

(8) BoswELL, V. R., TooLE, E. H., TooLE, V. K,, and FISCHEK, D. F.

1940. A STUDY OF RAPID DETERIORATION OF VEGETABLE SEEDS AND METHODS FOR

ITS PREVENTION. U. S. Dcpt. Agr. Tech. Bui. 708. 48 pp., illus.

(9) BROWN, R.

1940. AN EXPERIMENTAL STUDY OF THE PERMEABILITY TO GASES OF THE SEEDcoAT MEMBRANES OF GucurMta pcpo. Auu. Bot. 4: 379^395.

(10) CANADIAN DEPARTMENT OF AGRICULTURE.

1950. METHODS AND PROCEDURES OF SEED TESTING. Can. Dcpt. Agr., Prod.

Service, Plant Prod. Div. Ottawa. 35 pp.

(11) ClESLAR, A,

1883. UNTERSUCHUNGEN ÜBER DEN EINFLUSS DES LICHTES AUF DIE KEIMUNG

DER SAMEN. FoTSch. Geb. Agr. Phys. 6: 27(>-295.

(12) CLARK, B. E.

1950. HOW MANY PLANTS SHOULD A TRUENESS-TO-TYPE TRIAL CONTAIN?

Assoc. Off. Seed Anal. Proc. (40) : 89-91.

(13) CoLEMAN, D. A., and BOERNER, E. G.

1936. THE BROWN-DUVEL MOISTURE TESTER AND HOW TO OPERATE IT. XT. S.

Dept. of Agr. Dept. Bui. 1375. 44 pages, illus.

(14) CROSIER, W.

1926. PREVALENCE AND SIGNIFICANCE OF FUNGUS ASSOCIATES OF PEA SEEDS.

Assoc. Off. Seed Anal. Proc (28) : 101-107. (Rev. 1927, 1936.)

(15)

1939. INFLUENCE OF CHEMICAL TREATMENTS ON INFECTION OF CRUCIFEROUS

SEEDLINGS BY Alternaría SPP. AND Rhizopus nigricans. Assoc.

Off. Seed Anal. Proc. (31) : 116-120.

(16)

1951. REPORT OF THE COMMITTEE ON THE DETERMINATION OF SEED-BORNE

DISEASES. Internat. Seed Testing Assoc. Proc. 16: 291-298.

(17) DICKSON, J. G.

1947. DISEASES OF FIELD CROPS. McGraw-Hill Book Co., New York. 429 pp.

(18) DOYER, L. C.

1938. MANUAL FOR THE DETERMINATION OF SEED-BORNE DISEASES. 58 pp., iUUS.

H. Veenan and Zonen, Wageningen, Netherlands.

297
298 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

(19) FLEMION, F.

1934. DWARF SEEDLINGS FROM NON-AFTEK-RIPENED EMBRYO'S OF PEACH, APPLE,

AND HAWTHORNE. Contrib. Boyce Thompson Inst. 6: 205-209.

(20)

1938. BREAKING THE DORMANCY OF SEEDS OF Crataegus spp. Contrib. Boyce

Thompson Inst. 9: 409-423.

(21) and OLSON, J.

1950. LYGUS BUGS IN RELATION TO SEED PRODUCTION AND OCCURRENCE OF

EMBRYO^LESS SEEDS IN VARIOUS JJnibelliferous SPECIES. Contrib.

Boyce Thompson Inst. 16: 39-46.

(22) FLINT, L. H.

1934. LIGHT IN RELATION TO DORMANCY AND GERMINATION IN LETTUCE SEED.

Science. 80: 38-40.

(23) GASSNER, G.

1915. ÜBER DIE KEIMUNGS AUSLÖSENDE WIRKUNG DER STICKSOFF-SALZE AUF

LICHTEMPFINDLICHE SAMEN. Jahr. f. WÍSS. Bot. 55 : 259-342.

(24) GKISWOLD, S. M.

1936. THE EFFECT OF ALTERNATE MOISTENING AND DRYING ON GERMINATION

OF WESTERN RANGE PLANTS Bot. Gaz. 98: 243-269.

(25) GROVES, J. W., and SKOLKO, A. J.

1944. NOTES ON SEED-BORNE FUNGI. Can. Jour. Res. 0. 22: 217-234.

(26) HARTER, L. L., and ZAUMEYER, W. J.

1944. A MONOGRAPHIC STUDY OF BEAN DISEASES AND METHODS FOR THEIR

CONTROL. U. S. Dept. Agri. Tech. Bui. 868. 160 pp., illus.

(27) HEIT, C. E.

1948. LABORATORY GERMINATION RESULTS WITH HERB AND DRUG SEED. ASSOC.

Off. Seed AnaL Proc. (38) : 58-62.

(28)

1950. GERMINATION OF SENSITIVE FLOWER SEED KINDS AND VARIETIES WITH

SUGGESTED METHODS FOR TESTING IN THE LABORATORY. AsSOC. Off.

Seed Anal. Proc. (40) : 107-117.

(29) ISELY, D.

1947. SEED CHARACTERS OF ALFALFA AND CEIRTAIN OTHER SPECIES OF Medlcaffo. Iowa State Jour. Sei. 21: 153-159, illus.

(30) KiNZEL, W.

1913-1926. FROST UND LICHT ALS BEEINFLUSSENDE KRÄFTE BEI DER SAMENKEIMUNG. Ulmer ; Stuttgart 1, 2, and 3: 1-170.

(31) KOEHLER, B., and HOLBEBT, J. R.

1930. CORN DISEASES IN ILLINOIS. 111. Agr. Expt. Stat. Bul. 354. 164 pp.

illus.

(32) KOMMEREL, E.

1927. QUANTITATIVE VERSUCHE ÜBER DEN EINFLUSS DES LICHTES VERSCHIEDENER WELLENLÄNGEN AUF DIE KEIMUNG VON SAMEN. Jahr. WÍSS.

Bot. 66: 461-512.

(33) LEENDERTZ, IR. K. -T ... « ^ m 4.

1948. THE DETERMINATION OF MOISTURE IN SEEDS. Internat, öeeü lest.

Assoc. Proc. 14 (1) : 38-46, illus.

(34) I/EGGATT C TV.

1948. GERMINATION OF BORON-DEFICIENT PEAS. Sci. Agr. 28 (3) C 131-139.

(35) MANGELSDORF, P. O.

1926. THE GENETICS AND MORPHOLOGY OF SOME ENDOSPERM CHARACTERS IN

MAIZE. Conn. Agr. Expt. Sta. Bui. 279: 509-614.

(36) MCLEAN, D. M.

1947. Altemaria BLIGHT AND SEED INFECTION, A CAUSE OF LOW GERMINATION

IN CERTAIN RADISH SEED CROPS. Jour. Agr. Res. 75: 71-79.

(37) MORSE, W. J. , „ ,

1947. COWPEAS : CULTURE AND VARIETIES. U. S. Dept. Agr. Farmers Bui.

1148. 18 pp.

(38) et al. „ , ^ ,

1941. SOYBEAN CULTURE AND VARIETIES. U. S. Dept. Agr. Farmers' Bui.

1520. 38 pp.

(39) MUSKETT, A. E.

1948. TECHNIQUE FOR THE EXAMINATION OF SEEDS FOR THE PRESENCE OF

SEED-BORNE FUNGI. British Mycol. Soc. Trans. 30: 74-83.

(40) NEERGAARD, P. ^ , TT .

1945. DANISH SPECIES OF Alternaría AND Stemphylium. Oxford Univ.

Press. London. 560 pp.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 299

(41) RANDOLPH, L. F., and Cox, L. G.

1943. FACTOES INFLUENCING THE GERMINATION OF IRIS SEED AND THE RELATION OF INHIBITING SUBSTANCES TO EMBRYO DORMANCY. Amer. SOC.

Hort. Sei. Proc. 43 : 284-300.

(42) SHUCK, A. L.

1936. THE GERMINATION OF SECONDARY DORMANT TOMATO SEEDS AND THEIR

FORMATION. Internat. Seed Test. Assoe. Proc. 8 (2) : 136-158.

(43) STEBLER, F. G.

1881. UEBER DEN EINFLUSS DES LICHTES AUF DIE KEIMUNG. Vierteljahrsch.

Naturforsch. Ges., Zurich. 26: 102-104.

(44) SWALLEN, J. R., and ROGLER, G. A.

1950. THE STATUS OF CRESTED WHEATGRAss. Agronomy Jour. 42 (11) :

571.

(45) THORNTON, N.

1936. CARBON DIOXIDE STORAGE. IX. GERMINATION OF LETTUCE SEED AT HIGH

TEMPERATURES IN BOTH LIGHT AND DARKNESS. Contrib. BoyCe

Thompson Inst. 8: 25-40.

(46) TooLE, E. H., and TooLE, V. K.

1946. BELATION OF TEMPERATURE AND SEED MOISTURE TO THE VIABHITY OF

STORED SOYBEAN SEED. IT. S. Dept. Agr. Clrc. 753. 9 pp.

(47) UNITED STATES DEPARTMENT OF AGRICULTURE.

1941. AIR-OVEN AND WATER-OVEN METHODS SPECIFIED IN THE OFFICIAL GRAIN

STANDARDS OF THE UNITED STATES FOR DETERMINING THE MOISTURE

CONTENT OF GRAIN. U. S. Dcpt. of Agr. Scrvice and Regulatory

Announcements No. 147. 3 pp.

(48) UNITED STATES DEPARTMENT OF AGRICULTURE.

1950. RULES AND REGULATIONS UNDER THE FEDERAL SEED ACT. U. S. DEPT.

Agr. Service and Regulatory Announcements No. 156. 51 pp.

(49) WALKER, J.

1950. PLANT PATHOLOGY. McGraw-Hill Book Co., New York. 669 pp., illus.
SELECTED REFERENCES

The references listed below have been selected to give a cross section

of the field of seed technology. In preparing the list particular emphasis was placed on publications that are recent, comprehensive, or

of practical significance. Much of the literature in seed technology

appears in the following publications: Association of Official Seed

Analysts Proceedings (1908 to date), News Letter (1927 to date),

Handbook Contributions (various dates) ; International Seed Testing Association Proceedings (1922 to date) ; Contributions of the

Boyce Thompson Institute for Plant Eesearch. Occasional papers

on seed technology are also published in various journals and bulletins in the general field of plant science.

PURITY DETERMINATION

ÂBERG, E., PORTER, R. H., and ROBBINS, W. A.

1945. FURTHER EXPERIMENTS WITPI IOWA AIR BLAST SEED SEPARATOR FOR THE

ANALYSIS OF SMALL-SEEDED GRASSES. lOWa Agi*. Expt. Stü. ReS.

Bul. 340: 767-804.

BASS C. M.

1938 VIABILITY OF INJURED WEED SEEDS. Assoc. Off. Seed Anal. Proc. (30) :

52-57.

and HOOKER, D. * /AíU. C ^ A T

1941. REPORT OF WORK ON WILD ONION BULBLETS. Assoc. Ott. feeed Anal.

Proc. (33) : 42-43.

BROWN, E. O.

1948. SEED STATISTICS FOR GRASSES, LEGUMES, FORBS, AND WOODY PLANTS.

U. S. Dept. Agr. Soil Conserv. Serv. 5 pp.

BRUMMITT, M.

1946 GERMINATION OF DODDER SEED OCCURRING IN LESPEDEZA. ASSOC. Uit.,

Seed Anal. Proc. (36) : 125-131.

CALDWELL, B. A 1 TVT T 4^4. 1941. MOTTLED SEED IN SWP:ETCLOVER. Assoc. Off. Seed Anal. News L.etter.

15: 3-4.

CULL, H., and JUSTICE, O. L.

1950 CLASSIFICATION OF INSECT-INFESTED SEEDS OF LEGUMES, ASSOC. Uli.

Seed Anal. News Letter. 24 (3) : 28-31.

FRISAK, A. , * ^xsa C. ^ A 1

1928 ''STRONGER METHOD" AND "QUICKER METHOD." Assoc. Ott. heed Anal.

News Letter. 1 (6) : 7-9.

GAERTNER, E. E.

1950. STUDIES OF SEED GERMINATION, SEED IDENTIFICATION, AND HOST RELATIONSHIP IN DODDERS, Cuscuta SPP. Cornell Univ. Memoir. 294.

56 pp.

HOEFLE, O. M. ,r . T. ^ C.^ T> 1

1932. WEED SEEDS FOUND IN VEGETABLE SEEDS. N. Y. Agr. Lxpt. feta. Bin.

NO. 616. 15 pp.

HOOKER, D.

1941 REPORT OF SUBCOMMITTEE ON STUDY OF VIABILITY OF INJURED WEED SEEDS.

ASSOC. Ofe. Seed Anal. Proc. (33) : 34-50.

TUSTTCE O L

1951. A UNIFORM CLASSIFICATION OF SOME KINDS OF SEEDS REGARDED AS EITHER

CROPS OR WEEDS. ASSOC. Off. Seed Anal. News Letter. 25 (1) : 5-8.

and WHITEHEAD, M. D.

1942. VIABILITY OF BULBLETS OF AlUum canadense AND Allium vineale OCCURRING IN SEED OF CEREALS AND CRIMSON CLOVER. ASSOC. Off. Seed

Anal. Proc. (34) : 109-114.

300
TESTING AGRICULTURAL AND VEGETABLE SEEDS 301

KANIPE, L. A.

1940. THE PLANT PRODUCING VALUE OF INJURED SEEDS OF BumeW SPP. ASSOC.

On, Seed Anal. Proc. (32) : 32-39.

1942. REPORT OF THE SUBCOMMITTEE (A. O. S. A.) ON METHODS FOR THE ANALYSIS OF SMALL SEEDS. Assoc. Off. Seed AnaL Proc. (34) 32-40.

LEGGATT, C. W.

1938. A NEW SEED BLOWER. Assoc. Off. Seed Anal. Proc. (30) : 120-132.

1941. THE "CLIMAX" BLOWING POINT IN THE TESTING OF GRASS SEEDS FOR PERCENTAGES OF PURE LIVE SEED. Dlv. Bot. and Plant Path. Dept. of

Agr. Ottawa, Canada. Contrib. No. 657. 12 pp.

1942. SOURCES OP VARIATION IN PURITY ANALYSIS. PURITY ANALYSIS SIZE

OF SAMPLE. ACCURACY OF TESTS AND TOLERANCES. AsSOC. Off. Seed

Anal. Oontrib. Handbk. on Seed Test. 13 pp.

MERCER, S. P.

1932. THE VARIETAL PURITY OF COMMERCIAL ITALIAN RYEGRASS. Intomat.

Seed Test. Assoc. Proc. 4: 153-160.

NoRRis, E. L.

1944. REPORT OF THE SUBCOMMITTEE ON RANGE GRASS STUDIES. AsSOC. Off.

Seed Anal. Proc. (35) : 63-67.

PlERPOINT, M.

1947. VIABILITY OF INJURED WEED SEED, LoUum temulentum, DARNEL. Assoc.

Off. Seed Anal. Proc. (37) : 34-37.

PORTER, R. H.

1938. FURTHER EXPERIMENTS WITH MODIFIED TECHNIQUES FOR THE DETERMINATION OF PURITY AND VIABILITY OF BLUEGRASS SEED, Poa pratefbSlS L.

Iowa Agr. Expt. Sta. Res. Bui. 235: 91-111.

1938. UNIFORM TECHNIQUES FOR THE ANALYSIS OF SMALL-SEEDED GRASSES.

Assoc. Off. Seed Anal. Proc. (30) : 133-171.

1949. RECENT DEVELOPMENTS IN SEED TECHNOLOGY. Bot. RCV. 15: 242-245.

— and Koos, K.

1936. GERMINATION OF INJURED WEED AND CROP SEEDS. Assoc. Off. Seed Anal.

Proc. (28) : 68-73.

— and LEGGATT, C. W.

1942. A NEW CONCEPT OF PURE SEED AS APPLIED TO SEED TECHNOLOGY. Sei.

Agr. 23: 80-103.

SEIFERLE, N. K., and PORTER, R. H.

1937. A POSSIBLE MODIFICATION IN PURITY ANALYSIS OF ORCHARD GRASS. ASSOC.

Off. Seed Anal. Proc. (29) : 94-96.

SIRRINE, E. F., and ANDERSON, A. W.

1940. TECHNIQUE OF PURITY ANALYSIS. ASSOC. Off. Seed Anal. Contrib. to

Handbk. Seed Test. 6 pp.

SJELBY, K., and STAHL, C.

1944. HOW ARE THE DIFFERENT SEED SPECIES CLASSIFIED IN THE PURITY ANALYSIS BY SEED TESTING STATIONS ALL OVER THE WORLD? Internat. Seed

Test. Assoc. Proc. 13: 128-146.

STAHLER, L. M.

1935. PRELIMINARY WORK ON GERMINATION OF AgTOpyrOfl CARYOPSIS. AsSOC.

Off. Seed Anal. Proc (27) : 56-59.

STEVENS, O. A.

1919. WEED SEEDS IN ANALYSIS. Seed World. 5: 243.

ToRPY, F. J., SIRRINE, E. F., and TOOLE, E. H.

1937. SOME COMPARATIVE STUDIES ON BLOWING METHODS OF Poa prateusis.

Assoc. Off. Seed Anal. Proc. (29) : 97-102.

WRIGHT, W. H.

1936. HULLED SEEDS OF Amhrosia artemisiifolia (L.) AîïD Agropyron repens

(L.) BEAUV. Assoc. Off. Sccd Anal. News Letter. 10 (1) : 5-6.

957116—52——21 ; ;:
302 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

PHYSIOLOGY AND GERMINATION

ANDERSEN, A. M.

1932. THE EFFECT OF REMOVING THE GLUMES ON THE GERMINATION OF SEEDS OF

Poa compressa. Amer. Jour. Bot. 19: 835 supp.

1935. THE EFFECT OF SOIL AND LIGHT IN RELATION TO NITRATE SOLUTION ON

THE GERMINATION OF SEED OF Poa compressa L. Amer. Jour. Bot.

22: 906 supp.

1939. MOISTENING AND DRYING AS A PRETREATMENT IN GERMINATING SEEDS OF

Poa compressa. Assoc. Off. Seed AnaL Proc. (30): 246.

1940. GERMINATION OF SEED OF Paspalum fiotatum FLÜGGE. Amer. Jour.

Bot. 27: 12 supp.

1941. THE EFFECT OF DIFFERENT TEMPERATURES ON THE GERMINATION OF

FRESHLY HARVESTED AND MATURE SEED OF ACCOflOpUS COmprCSSUS.

Assoc. Off. Seed Anal. Proc. (33) : 99-102.

1941. GERMINATION OF FRESHLY HARVESTED SEED OF KENTUCKY BLUEGRASS.

Assoc. Ofe. Seed Anal. Proc. (33) : 96-98.

1946. THE EFFECT OF LIGHT, TEMPERATURE, AND POTASSIUM NITRATE ON THE

GERMINATION OF AgrOSUs tCnUlS SIBTH. AND A. teUUiS VAR. HIGHLAND SEED. Assoc. Off. Seed Anal. Proc. (36) : 112-125.

1947. SOME FACTORS INFLUENCING THE GERMINATION OF SEED OF Poa COmprCSSa

L. Assoc. Off. Seed Anal. Proc. (37) : 134-143.

1947. THE EFFECT OF ALTERNATING TEMPERATURES, LIGHT INTENSITIES, AND

MOISTENING AGENTS OF THE SUBSTRATUM ON THE GERMINATION OF

FRESHLY HARVESTED SEED OF OREGON GROWN RYEGRASS {LoUum Spp.).

Assoc. Off. Seed Anal. Proc. (37) : 152-161.

1948. SOME FACTORS ASSOCIATED M^ITH THE BROWNING OF SUGAR BEET (Beta

vulgaris L.) SEEDLINGS IN LABORATORY GERMINATION TESTS. ASSOC.

Off. Seed Anal. Proc. (38) : 52-58.

1949. THE EFFECT OF TEMPERATURE ON THE SPEED OF GERMINATION OF SPINACH

(Spinacia olerácea L.) SEED. ASSOC. Off. Seed Anal. Proc. (39) :

79-82.

1950. THE SWOLLEN SEED PROBLEM IN SUCKLING CLOVER, TrifoUum duMum

SIBTH. Assoc. Off. Seed Anal. Proc. (40) : 77-82.

1951. THE INTERPRETATION OF NORMAL AND ABNORMAL SEEDLINGS IN SOME

CEREALS. Internat. Seed Test. Assoc. Ptoc. 16. 197-213.

and DRAKE, V. C.

1944. PRELIMINARY STUDY OF SEED OF CRESTED WHEATGRASS, Agropyron cristatum L. EXHIBITING DELAYED GERMINATION. Assoc. Off. Seed Anal.

Proc. (35) : 146-153.

-and JUSTICE, O. L.

1948. GERMINATION OF SEEDS OF FIVE KINDS OF CUCURBITS AT TWO TEMPERATURES. Assoc. Off. Seed Anal. Proc. (38) : 45-47.

ARNDT, C. H.

1945 TEMPERATURE-GROWTH RELATIONS OF THE ROOTS AND HYPOCOTYLS OF COTTON SEEDLINGS. Plant Physiol. 20 (2) : 200-220.

1946. THE INTERNAL INFECTTíON OF COTTON SEED AND THE LOSS OF VIABILITY.

Phytopath. 36: 30-37.

BAKER, K. F. ^ ^

1948. THE COAT BOUND CONDITION OF GERMINATING PEPPER SEEDS. Amer. Jour.

Bot. 35: 192-193.

BARRONS, K. C, and MCLEAN, D. M.

1945 A STUDY OF THE CAUSES OF LOW GERMINATION OF RADISH SEED CROPS.

Mich. Agr. Expt. Sta. Quar. Bui. 27: 39&-408.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 303

BARTON, L. V.

1944. SOME SEEDS SHOWING SPECIAL DORMANCY. Contrib. Boyce Thompson

Inst. 13: 259-271.

1949. SEED PACKETS AND ONION SEED VIABILITY. Contrib. Boyce Thompson

Inst. 15: 341-352.

BASS, C. M.

1928. METHODS OF GERMINATING NEW ZEALAND SPINACH SEED. ASSOC. OFF. SEED

AnaL Proe. (19-20) : 36-37.

1948. GERMINATION OF FRESHLY HARVESTED OATS. AsSOC. Off. Seed Anal.

Proc. (38) : 47-52.

BORTHWICK, H. A.

1931. CARROT SEED GERMINATION. Amer. Soc. Hort. Sei. Proc. 28: 310-315.

and BAINER, R.

1934. THRESHER AND OTHER MECHANICAL INJURY TO SEED BEANS OF THE LIMA

TYPE. Calif. Agr. Expt. Sta. Bui. 580. 30 pp.

BROWN, E., and TOOLE, E. H.

1939. EVALUATION OF SEEDLINGS. Internat. Seed Test. Assoc. Proc. 11 (2) :

89-95.

TOOLE, E. H., and Goss, W. L.

1934. MOISTURE CONTENT AN IMPORTANT FACTOR IN INTERNATIONAL TRADE IN

SEEDS. Internat. Seed Test. Assoc. Proc. 6: 405-409.

BURTON, G. W.

1940. FACTORS INFLUENCING THE GERMINATION OF SEED OF TrifoUum repens.

Jour. Amer. Soc. Agron. 32: 731-738.

CLARK, B. E.

1943. COMPARATIVE LABORATORY AND FIELD GERMINATION OF ONION SEED. ASSOC.

Off. Seed Anal. Proc (34) : 90-99.

1948. NATURE AND CAUSES OF ABN0RMATJ:TIES IN ONION SEED GERMINATION.

Cornell Univ. Agr. Expt. Sta. Memoir. 282. 27 pp.

COCHRAN, H. L.

1935. SOME FACTORS WHICH INFLUENCE THE GERMINATION OF PEPPER SEEDS.

Amer. Soc Hort. Sei. Proc 32: 477-480.

Cox, L. G., MuNGER, H. M,, and SMITH, E. A.

1945. A GERMINATION INHIBITOR IN THE SEED COATS OF CERTAIN VARIETIES OF

CABBAGE. Plant Physiol. 20: 289-294.

CROCKER, W.

1916. THE MECHANICS OF DORMANCY IN SEEDS. Amer. JouT. Bot. 3: 99-120.

1936. EFFECT OF THE VISIBLE SPECTRUM UPON THE GERMINATION OF SEEDS AND

FRUITS. BIOLOGICAL EFFECTS OF RADIATION. 2: 791-827. McGraW

Hill Book Co., New York.

1948. GROWTH OF PLANTS. TWENTY YEARS RESEARCH AT BOYCE THOMPSON INSTITUTE. 459 pp. Reinhold Pub. Corporation, New York.

CROSIER, W. L.

1943. BALDHEADS IN BEANS, OCCURRENCE AND INFLUENCE ON YIELD. ASSOC.

Off. Seed Anal. Proc (34) : 118-123.

1950. GERMINATION OF SEEDS OF BROAD BEAN, Vicia foba, Assoc Off. Seed

Anal. News Letter. 24 (1) : 5.

• and PATRICK, S. R.

1939. INJURIES TO SEEDLINGS INDUCED BY CHEMICALS DISSOLVING FROM GERMINATOR TRAYS. Assoc Off. Seed Anal. Proc (30) : 253-254.

CROSIER, W. F., PATRICK, S. R., and WILLITTS, C. O.

1937. ZINC INJURY IN GERMINATION TEST. Internat. Seed Test. Assoc Proc

9: 257-267.

CULLINAN, B.

1941. GERMINATING SEEDS OF SOUTHERN GRASSES. AsSOC Off. Seed Anal.

Proc (33) : 74-76.

1947. GERMINATING CERTAIN SOUTHERN GRASS SEEDS. AsSOC Off. Sood Anal.

Proc (37) : 162-163.
304 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

CUNDIFF, C. B.

1946. PROBLEMS OF SOYBEAN GERMINATION. Assoc. Off. Seed AnaL Proc.

(36) : 132-134.

CURTIS, O. F., and CLARK, D. G.

1950. AN INTRODUCTION TO PLANT PHYSIOLOGY. McGraw-Hill Book Co., Inc.

New York. 722 pp. illus.

DAVIS, G. N.

1938. GERMINATION OF CUCURBIT SEED IN SAND. ASSOC. Off. Seed Anal. Proc.

(29) : 133-135.

DECKER, A. E., and REITZ, L. P.

1947. GERMINATION TESTS WITH FLAX STORED AT DIFFERENT MOISTURE AND

TEMPERATURE LEVELS. Assoc. Off. Seed Anal. Proc. (37) : 115-120.

DILLMAN, A. C, and TOOLE, E. H.

1937. EFFECT OF AGE, CONDITION, AND TEMPERATURE ON THE GERMINATION OF

FLAX SEED. JouT. Anier. Soc. Agron. 29: 23-29.

DRAKE, V. C.

1946. GERMINATION OF SEED OF HARDING GRASS, Phalaris tuderosa VAR.

stenoptera. Assoc. Off. Seed Anal. News Letter. 20 (1) : 7-8.

1946. COMPARISON OF YIELD IN SNAP BEANS BETWEEN NORMAL AND CERTAIN

TYPES OF ABNORMAL PLANTS. ASSOC. Off. Seed Anal. Proc. (36) :

164r-172.

1947. EFFECT OF TEMPi^RATURE AND AGING ON THE GERMINATION OF ALYCE

CLOVER (Alysicarpus vaginalis (L) D. C). ASSOC. Off. Seed Anal.

Proc. (37) : 143-152.

1949. GERMINATION OF RESCUE GRASS SEED AS AFFECTED BY TEMPERATURE, SUBSTRATA, LIGHT, AND REMOVAL OF GLUMES. Assoc. Off. Seed Anal.

News Letter. 23 (2) : 42-45.

and ATWATER, B.

1939. OBSERVATIONS ON LIMA BEAN GERMINATION. Assoc. Off. Seed Anal.

Proc. (30) : 218-220.

DUVEL, J. W. T.

1904. THE VITALITY AND GERMINATION OF SEEDS. U. S. Dept. AgT. BuT. Plant

Indus. Bill. No. 58. 24 pp.

ECKERSON, S.

1913. A PHYSIOLOGICAL AND CHEMICAL STUDY OF AFTER-RIPENING. Bot. GaZ.

55: 286-299.

EVENARI, M.

1949. GERMINATION INHIBITORS. Bot. Rev. 15 (3) : 353-195.

EWART, A. J.

1908. ON THE LONGEVITY OF SEEDS. Proc. Roy. Soc. Vlctoiia. 21: 1-210.

FISKE, G.

1939. ABNORMALITIES IN THE GERMINATION OF LIMA BEANS. ASSOC. Off. Seed

Anal. Proc. (30) : 214-217.

FLEMION, F.

1938. A RAPID METHOD FOR DETERMINING THE VIABILITY OF DORMANT SEEDS.

Contrib. Boyce Thompson Inst. 9: 339-351.

and WATERBURY, E.

1941. EMBRYO-LESS DILL SEEDS. Contrib. Boyce Thompson Inst. 12: 157-161.

and WATERBURY, E.

1941. FURTHER STUDIES ON RAPID DETERMINATION OF THE GERMINATIVE CAPACITY OF SEEDS. Contrib. Boyce Thompson Inst. 11: 455-464.

and PooLE, H.

1948. SEED VIABILITY TESTS WITH 2, 3, 5-TRlPHENYL-TETRAZOLlUM-CHLORlDE.

Contrib. Boyce Thompson Inst. 15 : 243-258.

- and UHLMANN, G.

1946. FURTHER STUDIES OF EMBRYOLESS SEEDS IN THE UMBELLIFEREAE. Contrib. Boyce Thompson Inst. 14 (4) : 283-293.

FLINT, L. H. and MCALISTER, E. D.

1935. WAVE LENGTHS OF RADIATION IN THE VISIBLE SPECTRUM INHIBITING THE

GERMINATION OF LIGHT-SENSITIVE LETTUCE SEED. Smithsonian Misc.

Coll. 94 (4) : 1-11.

FORBES, I., and FERGUSON, M. H.

1948. EFFECTS OF STRAIN DIFFERENCES, SEED TREATMENT, AND PLANTING DEPTH

ON SEED GERMINATION OF Zoysla spp. Jour. Amer. Soc. Agron.

40 (8) : 725-732.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 305

FORSYTH, D., and VOGEL, D. A.

1945. EFFECT OF SEEDCOAT INJURIES DURING THRESHING ON EMERGENCE OF

FLAX SEEDLINGS. Jour. Amer. Soc. Agr. 37: 387-393.

FORWARD, B. F.

1949. STUDIES OF GERMINATION IN OATS. (ABSTRACT.) Assoc. Off. Seed AnaL

Proc. (39) : 83-84.

FREDERIKSEN, P. S.

1949. GERMINATION OF FIBRE FLAX SEED INJURED BY THKESHING. Internat.

Seed Test. Assoe. Proc. 14 (2) : 144-169.

FUELLEMAN, R. F., and BURLISON, W. L.

1942. GERMINATION STUDIES OF BROMEGRASS SEED, Bromus inermis LEYSS. III.

State Acad. Sei. Trans. 35 (2) : 32-34.

GARMAN, R., and BARTON, L. V.

1946. RESPONSE OF LETTUCE SEED TO THIOUREA TREATMENT AS AFFECTED BY

VARIETY AND AGE. Contrib. Boyco Thompson Inst. 14: 229-241.

GRIFFITHS, A. E.

1938. OBSERVATIONS ON THE GERMINATION OF LETTUCE SEED. Contrib. BoyCO

Thompson Inst. 9: 329-337.

HANLEY, F., and WOODMAN, R. M.

1930. THE EFFECT OF SULFURIC ACID TREATMENT ON THE GERMINATION OF

SUGAR BEET SEED. Jour. Soc. Ohcm. Indus. Trans, and Commun.

49: 215T-220T.

HARRINGTON, G. T.

1916. AGRICULTURAL VALUE OF IMPERMEABLE SEEDS. JOUT. AGR. RES. 6: 761-

796.

1923. FORCING THE GERMINATION OF FRESHLY HARVESTED WHEAT AND OTHER

CEREALS. Jour. Agr. Res. 23: 79-100.

1923. USE OF ALTERNATING TEMPERATURES IN THE GERMINATION OF SEEDS.

Jour. Agr. Res. 23: 295-332.

HARTER, L. L.

1930. THRESHER INJURY A CAUSE OF BALDHEAD IN BEANS. JoUr. Agr. ReS.

40: 371-384. Illus.

HAY, W. D.

1936. FURTHER STUDIES WITH THE GERMINATION OF CRESTED WHEATGRASS.

Assoc. Off. Seed Anal. Proc. (28) : 86-88.

1949. PROBLEMS IN TESTING COATED AND PELLETED SEEDS. PANEL DISCUSSION.

Assoc Off. Seed Anal. Proc. (39) : 72-73.

HEIT, C. E.

1946. RECENT FINDINGS ON LABORATORY GERMINATION AND LONGEVITY OF NEW

ZEALAND SPINACH SEED. Assoc. Off. Seed Anal. Proc. (36) : 115-120.

1948. REPORT OF THE SUBCOMMITTEE ON DORMANCY IN SEEDS. AsSOC. Off.

Seed Anal. Proc. (38) : 25-26.

and MuNN, M. T.

1941. NEW ZEALAND SPINACH GERMINATION STUDIES. AsSOC. Off. Seed Anal.

Proc. (33) : 90-95.

and MUNN, M. T.

1947. EFFECT OF LOW SEED VITALITY ON YIELD. Farm Rcs. (Ncw York) 13

(2) : 14-15.

HEWITT, E. J.

1945. ''MARSH SPOT" IN BEANS. Nature. 155 (3923) : 22-23.

HiGGINS, B. B.

1949. SOME FACTORS AFFECTING VIABILITY OF PEANUT SEED. (ABSTRACT.)

Phytopath. 39 (1-6) : 496.

HILLS, K. L.

1944. DORMANCY AND HARDSEEDEDNESs IN TrifoUum suhterrafieum. Austral.

Sei. and Indus. Res. Jour. 17: 186-196.

HODGSON, H. J.

1949. EFFECT OF HEAT AND ACID SCARIFICATION ON GERMINATION OF SEED OF

BAHIA GRASS, Paspalum notatum FLtJGGE. Jour. Amer. Soc. Agron.

41 (11) : 531-533.

HOPKINS, E. F.

1924. STUDIES ON LETTUCE SEED GERMINATION. Assoc. Off. Seed Anal. Proc.

(16): 68-69.
306 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

HULL, F. H.

1937. INHEEITANCE OF REST PERIOD OF SEEDS AND CERTAIN OTHER CHARACTERS

IN THE PEANUT. Fla. Agr. Expt. Sta. Tech. BuL 314. 46 pp.

HYDE, E. O. C.

1949. METHODS FOR DETERMINING THE VIABILITY OF VARIOUS SEEDS BY TETRAzoLiuM STAINING. I. cHEWiNGs FESCUE. New Zeal. Sci. and Tech.

Jour. Sect. A. Agr. Res. 31 (1) : 13-20.

INGALLS, R. A.

1946. A STUDY OF THE; OCCURRENCE OF BALDHEADS IN BEANS AND A COMPARISON

OF THEIR FIELD PERFORMANCE WITH THAT OF NORMAL PLANTS. ASSOC.

Ofe. Seed AnaL Proc. (36) : 177-183.

ISELY, D.

1951. THE COLD TEST FOR CORN. Internat. Seed Test. Assoc. Proc. 16: 299-311.

JONES, J. P.

1928. A PHYSIOLOGICAL STUDY OF DORMANCY IN VETOH SEED. Cornell Univ.

Expt. sta. Memoir No. 120. 50 pp.

JUSTICE, O. L.

1947. OBSERVATIONS ON THE GERMINATION OF NEW ZEALAND SPINACH SEED.

Assoc. Off. Seed Anal. Proc. (37) : 120-126.

and ANDERSEN, A. M.

1946. GERMINATION OF KENTUCKY BLUEGRASS SEED AT TWO SETS OP ALTERNATING

TEMPERATURES. Assoc. Off. Seed Anal. News Letter. 20 (1) :

10-12.

and WHITEHEAD, M. D.

1942. VIABILITY OF VELVETBEAN, BUzolo'bium SPP., SEED AS AFFECTED BY DATE

OF HARVEST, WEATHERING, STORAGE, AND LODGING. Jour. Amer. Soc.

Agron. 34 (11) : 1000-1009.

1946. SEED PRODUCTION, VIABILITY, AND DORMANCY IN THE NUTGRASSES CypeVUS

rotundus AND G. esculentus. Jour. Agr. Res. 73: 303-318.

KocK, P. C, and HUNTER, R. F.

1950. A GERMINATION INHIBITOR FROM SUGAR BEET. Nature. 166: 440-441.

LAKON, G.

1949. THE TOPOGRAPHICAL TETRAZOLIUM METHOD FOR DETERMINING THE GERMINATING CAPACITY OF SEEDS. Plant Physiol. 24: 389-394.

LEBEDEFF, G. A.

1947. STUDIES ON THE INHERITANCE OP HARD SEEDS IN BEANS. Jour. Agr. Res.

74: 205-215.

LEGGATT, C. W.

1946. GERMINATION OP SEEDS OF THREE SPECIES OF Agrostis. Can. Jour. Res.

Sect. C. 24 (1) : 7-21.

1948. A CONTRIBUTION TO THE STUDY OF DORMANCY IN SEEDS OF Lactuca

sativa. Can. Jour. Res. Sect. C. 26: 194-217.

LEWIS, N. G.

1942. DORMANCY IN CULTIVATED MUSTARD AND THE USE OF POTASSIUM NITRATE,

REFEREE REPORT REGION NO. 1. ASSOC. Off. Seed Anal. Proc. (34) :

17-18.

LiGON, L. L., and Cox, J. B.

1950. THE INFLUENCE OF SEVERAL FACTORS ON THE SPROUTING QUALITY OP

OKLAHOMA-GROWN MUNG BEANS, PhaSCOlUS aUTCUS ROXB. Okla. Agr.

Expt. sta. (Ms. Rept. No. 5. 2 pp.)

MAIER, W.

1932. UNTERSUCHUNGEN ZUR FRAGE DER LICHTWIRKUNG AUF DIE KEIMUNG

EINIGER poA- ARTEN. Jahr. Wlss. Bot. 77: 321-392.

MATHEWS, A.C.

1947. OBSERVATION ON METHODS OF INCREASING THE GERMINATION OF Panicum

anceps NICHX. AND Paspalum notatum FLüGGE. Jour. Amer. Soc.

Agron. 39: 439-442.

McSwAiN, E.

1949. SUGGESTED METHODS FOR GERMINATION OF CERTAIN RANGE GRASS SEEDS.

Assoc. Off. Seed Anal. News Letter. 23 (3) : 11.

MEADLEY, G. R. W.

1947. SOME UNUSUAL FEATURES OF SEED GERMINATION WITH PARTICULAR REFERENCE TO suRTERRANEAN OT^ovER. Austr. Inst. Agr. ^cî. Jour. 13:

153-160.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 307

MILLER, E. C.

1910. A PHYSIOLOGICAL STUDY OF THE GERMINATION OF HeUanthUS antlUUS.

Ann. Bot. 24: 693-726.

MUNN, H., and STACKER, E. V.

1942. TOXICITY TO SEEDLINGS OF ZINC FROM GERMINATOR TRAYS. ASSOC, Off.

Seed AnaL Proc. (34) : 82-88.

MuNN, M. T.

1928. THE BEHAVIOR DURING GERMINATION OP CRACKED AND BROKEN SEEDS

FROM BADLY THRESHED RED CLOVER SEED. ASSOC. Off. Seed Anal. PrOC.

(19-20) : 68-69.

1949. ENDIVE SEED GERMINATION. Assoc. Off. Seed AnaL Proc. (39) : 122-125.

1950. A METHOD FOR TESTING THE GERMINABILITY OF LARGE SEEDS. N. Y State

Agr. Expt. Sta. BuL 740. 10 pp.

" and HEIT, G. E.

1941. EMBRYOLESS SEEDS OF THE UMBELLIFERAE. Assoc. Off. Seed Anal. News

Letter. 15 (4) : 10.

NELSON, A.

1927. THE GERMINATION OF Poa SPP. Ann. App. BioL 14: 157-174.

NUTILE, G. E.

1943. ONION SEEDLINGS DEVOID OF ROOT HAIRS. Assoc. Off. Seed AnaL Proc.

(34) : 99-103.

1944. STUDIES ON THE GERMINATION OF LETTUCE SEED INDUCING DORMANCY

WITH couMARiN. Assoc. Off. Seed Anal. Proc. (35) : 120-135.

1946. GROWTH AND YIELD OF BALDHEAD BEAN PLANTS IN THE FIELD PrOC

Assoc. Off. Seed Anal. (36) : 184-188.

1947. EFFECT OP RELATIVE HUMIDITY ON HARD SEEDS IN GARDEN BEANS. AsSOC

Off. Seed Anal. Proc. (37) : 106-114.

and CANPIELD, A. P.

1950. EFFECT OF TEMPERATURE AND LIGHT ON THE GERMINATION OF CELERY SEED

Assoc. Off. Seed Anal. News Letter. 24 (2) : 20-21.

PATRICK, S. R.

1946. IT IS NECESSARY TO PRE-SOAK GARDEN BEET SEED. Assoc. Off Seed Anal

Proc (36) : 150-151.

PETERSEN, D. K.

1934. GERMINATION IN LABORATORY AND SOIL OF FRESH SWOLLEN SEEDS AND

THEIR EVALUATION. Internat. Seed Test Assoc. Proc. 6 (2) ; 331-

ÖÖO.

PHILLIS, E., and MASON, T. G.

1945. THE EFFECT OF EXTREME DESSICATION ON THE VIABILITY OF COTTONSEED

Ann. Bot. (London) (n. s.) 9: 353-359.

PLADECK, M. M.

1940. THE TESTING OF BUFFALO GRASS '^SEED," BucJlloë daCtyloideS ENGELM

Jour. Amer. Soc. Agron. 32 (7) : 486-494.

PLUMMER, A. P.

1943. THE GERMINATION AND EARLY SEEDLING DEVELOPMENT OF TWELVE RANGE

GRASSES. Jour. Amer. Soc. Agron. 65 (1) : 19-34, illus

POPE, M.

1945. SEMINAL ROOT NUMBER IN CULTIVATED BARLEY. Jour. Amcr SoC Asron.

37 C9) : 771-778. • s ^^

PORTER, R. H., DURRELL, M., and ROMM, H. J.

1947. THE USE OF 2, 3, 5- TBIPHENYL-TETRAZOLIUM-CHLORIDE AS A MEASURE OF

SEED GERMINABILITY. Plant Physlol. 22: 149-158

RAY, C. B., and STEWART, R. T.

1937. GERMINATION OF SEEDS FROM CERTAIN SPECIES OF PaSpolUm. Jour AmCr

Soc. Agron. 29 : 548-554.

ROBERTSON, D. W., and LUTE, A. M.

1933. GERMINATION OF FARM CROPS IN COLORADO AFTER STORAGE FOR VARIOUS

PERIODS OF YEARS. Jour. Agr. Res. 46: 455-462.
308 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

SHUCK, A. L.

1934. SOME FACTORS INFLUENCING THE GERMINATION OF LETTUCE SEEDS IN SEED

LABORATORY PRACTICE. N. Y. Agr. Expt. Sta. Tech. Bui. 222. 21 pp.,

illus.

1935. THE FORMATION OF A GROWTH INHIBITING SUBSTANCE IN GERMINATING

LETTUCE SEEDS. Internat. Seed Test. Assoc. Proc. 7 (1) : 9-14.

1935. LIGHT AS A FACTOR INFLUENCING THE DORMANCY OF LETTUCE SEEDS. Plant

Physiol. 10: 193-196.

1936. A PRELIMINARY REPORT ON THE GERMINATION OF MUSTARD SEED. AsSOC.

Off. Seed Anal. Proc. (28) : 74-76.

SMITH, L.

1948. THE EFFECT OF CHAFF OF CEREALS ON GERMINATION OF SEEDS AND ON THE

GROWTH OF MOLD. Jour. Amer. Soc. Agron. 19 (1) : 32-44.

SPRAGUE, V. G.

1940. GERMINATION OF FRESHLY HARVESTED SEEDS OF SEVERAL Poa SPECIES AND

OF Dactylis glomerata. Jour. Amer. Soc. Agron. 32 (9) : 715-721.

STAHL, C.

1936. THE IMPORTANCE OF THE GERMINATING SPEED IN THE CASE OF CRUCIFEROUS

SEEDS. Internat. Seed Test. Assoc. Proc. 8 (1) : 46-53.

STEVENS, O. A.

1935. GERMINATION STUDIES ON AGED AND INJURED SEEDS. Jour. Agr. ReS. 51

(12) : 1093-1106.

STILES, I. E.

1948. RELATION OF WATER TO THE GERMINATION OF CORN AND COTTON SEED.

Plant Physiol. 23: 201-222.

STOUT, M., and TOLMAN, B.

1941. INTERFERENCE OF AMMONIA RELEASED FROM SUGAR BEET BALLS WITH

LABORATORY GERMINATION TESTS. Jour. Amcr. Soc. Agrou. 33 : 65-69.

1941. FACTORS AFFECTING THE GERMINATION OF SUGAR BEET AND OTHER SEEDS

WITH SPECIAL REFERENCE TO THE TOXIC EFFECTS OF AMMONIA. JOUr.

Amer. Soc Agron. 63: 687-713.

TAYLOR, C. A. .

1949. SOME FACTORS AFFECTING GERMINATION OF CELERY SEED. Plant PuySlOl.

24; 93-102.

THOMPSON, R. <j.

1938 DORMANCY IN LETTUCE SEED AND SOME FACTORS INFLUENCING ITS GERMINATION. U. S. Dept. Agr. Tech. Bui. No. 655. 20 pp.

1946. GERMINATION OF ENDIVE SEED AT HIGH TEMPERATURE STIMULATED BY

THIOUREA AND BY WATER TREATMENTS. Amcr. SOC. Hort. Sci. PrOC.

47: 323-326.

THORNTON, N. C.

1945. IMPORTANCE OF OXYGEN SUPPLY IN SECONDARY DORMANCY AND ITS RELATION TO THE INHIBITING MECHANISM REGULATING DORMANCY. Contrib.

Boyce Thompson Inst. 13: 487-500.

TOLMAN, B., and STOUT, M.

1944. SHEARED SUGAR BEET SEED WITH SPECIAL REFERENCE TO NORMAL AND

ABNORMAL GERMINATION. Jour. Amer. Soc. Agron. 36: 749-759.

TooLE, E. H. T ^ ^ a 1

1936. PHYSIOLOGICAL PROBLEMS INVOLVED IN SEED DORMANCY. Internat, feecd

Test. Assoc. Proc. 8 (1) ; 33-41.

1939 OBSERVATIONS ON THE GERMINATION OF FRESHLY-HARVESTED TIMOTHY

SEED. Internat. Seed Test. Assoc. Proc. 11 (2) : 119^139.

1951. RELATION OF SEED PROCESSING AND CONDITIONS DURING STORAGE ON SEED

GERMINATION. Internat. Seed Test. Assoc. Proc 16: 214-225.

— and BROWN, E.

1939. EVALUATION OF SEEDLINGS. Internat. Seed Test. Assoc. Proc 11 (2) :

89-95.

and DiLLMAN, A. C.

1937. EFFECT OF AGE, CONDITION, AND TEMPERATURE ON THE GEÍRMINATION OF

FLAX SEED. Jour. Amcr. Soc Agron. 29: 23-29.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 309

TooLE, E. H., and DRUMMOND, P. L.

1924. THE GERMINATION OF COTTONSEED. Jour. Agv. Res. 28: 285-292.

and Goss, W. L.

1935. MOISTURE CONTENT IMPORTANT FACTOR IN INTERNATIONAL TRADE IN

SEEDS. Internat. Seed Test. Assoc. Proc. 6 (2) : 405-409.

and HoLLowELL, E. A.

1939. EFFECT OF DIFFERENT TEMPERATURES ON THE GERMINATION OF SEVERAL

WINTER ANNUAL SPECIES OF THfoUum, Jour. Amer. Soc. Agron.

31: 604-619.

and TooLE, V. K.

1938. TEMPERATURE AND OTHER FACTORS AFFECTING THE GERMINATION OF THE

SEED OF FESCUES. Internat. Seed Test. Assoc. Proc. 10 (1) : 337-341.

Also in U. S. Dept. Agr. Tech. BuL No. 638. 36 pp. 1939.

1939. GERMINATION OF CARPET GRASS SEED. Jour. Amer. Soc. Agron. 31:

566-567.

1939. GERMINATION OF SOME BraSSiCyŒ TYPES AT DIFFERENT TEMPERATURES.

Internat. Seed Test. Assoc. Proc. 11 (1) : 51-56.

1946. RELATION OF TEMPERATURE AND SEED MOISTURE TO THE VIABILITY OF

STORED SOYBEAN SEED. U. S. Dcpt. Agr. Cîrc. 753. 9 pp.

- WESTER, R. E., and TOOLE, V. K.

1941. THE EFFECT OF FRUIT ROT OF EGGPLANT ON SEED GERMINATION. Amcr

SOC. Hort. Sei. Proc. 38: 496-498.

TOOLE, V. K.

1939. GERMINATION REQUIREMENTS OF THE SEED OF SOME INTRODUCED AND

NATIVE RANGE GRASSES. Assoc. Off. Seed Anal. Proc. (30) : 227-243.

1941. FACTORS AFFECTING THE GERMINATION OF VARIOUS DROPSEED GRASSES

(Sporoholus spp.). Jour. Agr. Res. 62: 691-715.

and DRAKE, V. C.

1939. NOTES ON THE VIABILITY OF THE IMPERMEABLE SEED OF OKRA. AsSOC. Off

Seed Anal. News Letter. 13 (6) : 1-2.

- MILES, E. F., and TOOLE, E. H.

1947. SOIL MOISTURE IN RELATION TO BEET SEED GERMINATION. AsSOC Off Sccd

Anal. Proc. (37) : 127-133.

TOWERS, B.

1938. DORMANCY IN FRESHLY HARVESTED SALSIFY SEED. AsSOC. Off. Seed Anal

Proc. (26) : 286-287.

TUKEY, H. B.

1944. THE EXCISED-EMBRYO METHOD OF TESTING THE GERMINABILITY OF FRUIT

SEED WITH PARTICULAR REFERENCE TO PEACH SEED. AmCr. SoC Hort

Sei. Proc 45: 211-219.

WAGGONER, H. A.

1917. THE VIABILITY OF RADISH SEED AS AFFECTED BY HIGH TEMPERATURES AND

WATER CONTENT. Amcr. Jour. Bot. 4: 299-313.

WALKER, J.

1938. VIABILITY OF FRESHLY HARVESTED CELERY SEED. Amcr. SoC Hort Sci

Proc. 36: 687-690.

WATTS, V. M.

1939. REST PERIOD IN CUCUMBER SEEDS. Amcr. Soc. Hort. Sei. Proc 36-

652-654.

WHARTON, M. F., and FRAZIER, W. A.

1939. EFFECT OF CERTAIN STORAGE TREATMENTS ON FIELD AND LABORATORY GERMINATION OF SEEDS OF IMPERIAL 152 AND IMPERIAL 615 LETTUCE.

Amer. Soc. Hort. Sei. Proc. 36: 680-686.

WHITCOMB, W. O.

1931. HARD SEEDS IN LEGUMES. Mont. Agr. Expt. Sta. Bill. No. 248 63 pp

illus. *

WITTE, H,

1931. SOME INVESTIGATIONS ON THE GERMINATION OF HARD SEEDS OF RED CLOVER,

ALSIKE CLOVER, AND SOME OTHER LEGUMINOUS PLANTS. Internat'

Seed Test. Assoc. Proc 3 (18) : 134-147.

1943. SOME INTERNATIONAL INVESTIGATIONS REGARDING THE GERMINATION OF

^o'^^rri'n^J^^ ^^^^^ ^^ ®^"^- lï^ternat. Seed Test. Assoc. Proc. lö : 77—91.
310 AGRICULTURE HANDBOOK NO, 30, U. S. DEPT. OF AGRICULTURE

WOODFORDE, A. H. A ^ /o\ ^0£» -lorr

1935. DORMANCY IN SUBTERRANEAN CLOVER. Tas. Jour. Agr. 6 (3) : IJb-l^T.

WORK, P. A a TT 4^

1944 EFFECT OF SHEARING ON PERFORMANCE OF BEET SEED. Amer. Î50C. ±10rr.

Sei. Proc. 45: 418-420.

YOUNG, R. E.

1949. THE EFFECT OF MATURITY AND STORAGE ON GERMINATION OF BUTTERNUT

SQUASH SEED. Amer. Soc. Hort. Sei. Proe. 53: 345-346.

IDENTIFICATION OF SEEDS

1910. SEEDS OF MICHIGAN WEEDS. Mich. Agr. Expt. Sta. P>ul. No. 260. 104-

182. illus.

BELLUE, M. K. ^ .._

No date A COMPILATION FROM WEED SEED HANDBOOK SERIES I-VIII. Oaiit.

* State. Dept. Agr. Bill. Vois. XXXIV, XXXV, and XXXVI. 64 pp.,

illus.

FRANCOIS, L.

1943. SEMENCES ET PREMIERES PHASES DU DéVELOPPEMENT DES PLANTES COMMENSABLES DES VEGETAUX CULTIVES. Stations et Laboratoires de

Reeh. Agron. (Paris) 183 pp. illus.

HELLBO, E.

1926. THE DISTINCTION BETWEEN THE SEEDS OF ITALIAN RYEGRASS AND PERENNIAL RYEGRASS AND BETWEEN SEEDS OF RYEGRASS AND MEADOW

FESCUE. Internat. Seed Test. Assoe. Proc. (2) : 6-15.

HiLLMAN, F. H. CI T> 1 TVT 00

1897. NEVADA AND OTHER WEED SEEDS. Nev. Agr. Expt. Sta. Bui. JNO. do.

131 pp.

HYDE, E. O. C. ^ A T» 1

No date, WEED SEEDS IN AGRICULTURAL SEED. New Zeal. Dept. of Agr. Bui.

No. 316. 48 pp. illus.

ISELY, D.

1947 INVESTIGATIONS IN SEED CLASSIFICATION BY FAMILY CHARACTERISTICS.

Iowa Agr. Expt. Sta. Res. Bui. No. 351. 317-380. illus.

1949. SEED CHARACTERISTICS OF WEEDY THISTLES. Assoc. Off. Seed Anal.

Contrib. to Handbk. on Seed Test. 7 pp. illus.

1949. SEEDS OF IOWA NOXIOUS WEEDS. lowa Agr. Expt. Sta. Bui. P-101

429-454. illus.

KORSMO, E.

1935. WEED SEEDS (also listed under the titles "UGRESSFRO" and 'UNKRAUTSAMEN"). 306 colored illustrations of seeds with descriptions in

English, Norwegian, and German. 175 pp. Gyldendal Norsk Forlag.

Oslo.

MCGUGAN, J. M. . ^ X T> i-.

1948. SEEDS AND SEEDLINGS OF THE GENUS Brassica. Can. Jour. lies, c

26: 520-587. illus.

MURLEY, M. ^ k. A CS '

1944. A SEED KEY TO FOURTEEN SPECIES OF GERANIACEAE. lOWa ACaÜ. feCl.

51: 241-246. illus.

1945 DISTRIBUTION OF EUPHORBIACEAE IN IOWA, WITH SEED KEYS. lOWa

State Col. Jour. Sei. 19: 415-427. illus.

1946 FRUIT KEY TO THE UMBELLIFERAE IN IOWA, WITH PLANT DISTRIBUTION

RECORDS. Iowa State Col. Jour. Sei. 20: 349-364. illus.

1951. SEEDS OF THE CRUCIFERAE OF NORTHEASTERN NORTH AMERICA. Amer.

Midland Naturalist. 46: 1-81.

1942. TESTING FARM SEEDS IN HOME AND SCHOOL. U. S. Dept. Agr. MiSC.

Pub. No. 437. 88 pp., illus.

1942. DISTINGUISHING CHARACTERS OP COMMERCIAL SPECIES OF AgVOSUs AND

CERTAIN SPECIES OCCURRING INCIDENTALLY WITH THEM. ASSOC. Off.

Seed Anal. Proe. (34) : 139-151. ilus.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 311

MusiL, A. F.

1946. THE IDENTIFICATION OF SPECIES OF Poa BY SEED (20 SPECIES). U. S.

Dept. Agr. Prod, and Mktg. Admin. Grain Br. 10 pages and 3 photographic seed plates.

1948. DISTINGUISHING SEEDS OF RYE6RASS, Lolium SPP., AND THE LARGESEEDED FESCUES, Festuca elatior AND VARIETIES. U. S. Dept. Agr.

Pro. and Mktg. Admin. Grain Br. 5 pages and 5 photographic

seed plates.

1948. DISTINGUISHING THE SPECIES OF BrüSSlCa BY THEIR SEED. U. S. Dept.

Agr. Misc. Pub. No. 643. 35 pp. illus.

1948. DISTINGUISHING SPECIES OF AveUa BY SEED ; CULTIVATED OATS, FATUOIDS,

AND CERTAIN WILD SPECIES. Assoc. Off. Seed Anal. Proc. (38) 84-96.

illus.

1948. THE TAxoNOMic STATUS OF AgvopyTon intermedium AS INDICATED BY

A COMPARATIVE STUDY OF ITS SEED AND THAT OF A, trichophorum.

Assoc. Ofe. Seed AnaL Proc. (38) : 79-83. illus.

1949. DISTINGUISHING THE SEEDS OF FINE-LEAVED FESCUES AND CERTAIN WEEDY

SPECIES OCCURRING WITH CROP SEEDS. ASSOC. Off. Seed Anal. Proc

(39) : 93-107. illus.

1950. SOME BRIEF NOTES ON THE IDENTIFICATION OF SEEDS OF FOXTAIL MILLET,

Setaria itálica. Assoc. Off. Seed Anal. Proc. (40) : 55-57. illus!

1950. SEEDS OF Agropyron. ELEVEN SPECIES OF ECONOMIC INTEREST COMPARED

Assoc. Off. Seed Anal. Proc. (40) : 59-71. illus.

1950. IDENTIFICATION OP BRAS SICAS BY SEEDLING GROWTH OF LATER VEGETATIVE

STAGES. U. S. Dept. Agr. Circ. 857. 26 pp. illus.

PARODI, R.

1946. GRAMíNEAS BONARIENSES (KEYS TO GENERA AND ENUMERATION OF

SPECIES). 112 pp. illus. Centro Estudiantes de Agronomía. Buenos

Aires.

PlERPOINT, M.

1949. CERTAIN VETCHES AND SIMILAR PLANTS. Assoc. Off. Seed Anal. Contrib

to Handbk. on Seed Test. 5 pp. illus.

QUISUMBING, E.

1923. GENERAL CHARACTERS OF SOME PHILIPPINE WEED SEEDS. Philippine Agr

Rev. (Manila) 16 (4) : 298-351, illus.

WRIGHT, W. H.

1940. THE SEEDS OF Sofichus. Assoc. Off. Seed Anal. Contrib. Handbk on

Seed Test. 3 pp. illus.

1940. THE SEEDS OF THE GENUS Poa COMMONLY FOUND ON THE MARKET. Assoc. Off. Seed Anal. Contrib. Handbk. on Seed Test. 2 pp. illus.

1940. THE SEEDS OF PERENNIAL RYEGRASS AND MEADOW FESCUE. AsSOC Off

Seed Anal. Contrib. Handbk. on Seed Test. 2 pp. illus.

1941. MILLETS (Panicum, Setaria, AJ^B Pennisetum). Assoc Off Seed Anal

Contrib. Handbk. on Seed Test. 5 pp. illus.

1942. WILD OATS, FALSE WILD OATS, AND HETEROZYGOUS FALSE WILD OATS

Assoc Off. Seed Anal. Contrib. Handbk. on Seed Test. 8 pp. illus!

No date, THE SEEDS OF SILENE AND LYCHNIS. ASSOC. Off. Seed Anal Contrib

Handbk. on Seed Test. 6 pp. illus.

No date, WEED SEEDS, APPROXIMATELY SOO SPECIES ILLUSTRATED IN COLOR-NO

DESCRIPTIONS. In 8 sections. Canadian Dept. Agr. Ottawa,
312 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

TESTING FOR VARIETY

CALDWELL, B.

1947 VARIETY TESTING OF VEGETABLE SEED UNDER THE FEDERAL SEED ACT.

Assoc. Off. Seed AnaL Proe. (37) : 86-88.

DAVIDSON, W. A. . . , x^ /orT^ ^/^ ^o

1935. SEEDLING IDENTIFICATION. Assoc. Off. Seed Anal. Proc. (27) : 40-43.

1950. TESTING SWEET SUDAN GRASS SEED FOR PURITY AND GERMINATION. U. S.

Dept. Agr. Prod, and Mktg. Admin. Instr. No. 959. 8 pp.

TTTSTICE O L

1946. A REVIEW OF LITERATURE ON THE USE OF THE FLUORESCENCE TEST FOR THE

CLASSIFICATION OF LoUuni SPECIES AND HYBRIDS. Assoc. Off*. Seed

AnaL Proc. (36) : 86^93.

NILLSON-LEISSNER, G.

1951. DETERMINATION OF VARIETY AND STRAIN IN THE LABORATORY AND IN THE

FIELD. Internat. Seed Test. Assoc. Proc. 16: 350-351.

NORRIS, E. L. * 1 Ti /o^\

1942. IDENTIFICATION OF SORGHUMS. Assoc, Off. Seed AnaL Proc. {ó'í) :

151-155.

RANDALL, C. G. 1.^ ^ ^ A T> 1

1950. OCCURRENCE OF RED RICE IN CALIFORNIA SEED RICE. Calif. Dept. Agr. l>Ul.

39 (2) : 104-106.

STANTON, T. R.

1940. MAINTAINING IDENTITY AND PURE SEED OF SOUTHERN OAT VARIETIES. U. b.

Dept. Agr. Circ. No. 562. 19 pp., illus.

UNITED STATES DEPARTMENT OF AGRICULTURE.

1948. SOYBEAN VARIETIES. U. S. Dept. Agr. Prod, and Mktg. Admin. 25 pp.

ViNALL, H. N., STEPHENS, J. C, and MARTIN, J. H.

1936 IDENTIFICATION, HISTORY, AND DISTRIBUTION OF COMMON SORGHUM VARIETIES. U. S. Dept. Agr. Tech. Bui. No. 506. 101 pp. illus.

WERTMAN, F. L., and JUSTICE, O. L. ^«. CI ^ A i

1950 VARIETY DETERMINATIONS OF SUDAN GRASS SEED. ASSOC. Ott. feeCÜ Anal.

Proc. (40) : 49-55.

PATHOLOGICAL CONSIDERATIONS

CHRISTEN SEN, J. J., and STAKMAN, B. C.

1935. RELATION OF Fusarium AND Helminthosporium IN BARLEY SEED TO SEEDLING BLIGHT AND YIELD. Phytopath. 25 : 309-327.

CROSIER, W. . „^^ >^«f,

1935 DETECTION AND IDENTIFICATION OF SEED-BORNE PARASITES. ASSOC. Uli.

Seed Anal. Proc. (27) : 87-92.

1944 SOME FUNGI FOUND IN SEEDSTOCKS DURING RECENT YEARS. ASSOC. Off.

Seed Anal. Proc. (35) : 99-102.

1947 THE BLACK FUNGI ON GRAINS OF OATS. Assoc. Off. Seed Anal. News

Letter. 21: 21-25.

and WEIMER, D. C^ i A i

1939 SOME FUNGI FOUND ASSOCIATED WITH GRASS SEED. ASSOC. Ott. hCCd Anal.

Proc. (31) : 120-124.

HARTER, L. L., ZAUMEYER, W. J., and WADE, B. L. , ^ , T, i

1934. PEA DISEASES AND THEIR CONTROL. U. S. Dcpt. Agr. Farmers Bui.

No. 1735. 25 pp.

1926. MANUAL OF PLANT DISEASES. McGraw Hill Book Co., New York. 891

pp., illus.

1942 EXAMINATION OF RYEGRASS SEED FOR BLINDSEED DISEASE. N. Zeal. JOUr.

Agr. 65: 349-350 (also 70: 271-276, 1945).

1943 ' SOYBEAN DISEASES AND THEIR CONTROL. U. S. Dcpt. Agr. Farmers'

Bui. No. 1937. 24 pp.

LEUKEL, R. W., and MARTIN, J. H. ^T C T^ ^ A m i

1943. SEED ROT AND SEEDLING BLIGHT OF SORGHUM. U. b. Dept. Agr. lecll.

Bul. No. 839. 26 pp.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 313

MEEHAN, F., and MURPHY, H. C

1946. A NEW HELMINTHOSPOKIUM BLIGHT OF OATS. Science. 104: 413-414.

NOBT^, M.

1948. SEED-BORNE DISEASES OF CLOVER. British Mycol. Soc. Trans. 30: 84-91.

ORTON, C. R.

1931. SEED-BORNE PARASITES. W. Va. Agr. Expt. Sta. BuL No. 245. 47 pp.

PETHYBRIDGE, G. H., LAFFERTY, H. A., and RHYNEHART, J. G.

1921. INVESTIGATIONS ON FLAX DISEASES. Jour. Dept. Agr. Tech. Inst.

Ireland. 21: 169-175.

POPP, W.

1951. INFECTION IN SEEDS AND SEEDLINGS OF WHEAT AND BARLEY AND RELATION TO DEVELOPMENT OF LOOSE SMUT. Phytopath. 41 I 261-275.

PORTER, R. H.

1932. DETECTION OF SEED-BORNE PARASITES. Assoc. Off. Seed Anal. Proc. (25) :

218-222.

1935. EFFECT OF SEED-BORNE PATHOGENS AND OF SEED DISINFECTANTS ON THE

GERMINATION OF BARLEY SEED. Assoc. Off. Seed Anal. Proc. (27) :

94-99.

1938. DETECTION AND CLASSIFICATION OF SEED-BORNE ORGANISMS, THEIR EFFECT

ON GERMINATION, AND THEIR CONTROL BY SEED DISINFECTION IN LABORATORY AND FIELD. Assoc. Off. Seed Anal. Proc. (30) : 195-213.

HENDERSHOTT, W, E., and DAVIS, G. N.

1938. INDEXING FARMERS' SEJED LOTS FOR SEED-BORNE ORGANISMS AND RESPONSE

TO SEED DISINFECTANTS. lowa Agr. Expt. Sta. Res. Bui. No. 238,

243-272.

WHITEHEAD, M. D., and DICKSON, J. G.

1948. THE INFLUENCE OF GERMINATING TEMPERATURES ON SEEDLING DEVELOPMENT OF HELMINTHOSPORIUM BLIGHT OF OATS. Jour. Amer. Soc

Agron. 40: 1092-1099.

MORPHOLOGY

ANDERSEN, A. M.

1927. DEVELOPMENT OF THE FEMALE GAMETOPHYTE AND CARYOPSES OF Poa

pratensis AND Poa compressa. Jour. Agr. Res. 34: 1001-1018.

AVERY, G. S., JR.

1930. COMPARATIVE ANATOMY AND MORPHOLOGY OF EMBRYOS AND SEEDLINGS OF

MAIZE, OATS, AND WHEAT. Bot. Gaz. 89 : 1-39.

BARBER, K. G.

1909. COMPARATIVE HISTOLOGY OF CERTAIN SPECIES OF CUCURBITACEAE. Bot

Gaz. 47: 263-310.

CLUTE, W. N.

1939. TESTA AND SEED COAT. Amer. Bot. 45 : 75-77.

CoE, H. S., and MARTIN, J. N.

1920. STRUCTURE AND CHEMICAL NATURE OF THE SEED COAT AND ITS RELATION

TO IMPERMEABLE SEEDS OF SWEETCLOVER. U. S. Dept. Agr. Bul. No.

844, 1-39.

COOPER, D. C.

1935. MACROSPOROGENEsis AND EMBRYOLOGY OF Medicago. Jour. Agr. Res

51: 471-477.

HAMLY, H.

1932. SOFTENING OF SEEDS OF McUlotus alia. Bot. Gaz. 93: 345-375

HAYWARD, H. E.

1938. THE STRUCTURE OF ECONOMIC PLANTS. The Macmillau Co. New York

674 pp., illus.

HOLMAN, R. M., and ROBBINS, W. W.

1927. TEXTBOOK OF GENERAL BOTANY. Johu Wiley & Sous, luc New York

624 pp.

LANDES, M.

1946. SEED DEVELOPMENT IN AcalypJia rhomhoidea AND OTHER EUPHORBIACEAE

Amer. Jour. Bot. 33: 562-568.

MARTIN, A. C.

1946. THE COMPARATIVE INTERNAL MORPHOLOGY OF SEEDS. Amer. Mid. Nat.

36: 513—660.
314 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

MARTIN, J. N.

1938. STUDIES ON STRUCTURE OF SEED COAT ENVIRONAL FACTORS PERTAINING TO

GERMINATION OF WEED SEEDS. lOWE Expt. Sta. Rpt. 1 : 109-112.

and WATT, J. R.

1944. THE STROPHIOLE AND OTHER SEED STRUCTURES ASSOCIATED WITH HARDNESS

IN Melilotus alba L. AND oMcinalis WILLD. Iowa State CoL Jour.

Sei. 18: 457-469.

MCCALL, M. A.

1934. DEVELOPMENTAL ANATOMY AND HOMOLOGIES IN WHEAT. JOUT. Agr. ReS.

34: 1001-1018.

PAMMEL, L. H.

1899. ANATOMICAL CHARACTERS OF THE SEEDS OF LEGUMINOSAE, CHIEFLY GENERA

OF GRAY'S MANUAL. Trans. Acad. Sei. St. Louis. 9 : 91-274.

PERCIVAL, J.

1921. THE WHEAT PLANT. Duckworth and Co., London. 463 pp.

RANDOLPH, L. F.

1936. DEVELOPMENTAL MORPHOLOGY OP THE CARYOPSIS IN MAIZE. Jour. Agr.

Res. 53: 881-916.

ROBBINS, W. W.

1924. THE BOTANY OF CROP PLANTS. P. Blakiston's Son & Co. Philadelphia.

164 pp., illus.

SIMPSON, D. M.

1940. ANATOMICAL STRUCTURE OF THE COTTONSEED COAT AS RELATED TO PROBLEMS OF GERMINATION. U. S. Dept. Agr. Tech. Bui. No. 734. 23 pp.

WATSON, D. P.

1948. STRUCTURE OF THE TESTA AND ITS RELATION TO GERMINATION IN THE

Papilionaceae TRIBES TrifoUae AND Loteae. Ann. Bot. 12 (48) :

385-409.

WiNTON, A. L., and WINTON, K. B.

1932. STRUCTURE AND COMPOSITION OF FOODS. Johu Wiley & Sous, Inc. New

York. 710 pp.

SAMPLING

CARTER, A. S.

1947. BUILDING ORCHARD GRASS SEED. Assoc. Off. Seed Anal. News Letter.

21 (1) : 38-40.

CASEY, J. E.

1948. ALL COMMERCIAL SEED STOCKS NOT UNIFORM. Assoc. Off. Seed Anal.

Proc. (38) : 28-30.

1948. ANALYSES OF LESPEDEZA SEED SAMPLES DRAWN WITH 9-INCH AND 30-INCH

TRIERS. Assoc. Off. Seed Anal. Proc. (38) : 40-45.

JUSTICE, O. L.

1950. SECOND ANNUAL PROGRESS REPORT ON RESEARCH CONDUCTED UNDER RESEARCH AND MARKETING ACT PROJECT 355. Assoc. Off. Seed Anal.

Proc. (40) : 44-47.

LEGGATT, C. W.

1932. A NEW SAMPLER FOR SAMPLING SEED IN THE SACK. AsSOC. Off. Seed

Anal. Proc. (25) : 192-195.

1941. A STUDY OF THE RELATIVE EFFICIENCY OF SEED SAMPLING METHODS. CaU.

Jour. Res. C. 19 (5) : 156-162.

1946. BULKING OF SAMPLES TO OBTAIN A GIVEN QUALITY. ASSOC. Off. Seed Anal.

Proc (36) : 69-76.

1948. REPORT OF THE SUBCOMMITTEE ON MIXING AND SAMPLING. AsSOC. Off.

Seed Anal. Proc. (38) : 26-27.

1950. REPORT OF THE SUBCOMMITTEE ON MIXING AND SAMPLING. ASSOC. Off.

Seed Anal. Proc. (40) : 23-30.

MuNN, M. T.

1938. OBSERVATIONS UPON THE MOVEMENT OF SEEDS IN BAGS WHEN SAMPLED

WITH INSTRUMENTS. Assoc. Off. Seed Anal. Proc. (26) : 278-279.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 315

SCHENBERGER,, L. C, CAKTEK, A. S., and QUACKENBUSH, F. W.

1946. A STUDY OF METHODS OF SEED SAMPLING. Assoc. Off. Seed Anal. Proc.

(36) : 56-68.

WRIGHT, W. H.

1935. AN EXPERIMENT IN SAMPLING. Internat. Seed Test. Assoc. Proc.

7 (1) : 19-20, illus.

TOLERANCES AND STATISTICS

AitKiN, H., and COLTON, R. C.

1939. AN OUTLINE OF STATISTICAL METHODS. 4tli Edition. Barnes and

Noble, Inc., New York, N. Y.

COCHRAN, R. G.

1941. TEST FOR HOMOGENEITY IN SEED GERMINATION TESTS. PrOC. Off. Seed

Anal. Proc. (33) : 60-63.

COLLINS, G. N.

1929. THE APPLICATION OF STATISTICAL METHODS TO SEED TESTING. U. S. DCPT.

Agr. Oirc. No. 79. 18 pp.

FISHER, R. A.

1930. STATISTICAL METHODS FOR RESEARCH WORKERS. 3d Edition. Oliver

S. Bard. Edinburgh. 283 pp.

LEGGATT, C. W.

1930. VARIATIONS IN PURITY ANALYSES AND OF GERMINATION TESTS AS INFLUENCED BY SAMPLING. Assoc. Off. Seed Anal. Proc. (23) : 42-45.

1935. CONTRIBUTIONS TO THE STUDY OF THE STATISTICS OF SEED TESTING.

I. THE APPLICABILITY OF THE POISSON DISTRIBUTION IN IHE STUDY OF

CERTAIN PROBLEMS IN SEED ANALYSIS.

:ST AS A BASIS FOR COMPUTING GERMINÜ

Internat. Seed Test. Assoc. Proc. 7 : 27-48.

1935. CONTRIBUTIONS TO THE STUDY OF THE STATISTICS OF SEED TESTING.

III. A THEORETICAL STUDY OF PURITY TOLERANCE WITH SPECIAL

REFERENCE TO THE TOLERANCE OF PURE SEED. IntCmat.

Seed Test. Assoc. Proc. 27: 101-107.

1939. STATISTICAL ASPECTS OF SEED ANALYSES. Bot. RCV. 5 : 505-529.

1932. CONTRIBUTION TO THE STUDY OF THE STATISTICS OF SEED TESTING.

VIII. STUDIES ON THE DISTRIBUTION OF RESULTS OF GERMINATION

TESTS, Internat. Seed Test Assoc. Proc. 2: 140-150.

MuNN, M. T.

1932. THE TOLERANCE FORMULAE IN THE INTERNATIONAL SEED TESTING RULES.

THEIR USE AND APPLICATION TOGETHER WITH TABLES OF TOLERANCES

AND LATITUDES. Internat. Seed Test. Assoc. (1) : 1-10.

PORTER, R. H.

1937. APPLICATION OF THE CHI-SQUARE TEST TO PURITY ANALYSIS OF BLUEGRASS

SEED. Assoc. Off. Seed Anal. Proc. 29: 91-93.

SMITH, C. P.

1917. STUDIES IN TOLERANCES FOR PURITY VARIATIONS. Assoc. Off. Seed Anal

Proc. 9: 18-21.

SNEDECOR, G. W.

1940. STATISTICAL METHODS. 3d Edition. Iowa State College Press. Ames,

Iowa. 422 pp.

YOUDEN, W. J.

1932. STATISTICAL ANALYSIS OF SEED GERMINATION THROUGH THE USE OF THE

CHI-SQUARE TEST. Contrib. Boyce Thomp. Inst. 4: 219-232.

EQUIPMENT

BOERNER, E. G.

1915. A DEVICE FOR SAMPLING GRAIN, SEEDS, AND OTHER MATERIAL. U. S Dept

Agr. Bui. No. 287. 4 pp., illus.

BROWN, E., TOOLE, E. H., and Goss, W. D.

1928. A SEED COUNTER. U. S. Dept. Agr. Circ. No. 53. 3 pp., illus.
316 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

CASEY, J. E.

1948. ANALYSES OF LESPEDEZA SEED SAMPLES DRAWN WITH 9-INCH AND 30-INCH

TEiEßS. Assoc. Off. Seed Anal. Proc. (38) : 4CM5.

EKICKSON, E. L.

1944. THE SOUTH DAKOTA SEED BLOWER. Assoc. Off. Seed Anal. Proe. (35) :

91-95. illus.

GADDIE, R. C.

1946. NEW TYPE SEED WASHER (BEETS). Seed World. 60 (9) : 18-20.

GRAIN BRANCH, PRODUCTION AND MARKETINCX ADMINISTRATION.

No date, SPECIFICATIONS FOR WATER-COOLED AND AIR-COOLED SEED GERMINATION

CABINETS. U. S. Dept. Agr. 17 pp., 2 photos, 2 blueprints.

HOLMES, F. S.

1927. A SEED COUNTING APPARATUS. Assoc. Off. Seed Anal. News Letter.

1 (1) : 6-7.

JUSTICE, O. L.

1946 AN AIR CONDITIONED SEED GERMINATOR AND FLUORESCENT LIGHT GRIDS TO

REPLACE DAYLIGHT. Assoc. Off. Seed Anal. Proc. (36) : 107-111, illus.

1947 FURTHER NOTES ON THE USE OP FLUORESCENT LIGHTS IN GERMINATION

CHAMBERS. Assoc. Off. Seed Anal. Proc. (37) : 101-103, illus.

1949. A COMPARISON OF SOME ULTRAVIOLET LAMPS IN TESTING RYEGRASS FOR

FLUORESCENCE. Assoc. Off. Seed Anal. Proc. (39) : 89-92.

KJAER, A. -r f^rt /ON

1948. THE JACOBSEN GERMINATOR. Assoc. Off. Seed Anal. News Letter. 22 (2) :

44-45.

LEGGATT C. W.

1938. A NEW SEED BLOWER. Assoc. Off. Seed Anal. Proc. (30) : 120-132.

1950. A PROPORTIONING SEED MIXER AND SAMPLER. Assoc. Off. Seed Anal. Proc.

(40) : 47-49. illus.

MUNN, M. T. ^^ ^^

1950. A METHOD FOR TESTING THE GERMINABILITY OF LARGE SEEDS. N. X.

(Geneva) Agr. Expt. Sta. Bui. No. 470. 10 pp.

NUTILE, G. E. A ^«! d 1

1945. A SIMPLE BEET *'SEED" WASHER FOR THE LABORATORY. AsSOC Oft. bced

Anal. News Letter. 19 (4) : 4-5.

PORTFTt R H

1938 UNIFORM TECHNIQUES FOR THE ANALYSIS OF SMALL-SEEDED GRASSES.

Assoc. Off. Seed Anal. Proc (30) 131-171.

SCHENBERGER, L. C. 4 ^.aj « ^ A «i

1950 WHAT ''GOES ON" INSIDE THE SEED GERMINATOR. Assoc. Off. Seed Anal.

Proc. (40) : 71-76.

BALBACH, P., and FORD, O. W.

1947. A MODIFIED VERTICAL SEED BLOWER. Assoc. Off. Seed Anal. Proc {01} :

104-106. illus.

PAGE, G. E., and CARTER, A. S.

1947 DESIGN AND CONSTRUCTION OF A LOW TEMPERATURE GERMINATOR. ASSOC.

Off. Seed Anal. Proc (37) : 99-101. illus.

ORIGIN

OTîTSCIT A.

1943 DIE HERKUNFTSBESTIMMUNG DER KLEE- UND GRASSAMEN. Internat.

Seed Test. Assoc Proc 13 : 147-416. illus.

HiLLMAN, F. H., and HENRY, H.

1928 THE INCIDENTAL SEEDS FOUND IN COMMERCIAL SEED OF ALFALFA AND RED

CLOVER. Internat. Seed Test. Assoc Proc (1928) No. 6: 1-22.

WAHLEN, F. T.

1928 A SURVEY OF WEED SEED IMPURITIES OF AGRICULTURAL SEED PRODUCED IN

CANADA, WITH SPECIAL REFERENCE TO THE DETERMINATION OF ORIGIN.

Internat. Seed Test. Assoc. Proc. (1928) No. 6: 19-66.

GENERAL

1942.' FOREST TREE SEED. Chrouica Botánica. Waltham, Mass. 240 pp.
Tî:STING AGRICULTURAL AND VEGETABLE SEEDS 317

FINGERLING, G.

1928. TECHNISCHE VORSCHRIFTEN FÜR DIE PRÜFUNG VON SAATGUT. LaildW.

Versuchs. Stat. 107: 1-46.

FOREST SERVICE, UNITED STATES DEPARTMENT OF AGRICULTURE.

1948. WOODY-PLANT SEED MANUAL. U. S. Dept. Agr. Misc. Pub. No. 654. 416

pp., illus.

INTERNATIONAL SEED TESTING ASSOCIATION.

1938. INTERNATIONAL RULES FOR SEED TESTING. Internat. Seed Test. Assoc.

Proc. 10 (1) : 407-432.

JUSTICE, O. L.

1950. THE TESTING FOR PURITY AND GERMINATION OF SEED OFFERED FOR IMPORTATION INTO THE UNITED STATES. Internat. Seed Test. Assoc. Proc. 16 :

150-172.

MERCER, S. P.

1948. FARM AND GARDEN SEEDS. Crosby Lockvi^ood and Son, Ltd. London.

156 pp., illus.

MusiL, A. F.

1942. TESTING FARM SEEDS IN HOME AND SCHOOL. U. S. Dept. Agr. MiSC. Pub.

No. 437. 88 pp., illus.

PORTER, R. H.

1944. TESTING THE QUALITY OF SEEDS FOR FARM AND GARDEN. loVS^a Agr. Expt.

Sta. Res. BuL 334. 495-586. illus.

1949. RECENT DEVELOPMENT IN SEED TECHNOLOGY. BOT. REV. 15 : 221-344.

REMINGTON, J. S.

1928. SEED TESTING. Isaac Pittman and Sons, Ltd. London. 144 pp., illus.

SANDERS, C. B.

1923. METHODS OF SEED ANALYSIS. Nat'l lust. Agr. Bot. 15 pp. Cambridge

Univ., England.

SMIRNOVA, A. L., ET AL.

1943. RULES FOR THE ANALYSIS OF SEEDS. (In RuSSiaU.) MOSCOW. 159 pp.,

illus.

957116—52-
AVAILABLE PUBLICATIONS ON SEED TESTING

The following publications are available upon request from the

Seed Act Division, Grain Branch, Production and Marketing Administration, U. S. Department of Agriculture, Washington 25, D. C.

(In requesting these publications refer to each by title) :

Specifications for (a) Air-conditioned Germination Cabinets, (b) Water-cooled

Germination Cabinets, (c) Fluorescent Light Grids. These specifications include descriptions, photostatic copies of diagrams, and photographs.

A Selected List of Books and Other Publications for Seed Testing Laboratories.

This list includes books useful in seed testing, from various fields of the

plant sciences.

List of Photographs Showing Normal and Abnormal SeedUngs. Approximately

150 photographs are listed by negative number, kind of seed, and nature of

seedlings illustrated. These photographs are available through purchase.

A Partial List of Firms Handling Seed-Testing Equipment and Supplies. Names

and addresses of firms are given for each kind of laboratory apparatus and

various supplies ordinarily used in seed testing.

List of Publications on the Identification of Seeds. This is a list of photographs

of seeds and descriptive material. These photographs are avaüable by

purchase.

Diagram for Constructing Purity Workboard.

Testing Sweet Sudan Grass Seed for Purity and Germination. This circular

describes the detailed procedure adopted by the Seed Act Division, and includes

instructions for ordering color transparencies and a standard color chart used

in making tests. .

Service and Regulatory Announcements No. 156. This publication contains the

text of the Federal Seed Act and the Rules and Regulations Thereunder. The

rules for seed testing are included.

Requirements for LabeUng Agricultural Seeds and Vegetable Seeds, and Suggested

Forms of Labels. ....... ^ .i. State Noxious-weed Seed Requirements Recognized in the Administration of the

Federal Seed Act. . , ^ ,

Seed List—A List of Agricultural and Vegetable Seeds and the Incidental Seeds

Commonly Found With Them. , ^r. , . ^

A Partial List of Rapid Moisture-Testing Devices for Grain and Related

Commodities.

318
GLOSSARY

AcermiU.—^A cushionlike mass of liyphae having conidiophores,

conidia, and sometimes setae.

Achene,—A small, dry, hard, one-chambered, one-seeded indéhiscent

fruit, as in buckwheat, lettuce, and spinach; commonly referred

to as a seed.

Acuminate.—Gradually tapering to a sharp point.

Acute,—Sharp-pointed butless tapering than acuminate.

Adnate.—^United, as an inferior ovary with the calyx tube.

Adventitious (roots).—Those that arise from any structure other

than a root.

After-ripening.—^A period following maturity during which certain

species of seeds undergo si)eciñc physiological changes before

germination is possible.

Aleurone cells.—Cells forming outermost layer of endosperm.

Amino acid.—An acid obtained from proteins by hydrolysis.

Amphitropous {ovule).—Having the ovule inverted, but with the attachment near the middle of one side ; half anatropous.

Anastamosing.—Connecting so as to form a well-defined network.

Anatropous {ovule).—Eeferring to an ovule in which the nucellus

is inverted and straight, with the micropyle adjacent to the

hilum.

Antipodal {cells).—Referring to those cells or nuclei which occupy

the chalazal end of the megagametophyte or embryo sac.

Anther.—The portion of the stamen containing the pollen, usually

bilocular.

Ascospore.—^A spore produced in an ascus or saclike cell.

5^/16^.—Two-cleft.

Bruchid.—One of the weevils {Bruchis hrachialis Fahr.) which attack vetch seed.

BuTblet.—A small bulb, usually axillary, especially one borne upon

the stem.

Callus.—^A hard protuberance or calloused area. In the grass family

it is a hard swollen area at the base or point of insertion of the

lemma or palea, often with hairs.

Calyx.—The outermost cycle of floral parts; the sepals considered

collectively.

Cambium.—Meristematic tissue which gives rise to secondary phloem

and xylem.

Canker.—Result of a disease in which there is sharply limited necrosis

of the cortical tissue.

Carbohydrates.—A class of food substance containing carbon, hydrogen, and oxygen including starches and sugars.

Carpel.—^A simple pistil, or a member of a compound pistil.

Caryopsis.—^A fruit developed from a single carpel with pericarp

united to the seed ; the fruit of cereals and grasses.

319
320 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Campylotropous {ovule).—An ovule in which the nucellus is curved

and the chalaza and micropyle are in a plane at right angles to

the funiculus.

Cellulose,—Material of which cell walls are mainly composed.

Ohalaza,—That part of an ovule or seed where the nucellus is not separated from the integuments ; it is the base of the nucellus and is

always opposite the upper end of the cotyledons ; it is evident

on the surface of seeds of many legumes as a distinct spot or

elevation.

Chalcid fly.—An insect, Bruchophagus gïbhus Boh., which in the

larval or pupal stage causes much damage in clover or alfalfa

seed.

Ohlamydospore.—^A thick-walled intercalary or terminal spore

formed by the rounding up of a cell or cells.

Chlorophyll.—The green coloring matter of plants.

Chromosome.—One of the small bodies, ordinarily definite in number in the cells of a given species and often more or less characteristic in shape, into which the chromatin of the cell nucleus

resolves itself previous to mitotic division of the cell.

Ciliate.—Fringed with hairs on the margin, like eyelashes.

Cleistogene.—Flowers or florets that have been fertilized without

opening.

Cold test.—A germination test in which seeds are planted for a period

in cool, moist, unsterilized soil before transfer to a higher temperature, designed to approximate possible unfavorable planting

conditions in order to determine seedling vigor.

Coleorhiza.—The sheath which surrounds the primary root in the

embryo of grasses.

Coleoptile (in Gramineae).—The first leaf above the cotyledon which

encloses the stem tip and other leaves ; sheath. ^ Composite sample.—A seed sample composed by mixing different subsamples taken from various parts of a seed lot.

Conidia.—An asexual spore which when mature comes away from its

conidiophore.

Conidiophore.—K simple or branched hypha on which conidia are

produced.

Convolute.—Having one part wholly rolled up longitudinally within

another.

Corolla.—The inner cycle of the perianth ; the petals considered collectively.

Cotyledon.—Th^ first leaves of the embryo, one in monocotyledons,

two or more in dicotyledons.

Culm.—The stem of grasses,

Cutin.—A waxlike substance in the epidermal cells of plant parts

which repels liquids from passing through cell walls.

Domhping-off.—The collapse of seedlings, ascribed to the attacks of

such fungus organisms as Botrytis vulgaris and Pythium spp.

Dead seed.—Seeds incapable of germinating.

Dehiscent.—Fruits which split open regularly along certain lines to

discharge the seeds.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 321

Diaphanoscope,—A dark box, or purity work board, having a small

opening in its top, through which a beam of light passes from below ; used principally for determining the presence or absence of

caryopses within the glumes in certain grass seed samples.

Diastase,—A collective enzyme which changes starches into sugars

and sugars into starches.

Diootyledon.—Having two cotyledons.

Diploid,—Having a double number of chromosomes (2N).

Dormant seed.—A viable seed which is inactive because it has not

been given the usual conditions for germination ; as used in this

manual it refers to a seed which resists germination when given

the usual conditions for germination.

Dormancy.—Delayed germination or growth ; a condition of inactivity.

Elliptic.—Oblong with flowing lines, the two ends pointed and approximately alike in width.

Elliptic^ narrowly.—About twice as long as broad.

Elliptic.^ hroadly.—Length only slightly more than width.

Emhryo.—The rudimentary plant formed in a seed; germ.

Endosperm.—The reserve, stored food of seeds, outside the embryo;

referred to as "albumen" by older writersEnzym^e.—K complex substance probably protein in nature produced

by living cells and active as catalysts accelerating or retarding

chemical reactions.

Epicotyl.—That portion of an embryo or seedling above the cotyledons

or cotyledonary node ; plumule.

Epigeal.—^Plants in which the cotyledons appear above the surface of

the soil.

Epithelvu/m.—A cellular tissue serving as an epidermis.

Ergot.—A substance produced by a fungus which takes the place of

the grain in rye and other grasses.

Filament.—The part of the stamen supporting the anther.

Filiform.—Threadlike, slender.

Floret.—In grasses, the lemma and palea with included flower

(stamens and pistil).

Fluorescence.—The property of substances of becoming luminous

when exposed to ultraviolet and other forms of radiant energy.

Foreign seeds.-^^ç^^às of weeds and crops other than the kind under

consideration or being tested.

Free-flowing seeds.—-l^onoh^ñj.^ smooth seeds which will travel easily

through sampling or mixing devices.

Funiculus.—The stalk by which the ovule or seed is attached to the

placenta of the ovary.

Fruit.—The mature ovary and any associated parts.

Gall.—Swelling or excrescence of the tissue of plants resulting from

the attacks of certain parasites ; or seed structures in which the

contents have been replaced by nematodes or eelworms.

Gametophyte.—The generation in the life history of a plant which

usually comes from a spore ; characterized by haploid chromosome

number ; ultimately produces gametes.

Geniculate.—Bent abruptly, like a knee.

Genotype.—Alike in genetic characters.
322 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Gei^m plasm.—The assumed reproductive substance contained in the

body of the parent from which new individuals arise ; nucleus of

the zygote.

Germinable,—Possibility of termination.

Germination.—R^sum^uow ot active growth by the embryo in a seed.

In seed testing : The emergence and development from the seed

embryo of those essential structures which, for the kind of seed

in question, are indicative of its ability to produce a normal plant

under favorable conditions.

Germination percentage.—The percentage of the pure seed of the

kind under consideration which produces normal seedlings.

Glabrous.—^Devoid of hairs.

Globose.—Spherical or nearly so.

Glumes.—The pair of bracts at the base of a spikelet in grasses.

Granular.—Surface roughened by minute granules.

Haploid.—Hü.ymg the basic chromosome number for the species.

Hard seed.—Seeds which remain hard at the end of the prescribed test

because they have not absorbed water, owing to an impermeable

seed coat.

Hemitropous {ovule).—An ovule which is inverted with a straight

nucellus and the micropyle and chalaza are at right angles to

the.funiculus.

Hilum.—^A scar left where the seed stalk or funiculus breaks away,

or where the seed was attached directly to the placenta when

there is no seed-stalk.

Hirsute.—Pubescent with straight, rather stiff hairs.

Hispid.—Pubescent with stiff or rigid hairs.

Histogen.—^Kegions or layers of meristematic tissue from which primary tissues are derived.

Hyaline.—^Having no color ; thin and transparent.

Hydrolysis.—^A decomposition reaction caused by water.

Hypha.—One of the threads of a fungus mycelium.

Hy^yocotyl.—The part of the embryo or seedling below the cotyledonary node and above the root; the transition region connecting

the stem and root.

Hypogeal.—Plants in which the cotyledons remain below the surface

of the soil.

Imbibition.—Absorption of moisture by a colloidal substance such

as seed coats which is accompanied by swelling of the tissue.

Immature {seeds) .—Not fully developed ; not having parts developed.

Inhibit.—To hold back ; to check ; to restrain ; hinder.

Indéhiscent.—Fruits which do not open at maturity.

Inert nhatter.—^As used in seed testing : Kefers to all foreign matter

not seeds, such as stones, sticks, sterile florets, chaff, fungus bodies,

and pieces of seeds not more than one-half the original seed.

Integument.—^\ve envelope of an ovule, later becoming a part of the

seed coat.

Interpretation {germination).—A seed shall be considered to have

germinated when it has developed into a normal seedling.

Broken seedlings and Aveak, malformed, and obviously abnormal

seedlings shall not be considered to have germinated.

Irwolucre.—^A ring of bracts surrounding several flowers or their

supports, as in the heads of Compositae or the umbels of Umbelliferae.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 323

Involute,—Having edges of leaves rolled inwards.

Keel.—A sharp longitudinal fold, like the ridge of a boat.

Lance-shaped.—Longer than wide and tapering to both ends, but

broader at the base.

Lam^ceolate.—Narrowly lance-shaped.

LoÁXí.—Soft, drooping.

Lemma.—The outer bract of the flow^er of grasses, sometimes referred

to as the flowering glume.

Lesion.—A wound ; a well-marked but limited diseased area.

Lignin.—A substance related to cellulose which with it constitutes the

essential part of woody tissue.

Lipase.—An enzyme which brings about hydrolysis of fats to glycerol

and fatty acids.

Maoroconidia.—The larger conidia, when there are conidia of two

sizes.

Malpighian cells.—A protective layer of close packed, heavy-walled

columnar cells found in most seed coats of legumes.

Manometer.—An instrument for measuring the pressure of gases and

vapors. It is used in measuring air pressure in conjunction with

certain seed blowers.

Megagamete.—The larger of two uniting cells or gametes; the egg.

Megaspore.—^A tetraspore from which the megagametophyte develops.

Megaspore mother cell.—A specialized cell in the nucellus giving rise

to four megaspores.

Meristem.—A group of embryonic cells w^iose derivatives may differentiate into various cell types and tissues.

Mericarp.—One of the two carpels of the fruit of an umbelliferous

plant.

Micropyle.—The opening from outside the seed leading through the

integuments to the nucellus ; it marks the position of the radicle.

Microspore mother cell.—Special cells in the anther which give rise

to the pollen grain.

Monocotyledon.—Having one cotyledon.

Morphology {seed).—The study of the form and structure of seed

parts.

Muriform.—Having cross and longitudinal septa.

Mycelium.—A mass of hyphae.

Necrotic.—Death of plant cells, especially when resulting in the tissues

becoming dark in color.

Nematodes.—Threadlike roundworms that live in soil and water

and belong to the Nemathelminthes.

Noxious-weed seed.—Seeds from any plant considered to be extremely

destructive or harmful to agriculture. These seeds are designated

by law for State and Federal law enforcement.

Noxious-weed seed., primary.—Seed from noxious-weed plants restricted by law from being present in any quantity in agricultural

seeds.

Noxious-weed seed., prohibited.—See noxious-weed seed, primary.

Noxious-weed seed., secondary.—Seed from noxious-weed plants permitted by law to be present in limited numbers in agricultural

seeds.

Nucellus.—The bod}^ of the ovule containing the embryo sac.
324 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Nucleus,—A clearly differentiated portion of the protoplasm which

carries hereditary material and is essential to many of the activities of the cell.

Ohclavate,—^Inversely club-shaped (widest at the base).

Oilong,—^About twice as long as broad, sides nearly parallel or somewhat curving, ends obtusely pointed.

Oiovate,—Egg-shape inverted, the broader end at the top.

Ohtuse,—Broad and rounded at the apex, or terminating in a short,

blunt point in contrast to acute.

Optimum conditions.—The environmental factors, such as temperatures, light, and moisture, which are most conducive to the vital

activities of a given organism.

Orbicular,—Length and width approximately equal, and scarcely

tapering at the ends.

Origin {seed).—State or country where seed is grown.

Orihotropous {ovule).—Referring to an ovule in which the nucellus

is erect with the micropyle farthest from the hilum, in a straight

line with it and the chalaza ; also called atropous.

Osteosclerid cells.—A layer of cells beneath the jÇiialpighian cells'

(palisade cells) in the outer integument of legume seeds.

Other crop seeds.—Seeds which are grown as crops other than the

kind of seed on which the test is being made.

Oval.—Length only slightly more than width.

Ovary.—The part of the pistil that contains the ovule or ovules.

Ovate.—Egg-shaped, the broader end at the base.

Ovule.—The nucellus enclosed in its integuments ; the structure which

after fertilization develops into a seed.

Ovule {types).—See Anatropous, Amphitropous, Campylotropous,

and Orthotropous.

Oxidase.—General name for a class of enzymes which catalyze oxidative reactions within the cell, such as in the process of respiration.

Palea.—The tiny upper bract which with the lemma encloses the

flower in grasses.

Palisade cells.—Outermost layer of cells in the outer integument or

seed coat in legumes.

Parasite {fungi).—Fungi which obtain nutrients from living tissue of

their hosts.

Parenchyma.—Simple nonspecialized cellular tissue of plants.

Pectin.—^A chemical constituent of the cell walls of plants.

Pedicel.—The stalk of a spikelet.

Perianth.—The floral envelope comprised of the calyx and corolla

(if present) regardless of their form.

Pericarp.—^The mature ovary wall.

Perithecium.—A flask-shaped structure with an ostiole or opening

containing asci and paraphyses or sterile hyphae.

Petal.-^One of the members of the corolla.

Phenotype.—Alike in obvious physical characters.^

Phloem.—Complex vascular tissue in plants which includes sieve

tubes and conducts food materials.

Physiology {seed).—The study of the functions and activities of

seeds.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 325

Pistil,—^A carpel or group of undiverged carpels, commonly subdivided into stigma, style, and ovary.

Pitted,,—Marked with small depressions or pits.

Pollen,—The fertilizing powder contained in the anther.

Pollination,—The transference of pollen from the anthers to the stigmas of flowers.

Prechill,—To place seeds on a moist substratum and hold at a low

temperature, usually 10° C., for a definite period of time before

transferring theni to a higher germination temperature.

Propagate,—To multiply or increase.

Protease,—^A collective enzyme which brings about hydrolysis of proteins to amino acids.

Protein,—Complex organic compounds which contain oxygen, hydrogen, carbon, nitrogen, and generally sulfur; essential for production of new protoplasm.

Pubescent,—Covered with soft, short hairs.

Pure-live se^iZ.—Percentage of pure germinating seed; determined

by multiplying the pure seed percentage by its own germination

percentage and dividing the product by 100.

Pure seed,—The principal named kind, variety, or type of seed in a

seed lot.

Pycnidia,—^A globose structure with an opening or pore termed ostiole, containing pycnospores.

Rachilla,—ThQ axis of a grass spikelet; the small stem on which the

flower or floretis borne as opposed to the central axis or rachis.

Radial,—Pertaining to or resembling a ray or radius.

Radicle,—^The rudimentary root of the embryo.

Raphe,—A line or ridge of the ovule which runs from the hilum to

the chalaza in anatropous and amphitropous seeds.

Receptacle,—The portion of the axis from which the floral parts arise ;

the torus.

Rudimentary (emhryo) ,—Aii embryo which is imperfectly developed

and functionally useless.

Saprophyte (fungi) .—Fungi which obtain nutrients from dead material or nonliving tissues of their hosts.

Scabrous,—Eough to the touch, covered with minute points or very

shortstiff hairs.

Scarify,—To scratch or roughen the hard seed coat (generally of

legumes) in order to aid germination.

SchÍ3ocarp,—A fruit derived from a compound pistil in which the

one-seeded carpels separate from one another at maturity, as in

the^Umbelliferae.

Sclerotia,—^A firm frequently rounded mass of hyphae with or without the addition of host tissue normally having no spores in or

on it.

Scutellum,—The cotyledon of an embryo of a grass; a food absorbing

structure.

Seed,—^An embryo or embryos with or without an external food reserve surrounded by one or two integuments.

Seed (kind) .—One or more related species or subspecies which singly

or collectively is known by one common name.

Seed lot.—^A uniformly blended quantity of seed designated by a

proper number or mark.
326 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

ßeed^ other crop.—Seeds of plants grown as crops other than the kind,

variety, or type included in the x)ure seed.

Seed stocks,—^A marked variety which may be perpetuated from seed.

Seed technology,—Science of seed testing.

Seeds^ agricultural.—Includes all grass, forage, and field crop seeds.

Seeds^ vegetable—Seeds generally grown in gardens or on truck farms.

Seedling.—The embryo or young plant from the time it emerges from

the seed until it is entirely dependent on food manufactured by

itself. It consists of an epicotyl, one or two cotyledons, hypocotyl, and root; the single cotyledon is usually held within the

seed coat in monocots.

Seedling., ainormal.—RsiYmg weak or malformed parts, such as stubby

roots, split hypocotyls, absence of primary leaves, and absence of

terminal bud; not potentially capable of producing a normal

plant under favorable growing conditions.

Seedling^ normal.—Having healthy, well-formed structures, such as

epicotyl, one or two cotyledons, hypocotyl, and root ; potentially

capable of producing a healthy plant under favorable growing

conditions.

Sepal.—One of the members of the calyx.

Sessile.—^With or without a pedicel or stalk.

Sinus.—The space between the margin of lemma above the point of

attachment to the rachilla.

Smooth.—Not rough to the touch.

Spatulate.—Broad and rounded at the apex, narrowed toward the

base.

Spihelet.—The unit of influorescence in grasses, consisting of two

glumes and one or more florets.

Sporophyte.—The plant as it is commonly known, having the diploid

chromosome number.

Stamen.—A pollen-bearing organ.

Stellate.—Star-shaped.

Stereoscopic microscope.—A microscope having two oculars which

give depth to the object being viewed, or the appearance of

solidity.

Stigma,—The receptive portion of the pistil.

Striate.—^Marked with slender longitudinal grooves or lines.

Strophiole.—A swollen appendage at the hilum of some seeds.

Style.~T\iQ usually elongated portion of the pistil connecting the

stigma and ovary.

Stroma.—A mass of vegetative hyphae with or without tissue of the

host or substratum, sometimes sclerotiumlike in form, in or on

which spores are produced.

Suberin.—A fatty substance found between cell walls which renders

cells almost or entirely impermeable to water.

Substratum.—The material upon which seeds are placed for a germination test.

Suture.—A line of splitting or dehiscence.

Smollen seed,—Seeds which have imbibed water and although healthy

in appearance, have not germinated during the prescribed test

period.

Synergids.—The nuclei or cells adjacent to the ^gg cell at the micropylar end of the embryo sac.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 327

Tangential,—Kt right angles to the radius or radial rays.

Temperature^ alternating,—h\ germination testing, specific temperatures with seeds being held at both the lower and higher temperatures for a designated time each day.

Temperature^ constant.—In germination testing, a specific temperature which should not vary by more than 1° C.

Testa,—Hard outer seed coat or seed coats.

Tolerance,—^A specified or calculated allowance for sampling variation and sometimes experimental error.

Toxic,—Acting, or likely to act as a poison.

Transversely,—^Across, horizontal.

Tubercle,—A small projection.

Truncate—Ending abruptly, as if cut off horizontally.

Undulate.—With a w^avy surface.

Viability,—Ability to live, grow, and develop.

Villous.—Bearing long and soft hairs.

Vigor.—Strength or force of seedling and plant growth ; as, a plant

grows with vigor.

Web, basal—A tuft of long hairs attached at one point just above the

callus in certain bluegrasses.

Weed seed,—Seed of any troublesome plant which occurs without

intentional cultivation.

Woolly,—C\ot]ieA with long and entangled soft hairs.

Working sample,—A specified weight of seed on which a purity

analysis is made.

Xylem,—K complex vascular tissue in plants including tracheids and

vessels in which water is conducted.

Zygote,—The product of the union of two gametes; a fertilized egg.
APPENDIX

RULES FOR TESTING SEEDS

SAMPLING

Ordinarily, it is not the duty of the analyst nor does he have the

opportunity to take samples, but he should be prepared to suggest the

best sampling procedure. No matter how accurately an analysis is

made, it can show only the quality of the sample submitted ; therefore,

every effort should be made to insure that the sample furnished

represents the bulk of the seed to be tested.

General Procedure

{a) In order to secure a representative sample, equal portions shall

be taken from evenly distributed parts of the quantity of seed to be

sampled. Access shall be had to all parts of that quantity.

(b) For free-flowing seeds in bags or bulk, a probe or trier shall be

used. For small free-flowing seeds in bags a probe or trier long

enough to sample all portions of the bag shall be used.

{c) Non-free-flowing seeds, such as certain grass seed, uncleaned

seed, or screenings, difficult to sample with a probe or trier, shall be

sampled by thrusting the hand into the bulk and withdrawing

representative portions.

(d) Composite samples shall be obtained to determine the quality

of a lot of seed (thatis, percentages of pure seed, other crop seed, weed

seed, inert matter, and germination). Individual-bag samples may be

obtained to determine whether the lot of seed is uniform.

(1) To determine whether there is an obvious lack of uniformity

of seed from which a composite sample is being obtained, each portion

shall be examined and the portions shall then be combined to form a

composite sample or samples.

(2) If the lot is found not to be uniform when obtaining a composite sample to determine its quality then additional individual-bag

samples shall be taken for the purpose of testing for uniformity. Such

individual-bag samples may also be taken for the purpose of testing

for uniformity even though a composite sample has not previously

been obtained. The identity of each individual-bag sample must be

maintained.

Bulk

Bulk seeds shall be sampled by inserting a long probe or by thrusting

the hand into the bulk, as circumstances require, in at least seven

uniformly distributed parts of the quantity being sampled.

Bags

{a) To obtain a composite sample:

(1) In quantities of five bags or less, each bag shall be sampled.

(2) In quantities of more than five bags, at least every fifth bag,

but not less than five bags, shall be sampled.

328
TESTING AGRICULTURAL AND VEGETABLE SEEDS 329

(3) For inspection purposes unopened bags shall be sampled

except under circumstances where the identity of the seed has been

preserved.

(b) To obtain individual-ba^ samples:

In obtaining samples to test for uniformity at least four bags shall

be sampled if there are less than 100 bags in the lot; seven bags if there

are from 100 to 400 bags in the lot, and 10 bags if there are over 400

bags in the lot.

Packets

In sampling seeds in packets, entire unopened packets shall be taken.

Sise of ßarafle

(a) For composite samples to test for quality, the following are

minimum weights for samples of seed to be submitted for analysis,

test, or examination :

(1) Two ounces (approximately 55 grams) of grass seed not

otherwise mentioned, white or alsike clover, or seeds not larger than

these.

(2) Five ounces (approximately 150 grams) of red or crimson

clover, alfalfa, lespedezas, ryegrasses, bromegrasses, millet, flax, rape,

or seeds of similar size.

(3) One pound of Sudan grass, sorghum, proso, hemp seed, or

seeds of similar size.

(4) Two pounds (approximately 1,000 grams) of cereals, vetches,

or seeds of similar or larger size.

(5) Vegetable seed samples shall consist of at least 400 seeds.

(i) For individual-bag samples to test for uniformity:

The size of any individual-bag sample to determine uniformity in a

lot of seed shall be not less than the quantities set out in the column

"Minimum weight for noxious-weed seed examination" for the respective kinds of seed listed in table 3.

If the sample drawn is larger than desired it shall be thoroughly

mixed before it is divided to the desired size.

Forwarding and Receipt of Ofßcial Samples

Before being forwarded for analysis, test, or examination the containers of official samples shall be properly sealed and identified. The

containers of official samples shall be initialed and dated, and the

sample shall be weighed by the person who breaks the seals.

ANALYSIS OF THE SEED

The standard analysis and test for germination for law enforcement,

labeling, and general information as to seed quality, should determine for the sample analyzed: (1) The purity composition, including

an identification to determine the kind of seed, and, if possible from

appearance, the varietal composition; (2) the rate of occurrence of

noxious-weed seeds per unit weight; and (3) the percentage germination of the pure seed under consideration.

Obtaining the Working Sample

The working sample on which the actual analysis is made shall be

taken from the submitted sample in such a manner that it will be
330 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

representative. The sample shall be repeatedly divided to obtain the

weight to be used for the working sample. With free-flowing seed,

some form of efficient mechanical divider shall be used. With nonfree-flowing seed of a character that a mechanical divider cannot be

used, the sample shall be thoroughly mixed and placed in a pile, and

the pile shall be repeatedly divided into halves until a sample of the

desired weight remains.

Weight of Working Sample

For the detailed purity analysis, the working samples of agricultural and vegetable seeds shall be at least the weights set forth in

table 3. For those seeds not listed approximately 3,000 seeds shall

be used.

TABLE 3.—Minimum weights and approximate numbers of seeds in

iDorhing samples for purity analyses

Name of seed

AGRICULTURAL SEED

Alfalfa—Medicago sativa

Alfilaria—Erodium cicutarium

Bahia grass—Paspalum notatum

Barley—Hordeum vulgäre

Bean:

Adzuki—Phaseolus angularis

Field—Phaseolus vulgaris

Mung—Phaseolus aureus

Velvet—Stizolohium deeringianum

Beet, field and sugar—Beta vulgaris

Beggarweed, Florida—Desmodium tortuosum

Bentgrass:

Astoria—Agrostis tenuis

Creeping—Agrostis palustris

Colonial—Agrostis tenuis

Highland—Agrostis tenuis

Velvet—Agrostis canina

Bermuda grass—Cynodon dactylon

Bluegrass:

Annual—Poa annua

Bulbous—Poa bulbosa

Canada—Poa compressa

Kentucky—Poa pratensis

Nevada—Poa nevadensis

Rough—Poa trivialis

Texas—Poa arachnifera

Wood—Poa nemoralis

Minimum

weight

for

purity

analysis

Minimum

weight

for

noxiousweed

seed

examination

Grams

5

5

10

100

500

500

100

500

50

Grams

50

50

50

500

500

500

500

500

300

50

25

25

25

25

25

25

25

50

25

25

25

25

25

25

Approximate

number

of seeds

per

gram

Approximate

number

of seeds

per

ounce

I

Number

500

441

366

30

11

4

24

2

54

442

12, 048

17, 196

19, 231

20, 000

23, 810

3,940

2,636

1,020

5, 500

4,800

2,304

5,600

2,500

7,097

Number

14, 175

15, 364

10, 376

851

312

113

680

57

1,531

12, 541

341, 560

487, 521

545, 199

567, 000

675, 014

111, 699

74, 731

28, 968

155, 925

136, 080

65, 434

158, 760

71, 000

201, 200
TESTING AGRICULTURAL AND VEGETABLE SEEDS 331

TABLE 3.—Minvmwm weights and approximate nvmihers of

working samples for purity analyses—Continued

in

Name of seed

Minimum

weight

for

purity

analysis

Minimum

weight

for

noxiousweed

seed

examination

Approximate

number

of seeds

per

gram

Approximate

number

of seeds

per

ounce

AGRICULTURAL SEED—Continued

Bluestem:

Big—Andropogon furcatus *

Little—Andropogon scoparius ^

Sand—Andropogon hallii ^

Brome, mountain—Bromus marginatus

Brome, smooth—Bromus inermis _

Broomcorn—Sorghum vulgäre var. technicum

Buckwheat—Fagopyrum esculentum

Buffalo grass—Buchloë dactyloides: ^

Burs

Caryopses

Canary grass—Phalaris canariensis

Canary grass, reed—Phalaris arundinacea

Carpet grass—Axonopus affinis

Chickpea—Cicer arietinum

Clover:

Alsike—Trifolium hyhridum

Alyce—Alysicarpus vaginalis

Berseem—Trifolium alexandrinum

Bur—Medicago hispida (in bur)

Bur—Medicago hispida (out of bur) _.

Bur, spotted—Medicago arabica (in

bur)

Bur, spotted—Medicago arabica (out

of bur)

button—Medicago orbicularis

Cluster—Trifolium glomeratum

Crimson—Trifolium incarnatum

Ladino—Trifolium repens

Lappa—Trifolium lappaceum

Large hop—Trifolium procumbens

Persian—Trifolium resupinatum

Red—Trifolium pratense

Sour—Melilotus indica

Strawberry—Trifolium fragiferum

Sub—Trifàlium subterraneum

Suckling or small hop—Trifolium

dubium

Sweet : White—Melilotus alba

Yellow—Melilotus officinalis

White-—Trifolium repens

Corn:

Field—Zea mays

Pop—Zea mays var. everta

See footnotes at end of table.

Grams

10

5

10

25

5

50

50

50

2

25

2

1

500

2

5

5

50

10

50

10

10

1

10

2

2

1

2

5

5

5

25

5

5

2

500

500

Grams

50

50

50

150

50

300

300

300

50

150

50

25

500

50

50

50

300

50

300

50

50

25

50

50

50

25

50

50

50

50

150

50

50

50

50

500

500

Number

336

560

233

141

300

60

45

110

738

150

1,200

2,475

2

1,500

664

456

375

49

550

337

2,924

330

1,937

1,500

5,434

1,416

600

662

635

119

1, 948

570

570

1, 500

Number

9,542

15, 904

6, 617

4,004

8,505

1,704

1,276

3, 124

20, 959

4, 254

34, 020

70, 166

57

42, 525

18, 824

12, 928

10, 650

1, 389

15, 620

9,554

82, 895

9,356

55, 010

42, 525

154, 326

40, 144

17, 010

18, 768

18, 002

3,374

55, 226

16, 160

16, 160

42, 525

85
332 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

TABLE 3.—Minim/wm weights and approximate numbers of seeds in

working samples for purity analyses—Continued

Name of seed

Minimum

weight

for

purity

analysis

Minimum

weight

for

noxiousweed

seed

examination

Approximate

number

of seeds

per

gram

Approximate

number

of seeds

per

ounce

AGRICULTURAL SEED^—Continued

Cotton—Gossypium spp

Cowpea—Vigna sinensis

Crested dogtail—Cynosurus cristatus

Crotalaria:

Crotalaria intermedia

Crotalaria júncea

Crotalaria lanceolata

Crotalaria spectabilis

Crotalaria striata

Dallis grass—rPaspalum dilatatum

Dropseed, sand—Sporoholus cryptandrus..

Fescue:

Chewings—Festuca rubra var. commutata^

Hair—Festuca capillata

Meadow—Festuca elatior

Red—Festuca rubra

Sheep—Festuca ovina

Tall—Festuca arundinacea

Flax—Linum usitatissimum

Grama:

Blue—Bouteloua gracilis ^

Side-oats—Bouteloua curtipendula: ^

Other than caryopses

Caryopses

Guinea grass—Panicum maximum

Harding grass—Phalaris tuberosa var.

stenoptera

Hemp—Cannabis sativa

Indian grass, ye 11 ow—Sorghastrum

nutans ^

Japanese lawngrass—Zoysia japónica

Johnson grass—Sorghum halepense

Kudzu—Pueraria thunbergiana

Lespedeza:

Sericea or Chinese—Lespedeza

cuneata (L. sericea)

Common (including Kobe)—Lespedeza striata

Korean—Lespedeza stipulacea

Siberian—Lespedeza hedysaroides^

Lovegrass, weepings—Eragrostis curvula^-

Lupine :

Blue—Lupinus angustifolius

White—Lupinus albus

Yellow—Lupinus luteus

Manila grass—Zoysia matrella

Meadow foxtail—Alopecurus pratensis

Medic, black—Medicago lupulina

See footnotes at end of table.

Grams

500

500

2

10

100

10

25

10

3 2

V2

2

1

5

2

2

5

10

5

2

5

5

50

10

2

10

25

5

5

5

1

500

500

500

2

2

5

Grams

500

500

50

50

500

50

150

50

50

25

50

25

50

50

50

50

50

50

50

50

50

50

300

50

50

50

150

50

50

50

50

25

500

500

500

50

50

50

Number

8

8

1,900

207

36

375

80

215

592

11,927

],200

3,200

500

1,200

1, 167

500

178

1,977

422

1,607

2,207

750

46

364

3,012

290

81

820

750

525

820

3,282

7

7

9

Number

227

227

53, 865

5,878

1,022

10, 650

2,268

6, 106

16, 795

338, 727

34, 120

90, 720

14, 175

34, 120

33, 143

14, 175

5,046

56, 147

11,985

45, 639

62, 540

21, 300

1,304

10, 338

85, 541

8,222

2,296

23, 248

21, 263

14. 884

23; 288

93, 208

198

198

225

1,200

586

34, 020

16, 613
TESTING AGRICULTURAL AND VEGETABLE SEEDS 333

TABLE 3.—Minim/imi %oeigMs and approximate numbers of seeds in

working samples for purity analyses—Continued

Name of seed

AGRICULTURAL SEED—Continued

Millet:

Browntop—Panicum fasciculatum

Foxtail, German, Hungarian, Golden

or Siberian—Setaria itálica

Japanese—Echinochloa crusgalli var.

frumentacea

Pearl—Pennisetum glaucum

Proso—Panicum miliaceum

Molasses grass—Melinis minutiflora

Mustard:

Black—Brassica nigra

White—Brassica hirta

Napier grass—Pennisetum purpureum

Oats—Avena sativa and A. hyzantina

Oatgrass, tall meadow—Arrhenatherum

elatius

Orchard grass—Dactylis glomerata

Panic grass, blue—Panicum antidotale

Peanut—Avachis hypogaea

Peas, field—Pisum sativum var. arvense.^.

Rape :

Annual—Brassica napus var. annua..

Bird—Brassica campestris

Turnip—Brassica campestris vars

Winter—Brassica napus var. biennis-.

Redtop—Agrostis alba

Rescue grass—Bromus catharticus

Rhodes grass—Chloris gayana

Rice—Oryza sativa

Ricegrass; Indian—Oryzopsis hymenoides. _

Rough pea—Lathyrus hirsutus

Rye—Sécale céréale

Ryegrass:

Italian—Lolium multiflorum

Perennial—Lolium perenne

Sainfoin—Onobrychis viciaefolia

Sesame—Sesamum orientale

Sesbania—Sesbania exáltala

Smilo—Oryzopsis miliacea

Sorghum :

(Grain and Sweet)—Sorghum vulgäre.

Soybean—Glycine max

Sudan grass—Sorghum vulgäre var. sudanense

Sunflower (Cult.)—Helianthus annuus

Sweet vernal grass—Anthoxanthum odoratum

Switch grass—Panicum virgatum

Timothy—Phleum pratense

957116—52 23

Minimum

weight

for

purity

analvsis

Grams

10

10

25

25

1

5

25

5

100

10

2

2

500

500

10

10

10

10

'A

25

1

100

10

100

100

5

5

50

10

25

2

50

500

25

100

2

5

2

Minimum

weight

for

noxiousweed

seed

examination

Grams

50

50

50

150

150

25

50

150

50

500

50

50

50

500

500

50

50

50

50

25

150

25

500

50

500

500

50

50

300

^0

150

50

300

500

150

500

50

50

50

Approximate

number

of seeds

per

gram

Numher

303

470

320

194

180

15, 000

1,256

162

28

330

1,441

1,448

1-3

4

346

425

536

230

11, 000

144

4, 724

66

308

39

40

500

500

50

360

105

2,008

50-55

6-13

120

Approximate

number

of seeds

per

ounce

Number

8,590

13, 325

9,072

5,500

5, 103

425, 250

35, 608

4, 593

1,600

814

2,500

794

9,356

40, 852

41, 123

ÍÍ3

9,809

12, 049

15, 196

6,521

311, 850

4,089

133, 925

1,871

8,747

1, 095

1, 134

14, 175

14, 175

1,418

10, 206

2, 982

57, 027

' 1,418-

. 1, 559

175-435

3, 402

45, 360

23, 117

70, 875
334 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

TABLE 3.—MinhTiuon toeights and approximate numbers of seeds in

iDorking samples for purity analyses—Continued

Name of seed

Minimum

weight

for

purity

analysis

Minimum

weight

for

noxiousweed

seed

examination

Approximate

number

of seeds

per

gram

Approximate

number

of seeds

per

ounce

AGRICULTURAL SEED—Continued

Tobacco—Nicotiana tabacum

Trefoil, big—Lotus uliginosus

Trefoil, birdsfoot—Lotus corniculatus

Vasey grass—Paspalum urvillei

Velvet-grass—Holcus lanatus

Vetch:

Common—Vicia sativa

Hairy—Vicia villosa

Hungarian—Vicia pannonica

Monantha—Vicia articulata (V. monantha)

Narrowleaf—Vicia angustifolia

Purple—Vicia atropurpúrea

Woollypod—Vicia dasycarpa _ _

Wheat: Common, spelt, emmer, durum,

club, Polish—Triticum spp

Wheatgrass:

Crested, fairway—Agropyron cristaturn

Crested, standard—Agropyron cristatum

Slender—Agropyron trachycaulum

Western—Agropyron smithii

Wild-rye, Canada—Elymus canadensis

VEGETABLE SEED

Artichoke—Cynara scolymus

Asparagus—Asparagus officinalis

Bean :

Asparagus—Vigna sesquipedalis

Garden—Phaseolus vulgaris

Horse or broad—Vicia ¡aha

Lima—Phaseolus lunatus var. macrocarpus

Runner—:Phaseolus coccineus

Beet, mangel—Beta vulgaris

Broccoli—Brassica olerácea var. hotrytis^-

Brussels sprouts—Brassica olerácea var.

gemmifera

Cabbage—Brassica olerácea var. capitata^

Cardoon—Cynara cardunculus

Carrot—Daucus carota

Cauliflower—Brassica olerácea var. botrytis

Celeriac—Apium graveolens var. rapaceum

Celery—Apium graveolens var. dulce

Chi cory—Cichorium intybus

Citron—Citrullus vulgaris ,

Collards—Brassica olerácea var. acephala.

Corn, sweet—Zea mays

Grams

u

2

2

2

1

100

100

100

100

50

100

100

100

10

10

10

10

100

100

100

500

500

500

500

50

10

Grams

25

50

50

50

25

500

500

500

500

300

500

500

500

50

50

50

50

50

500

500

500

500

500

500

500

300

50

10 50

10 50

100 500

5 50

10 50

1 25

1 25

5 50

500 500

10 50

500 500

Number

15, 625

1,944

814

970

3, 359

19

36

24

Number

442, 969

55, 209

23, 117

27, 548

95, 060

539

1,021

680

60

22

25

25

1,701

624

709

709

714 20, 242

425 12, 049

340 9,639

235 6, 662

261 7,412

24 680

25 709

8 227

4 113

2 57,

58 1, 644

315 8, 930

315 8,930

315 8, 930

826 23,417

315 8,930

2,521 71, 470

2,521 71, 470

940 26, 649

11 312

315 8,930
TESTING AGRICULTURAL AND VEGETABLE SEEDS 335

TABLE 3.—Minimuni weights and afj)roximate numhers of seeds in

working samples for furity analyses—Continued

Approximate

xr^,^^ ^t ^ j wtJiKiit ,-^„^ iiuiiiuer number Name of seed f^^ noxious- ^^ ^^^^„ ^^ ^^^^^

per

ounce

VEGETABLE SEED—Continued

Cornsalad (Fetticus)—Valerianella locusta

var. olitoria

Cowpea—Vigna sinensis

Cress:

Garden—Lepidium sativum

Water—Rorippa nasturtium-aquaticum

Cucumber—Cucumis sativus

Dandelion—Taraxacum officinale

Eggplant—Solanum melongena var, esculentum

Endive—Cichorium endivia

Kale ^—Brassica olerácea var. acephala

Kohlrabi—Brassica olerácea var. gongylodes

Leek—Allium porrum

Lettuce—Lactuca sativa

Muskmelon—Cucumis melo

Mustard:

India—Brassica júncea

Spinach—Brassica perviridis

Okra—Hibiscus esculentus

Onion—Allium cepa

Pakchoi—Brassica chinensis

Parsley—Petroselinum hortense

Parsnip—Pastinaca sativa

Peas, garden—Pisum sativum

Pepper—Capsicum spp _„

Pe-tsai (Chinese cabbage)—Brassica pekinensis

Pumpkin—Cucúrbita pepo

Radish—Raphanus sativus

Rhubarb—Rheum rhaponticum

Rutabaga—Brassica napus var, napobrassica

Salsify— Tragopogón porrifolius

Sorrel—Rumex acetosa

Soybean—Glycine max

Spinach:

Common—Spinacia olerácea

New Zealand—Tetragonia expansa^ _

Squash—Cucúrbita moschatasiná C. maxima I

Swiss chard—Beta vulgaris var. cicla-^^^^

Tomato :

Common—Lycopersicon esculentum^ _

Husk—Physalis pubescens

Turnip—Brassica rapa

Watermelon—Citrullus vulgaris

See footnotes at end of table.

MiniMinimum

mum

weight

for

Approximate

weight number

for

purity

noxiousweed of seeds

per

analysis examinationgram

Grams Grams Number

10 50 380

500 500 8

5 50 424

1 25 5, 172

100 500 38

2 50 1,240

10 50 228

5 50 940

10 50 315

10 50 315

10 50 396

5 50 888

100 500 45

5 50 624

5 50 536

100 500 19

10 50 341

5 50 633

5 50 648

10 50 429

500 500 3

25 150 167

5 50 633

500 500 4

50 300 75

50 300 60

10 50 428

50 300 66

2 50 1,079

500 500 6-13

25 150 100

100 500 13

500 500 14

50 300 58

5 50 405

2 50 1, 240

10 50 536

500 500 11

Number

10, 773

227

12, 020

146, 626

1, 077

35, 154

6,464

26, 649

8,930

8,930

11,227

25, 175

1, 276

17, 690

15, 196

539

9, 667

17, 946

18, 371

12, 162

85

4,734

17, 946

113

2, 126

1,701

12, 134

1,871

30, 590

175-435

2,835

369

397

1, 644

11,482

35, 154

15, 196

312
336 AGRICULTURE HANDBOOK NO. 3Ô, tJ. S. DEPT. OF AGRICULTURE

TABLE 3.—Minimimi weights and approximate nmniers of seeds in

working samples for purity analyses—Continued

Name of seed

Minimum

weight

for

purity

analysis

Minimum

weight

for

noxiousweed

seed

examination

Approximate

number

of seeds

per

gram

Approximate

number

of seeds

per

ounce

HERBS

Dill—Á.7i6thuTíi grciveolens

Grams

5

25

Grams

50

150

50

Number

800

121

1,750

Number

22, 720

Sage—Salvia ojfficinalis _ _ _ 3,436

Savory—Satureja hovteusis 2 49, 700

TENTATIVE METHODS

Wheatgrass:

Hairy intermediate—Agropyron trirhrnohorum 10

10

10

50

50

50

Intermediate—A gr op y ron intermenPfîll—Anrnryuron elonoatuîïi

1 Pure seed unit consists of naked caryopsis, or spikelet or floret with at least

1 caryopsis.

2 Pure seed unit consists of bur, floret, or caryopsis.

3 If the purity separation of Dallis grass yields less than 400 seeds a duplicate

analvsis shall be made and the results shall be calculated on the basis of 4 grams.

4 Pure seed unit consists of spike, spikelet, floret with a caryopsis, or free

caryopsis. Ö Includes the kales which are varieties of Brassica napus.

The weight of the working sample in mixtures shall be determined

by the kind (or group of kinds of seeds of similar size) which comprises the major proportion of the sample. When there are two or

more general weights of seed (based on the weight of the sample m

table 3), each present to about the same extent, the analyst will use his

judgment in deciding upon the kind or group which will determine

the sample weight. The weight of samples for noxious-weed seed

examinations in mixtures shall be that given in table 3 for the kind of

seed used to determine the weight of the working sample m the

mixture.

Separation

The working sample shall be weighed in grams to four significant

figures, and shall then be separated into four parts, as follows: (1)

Kind, variety, or type to be considered pure seed ; (2) other crop seed ;

(3) weed seed; and (4) inert matter.

Each of these four component parts shall be weighed in grams to

the same number of decimal places as the working sample, and the

percentage by weight of each part (based on the sum of the weights

of the component parts and not on the original weight) shall be determined, except that the pure seed need not be weighed when the minimum working sample is 500 grams ; the inert matter, other crop seeds,

and weed seeds shall be weighed and their percentages calculated on

the basis of the original weight and the pure seed percentage shall be

determined by subtracting the sum of the percentages of inert matter,
TESTING AGRICULTURAL AND VEGETABLE SEEDS 337

other crop seeds, and weed seeds from 100 percent. The size of the

working sample for any kind of seed shall not be changed from that

prescribed under the heading, "Obtaining the Working Sample."

The sum of the weights of the component parts shall be compared with

the original weight of the Avorking sample as a check against loss of

material or other error. In the case of other crop seed and weed seed,

the seeds of each species shall be separated where possible, and the

number or the weight of each kind shall be determined. The separation of the seed of the kind, variety, or type considered pure seed

must be on such a basis that the separation can be made definitely by

seed characteristics, except that when the sample contains two or more

similar kinds of seeds the separation of which in the entire working

sample would be very difficult, it is permissible to separate and weigh

the similar seeds as a group. From this mixture at least 400 seeds are

to be taken indiscriminately, and the separation made on this portion.

The proportion of each kind is then determined by weight or if the

seeds are of similar weight the proportion may be determined by

count, and from this the percentage in the entire sample is calculated.

With reference to classification of crop seeds or fragments thereof,

applicable methods of determination may include visual examination,

use of reflected light, or specific gravity. This has reference particularly to insect-damaged, broken or diseased seeds, or sterile grass

glumes.

Kind^ Variety^ or Type Considered Pijure Seed

The pure seed shall include: (a) All seeds of each kind, variety, or

type under consideration present in excess of 5 percent of the whole,

whether shriveled, cracked, or otherwise injured, and (b) pieces of

such seeds that are larger than one-half of the original size, whether

broken, insect-damaged, or diseased : Provided^ That seeds of legumes

and crucifers with the seed coat entirely removed shall be classified as

inert matter and not as pure seed.

Other Crop Seed

Other crop seed shall include: {a) Seeds of plants grown as crops

(other than the kind, variety, or type included in the pure seed) each

kind, variety, or type of which is present in a proportion to the whole

of 5 percent or less, whether shriveled, cracked, or otherwise injured,

and (&) pieces of such seeds larger than one-half of the original size

whether broken, insect-damaged, or diseased: Provided^ That other

crop seed shall not include (1) seeds of plants recognized as weeds or

(2) seeds of legumes and crucifers with the seed coats entirely removed.

Weed Seed

Seeds, bulblets, or tubers of plants recognized as weeds by laws or

official regulations or by general usage shall be considered weed seeds :

Provided^ That undeveloped or badly injured weed seeds, including

noxious-weed seeds, as described under inert matter, shall be considered inert matter and not weed seeds. When seeds of Junous spp.,

are present and would not add more than 0.1 percent to the percentage

of weed seed, they need not be separated but may be included with

the inert matter. However, the presence of the seed shall be recorded.

Inert Matter

Inert matter shall include seedlike structures from both crop and

weed plants and other matter not seeds, as follows :
338 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

{a) Seedlike structures from crop plants: Pieces of seeds one-half

the original size or less, whether broken, insect-damaged, or diseased ;

seeds of legumes and crucifers with the seed coats entirely removed ;

empty glumes and sterile florets of grasses ; attached sterile florets of

grasses (which must be removed from the fertile florets except in bluegrasses, tall meadow oatgrass, Rhodes grass, bluestems, and gramas).

(&) Seedlike structures from weed plants : All badly injured, undeveloped, or empty structures which resemble seeds but which by visual

examination (including dissection or reflected light) can be definitely

demonstrated as having no embryo or having only a rudimentary

embryo or having an embryo that has been destroyed by a disease

organism. Included as inert matter are structures from weed plants,

as follows :

(1) Seeds of grasses with over one-half the embryo removed;

(2) "Seeds" of dodder which are fragile, ashen gray to brown in

color, and somewhat enlarged;

( 3 Ragweed seed with both the involucre and pericarp absent ;

(4) Shriveled, blackened seeds of buckhorn;

(5) Empty seeds or fruits such as occur in the sedge, buckwheat,

morning-glory, and sunflower families;

(6) Empty glumes and sterile florets of grasses ;

(7) Seeds of legumes and species of Brassica with the seed coats

entirely removed ;

(8) Bulblets of wild onion and garlic with the basal or stem end

portion removed;

(9) Seeds of Jm%(M8 spp., when not in excess of 0.1 percent.

(c) Other matter: Soil, sand, stones, chaff, stems, leaves, nematode

galls, fungus bodies (such as ergot and other sclerotia and smut balls),

and all other matter not seeds.

The above definitions shall not prohibit the separation of pure seed

and inert matter of the kinds of seeds listed below by the uniform

blowing method using a controlled pressure blower calibrated by

means of a standard reference sample. The Subcommittee on Standardized Blowing Techniques may be expected to supply standard

reference samples of the kinds of subject seeds. Kinds of subject

seeds are Kentucky bluegrass {Poa fvatensis) and Canada bluegrass

{Poa compressa).

EXAMINATIONS

Noxious-Weed Seeds

The determination of the number of seeds, bulblets, or tubers of

individual noxious weeds present per unit weight should be made

on at least the minimum quantities listed in table 3 except that if

30 or more noxious-weed seeds, bulblets, or tubers of one kind are

found in the pure seed analysis (or noxious-weed seed examination

of a like amount), the occurrence of that species in the remainder

of the bulk examined for noxious-weed seeds need not be noted.

Identification and Varietal Determination

The separation representing the kind of seed under consideration

should be examined to determine whether it conforms to the name

under which it was submitted, or for further information as to varietal

composition. If such identification is not possible from seed characters or if it is not attempted, such fact should be recorded and clearly

reported or identification may be based on the seedling, growing plant,
TESTING AGRICULTURAL AND VEGETABLE SEEDS 339

or mature plant characteristics according to such authentic information as is avaihible. If a growing test for this purpose is planned,

this fact should be reported.

Origin

The presence of incidental weed seeds, foreign matter, or the existence of any other circumstances shall be considered in determining

the origin of seed.

Fluorescence Test on Ryegrass

A fluorescence test shall be made on all samples of ryegrass for which

the proportion of perennial ryegrass {Loliufm perenne) and Italian

ryegrass (Z. multijlorum) is to be determined. The seedlings shall

be grown on filter paper and the number of fluorescent seedlings

determined under the ultraviolet light at the end of the germination

period. The percentages of pure seed, fluorescence, nonfluorescence,

germination, and dead seed shall be determined and the results shall

be subjected to the following formula to calculate the proportion of

the two kinds of ryegrass present in a sample :

. _ 1.0526 X % nonfluorescence X % pure ryegrass

% perennial ryegrass= % fluorescence + % nonfluorescence

Example :

Kyegrass = 98.50% ; fluorescence = 16.5% ; nonfluorescence = 73.5%.

^ . ^.. ^. . 1.0526XY3.5%X98.50% o. ^-^

Substituting, we have, ^-^' — =84.67%.

A nomograph may be used in converting results of fluorescence

tests to pure seed in lieu of calculating the results from the above

formula.

USE OF NOMOGRAPH FOR DETERMINING PURE SEED OF RYEGRASS FROM

FLUORESCENCE TESTS

(1) Enter % nonfluorescence on Scale 2. Read off value on Scale

1 at this point. If the % germination is equal to or less than this

value on Scale 1, all the pure ryegrass is perennial.

(2) If the germination is greater than this value on Scale 1, ¡proceed as follows :

Join % nonfluorescence on Scale 2 with % pure ryegrass on

Scale 4.

Prick off intersection on Scale 3.

Join % germination on Scale 1 and prick-off point on Scale 3 and

project to cut Scale 4.

Eead on Scale 4 the percentage of pure perennial ryegrass.

Example I

Pure ryegrass 98% ; nonfluorescence 80% ; germination 84%.

(1) Enter 80 on Scale 2. Corresponding value on Scale 1 is

84.2. Since germination is 84, that is, less than this value, all the

pure ryegrass is perennial.

Example II

Pure ryegrass 95%; nonfluorescence 75%; germination 84%.

(1) Enter 75 on Scale 2. Corresponding value on Scale 1 is 79

(nearly). Since germination is 84, that is, greater than this value,

proceed as follows :
340 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

CHART FOR DETERMINING PERCENTAGE

OF PURE PERENNIAL RYEGRASS

ON THE BASIS OF THE FLUORESCENCE TEST.

_100

(2) Join 75 on Scale 2 and 95 on Scale 4. Read off 79.4 on

Scales.

(3) Join 84 on Scale 1 and 79.4 on Scale 3 and project to cut

Scale 4 at 89.4.

(4) Percent pure perennial ryegrass is 89.4.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 341

In determining the percentage of yellow blossom biennial sweetclover in a mixture of yellow and white blossom biennial sweetclover,

5 grams of seed shall be examined to determine the percentage of

mottled seed. The percentage of mottled seed shall be multiplied by

4 and the product shall be construed as representing the percentage

of yellow blossom sweetclover.

GERMINATION TESTS

Source of Seeds for Germination

(1) When hoth purity and germination tests are required:

Seeds for germination shall be taken from the separation of the

kind, variety, or type considered pure seed and shall be counted without discrimination as to size or appearance.

(2) When only a germination test is required:

If only a germination test is required and the pure seed is estimated

or determined to be at least 98 percent, the pure seed for the germination test may be taken indiscriminately from a representative portion

of the bulk.

If only a germination test is required and the pure seed is found

to be less than 98 percent, the pure seed shall be taken indiscriminately

from a pure seed separation made according to the provisions of these

rules which govern the separation of the kind, variety, or type considered pure seed, except that the crop seeds, inert matter, and weed

seeds need not be separated.

Reports of Germination

The exact pure seed percentage or the fact that it was estimated to

be 98 percent or more shall be recorded and included in any report

of germination.

Number of Seeds for Germination

At least 400 seeds shall be tested for germination. These seeds

shall be tested in replicate tests of 100 seeds or less, except that in

mixtures 200 seeds of those kinds present to the extent of 15 percent

or less may be used in which case an additional 2 percent is to be added

to the regular germination tolerances.

Retests

Eetests shall be made if there is a diiïerence of 10 percent between

any two of the separate 100 seeds tested when the average of the tests

is 80 percent or above ; and if there is a difference of 15 percent when

the average is below 80 percent; otherwise, the average of the tests

shall be considered the result of the test.

Seed Germination

In seed laboratory practice, germination is defined as the emergence

and development from the seed embryo of those essential structures

which, for the kind of seed in question (table 4), are indicative of the

ability to produce a normal plant under favorable conditions.

Hard Seeds

Seeds which remain hard at the end of the prescribed test because

they have not absorbed water owing to an impermeable seed coat, are

to be counted as "hard seed." Kinds of seed known and recognized

as containing hard seed are indicated in table 4 (footnote 5).
342 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Extension of Time on Legumes^ Okra^ and Asparagiùs for Swollen

/Seeds and Seeds Which Have Just Started to Germinate

If at the end of the germination period provided for in table 4 there

are still present swollen seeds or seeds which have just started to

germinate, all other seeds and seedlings shall be removed and the test

continued for 5 additional days and the normal seedlings included in

the percentage of germination.

Evaluation of Seedlings

The photographs of normal and abnormal seedlings prepared by

the Federal Seed Laboratory, Beltsville, Md., as approved at present

or in the future by the Association of Official Seed Analysts, shall

be accepted as standard guides for classification of seedlings. The

negative numbers shall be listed in the column headed "Remarks"

following the respective kinds of seed. During the progress of the

test, seeds which are obviously dead and moldy and which may be

a source of contamination of healthy seeds should be removed at each

count and the number of such dead seeds should be recorded. Soil

and/or sand tests are to be used as a standard guide for the evaluation

of germination tests made on approved artificial media in determining

the classification of questionable seedlings. This is intended to provide a method of checking the reliability of tests made on artificial

substrata when there may be doubt as to the proper evaluation of

such tests and it is not intended to mean that all samples are to be

tested in sand or soil.

Moisture and Aeration

The substratum must be moist enough at all times to supply the

needed moisture to the seeds but there is danger that in supplying

excessive moisture the aeration of seeds will be restricted. Except

as provided for those kinds of seeds requiring high moisture levels

of the germination media, the substrata should never be so wet that

a film of water is formed around the seeds. For most kinds of seeds

blotters or other paper substrata should not be so wet that, by pressing,

a film of water forms around the finger. The following formula

should be used as a basic guide in the preparation of sand for germination tests :

118.29 cc. (1 gill) sand ^^^ ^_^ Q_The number of cc. of water to

Its weight in grams " ' add to each 100 grams of sand.

The amount of water provided by this formula may have to be modified slightly, depending on the kind of seed being tested. For example,

slightly more moisture should be added when the larger seeds are

to be tested. In preparing soil tests w^ater should be added until the

consistency of the soil is such that a ball is formed by squeezing in

the palm of the hand, but the ball will break freely when pressed

between two fingers. After the soil has been wetted it should be

rubbed through a sieve and put in the containers for the test, without

packing. The addition of water subsequent to placing the seed in

test will depend on the evaporation from the substrata in the germination chambers. Since the rate of evaporation will depend on the

relative humidity of the air, it is desirable to keep water in the germination chambers or to provide other means of supplying a relative

humidity of approximately 95 percent. Germination tests should be

observed at frequent intervals to insure adequate moisture in the

substrata at all times.
TABLE 4.—Testing procedures for laboratory germination and hard seed content of specified kinds of seed samples

Name of seed

AGRICULTURAL SEED

Alfalfa—Medicago sativa

Alfilaria—Erodium cicutarium

Bahia grass—Paspalum notatum

Barley—Hordeum vulgäre

Bean:

Adzuki—Phaseolus angularis _ _

Field—Phaseolus vulgaris

Mung—Phaseolus aureus

Velvet—Stizolobium deeringianum

Beet, field, sugar—Beta vulgaris

Substrata ^

B, S

B

P

T, S

R, S

R, S

R, S

R, C, S

B

Temper- First Final

ature 2 count 3 count

° C. Days Days

20 4 '7

20-30 3 14

30-35 3 21

20 4 7

20-30 4 5 10

20-30 5 58

20-30 3 n

20-30 3 5 14

20-30 3 14

Remarks ^

Photographs 2481, 2486.

Clip seeds.

Light; remove all glumes with aid of sharp

scalpel; fresh and dormant seed lightly scratch

surface of caryopsis and use KNO?,.^

Fresh and dormant seed prechill 5 days at 5° or

10° CJ

Watch for abnormals; open the cotyledons if

plumule is not visible. Abnormal seedlings

include those without a terminal bud or growdng

point of the stem ("baldheads") and seedlings

with both primary leaves absent even though

the terminal bud or growing point is present

("snakeheads"). Such abnormal seedlings are

not to be included in determining the percentage

of germination. Photographs 1834, 1835, 1846,

1854, 1855.

Soak in water 2 hours before testing, using at least

250 cc. water per 100 "seeds''; w^ash in running

water after soaking and blot surface dry.

Samples producing darkened radicles should

be retested in sand or soil or by washing in

running water for 3 hours and testing on 0.3-

inch-thick "Kimpak" containing 85 cc. w^ater

per 9" X9'' square on top of moistened blotters,

keeping seed covered with slightly moist

blotters.

See footnotes at end of table.

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TABLE 4.—Testing procedures for laboratory germination and hard seed content of specißed kinds of seed samples—Con.

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Name of seed Substrata ^ Temperature 2

First

count

Final

count Remarks ^

AGRICULTURAL SEED—Continued

Beggarweed, Florida—Desmodium tortuosurri-^.

Bentgrass:

Colonial, Astoria and Highland—Agrosti

tenais.

Creeping (seaside)—Agrostis palustris

Velvet—Agrostis canina

Bermuda grass—Cynodon dactylon

Bluegrass:

Annual—Poa annua

Bulbous—Poa bulbosa

Canada—Poa compressa

Kentucky—Poa pratensis

Nevada—Poa nevadensis

Rough—Poa trivialis

Texas—Poa arachnifera

Wood—Poa nemoralis

Bluestem :

Big—Andropogon furcatus

Little—Andropogon scoparius

Sand—Andropogon hallii

Brome:

Mountain—Promus marginatus

Smooth—Promus inermis

Broomcorn—Sorghum vulgäre var. technicum^^

Buckwheat—Fagopyrum esculentum

B

P

P

P

P

P

P, S

P

P

P

P

P

P, TS

P, TS

P, TS

P

P, TB

B, S

B, T

° C.

30

20-30

20-30

20-30

20-35

20-30

10

15-30

15-30

20-30

20-30

20-30

20-30

20-30

20-30

20-30

20-30

20-30

20-30

20-30

Days

7

7

7

7

10

10

10

7

7

7

Days

5 28

28

28

21

21

21

35

28

28

21

21

28

28

28

28

28

14

14

10

6

Light, KNOs;^ fresh seed KNO3,« 10°-30° C,

and approximately 100 foot-candles of light.

Light, KNOs.^

Do.

Light, KNOs.'^ Photograph 2518.

Light.

Prechill 1 week at 5° C.,^ KNO36 or soil.

Light, 0.1 percent KNOa;^ fresh and dormant

seed KN03,6 10''-30°C., and approximately

100 foot-candles of light.

Light, 0.1 percent KNOs.^ Prechill dormant

seeds at 10° C. for 5 days.^

Light, KNO3.«

Light.

Light, KNO3; ^ prechill fresh and dormant seed

at 5° C. for 2 weeks.^

Light.

Light, KNOo;^ prechill fresh and dormant seed

at 5° C. for 2 weeks.^

Do.

Do.

Light.

Do.
Buffalo grass—Buchloë dactyloides:

Burs

Caryopses__^__^_

Canary grass—Phalaris canariensis

Canary grass reed—Phalaris arundinacea

Carpet grass—Axonopus affinis

Chickpea—Cicer arietinum

Clover:

Alsike— Trifolium hyhridum

Alyce—Alysicarpus vaginalis

Berseem—Trifolium alexandrinum^^.

Bur—Medicago hispida

Bur, spotted—Medicago arabica

Button—Medicago orhicularis

Cluster— Trifolium glomeratum

Crimson—Trifolium incarnatum

Ladino—Trifolium repens

Lappa-— Trifolium lappaceum

Large hop—Trifolium procumhens_.

Persian—Trifolium resupinatum

Red—Trifolium pratense

See footnotes at end of table.

P, TB, TS PBPP

R,S

B,S

B,S

B,T

B,T

BB

B,S

B,S

BBB

B,S

20-357 28

20-355 14

20-30

3

7

20-30

5 21

20-35 10 21

20-303

7

20

3 , '7

35

4

5 21

20

3 57

20

4

5 14

204

5 14

204 no

204 no

20

4 57

20

3 57

20

3 57

204

5 14

20

3 57

20

4 57

Light, KNOs;^ prechill fresh and dormant seed

at 5°C.' for6 weeks and germinate 14 additional days.

Light, KNO3.6

Light; fresh and dormant seed KNOs.^

Do.

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a

temperature of 17° to 18° is most desirable.

At conclusion of 21-day test period carefully

pierce seed coat of swollen seeds with needle

or scalpel and continue test for5 days.

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a

temperature of 17° to 18° is most desirable.

Remove seeds from bur.

Do.

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a

temperature of 17° to 18° is most desirable.

Do.

Dormant seed 15° C. The germination temperature should never exceed 20° C; and a tenàperature of 17° to 18^ is most desirable. Photographs 2479, 2482.

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a

temperature of 17° to 18° is most desirable.

Do.

Do.

Do.

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a temperature of 17° to 18° is most desirable. Photographs 2483, 2484.

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TABLE 4.—Testing procedures forlaboratory germination and hard seed content of specified hinds of seed samples—Con. 00

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d

d

Name of seed Substrata ^ Temperature 2

First

count ^

Final

count

° a

20

20

Days

3

3

Days

5 14

57

20

20

20

20

4

4

4

3

5 14

5 14

57

57

20-30

20-30

20-30

4

4

4

7

7

12

20-30 5 58

20-30 10 21

20-30 4 no

20-35

15-35

7

5

21

42

Remarks *

AGRICULTURAL SEED—Continued

Clover—Continued

Sour—Melilotus indica

Strawberry—Trifolium fragiferum

Sub—Trifolium snhterraneum

Suckling (small hop)—Trifolium dubium^.

Sweet—Melilotus alha and M. officinalis-..

White—• Trifolium repens

Corn:

Field—Zea mays

Pop—Zea mays var. everta

Cotton—Gossypium spp

Cowpea—Vigna sinensis

Crested dogtail—Cynosurus cristatus

Crotalaria—Crotalaria intermedia, C. júncea

C. lanceolata, C. spectabilis, and C. striata.

Dallis grass—Paspalum dilatatum

Dropseed, sand—Sporoholus cryptandrus

B

B

B

B

B, S

B, S

R, S

R, S

R, S

R, S

P

B, S

P

P

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a

temperature of 17° to 18° is most desirable.

Do.

Do.

Photographs 2374, 2375, 2376, 2381.

Dormant seed 15° C. The germination temperature should never exceed 20° C. and a

temperature of 17° to 18° is most desirable.

Photographs 2510, 2511, 2512, 2514.

Roll towel tests in upright position. Alternate

method: Shake seed in a closed container,

thoroughly wetting the lint. Blot off excess

moisture.

Watch for weevil injury to plumule. Photographs 1989, 1990, 2377.

Light; fresh and dormant seed prechill for 3 days

at 0° or 10° C.7

Photographs 2496, 2497.

Light; fresh and dormant seed KNO3.®

Light, KNO3; ^' dormant seed prechill at 5° C. for

4 to 8 weeks and germinate for 28 davs.^
Fescue:

Chewings—Festuca rubra var. commutata

Hair—Festuca capillata

Meadow—Festuca elatior

Red—Festuca rubra

Sheep—Festuca ovina

Tall—Festuca arundinanea

Flâx—Linum usitatissimum

Grama:

Blue—Bouteloua gracilis

Side-oats—Bouteloua curtipendula

Guinea grass—Panicum maximum

Harding grass—Phalaris tuberosa var, stenoptera

Hemp—Cannabis sativa

Indian grass, yellow—Sorghastrum nutans

Japanese lawngrass—Zoysia japónica

Johnson grass—Sorghum halepense

Kudzu—Pueraria thunbergiana

Lespedeza:

Common (Kobe)—Lespedeza striata

Korean—Lespedeza stipulacea

Sericea or Chinese—Lespedeza cuneata

(L. sericea).

Siberian—Lespedeza hedysaraides

Lovegrass, weeping—Eragrostis curvula

Lupine:

Blue—Lupinus angustifolius..

White—Lupinus alhus

Yellow—Lupinus luteus

Manila gvsiSfi—Zoysia matrella

Meadow foxtail—Alopecurus pratensis

Medic, black—Medicago lupulina

See footnotes at end of table.

ppppp

B,S

P, TB PPPB

P, TS PPT

B,S

B

B,S

B,S

P

R,S

R,T

R,T

PP

B,S

15-25

7 21

10-25 10 28

20 30

5 14

15-25

7 21

15-257 21

20-305 14

20-30

3

7

20-30

7 28

15-307 28

20-30 10 28

10-307 28

20-30

3

7

20-30

7 28

20-35 10 28

20-357 35

20-30

5

5 14

20-357

5 14

20-355

5 14

20-3575 28

20-357

5 21

20-35

5 14

20

4

5 10

20

3

57

2075 21

20-35 10 28

20-307 14

20

4 57

Alternate method: 20°-30° C, light, and test for

28 days.

KNO3.6

Light.

Alternate method: 20°-30° C, lÍ2:ht, and test for

28 days.

Do:

Light.

Photographs 2003, 2008, 2485, 2487.

Light; fresh and dormant seed KNO3.0

Light. KNO3.6

Light.

Light; fresh and dormant seed KNO3.0

Light, KNO3; fresh and dormant seed prechill at

5° C. for2 weeks.«^

Light, KNO3.6

Light; fresh and dormant seed KNO^.^

Photograph 2494.

Light; fresh and dormant seed KNO^,^

Photographs 14535 through 14542.

Light, KNO3.«

Light.

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TABLE 4.—Testing procedures forlaboratory germination and hard seed content of specified hinds of seed samples—Con. CO

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Name of seed Substrata ^ Temperature 2

First

count 3

Final

count

20-30

20-30

Days

4

4

Days

14

10

20-30 4 10

20-30

20-30

20-30

3

3

7

7

7

21

20-30 3 7

20-30

20-30

20

3

3

5

5

10

10

20-30

20-30

20-30

20-30

20

6

7

7

5

3

14

21

28

10

58

20-30

20-30

20-30

20-30

20-30

3

3

i

5

7

10

7

7

10

Remarks ^

AGRicuLTUKAL SEED—Continued

Millet:

Browntop—Panicum fasciculatum

Foxtail, such as common, German, Hungarian, Siberian, or Golden—Setaria

itálica.

Japanese—Echinochloa crusgalli var. frumentacea.

Pearl—Pennisetum glaucum

Proso—Panicum miliaceum

Molasses grass—Melinis minutiflora

Mustard:

Black—Brassica nigra

White—Brassica hirta

Napier grass—Pennisetum purpureum

Oats—Avena sativa and A. byzantina

Oatgrass, tall—Arrhenatherum elatius

Orchard grass—Dactylis glomerata

Panic grass, blue—Panicum antidotale

Peanut—Arachis hypogaea

Peas, field—Pisum sativum var. arvense

Rape:

Annual—Brassica napus var. annua

Bird—Brassica campestris

Turnip—Brassica campestris vars

Winter—Brassica napus var. hiennis

Redtop—Agrostis alba

B

B

B

B

B

P

P

B

T, S

P

P, S

P, TS

R, S

R, S

B

P

B

B

TB, P

Light.

Light; fresh and dormant seed KNOs,^ and prechill at 10° C. for 3 days.^

Light,

Fresh and dormant seed prechill for 5 days at

5° C. or 10° C. and conclude test on seventh

day.7 Photographs 2407, 2408, 2524 through

2527.

Light.

Light; germination more rapid on soil.

Light.

Remove shells.

Photographs 2503, 2506, 14543 through 14547.

Light, fresh and dormant seed KNOa.^

Light.
Rescue grass—Bromus catharticus

Rhodes grass—Chloris gayana

Rice—Oryza sativa

gRicegrass, Indian—Oryzopsis hymenoides

gRough pea—Lathyrus hirsutus. i Rye—Sécale céréale

cu

toI Rj^egrass: ^ Italian—Lolium multiflorum

Perennial—Lolium perenne

Sainfoin—Onobrychis viciaefolia.

Sesame—Sesamum orientale

Sesbania—Seshania exáltala

Smilo—Oryzopsis miliacea

Sorghum :

Grain and Sweet (sorgo)—Sorghum vulgäre

Soybean—Glycine max

Sudan grass—Sorghum vulgäre var. sudanense.

Sunflower (Cult.)—Helianthus annuus

Sweet vernalgrass—Anthoxanthum odoratum^^.

Switch grass—Panicum virgatum

Timothy—Phleum pratense

Tobacco—Nicotiana tabacum

Trefoil:

Big—Lotus uliginosus

Birdsfoot—L. corniculatus

Vasey grass—Paspalum urvillei

Velvetgrass—Holcus lanatus^

See footnotes at end of table.

P,S

p

B,T

PT

T,S

P, TB

P, TB BPTP

B,S

R,S

B,S

T,B

P

P, TS

P, TB

P, TB BBPP

10-30

20-30

20-30

15

7657

28

14

14

42

20

20

74

5 147

20-30

5 14

20-30

5 14

20-30

20-30

20-30

20-30

4357

5 146

^7

42

20-304 10

20-30

20-30

20-30

20-30

15-30

543?

58

107

14

28

20-30

5 10

20-30

7 14

20

20

20-35

20-30

3376

57

21

14

Light; fresh and dormant seed in soil at 15° C.

Light.

Prechill fresh and dormant seed at 3° C. for4

weeks and test for 21 additional days.^

Prechill fresh and dormant seed at 5° or 10° C.

for5 days.7 Photographs 2403, 2406, 2528

through 2531.

KNOa;^ light; for fluorescence test the seed

should be germinated on filter paper; fresh

and dormant seed KNOg,« 10°-30° C. and approximately 100 foot-candles of light.

Light; for fluorescence test the seed should be

germinated on filter paper.

Light; fresh and dormant seed prechill at 5° C.

for2 weeks.^

Fresh and dormant seed prechill at 5° or 10° C.

for5 days.7 Photographs 2413 through 2416.

Photographs 2371, 2372, 2378.

Photographs 2449 through 2452.

Light.

Light, KNO3;^ fresh and dormant seed prechill

at 5° C. for2 weeks.7

Light; fresh and dormant seed KNO3.6 Photograph 2399.

Light.

Light; fresh and dormant seed KNO3.0

Li.^ht.

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TABLE 4.—Testing j>rocedures for laboratory germination and hard seed content of specified hinds of seed samples—^Con. CO

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Name of seed Substrata ^ Temperature 2

First

count ^

Final

count

° C.

20

Days

5

Days

5 10

20

20

20

20

20

20

5

5

5

5

5

5

5 14

5 10

MO

5 14

MO

5 14

20 4 7

20 4 10

20-30 5 14

20-30

20-30

5

7

14

35

15-30 7 21

20-30

20-30

7

7

21

5 21

20-30 5 58

Remarks ^

AGRICULTURAL SEED—continued

Vetch:

Common—Vicia sativa

Hairy—Vicia villosa

Hungarian—Vicia pannonica

Monantha—Vicia articúlala (V. monanthá).

Narrowleaf—Vicia angustifolia

Purple—Vicia atropurpúrea

Woollypod—Vicia dasycarpa

Wheat:

Common, club, Polish (including spelt and

emmer)—Triticum spp.

Durum—Triticum durum

Wheatgrass:

Crested (Fairway and Standard)— Agropyron cristatum.

Slender—Agropyron trachycaulum

W^estern—Agropyron smithii

Wild-rye, Canada—Elymus canadensis

VEGETABLE SEED

Artichoke—Cynara scolymus

Asparagus—Asparagus officinalis

Bean :

Asparagus—Vigna sesquipedalis

T

T

T

T

T

T

T, S

T, S

P, TB

P, TB

P

T

T

R, S

Test questionable samples with stubby roots in

soil.

Photographs 2453 through 2457.

Fresh and dormant seed prechill at 5° or 10°C. for

5 days.' Photographs 2507, 2520 through

2522.

Fresh and dormant seed prechill at 5° or 10° C.

for 5 days.7

Light; fresh and dormant seed KNOs,^ and 5° or

10° C. for 7 days.7

Light.

Light; fresh and dormant seed KNO3,* or soil and

15°-30° C.

Light; fresh and dormant seed prechill at 5° C.

for 2 weeks.7

Watch for weevil injury to plumule.
Garden

—Phaseolus vulgaris.. R,

S

Horse or broad—Vicia faba^

Lima—Phaseolus lunatus var. macrocarpus.

Runner—Phaseolus coccineus.

Beet—Beta vulgaris

Broccoli—Brassica olerácea var. hotrytis

Brussels sprouts—Brassica olerácea var. gemmifera.

Cabbage—Brassica olerácea var. capitata

Cardoon—Cynara cardunculus

Carrot—Daucus carota

See footnotes at end of table.

s,c

R, S,C

R,S

B

B,P

B,P

B,P

TB

20-30

20

20-30

20-30

20-30

20-30

20-30

20-30

20-30

20-30

58

14

595 9

14

10

10

10

21

28

Watch for abnormals; open the cotyledons if

plumule is not visible. Abnormal seedlings in

beans include seedlings withouta terminal bud

or growing point of the stem (''baldheads")

and seedlings with both primary leaves absent

even though the terminal bud or growing point

is present ("snakeheads"). Such abnormal

seedlings are not to be included in determining

the percentage of germination. Photographs

1834, 1835, 1846, 1854, 1855.

Prechill fresh and dormant seed3 days at 10° C.^

The germination temperature should never

exceed 20° C. anda temperature of 17° to 18° C.

is most desirable.

Watch for abnormals; open the cotyledons if

plumule is not visible. Abnormal seedlings in

beans include seedlings withouta terminal bud

or growing point of the stem (*'baldheads")

and seedlings with both primary leaves absent

even though the terminal bud or growing point

is present ("snakeheads"). Such abnormal

seedlings are not to be included in determining

the percentage of germination. Photographs

2380, 2400, 2401.

Soak in water2 hours before testing, using at

least 250 co. water per 100 "seeds"; wash in

running water after soaking and blot surface

dry. Samples producing darkened radicles

should be retested in sand or soil or by washing

in running water for3 hours and testing on

0.3-inch-thick "Kimpak" keeping seed covered

with slightly moist blotters.

Dormant seed hght, KNOj,^ prechill at 5° or

10° C. for3 davs.7

Do.

Do.

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TABLE 4.—Testing procedures for laboratory germination and hard seed content of specified hinds of seed samples—Con.

Name of seed Substrata ^ Temperature 2

First

count 3

Final

count

° C.

20-30

Days

3

Days

10

20-30 10 21

20-30 10 21

20-30 5 14

20-30

20-30

7

3

14

10

20-30

20

4

7

7

28

20-30 5 58

•^ 20

20-30

20-30

4

4

3

10

14

7

20-30 7 21

20-30 7 14

Remarks *

Or

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VEGETABLE SEED—Continued

Cauliflower—Brassica olerácea var. hotrytis

Celeriac—Apium graveolens var. rapaceum

Celery—Apium graveolens var. dulce

Chicory—Cichorium intyhus

Citron—Citrullus vulgaris

Collards—Brassica olerácea var. acephala

Corn, sweet—Zea mays

Cornsalad (Fetticus)—Valerianella locusta var

olitoria,

Cowpea—Vigna sinensis

Cress:

Garden—Lepidium sativum

Water—Rorippa nasturtium-aquaticum

Cucumber—Cucumis sativus

Dandelion—Taraxacum officinale

Eggplant—Solanum melongenaysir. esculentum—

B, P

P, TB

P, TB

P. TS

T

B, P

R, S

B

R, S

B, P

P

T, S, B

P, TB

TB

Dormant seed light, KNOs,^ prechill at 5° or

10° C. for 3 days.7

Light. If injury to roots is apparent use Whatman's No. 2 filter paper or equivalent as substratum.

Light; fresh and dormant seed KNOs,^ and prechill at 10° C. for 3 days.^ If injury to roots

is apparent use Whatman's No. 2 filter paper

or equivalent as substratum.

Light; KNO36 or soil. If injury to roots is apparent use Whatman's No. 2 filter paper or

equivalent as substratum. Photograph 2504.

Soak 6 hours; test dormant seed at 30° C.

Dormant seed light, KNOs,^ prechill at 5° or

10° C. for 3 days.7

Photographs 2510, 2511, 2512, 2514.

Fresh and dormant seed 10° or 15° C.

Watch for weevil injury to plumule. Photographs

1989, 1990, 2377.

Dormant seed 15° C. and light.

Light.

Keep substrata somewhat drier than they are

maintained for the average kind of seed.

Light. If injury to roots is apparent use Whatman's No. 2 filter paper or equivalent as

substratum.

Alternate method: Test between blotters with

raised covers by folding up edges of bottom to

form a good support for top or cover, so top

will not make contact with seed.
Endive—Cichorium endivia.

Kale—Brassica olerácea var. acephala

Kohlrabi—Brassica olerácea var. gongylodes

Leek—Allium porrum

Lettuce—Lactuca sativa

Muskmelon—Cucumis melo

Mustard:

India—Brassica júncea

Spinach—Brassica perviridis

Okra—Hibiscus esculentus

Onion—Allium cepa

Pakchoi—Brassica chinensis

Parsley—Petroselinum hortense

Parsnip—Pastinaca sativa

Peas, garden—Pisum sativum

Pepper—Capsicum spp

Pe-tsai (Chinese cabbage)—Brassica pekinensis

Pumpkin-—Cucúrbita pepo

Padish—Raphanus sativus

Rhubarb—Rheum rhaponticum

Rutabaga^—Brassica napus var. napobrassica. _.

See footnotes at end of table.

P, TS

B, P

B, P

B

P

B, T, S

B

R

B, S

B

B

B

R, S

TB

B

T, S

TS

B

20-30 5 14

20-30 3 10

20-30

20

20

3

6

None

10

14

7

20-30 4 10

20-30 3 7

20-30

20-30

20

3

4

6

7

521

10

20-30

20-30

20-30

20

20-30

3

11

6

5

6

7

28

28

58

14

20-30

20-30

3

4

7

7

20 4 6

20-30

20-30

7

3

21

14

Light, KNOa,^ or soil; dormant seed add about

Ys inch of tap water at beginning of test;

remove the excess water after 24 hours. If

injury to roots is apparent use Whatman's

No. 2 filter paper or equivalent as substratum.

Dormant seed light, KNOa,^ prechill at 5° or

10° C. for 3 days.7

Do.

Light for at least }^ hour; fresh and dormant seed

prechill at 10° or 15° C. 3 days; watch for

sprouts with both spotted cotyledons and

stubby radicles.7 Photographs 2417, 2418.

Keep substrata somewhat drier than they are

maintained for the average kind of seed.

Light; fresh and dormant seed KNOs,^ and

prechill at 10° C. for 3 days.^

In sand and soil tests extend final count to 12

days. Photographs 1962, 2253, 2254, 2328,

2330, 2340, 2341, 2469.

Photographs 2492, 2498, 2499, 2500.

Alternate method: Test between blotters with

raised covers by folding up edges of bottom to

form a good support for top or cover, so top

will not make contact with seed.

Keep substrata somewhat drier than they are

maintained for the average kind of seed.

Classify as abnormal all seedlings with 50 percent

or more of the area of the cotyledons covered

with spots or darkened areas.

Light.

H3

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TABLE 4.—Testing procedures for laboratory germination and hard seed content of specified kinds of seed samples—Con. CO

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Name of seed Substrata Temper- First Final

ature 2 count ^ count

°C. Days Days

20 5 10

20-30 3 14

20-30 5 58

10 7 21

10-30 5 28

20-30 4 7

20-30 3 14

20-30 5 14

20-30 7 28

20-30 3 7

20-30 4 14

20-30 7 21

20-30 5 14

20-30 5 21

Remarks ^

VEGETABLE SEED COUtinued

Salsify^— Tragopogón porrifolius

Sorrel—Rumex acetosa

Soybean (vegetable)—Glycine max

Spinach :

Common—Spinacia olerácea

New Zealand—Tetragonia expansa

Squash^—Cucúrbita moschata and C. maxima.

Swiss chard—Beta vulgaris var. cicla

Tomato :

Common—Lycopersicon esculentum.

TS, P

R, S

TB

TS, B

T, S

B

Husk—Physalis puhescens.

Turnip—Brassica rapa

Watermelon—Citrullus vulgaris

HERBS

Dill—Anethum graveolens

Sage—Salvia officinalis. _

Savory—Satureja hortensis

P, TB

B

T, S

B

B, S

B

Prechill fresh and dormant seed at 10° C.

days. 7

Light. Test dormant seed at 15° C.

Photographs 2371, 2372, 2378.

for 3

Keep substrata somewhat drier than they are

maintained for the average kind of seed.

Keep substrata somewhat drier than they are

maintained for the average kind of seed.

Alternate method: Remove pulp and test at

15° C. between blotters.

Keep substrata somewhat drier than they are

maintained for the average kind of seed.

Soak in water 2 hours before testing, using at

least 250 cc. water per 100 ''seeds"; wash in

running water after soaking and blot surface

dry. Samples producing darkened radicles

should be retested in sand or soil or by washing

in running water for 3 hours and testing on 0.3-

inch-thick "Kimpak", keeping seed covered with

slightly moist blotters.

Dormant seed light and KNOs.^ Alternate

method: Test between blotters with raised

covers by folding up edges of bottom to form a

good support for top or cover, so top will not

make contact with seed. Photograph 2513.

Light.

Keep substrata somewhat drier than they are

maintained for the average kind of seed.
TENTATIVE METHODS

Wheatgrass:

Hairy intermediate—Agropyron tricophorum.

Intermediate—Agropyron intermedium

Tall—Agropyron elongatum

P

P

P

20-30 5 28

20-30 5 21

20-30 5 21

Light.

Light.

Light; prechill fresh and dormant seed at 5°C. for

7 davs.^ I

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ALTERNATE METHODS

Barley—Hordeum vulgäre..

Oats—Avena spp

Rye—Sécale céréale

Wheat—Triticum spp

Redtop—Agrostis alba

Timothy—Phleum pratense

T, S

T, S

T, S

T, S

TB, P

TB, P

15 4 7

15 5 10

15 4 7

15 4 7

20-30 5 10

20-30 5 10

Light; prechill fresh and dormant seed at 10° C.

for 5 days.7

Do.

1 Substrata: B =between blotters; TB=top of blotters; T=between folded paper toweling; R=rolled towels; S=soil or sand;

TS=top of soil; P=covered petri dishes with (a) 2 layers of blotters;

or (b) 1 layer of absorbent cotton; or (c) 5 layers of paper toweling;

or (d) filter paper; or (e) %-inch layer of sand or soil ; C =creped cellulose paper wadding (0.3-inch-thick Kimpak or equivalent) covered

with a single thickness of blotter through which holes are punched

for the seeds which are pressed for about }^ their distance into the

creped paper wadding.

2 Temperature: A single numeral indicates a constant temperature. Two numerals separated by a dash indicate an alternation

of temperature; the test is held at the first temperature for approximately 16 hours and at the second temperature for approximately 8 hours per day. If tests are not subjected to alternating

temperatures over week ends and on holidays they are to be held

at the lower temperature during such time.

3 The number of days stated for the first count is ¡approximate

and a deviation of 1 to 3 days is permitted.

4 Photograph numbers identify photographs of some types of

normal and abnormal seedlings. These photographs may be purchased from The Press Service, Office of Information, U. S. Dept.

of Agriculture, Washington 25, D. C.

5 Hard seeds are often present. If at the end of the germination

period there are still present swollen seeds or seeds which have

just started to germinate all other seeds or seedlings shall be removed and the test continued for 5 additional days; the normal

seedlings produced in this period should be included in the percentage of germination.

6 A two-tenths percent solution of potassium nitrate (KNO3)

is used in moistening the substratum in all instances except for

Canada and Kentucky bluegrass. This solution is prepared by

dissolving 2 grams of KNO3 in 1,000 cc. of distilled water. A

one-tenth percent solution is prepared by dissolving 1 gram of

KNO3 in 1,000 cc. of distilled water.

^ The prechilling period is not included in the germination period

given in this table unless otherwise specified.
356 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

TOLERANCES

Application

The following tolerances shall be recognized between the percentages

or rates of occurrence found by analysis, test, or examination and percentages or rates of occurrence required or stated. Unless otherwise

provided, the tolerances shall be applied to the percentages or rates

of occurrence found. These tolerances shall be applicg^ble to Tentative

Rules as well as to the established rules. The tolerance tables included

herein are a part of these rules. The values shown in these tables were

obtained by application of the indicated formula.

Purity Percentage

In the determination of the tolerance for the percentage of the

distinguishable kind, type, or variety (pure seed), weed seeds, other

crops seeds, and inert matter, the sample shall be first considered as

made up of two parts: {a) The percentage of the component (pure

seed, weed seed, crop seed, or inert matter, as the case may be) being

considered, and (b) the difference between that percentage and 100.

The number represented by {a) is then multiplied by the number represented by (&), and the product is divided by 100. The resulting

number is then multiplied by 0.2, and the resulting product added to

0.2 or 0.6 as indicated in the following formula :

Pure seed tolerance = 0.6 +1 ' 1

Weed seeds, other crop seeds, and inert matter tolerance

For Poa spp., Agrostis spp., Festuca spp., Andropogon spp., Bouteloua

spp., bromegrass, crested wheatgrass, western wheatgrass, molasses

grass, Guinea grass, Vasey grass, orchard grass, velvet grass, tall oatgrass, meadow foxtail, sweet vernal grass, Rhodes grass, Dallis grass,

carpet grass, Indian ricegrass, Bermuda grass, and wild-rye grass,

and mixtures containing these seeds singly or combined in excess of

50 percent, an additional tolerance shall be allowed. This is to be

obtained by multiplying the regular tolerance by the lesser of a and t

divided by 100.

To find the amount of tolerance (T) to be allowed on any value

given in tables 5, 6, 7, and 8 for percentage of pure seed, inert matter,

weed seed, or crop seed variation, first find the value in whole numbers

in the left column, then any fractional part in the horizontal column

at the top of the page. The tolerance (T) to be allowed on that value

will then be found at the intersection of the columns opposite the value

in whole numbers and below the fractional value.

The tolerance for pure seed of purity less than 50 percent is the

same as the tolerance for the larger part of the difference between

the purity and 100 percent. Example: The tolerance for a purity of

30 percent would be the same as for 100 percent —30 percent=70

percent, or tolerance on 70 percent of 4.80 percent.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 357

TABLE ^.—Tolerances for pure seed variations for other than certain

chaffy grasses

[Computed on the basis of Tolerance (T)=0.6 plus 20% of the formula aXö iivided by 100]

Value,

percent 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

100 0.60

0.79

100

99 '"5." 77 "Ö."75 '"Ö.'73 ~0.'7Ï "Ö.'69 "Ö."67 "Ö.'eö 'Ö.'63 "ö.'ei 99

98 LOO 0.98 0.96 0. 94 0.92 0.90 0.88 0.86 0.83 0.81 98

97 L18 1. 16 1. 14 L 12 L 10 L08 L06 1.05 1. 04 L 01 97

96 L36 L34 1. 33 L 31 1. 29 L27 L25 L23 L21 L20 96

95 L55 L52 1.50 L48 1.46 L45 L44 L42 L40 L38 95

94 L72 L 71 1.69 L67 L65 1. 63 L62 L60 1. 58 L56 94

93 1.90 1. 88 1. 86 L85 L83 L81 L 79 L78 1. 76 L74 93

92 2.07 2.05 2.03 2.02 2.00 1. 98 1. 96 L95 1.93 L91 92

91 2.23 2.22 2. 20 2. 18 2. 17 2. 15 2. 13 2. 12 2. 10 2.08 91

90 2.40 2. 38 2.36 2. 35 2. 33 2.31 2.30 2.28 2.27 2.25 90

89 2.55 2. 54 2.52 2. 51 2.49 2.47 2.46 2.44 2.43 2.41 89

88 2. 71 2. 68 2.67 2.66 2. 65 2.63 2.62 2.60 2.58 2.57 88

87 2.86 2.84 2.83 2.81 2.80 2.78 2.77 2. 75 2.74 2. 72 87

86 3.00 2. 99 2.97 2. 96 2. 95 2.93 2.92 2.90 2.89 2.87 86

85 3. 15 3. 13 3. 12 3. 10 3. 09 3.07 3.06 3.05 3.03 3.02 85

84 3.28 3. 27 3.26 3. 24 3.23 3. 21 3.20 3. 19 3. 17 3. 16 84

83 3.42 3.40 3. 39 3.38 3.36 3.35 3.34 3.32 3.31 3.30 83

82 3.55 3. 53 3.52 3.51 3.50 3.48 3.47 3.46 3.44 3.43 82

81 3.67 3. 66 3. 65 3. 64 3. 62 3.61 3.60 3.59 3.57 3.56 81

80 3.80 3. 78 3. 77 3.76 3. 75 3.73 3.72 3. 71 3.70 3.68 80

79 3.91 3. 90 3.89 3.88 3.87 3.85 3. 84 3.83 3. 82 3.81 79

78 4.03 4.02 4. 00 3. 99 3.98 3.97 3.96 3.95 3.94 3.92 78

77 4. 14 4. 13 4. 12 4. 10 4.09 4. 08 4. 07 4. 06 4. 05 4. 04 77

76 4. 24 4. 23 4. 22 4. 21 4.20 4. 19 4. 18 4. 17 4. 16 4. 15 76

75 4.35 4.33 4. 32 4.31 4. 30 4.29 4.28 4.27 4.26 4.25 75

74 4.44 4. 43 4.42 4.41 4.40 4.39 4.38 4.37 4.36 4.35 74

73 4. 54 4.53 4.52 4.51 4.50 4.49 4.48 4.47 4.46 4.45 73

72 4.63 4. 62 4. 61 4.60 4. 59 4.58 4.57 4. 56 4.56 4.55 72

71 4.71 4. 70 4.70 4. 69 4. 68 4. 67 4.66 4. 65 4. 64 4. 64 71

70 4.80 4.79 4. 78 4. 77 4. 76 4.75 4.75 4.74 4. 73 4.72 70

69 4. 87 4.87 4.86 4.85 4.84 4. 83 4. 83 4.82 4.81 4. 80 69

'68 4.95 4. 94 4. 93 4.93 4.92 4.91 4.90 4.90 4.89 4.88 68

f •; 67 5.02 5. 01 5.00 5.00 4. 99 4. 98 4. 98 4. 97 4.96 4.95 67

66 5.08 5. 08 5.07 5.06 5.06 5.05 5.04 5.04 5.03 5.02 66

65 5. 15 5. 14 5. 13 5. 13 5. 12 5. 11 5. 11 5. 10 5. 10 5. 09 65

64 5.20 5.20 5. 19 5. 19 5. 18 5. 17 5. 17 5. 16 5. 16 5. 15 64

63 5.26 5.25 5.25 5. 24 5. 24 5.23 5.23 5.22 5. 21 5. 21 63

62 5.31 5. 30 5. 30 5.29 5.29 5.28 5.28 5. 27 5.27 5.26 62

61 5.35 5.35 5. 34 5. 34 5. 34 5.33 5.33 5.32 5. 32 5. 31 61

60 5. 40 5.39 5.39 5. 38 5. 38 5. 37 5. 37 5.37 5. 36 5.36 60

59 5.43 5. 43 5. 43 5. 42 5. 42 5.41 5. 41 5.41 5.40 5.40 59

58 5.47 5.46 5.46 5.46 5.45 5. 45 5.45 5. 44 5. 44 5.44 58

57 5. 50 5. 49 5.49 5.49 5.49 5.48 5.48 5.48 5.47 5.47 57

56 5.52 5. 52 5. 52 5. 51 5. 51 5. 51 5. 51 5.51 5.50 5.50 56

55 5.55 5. 54 5. 54 5. 54 5. 54 5. 53 5. 53 5. 53 5. 53 5.53 55

54 5. 56 5. 56 5.56 5.56 5.56 5.55 5.55 5. 55 5. 55 5. 55 54

53 5. 58 5. 58 5. 57 5.57 5.57 5.57 5.57 5. 57 5. 57 5.56 53

52 5. 59 5. 59 5. 59 5. 58 5. 58 5.58 5.58 5.58 5.58 5.58 52

51 5. 59 5.59 5. 59 5.59 5. 59 5. 59 5.59 5. 59 5.59 5.59 51

50 5. 60 5. 59 5.59 5.59 5. 59 5. 59 5. 59 5. 59 5. 59 5.59 50
358 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

TABLE 6.—Tolerances for pure seed variations for the following chaffy

grasses: Poa spp,^ Agrostis spp,^ Festuca spp,^ hromegrass^ crested

wheatgra^s^ orchard grass^ velvet grass^ tall oatgrass^ meadoio foxtail^ sweet vernal grass^ Rhodes grass^ Dallis grass^ carpet grass^

Berviiuda grass^ Guinea grass^ molasses grass^ Vasey grass^ Andropogon spp,^ Bouteloua spp.^ Indian ricegrass and wild-rye^ and mixtures containing these seeds singly or combined in excess of 50 percent

[ The tolerance is obtained by adding to the regular tolerance the product obtained by multiplying the

regular tolerance by the lesser of a and b divided by 100]

Value,

percent 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

100 0.60

.79

100

99 "Ö."77 '"Ör75 "Ö.'73 '0.'7Í "Ó."69 'Ö.~67 ~Ö.'65 'Ó.'63 'ö.'ei 99

98 1.00 .98 . 96 .94 .92 .90 .88 .86 .83 .81 98

97 L21 1. 19 L 17 L 15 1. 12 1. 10 1. 08 1.07 L06 1.03 97

96 L 41 1. 39 1. 38 L35 L33 L31 L29 1.27 L24 1.23 96

95 1. 62 1.59 L57 L54 1. 52 1. 51 1. 50 1.48 L45 L43 95

94 L82 1.81 L78 L76 1.74 L71 1. 70 1. 68 1. 66 1.63 94

93 2.03 2.00 L98 L97 1. 95 L 92 L90 1.87 1. 86 1. 84 93

92 2.23 2.21 2. 18 2. 17 2. 15 2. 12 2. 10 2. 09 2. 06 2.04 92

91 2.43 2.41 2.39 2. 36 2. 35 2.33 2.30 2.28 2.27 2. 24 91

90 2.64 2.61 2.59 2.57 2.55 2.52 2.51 2. 49 2. 47 2.45 90

89 2.83 2.81 2.79 2. 77 2.75 2.72 2.71 2. 69 2.67 2.65 89

88 3.03 3. 01 2. 99 2. 97 2.95 2.93 2.91 2.89 2.86 2. 85 88

87 3.23 3.20 3. 19 3. 16 3. 15 3. 12 3. 11 3.08 3.07 3.04 87

86 3.42 3. 40 3. 37 3. 36 3. 35 3. 32 3.31 3.28 3.27 3.24 86

85 3.62 3.59 3.58 3.55 3. 54 3.51 3.50 3.48 3. 46 3.44 85

84 3.80 3.78 3.77 3.74 3. 73 3.70 3. 69 3.67 3.65 3.63 84

83 4.00 3.97 3.95 3.94 3.91 3.90 3.88 3.86 3.84 3.83 83

82 4. 18 4. 16 4. 14 4. 13 4. 11 4.08 4.07 4.05 4.03 4. 01 82

81 4.36 4.35 4.33 4.32 4.29 4.27 4.26 4.24 4.21 4.20 81

80 4. 56 4. 53 4. 51 4. 49 4. 48 4. 46 4. 44 4. 42 4. 41 4. 38 80

79 4.73 ¿71 4. 69 4.68 4. 66 4. 63 4. 62 4. 60 4.59 4.57 79

78 4.92 4i 90 4, 87 4. 85 4. 83 4. 82 4.80 4.79 4.77 4. 74 78

77 5.09 5.07 5.05 5.03 5.01 4.99 4.98 4. 96 4. 94 4.93 77

76 5. 25 5. 24 5. 22 5.20 5. 19 5. 17 5. 15 5. 14 5. 12 5. 10 76

75 5.43 5.40 5.39 5.37 5.35 5.34 5.32 5.30 5.29 5. 27 75

74 5.59 5.57 5.56 5. 54 5.52 5.50 5.49 5.47 5.45 5.44 74

73 5. 76 5.74 5.73 5.71 5.69 5.67 5.66 5.64 5. 63 5. 61 73

72 5.92 5.90 5.89 5.87 5.85 5.83 5.82 5.80 5.80 5.78 72

71 6. 07 6.05 6.05 6.03 6.01 6.00 5. 98 5.96 5. 94 5. 94 71

70 6. 24 6. 22 6.20 6. 18 6. 16 6. 15 6. 14 6. 12 6. 11 6.09 70

69 6.37 6.37 6.35 6.33 6.32 6.30 6.29 6.28 6.26 6. 24 69

68 6. 53 6. 51 6. 49 6. 49 6. 47 6. 45 6. 43 6. 43 6. 41 6. 39 68

67 6.67 6. 65 6. 64 6.63 6.61 6.59 6.59 6.57 6.55 6.53 67

66 6.80 6.80 6.78 6.76 6.76 6. 74 6.72 6.71 6.71 6. 68 66

65 6. 95 6.93 6.91 6. 91 6.89 6.87 6.86 6. 84 6. 84 6. 82 65

64 7.07 7. 06 7.04 7.04 7.02 7.00 7.00 6. 98 6.97 6.95 64

63 7.20 7. 18 7. 18 7. 16 7. 15 7. 13 7. 13 7. 11 7.09 7.09 63

62 7.32 7.30 7.30 7.28 7.27 7.26 7.25 7.23 7.23 7.21 62

61 7.43 7.43 7.41 7.40 7.40 7.38 7.36 7. 35 7.35 7.33 61

60 7. 56 7. 54 7.53 7.51 7.51 7. 49 7. 48 7. 48 7.46 7.45 60
TESTING AGRICULTURAL AND VEGETABLE SEEDS 359

TABLE 6.—Tolerances for pure seed variations for the foUo%oing chaffij

grasses^ etc,—Continued

Value,

percent 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

59 7. 65 7.65 7. 64 7. 62 7.62 7.60 7. 59 7. 59 7.57 7.56 59

58 7.76 7.74 7. 74 7.73 7.71 7.71 7.70 7.68 7.68 7.67 58

57 7. 86 7.84 7.83 7.83 7.82 7.80 7.80 7.79 7. 77 7.77 57

56 7.94 7.94 7.93 7.93 7.91 7.90 7.90 7.89 7.87 7. 87 56

55 8.04 8.02 8.02 8.01 8.01 7. 99 7.98 7.97 7.97 7.96 55

54 8. 11 8. 11 8. 10 8. 10 8.09 8.07 8.06 8.06 8.05 8.05 54

53 8.20 8. 19 8. 17 8. 17 8. 16 8. 16 8. 15 8. 14 8. 14 8. 12 53

52 8. 27 8.26 8.26 8. 24 8. 23 8. 23 8.22 8.21 8. 21 8.20 52

51 8.32 8.32 8. 31 8.31 8.30 8.30 8. 29 8.28 8.28 8.27 51

50 8.40 8.37 8.37 8.36 8.36 8. 35 8.35 8,34 8.34 8. 33 50

Regular Tolerance +

Regular Tolerance X(100—value)

100

Example: Tolerance for 91.40 percent.

Regular Tolerance 2.17 percent.

2.17X (100-91.40)

100 2.17+-

Tolerance 2.35 percent.

2.17+

2.17+ ^,,

2.17+0.18

2.17X8.60

100

18.5620

TABLE 7.—Tolerances for weed seeds^ other crop seed^ and inert matter

for other than certain chaffy grasses

[Computed on the basis of Tolerance (T) = 0.2 plus 20% of the formula 0X6 divided by 100]

Value,

percent 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

0 0. 20 0. 21 0. 23 0. 25 0.27 0,29 0.31 0.33 0.35 0.37 0

1 .39 . 41 .43 .45 .47 .49 .51 .53 . 55 .57 1

2 .59 .61 .63 . 65 .66 .68 .70 .72 .74 .76 2

3 .78 .80 .81 .83 . 85 .87 .89 . 91 .93 .94 3

4 .96 .98 LOO L02 1. 04 L05 L06 L08 L 10 L 12 4

5 1. 15 L 16 L 18 1. 20 1. 22 1. 23 1. 25 1. 27 1. 29 L31 5

6 L32 L34 L36 L38 L39 1. 41 L43 L45 L46 L48 6

7 1. 50 L 51 1. 53 1. 55 L 56 L58 L60 L62 L63 1. 65 7

8 L67 1. 68 L70 L72 1. 73 L75 1. 77 L78 1. 80 1.82 8

9 L83 L85 L87 L88 L90 L91 1. 93 L95 L96 L98 9

10 2.00 2. 01 2. 03 2. 04 2. 06 2. 07 2. 09 2. 11 2. 12 2. 14 10

11 2. 15 2. 17 2. 18 2.20 2.22 2.23 2.25 2.26 2.28 2.29 11

12 2.31 2.32 2.34 2.35 2.37 2.38 2.40 2.41 2. 43 2.44 12

13 2.46 2.47 2.49 2. 50 2. 52 2. 53 2. 55 2. 56 2.57 2. 59 13

14 2.60 2.62 2.63 2.65 2.66 2.67 2.69 2.70 2.72 2.73 14
360 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

TABLE 7.—Tolerances for weed seeds^ other crop seed^ and inert matter

for other than certain chaffy grasses—Continued

Value,

percent 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

15 2.75 2.76 2.77 2.79 2.80 2.81 2.83 2.84 2.86 2.87 15

16 2.88 2.90 2.91 2. 92 2.94 2.95 2,96 2.98 2,99 3.00 16

17 3.02 3.03 3.04 3,06 3.07 3.08 3, 10 3. 11 3. 12 3. 13 17

18 3. 15 3. 16 3. 17 3. 19 3.20 3.21 3.22 3. 24 3.25 3. 26 18

19 3.27 3. 28 3.30 3.31 3.32 3.33 3.35 3.36 3.37 3.38 19

20 3.40 3.41 3.42 3.43 3. 44 3.45 3.47 3.48 3.49 3. 50 20

21 3.51 3.52 3. 54 3.55 3.56 3.57 3. 58 3. 59 3.60 3. 62 21

22 3.63 3.64 3.65 3.66 3.67 3.68 3.69 3.70 3. 72 3. 73 22

23 3.74 3.75 3.76 3.77 3.78 3.79 3.80 3.81 3.82 3. 83 23

24 3.84 3.85 3.86 3.87 3.88 3.89 3.90 3. 91 3. 92 3.93 24

25 3.95 3.95 3.96 3. 97 3.98 3.99 4.00 4. 01 4.02 4.03 25

26 4.04 4.05 4.06 4.07 4.08 4.09 4. 10 4. 11 4. 12 4. 13 26

27 4. 14 4, 15 4. 16 4. 16 4. 17 4. 18 4. 19 4. 20 4.21 4.22 27

28 4,23 4.24 4.24 4.25 4. 26 4.27 4.28 4, 29 4. 30 4.30 28

29 4.31 4.32 4.33 4.34 4. 35 4. 35 4.36 4,37 4.38 4. 39 29

30 4.40 4.40 4.41 4.42 4.43 4. 43 4.44 4.45 4. 46 4.47 30

31 4.47 4.48 4.49 4.50 4.50 4.51 4. 52 4.53 4.53 4.54 31

32 4. 55 4.55 4.56 4. 57 4. 58 4. 58 4.59 4.60 4. 60 4. 61 32

33 4.62 4.62 4. 63 4. 64 4. 64 4.65 4. 66 4.66 4. 67 4.68 33

34 4.68 4,69 4.70 4.70 4.71 4.71 4, 72 4.73 4.73 4. 74 34

35 4,75 4.75 4.76 4. 76 4.77 4.77 4.78 4. 79 4.79 4.80 35

36 4.80 4.81 4.81 4.82 4.83 4.83 4. 84 4. 84 4. 85 4.85 36

37 4.86 4.86 4.87 4.87 4. 88 4. 88 4.89 4.89 4.90 4.90 37

38 4.91 4. 91 4. 92 4.92 4.93 4.93 4.94 4. 94 4. 94 4.95 38

39 4.95 4.96 4.96 4.97 4. 97 4. 97 4.98 4.98 4.99 4.99 39

40 5.00 5.00 5.00 5.00 5.01 5.01 5.02 5.02 5.03 5.03 40

TABLE 8.—Tolerances for inert matter^ weed seed^ and crop seed for

chaffy grasses^ as follows: Poa spp,^ Agrostis spp,^ Festuca spp,^

hromegrass^ crested wheatgrass^ orchard grass^ velvet gra^s^ tall

oatgrass^ meadow foxtail^ sweet vernal grass^ Rhodes grass^ Dallis

grass^ carpet grass, Bermuda grass, Guinea grass, molasses grass,

Vasey grass, Andropogon spp,, Bouteloua spp,, Indian ricegrass and

wild-rye, and mixtures coritaining these seeds singly or comhined in

excess of 60 percent

[The tolerance is obtained by adding to the regular tolerance the product obtained by multiplying the

regular tolerance by the lesser of a and b divided by 100]

Value,

percent 0.00 0.10 0.20 0,30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

0 0. 20 0.21 0.23 0.25 0.27 0.29 0.31 0,33 0.35 0, 37 0

1 .39 . 41 .43 .45 .47 .49 . 51 .53 . 55 .58 1

2 .60 .62 .64 .66 . 67 . 69 .71 .73 .76 .78 2

3 .80 .82 .83 .85 .87 . 90 .92 .94 .96 .97 3

4 .99 1.02 1,04 1.06 1.08 1.09 1. 10 1. 13 1. 15 1. 17 4
TESTING AGRICULTURAL AND VEGETABLE SEEDS 361

TABLE 8.—Tolérances for inert matter^ weed seed^ and crop seed for

chaffy grasses^ etc,—Continued

Value,

percent 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Value,

percent

5 1.20 1.21 1.24 L26 1.28 1.29 1. 31 1.33 1.35 1.37 5

6 1.39 1.42 1.44 1. 46 1.47 1.50 1.52 1. 54 1. 55 1.58 6

7 1. 60 1.61 1.64 1. 66 1.67 1.69 1.72 1.74 1.75 1.78 7

8 1.80 1.81 1.83 L86 1.87 L89 1. 92 1. 93 1.95 1.98 8

9 1.99 2.01 2.04 2.06 2.07 2.09 2. 11 2. 13 2. 15 2.17 9

10 2.20 2. 21 2.23 2.25 2.27 2.28 2.31 2.33 2.34 2.37 10

11 2. 38 2.41 2.42 2.44 2.47 2. 48 2.51 2.52 2.54 2.56 11

12 2.58 2. 60 2.62 2.63 2.66 2.67 2.70 2.71 2.74 2.75 12

13 2.77 2.79 2.81 2.83 2.85 2.87 2.89 2.91 2.92 2.95 13

14 2,96 2.98 3.00 3.03 3.04 3.05 3.07 3.09 3. 12 3. 13 14

15 3. 16 3. 17 3. 19 3.21 3.23 3.24 3.26 3.28 3.29 3.32 15

16 3.34 3.36 3.38 3.39 3.42 3. 43 3.45 3.47 3.49 3.50 16

17 3.53 3.54 3.56 3.58 3.60 3.61 3.64 3.66 3.67 3.69 17

18 3.71 3.73 3.74 3.77 3.78 3.80 3.81 3.84 3.86 3.87 18

19 3.89 3.90 3.93 3.94 3.96 3.97 4.00 4.02 4.03 4.05 19

20 4.08 4.09 4. 11 4. 12 4. 14 4. 15 4. 18 4.20 4.21 4.23 20

21 4. 24 4.26 4.29 4.30 4.32 4.33 4.35 4.36 4.38 4.41 21

22 4.42 4.44 4.46 4. 47 4.49 4.50 4.52 4.53 4. 56 4. 58 22

23 4.60 4. 61 4.63 4. 64 4.66 4.68 4.69 4.71 4.72 4.74 23

24 4.76 4.77 4.79 4.81 4.82 4.84 4.85 4.87 4.89 4. 90 24

25 4. 93 4. 94 4.95 4.97 4,99 5.00 5.02 5.04 5.05 5.07 25

26 5.09 5. 10 5. 12 5. 14 5. 15 5. 17 5. 19 5.20 5.22 5.24 26

27 5.25 5.27 5.29 5.29 5.31 5.32 5.34 5.36 5.38 5.39 27

28 5.41 5.43 5. 43 5.45 5.46 5.48 5.50 5, 53 5.53 5.54 28

29 5.55 5.57 5.59 5.61 5.62 5.63 5.65 5.66 5.68 5.70 29

30 5.72 5.72 5.74 5.75 5.77 5.78 5.79 5.81 5.83 5.85 30

31 5.85 5.87 5.89 5. 90 5.91 5.93 5.94 5.96 5.97 5.98 31

32 6.00 6.01 6.02 6.04 6.06 6.06 6.08 6. 10 6. 10 6. 12 32

33 6. 14 6. 14 6. 16 6. 18 6. 18 6.20 6.22 6.23 6.24 6.26 33

34 6.27 6.28 6.30 6.31 6.33 6.33 6.35 6.37 6.37 6.39 34

35 6.41 6.41 6.43 6.44 6.45 6.46 6.48 6.50 6.50 6.52 35

36 6. 52 6. 54 6. 55 6.55 6. 58 6.59 6.61 6. 61 6.63 6.63 36

37 6,65 6.66 6.68 6.68 6.70 6.71 6.72 6.73 6.75 6.75 37

38 6.77 6.78 6.79 6.80 6.82 6.82 6.84 6.85 6. 85 6.87 38

39 6.88 6.89 6.90 6.92 6. 92 6.93 6.95 6.95 6.97 6.98 39

40 7.00 7.00 7.01 7.01 7.03 7.03 7.05 7.06 7.08 7.08 40

Regular Tolerance+ (Regular Tolerance X value)

100

Example; Tolerance for 9.10 percent

Tolerance 2.01 percent.

1.85+

1.85+ ^^^

1.85 +0.16

(1.85X9.10)

100

16.8350
362 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Noxious-Weed Seeds

The tolerances (table 9) for rates of occurrence of noxious-weed

seeds shall be recognized and shall be applied to the number of

noxious-weed seeds found by analysis in the quantity of seed specified

for noxious-weed seed determinations. Representations showing the

rate of occurrence indicated in table 9, columns 2, 4, and 6 will be considered within the tolerance if no more than the accompanying numbers in columns 1, 3, and 5 are found by analysis. For rates of occurrence higher than those shown in table 9 and in case of additional or

more extensive analyses, a tolerance based on a degree of certainty of

5 percent (P=0.05) will be recognized.

TABLE 9.—Tolerances for noxious-weed seeds

fBased on the Poisson distribution and calculated from the formula Y= X+ V3.841 X+1: F=the number

in the first column and X=the number in the second column]

Number The following Number The following Number The following

found by are within found by are within found by are within

analysis the tolerance analysis the tolerance analysis the tolerance

2 0 56 42 103 84

4 1 57 43 104 85

6 2 b^ 44 105 86

8 3 59 45 106 87

9 4 60 46 107 88

11 5 61 47 108 89

12 6 63 48 110 90

13 7 64 49 111 91

14 8 65 50 112 92

16 9 66 51 113 93

17 10 67 52 114 94

18 11 68 53 115 95

20 12 69 54 116 96

21 13 71 55 117 97

22 14 72 56 118 98

23 15 73 57 120 99

24 16 74 58 121 100

25 17 75 59 122 101

27 18 76 60 123 102

28 19 77 61 124 103

29 20 78 62 125 104

30 21 80 63 126 105

32 22 81 64 127 106

33 23 82 65 128 107

34 24 83 66 129 108

35 25 84 67 130 109

37 26 85 68 132 110

38 27 86 69 133 111

39 28 87 70 134 112

41 29 89 71 135 113

42 30 90 72 136 114

43 31 91 73 137 115

44 32 92 74 138 116

45 33 93 75 139 117

46 34 94 76 140 118

48 35 95 77 141 119

49 36 96 78 142 120

50 37 97 79 144 121

51 38 99 80 145 122

52 39 100 81 146 123

53 40 101 82 147 124

55 41 102 83 148 125
TESTING AGRICULTURAL AND VEGETABLE SEEDS 363

TABLE 9.—Tolerances for noxioiùs-weed seeds—Continued

Number The following Number The following Number The following

found by are within found by are within found by are within

analysis the tolerance analysis the tolerance analysis the tolerance

149 126 213 185 276 244

150 127 214 186 277 245

151 128 215 187 278 246

152 129 216 188 279 247

153 130 217 179 280 248

154 131 218 190 281 249

156 132 219 191 282 250

157 133 220 192 283 251

158 134 221 193 284 252

159 135 222 194 285 253

160 136 223 195 286 254

161 137 224 196 287 255

162 138 226 197 288 256

163 139 227 198 289 257

164 140 228 199 290 258

165 141 229 200 292 259

166 142 230 201 293 260

167 143 231 202 294 261

169 144 232 203 295 262

170 145 233 204 296 263

171 146 234 205 297 264

172 147 235 206 298 265

173 148 236 207 299 266

174 149 237 208 300 267

175 150 238 209 301 268

176 151 239 210 302 269

177 152 240 211 303 270

178 153 242 212 304 271

179 154 243 213 305 272

180 155 244 214 306 273

181 156 245 215 307 274

183 157 246 216 309 275

184 158 247 217 310 276

185 159 248 218 311 277

186 160 249 219 312 278

187 161 250 220 313 279

188 162 251 221 314 280

189 163 252 222 315 281

190 164 253 223 316 282

191 165 254 224 317 283

192 166 255 225 318 284

193 167 256 226 319 285

194 168 258 227 320 286

195 169 259 228 321 287

197 170 260 229 322 288

198 171 261 230 323 289

199 172 262 231 324 290

200 173 263 232 325 291

201 174 264 233 326 292

202 175 265 234 328 293

203 176 266 235 329 294

204 177 267 236 330 295

205 178 268 237 331 296

206 179 269 238 332 297

207 180 270 239 333 298

208 181 271 240 334 299

209 182 272 241 335 300

211 183 273 242

212 184 275 243
364 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

FLUORESCENCE TEST AND 400- TO 1,000-SEED SEPARATIONS

Tolerances shall be recognized and applied to fluorescence test results of Lolium spp. and 400-seed separations (or a larger number

of seeds) in purity analyses. These tolerances recognize the sampling

error introduced by the small number of seeds used and are to be

applied in determining the variations for those factors affected by

the use of a small number of seeds. If the results of fluorescence tests

or 400- to 1,000-seed separations are used in computing the percentages of pure seed of a sample, one-half the regular pure seed tolerance shall be added to the toJerance for the fluorescence test or 400-

to 1,000-seed separations. The tolerances to be used shall be determined from the formula published by Leggatt in Bot. Rev. 5 (9) :

505-529, 1939, and in the Association of Official Seed Analysts Proceedings, pages 101-107, 1935, computed to a certainty of 5 percent

(P=0.05). The formula is complicated and is not given as a part

of table 10.

TABLE 10.—Tolerances for fluorescence tests and IpOO- to IfiOO-seed

separations in purity analysis ^

[Based on the requirement that when 2 independent trials or tests have been made on the same properly

mixed bulk lot, the chances of divergence between the 2 trials exceeding the tolerance will not be greater

than 1 in 20]

Number of

seeds in test

to which tol- 400 400 800 800 400 800 1,000 1,000 1,000

erance is to

be applied

Number of

seeds used

in other test

400 800 400 800 1,000 1,000 1,000 800 400

100 percent _

99 percent

98 percent

97 percent

96 percent

1.0

1. 6

2.0

2.3

0.8

1.3

1.7

1.9

0.9

1. 4

1.8

2.2

0.8

1.2

1.4

1.7

0. 7

1. 2

1. 5

1.8

0.7

1.0

1.3

1. 6

0.7

1.0

1.3

1.5

0. 8

1. 2

1. 4

1.7

0.9

1,4

1.8

2. 1

95 percent

94 percent

93 percent

92 percent

91 percent

2.6

2.9

3.2

3.4

3.6

2.2

2.4

2.7

2.8

3. 1

2.4

2.7

2.9

3. 1

3.3

1.9

2. 1

2.3

2. 4

2. 6

2. 1

2.3

2. 5

2.7

2. 9

1.8

2.0

2. 1

2.3

2. 4

1. 7

1.9

2.0

2.2

2.3

1.8

2.0

2.2

2.3

2. 5

2.4

2.6

2.8

3.0

3.2

90 percent

89 percent

88 percent

87 percent

86 percent

3.8

4.0

4. 1

4.3

4. 5

3.2

3.4

3. 5

3.7

3.8

3.4

3.6

3.7

3. 9

3.9

2. 8

2.9

3.0

3. 1

3.2

3.0

3. 1

3.2

3.4

3.6

2.6

2.7

2. 8

2.9

3.0

2.4

2.5

2. 7

2.8

2.9

2.7

2.8

2. 9

2.9

3. 1

3.3

3.4

3.6

3.8

3. 9

85 percent

84 percent-^--

83 percent

82 percent

81 percent

4.7

4.8

4. 9

5.0

5. 2

3.9

4. 1

4.2

4. 3

4.4

4. 1

4. 2

4.3

4. 4

4. 5

3.3

3. 4

3.5

3.6

3.7

3.7

3.9

4.0

4. 1

4. 2

3. 1

3.2

3.3

3.4

3. 5

2.9

3.0

3. 1

3.2

3. 3

3.2

3. 3

3.3

3.4

3. 5

4.0

4. 1

4.2

4.3

4.4

See footnote at end of table.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 365

TABLE 10.—Tolerances for fluorescence tests and IfiO- to ipOO-seed

separations in purity analysis'^—Continued

Number of

seeds in test

to which tol- 400 400 800 800 400 800 1,000 1,000 1,000

erance is to

be applied

Number of

seeds used 400 800 400 800 1,000 1,000 1,000 800 400

in other test

80 percent 5.3 4.5 4.7 3.8 4.3 3.5 3.3 3.6 4. 5

79 percent 5.4 4.6 4.7 3. 8 4.4 3.6 3.4 3.7 4.6

78 percent 5.5 4.7 4.8 3.9 4.5 3.7 3.5 3.7 4.7

77 percent 5.6 4.8 4.9 4.0 4. 6 3.7 3.5 3.8 4.8

76 percent 5.7 4.9 5.0 4. 1 4.6 3.8 3.6 3.8 4.8

75 percent 5.8 5.0 5. 1 4. 1 4.7 3.9 3.7 3.9 4.9

74 percent 5.8 5.0 5. 1 4.2 4.8 3.9 3.7 3.9 5.0

73 percent 5.9 5. 1 5.2 4.2 4.9 4.0 3.8 4.0 5. 1

72 percent-— 6. 0 5.2 5.3 4.3 4.9 4.0 3.8 4. 1 5. 1

71 percent 6. 1 5. 2 5. 3 4. 3 5.0 4. 1 3.9 4. 1 5.2

70 percent 6. 2 5.3 5.4 4.4 5. 1 4. 1 3.9 4.2 5.2

69 percent 6.2 5.4 5.5 4.4 5. 1 4. 2 3.9 4.2 5.3

68 percent 6.3 5.4 5.5 4.5 5.2 4.2 4.0 4.3 5.3

67 percent 6.3 5.5 5.6 4.5 5.2 4. 2 4.0 4.3 5.4

66 percent 6.4 5.5 5. 6 4. 6 5.3 4.3 4.0 4.3 5. 4

65 percent 6. 5 5. 6 5.7 4.6 5.3 4.3 4. 1 4.3 5.4

64 percent 6.5 5.6 5.7 4.6 5.4 4.3 4. 1 4. 4 5.5

63 percent 6. 5 5.7 5.7 4.7 5.4 4.4 4. 1 4.4 5.6

62 percent 6. 6 5.7 5.8 4.7 5.4 4.4 4.2 4.4 5.6

61 percent--.-- 6.6 5.7 5.8 4.7 5.5 4.4 4.2 4.4 5.6

60 percent 6.7 5.8 5.8 4.8 5.5 4.5 4.2 4.5 5.6

59 percent 6.7 5.8 5.9 4.8 5.5 4.5 4.2 4. 5 5.7

58 percent 6.8 5. 8 5. 9 4. 8 5. 6 4.5 4.2 4.6 5.7

57 percent 6.8 5.9 5.9 4.8 5.6 4.5 4.3 4.6 5.7

56 percent 6.8 5.9 5. 9 4.8 5.6 4.5 4.3 4.6 5.7

55 percent 6.8 5.9 5.9 4.9 5.7 4.6 4.3 4. 6 5. 8

54 percent 6.9 5. 9 6.0 4.9 5.7 4.6 4.3 4.6 5.8

53 percent 6.9 5.9 6.0 4.9 5.7 4.6 4.3 4.6 5.8

52 percent 6.9 6.0 6.0 4.9 5.7 4. 6 4.3 4.7 5.8

51 percent 6.9 6.0 6.0 4.9 5.7 4.6 4.3 4.7 5.8

50 percent 6.9 6.0 6.0 4.9 5.7 4.6 4.3 4.7 5.8

49 percent 6.9 6.0 6.0 4. 9 5.7 4.6 4. 3 4.7 5.8

48 percent 6. 9 6.0 6.0 4.9 5.7 4.6 4.3 4.7 5.8

47 percent 6.9 6.0 6.0 4.9 5.7 4.6 4.3 4.7 5.8

46 percent 6.9 6. 0 6.0 4.9 5.7 4.6 4. 3 4.7 5. 8

45 percent 6.9 6.0 6.0 4.9 5.7 4. 6 4.3 4.7 5.8

44 percent 6.9 6.0 6.0 4.9 5.7 4.6 4.3 4.7 5.8

43 percent 6.9 6.0 6.0 4.9 5.7 4. 6 4.3 4. 6 5.8

42 percent 6. 9 6.0 6. 0 4.9 5.7 4. 6 4.3 4.6 5.8

41 percent 6.9 6.0 5.9 4.9 5.7 4.6 4.3 4.6 5.7

40 percent 6.9 6.0 5.9 4.8 5.7 4. 6 4.3 4.6 5.7

39 percent 6.8 5. 9 5. 9 4.8 5.7 4.5 4.3 4. 6 5. 7

38 percent 6.8 5.9 5.9 4.8 5.7 4.5 4. 3 4. 5 5. 7

37 percent 6. 8 5. 9 5.9 4.8 5.7 4.5 4.2 4.5 5.6

36 percent 6.8 5.9 5.8 4.8 5.6 4.5 4.2 4. 5 5. 6

See footnote at end of table.

957116—52 25
366 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

TABKE 10.—Tolerances for fluorescence tests and IßO- to IfiOO-seed

separations in purity analysis ^—Continued

Number of

seeds in test

to which tol- 400 400 800 800 400 800 1,000 1,000 1,000

erance is to

be applied

Number of

seeds used 400 800 400 800 1,000 1,000 1,000 800 400

in other test

35 percent 6.7 5.9 5.8 4.7 5.6 4.5 4.2 4.4 5.6

34 percent 6.7 5.8 5.8 4.7 5.6 4. 4 4.2 4. 4 5.6

33 percent 6.7 5.8 5.7 4.7 5.5 4.4 4. 1 4.4 5.5

32 percent 6.6 5.8 5.7 4.7 5.5 4. 4 4. 1 4.4 5.4

31 percent 6. 6 5.7 5.6 4. 6 5.5 4.3 4. 1 4.3 5.4

30 percent 6. 5 5.7 5. 6 4. 6 5.4 4.3 4.0 4.3 5.4

29 percent 6.5 5.6 5.6 4.6 5.4 4.3 4.0 4.3 5.3

28 percent 6.4 5. 6 5. 5 4. 5 ^5.4 4.2 4.0 4.3 5.3

27 percent 6.4 5.5 5. 4 4.5 '5.3 4.2 3.9 4.2 5.2

26 percent 6.3 5.5 5.4 4.4 5.3 4. 1 3.9 4.2 5.2

25 percent 6.2 5.4 5.3 4.4 5.2 4. 1 3.8 4. 1 5. 1

24 percent 6.2 5. 4 5.2 4.3 5. 1 4.0 3.8 4. 1 5.0

23 percent 6. 1 5.3 5.2 4.3 5. 1 4.0 3.7 4.0 4.9

22 percent 6.0 5.2 5. 1 4. 2 5.0 3.9 3.7 3. 9 4.9

21 percent 5.9 5.2 5.0 4. 1 4.9 3.9 3.6 3.9 4.8

20 percent 5.9 5. 1 4.9 4. 1 4.9 3.8 3.6 3.8 4.8

19 percent 5.7 5.0 4.9 4.0 4.8 3.8 3.5 3.8 4.7

18 percent 5. 6 4.9 4.8 3.9 4.7 3.7 3.4 3.7 4.6

17 percent 5.5 4.8 4.7 3.8 4. 6 3. 6 3.4 3. 6 4.4

16 percent 5. 4 4.7 4.6 3.8 4.5 3.5 3.3 3.5 4. 4

15 percent 5.3 4.6 4.5 3.7 4.4 3.4 3.2 3.4 4.3

14 percent 5.2 4.5 4.3 3. 6 4.3 3.4 3. 1 3.3 4.2

13 percent 5.0 4. 4 4.2 3.5 4.2 3.3 3.0 3.3 4.0

12 percent 4. 9 4.3 4. 1 3.4 4. 1 3.2 2.9 3.2 3.9

11 percent 4.7 4. 1 3.9 3.3 4.0 3.0 2.8 3. 1 3.8

10 percent 4.6 4. 0 3.8 3. 1 3.8 2.9 2.7 2.9 3. 6

9 percent 4.4 3.8 3.6 3.0 3.7 2.8 2.6 2.8 3.4

8 percent 4.2 3.7 3.5 2.9 3.5 2.7 2. 5 2. 7 3.3

7 percent 4.0 3.5 3.3 2.7 3.3 2.5 2.4 2.5 3. 1

6 percent 3. 7 3.3 3. 1 2.5 3. 1 2. 4 2. 2 . 2. 4 2.9

5 percent 3. 5 3. 1 2.9 2.4 2. 9 2. 2 2.0 2.2 2.7

4 percent 3.2 2.8 2.6 2.2 2.7 2.0 L9 2. 0 2.4

3 percent 2.8 2.5 2. 3 L9 2.4 L8 L6 L8 2. 2

2 percent 2. 4 2.2 1.9 1.6 2. 1 1. 5 1. 4 L5 L8

1 percent L8 L7 L4 L3 1. 7 1. 1 1. 0 L2 1. 4

0 percent LO LO . 5 .5 . 4 . 4 .3 . 4 . 4

1 Method of using table: Enter the percentage to which the tolerance is to be

applied in the left-hand column. Next, find in the top horizontal row the number

of seeds used in your test and to which the tolerance is to be applied; then, find

in the second row the number of seeds used in the test with which your results are

to be compared. (If the number of seeds is not known assume that 400 seeds were

used.) The corresponding tolerance will be found in the appropriate column and

should be added to the percentage for which the tolerance is required.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 367

Examples

1. Laboratory A reported 97.80 percent perennial ryegrass seed by

applying the results of a 400-seed fluorescence test to the formula for

determining percentage of ryegrass. Upon testing a sample of this

seed, laboratory B found 94.6 percent perennial ryegrass based on 98.60

percent ryegrass and a 400-seed fluorescence test which gave 8 percent

fluorescence and 82 percent nonfluorescence. Does the result of laboratory B confirm the report of laboratory A ?

{a) Perennial ryegrass found by laboratory B =

1.0526X82.00X98.60

90 - = 94.56^

(b) One-half pure seed tolerance for 98.60% ryegrass=0.44%

{c) Fluorescence tolerance for 91.1% in the

Z (laboratory A)^^^^ column = 3.6%

Total tolerance=4.04%

{d) Laboratory B found 94.6 percent ryegrass plus 4.04 percent

tolerance=98.64 percent and thus confirmed the report of laboratory

A. Note that the 91.1 percent used in determining the fluorescence

tolerance (operation No. 3 above) is the product :

Number of nonfluorescent seeds ^^^^Qí ^CY

Number of seeds germinating 360 * ^^

It is necessary to use the tolerance applicable to the nonfluorescence

value since the total tolerance should finally be applied to the perennial ryegrass value.

2. Laboratory A rg)orted a pure seed percentage of 87.65 for

Kentucky bluegrass. Upon testing a sample of this seed, laboratory

B found a pure seed content of 80.08 percent for Kentucky bluegrass.

In making its test laboratory B found 86.57 percent Poa spp. in a

1-gram working sample ; upon examination of 1,000 seeds of the Poa

spp. 92.5 percent of these seeds was found to be Kentucky bluegrass

and 7.5 percent Canada bluegrass. Did Laboratory B confirm the

report of laboratory A with respect to pure seed for Kentucky bluegrass ?

(a) Pure seed found by laboratory B = 86.57X92.5 = 80.08%

(5) % pure seed tolerance for Poa species (chaffy grasses) for

86.57% = 1.66%

{c) Tolerance for 1,000-seed examination in the 92.5% line and the

1,000 ( laboratory B) ^

400 (laboratory A) ^^^"^ column 2.J /o

(d) Total tolerance=4.56 percent.

Laboratory B found 80.08 percent pure seed plus 4.56 percent tolerance=84.64% which does not confirm the report of Laboratory A.

Since we do not know the size of the sample used by laboratory A,

we must assume that this laboratory followed the rules and used at

least 400 seeds in separating the two kinds of seeds having similar

characteristics.
368 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Germination

The following tolerances are applicable to the percentages of germination and also to the sum of the germination plus the hard seed when

400 or more seeds are tested :

Found dy test

96 or over 5

90 or over but less than 96 6

80 or over but less than 90 7

In table 11 these tolerances have been added to germination values

ranging from 50 to 99 percent for tests based on 400 or more seeds.

When only 200 seeds of mixtures are tested 2 percent shall be added

to the above germination tolerances.

Tolerance Found hy test Tolerance

70 or over but less than 80 *_ 8

60 or over but less than 70 9

Less than 60 10

TABLE 11.-—Tolerances for germination tests

Percent found by test

The following are

within

tolerance

Percent found by test

The following are

within

tolerance

99 100

100

100

100

100

100

99

98

97

96

96

95

94

93

92

91

90

89

88

87

87

86

85

84

83

74 82

98 73 _ 81

97 72 80

96 71 _ 79

95 70 78

94 69 78

93 68 _ 77

92 67 76

91 66 75

90 65 74

89 64 73

88 63 _ 72

87 62 71

86 61 _ _ 70

85- 60 69

84 59 69

83 58 68

82 57 67

81 56 66

80 _ _ 55 65

79 54 _ . _ _ 64

78 53 63

77 52 62

76 51 _ 61

75 50 60
SAMPLE RECORD AND REPORT FORMS

Lab.

No. Kind

SAMPLE PURITY RECORD CARD

Sender's

mark

Received Kind of test Time of test Checked by Character of inert

Test made by Date Pm'e

Weight Percent

Crop

Noxious-weed seed according to

Sent by law; based on examination of gm.

Address Inert

Remarks Weed

Weight of sample -

Date reported

Final Original

>

O

d

Si

;>

>

<!

o

fei

Ui

Ü

Weed seeds Crop seeds

CO

CO
370 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

SAMPLE GERMINATION RECORD CARD

Lab. No. Kind

Gen

Spec

Teir

Sub.

Tiination test begun...

îial treatment

iperature ''C

stratum

Number of seeds tested. ._

3

10. —

bjo

1

i 14

!

i 21

1 28....

a rrotai -.

o

^ Average percent

Total

Average percent

-3

rotai

Average percent

-0
SAMPLE FORM FOR REPORTING PURITY OR PURITY AND GERMINATION TEST RESULTS

REPORT OF PURITY TEST OF SEED RECEIVED

Test No. Sender's mark Name of seed Pure seed

(percent)

Crop seed

(percent)

Inert

(percent)

Weed seed

(percent)

>

I—I

d

>

Ö

<î

O

Ö

ce

00

Remarks:

Weed seeds Percent

by weight Crop seeds Percent

by weight

Germination test Noxious-weed seed examination

Duration of

test in days

Germination

(percent)

Hard seed

(percent)

Noxious-weed seed according to State

seed law based on examination of grams

Number of

seeds found

Remarks:
SAMPLE FORM FOR REPORTING GERMINATION TEST RESULTS

REPORT OF GERMINATION TEST OF SEED RECEIVED _.

Test No. Sender's mark Name of seed Duration of

test in days

Germination,

percent

Hard seeds,

percent

CO

to

>

so

a

d

w

>

td

o

o

w

O

O

>

O

ïd

O

d

f

d

td
LIST OF BOTANICAL NAMES

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION

Identification Botanical name Purity Germination

Plate

XXIV, 489

Page

Abutilón theophrasti Medic.- _

Page Page Figure

XXIII 479 Acalypha virginica L _

XXXI, 661 Achillea millefolium L

XXXI 662 Achyrachaena mollis Schauer

XVIII, 353 - 237

238

Adesmia muricata (Jacq.) DC_

Aeschynomene virginica (L.)

BSP.

Aethusa cynapium L__

XVIII, 354

XXV 521

198

200

200

200

201

201

201

Anrovvron. _ _ _ _

I, 13 Agropyron cristatum (L.)

Gaertn.

Agropyron dasystachyum

(Hook.) Scribn.

Agropyron desertorum (Fisch.)

Schult, (formerly A. cristatum).

Agropyron elongatum (Host.)

Beauv.

Agropyron inerme (Scribn. and

Smith) Rydb.

Agropyron intermedium

(Host.) Beauv.

Agropyron pauciflorum (see A,

trachycaulum).

Agropyron repens (L.) Beauv_

55 126

I. 14 ___ „ _-_ 55 126

I, 12

I, 15

I, 9 -_ 201

200

201

200

200

200

200

Agropyron riparium Scribn.

and Smith.

Agropyron smithii Rydb

Agropyron smithii var. molle

(Scribn. and Smith) Jones.

Agropyron suhsecundum

(Link) Hitchc.

Agropyron trachycaulum (Link)

'Maite.

Agropyron trichophorum (Link)

Rieht.

Aarostem,ma oithaao L

I, 10 55 126

I, 11 55 126

I, 16

XV, 273

196

197

198

198

198

198

198

198

196

198

198

197

201

Agrostis ~

I, 1 Agrostis alha L _ _ _ 55

55

126

1,5 Agrostis canina L _ _ 126

I, 6 _ Agrostis elliottiana SchultI, 3-4 Agrostis exarata Trin

I, 7 Agrostis hiemalis (Walt.) BSPAgrostis palustris Huds

Agrostis scahra Willd

55 126

I, 8 _ _ __

I, 2 Agrostis tenuis Sibth 55 126

Hort vars : Colonial bentAstoria. _ _-_

Highland

Aira

Aira c apillaris (see A,

elegans).

I, 18 201 Aira caryophyllea L

I, 17 __ 201 Aira elegans Willd. ex Gaudin.

Aira spp. (see Deschampsia

spp.)

XV, 271 Aizoaceae

373
374 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXVIII, 586

Page

Ajuga chamaepitys (L.) Schreb,

Alhagi camelorum Fisch, (see

A. pseudalhagi).

Alhagi pseudalhagi (Bieb.)

Desv.

Allionia nyctaginea (see Mirabilis nyclaginea).

Allium sppPage Page Figure

XVIII, 355 238

82

82

82

Allium cepa L

Allium porrum L

Allium vineale L

160

160

57

XIII, 220

XXVII, 569 Allocarya sp

202

202

202

202

202

202

Alopecurus

I. 19 Alopecurus aequalis Sobol__

I, 20 Alopecurus carolitiianus Walt

I, 21 Alopecurus geniculatus L

I, 23 Alopecurus myosuroides Huds

I, 22 Alopecurus pratensis L

Alsine graminea (see Stellaria

graminea).

Alsine media (see Stellaria

media).

Althaea hirsuta L

66 126

XXIV, 490

XVIII, 356

XVI, 310

238 Alysicarpus vaginalis (L.) DC.

Alyssum alyssoides L

77 142

XIV-XV, 267-268_ Amaranthaceae

XIV, 2676 Amaranthus alhus L. {A.

graecizans of Am. authors,

not L.)

Amaranthus hlitoides (see A.

graecizans).

XV, 268 Amaranthus graecizans L

XIV, 267a Amaranthus retroflexus L

XXXI, 663 Ambrosia artemisiifolia L

XXXI, 664 Ambrosia psilostachya DC_>

XXXI, 665 Ambrosia trifida L_

XXV, 522 Ammi ma jus L _

XXV, 523 _ Ammi visnaga (L.) Lam

XXVII, 570 Amsinckia intermedia Fisch.

and Mey.

XXVII, 571 Ainsinckia tesselata Gray

XXVI, 541 Anagallis arvensis L_

202 AndropoqonAndropogon furcatus (see A.

gerardi).

Andropogon gerardi Vitman

Andropogon hallii Hack

Andropogon intermedius R. Br„

11,25

II, 26

II, 29

203

203

203

203

203

203

203

203

57

57

126

126

II, 28 Andropogon ischaemum L

II, 30 Andropogon nodosus (Willem.)

Nash.

II, 31 Andropogon sericeus R. Br _

11,27

II, 32

Andropogon scoparius Michx__

Andropogon virginicus L__ _

57 126

XVI, 294 Anemone canadensis L

XXXI, 666 __ _ Anthémis arvensis L

XXXI, 667 _ - Anthémis cotula L _ _

XXXI, 668 Anthémis tinctoria L

203

204

Anthoxanthum

Anthoxanthum aristatum Boiss_
TESTING AGRICULTURAL AND VEGETABLE SEEDS 375

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification Botanical name Purity Germination

Plate

11, 33

Page

204

238

Anthoxanthum odoratum L

Anthriscus sylvestris (L.)

Hoffm.

Anthyllis vulneraria L

Page

66

Page

126

Figure

XXV, 524__.

XVIII, 357

Apargia spp. (see Leontodón)

II, 34 204 Apera spica-venti (L.) Beauv

XXV, 525 Apium ammi (L.) Urban

Apium grav^olens var. dulce

(MilL) Pers.

Apium graveolens var. rapaceum DC.

Apium petroselinum (see

Petroselinum crispum).

Apium segetum (L.) Dumort

80

80

167

167

XXV, 526

XXXI, 669 Aplopappus ciliatus (Nutt.)

XXVI, 542-543-__ Apocvnaceae. _

XXVI, 542 Apocynum androsaemifolium L.

XXVI, 543 Apocynum cannabinum L

XVI, 311___. Arahis glabra (L.) Benth

Arachis huinonnpn TJ 73 142 XXXI, 670 Arctium lappa L

XV, 276 Arenaria serpyllifolia L

1,24 204 Aristida dichotoma Michx

XXXI, 671 Arnoseris minima (L.) Schweigger and Koerte.

Arrhenatherum elatius (L.)

Presl.

Asclepiadaceae

II, 35 205 66 126

XXVI, 544-548___

XXVI, 545 Asclepias galioides HBK

XXVI, 544 Asclepias mexicana Cav

XXVI, 546 Asclepias syriaca L

XXVI, 547 Asclepias tuberosa L

Asparagus offlcinalis L

Asperugo procumbens L

82 160 XXVII, 572

238

239

239

239

239

239

239

AstragalusXViii, 358 Astragalus chinensis L. f

XVIII, 359 Astragalus cicer L

XVIII, 360 Astragalus falcatus Lam

XVIII, 361 Astragalus flexuosus DougL _

XVIII, 362 Astragalus nuttallianus DC_

XVIII, 363 Astragalus rubyi Greene and

Morris.

Atriplex patula var. hastata

(L.) Gray.

Atriplex rosea L

Atriplex truncata Gray

XIV, 246

XIV, 247

XIV, 248

205

207

207

207

207

207

208

208

208

208

A.vena

if, 40 Avena barbata Brot

II, 37 Avena byzantina E. Koch

Avena fatua L

57 "~Í26~ II, 39___

II, 38 Avena (homozygous fatucid)

II, 36 Avena sativa L 57 "126" 35 II, 41 Avena strigosa Schreb

Axßnopus

íí, 42 Axonopus afinis Chase

Axonopus compressas (Swartz)

Beauv.

Axijris amaranthoides L

58 ""Í26" II, 43

XIV, 249
376 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXVTTT 587

Page

Ballota nigra L

Page Page Figure

Barbarea barbarea (see B.

vulgaris).

Barbarea praecox (see B. verna)-

WT ^l2 Barbarea verna (Mill.) Aschers- J^k. V 1, Ol^ Barharea vulaaris R. Br

Barkhausia setosa (see Crépis

setosa).

Bassia hyssopifolia (Pall.)

Ktze.

Beckmannia erucaeformis

(see B. syzigachne).

Beckmannia sy zigachne

(Steud.) Fernald.

Berteroa incana (L.) DC

Al VTVV 9 Pin , ^ov

TTil, ^^AA 208

A.V1, Oi'x

Beta vulgaris L

Beta vulgaris var. cicla

Beta vulgaris var. saccharifera^ _

Boerhaavia erecta L

84

84

84

107

107

107

24,25

W 9fiQ

wv f=;in Boisduvalia densiflora (Lindl.)

Wats.

Boisduvalia stricta (Gray)

Greene.

T^nrii crin fl PPfLP

JvA-V, oiu

AA.V, "Vw oil p;i 1

XXVII-XXVIII,

569-580.

209

209

209

209

234

Bouteloua -- -

ii 46 -

Bouteloua curtipendula

(Michx.) Torr.

Bouteloua gracilis (HBK)

Lag. ex. Steud.

fíñuteloua hirsuta Lag

57

57

126

126 II 47

TT AQ. il, 4o

Brassica^

Brassica adpressa (see Hirschfeldia incana).

Brassica alba Moench (see B.

hirta).

Brassica arvensis (L.) Rabenh.

(see B. kaber),

Brassica campestris L

Brassica campestris var. sarson Prain.

Brassica campestris vars

Brassica chinensis L

XVI, 315 -- 235

234

235

235

234

235

235

234

234

234

234

235

234

83 119

83

83

83

83

119

119

119

119

Brassica hirta Moench

Brassica júncea (L.) Coss

Brassica kaber (DC.) L. C.

Wheeler.

Brassica napus var. annua

Koch.

Brassica napus var. biennis

(Schubl. and Mart.) Reichb.

Brassica napus var. napobrassica (L.) Reichb.

Brassica napus var. pabularia (DC.) Reichb.

Brassica nigra (L.) Koch

Brassica olerácea L _

XVII, 316

XVII, 317

83

83

83

119

119

119

XVII, 318

XVII, 319 83 119

Brassica olerácea var. acephala DC.

83 119
TESTING AGRICULTURAL AND VEGETABLE SEEDS 377

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity' Germination

Plate Page

Brassica olerácea var. hotrytis L.

Brassica olerácea var. capitata L.

Brassica olerácea var. gemmifera Zenker.

Brassica olerácea var. gongylodes L.

Brassica pekinensis (Lour.)

Rupr.

Brassica perviridis Bailey

Brassica rapa L _

Page

83

83

83

83

83

83

83

Page

119

119

119

119

119

119

119

Figure

31

235

235

235

235 Brassica tournefortii Gouan

Brassica spp 83 119

XXXI, 672 Brauneria angustifolia (DC.)

Heller.

Brodiaea coronaria (Salisb.)

Jeps.

Brodiaea grandiflora Lindl

XIII, 221

XIII, 222

209 Bromus

Bromus hreviaristatus Buck!

Bromus carinatus Hook, and

Arn.

Bromus catharticus Vahl

Bromus commutatus Schrad

60

210

210

211

210

III 56___ __ 59 126

III, 52

Bromus commutatus var. apricorum Simonkai.

Bromus hordeaceus (see B.

mollis).

Bromus inermis Leyss

Bromus japonicus Thunb

III, 55 210

211

210

211

59 126

III, 51

III, 57 Bromus marginatus Nees

Bromus mollis L_

59 126

III, 54

Bromus polyanthus Scribn

Bromus rigidus Roth _

60

211

210

211

210

211

210

208

Bromus ruhens L

III, 53 Bromus secalinus L _ _ _

Bromus secalinus var. velutinus

(Schrad.) Koch.

III, 50 Bromus sterilis L

111,49 Bromus tectorum L_ __

II, 45 Buchloë dactyloides (Nutt.)

Engelm.

Bunium hulbocastrum L

67 126

XXV, 527

XXV, 528 Bupleurum protractum Hoffmgg. and Linjî.

XXV, 529 Bupleurum rotundifolium L

XXV, 530 Bupleurum tenuissimum L

Bursa hursa-pastoris (see Capsella hursa-pastoris).

XVII, 320__ Camelina microcarpa Andrz

XVII, 321__. Camelina sativa (L.) Crantz _

XXXI, 659 Campanulaceae

Campe barbarea (see Barbarea

vulgaris).

Campe verna (see Barbarea

verna).

XIII, 225 Cannabinaceae 84

84

167

XIII, 225 Cannabis sativa L 167
378 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXX, 651—

XVII, 322_

XVII, 323_

XXXI, 674__

XXXI, 673__

XXXI, 675__

XXXII, 676_

XII, 204

XII, 205

XXXII, 677_

XXV, 531-

XV-XVI__

XIX, 364-

XIX, 365-

III, 63

XXXII, 678.

XXXII, 679.

XXXII, 680_

XXXII, 681-

XXXII, 682-

XXXII, 683-

XXXII, 684-

XXXII, 685-

XXXII, 686_

XXXII, 687-

XXXI, 655..

XV, 277

XXVI, 532-

XIV, 246-266-

XIV, 251

XIV, 252

XIV, 253

XIV, 254

XIV, 255

XIV, 256_

XIV, 257.

XIV, 258_

Page

237

235

235

235

235

232

239

239

211

III, 59-

211

212

(L.)

Caperonia palustris (L.) St.

Hil.

Caprifoliaceae ._

Capsella bursa-pastoris

Medic.

Capsicum sp

Cardaría

Cardaría draba (L.) Desv

Cardaría draba var. repens

(Schrenk.) O. E. Schulz.

Cardaría pubescens (C. A.

Mey.) Rollins.

Carduus acanthoides L

Carduus crispus L

Carduus macrocephalus Desf__

Carduus pycnocephalus L

Carex festucacea Schkuhr

Carex trichocarpa Muhl

Carthamus tínctoríus L __

Carum bulbocastrum (see Bunium bulbocastrum).

Carum carvi L

Caryophyllaceae

Cassia nictitans L

Cassia tora L

Caucalis nodosa (see Torilis

nodosa).

Cenchrus pauciflorus Benth—

Centaurea calcitrapa L

Centaurea cyanus L

Centaurea ibérica Trevir

Centaurea jacea L

Centaurea maculosa Lam

Centaurea melitensis L

Centaurea picris Pall ---

Centaurea repens (see C. picris).

Centaurea scabiosa L

Centaurea solstitialis L

Centromadia sp

Cephalaria transylvanica (L.)

Schrad.

Cerastium vulgatum L

Chaerophyllum sp

Chamomilla inodora (see Matricaría inodora).

Cheirinia spp. (see Erysimum

spp.) ^.

Chenopodiaceae

Chenopodium album L

Chenopodium berlandieri Moq.

Chenopodium hircinum Schrad

Chenopodium hybridum L

Chenopodium hybridum var.

gigantospermum (Aellen)

Rouleau.

Chenopodium leptophyllum

Nutt.

Chenopodium murale L

Chenopodium rubrum L

Chloris ^—^

Chloris acicularis Lindl

Page Page

80 167

Figure

84 107
TESTING AGRICULTURAL AND VEGETABLE SEEDS 379

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification Botanical name Purity Germination

Plate

III, 58

Page

212

212

212

Chloris divaricata R. Br_

Page Page Figure

III, 60__ Chloris gayana Kuntli

Chloris virgata Swartz.

66 126

XXXII, 688 Chondrilla júncea L

XVII, 324 236 Chorispora ten ell a (Willd.)

DC.

Chrysanthemum leucanthemum

L.

Cicer arietinum L_

XXXII, 689

XIX, 366 239 73

84

84

142

113

113

Cichorium endivia L

XXXII, 690 Cichorium intybus L

XXVI, 533 Cicuta maculata L_ _

XXXII, 691 Cirsium arvense (L.) Scop

Cirsium lanceolatum Scop.

(see C. vulgäre).

XXXII, 692 Cirsium vulgäre (Savi) Tenore

Citrullus vulgaris Schrad

Clinopodium (see Satureja)

82 124

XXVII, 563 Collomia gracilis Dougl

XXVII, 564 Collomia grandiflora Dougl

XII, 215 Commelina communis L

XII, 215-216 Commelinaceae

XXXI-XXXIV, Compositae_ __ 84 113

661-735.

XXVI, 534 Conium maculatum L

XVII, 325 236

258

258

258

258

Conringia orientalis (L.)

Dumort.

XXVI-XXVII, Convolvulaceae

549-562.

Convolvulus

XXVI, 549 Convolvulus arvensis L_

XXVI, 550 Convolvulus sepium L_ _

XIV, 259 Corispermum hyssopifolium L _

XIV, 260 Corispermum villosum Rydb

XIX, 367 240

239

236

212

Coronilla scorpioides Koch

XIX, 368 Coronilla varia L_

Coronopus didymus (L.) Sm

III, 61 Corynephorus canescens (L.)

Beauv.

XXXII, 693a Crépis capillaris (L.) Wallr

XXXII, 6936 Crépis setosaHall

Crépis virens (L.) (see C.

capillaris).

240 Crotalaria

240

240

240

240

240

240

XIX, 369 Crotalaria intermedia Kotschy_

Crotalaria júncea L

______

74

74

74

74

"Í42"

142

142

142

142

XIX, 370

XIX, 371

XIX, 372

Crotalaria lanceolata E. Mey__

Crotalaria mucronata Desv

Crotalaria spectabilis Roth____

Crotalaria striata DC. (see C.

mucronata).

Crotón sp _

56

XXIII, 480

XVI-XVIII, 310- 233 Cruciferae_ 83

82

82

82

82

119

124

124

124

124

344.

Cucumis melo L

Cucumis sativus L " "~34

Cucúrbita maxima Duchesne _ _

Cucúrbita moschata Duchesne._
380 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXVII, 558_

XXVII, 557 _

XXVII, 562_

XXVII, 559_

XXVII, 560_

XXVII, 556_

XXVII, 561.

XIX, 373_

XIV, 261.

Ill, 62_

III, 64

III, 65

XII, 204-214.

XII, 206

XII, 207

III, 66

III, 67-68__

XXIX, 612.

XIX, 374_.

XXVI, 535_

XVI, 295___

XVI, 296___

III, 69

III, 70-

XIX, 375_

XV, 278____

XXVI, 551-

IV, 73

IV, 74

IV, 75

XXX, 645

XXX, 646

XXXI, 655-658_

XXXI, 656

Page

259

260

260

260

260

260

260

260

240

212

213

213

213

213

240

213

213

241

214

III, 72_

III, 71_

214

214

Cucúrbita pepo L

Cucurbitaceae

Cuscuta

Cuscuta epilinum Weihe

Cuscuta epithymum Murr

Cuscuta gronovii Willd

Cuscuta indecora Choisy

Cuscuta pentágona Engelm

Cuscuta planiflora Tenore_

Cuscuta racemosa var. chiliana

Engelm.

Cyamopsis tetragonolohus (L.)

Taub.

Cycloloma atriplicifolium

(Spreng.) Coult.

Cynara cardunculus L

Cynara scolymus L

Cynodon dactylon (L.) Pers

Cynosurus

Cynosurus cristatus L

Cynosurus echinatus L

Cyperaceae

Cyperus esculentus L

Cyperus rotundus L

Cyperus spj)

Dactylis glomerata L

Danthonia spicata (L.) Beauv_-

Datura strarnonium L

Dauhentonia texana Pierce

Daucus carota L

Delphinium consolida L

Delphinium menziesii Hook—

Deschampsia caespitosa (L.)

Beauv.

Deschampsia flexuosa (L.)

Trin.

Desmodium tortuosum (Sev.)

DC.

Dianthus armeria L

Dichondra repens Forst

Digilaria filiformis (L.) Koel-.

Digitaria ischaemum (Schreb.)

Schreb. ex Muhl.

Digitaria sanguinalis (L.) Scop

Diodia teres Walt

Diodia virginiana L

Dipsacaceae

Dipsacus sylvestris Huds

Distichlis

Distichlis dentata (see D.

stricta).

Distichlis spicata (L.) Greene. _

Distichlis stricta (Torr.) Rydb.

Dondia depressa (see Suaeda

Page

82

82

Page

124

124

84

84

60

113

113

126

60 126

60 126

Figure

30

80

74

Downingia spp. Nutt

Dracocephalum parviflorum (see

Moldávica parviflora).

167

142

61

56
TESTING AGRICULTURAL AND VEGETABLE SEEDS 381

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification Botanical name Purity Germination

Plate Page

Echinacea angustifolia (see

Brauneria angustifolia).

Echinochloa^

Page Page Figure

214

214

214

214

IV, 76 Echinochloa colonum (L.) Link_

Echinochloa crusgalli (L.)

Beauv.

Echinochloa crusgalli var. frumentacea (Roxb.) W. F.

Wight.

Echiurn vulgäre L

IV, 77

IV, 78 65 126

XXVII, 573

XII, 208 Eleocharis obtusa (Willd.)

Schultes.

Eleocharis tenuis (Willd.)

Schultes.

Eleusine coracana (L.) Gaertn_

Eleusine indica (L.) Gaertn

XII, 209

IV, 79

IV, 80

IV, 81-84 214

215

215

215

215

215

215

Elymus

IV, 81 Elymus canadensis L 55 126 IV, 82 Elymus glaucus Buckl

IV, 83 Elymus junceus Fisch

Elymus riparius Wiegand

Elymus triticoides Buckl

IV, 84 Elymus virginicus L_

Elymus spp 55

215 Eragrostis

Eragrostis abyssinica (Jacq.)

Link. (seeE, tef).

Eragrostis capillaris (L.) Nees_

Eragrostis chloromelas Steud

IV, 85„__ 216

216

216

216

216

216

216

IV, 87

IV, 86 Eragrostis cilianensis (All.)

Lutati.

Eragrostis curvula (Schrad.)

Nees.

Eragrostis lehmanniana Nees

IV, 88 66 126

IV, 89

Eragrostis tef (Zuccagni) Trotter.

Eragrostis trichodes (Nutt.)

Erechtites hieracifolia (L.) Raf_

Erechtites prenanthoides DC

IV, 90

XXXII, 694

XXXII, 695

XXIII, 481 Eremocarpus setigerus Benth

IV, 91 Eremochloa ophiuroides (Munro)

Hack.

XXXII, 696 Erigeron annuus (L.) Pers

XXXII, 697__ Erigeron canadensis L

IV, 92 Eriochloa punctata (L.) Desv

Eriocorna cuspidata (see Oryzopsis hymenoides).

Er odium cicutarium (L.) L'Her_

Eruca sativa Mill

XXIII, 469__, _

XVII, 326__.. ~236"

82 167

XVII, 327 Erysimum asperum (Nutt.)

XVII, 328 Erysimum cheiranthoides L_

XVII, 329 Erysimum inconspicuum (S.

Wats.) Mac M.

Erysimum officinale (see Sisymbrium officinale).

Erysimum parviflorum (see E.

. inconspicuum).

957116—52- -26
382 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification

Plate

XVI, 305

XXIII-XXIV,

479-488.

XXIII, 482

XXIV, 484

XXIII, 483

XXIV, 485

XXIV, 486

XXIV, 487

Page

XXIV, 488_

XXIX, 623_

XXVI, 536_

IV, 94 _

IV, 93.

IV, 96_

IV, 95_

XII, 210_

XII, 211-

XXXII, 698-

XXXII, 699_

XVI, 309

XIX, 376

XXVIII, 588-

XXVIII, 589 _

XXXIII, 700-

XXX, 647___-

XXX, 648-__-

V, 97

XXV, 512__

XXV, 513-

XXV, 514__

XXV, 515_-

XXIII, 469-

XXIII, 470_

XXIII, 471_

XXIII, 472_

XXIII, 473_

XXIII, 474.

XVIII, 346_

XXVII, 565

216

218

218

218

218

217

218

217

217

217

217

217

217

241

474_

Botanical name Purity

Eschscholtzia californica Cham.

Euphorbiaceae

Page

Euphorbia corollata L

Euphorbia dentata Michx

Euphorbia esula L_____

Euphorbia helioscopia L

Euphorbia margincia Pursh___

Euphorbia nutans Lag

Eiiphorbia preslii Guss, (see

E. nutans).

Euphorbia supina Raf

Euphrasia sp

Fagopyrum esculentum Moench__

Falcaria rivini Host .- 7 - -

Falc atula ornithopodioides

(DC.) Wilmott (see Trifolium ornithopodioides).

Festuca (fine-leaved)

Festuca (tall)

Fertuca arundinacea Schreb—

Hort. vars. : Alta

Ky-3]

Festuca capillata Lam

Festuca elatior L

Festuca megalura

Festuca myuros L

Festuca octoflora

Festuca ovina L

Festuca rubra L

Festuca rubra var. commutata

Gaud.

Fimbristylis autumnalis (L.)

R and S.

Fimbristylis baldwiniana

(Schulter) Torr.

Fimbristylis laxa (see F. baldwiniana) .

Franseria discolor Nutt

Franseria tenuijolia Torr, and

Gray.

Fumaria officinalis L

Galega oßcinalis L

Galeopsis ladanum L

Galeopsis tetrahit L

Galinsoga parviflora Cav

Galium aparine L

Galium mollugo L

Gastridium ventricosum

(Gouan.) Schinz. and Thell.

Gaura coccinea Pursh

Gaura odorata Sesse

Gaura sinuata Nutt

Gaura villosa Torr

Geraniaceae

Geranium carolinianum. L

Geranium columbinum L

Geranium dissectum L

Geranium molle L

Geranium pusillum L

Geum sp . Gilia capitata Hook

81

61

61

61

Germination

Page

167

126

Figure

61

61

61

126

126

126

126

126

82
TESTING AGRICULTURAL AND VEGETABLE SEEDS 383

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XVI, 306..._-

V, 98

V, 99

V, 100

XIX, 377_-_

XXV, 516„-.

XXVI, 548-.

Page

I-XII, 1-203 (see

fig. 63).

XXXIII, 701

V, 101.

XIV, 263_

XXVIII, 590_

XIX, 378

XXXIII, 702_

XXXIII, 703..

XXVII, 574__

XXVII, 575 _

XXXIII, 704_

XXXIII, 705_

XXIV, 491___

XXXIII, 706_

XVII, 330

XIX, 379 _

V, 102

V, 103_-..

V, 106-

V, 107-

V, 108 _

V, 105-

V, 104-

XXX, 649___

XXVII, 568-

XXIX, 613___

XXIV, 504.--

XXIV, 504___

XXXIII, 707-

XIX, 380

XXVI, 552-

241

195

241

241

218

219

219

219

219

218

242

258

259

259

Glaucium corniculatum Curt__

Glyceria fluitans (L.) R. Br—

Glyceria grandis S. Wats

Glyceria striata (Lam.)Hitchc_

Glycine max (L.) Merr

Godetia tenella (Cw.) S. Wats_

Gonolobus laevis Michx

Gossypium spp

Gramineae

Grindelia squarrosa (Pursh.)

DunaL

Hackelochloa granularis (L.)

Kuntze.

Halogeton glomeratus C. A.

Mey.

Hedeoma pulegioides (L.) PersHedysarum coronarium L

Helianthus annuus L

Helianthus ciliaris DC

Heliotropium curassavicum L__

Heliotropium europaeum L

Hemizonia luzulaefolia DC

Heterotheca grandiflora Nutt_-

Hihiscus esculentus L

Hibiscus trionum L

Hieracium auraniiacum L

Hirschfeldia incana (L.) Lagreze-Fossat.

Hoffmannseggia sp

Holcus lanatus L

Holcus mollis L__

Hookera coronaria (see Brodiaea coronaria).

Hookera douglasii (see Brodiaea grandiflora).

Hordeum

Hordeum brachyantherum Nevski.

Hordeum jubatum L

Hordeum leporinum Link

Hordeum murinum (see H.

leporinum).

Hordeum nodosum (see H.

brachyantherum).

Hordeum pusillum Niitt

Hordeum vulgäre L

Hosackia americana (see Lotus

purshianus).

Houstonia purpurea L

Hydrophyllaceae .

Hymenophysa pubescens of Am.

auth. (see Cardaria pubescens) .

Hyoscyamus niger L

Hypericaceae

Hypericiim perforatum L

Hypochaeris radicata L

Indigofera hirsuta L

Ipomoea

Ipomoea hederacea (L.) Jacq_-

Ipomoea lacunosa L

Page Page Figure

73 142

81

55

164

126

84 113

81 164

66

62

126

126

50

59

60
384 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXVI, 554

XXVI, 553

XIII, 224

Page

258

259

XXXIII, 708

XXXIII, 709

XXXIII, 710

XXVI, 555

XII, 217-219

259

XII, 219

XXIX, 624

XIV, 264 _

XII, 212

XXVIII-XXIX,

586-611.

XXXIII, 711

XXXIII, 713

XXXIII, 712

XXVIII, 591

XXVII, 576

XXVII, 577

XXXIII, 714

242

243

242

XIX, 381

XIX, 382

242

243

243

243

243

XIX, 383

XIX, 384

XIX, 385

XVIII-XXIII,

353-468.

XXXIII, 715

XXXIII, 716

243

243

243

237

XXVIII, 592

XVII, 331 236

Ipomoea pandurata (L.) G. F.

W. Mey.

Ipomoea purpurea (L.) Iloth__

Iridaceae

Iva axillaris Pursh

Iva ciliata Willd

Iva xanthifolia Nutt

Jacquemontia tamnifolia (L.)

Griseb.

Juncaceae

Juncoides campestre (see

Luzula campestris).

Juncoides nemorosum (see

Luzula luzuloides).

Juncus tenuis Willd

Juncus spp

Kickxia spuria (L.) Dumort_„

Knautia arvensis (see Scabiosa

arvensis).

Kochia hyssopifolia (see

Bassia hyssopifolia).

Kochia scoparia (L.) Roth

Koellia sp. (see Pycnanthemum

sp.).

Kyllinga sp

Labiatae

Page Page

56

Lactuca canadensis L

Lactuca pulchella (Pursh.) DC.

Lactuca sativa L 84 113

Lactuca scariola var. integrifolia (Bogenh.) G. Beck.

Lamium amplexicaule L

Lappula echinata Gilib

Lappula lappula (see L.

echinata).

Lappula occidentalis (S. Wats.)

Greene.

Lapsana communis L

Lathyrus

Lathyrus angulatus L

Lathyrus annuus L.

Lathyrus aphaca L

Lathyrus hirsutus L

Lathyrus pusillus EU

Lathyrus stipularis Presl

Lathyrus sphaericus Retz

Lathyrus sylvestris L

Lathyrus tingitanus L

Lathyrus tuberosus L

Leguminosae

74 142

73 142

Leontodón autumnalis L__

Leontodón nudicaulis L

Leonurus cardiaca L

Lepidium apetalum (see

densiflorum).

Lepidium campestre (L.) R. Br.

L.

Figure

27, 28,

29
TESTING AGRICULTURAL AND VEGETABLE SEEDS 385

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XVII, 332

Page

Lepidium densiflorum Schrad

Page Page Figure

Lepidium draha (see Cardaría

draba).

XVII, 333 237 Lepidium latifolium L _

Lepidium sativum L 83 119

XVII, 334 Lepidium virginicum L„

V, 109 219

243

244

244

244

244

244

244

Leptoloma cognatum (Schult.)

Chase.

Lespedeza

Lespedeza bicolor Turcz

XX, 389___ Lespedeza cuneaia (Dumont)

G. Don.

Lespedeza hedysaroides (Pallas)

Ricker.

Lespedeza stipulacea Maxim

Lespedeza striata (Thunb.) H.

and A.

Lespedeza striata Hort. var.

Kobe.

Liliaceae

74

'74

74

74

74

82

81

142

142

142

142

142

160

162

XX, 388

XIX, 386

XIX, 387

XIII, 220-223

XXIII, 476-477___ Linaceae _

Linaria spuria (see Kickxia

spuria).

XXIX, 625 Linaria vulgaris Hill

XXIII, 476 Linum usitatissimum L

Linum virginianum L_

81 162 58

XXIII, 477

XXVIII, 581 Lippia nodiflora Michx

XXVII, 578 Lithospermum arvense L

XXIV-XXV, Loasaceae

506-508.

XXXI, 660 Lobeliaceae

XXXI, 660 Lobelia inflata L

Lobelia sp

219

220

220

220

220

220

245

Lolium

V, 111 Lolium multiflorum Lam

Lolium perenne L

64

64

126

V, 110 126

V, 112 Lolium persicum Boiss. and

Hohen.

Lolium rigidum Gaud

V, 113 Lolium temulentum L

Lotus

Lotus americanus (see L.

purshianus).

XX, 390 245 Lotus angustissimus

245

245

XX, 391 Lotus corniculatus L 75 142 54 55

XX, 392 Lotus hispidus Desf

Lotus major Sm. not Scop, (see

L. uliginosus).

Lotus purshianus (Benth.)

Clements and Clements.

Lotus uliginosus Schkuhr

Lotus uliginosus var. villosus.

XX, 393 245

245

245

245

245

75 142

XX, 394

XX, 395 Lotus uliginosus var, glabriusculus.

Lotus spp

XXV, 517 Ludwigia alternifolia L

245

246

246

246

Lupinus^-

Lupinus albus L 73

73

73

142

142

142

XX, 396_ Lupinus angustifolius L

Lupinus luteus L

"5Í,"52

XX, 397

XII, 217 Luzula campestris (L.) DC
386 AGRICULTÜHE HANDBOOK NO. 3 0, Ü. S. DEM. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name

Plate

XII, 218

XV, 279_

XV, 280_

XXVIII, 593__-

XXV, 509

XXV, 509

XXXIII, 717___

XXXIII, 718__-

XXIV, 492

XXIV, 493

XXIV, 494

XXIV, 495

XXIV, 489-502.

XXIV, 496_

XXVIII, 594 _

XXXIII, 719_

XX, 398_

XX, 399-

XX, 400 _

XX, 401 _

XX, 402 _

XX, 403 _

XXIX, 626_

XX, 404

XX, 406

XX, 405

V, 114

XXIV, 503__.

XXVIII, 595_

XXIV, 506___

XXTV, 507__-

XXV, 508

XV, 270.

XXVIII, 596_

V, 115

XIII, 223

XXVII, 579 _.

V, 116

Page

232

232

232

246

246

246

247

247

247

247

247

247

248

247

XXVII, 566-

220

Luzula luzuloides (Lam.)

Dandy and Wilmott.

Lychnis

Lychnis alba Mill

Lychnis dioica L

Lycopersicon esculentum Mill__

Lycopus virginicus L

Lythraceae

Lythrum hyssopifolia L

Madia glomerata Hllk

Madia sativa Molina

Malva moschata L

Malva parviflora L

Malva rotundifolia L

Malva sylvestris L

Malvaceae

Malvastrum americanum (see

M. coromandelianum).

Malvastrum angustum (see

Sidopsis hispida).

Malvastrum coromandelianum

(L.) Garcke.

Malvastrum tricuspidatum (see

M. coromandelianum).

Marruhium vulgäre L

Matricaria inodora L

MedicagoMedicago arabica (L.) Huds—

Medicago hispida Gaertn

Medicago lupulina L

Medicago orbicularis (L.) All__

Medicago sativa L

Medicago tubercuLata Willd

Meibomia purpurea (see Desmodium tortuosum).

Meibomia tortuosa (see Desmedium tortuosum).

Melampyrum arvense L

Melilotus

Melilotus alba Desr

Melilotus indica (L.) All

Melilotus officinalis (L.) Lam__

Melinis minutiflora Beauv

Melochia corchorifolia lu

Mentha arvensis L

Mentzelia albicaulis Dougl

Mentzelia dispersa Wats

Mentzelia nuda (Pursh.)

Greene.

Mirabilis nyclaginea (Michx.)

MacM.

Moldávica parviflora Nutt____-

Molinia caerulea (L.) Moench_

Muscari comosum Mill _ .

Myosotis arvensis (L.) Hill

Nassella trichotoma (Ness.)

Hack.

Navarretia intertexta (Benth.)

Hook.

Purity

Page

80

81

77

77

77

77

75

75

75

66

Germination

Page

167

164

142

142

142

142

142

142

142

126

Figure

62

53
TESTING AGRICULTURAL, AND VEGETABLE SEEDS 387

ÍNDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXVII, 567

Page

Navarretia squarrosa (Esch.)

H. and A.

Nepeta cataría L _ __

Page Page Figure

XXVIII, 597

XVII, 335 Neslia paniculata (L.) Desv _

Nicotiana tabacum L 334 349

XVI, 297 NigeUa damescena L

XVI, 298 Niqella sativa L

XV, 269-270 Nyctaginaceae _ _

XXV, 518 Oenothera biennis L _

XXV, 519 Oenothera laciniata Hill _

XXV, 520 Oenothera varodiana Munz

XXV, 510-520 Onagraceae „ _ _

XX, 407- - 248

248

248

Onohrychis viciaefolia Scop

Ononis repens L _

74 142

XX, 408

XX, 409 Ornithopus sativus^hink

V, 117 Oryza sativa L 62

65

65

126

126

126

38

V, 118 Oryzopsis hymenoides (Roem.

and Schult.) Ricker.

Oryzopsis miliacea (L.) Benth.

and Hook.

Oxalidaceae__

V, 119 __

XXIII, 475

XXIII, 475 Oxalis stricta L _ __

Oxyhaphus nyctaginea (see

Mirabilis nyctaginea).

Panicularia americana (see

Olyceria grandis).

Panicularia fluitans (see Glyceria fluitans),

Panicularia nervata (see Glyceria striata).

220 Panicum

221

221

221

221

221

221

221

221

221

221

221

221

222

222

221

221

221

222

VI, 121 Panicum anceps Michx_

VI, 122__ . Panicum antidotale Retz

Panicum bergii Arech

65 126

VI, 123

VI, 124 Panicum brachyanthum Steud_

VI, 125 Panicum capillare L _

VI, 126 Panicum capillare var. occidentale Rydb.

Panicum dichotomiflorum

Michx.

Panicum fasciculatum

Swartz.

Panicum gattingeri Nash

VI, 127

VI, 128 65 126

VI, 129

VI, 130 Panicum hillmani Chase

VI, 131 Panicum huachucae Ashe

VI, 132 Panicum maximum Jacq

Panicum miliaceum L

Panicum obtusum H. B. K

65

65

126

VI, 133 126

VI, 134

VI, 135 Panicum purpurascens Raddi

VI, 136 Panicum ramosum lu 65 126

VI, 137 Panicum texanum Buckl __

VI, 138 Panicum virgatum L 65

65

126

Panicum spp 126

XVI, 307 Papaver somniferum L

XVI, 305-308 Papaveraceae

Parentucellia sp. Viv 56

222

222

222

Paspalum

VII, 13"9" Paspalum boscianum Flügge

VII, 140 Paspalum dilatatum Poir 58 126
388 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

VII, 141

VII, 142

VII, 143

VII, 144

VII, 145

VII, 146

VII, 147

VII, 148

XXX, 632_

VII, 149_

VII, 150.

XXVI, 537.

XXVII, 568_

vii7í5T_'_"r"

VII, 152_

VII, 155-

VII, 153_

VII, 156_

VII, 154_

XX, 410_

XX, 411_

V, 120

XXIX, 614_

XXIX, 615_

XXIX, 616_

XXXIII, 720_

XXXIII, 721.

XXVI, 538._-

XXI, 412

XXVIII, 580-

XXX, 633-644-

XXX, 638

XXX, 636-

XXX, 643.

Page

222

222

222

223

223

222

222

222

223

223

223

223

224

223

223

224

224

224

224

248

248

249

Paspalum distichum L

Paspalum floridanum Michx...

Paspalum laeve Michx

Paspalum malacophyllum Trin.

Paspalum notatum Flügge

Paspalum plicatulum Michx

Paspalum seiaceum Michx

Paspalum urviUei Steud

Pastinaca sativa L

Pedaliaceae

Pennisetum

Pennisetum glaucum (L.) R. Br_

Pennisetum purpureum

Schumach.

Petraselinum crispum (Mill.)

Nym. (see P. hortense).

Petroselinum hortense (see P.

crispum),

Petroselinum segetum (see

Apium segetum).

Phacelia sp

Phalaris

Phalaris augusta Nées, ex

Trin.

Phalaris arundinacea L

Phalaris canariensis L

Phalaris caroliniana Walt

Phalaris minor Retz

Phalaris paradoxa L

Phalaris tuberosa var. stenoptera (Hack.) Hitchc.

Phaseolus angularis (Willd.)

W. F. Wight.

Phaseolus aureus Roxb

Phaseolus coccineus (L.) Willd.

Phaseolus lunatus var. macrocarpus (Benth.) Van Es.

Phaseolus vulgaris L

Phleum pratense L

Physalis lohata Torr

Physalis longifolia Nutt

Physalis puhescens L

Physalis suhglahrata Mackenz.

and Bush.

Picris echioides L

Picris hieracioides L

Pimpinella saxifraga L

Piptochaetium trichotoma (see

Nassella trichotoma).

Pisum sativum L

Pisum sativum var. arvense

(L.) Poir.

Plagiobothrys sp. Fisch, and

Mey.

Plantaginaceae_ .

Plantago arenaria Waldst. and

Kit.

Plantago aristata Michx

Plantago coronopus L

Plantago elongata (see P.

Page Page

58

58

80

62

62

80

60

60

60

73

73

73

73

73

66

80

73

73

126

126

167

126

126

167

126

126

126

142

142

142

142

142

126

167

142

142

Figure

45, 46,

47

44

43

48,49
TESTING AGRICULTURAL AND VEGETABLE SEEDS, 389

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

XXX,

XXX,

XXX,

XXX,

XXX,

XXX,

XXX,

XXX,

XXX,

Plate

642__.

639_-.

633__.

644__.

637_-.

641__.

640-_.

634...

635_..

Page

VIII, 160, X, 17U_

VIII, 159, X, 17lh.

VIII, 161, X, 171/.

VIII, 162, X, 171ör.

VIII, 163

X, 171m

VIII, 164, X, 171d.

X, 17171

X, 171r

X, 1710

IX, 165, X, 1712?-

X, 171i

X, 171g

IX, 166, X, 171c_

IX, 167, X, 171fc_

IX, 168, X, 171eIX, 169, X, 171a_

X, I7li

X, 171s

IX, 170, X, 1716_

X, 171

XXVII, 563-567.

XIII-XIV, 227-

245.

XIII, 227

224

226

226

226

227

227

XIII, 228-

XIII, 229-

XIII, 230-

XIII, 231-

XIII, 232 _

XIII, 234_

XIII, 233-

VIL 157__

XV, 272.___

XV, 272____

XVIII, 347_

XVIII, 348_

XXVI, 541 „

XXVIII, 598-

XXI, 413

XXVIII, 599-

225

226

226

226

226

226

226

226

226

227

225

227

225

249

Plantag0 hirtella H. B. K

Plantago lanceolata L

Plantago major L

Plantago ovata Forsk

Plantago psyllium L

Plantago pusilla Nutt

Plantago rhodosperma Dcne_

Plantago rugelii Dene

Plantago virginica L

Poa,

Poa ampia Merr

Poa annua L

Poa arachnifera Torr

Poa arida Vasey

Poa bulbosa L

Poa canbyi (Scribn.) Piper

Poa compressa L

Poa cusickii Vasey

Poafendleriana (Steud.) Vasey.

Poa glaucifolia Scribn. and

WilL

Poa interior Rydb

Poa juncifolia Scribn

Poa longiligula Scribn. and

WilL

Poa nemoralis L

Poa nevadensis Vasey ex Scribn,

Poa palustris L

Poa pratensis L

Poa secunda Presl

Poa stenantha Trin

Poa trivialis L

Poa spp. (paleas)

Polemoniaceae

Polygonaceae

Page

67

67

67

67

67

67

Page

126

126

126

126

126

126

Polygonum argyrocoleon Steud.

ex Kunze.

Polygonum aviculare L

Polygonum aviculare (Cleistogenes).

Polygonum convolvulus L

Polygonum hydropiper L

Polygonum lapathifolium L

Polygonum pensylvanicum L__.

Polygonum persicaria L

Polypogon monspeliensis (L.)

Desf.

Portulaca olerácea L

Portulacaceae_ - —

Potentilla canadensis L

Potentilla monspeliensis L

Primulaceae

Prionopsis ciliata (see Aplopappus ciliatus).

Prunella vulgaris L —

Pueraria thunbergiana (Sieb.

and Zuce.) Benth.

Pycnanthemum sp - Quincula labata (see Physalis

lobato).

67

67

81

74

Figure

126

126

167

142
390 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate Page

Raimannia laciniata (see Oenothera laciniata).

Ranunculaceae.

Page Page Figure

XVI, 294-304

XVI, 299 Ranunculus acris L_

XVI, 300 Ranunculus hulhosus L _

XVI, 301 Ranunculus parviflorus L _

Ranunculus parvulus (see R.

sardous).

XVI, 302 Ranunculus repens L _

XVI, 303 Ranunculus sardous Crantz

XVII, 336 Raphanus raphanistrum L

XVII, 337 Raphanus sativus L 83 119 32,33

XVII, 338 Rapistrum rugosum (L.) All__

XXXIII, 722 Ratibida columnaris (Sims.)

D. Don.

XVIII, 345 Reseda lutea L___ _

XVIII, 345 Resedaceae. __ _

Rheum rhaponticum L

Rhynchospora macrostachya

Torr.

Roemeria refracta DC

81 167

XII, 213

XVI, 308

XVII, 339 237 Rorippa austríaca (Crantz.)

Bess.

Rorippa nasturtium-aquaticum

(L.) Britt. and Rendle.

Rorippa sylvestris (L.) Bess__

83 119

XVIII, 340 237

XVIII, 349 Rosa sp

XVIII, 346-352___ Rosaceae_ __ _ _ __

XIV, 265 Rouhieva multifida (L.) Moq_

XXX, 645-650____ Rubiaceae _ __ __ _

XVIII, 350 Ruhus sp_ - _

XXXIII, 723 Rudheckia hirta L

XIII, 235 Rumex acetosa lu 81 167

XIII, 236 Rumex acetosella L

XIII, 237 Rumex altissimus Wood

XIII, 238 Rumex conglomeratus Murr

XIII, 239 ._ Rumex crispus L __ __

XIII, 240 Rumex ohtusifolius L

XIII, 241 Rumex occidentalis Wats

XIII, 242 Rumex persicarioides L

XIII, 243 Rumex pulcher L _ _

XIV, 244 Rumex salicifolius Weinm___

XIV, 245 Rumex venosus Pursh

XIV, 266 Salsola kali var. tenuifolia

Tausch.

Salvia lanceaefolia (see S.

lanceolata).

XXVIII, 600 Salvia lanceolata Willd

XXVIII, 601 Sahia verticillata L _

XVIII, 351 Sanguisorba annua Nutt___ _

XVm, 352__ Sanquisorba minor Scop_

XV, 281 Saponaria vaccaria L _ _

XXVIII, 602 Satureja acinos (L.) Scheele

XXVIII, 603-___. Satureja nepeta (L.) Scheele __

XXIX, 604 Satureja vulgaris (L.) Fritsch,

XXXI, 657 Scabiosa arvensis L

XXXI, 658 Scabiosa sp

VII, 158 Schedonnardus paniculatus

(Nutt.) Trel.

XII, 214 Scirpus sp_- __ _ _ __

XV, 282 Scleranthus annuus L ::::::i::::""
TESTING AGRICULTURAL AND VEGETABLE SEEDS 391

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXIX, 627

XXIX-XXX, 623-

631.

XI, 184

XXXIV, 724

XXXIV, 725

XXX, 632

XXI, 414

X, 172_

X, 173-

X, 174_

XI, 180

XI, 182 ___

XI, 181

XI, 183

X, 175

X, 176

X, 177

X, 178

X, 179

XXX, 650_-

XXIV, 497 _

XXIV, 498_

XXIV, 499_

XXIV, 500_

XXIX, 605_

XXIV, 501 _

XV, 283-

XV, 285-

XV, 286-

XV, 287-

XV, 288-

XV, 289_

XV, 290-

Page

249

227

229

228

228

229

229

229

229

229

229

228

228

228

228

232

233

233

233

233

233

232

233

XV, 284-

XV, 291 _ —

XVIII, 341-

XVIII, 342-

XIII, 224--

XXIX, 612-622-

XXIX, 617

XXIX, 618

XXIX, 619-.

XXIX, 620-.

XXIX, 621-.

XXXIv., 726 _

XXXIV, 727-

233

233

'237

Scrophularia marilandica L_

Scrophulariaceae

Page Page

Sécale céréale L

Senecio jacohaea L

Senecio vulgaris L

Sesamum orientale L

Sesbania exáltala (Raf.) Torr-_-

Setaria

Setaria faheri Herrm

Setaria geniculata (Lam.) Beauv_

Setaria grisehachii Fourn

Setaria itálica (L.) Beauv

Hort, vars.: Common

German

Hungarian

White WonderSetaria lutescens (Weigel) HubbSetaria macrostachya H. B. K- _

Setaria magna Griseb

Setaria verticillata (L.) Beauv-_

Setaria viridis (L.) Beauv

Sherardia arvensis L

Sida hederacea (Dougl.) Torr_-

Sida spinosa L

Sidalcea campestris Greene

Sidalcea hendersonii Wats

Sideritis montana L

Sidopsis hispida (Pursh.) Rybd_

Silène.

Silène anglica Am. auth., not

L. (see S. gallica).

Silène antirrhina L

Silène cónica L

Silène conoidea L

Silène crética L

Silène cserei Baumg

Silène cucuhalus Wibel

Silène dichotoma Ehrh

Silène fabaria Rydb. (see S.

cserei).

Silène gallica L

Silène latifolia (see S. cucuhalus) .

Silène noctiflora L

Sisymhrium altissimum L

Sisymhrium irio L

Sisymhrium officinale (L.) Scop.

Sisyrinchium sp— -

Soja max (see Glycine max) —

Solanaceae

Solanum carolinense^ L

Solanum elaeagnifolium Cav_-_

Solanum melongena var. esculentum Nées.

Solanum nigrum L

Solanum rostratum Dunal

Solanum triflorum Nutt

Sonchus arvensis L

Sonchus asper (L.) Hill

62 126

74 142

65 126

Figure

36,37

80

80

167

167
392 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXXIV, 728-

XI, 185-

XI, 187-

XI, 186-

XI, 188 _

XI, 189-

XI, 193-

XI, 192-

XI, 191-

XI, 190-

XI, 194-

XXXI, 659_

XVI, 292___

XVI, 293—

XXIV, 502-

XII, 196-

XII, 197-

XII, 198-..

XXIX, 606_

XXIX, 607_

XV, 274____

XV, 275_.-.

XXIV, 503.

XI, 195

XXI, 415--

XXIX, 622-

XXI, 416-_

XIV, 262_

XXI, 417.

XXX, 651-

XXXIV, 729-

XXXIV, 731-

XXXIV, 730-

XVIII, 343--.

XXIX, 608-_.

XXIX, 609--.

XVI, 304

XXXIV, 732 _

XVIII, 344__.

XXVI, 539.--

Page

229

230

230

230

230

230

230

230

230

230

230

230

231

231

231

231

231

249

249

250

Sonchus oleraceus L

Sorghastrum nuians (L.) Nash_.

Sorghum

Sorghum halepense (L.) Pers...

Sorghum (Sorghum-Sudan hybrids).

Sorghum sudanense (Piper)

Stopf. {S. vulgäre var.

sudanense Hitchc.)

Sorghum vulgäre Pers

Hort. vars. : Black Amber

Sumac

Feterita...

Hegari

Kafir

Milo

Sorghum vulgäre var. technicum (L.) BoerL

Specularia perfoliata (L.) A.

DC.

Spergula arvensis L

Spergula pentandra L

Sphaeralcea coccínea (Pursh.)

Rydb.

Spinacia olerácea L

Sporoholus

Sporobolus airaides Torr

Sporobolus clandestinus (Bieter.) Hitchc.

Sporobolus cryptandrus (Torr.)

Gray.

Sporobolus neglectus Nash

Stachys annua L

Stachys palustris L

Stellaria gramínea L

Stellaria media (L.) Cyrill

Sterculiaceae

Stipa viridula Trin

Stizolobium deeringianum Bort.

''Stone cells" (in Solanum

fruits).

Strophostyles leiosperma (T.

and G.) Piper.

Strophostyles pauciflora (see S.

leiosperma).

Suaeda depressa (Pursh.) S.

Wats.

Swainsona salsula (Pall.) Taub

Symphoricarpos occidentalis

Hook.

Tanacetum vulgäre L

Taraxacum erythrospermum

Andrz.

Taraxacum, officinale Weber

Teesdalia nudicaulis (L.) R. Br.

Tetragonía expansa Thunb

Teucrium botrys L

Teucrium canadense L

Thalictrum sp.

Thelesperma sp.

Thlaspi arvense L

Torilis anthriscus (L.) Bernh..

Page Page

57

70

126

'Î26"

70

70

126

126

70 126

84 107

66 126

73 142

84 113

84 107

Figure

41,42

26
TESTING AGRICULTURAL AND VEGETABLE SEEDS 393

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XXVI, 540

Page

Torilis nodosa (L.) Gaertn

Page Page Figure

XII, 216 Tradescantia virginiana L _

Tragopogón porrifolius L

Tragopogón pratensis L_

84 113

XXXIV, 733

XV, 271 Trianthema portulacastrum L

XXIII, 478 Trihulus terrestris L

XXIX, 610 Trichostema dichotomum L

XXIX, 611 Trichostema lanceolatum Benth_,

XII, 199 Tridens flavus (L.) Hitlichc_ _

250

252

254

254

252

253

254

252

252

252

252

Trifolium _ _ ,.

XXI, 425 Trifoliurn agrarium L _ __

XXII, 446

XXII, 445

Trifolium alexandrinum L

Trifolium ambiguum Bieb

77 142

XXI, 418 Trifolium angulatum Waldst.

and Kitt.

XXI, 426 Trifolium arvense L

XXII, 436 Trifolium bifidum A. Gray

Trifolium carolinianum Michx_

Trifolium cernuum Brot

Trifolium depauperatum Desv_

Trifolium dubium Sibth

Trifolium fimbriaium Lindl.

(see T. wildenovii).

Trifolium fragiferum L

Trifoliu7n glomeratum L

Trifolium gracilentum T. and G_

Trifolium hirtum All__ _ _

XXI, 422

XXI, 420

XXI, 424

XXI, 427 77 142

XXII, 437

XXI, 419

XXII, 438

253

252

254

254

253

254

77

77

142

142

XXII, 447

XXII, 439

XXII, 448

Trifolium hybridum L

Trifolium. incarnatum L

Trifolium involucratum Ortega.,

not Lam. (see T. wildenovii).

Trifolium lappaceum L

Trifolium medium L _ _

77

77

142

142

XXI, 429

XXII, 449

253

254

253

254

254

252

253

252

253

252

252

253

253

253

77 142

XXI, 434 Trifolium michelianum Savi

XXII, 440 Trifolium rnicrocephalum Pm'sh

XXII, 441 Trifolium microdon Hook, and

Arn.

XXI, 430 Trifolium nigrescens Viv

Trifolium ornithopodioides (L.)

Smith.

XXI, 423 Trifolium parviflorum'Ehrh __

XXI, 431 Trifolium pratense L 77

77

142

XXI, 428 142

XXI, 421

Trifolium procumbens L

Trifolium reflexum L

XXI, 432 Trifolium repens L 77

77

142

XXI, 435 142

XXI, 433

Trifolium resupinatum L

Trifolium striatum L_

Trifolium suaveolens (see T.

resupinatum).

Trifolium subterraneum L

Trifolium tridentatum Lindl _

XXII, 450

XXII, 442

254

253

253

253

77 142

XXII, 443 Trifolium variegatum Niitt _

XXII, 444 Trifolium wildenovii Spreng_ _

Trifolium wormskoldii Lehm.

(see T. wildenovii).

250 Trifolium spp

254

254

255

Trigonella

XXII, 451 Trigonella foenum-graecum L_

XXII, 452 Trigonella polycerata _ __ _

Triodia flava (see Tridens

flavus).

XII, 200 Trisetumflavescens (L.) Beauv-
394 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Botanical name Purity Germination

Plate

XII, 201

Page

Triticum aestivum L _

Page Page Figure

Triticum spp 62

80

126

XXV, XXVI, 521- 167

540

XIII. 226

Umbelliferae

Urtica dioica L .

XIII 226 Urticaceae__

Vaccaria pyramidata (see Saponaria vaccaria).

XXXI, 652-654 Valerianaceae 80 167

XXXI 653 Valerianella dentata Pollich _

XXXI 654 Valerianella eriocarpa Desv_

XXXI, 652 _ _- Valerianella locusta var. olitoria L.

Verhascum thapsus L__

80 167

XXX 628

XXVIII 582 Verbena hastata L__

XXVIII. 583 Verbena officinalis L

XXVIII 584 Verbena stricta Vent

XXVIII 585 Verbena urticaefolia L_ _

XXVIII 581-585 Verbenaceae

XXXIV 734 Vernonia noveboracensis

XXX 629 Veronica agr^stis L_

XXX 630 Veronica arvensis L

XXX. 631 Veronica peregrina L__

255

257

257

257

257

257

257

Vicia _ „

Vicia americana _ _ _ _

XXIII, 463-464___ Vicia angustifolia (L.) Reich. _

Vicia articúlala Hörnern

Vicia atropurpúrea D __ _ _

79

79

79

142

142

XXTI 459 142

XXIII 460 Vicia cracca L_

XXIII 466 Vicia dasycarpa Ten 79

79

142

Vicia faba TI _ - 142

XXIII 461 257

257

256

256

256

Vicia grandiflora Scop_

XXTI 453 Vicia hirsuta (L.) S. F. Gray

XXII 458 Vicia hybrida L _

XXTI 457 Vicia lútea L. __ _

XXII, 456 Vicia melanops Sibth. and Sn

Vicia monantha (see V. articúlala) .

Vicia pannonica Crantz

Vicia sativa L

XXII, 455

XXIII 462

256

257

257

257

79

79

142

142

XXII, 454

XXIII 465

Vicia tetrasperma (L.) Moench

Vicia villosa Roth__ 79

73

73

142

142

142

Vigna sesquipedalis W. F.

Wight.

Vigna sinensis (Torner) Hassk.

Viola tricolor L

XXIII, 467-468„_-

XXIV 505

257

XXIV 505 Violaceae

Weingaertneria canescens (see

Corynephorus canescens).

XXXIV 735 Xeranthemum cylindraceum ^

Zea mays L _ 62

62

62

126

126

126

39,40

Zea mays var. everta (Sturter.)

Bailey.

Zea mays var. saccharata Bailey.

231 Zoysia -_ - ---

231

231

231

XII, 202__ Zoysia japónica Steud

Zoysia matrella (L.) Merr

Zoysia tenuifolia Willd. ex

Trin.

Zveophvllaceae- __

65

65

126

XII, 203 126

XXIII 478
LIST OF PLANT NAMES

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION

Identification Common name Botanical name Purity Germination

Plate

IV, 79

Page

African millet...

Asia poppy, spotted (see

Roemeria poppy).

Alfalfa

Eleusine coracana

Page Page Figure

XX, 402 247 Medicago sativa. 77

82

142

167

53

XXIII, 469 Alñlaria. Erodium cicutarium.. _

231 Alkali sacaton __ SporObolus airoides ..

XVI, 314 Alyssum, hoary Bevtevoa incana

XVI, 310 Alyssum, pale Alyssum alyssoides

Amaranth, redroot (see

Rough pigweed).

Amaranth, spreading (see

Spreading pigweed).

Amaranth, tumble (see

Tumbling pigweed).

XXV, 522 Ammi, greater _ ._ Ammi ma jus

XVI, 294. •_.... Anemone, meadow-- Anemone canadensls

11,30 203 Angleton grass Andropogon nodosus

Artichoke Cynara scolymus

Asparagus ojficinalis

Geum sp

84

82

113

Asparagus 160

XVIII, 346 Avens

XXXII, 679-._. Bachelor's-button Centaurea cyanus -

VII, 145 223

235

Bahia grass _ Paspalum notatum _ _

Cardaría pubescens (Hymenophysa pubescens).

Neslia vaniculata

58 126

XVII, 323 Ballcress

XVII, 335 Ball mustard---

Balloon mustard (see Falseflax, big seed).

218 Barley

218

219

219

219

219

Hordeum

V,104 Barley Hordeum vulgäre 62 126

V,107 Barley, foxtail; wild barley;

squirreltail barley.

Barley, little

Hordeumjubatum... _

V, 105 Hordeum pusillum

V,106 Barley, meadow.- ._. Hordeum brachyantherum

(H.nodosum).

Hordeum leporinum (H.

murinum).

V, 108 Barley, mouse; wild barley.

Barnaby's thistle (see Starthistle, yellow).

IV, 77 214 Barnyard grass Echinochloa crusgalli

XVIII, 345 Base-rocket-- Reseda lutea

XXIX, 604 Basil

Basil-thyme (see Savory,

spring).

Bassia, fivehook

Satureja vulgaris

XIV, 250 Bassia hyssopifolia

XX, 410 248 Bean, Adzuki Phaseolus angularis

Vigna sesguipedalis

Phaseolus vulgaris

Phaseoluslunatus var. macrocarpus.

Phaseolus aureus

73

73

73

73

73

73

142

142

142

142

142

142

Bean, asparagus; yardlong .

Bean, field and garden

Bean, lima

44

45,46,

47

XX, 411 248 Bean, mung

Bean, runner .

Bean, wild

Phaseolus coccineus - _.

Strophostyles leiosperma (S.

pauciflora).

XXI, 416 249

395
396 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate Page

Bean, yardlong (see Bean,

asparagus).

Beardgrass, yellow

Page Page Figure

II, 28 Andropogon ischaemum -

203 Beardgrass, Queensland (see

Bluestem, silky).

Bedstraw (see Cleavers)

XXX. 648 Bedstraw, white Oalium mollugo

Beet, field (mangel) Beta vulgaris 84

84

84

74

107

107

107

142

Beet, garden Beta vulgaris 24,25

Beet, sugar _ Beta vulgaris var. saccharifera.

XIX, 375 241 Beggarweed, Florida Desmodium tortuosum....-

Belvedere (see Summer cypress).

196 Bentgrass

196

198

197

198

198

198

198

198

Agrostis

1,2 Bentgrass, colonial (browntop; Rhode Island bent).

Hort, vars.:

Astoria „

Agrostis tenuis 55 126

Highland (Dryland

bent).

Bentgrass, creeping (Seaside).

Bentgrass, Elliott

Agrostis palustris 55 126

I, 6 Argostis elliottiana

1,3-4 Bentgrass, spike Agrostis exarata

I, 5 Bentgrass, velvet Agrostis canina 55 126

1,7 Bentgrass, winter Agrostis hiemalis

111,62 Bermuda grass..- Cynodon dactylon (Capriola

dactylon).

Stachys annua

60 126

XXIX, 606 Betony, field

XXIX. 607 Betony, marsh Stachys palustris

258

258

258

Bindweed _ _ Convolvulus

XXVI, 549

XXVI ññO

Bindweed, field Convolvulus arvensis

Bindweed.'Hedge; great; wild;

bracted.

Bird-rape (see Turnip)

Convolvulus septum

XVIII, 350 Blackberry Rubus sp—

XXVIII 587 Black horehound Ballota nigra -

XIII 230 Black bindweed Polygonum convolvulus

XXXIII 723 Rudbeckia hirta

Bladder ketmia (see Flowerof-an-hour).

XXXI 662 Blowwives Achyrachaena mollis

Blue-bur (see Stickseed, European).

Blue cockle (see Corncockle) _

XXTX 610 Blnpmrl<i forked Trichostema dichofomum-.

XXTX 611 Binpcurls vinesrar Trichostema lanceolatum _ -

Blue devil (see Blueweed)...

XIII 224 Blue-eyed-grass

Bluegrass

Bluegrass, alkali

Bluegrass, annual

Sisyrinchium sp

224

226

226

226

227

225

Poa.

"Y" 171 » Poa iuncifolia

VITI,159,X,171Ä.

VIII, 160, X,171¿

VIII, 163

VIII, 164, X,171dX 171m

Poaannua _ 67 126

Poa ampia

Bluegrass, bulbous

Bluegrass, Canada

Tilnpcrrass Canbv

Poa bulbosa 67

67

126

Poa compressa 126

Poa canbyi

X Vl\n 226

227

226

225

226

226

Bluegrass, Cusick

Blueerass fowl

Poa cusickii

TX 168 X 171^ Poa palustrisIX. 165, X, 171p.

IX, 169, X, 171a.

Rlnpsrrass inland Poa interior

Bluegrass, Kentucky

Bluegrass, Merion

Bluegrass, Nevada

67 126

Poa pratensis

IX. 167, X, I7lk. Poa nevadensis 67 126
TESTING AGRICULTURAL AND VEGETABLE SEEDS 397

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

VIII, 162, X, 171^.

Page

227

225

227

226

Bluegrass, plains Poa arida _

Page Page Figure

IX, 170, X, 171&. Bluegrass; rough, roughstalk.

Bluegrass, Sandberg

Poatrivialis 67 126

X, 171i Poa secunda

VIII, 161, X, 171/. Bluegrass, Texas Poa arachnifera 67 126

X, 17U,- Bluegrass, Trinius Poa stenantha

IX, 166, X, 171c. 226 Bluegrass, wood __ Poa nemoralis 67 126

Blue sailors (see Chicory). _

202

203

203

Bluestem ._ Andropogon sp

11,29 .. Bluestem, Australian

Bluestem, big

Andropogon intermedius

11,25 Andropogon gerardi (A.

furcatus).

57 126

Bluestem, East Indies (see

Beardgrass, yellow).

11,27 203 Bluestem, little .

203

203

Andropogon scoparius

Andropogon hallii

57

57

126

126 11,26 Bluestem, sand

11,31 Bluestem, silky Andropogon sericeus...

Bluestem, Western (see

Wheatgrass, Western).

Blue thistle (see Blueweed)..

XXX, 649 Bluets, purple Houstonia purpurea

XXVII, 673.... Blueweed Echium vulgäre

XXXIII, 703... Blueweed; Texas blueweed.

Boisduvalia, dense-flowered.

Boisduvalia, stiff

Helianthus cîlîaris

XXV, 510 Boisduvalia densiflora.

XXV, 511 Boisduvalia stricta

Bristlegrass Setaria

X, 178 227

228

Bristlegrass, bur _ _ Setaria verticillata

X, 177 Bristlegrass, giant

Bristlegrass, green (see Foxtail, green).

Bristlegrass, Grisebach

Bristlegrass, knotroot

Bristlegrass, plains

Setaria magna

X, 174 228

228

228

Setaria grisebachii

X, 173... Setaria geniculata..

X, 176 Setaria macrostachya

Bristlegrass, yellow (see Foxtail, yellow).

Broadbean (see Horsebean)..

Broccoli... Brassica olerácea var. botrytis.

Brodiaea coronaria

83 119

XIII, 221 Brodiaea, harvest

XIII, 222.. Brodiaea, large-flowered

Brome, California

Brodiaea grandiflora

210 Bromus carinatus

Brome, downy (see Chess,

downy).

209 Bromegrass BroTnus

Brome, Japanese (see Chess,

Japanese).

111,57 210 Brome, mountain

210

230

Bromus marginatus 59

59

70

126

126

126

111,55 Brome, smooth

XI, 194 Broomcorn Sorghum vulgäre var. technicum.

Broomcornmillet (see Proso) _

11,32 203 Broomsedge

221

Andropogon virginicus

VI, 136.... Browntop millet (see Panicum, browntop).

Browntop (see Bent

grass, colonial).

Brussels sorouts

Panicum ramosum ' 65 126

Brassica olerácea var. gemmifera.

83 119

Buckhorn (see Plantain, 1 buckhorn)

' The name browntop millet has been applied to browntop panicum (P. fasciculatum); P. ramosum is

the species in cultivation.

957116—52 27
398 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XXIX, 620-..

11,45

XXVIII, 586-.

XXVIII, 593..

XII, 214..-.

XX, 401..--

XX, 399....

XX, 398....

XXXI, 670.

XVIII, 352..

XVIII, 351_.

XXXII, 694.

XXXII, 695.

XXXII, 698.

XXXII, 699.

XXIX, 625-.

XVI, 300..

XVI, 302..

XVI, 301-.

XVI, 299..

XVI, 303.

XXVI, 547-

XX, 401...

XXX, 645.

XXX, 646.

XVI, 305-.

XVIII, 355.

XV, 289..

XV, 280-

VII, 155..

VII. 156-

VII, 153..

Page

208

246

246

246

246

238

232

232

223

223

224

224

224

Buckwheat, common

Buflalo-bur

Buffalo grass

Bugle, groundBugleweed, American

Bug-seed (see Tickseed)

Bullnettle (see Horsenettle)

Bulrush

Bur-clover, button

Bur-clover, California

Bur-clover, spotted

Burdock, great

Burnet, little

Burnet, prairie

Bur-ragweed (see Bur-sage,

skeletonleaf).

Burnweed

Burnweed, Australian

Bur-sage, skeletonleaf

Bur-sage, slimleaf..

Butter-and-eggs.__.

Buttercup, bulbous

Buttercup, common (s

Buttercup, tall).

Buttercup, creeping

Buttercup: sticktight; smallnowered.

Buttercup, tall

Buttercup: wartseed; hairy

Butterfly-weed

Butterprint (see Velvetleaf).

Buttonclover

Buttonweed, rough ...

Buttonweed, Virginia

Caley pea (see Rough pea) -.

California-poppy

Caltrop (see Puncture vine).

Caltrops (see Star-thistle,

purple).

Camelthorn

Camomile, field (see Cornchamomile).

Camomile, golden (see

Chamomile, yellow).

Campion

Campion, bladder

Campion, red

Campion: White; evening

(see Cockle, white).

Canary grass

Canary grass

Canary grass, Carolina

Canary grass, hood

Canary grass, little .—

Fagopyrum esculentum.

Solanum rostratum

Buchloe dactyloides

Ajuga chamaepitys

Lycopus virginkus

Page

81

Page

167

Figure

Scirpus sp

Medicago orbicularis,

Medicago hispida

Medicago arabica

Arctium lappa

Sanguisorba minor..-

Sanguisorba annua..

Erechtites hieracifolia

Erechtites prenanthoides...

Franseria discolor (Gaertneria discolor).

Franseria tenuifolia

Linaria vulgaris {L. linaria) -

Ranunculus bulbosus

Ranunculus repens

Ranunculus parviflorus.

Ranunculus acris

Ranunculus sardous

parvulus).

Asclepias tuberosa

(i?.

Medicago orbicularis

Diodia teres

Diodia virginiana

Brassica olerácea var. capitata.

Eschscholtzia calif ornica..

Alhagi pseudalhagi {A.

camelorum).

Lychnis

Silène cucubalus (S. latifolia).

Lychnis dioica

Phalaris

Phalaris canariensis.

Phalaris caroliniana.

Phalaris paradoxa—

Phalaris minor

142

142

83

60
TESTING AGRICULTURAL AND VEGETABLE SEEDS 399

INDEJC FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

VII, 152

Page

223

224

Canary grass, reed Phalaris arundinacea

Phalaris augusta-..

Page

60

Page

126

Figure

VII, 151 Canary grass, timothy.

Cantaloup (muskmelon)

Caraway _

Cucumis melo 82 124

XXV, 531 Carum carvi

Cardoon Cynara cardunculus 84 113

Carolina geranium (see

Cranesbill, Carolina).

Carolina horsenettle (see

Horsenettle).

208 Carpet grass

208

208

Axonopus .__

11,43 Carpet grass, broad-leaved._.

Carpet grass, narrow-leaved.

Carrot (cult.)

Axonopus compressus

11,42 AxonoDus aflinia 58

80

126

XXVI, 167 535 Daucus cavota 61

XXVI, 535 Carrot, wild Daucus carota

XV, 285 233

233

233

233

233

233

Catchfly, conical Suene cónica

XV, 287 Catchfly, Cretian Suene crética

XV, 284 Catchfly, English Silène gallica (S. anglica)

XV, 290 Catchfly: Forked; clover

Catchfly, night-flowering

Catchfly, sleepy

Silène dichotoma

XV, 291 Silène noctiflora

XV, 283 Silène antîrrhina

Catchweed (see Cleavers)

XXVIII, 697-— Catnip Nepeta cataria

XXXIII, 707... Cats-ear, spotted Hypochaeris radicata

Cattail millet (see Pearl millet).

Cauliflower _ . Brassica olerácea var. botrytis. *

Apium graveolens var. rapaceum.

Apium graveolens var. dulce.

Apium ammi

83

80

80

119

167

167

Celeriac

Celery

XXV, 525 Celery, wild

IV, 91 Centipede grass Eremochloa ophiuroides

XXXI, 655 Cephalaria Cephalaria transylvanica

XXXI, 668 Chamomile, yellow Anthémis tinctoria

Chard, Swiss Beta vulgaris var. cicla

Brassica kaber (B. arvensis).

84 107

XVII, 317 235 Charlock

Cheat (see Chess)

XXIV, 499 Cheesemallow, plains

Cheesemallow, Henderson...

Cheeses (see Mallow, running).

Chervil

Sidalcea campestris

XXIV, 500 Sidalcea hendersonii

XXVI, 532 Chaerophyllum sp

111,53 211

211

210

210

211

211

Chess

Chess, barren

Bromus secalinus _

111,50 Bromus sterilis.

111,49 Chess, downy . Bromus tectorum

Chess, foxtail Bromus rubens

111,52 Chess, hairy Bromus commutatus

111,51 Chess, Japanese Bromus japonicus-.

Chess, poverty (see Chess,

barren).

III, 54.._. _ 211 Chess, soft

239

Bromus mollis (B. hordeaceus).

XIX, 366 Chickpea Cicer arietinum 73 142

XV, 277- Chickweed, big mouse-ear...

Chickweed, common

Chicory

Cerastium vulgatum

XV, 275 Stellaria media (Alsine

media).

XXXII, 690.... 84 113

111,58 212 Chloris, slender

Chufa (see Nutgrass, yellow). .

Cinquefoil, Montpelier (see .

Chloris divaricata

XVIII. 347..

Strawberryweed).

Cinquefoil, oldfleld Potentilla canadensis
400 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XXX, 647-.

XXII, 439-.

XVIII, 356..

XXI, 430...

XXII, 446..

XXI, 434.._

XXI, 421...

XX, 399.._.

XXI, 422.-

XXI, 419..

XXII, 448.

XXI, 418-.

XXI, 420..

XXII, 445.

XXI, 429._

XXI, 428..

XXI, 435.-

XXII, 436..

XXII, 438.

XXI, 424. _

XXI, 426. -

XXI, 431..

XXII, 447.

XXII, 444.

XXII, 440-

XX, 406....

XXII, 437..

XXI, 433--.

XXIT, 450..

XXI, 427...

XXI, 423..

XXII, 441..

XXII. 442-,

XX, 404...

XXI, 432..

XXII, 443.

XXI, 425-.

XX,405„ -

XXII, 449.

111,61

Page

2.50

253

238

252

254

253

252

246

252

252

254

252

252

254

253

252

253

254

254

252

253

253

254

253

254

253

253

254

252

252

254

253

247

253

253

252

247

254

212

XV, 279 232

Citron

Cleavers -

Clover

Clover, alsike

Clover, alyce

Clover, ball

Clover, Lerseem

Clover, big-flowered—

Clover, buffalo

Clover, bur

Clover, burdock (see Clover,

lappa).

Clover, Carolina

Clover, cluster

Clover, crimson

Clover, crooked

Clover, drooping-ñowered--.

Clover, dwarf sack (see

Clover, poverty).

Clover, knotted (see Clover,

striate).

Clover, kura

Clover, ladino (see Clover,

white).

Clover, lappa

Clover: Large hop; low hop.

Clover, Persian

Clover, pinole

Clover, pinpoint

Clover, poverty

Clover, rabbitfoot

Clover, red -- -

Clover, rose

Clover, seaside

Clover, smallheaded

Clover, small hop (see Clover,

suckling).

Clover, sour

Clover, strawberry

Clover, striate

Clover, sub

Clover, sucklingClover, teasel

Clover, thimble

Clover, tomcat

Clover, white sweet

Clover, white..-

Clover, whitetip

Clover: Yellow hop; yellow.

Clover, yellow sweet

Clover, zigzag

Club-awn

Coast dandelion (see Catsear, spotted).

Coast blite (see Goosefoot,

red).

Cockle (see Corncockle)

Cockle, pink (see Cowcockle).

Cockle, sticky (see Catchfly,

night-flowering).

Cockle, white...

Citrullus vulgaris

Galium aparine

Trifolium spp

TnfoUum hybridum

Alysicarpus vaginalis

Trifolium nigrescens

TnfoUum alexandrinum.

Trifolium michelianum-.

TnfoUum reflexum

Medicago hispida

Page

82

Trifolium carolinianum..

Trifolium glomeratum...

Trifolium incarnatum—

Trifolium angulatum—

Trifolium cernuum

Trifolium ambiguum..

Trifolium

Trifolium

Trifolium

Trifolium

Trifolium

Trifolium

Trifolium

Trifolium

TrifoUum

Trifolium

Trifolium

lappaceum

procumbens

resupinatum..-

bifidum ---

gracilentum

depauperatum.-

arvense

pratense

hirtum

wildenovii

microcephalum.

Melilotus indica

Trifolium fragiferum

Trifolium striatum

TrifoUum subterraneum..

Trifolium dubium _ -

TrifoUum parviflorum...

Trifolium microdon

Trifolium tridentatum—

Melilotus alba

Trifolium repens

Trifolium variegatum

TrifoUum agrarium

Melilotus officinalis

Trifolium medium

Corynephorus canescens-.

Page

124

77

Lychnis alba...

142

142

142

142

Figure

142

142

142

142

142

142

142

75 142

77 142

142
TESTING AGRICULTURAL AND VEGETABLE SEEDS 401

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate Page

Cocksfoot grass (see Orchard

grass).

Coco grass (see Nutgrass). _

Page Page Figure

Coffee bean (see Sesbania). _.

XX, 403 247 Cogwheel clover Medicago tuberculata

CoUards _ Brasska olerácea var. acephala.

Brauneria anqusíifoiia

83 119

XXXI, 672 Cone-flower, purple

Combind (see Black bindweed).

XV, 273 Corncockle Agrostemma githago

XXXI, 666 Corn-chamomile Antfiemîs arvensis

Com, field Zea Tnavs 62 126 39,40

Cornfiower (see Bachelor'sbutton).

Corn, pop . Zea mays var. everta

Valerianella locusta var.

olitoria.

Valerianella eríocarpa

62

80

126

167 XXXI, 652 Comsalad—_

XXXI, 654 Cornsalad, Italian

XXXI, 653 Comsalad, toothed Valerianella dentata

Corn, sweet Zea mays var. saccharata..

Coronilla scorpioides

62 126

XIX, 367 240 Coronilla, scorpion

Cotton 81 164

Couch grass (see Quackgrass).

Cowcockle .

59

XV, 281 Saponaria vaccaria

Cowherb (see Cowcockle)..

XXIII, 467-468. 257 Cowpea Vigna sinensis 73

73

142

Cowpea, 142 yardlong Vigna sesquipedalis. _

XXIX, Melampyrum arríense 626 Cow wheat

IV, 75 Crabgrass; large crabgrass._.

Crabgrass, slender.

Crabgrass, smooth

Digitaria sanguinalis (Syntherisma sanguinalis).

Digitaria filiformis IV, 73

IV, 74 Digitaria ischaemum (Syntherisma ischaemum).

XXIII, 470 Cranesbill, Carolina Geranium caroliniaTtiim

XXIII, 472 Cranesbill, cutleaf Geranium dissecfum

XXIII. 473 Cranesbill, dovefoot. Geranium molle

XXIII, 471 Cranesbill, longstalk _

Cranesbill, small

Geranium columbinum

XXIII, 474 Geranium pusillum

Creeping Jennie (see Bindweed, field).

Cress, garden . _ 83 119 XVII, 322 235 Cress, hoary Cardaria draba

Cress, water Rortppa nasturtium-aquaticum.

Crotalaria spp

83 119

240

240

240

240

240

240

Crotalaria

XIX, 370 Crotalaria, lance Crotalaria lanceolata

Crotalaria spectabilis

Crotalaria intermedia

Crotalaria mucronata (C.

striata).

74

74

74

74

74

142

142

142

142

142

XIX, 372 Crotalaria, showy 56 XIX, 369

XIX, 371

Crotalaria, slenderleaf

Crotalaria, striate

Crotalaria, Sunn,.

XXIII, 480 Crotón Crotón sp

XIX, 368 239

240

Crownvetch Coronilla varia. __

XIX, 367 _ Crownvetch, scorpion

Cucumber

Coronilla scorpioides

82 124 IV, 92 Cupgrass, Louisiana

Curlybloom

Eriochloa punctata

34

XXVII, 568 Phacelia sp

XXXII, 689-... Daisy: Oxeye: field: white.. ChrvsantheTnum le.ii.rn.in..

VII,140____ 222

themum.

Dallis grass Paspalum dilatatum 68 126
402 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification

Plate

XXXIV, 730-

XXXIV, 731.

V,113---

XII, 215.

m

XX, 392-

XX, 390-

XV, 278-

XIII, 240.

XIII, 238.

XIII, 239-

XIII, 243-

XIII, 242.

XIII, 237.

XIV, 245.

XIII, 241.

XIV, 244.

Page

XXVII, 557-_

XXVII, 560.-

XXVII, 558. -

XXVII, 562- -

XXVII, 556- -

XXVI, 543..

XXVI, 542.

XXXI, 667.

111,65

111,64

XXVIII, 596..

XII, 198-..

XII, 197...

XII, 196...

XXV, 527-

XVII, 329.

XXV, 518-

220

245

245

Common name

XXVII, 559---

XXVII, 561 260

260

260

260

260

212

213

213

231

231

231

214

Dandelion

Dandelion, red-seeded..

Darnel; bearded darnel

Dayflower, common

Dead nettle (see Henbit)—

Deathweed (see Sumpweed,

poverty).

Deervetch, American (see

Prairie-trefoil).

Deervetch, hispid

Deervetch, slenderpod

Deptford pink.-

Desert pm-slane (see Horsepurslane) .

Devil's paintbrush (see

Hawkweed, orange).

Dock: Broad-leaved; bitterDock: Clustered; green

Dock: Curly; sour; yellow..

Dock, fiddleleaf

Dock, golden

Dock: Peach-leaved; smooth

Dock, sour (see Sorrel, garden).

Dock, veiny

Dock, western.-

Dock, willow-leaved

Dodder

Dodder: Bigseed; largeseeded alfalfa.

Dodder, Chilean

Dodder, clover. .--

Dodder: Field; large seeded.

Dodder, flax

Dodder, Gronovius

Dodder: Littleseed; smallseeded alfalfa.

Dogbane, hemp

Dogbane, spreading

Dogfennel--.

Dogtail

Dogtail, bristly

Dogtail, crested

Dragonhead, American..

Dropseed, puff

Dropseed, sand

Dropseed, scratch.

Earth nut

Echinochloa..

Eggplant

Endive

Erysimum, smallflower_

Botanical name

Taraxacum officinale

Taraxacum erythrospermum.

LoUum temulentum

Commelina communis

Purity

Lotus hispidus

Lotus angustissimusDianthus armería

Rumex obtusifoUus

Rumex conglomeratusRumex crispus

Rumex pulcher

Rumex persicarioides—

Rumex altissimus

Rumex venosus

Rumex occidentalis..

Rumex salicifoUus-.

Cuscuta

Cuscuta indecora.-

Cuscuta racemosa var.

chiliana

Cuscuta epithymum

Cuscuta pentágona (C.

arvensis).

Cuscuta epilinum

Cuscuta gronovii

Cuscuta plañí flora

Page

84

Germination

113

Figure

Evening-primrose -

Apocynum cannabinum. _.

Apocynum androsaemifolium.

Anthémis cotula

Cynosurus

Cynosurus echinatus

Cynosurus cristatus

Moldávica parviflora (Dracocephalum parviflorum).

Sporobolus neglectus

Sporobolus cryptandrus

Sporobolus clandestinus —

Bunium bulbocastrum

{Carum bulbocastrum).

Echinochloa

Sólanum melongena var.

esculentum.

Cichorium endivia. —

Erysimum inconspicuum

(E. parviflorum).

Oenothera biennis.

126

167

113
TESTING AGRICULTURAL AND VEGETABLE SEEDS 403

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XXV 519

Page

Evening-primrose, cutleaf...

Evebrieht

Oenothera laciniata {Raimannia laciniata).

Euphrasia sp

Page Page Figure

XXTX fi23

XXXIII 715 Fall-dandelion Leontodón autumnalis

V 109 219 Fall witchgrass Leptoloma cognatum

XXXIII. 719 False-camomile Matricaria inodora

XVII, 321 Falseflax, bigseed Camelina sativa _

XVII 320 Falseflax: Little-seed; smallseeded.

False-mallow, red (see Globemallow, scarlet).

False-mallow, yellow ..-

Fanweed (see Pennycress) —

Camelina microcarpa

XXIV 501 Sidopsis hispida __

XIV 246 Fat-hen Atriplex patula var. hastata.

Fennel-flower (see Love-ina-mist) .

Fennel-flower, garden

Fenugreek

Fescue .-

Fescue, Chewings

XVI, 298 NigeUa sativa (N. arvensis)

Trigonellafoenum-graecumFestuca

XXII, 451 254

216

217

217

218

217

217

217

218

Festuca rubra var. commutata.

Festuca capillata _

61

61

61

126

126

126

Fescue, hair

IV 93 Fescue, meadow Festuca elatior

IV, 96 Fescue, rattail Festuca myuros

IV, 95 - Fescue, red Festuca rubra 61

61

61

126

126

126

Fescue, sheep

Fescue, tall

Hort, vars.: Alta.

Festuca ovina _

IV, 94 Festuca arundinacea

Ky-31

XI, 193 230 Feterita Sorghum vulgäre var

Fetticus (see Cornsalad)

XXVII, 571 Fiddleneck-.- Amsinckia tesselata

XXVII, 570 Fiddleneck: Coast; fireweed.

Field camomile (see Camomüe, field).

Fieldcress, yellow

Amsinckia intermedia

XVII, 339 .._ 237 Rorippa austriaca .

XXX, 649 Field houstonia Houstonia purpurea

XXX, 650 -- Field madder Sherardía arvensis

XXIX, 627 Figwort, American. Scrophularia marilandica—-

211

212

212

Fingergrass Chloris

111,58 -.-.- Fingergrass, Australian

Fingergrass, feather

Chloris divaricata

Chloris virgata _.

Fireweed (see Burnweed)___

Fivefinger (see Cinquefoil,

oldfield).

XXX, 628 Flannel mullein. _ Verbascum thapsus. - _ .

XIX, 383 243 Flat pea.. Lathyrus sylvestris

XIV, 265 Flatweed.-—_ Roubieva multifida

XXIII, 476 Flax Linum usitatissimum

Linum tñrginianum

81 162 58

XXIII, 477 Flax, woodland.

Fleabane, Canada (see Horseweed) .

Fleabane: Daisy; whitetop..-

Florida beggarweed ..

XXXIl, 696 Erigeron annuus

XIX, 375 241 Desmodium tortuosum 74 142

Florida velvetbean (see Velvetbean) .

XXIV, 491 Flower-of-an-hour_ ___ Hibiscus trionum

XXV, 521 Fool's parsley Aethusa cynapium

XXVII, 579 Forget-me-not Myosotis arvensis

XV, 27U—. Four-o'clock, wild Mirabilis nyctaginea
404 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate Page

202

227

202

227

228

1,20

X, 172 .

X,179 -

T, 19 202

202

202

229

1,23

1,21 -

X, 175

XVI, 309 -

XXXITI, 700...

XIII, 220 .

XXV, 515 ._.

XXV, 512 —

XXV, 513

XXV, 514 —.

XXIX, 609 .

XXIX, 608-.

X, 172 227

XXVII, 563- _

XXVII, 564

XXVII, 565-_

XXIV, 502

XIX, 376 241

XXV, 516 —

XXXI, 669

XIV, 255..

XIV, 254

XIV, 256

XIV, 257

XIV, 252

XIV, 258

IV, 80—.

11,47 _ 209

209

209

209

11,48

11,46 _.

XIII, 223

XXXIV, 732

XXVII, 578

XXIX, 615

XXIX, 614 .

XXIX, 616

XIX, 385

XXXIV. 725-.--

243

Foxtail

Foxtail

Foxtail, Carolina

Foxtail, giant

Foxtail, green

Foxtail, meadow (see Meadow foxtail).

Foxtail, short-awn

Foxtail, slender

Foxtail, water

Foxtail, yellow

French weed (see Pennycress) (see also Galinsoga).

Fumitory, common

Gaertneria (see Bur-sage,

skeletonleaf).

Galega (see Ooatsrue)

Galinsoga

Garlic, wild.--

Gaura, hairy

Gaura, scarlet

Gaura, scented

Gaura, wavy-leaved

Germander, American

Germander, cut-leaf

Giant foxtail

Gilia

Gilia, higflower

Gilia, globe

Globemallow, scarlet

Goats-beard (see Salsify,

meadow).

Goatsrue, common

Goatweed (see St. Johnswort).

Godetia

Goldenweed, hairy

Goosefoot (see Lambsquarters)

Goosefoot, bigseed

Goosefoot, mapleleaf

Goosefoot, narrowleaf

Goosefoot, nettleleaf

Goosefoot, pltseed

Goosefoot, red -._

Goosegrass.-

Grama, blue

Grama grass

Grama, hairy

Grama, side-oats

Grape-hyacinth, tassel

Greenthread

Gromwell: Field; corn

Groundcherry, perennial. __

Groundcherry, purple-flowered.

Groundcherry, taperleaf—

Groundnut pea

Groundsel, common

Alopecurus

Setaria.-.

Alopecurus caroUnianus..

Setaria faberi

Setaria midis

Page Page Figure

Alopecurus aegualis

Alopecurus myosuroides..

Alopecurus geniculatus. -

Setaria luiescens

Fumaria officinalis..

Galinsoga parviflora..

Allium viveale

Gaura villosa

Gaura coccínea

Gaura odorata

Gaura sinuata

Teucrium canadense..

Teucrium botrys

Setaria faberi

Collomia gracilis

CoUomia grandiflora.

Gilia capitata

Sphaeralcea coccínea.

Galega officinalis..

Godetia tenella.. _

Aplopappus ciliatus {Piionopsis ciliata).

Chenopodium hybridum

var. gigantospermum.

Chenopodium hybridum

Chenopodium leptophyllum.

Chen opodium murale

Chenopodium berlandieri...

Chenopodium rubrum

Eleusine indica

Bouteloua gracilis

Bouteloua

Bouteloua hirsuta

Bouteloua curtipendula

Muscari comosum

Thelesperma sp

Lithospermum arvense

Physalts longifolia

Physalis lobata {Quincula

lobato).

Physalis subglabrata

Lathyrus tuberosus

Senecio vulgaris
TESTING AGRICULTURAL AND VEGETABLE SEEDS 405

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification Common name Botanical name Purity Germination

Plate Page

Groundsel, ragwort (see Ragwort, tansy).

Quar

Page Page Figure

XIX, 373 240

221

201

213

201

201

213

Cyamopsis tetragonolobus

VI, 132 Guinea grass Panicum maximum

Grindelia sguarrosa.

65 126

XXXIII, 701... Gumweed, curlycup

Hairgrass.. Aira

111,70 Hairgrass, crinkled Deschampsia flexuosa

1,17 Hairgrass, fine Aira elegans (Aira capillaris)

1,18 Hairgrass, silver Aira caryophyllea

111,69.... Hairgrass, tufted

Halogeton

Deschampsia caespitosa

XIV, 263 Halogeton glomeratus

VII, 154 224

236

Harding grass Phalaris tuberosa var. stenoptera.

Conringia orientalis

60 126

XVII, 325 Hares-ear-mustard

XXXIII, 716-. _ Hawkbit, rough Leontodón nudicaulis

XXXII, 693b._. Hawksbeard, hairy Crépis setosa

XXXII, 693a_.. Hawksbeard, smooth

Hawkweed, orange

Crépis capillaris

XXXIII, 706-_. Hieracium aurantiacum

XXXIII, 721... Hawkweed, picris Picris hieracioides..

XXVIII, 598-._- Heal-all Prunella vulgaris

XXVI, 550 258 Hedge-bindweed Convolvulus septum.-

XVIII, 342 Hedgemustard Sisymbrium officinale (Erysimum officinale).

Hedgenettle (see Betony,

field).

XXVI, 539 Hedgeparsley, erect Torilîs anthriscus ... .

XXVI, 540 _ Hedgeparsley, knotted

Hegari ._--

Torilis nodosa .

XI, 192 230 Sorghum vulgäre var

XXVII, 575-.__. Heliotrope, common

Heliotrope, salt

Hemizonia

Heliotropium europaeum

XXVII, 574 Heliotropium curassavicum.

XXXIII, 704... Hemizonia luzulaefolia

84 167 XIII, 225 Hemp

XXVIII, 589.... Hempnettle, bristlestem

Hempnettle, red

Qaleopsistetrahit. _ --

XXVIII, 588-_. Galeopsis ladanum

XXIX, 613 Henbane, black Hyoscyamus niger

XXVIII, 591_... Henbit Lamium amplexicaule

Herd's-grass (see Redtop)

XXVIII, 594--- Horohound, white _ Marrubium vulgäre

XVII, 322 235 Hoary cress Cardaria draba (Lepidium

draba).

XII, Rhynchospora macrostachya 213 Horned-rush

Hornpoppy, blackspot (see

Sea-poppy).

Horsebean . Vicia faba 79 142

XXIX, 617 Horsenettle; Carolina horsenettle.

Horsenettle, white (see

Nightshade, silverleaf).

Horse-purslane

Solanum caroUnense

XV, 271 Trianthema portulacastrum.

XXXII, 697--.. Horseweed Erigeron canadensis.

Husk tomato Physalis pubescens 80 167

XI, 187 Hybrids; Sorghum—Sudan

XXV, 509 Hyssop loosestrife Lythrum hyssopifolia

XXXIV, 735.-- Immortelle, cylinder

Indian grass, yellow

Xeranthemum cylindra- .

ceum.

Sorghastrum nutans 57 ]26 .

Indian hemp (see Dogbane, .

hemp).

XXXI, 660 Indian-tobacco Lobelia inflata

Indigo, curly (see Joint- .

vetch. Northern).
406 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XIX, 380

XXXIV, 734__-

XII, 202

IV 78

Page

242

231

214

Jndigofera hirsuta

Page Page Figure

Ironweed, New York

Zoysia japónica 65

65

126

Japanese millet. Echinochloa crusgalli var. 126

frumentacea.

Jim Hill mustard (see Tumblemustard).

Y"V"T"V ß19 Datura stramonium.—

XI 185 230

238

214

230

Johnson grass Sorghum halepense - - 70 126

XVIII, 354 Jointvetch, Northern

Echinochloa colonum -_

"VT 101 Kafir Sorghum vulgäre yar..

Kale Brassica olerácea var. acephala.

Brassica napus var. pabularia

Anthyllis vulneraria

83 119

234

XVIII, 357 238 Tí'iflTiPwetí'h

King devil weed (see St.

Johnswort).

Klamath-weed (see St.

Johnswort).

Knapweed, brownscale Centaurea jacea

"VWTT fiQl Centaurea pieris (C. repens)

Centaurea maculosa -

Scleranthus annuus

TCnnftrrass fsee WireKrass)—-

Knotweed

K n 01 w e e d, Pennsylvania

(see Ladysthumb, bigseed).

Knotweed, prostrate (see

Knotweed).

Knotweed, silversheath

Kohlrabi-.-

Kudzu -

Kyllinga --

Lacegrass

Ladysthumb

Ladysthumb, bigsecd

Ladysthumb, pale

Lambsquarters; goosefoot.—

Polygonum aviculare.

Ç-TTT 997 Polygonum argyroeoleon-...

Brassica olerácea var. gongylodes.

Pueraria thunbergiana

Kvllinaa sv

83

74

119

142 XXI, 413 249

216 VranroRtÎR CíiVíllüTíS

Polygonum persicaria

Polygonum pensylvanicum.

XIII, 232

Chfinnnndifim album XIV, 251 ---

Arnoseris minima

Larkspur, field

Larkspur, Menzies field—

Lavender grass (see Moorgrass).

Leek -

XVI, 295

JlfiJnhhi 'illm fïieïi zîesH XVI, 296

Atlium porrum ..-.

Lespedeza bicolor-- —

82 160

244

244

244

244

244

244

244

Lespedeza, bicolor -.

XIX, 386 Lespedeza, common (striatc). -.

XIX, 387

XX, 388

XX, 389

Lespedeza striata

Lespedezastriatavar Kobe.

Lespedeza stipulacea

. Lespedeza cunéala (L.

sericea)

Lespedeza bicolor

74

74

74

74

142

142

142

142

Lesnedeza. Korean..

Lespedeza: Sericea; Chiuose.

Lespedeza, Siberian . Lespedeza hedysaroides

Lactuca sativa

74

84

142

113 Lettuce .-

27,

XXXIII, 713 Lettuce: Blue; chicory . Lactuca pulchélla

. Lactuca scariola var. integrifolia (L. intégrala).

. Lactuca canadensis

28,29

XXXIII, 711.. Lettuce, tall.
TESTING AGRICULTURAL AND VEGETABLE SEEDS 407

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification Common name Botanical name Purity Germination

Plate

XXI, 416

V, 101

Page

249

XVI, 297 -

215

216

216

216

216

IV, 87

IV, 89

IV, 90 -

IV, 88 -

XX, 396 246

246

XX, 397 246

XXVII, 572

XXIV, 497

XXIV, 495

XXIV, 493

XXIV, 492

XXIV, 498

XXIV, 494

XII, 203

V, 98

231

V, 99

V, 100 _-

XIII, 225

231

1,22 202

XVI,304-__

246

247

247

XX, 400

XX, 403

XXV, 508 . -

XXIV, 507

XXIV, 506 —

XVIII, 359

XVIII, 358

XVIII, 361

XVIII. 362

XVIII, 363

XVIII, 360

XXVI, 548

239

239

239

239

239

239

XXVI, 546_—..

XXVI, 544.___

XXVI, 545 _

227

229

229

229

229

229

XI, 180 .-

XI, 182 . _

XI, 181

XI, 183

Little flower mealybean..

Lizard-tail grass..,

Love-in-a-mist

Lovograss

Lovegrass, Boer.

Lovegrass, Lehmann

Lovegrass, sand

Lovegrass, weeping

Lovevine (see Dodder, field).

Lupine, blue

Lupine, white

Lupine, yellow

Madwort, German

Mallow: Alkali; white; creeping.

Mallow, high

Mallow, little

Mallow, musk

Mallow, prickly. -

Mallow, running

Mangel (see Beet, field)

Manila grass

Mannagrass

Mannagrass, American

Mannagrass, fowl

Marijuana

Marsh elder (see Sumpweed,

poverty).

Mascarene grass

Mayweed (see Dogfennel)...

Mayweed, scentless (see

False-camomile).

Meadow foxtail

Meadow-rue

Meadow softgrass (see Velvetgrass).

Medic

Medic, black.

Medic, cogwheel

Mentzelia, bractless

Mentzelia, bushy

Mentzelia, whitestem

Merker grass (see Napier

Mignonette, yellow (see Baserocket) .

Milkvetch, chickpea

Milkvetch, Chinese

Milkvetch, üexuous_.

Milkvetch, nuttall

Milkvetch, ruby

Milkvetch, sicklepod

Milkweed, climbing

Milkweed, common

Milkweed, Mexican

Milkweed: whorled; poison..

Millet

Millet, foxtail

Hort, vars.: Common

German

Hungarijin

White Wonder.

Strophostyles leiosperma

(S. pauciflora).

Hackelochloa grannlaris

Nigella damescena

Eragrostis

Eragrostis chloromelas

Eragrostis lehmanniana

Eragrostis trichodes

Eragrostis curvula

Page Page

Lupinus angustifolius-.

Lupinus albus

Lupinus luteus

Asperugo procumbens-.

Sida hederacea

Afalva sylvestris

Malva parviflora

Malva moschata

Sida spinosa

Malva rotundifolia..

Zoysia matrella..

Glyceria fluitans.

Glyceria grandis..

Glyceria striata...

Cannabis sativa..

Zoysia tenvijolia.

Alopecurus pratensis..

Thálictrum sp

Medicago

Medicago lupulina

Medicago tuberculata..

Mentzelia nuda

Mentzelia dispersa

Mentzelia albicaulis...

Astragalus cicer

Astragalus chinensis

Astragalus flea uosus

Astragalus niittallianus..

Astragahis rubyi

Astragalus falcafus.

Gonolobus laevia

Asclepias syriaca

Asdepias mexicana

Asclepias galioides

Setaria

Setaria itálica

Setaria itálica

Setaria itálica

Setaria itálica

Setaria itálica

142

142

142

126

Figure
408 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification

Plate

XI, 190

XXVIII, 595..

V, 114

V, 115

XXVI, 553-

XXVI, 555-

XXVI, 552..

XXVIII, 592..

XXVIII, 599..

XXX, 628...

XVII, 319-.

XVII, 324..

XVII, 316-

XVII, 330-

XVII, 333-

X, 171r.

X, 171?-

VII, 150

XXVII, 506.

XT, 195..--

XIII, 226...

XXIX, 619.

XXIX, 621.

XXIX, 618_

Page

230

XXXIII, 714.

V, 97

XII, 207

XII, 206

11,36..

11,38-,

11,37-,

11,41.

II, 40-

11, 39.

259

259

259

259

235

236

235

237

235

226

226

223

Common name

Milo

Mint, field

Molasses grass...'.

Moorgrass

Morning-glory

Morning-glory, bigroot (see

Wild potato vine).

Morning-glory, common

Morning-glory, European

(see Bindweed, field).

Morning-glory, hairy..

Morning-glory, ivy-leaf

Morning-glory, small-flowered white.

Motherwort

Mountain-mint

Mouse-ear (see Chickweed,

big mouse-ear).

Mullein: Common; flannel.

Muskmelon

Mustard

Mustard: Black; Trieste...

Mustard, blue

Mustard: Brown; India.—

Mustard, hairy

Botanical name

Sorghum vulgäre var..

Mentha arvensts

Melinis minutiflora..

Molinia caerulea

Ipomoea

Purity Germination

205

207

207

207

208

207

207

Mustard, pereimial

Mustard, spinach

Mustard, Trieste (see Mustard, black).

Mustard: White; yellow;

white London.

Mustard, wild (see Charlock).

Muttongrass

Muttongrass, longtongue...

Napa thistle (see Star-thistle, Malta).

Napier grass

Navarretia, needle-leaved...

Neckweed (see Speedwell,

purslane).

Needlegrass, green

Nettle, stinging

Nightshade, black

Nightshade: Cutleaf; threeflowered.

Nightshade: Silver-leaf;

purple.

Nipplewort

Nitgrass

Nutgrass

Nutgrass, yellow

Oat

Oat, common or Northern..

Oat, fatuoid (homozygous).

Oat, red or Southern

Oat, sand

Oat, slender ---

Oat, wild

Ipomoea jmrpurea.

Jacquemontia tamnifolia.

Ipomoea hederacea

Ipomoea lacunosa

Leonurus cardiaca

Pycnanthemumsv. {Koellia

sp.).

Verbascum thapsus

Cucumis melo

Brassica spp

Brassica nigra

Chorispora tenella

Brassica júncea

Hirschfeldia incana (Brassica adpressa).

Lepidium latifolium

Brassica perviridis

83

Page Figure

126

82 124

Brassica hirta (B. alba) —

Poa fendlerianaPoalongiligula-.

83

Pennisetum purpureumNavarretia intertexta

119

119

119

Stipa viridula

Urtica dioica.

Solanum nigrum^-.

Solanum triflorum..

Solanum elaeagnifoliumLapsana commums

Gastridium ventricosum.

Cyperus rotundus

Cyperus esculentus

Avena

Avena sativa

Avena

Avena byzantina

Avena strigosa

Avena barbata

Avena fatua

126

126

126

35
TESTING AGRICULTURAL AND VEGETABLE SEEDS 409

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

III, 67-68 .

Page

213

205

Oatgrass, poverty Danthonia spicata

Page Page Figure

11,35 Oatgrass, tall ... Arrhenatherum elatius

Hibiscus esculentus _.

Allium cepa

66

81

82

126

164

160

Okra- 60

Onion 57

XIII, 220 .__ Onion, wild. _ _ _ Allium vineale ______

XX, 408. _. 248 Ononis, cammock- Ononis repens -

Orach, halberd-leaved (see

Fat-hen).

XIV, 247 Orach, red-. Atriplex rosea.

XIV, 248 Orach, wedgescale . Atriplex truncata

111,66 213 Orchard grass Dactylis glomerata 60 126

XXIII, 475 Oxalis, yellow Oxalis stricta

XXXII, 689.___ Ox-eye daisy __ . Chrysanthemum leucanthemum.

XXXIII, 720--- 0xtongue, bristly _ _ - Picris echioides

235

221

220

221

221

Pakchoi Brassica chinensis 83

65

119

VI, 122 Panicgrass, blue--- -. Panicum antidotale 126

Panicum Panicum

VI, 121 Panicum, beaked __ Panicum anceps

VI, 123 Panicum, Berg Panicum bergii

Panicum, blue (see Panicgrass, blue).

Panicum, browntop (see

footnotel, p. 397).

Panicum, fall (see Witchgrass, spreading).

Panicum, Gattinger (see

Witchgrass, Gattinger).

Panicum, hairy

VI, 128 221 Panicum Jasciculatum 65 126

VI, 131. 221

221

Panicum huachucae

VI, 130 Panicum, Hillman Panicum hillmani

Panicum, spreading (see

Witchgrass, spreading).

VI, 137 221 Panicum, Texas Panicum texanum

XXIV, 505 Pansy, wild Viola tricolor

VI, 135.-.. 221 Para grass Panicum purpurascens

Petroselinum hortense (P.

crispum).

Pastinaca sativa

80

80

167

167

XXVI, 537 Parsley

Parsnip

222

222

222

222

222

223

222

249

Paspalum Paspalum. _ __

VII, 146... Paspalum, brownseed

Paspalum, bull

Paspalum plicatulum

VII, 139 Paspalum boscianum

VII, 143 Paspalum, field .. Paspalum laeve^

VII, 142 Paspalum, Florida Paspalum floridanum

VII, 144 Paspalum, ribbed. . Paspalum malacophyllum

VII, 147 Paspalum, slender Paspalum setaceum

XXI, 412 Pea, field Pisum sativum arvense

Pisum sativum

73

73

73

62

142

142

142

126

48,49

Pea, garden

Peanut Arachis hvDoaaea

VII, 149 223

250

223

Pearl millet Pennisetum glaucum

XXI, 417 Peaweed, Austrian -. _ Swainsona salsula

Pennisetum Pennisetum

XVIII, 344 Pennycress . Thlaspi arvense.

XXVIII, 590_... Pennyroyal, American

Pepper

Hedeoma pulegioides

Capsicum sp 80 167

XVII, 331 236

235

235

Peppercress, field Lepidium campestre

XVII, 322 Peppercress, hoary Cardaría draba {Lepidium

draba).

Peppercress, lens Cardaria draba var. rejjens.

Peppercress, perennial (see

Mustard, perennial).

XVII, 334 Peppergrass, American Lepidium virginicuw .-.
410 AGRICULTURE HANDBOOK NO. 30, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

XVII, 332- .

XXVI, 541 _.

XXVI, 538.

XXX, 634..

XXX, 644..

XXX, 638..

XXX, 636.-

XXX, 639...

XXX, 643.-,

XXX, 635.-

XXX, 637.-

XXX, 640.-

XXA,633.-

XXX, 641.-

XXXI, 674.

XXXI, 675.

Page

XXVI, 534-..

XXVI, 551....

XXVIII, 580..

XVI, 307

1,24.- ..-

XXXIII, 722.

XX, 393

VI, 133.

XXIII, 478.

XII, 199

XV, 272 .

1,9

VII, 157-.-

XVII, 337.

XVII, 336-

XXXI, 665.

XXXI, 663.

XXXI, 664.

204

245

201

Peppergrass, field (see Peppercress, field).

Peppergrass, prairie

Peppergrass, Virginia (see

Peppergrass, American),

Perennial mustard (see Mustard, perennial).

Pe-tsai (Chinese cabbage)...

Pimpernel, scarlet

Pimpinella, saxifrage

Plantain: Blackseed;

Rugel's; rattail.

Plantain, blond

Plantain, branching

Plantain: Braeted; bottlebrush.

Plantain: Buckhorn; narrowleaved; English; ribgrass.

Plantain, crowfoot

Plantain: Paleseed; dwarf. _.

Plantain: Psyllium; fleaseed.

Plantain, redseed

Plantain: Ripplesced; broadleaved .

Plantain, slender

irgePlumeless thistle

Plumeless thistle, ]

headed.

Poison hemlock

Poison rycgrass (see Darnel) -

Ponyfoot, creeping —

Popcorn flower...

Poppy, opium --.

Poverty-grass, three-awn—

Povertyweed (see Sumpweed, poverty)

Prairie-rocket (see Rough

blistercress).

Prairie-coneflower

Prairie-trefoil

ScaProso; broomcorn milletPumpkin -

Puncturevine

Purpletop

Pursh seepweed (see

blite).

Purslane, common

Quackgrass

Queen Anne's-lace (see Carrot, wild).

Rabbitfoot grass

Radish

Radish, wild

Ragi (see African millet).. -

Ragweed

Ragweed, giant

Ragweed, common

Ragweed: Western; perennial.

Page

Lepidium densiflormn.

Brassica pekirtensis

Anagallis arvensis

Pimpinella saxífraga.

Plantago rugelii

Plantago ovata

Plantago arenaria-.

Plantago aristata.-.

Plantago lanceolata.

Plantago coronopus

Plantago virginica

Plantago psyllium

Plantago rhodosperma..

Plantago major

Plantago pusiUa (P. elongata).

Carduus acanthoides

Carduus macrocephalus...

Conium maculât urn..

Dichondra repens

Plagiobothrys sp

Papaver somniferum..

Aristida dichotoma

Page

119

Ratibida columnaris

Lotus purshianus (L. americanus).

Panicum miliaceum

Cucúrbita pepo

Tribulus terrestris

Tridens flavus

Portulaca olerácea .

Agropyron repens..

Polypogon monspeliensis.

Raphanus sativus

Raphanus raphanistrum.

Ambrosia

Ambrosia trifida

Ambrosia artemisiifolia {A.

elatior).

Ambrosia psilostachya

Figure

126

124
TESTING AGRICULTURAL AND VEGETABLE SEEDS 411

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XXXIV, 724 .

Page

Ragwort, tansy

Rape, summer

Rape, winter

Senecio jacobaea

Page Page Figure

234

234

240

Brassica napus var. annua.

Brassicanapus var. biennis.

Daubentonia texana

83

83

119

XVII, 318— .- 119

XIX, 374 Rattlebox

Redscale (see Orach, red).. _

I, 1 197

210

212

Redtop _. Agrostis alba _ . 55

59

66

81

126

126

126

167

III, 56 Rescue grass Bromus catharticus

Chloris gayana

Rheum rhapontkum

III, 60 Rhodes grass

Rhubarb

Ribgrass; ribwort (see Plantain, buckhorn).

V, 117 Rice Oryza sativa 62

63

65

126

126

38

Rice, red Oryza sativa var

V, 118 _ Ricegrass, Indian Oryzopsis hymenoides

XIV, 261 Ringwing Cycloloma atriplicifolium—

211 Ripgut grass Bromus rigidus

XVI, 308 - Roemeria poppy Roemeria refracta

XVIIl, 349 Rose Rosa sp

XVII, 327-— - Rough blistercress Erysimum asperum

XIX, 382 243 Rough pea Lathyrus hirsutus 74 142

XIV, 267a Rough pigweed.__ .__ Amaranthus retroflexus

Rushgrass (see Dropseed,

scratch).

XII, 219 Rush, path Juncus tenuis

XIX, 379 241 Rushpea Hoffmannseggia sp

XIV, 249 Russian pigweed Axyris amaranthoides

XIV, 266 Russian-thistle Salsola kali var. tenuifolia

(S.pestifer).

Brassica napus var. napobrassica.

Sécale céréale

234 Rutabaga; Swede turnip

Rye

83

62

64

64

64

119

126

126

126

126

XI, 184 36,37

219

220

220

220

Ryegrass Lolium spp . . .

V,111 Ryegrass, Italian.. Lolium multiflorum

V, 110 Ryegrass, perennial; Eng- Lolium perenne

lish ryegrass.

Ryegrass, Persian

Ryegrass, poison (see

Darnel).

Ryegrass, Wimmera

Safflower...

V, 112 Lolium persicum

»

220 Lolium rigidum.. ._.

XXXII, 677..-. Carthamus tinctorius

XXVIII, 600_..- Sage, lanceleaf

Sage, lilac

Salvia lanceolata

XXVIIl, 601-_-. Salvia verticillata—

XX, 407

XVII, 326

248

236

Sainfoin

Salad-rocket

Onobrychis viciaefolia

Eruca sativa

74 142

Salsify

Salsify, meadow

Tragopogón porrifolius

Tragopogón pratensis

84 113

XXXIV, 733__..

Saltbush (see Orach, wedgescale) .

214 Saltgrass

214

214

Distichlis

111,71 Saltgrass: Desert; inland

Saltgrass, seashore _......

Sandbrier (see Horsenettle,

Carolina).

Sandbur, field

Distichlis stricta

111,72. Distichlis sptcata

111,63-. 211 Cenchrus pauciflorus.

Sandvine (see Milkweed,

climbing).

Sandwort, thymeleaf

Savory, catnip

XV, 276 Arenaria serpyllifolia

XXVIII, 603..- Satureja nepeta

XXVIII, 602..._ Savory, spring Satureja acinos

Savory, wild basil (see

Basil).

XXXI, 658...._ Scabiosa Scabiosa sp
412 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XXXI, 657

Page

XXVII, 569

XIV, 262

XVI, 306 — -

XII, 204 -

XII, 205 _ _

XXV, 517

XIX, 364

XX, 409

XXX, 632

239

248

XXI, 414

XIX, 365.

XXVI, 536

249

239

XXXII, 688---.

XXVII, 567

11,44 208

XIII, 231

V, 119

XXX, 651

XXIV, 486

V, 103.. -

XI, 188-193

XI, 187..

230

XIII, 235

XIII, 236

XXXIV, 728 .

XXXIV, 726—.

XXXIV, 727

XIX, 377

XXVIIr, 581-.-

241

XXX, 630

XXX, 629

XXX, 631

XV, 269 . _

XII, 216

XII, 210

XII, 211

XII, 208

XII, 209

XXXII, 687-.._

Seabiosa, field...

Scaleweed (see Pennycress)..

Scorpionweed

Sea-blite

Sea-poppySedge, hairyseed

Seedbox

Seepweed, Pursh (see Seablite).

Selfheal (see Heal-all)

Sensitive-pea

Serradella

Sesame

Sicklepod

Sickleweed

Sida, spiny (see Mallow,

prickly).

Sidalcea, meadow (see

Checsemallow, plains).

Singletary pea (see Rough

pea).

Skeleton weed

Skunkweed _--

Sloughgrass, American

Smartweed, common

Smartweed, pale (see Ladysthumb, pale).

Smartweed, Pennsylvania

(see Ladysthumb, bigseed).

Smartweed, spotted (see

Ladysthumb).

Smilo --- --

Snowberry, Western

Snow-on-the-mountain- -. _.

Soft grass.

Sorghum

Sorghum-Sudan hybrids. _.

Sorrel, garden

Sorrel: Sheep; field; red

Sowthistle, common

Sowthistle: Perennial; creeping.

Sowthistle: Spiny; prickly..

Soybean

Spatulate fog-fruit

Speedwell, corn

Speedwell, field

Speedwell, purslane

Spiderling

Spiderwort, Virginia

Spike redtop (see Bentgrass,

spike).

Spikerush, autumn..

Spikerush, Baldwin

Spikerush, blunt

Spikerush, slender

Spikeweed

Spinach, common.

Seabiosa arvensis..

Page Page

AUocarya sp

Suaeda depressa (Dondia

depressa).

Olaudum corniculatum

Carex festucacea

Carex trichocarpa

Ludwigia alternifoUa

Cassia nictitans

Ornithopus sativus..

Sesamum orientale..

Sesbania exaltata—

Cassia tora

Falcaría rivini

Chondrilla júncea

Navarretia squarrosa

Beckmannia syñgachne.

Polygonum hydropiper..

Oryzopsis miliacea

Symphoricarpos occidentalis.

Euphorbia marginata

Holcus mollis

Sorghum vulgäre

65 126

Rumex acetosa

Rumex acetosella...

Sonchus oleraceusSonchus arvensis...

126

167

Sonchus asper

Glycine max

Lippia nodiflora

Veronica arvensis

Veronica agrestis

Veronica peregrina

Boerhaavia erecta

Tradescantia virginiana.

73

Fimbristylis autumnalis..

Fimbristylis baldwiniana..

Eleocharis obtusa

Eleocharis tenuis

Centromadia sp

Spinacia olerácea 84 107 26

Figure

41,42
TESTING AGRICULTURAL AND VEGETABLE SEEDS 413

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION-Continued

Identification Common name Botanical name Purity Germination

Plate Page

Spinach, New Zealand

Spreading pigweed. _

Tetragonia expansa

Amaranthus graecizans

Page

84

Page

107

Figure

XV, 268

XXIII, 482 Spurge, flowering Euphorbia coroUata

XXIII, 483 Spurge, leafy Euphorbia esula...

XXIV, 487 Spurge, nodding Euphorbia nutans

XXIV, 488 _ Spm-ge, spotted Euphorbia supina (E.

macúlala).

XXIV, Euphorbia helioscopia. 485 Spurge, sun __

XXIV, 484 Spurge, toothed _. Euphorbia dentata

XVI, 292 Spurry, corn _ Spergula arvensis

XVI, 293 Spurry, wingsecd.. _ Spergula pentandra

Squash Cucúrbita moschata.

C maxima

82

82

124

124

XXXII, 680.... Star-thistle, Iberian Centaurea ibérica

XXX11,683...- Star-thistle, Malta... Centaurea melitensis

XXXIl, 678.... Star-thistle, purple Centaurea calcitrapa

XXX]I,685-... Star-thistle, scabiosa

Star-thistle, spotted (see

Knapweed, spotted).

Star-thistle, yellow.

Centaurea scabiosa

XXXII, 686.... Centaurea solstitialis

XV. 274 Starwort, little

Stickseed, European

Stickseed: Western; hairy_..

Stinkgrass

Stellaria graminea (Alsine

graminea)

XXVII, 576-.... Lappula echinata

XXVII, 577

216

Lappula occidentalis

IV, 86 Eragrostis cilianensis

Stinkweed (seePennycress).

XXIV, 504 St. Johnswort Hypericum perforatum

XXIX. 622 "Stone cells" in Solanum

fruits.

XVm, 348 Strawberryweed Potentilla monspeliensis

XI, 186. _. 230

241

Sudan grass: Common;sweet;

Tift.

Sulla

Sorghum sudanense

Hedysarum coronarium

70 126

XIX, 378

XIV, 264 Summer cypress. Kochia scoparia

XXXIll, 710... Sumpweed, bigleaf Iva xanthifolia

XXXIII, 708.._ Sumpweed, poverty Iva axillaris...

XXXIII, 709__. Sumpweed, rough Iva ciliata

XXXIII, 702... Sunflower, common Helianthus annuus

Melilotus

84 113

247

247

247

Sweetclover

XX, 404 Sweetclover, white-blossom.

Sweetclover, yellow-blossom.

Swine-cress (see Wart-cress).

Swiss chard

Melilotus alba 75

75

142

142 XX, 405. _ Melilotus officinalis

Beta vulgaris var. cicla 84

65

107

126 VI, 138 222 Switch i^rass _

Tall hedge mustard (see

Tumblemustard).

Tall indigo fsee Sesbania)...

XIX, 384 243

237

Tangier pea Lathyrus tingitanus

XXXIV. 729.. . Tansy, common Tanacetum vulgäre... .

Tansy mustard Sisymbrium irio

XXXIV, 724..... Tansy ragwort Senecio jacobaea

XXXIII, 718.._ Tarweed, Chilean Madia sativa

XXXIII, 717... Tarweed, cluster Madia glomerata..

XXXin, 704... Tarweed, hay-field Hemizonia luzulaefolia...

XXXI, 656 Teasel, wild Dipsacus sylvestris

216 TeflE Eragrostis tef

Texas-millet (see Panicum, .

Texas),

XXXII, 692.... Thistle, bull Cirsium vulgäre (C. lance- .

olatum).

XXX1I,691 Thistle, Canada Cirsium arvense _

XXXI, 673.. Thistle, curly Carduus crispus

9^7116--52——28
414 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification

Plate

XXXII, 676,

XXV, 529_-

1,24

XXIIl, 479_

1,8

XIV, 259-.-

XIV, 260.

V,120.

XXIX, 024 _

XXV, 52:^-

xvI,3ll---

xvII, 328 _

XX, 394....

XX, 395-

XX, 391.

XX, 393.

xii,2(:o.

VII, 158

XVIIT, 341.

XIV, 2()7b.,

XXIll. 481.

XVX, 315..

V,116

VII, 148 _-

XXI, 415.

V, 103

V, 102.....

XXIV, 481

XXXI, 65

11,33

XXVIII, 583-

XXVIII, 582..

XXVIII, 584..

;XXVIII, 585..

Page

204

198

245

245

245

245

245

254

235

220

222

249

203

204

204

Common name Botanical name

Thistle, Italian

Thistle, Turkistan (see Kiiapweed, Russian).

Thorn-apple (see Jimsonweed).

Thoroughwax, roundleaf

Three-awn, poverty..

Three-seeded mercury

Ticklegrass ---

Tickseed

Tickseed, hairy

Ticvine (see Bindweed,

field).

Timothy

Tipton-weed (see St. Johnswort).

Toadflax, roundleaf

Toadflax, yellow (see

Butter-and-eggs).

Tocalote (see Star-thistle,

Malta).

Tomato, common

Tomato, husk

Toothpick plant _ _

Towermustard

Treacle-mustard

Trefoil

Trefoil, big

Trefoil, big-.

Trefoil, birdsfoot

Trefoil, prairie.

Trigonella

Trisetum, yellow

Trompillo (see Nightshade,

silverleaf).

Tumblegrass .-.

Tumblcmustard

Tumbling pigweed -

Turkey mullehi

Turkistan thistle (see Knapweed, Russian).

Turnii); turnip-rape; wild

turnip.

Tussack grass

Vasey grass

Velvetbean; Florida velvetbean.

Vclvetgrass, German

Velvetgrass

Velvet-leaf . -

Vonus's-looking-glass

Vernalgrass

Vcrnilgrass, annual

Vernalgrass, sweet

Vervain..

Vervain, blue

Vervain, hoary

Vervain, white .- -

Carduus pycnocephalus.

Purity Germination

Page

Bupleurum rotundifoUum.

Aristida dichotoma

Acalypha virginica

Agrostis scabra— -

Conspermum hyssopifolium.

Conspermum villosum

Phleum pratenseKickzia spuria.

Lycopersicon esculentum...

Physalts pubescens

Ammi visnaga

Arabis glabra

Erysimum cheiranthoides...

Lotus

Lotus uliginosus var. villosus.

Lotus uliginosus var. glabrisculus.

Lotus corniculatus

Lotus pu rshianus

Trigonella

Trisetum flavescens

66

Page Figure

167

167

Schedonnardus paniculatus

Sisymbrium aUissimum _..

Amaranthus albus

Eremocarpus seliger us

Brassica campestris or B.

rapa.

Nassella trichotoma

Paspalum urvillei

Stizolobium deeringianum

Holcus mollis

Holcus lanatus

Abutilón theophrasti

Specularia perfoUata

Anthoxanthum

Anthoxanthum aristatum.

Anthoxanthum odoratum-.

Verbena officinalis

Verbena hastata

Verbena stricta

Verbena urticaefoUa

75

83

43

' 62

54, 55

58 126

73 142

126
TESTING AGRICULTURAL AND VEGETABLE SEEDS 415

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XXIII, 460.

XXIII, 462.

XXII, 454..

XXIII, 465.

XXII, 455..

XXIII, 463-464

XXII, 459

XXIII, 461

XXII, 453

XXIII, 466

XXII, 457

XIX, 381-

VI, 134....

XXVI, 533..

XII, 201.

I, 13.

I, 16-.

1,11..

1,14.

I, 12..

1,10

XV, 279........

XXVIII, 594-.

Page

255

257

257

257

257

257

256

257

257

257

257

257

257

256

242

243

243

243

242

222

236

198

200

201

200

200

200

201

200

200

200

201

200

201

232

Vetch

Vetch, American

Vetch, bird

Vetch, common

Vetch, cow (see Vetch, bird).

Vetch, fourseed

Vetch, hairy

Vetch, Hungarian

Vetch, Monantha

Vetch, narrowleaf

Vetch, purple

Vetch, showy

Vetch, tiny

Vetch, woollypod

Vetch, yellow

Vetchling

Vetchling

Vetchling (see Groundnut

pea).

Vetchling, low

Vetchling, slender

Vetchling yellow _

Vine-mesquite

Wallflower, western (see

Rough blistercress).

Wart-cress; swine's-cress

Water-hemlock, spotted

Watermelon

Western bluest em (see

Wheatgrass, Western).

Wheat (Common; club;

Polish, including spelt

andemmer).

Wheatgrass

Wheatgrass, bearded

Wheatgrass, beardless. _

Wheatgrass, Fairway crested..

Wheatgrass, hairy intermediate.

Wheatgrass, hairy western...

Wheatgrass, intermediate

(including Ree wheatWheatgrass, pubescent (see

Wheatgrass, hairy intermediate).

Wheatgrass, slender

Wheatgrass, standardcrested.

Wheatgrass, streambank

Wheatgrass, tall

Wheatgrass, thickspike

Wheatgrass, Western

White cockle; whitecampion..

White horehound

White horse nettle (see

Nightshade, silver-leaf).

Vicia spp

Vicia americanaVicia cracca

Vicia sativa

Page Page

Vicia tetrasperma

Vicia villosa

Vicia pannonica

Vicia articulata (V. monantha).

Vicia angustîfolia

Vicia atropurpúrea

Vicia grandiflora

Vicia hirsuta

Vicia das¿,carpa

Vicia lútea

Lathyrus

Lathyrus pusillus

79

142

142

142

142

142

79

Lathyrus pusillus.-.

Lathyrus stipularis.

Lathyrus aphaca

Panicum obtusum--

Coronopus didymus..

Cicuta maculata

Citrullus vulgaris 82

Triticum spp_. 62

Agropyron spp

Agropyron subsecundum^.

Agropyron inerme

Agropyron cristatum

Agropyron trichophorum.

Agropyron smithii var.

molle.

Agropyron intermedium....

Agropyron trachycaulum

(A. paiiciflorum).

Agropyron desertor um

(formerly A. cristatum)

Agropyron riparium

Agropyron elongatum

Agropyron dasystachyum...

Agropyron smithii

Lychnis alba

Marrubium vulgäre

55

124

Figure

126

126
416 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

INDEX FOR IDENTIFICATION, PURITY, AND GERMINATION—Continued

Identification Common name Botanical name Purity Germination

Plate

XVII, 322, 323—

XXV, 524.

XV, 270-

XXVI, 554..

IV, 82.

IV, 81.

IV, 83..

IV, 84.

IT, 34..

Ill, 59-

XVI, 313..

XVI, 312.

VII, 141.,.

VI, 125..

V, 109...

VI, 129..

VI, 127..

VI, 126..

XII, 217.-.-

XII, 218

XXIII, 475.

XXXI, 661-

XVIII, 340..

X, 175

XIX, 381-

XII, 202,203. .

Page

235

258

214

215

215

215

215

215

215

204

212

222

221

219

221

221

221

237

229

231

White-leaved povertyweed

(see Bur-sage, skeletonleaf).

Whitetop

(see also: Hoary cress;

Perennial peppercress; Daisy fleabane).

Wild chervil

Wild flax (see Falseflax, big

seed).

Wild four-o'clock

Wild madder (see Bedstraw,

white).

Wild potato vine.

Wild-rye.

Wild-rye, beardless.

Wild-rye, blue

Wild-rye, Canada

Wild-rye, riverbank

Wild-rye, Russian

Wild-rye, Virginia. _

Willow-herb

Windgrass

Windmill grass

Winged pigweed (see Ringwing).

Wintercress, common

Wintercress, early -

Wiregrass .-.

Witchgrass (see Quackgrass).

Witchgrass, common

Witchgrass, fall

Witchgrass, Gattinger

Witchgrass, spreading

Witchgrass, western

Wolfberry (see Snowberry,

Western).

Wood meadow gi-ass (see

Bluegrass, wood).

Woodrush, field

Woodrush, grove.. —

Wood sorrel; yellow wood

sorrel.

Wormseed mustard (see

Treacle-mustard).

Woundwort (see Betony,

marsh).

Yarrow

Yellowcress, creeping -.

Yellow foxtail

Yellow hop-clover (see Clover, yellow).

Yellow pea— _

Yellow rocket (see Wintercress, common).

Yellow trefoil (see Medic,

black).

Yorkshire fog (see VelvetZoysia.

Page Page Figure

Cardaría.

Anthriscus sylvestrisMirabilis nyctaginea.

Ipomoea pandurata.

Elymus spp

Elymus triticoides—

Elymus glaucus

Elymus canadensis..

Elymus riparius

Elymusjunceus

Elymus virginicus. _

Epilobium spp

Apera spica-venti. _.

Chloris acicularis...

126

Bûrbarea vulgaris

Barbarea verna

Paspalum distichum.

Panicum capillare

Leptoloma cognatum

Panicum gattingeri

Panicum dichotomiflorurnPanicum capillare var. occidentale.

Luzula campestrisLuzula luzuloides—

Oxalis stricta.

Achillea millefolium.

Rorippa sylvestris—

Setaria lutescens

Lathyrus aphaca..

Zoysia-. 65
LIST OF BOTANICAL AND COMMON NAMES

This list gives the common name equivalents for certain species

illustrated in the seed plates, but not included in the keys and

descriptions. The common names of other species included in the

lists of botanical and plant names, beginning on pages 373 and 395,

respectively, may be found under the heading "Identification of

Seeds," pages 194 to 261.

Botanical Name. Common Name

Ahutilon theophrasti Velvet-leaf

Acalypha virginica ^ Three-seeded mercury

Achillea millefoUum. Yarrow

Achyrachaena mollis Blowwives

Aethusa cynapmm Fool's parsley

Agrostemma githago Corncockle

Ajuga chamaepitys Ground bugle

Allium vineale Wild garlic

Allocarya sp Scorpionweed

Althaea hirsuta No common name

Alyssum alpssoicles Pale alyssum

Amaranthus alhus Rough pigweed

Amaranthus graceizans . Spreading pigweed

Am^aranthus retrofleams Redroot amaranth

Ambrosia artemisiifolia Common ragweed

Amhrosia psilostachya Perennial ragweed

Ambrosia trifida Giant ragweed

Ammi majus Greater ammi

Ammi visnaga Toothpick plant

Amsinckia interm^edia Coast fiddleneck

Amsinckia tesselata Fiddleneck

AnagalUs arvensis Scarlet pimpernel

Anem^one canadensis Meadow anemone

Anthémis arvensis Corn-chamomile

Anthémis cotula . Dogfennel

Anthémis tinctoria Yellow chamomile

Anthriscus sylvestris Wild chervil

Apium ammi Wild celery

Apiuin segetum No common name

Aplopappus ciliatus Hairy goldenweed

Apocynum androsaemifolium Spreading dogbane

Apocynum cannaMnum . . Hemp dogbane

Arahis glahra Towermustard

Arctium lappa Great burdock

Arenaria serpyllifolia Thymeleaf sandwort

Arnoseris minima Lamb-succory

Asclepias galioides „ Whorled milkweed

Asclepias m^exicana Mexican milkweed

Asclepias syriaca Common milkweed

Asclepias tuberosa Butterflyweed

Asperugo procumdens German madwort

Atriplex patula var. hastata Fat-hen

Atriplew rosea Red orach

Atriplex truncata Wedgescale orach

417
418 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Botanical Name Common Name

Axyris amaranthoides Russian pigweed

Ballota nigra Black liorehound

Barbarea verna Early wintercress

Barbarea vulgarls Bitter wintercress

Bassia hyssopifoUa Five-hook bassia

Berteroa incana Hoary alyssum

Boerhaavia erecta Spiderling

Boisdtwalia densiflora Dense-flowered Boisduvalia

Boisduvalia stricta Stricta Boisduvalia

Brauneria angustifolia Purple coneflower

Brodiaea coronaria Harvest brodiaea

Brodiaea grandiflora Large-flowered brodiaea

Bunium bulbocastrum Earthnut

Bupleurum protractum Thoroughwax

Bupleurum rotundifoUum Roundleaf thoroughwax

Bupleuriim tenuissimum Thoroughwax

Camdina microcarpa Littleseed falseflax

Camelina sativa Bigseed falseflax

Cannabis sativa Hemp

Caperonia palustris No common name

Carduus acanthoides Plumeless thistle

Carduus crispus Curly thistle

Carduus macrocephalus Large-headed plumeless thistle

Carduus pycnocephalus Italian thistle

Garex festucacea Sedge

Carex trichocarpa Hairyseed sedge

Carthamus tinctorius Saiflower

Carum carvi Caraway

Centaurea calcitrapa Purple star-thistle

Centaurea cyanus Bachelor's-button

Centaurea ibérica Iberian star-thistle

Centaurea jacea Brownscale knapweed

Centaurea maculosa Spotted knapweed

Centaurea melitensis Malta star-thistle

Centaurea picris Russian-thistle

Centaurea scabiosa Scabiosa star-thisle

Centaurea solstitialis Yellow star-thistle

Centromadia sp. Spikeweed

Cephalaria transylvanica Cephalaria

Cerastium vulgatum Big mouse-ear chickweed

Chaerophyllum sp. Chorvil

Chenopodium album Lambsquarters

Chenopodium' berlandieri Pitseed goosefoot

Chenopodium hirdnum No common name

Chenopodium hybridum Mapleleaf goosefoot

Chenopodium hybridum var. gigantospermum Bigseed goosefoot

Chenopodium leptophyllum Narrowleaf goosefoot

Chenopodium murale Nettleleaf goosefoot

Chenopodium rubrum Red goosefoot

Chondrilla júncea Skeletonweed

Chrysanthemum leucanthemum var. pinnatifi' Ox-eye daisy

dum.

Cichorium intybus Chicory

Cicuta maculata Spotted waterhemlock

Cirsium arvense Canada thistle

Cirsium vulgäre Bull thistle

Collomia gracilis Gilia

Collomia grandiflora Bigflower gilia

Commelina communis Common dayflower

Conium tnaculatum Poisonhemlock

Corispermum hyssopifoHum Tickseed

Corispermum villosum Hairy tickseed

Crépis capillaris Smooth hawksbeard

Crépis setosa Hairy hawksbeard
TESTING AGRICULTURAL AND VEGETABLE SEEDS 419

Botanical Naine Common Name

Cpcloloma atripUcifoUum Ringwing

Gynodon dactylon Bermuda grass

Cyperus esculentus . Yellow nutgrass

Cyperiis rotundus Nutgrass

Datura stramonium Jimsonweed

Daucus carota Carrot; wild carrot

Delphinium consolida Field larkspur

Delphinium menzicsii Menzies larkspur

Dianthus armería Deptford pink

Dlchondra repens Ponyfoot

Digitaria filiformis Slender crabgrass

Diijitaria ischaemum , Smooth crabgrass

Digitaria sanguinalis Large crabgrass

Diodia teres Rough buttonweed

Diodia virginiana Virginia buttonweed

Dipsacus sylvestris Wild teasel

Echium vulgäre . Blueweed

Eleocharis obtusa Blunt spikerush

Eleocharis tenuis Slender spikerush

Eleusine coracana African millet

Eleusine indica Goosegrass

Erechtites hieracifolia Burnweed

Erechtites prenanthoides Australian burnweed

Eremocarpus setigerus Turkey mullein

Ercmochloa ophiuroides . Centipede grass

Erigeron annuus Daisy fleabane

Erigeron canadensis Horseweed

Eriochloa punctata Louisiana cupgrass

Erodium cicutarium Alfilaria

Erysinmm asperum Rough blistercress

Erysimum cheiranthoides Treacle-mustard

Erysimum inconspicuum Smallflower Erysimum

Eschscholtzia californica California-poppy

Euphorbia corollata Flowering spurge

Euphorhia dentata Toothed spurge

Euphorbia esida Leafy spurge

Euphorbia helioscopia Sun spurge

Euphorbia marginata Snow-on-the-mountain

Euphorbia nutans . Nodding spurge

Euphorbia supina Spotted spurge

Euphrasia sp. Eyebright

Falcaría rivini Sickleweed

Fimbristylis autumnalis Autumn spikerush

Fimbristylis baldwiniana Baldwin spikerush

Franseria discolor Skeletonleaf bur-sage

Franseria tenuifolia Slimweed bur-sage

Fumaria officinalis Common fumitory

Galega officinalis Common goatsrue

Galeopsis ladanum . Red hempnettle

Galeopsis tetrahit. Bristlestem hempnettle

Galinsoga parviflora Galinsoga

Galium aparine Cleavers

Galium mollugo White bedstraw

Gastridium iwntricosum Nitgrass

Gaura coccínea Scarlet gaura

Gaura odorata Scented gaura

Gaura sinuata Wavyleaved gaura

Gaura villosa Hairy gaura

Geranium caroUnianum Carolina cranesbill

Geranium columbinum Longstalk cranesbill

Geranium dissectum Cutleaf cranesbill

Geranium molle Dovefoot cranesbill

Geranium pusillum Small cranesbill

Gemn sp : Avens

Qilia Gapitata^^_^^_^__^ ^__,^^^_,_j' ,_ Globe gilia
420 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Botanical Name Common Name

Glaucium, corniculatiim Sea-pc^py

Glpceria fluitans Mannagrass

Glyoeria grandis American mannagrass

Glyceria striata Fowl mannagrass

Godetia tenella Godetia

Gonolohus laevis . Climbing milkweed

Grindelia squarrosa Curleycup giimweed

Hackelochloa granularis Lizard-tail

Halogeton glomeratus Halogeton

Hedeoma pulegioides American pennyroyal

Helianthus annuiis Common sunflower; wild sunflower.

Helianthus ciliaris Texas blueweed

Heliotropimn curassavicum Salt heliotrope

Heliotropium europaeum European heliotrope

Hemisonia luzulaefolia Hay-field tarweed

Hete?^otheca grandiflora No common name

Hibiscus trionum Flow^er-of-an-hour

Hieracium aurantiacum Orange hawkweed

Hirschfeldia incana Hairy mustard

Holcus lanatus —_ Velvetgrass

Holcus mollis German velvetgrass

Houstonia purpurea Purple bluets

Hyoscyamus niger — Black henbane

Hypericum perforatum St. Johnswort

Hypochaeris radicata — Spotted cats-ear

Iva axillaris Poverty sumpweed

Iva ciliata Rough sumpweed

Iva œanthifoUa Bigleaf sumpweed

Juncus tenuis Path rush

Kickxia spuria Roundleaf toadflax

Kochia scoparia Summer cypress

Kyllinga sp. Kyllinga

Lactuca canadensis Tall lettuce

Lactuca pulchella Blue lettuce

Lactuca scariola var. integrifolia Prickly lettuce

Lamium amplexicaule Henbit

Lappula echinata European stickseed

Lappula occidentalis - Western stickseed

Lapsana communis Nipplewort

Leontodón autumnalis Fall-dandelion

Leontodón nudicaulis Rough hawkbit

Leonurtis cardiaca Motherwort

Lepidium densiflorum^^ Prairie peppergrass

Lepidium virginicum American peppergrass

Linaria vulgaris Butter-and-eggs

Linum usitatissimum Flax

Linum virginianum Woodland flax

Lippia nodiflora Spatulate fog-fruit

Lithospermum arvense Field gromwell

Lohelia inflata Indian-tobacco

Ludwigia alternißora Seedbox

Luzula campestris Field woodrush

Luzula luzuloides Grove woodrush

Lycopus virginicus American bugleweed

Lythrum hyssopifolia Hyssop loosestrife

Madia glomerata Cluster tarweed

Madia sativa Chilean tarweed

Malva moschata Musk mallow

Malva parviflora Little mallow

Malva rotundifolia Running mallow

Malva sylvestris High mallow
TESTING AGRICULTURAL AND VEGETABLE SEEDS 421

Botanical Name Common Name

Malvastrum coromandeUanum No common name

MarruMum vulgäre White horehound

Matricaria inodora False-camomile

Melampyrum arvense . Cow wheat

Melinis minutiflora Molasses grass

Melochia corchorifolia No common name

Mentha arvensis Field mint

Mentzelia alUcaulis Whitestem Mentzelia

Mentzelia dispersa Bushy Mentzelia

Mentzelia nuda Bractless Mentzelia

MiraUUs nyctaginea Wild four-o'clock

Moldávica parviflora American dragonhead

Molinia caerulea Moorgrass

Muscari comosum Tassel grape-hyacinth

Myosotis arvensis Forget-me-not

Navarretia interteœta Needleleaved Navarretia

Navarretia squarrosa Skunkweed

Nepeta cataría . Catnip

NesUa paniculata Ball mustard »

Nigella damescena Love-in-a-mist

Nigella sativa Garden fennelflower

Oenothera Hennis Evening-primrose

Oenothera laciniata- Cutleaf evening-primrose

Oenothera parodiana No common name

Oryza sativa Rice

Oryzopsis hymenoides . Indian ricegrass

Oryzopsis miliacea Smilo

Osealis stricta Yellow oxalis

Fapaver somniferum Opium poppy

Petroselinum crispum (P. hortense)- Parsley

Phleum pratense Timothy

Physalis lohata Purple-flowered groundcherry

Physalis longifoUa Perennial groundcherry

Physalis swbgla'brata Taperleaf groundcherry

Picris echioides Bristly oxtongue

Picris hieracioides Hawkweed picris

Pimpinella saxifraga Saxifrage pimpernella

Plagiohothrys sp. — Popcorn flower

Plantago arenaria Branching plantain

Plantago aristata Bracted plantain

Plantago coronopus Crowfoot plantain

Plantago hirtella No common name

Plantago lanceolata Buckhorn plantain

Plantago major Broadleaf plantain

Plantago ovata Blond plantain

Plantago psyllium Psyllium plantain

Plantago pusilla Slender plantain

Plantago rhodosperma Redseed plantain

Plantago rugelii Blackseed plantain

Plantago virginica Paleseed plantain

Polygonum argyrocoleon Silversheath knotweed

Polygonum aviculare Knotweed

Polygonum convolvulus Black bindweed

Polygonum hydropiper Common smartweed

Polygonum lapathifolium Pale ladysthumb

Polygonum pensylvanicum Bigseed ladysthumb

Polygonum persicaria Ladysthumb

Polypogon monspeliensis Rabbitfoot grass

Portulaca olerácea Common purslane

Potentilla canadensis . Oldfleld cinquefoil

Potentilla monspeliensis Strawberryweed

Prunella vulgaris Heal-all

Pycnanthemum sp Mountain-mint

Ranunculus acris Tall buttercup

Ranunculus hulbosus Bulbous buttercup
422 AGRICULTURE HANDBOOK NO. 3 0, U. S. DEPT. OF AGRICULTURE

Botanical Name Common Name

Ranunculus parviflorus _ Small-flowered buttercup

Ranunculus repens Creeping buttercup

Ranunculus sardous Hairy buttercup

Raphanus raphanistrum Wild radish

Raphanus sativus ^ Radish

Rapistrum rugosum No common name

Ratihida columnaris Prairie coneflower

Reseda lutea Base-rocket

Rhynohospora macrostachya Horned rush

Roemeria refracta Roemeria poppy

Rosa sp. Wild rose

RouMeva multifida Flatweed

RuMis sp. Blackberry

Rudheckia hirta Black-eyed-susan

Rumex acetosa Sorrel ; garden sorrel

Rumex acetosella Sheep sorrel

Rumex altissimus Peach-leaved dock

Rumex conglomeratus Clustered dock

Rumex crispus-^ Curly dock

Rumex oUusifoUus Broad-leaved dock

Rumex occidentalis Western dock

Rumex persicarioides Golden dock

Rumex pulcher Fiddleleaf dock

Rumex salicifolius Willow-leaved dock

Rumex venosus Veiny dock

Salsola kali var. tenuifoUa Russian-thistle

Salvia lanceolata . Lanceleaf sage

Salma verticillata Lilac sage

Sanguisorba annua Prairie burnet

Sanguisorba minor Little burnet

Saponaria vaccaria Cowcockle

Satureja acinos— Spring savory

Satureja nepeta Catnip savory

Satureja vulgaris Basil

ScaUosa arvensis Field scabiosa

ScaUosa sp Scabiosa

Schedonnardus paniculatus Tumblegrass

Scirpus sp. . Bulrush

Scleranthus annuus Knawel

Scrophularia marilandica American figwort

Sécale céréale Rye

Senecio jacobaea Tansy ragwort

Senecio vulgaris : Common groundsel

Sesamum orientale Sesame

Sherardia arvensis Field madder

Sida hederacea Alkali mallow

Sida spinosa Prickly mallow

Sidalcea campestris Plains cheesemallow

Sidalcea hendersonii Henderson's cheesemallow

Sideritis montana No common name

Sidopsis hispida Yellow false-mallow

Sisymbrium altissimum Tumblemustard

Sisymbrium oßcinale Hedgemustard

Sisyrinchium sp. Blue-eyed-grass

Solanum carolinense Horsenettle

Solanum elaeagnifolium Silver-leaf nightshade

Solanum nigrum Black nightshade

Solanum rostratum Buffalo-bur

Solanum triflorum Cutleaf nightshade

Sonchus arvensis ^ Perennial sowthistle

Sonchus asper Spiny sowthistle

Sonchus oleraceus Common sowthistle

Specularia perfoliata— Venus's-looking-glass

Spergula arvensis Corn spurry

Spergula pentandra Wingseed spurry
TESTING AGRICULTURAL AND VEGETABLE SEEDS 423

Botanical Name Common Name

Spliaeralcea coccínea Scarlet globemallow

Stachys annua E'leld betony

macliys palustris Marsh betony

mellaría gramínea Little starwort

Stellaria media Common chiekweed

Stipa vlridula Green needlegrass

Sudeda depressa Sea-blite

Symphoricarpos occidentalis-— Western snowberry

Tanacetum vulgäre S^"^°^^^i ^^^^^ ^ r

Taraœacum erythrospermmn lied-seeaed dandelion

Taraxacum ofßcinaJe *- Dandelion

TeesdaUa nu'dicaulis No common name

Teucrium hotrys Cutleaf germander

Teucrmm canadense American germander

Thalictrum sp Meadowrue

Thelesperma sp. Greenthread

Thlaspi arvense Pennycress

Torilis anthrisGUS Erect hedgeparsley

ToriUs nodosa Knotted hedgeparsley

Tradescantia virginiana Virginia spiderwort

Tragopogón pratensis Meadow salsify

Triayithema portulacastrum Horse-purslane

Tribulus terrestris Puncturevine

Trichostema dichotomnm Forked bluecurls

Trichostema lanceolattim Vinegar bluecurls

Tridens flavas Purpletop

Trisetiim flavescens Yellow trisetum

Triticum aestivum Wheat

Urtica dioica Stinging nettle

Valerianella dentata Toothed cornsalad

Valerianella eriocarpa Italian cornsalad

Valerianella locusta var. olitoria _—__ Cornsalad

Verhascum thapsus Common mullein

Verhena liastata Blue vervain

Verbena offlcinalis Vervain

Verbena stricta Hoary vervain

Verbena urticaefolia White vervain

Vernonia nove'boracensis New York ironweed

Veronica agrestis Field speedwell

Veronica arvensis Corn speedwell

Veronica peregrina Purslane speedwell

Viola tricolor A^ild pansy

Xeranthemum cylindraceum Cylinder immortelle

INDEX

Abnormal seedlings, causes

Abutilón

Acalypha

Achillea

Achyrachaena

Adesmia

Adesmia

Adzuki bean 73, 142,

Aeschynomene

Aethusa

African millet

Agropyron 55, 127,

Agrostemma

Agrostis 55, 127,

Aizoaceae (carpetweed family) :

dormancy treatments._-

kinds of seed

seedling interpretation..

substrata for tests

Aira

Air-oven methods

Alabama White lupine

Alfalfa 77, 142, 246,

Alfilaria 82.167,

Ajuga

Alhagi

Alkali bluegrass

Alkali mallow

Alkali sacaton

Allionia

Allium 82,160,

Allocarya

Alopecurus 66, 128,

Alsike clover 77,142,

Alsine

Althaea

Alyce clover 77,

Alysicarpus 77, 142,

Alyssum

Alyssum 395,

Amaranth

Amaranthus

Ambrosia

American bugleweed

American dragonhead

American figwort

American germander

American mannagrass

American pennyroyal

American peppergrass

American sloughgrass

American vetch

Ammi

Ammi

Amsinckia

Anagallis

Analysis of the seed

Andropogon 57, 127,

Anemone

Anemone

Angleton grass

Page

97

373, 417

373, 417

373, 417

373,417

237, 373

237

248, 395

238, 373

373, 417

395, 419

198, 373

373, 417

196, 373

_ 107

107

- 109

_ 108

201, 373

_ 183

246

295, 395

395, 419

374, 417

238, 374

226, 396

407, 422

231, 395

._ 374

374, 417

374, 417

202, 374

250, 253

._ 374

374, 417

142, 238

238, 374

374, 417

417, 418

395, 417

374, 417

374, 417

398, 420

402, 421

403, 422

404, 423

407, 420

409, 420

409, 420

208

256, 257

374, 417

395, 417

374, 417

374, 417

329

202, 374

374, 417

395, 417

202, 395

Page

Annual bluegrass 67, 127, 226, 396

Annual rape 83, 119

Annual vernalgrass 204, 414

Anthémis 374, 417

Anthoxanthum 66, 128, 203, 374

Anthriscus 375, 417

Anthyllis 238, 375

Apargia 375

Apera 204, 375

Apium - 80, 167, 375, 417

Aplopappus 375, 417

Apocynum 375, 417

Arabis 375, 417

Arachis 73, 143, 375

Arctium 375, 417

Arenaria 375, 417

Aristida 204, 375

Arnoseris 375, 417

Arrhenatherum 66, 128, 204, 375

Artichoke 84,113,395

Asclepias 375, 417

Asia poppy 395

Asparagus 82, 160, 375

Asparagus __-_ 82, 160,395

Asparagus bean 73, 142, 395

Asperugo 375, 417

Astoria bentgrass 55, 127, 196, 396

Astragalus 238, 375

Atriplex 375, 417

Australian bluestem 203, 397

Australian burnweed 419

Austrian peaweed 250, 409

Austrian winter pea 249

Autumn spikerush 419

Avena 57, 126, 205, 375

Avens 395, 419

Axonopus 58, 127, 208, 375

Axyris 375,418

Bachelor's-button 395, 418

Bahia grass 58, 127, 222, 395

Baldwin spikerush 412, 419

Ball clover 250,252

Ballcress 235,395

Ball mustard 395,421

Balloon mustard 395

Ballota 376,418

Barbarea 376,418

Barbed witchgrass 221

Barkhausia 376

Barley 62, 126,218,219,395

Barnaby's thistle 395

Barnyard grass 214, 395

Barren chess 211, 399

Base-rocket 395,422

Basil 395, 422

Basil-thyme 395

Bassia 376,418

Bassia 395,418

Beaked panicum 221, 409

Bean 73, 142, 248, 294, 395

425
426 INDEX

Page

Beardgrass 202, 396, 417

Beardless wild-rye 215, 416

Beckmannia 208, 376

Bedstraw 396, 419

Beet 84, 107, 294, 396

Beet seed washer 35

Beggarweed 74, 142,241,396

Belvedere 396

Bentgrass 55, 127, 196,396

Berg's panicgrass 221

Bermuda grass 60, 127, 396, 419

Berseem clover 77, 142, 251, 400

Berteroa 376, 418

Beta 84, 107, 376

Betony 396, 423

Bicolor lespedeza 244, 406

Big bluegrass 226, 396

Big bluestem 127, 203, 397

Big-flowered clover 250, 253

Bigflower gilia 404, 418

Bigleaf sumpweed 413, 420

Big mouse-ear chickweed 399, 418

Bigseed falseflax 403, 418

Bigseed goosefoot 404, 418

Bigseed ladysthumb 406, 421

Big trefoil 75, 143, 245

Bindweed 258, 396

Bird rape.. 83, 119, 396

Bird vetch 256, 257, 415

Birdsfoot trefoil 75, 143, 245, 414

Bitter wintercress 418

Blackberry 396, 422

Black bindweed 396, 421

Black-eyed-susan 396, 422

Black henbane 405, 420

Black horehound 396, 418

Black medic 77, 143, 246, 407

Black mustard 83, 119, 235, 408

Black nightshade 408, 422

Blackseed plantain 410, 421

Bladder campion 232, 398

Bladder ketmia 396

Blond plantain 410, 421

Blotters 87

Blowers for cleaning dividers 12

Blowers, seed 15, 46

Blowwives 396, 417

Blue-bur 396

Blue cockle 396

Bluecurls 396, 423

Blue devil 396

Blue-eyed grass 396, 422

Blue grama 127, 209, 404

Bluegrass 67, 127, 224, 396

Blue lettuce 406, 420

Blue lupine 143, 245, 407

Blue panic grass 65, 128, 221, 409

Blue sailors 397

Bluestem 57, 127, 202, 397, 417

Bluets 397,420

Blue thistle 397

Blue vervain 414, 423

Blueweed 397, 419, 420

Blunt spikerush 412, 419

Boerhaavia 376, 418

Boer lovegrass 216, 407

Boerner divider 5, 8

Page

Boisduvalia 376, 418

Boisduvalia 397, 418

Botanical and common names__ 417-423

Botanical names 373-394

Bouteloua 57, 127, 209, 376

Boxes, soil and sand 21

Bracted plantain 410, 421

Bractless Mentzelia 407,421

Branching plantain 410, 421

Brassica 83, 119, 234, 376

Branneria 377, 418

Bristlegrass 228, 397

Bristlestem hempnettle 405, 419

Bristly dogtail 213, 402

Bristly ox tongue 409, 421

Broad bean 79, 142, 294, 397

Broadleaf plantain 410, 421

Broad-leaved carpet grass 208, 399

Broad-leaved dock 402, 422

Broccoli 83, 119, 397

Brodiaea 377, 418

Brodiaea 397, 418

Broken and cracked seeds 48

Brome 59-60, 127, 210, 397

Bromegrass 209, 397

Bromus 59, 127,209,377

Broomcorn___ 70, 127, 230, 397

Broomcorn millet 222, 397

Broomsedge 203, 397

Brown-r3uvel distillation method 185

Brown m ustard 234, 408

Brownscale knapweed 406, 418

Brownseed paspalum 222, 409

Browntop millet 65, 127, 221, 397

Browntop panicum 221, 409

Brussels sprouts 83, 119, 397

Buchloë 67, 127,208,377

Bu ckhorn 397

Buckhorn plantain 410, 421

Bu ckhorn seeds, shriveled 51

Buckwheat 81, 167,398

Buffalo-bur 398, 422

Buffalo clover 251, 252

Bufí'alo grass 67, 127, 208, 398

Bugle_._ 398

Bugleweed 398, 420

BuR-seed 398

Bulblets, wild onion and wild

garlic 52

Bulbous bluegrass 67, 127, 227, 396

Bulbous buttercup 398, 421

Bullnettle 398

Bull paspalum 222, 409

Bull thistle 413, 418

Bulrush 398, 422

Bunium 377, 418

Bupleurum 377, 418

Bur bristlegrass 228, 397

Bur-clover 77, 142, 246, 398

Burdock 398, 417

Burnet 398, 422

Burnweed 398, 419

Bur-ragweed 398

Bursa 377

Bur-sage 398,419

Bushy Mentzelia 407,421
INDEX 427

Page

Butter-and-eggs 398, 420

Buttercup 398, 421

Butterflyweed 398, 417

Butterprint 398

Buttonclover 246, 247, 398

Buttonweed 398,419

Cabbage. 83, 119, 234, 294, 398

Calculating test results 191-193

Caley pea 398

California brome 210, 397

California bur-clover 246, 398

California-poppv 398, 419

Caltrop 398

Caltrops 398

Camelina 377, 418

Camelthorn 238,398

Camomile 398

Campe 377

Campion 232, 398

Canada bluegrass 67, 127, 225, 396

Canada thistle 413,418

Canada wild-rye 55, 128, 215, 416

Canary grass 60, 127, 223, 398

Canby bluegrass â96

Cannabinaceae (hemp family):

dormancy treatments 167

kind of seed 167

seedling interpretation 169

su btrata for tests 168

Cannabis 84, 167, 377, 418

Cantaloup 82, 124, 399

Caperonia 378, 418

Capsella 237, 378

Capsicum^ 80, 167, 378

Caraway-- 399, 418

Cardaría 235, 378

Cardoon 84, 113, 399

Carduus 378, 418

Carex 378, 418

Carnation pests and injuries 294

Carolina canary grass 224, 398

Carolina clover --_ 250,252

Carolina cranesbill 401, 419

Carolina foxtail 202, 404

Carolina geranium 399

Carolina liorsenettle 399, 405

Carpet grass 58, 127, 208, 399

Carrot 80, 167, 294, 399, 419

Carthamus.. 378, 418

Carum 378, 418

Caryophyllaceae pests and inj uries 294

Cassia 239,378

Catch fly 232-233,399

Catchweed 399

Catnip 399, 421

Catnip savory 411, 422

Cats-ear 399, 420

Cattail millet 399

Caucalis 378

Cauliflower 83, 119, 399

Celeriac 80, 167, 399

Celery 80, 167,294,399

Celery-mustard 235

Cellulose paper, substratum 91

Cenchrus^ ,, 211, 378

Page

Centaurea 378,418

Centipede grass .. _ _ _ 399, 419

Ceniromadia 378, 418

Cephalaria 378, 418

Cephalaria 399, 418

Cerastiuni 378, 418

Cereals 126, 294

Chaerophyllum 378, 418

Chamomile 399, 417

Chamomilla 378

Chard, Swiss 399

Charlock 235,399

Cheat 399

Checking for accuracy 47

Cheesemallow 399, 422

Cheeses 399

Cheirinia 378

Chenoi:)odiaceae (goosefoot family):

dormancy tratments 107

kinds of seed 107

seedling interpretation 109

substrata for tests 108

Chenopodium 378, 418

Chervil

Chess

Chewings fescue

Chickpea

399,418

399

61, 127,217

73, 142, 239, 399

Chickpea milkvetch 239, 407

Chickweed 399,418

Chicory 84, 113, 399, 418

Chilean tarweed 413, 420

China aster pests and injuries.-- 294

Ch inese cabbage 235

Chinese lespedeza 74, 143, 243

Chinese milkvetch 239, 407

Chloris 66, 128, 211, 378

Chloris 399

Chondrilla 379, 418

Chorispora 236, 379

Chufa 399

Chrysanthe7nu7n 379, 418

Cicrr 73, 142, 239, 379

Cichorium 8,4, 113, 379, 418

Cicuta : 379,418

Cinquefoil 399, 421

Cirsium 379, 418

Citron 82, 124, 400

Citrullus 82, 124, 379

Classification of seedlings, guides. 96-97

Cleavers 400,419

Climbing milkweed - _ 407, 420

Clinopodium 379

Clover 77, 142, 238, 250, 295, 400

Club-awn 212,400

Cluster clover 77, 142, 250, 252

Clustered blue morning-glory 258

Clustered dock 402, 422

Cluster tarweed 413, 420

Coast blite 400

Coast dandelion 400

Coast fiddleneck 403, 417

Coated or pelleted seed 52, 105

Cockle---- 400

Cocksfoot grass 401

Coco grass 401

Coffee bean 401

Cogwheel clover -,- 246, 401
428 INDEX

Pag^e

Cold test 105

CoUards 83, 119, 401

Collomia 379, 418

Colonial bentgrass 55, 127, 196, 396

Commelina 379, 418

Common chickweed 399, 423

Common dayflower 402, 418

Common fumitory 404, 419

Common goatsrue 404, 419

Common groundsel 404, 422

Common lespedeza. __ 74, 143, 243, 406

Common milkweed 407, 417

Common millet 228, 229, 407

Common morning-glory 259, 408

Common mullein 408, 423, 407

Common oat 205, 207, 408

Common purslane 410, 421

Common ragweed 410,417

Common smartweed 412, 421

Common sowthistle 412, 422

Common Sudan grass 229, 413

Common sunflower 413, 420

Common tansy 413, 423

Common vetch 79, 143, 255, 415

Compositae (composite or sunflower family):

dormancy treatments 113

kinds of seed 113

seedling interpretation 114

substrata for tests 113

Cone-flower 401, 418

Conical catchfly 233, 399

Conium 379,418

Conringia 236,379

Containers, seed 14, 43

Convolvulus 258, 379

Corispermum 379, 418

Corn 62, 126, 295, 401

Cornbind 401

Corn-chamomile 401, 417

Corncockle 401, 417

Corn, field 401

Cornflower- 401

Cornsalad 80, 167, 401, 423

Corn speedwell 412, 423

Corn spurry__ 413,422

Coronilla 239, 379

Coronilla 401

Coronopus 236, 379

Corynephorus 212, 379

Cotton 81, 164, 295, 401

Cotton, substratum 90

Couch grass 401

Counters, seed 22

Counting the seeds 93

Cowcockle 401, 422

Cowherb 401

Cowpea 73, 143, 257, 401

Cow wheat 401,421

Crabgrass 401,419

Cracked and broken seeds 48

Cranesbill 401,419

Creeping bentgrass. __ 55, 127, 197, 396

Creeping buttercup 398, 422

Creeping crownvetch 240

Creeping Jennie 401

Creeping yellowcress 237, 416

Page

Crépis 379,418

Cress (crops) 83,119,401

Cress (weeds) 235,237

Crested dogtail 60, 127, 213, 402

Crimson clover 77, 142, 250, 254

Crinkled hairgrass 213, 405

Crooked clover 251, 252

Crop and weed seed illustrations_ 262

Crop judging 181

Crop seed interpretation 47

Crotalaria 74, 143, 240, 379

Crotalaria 74, 143, 240, 401

Crotón 379,401

Crowfoot plantai n 410,421

Crownvetch 239-240, 401

Cruciferae (mustard family) :

dormáncy treatments 119

kinds of seed 119

seedling interpretation 120

substrata for tests 120

Cruciferae pests 294

Crucifers and legumes devoid of

seed coats 49, 51

Cucumber 82, 124, 401

Çucumis 82, 124,379

Cucúrbita 82, 124, 379, 380

Cucurbitaceae (cucurbit family) :

dormancy treatments 124

kinds of seed 124

seedling interpretation 125

substrata for tests 125

Cultivated oats 205

Cupgrass 401, 419

Curlybloom 401

Curlycup gumweed 405, 420

Curly dock 402, 422

Curly thistle 413, 418

Cuscuta 259,260,380

Cusick bluegrass 226, 396

Cutleaf cranesbill 401, 419

Cutleaf evening-primrose 403, 421

Cutleaf germander 404, 423

Cutleaf nightshade 408, 422

Cyamopsis 240, 380

Cycloloma 380,419

Cylinder immortelle 405, 423

Cynara 84, 113, 380

Cynodon 60, 127, 380, 419

Cynosurus 60, 127, 212, 380

Cyperus 380, 419

Dactylis 60, 128, 213, 380

Daisy 401, 418

Daisy fleabane 419

Dallis grass 58, 127, 222, 401

Dandelion 84, 113,402,423

Danthonia 380

Darnel 220, 402

Dates, germination count 96

Datura 380,419

Daubentonia 240,380

Daucus 80, 167, 380, 419

Dayflower 402, 418

Dead nettle 402

Deathweed 402

Deervetch 245,402

Delphinium 380, 419
INDEX 429

Page

Dense-flowered Boisduvalia 397, 418

Deptfordpink______ 402,419

Deschampsia 213, 380

Desert purslane 402

Desert saltgrass 214, 411

Desks and tables 42

Desmodium 74, 142, 241, 380

Development of seeds 263, 265, 269

Devil's paintbrush 402

Dianthus 380, 419

Diaplianoscope 14

Dichondra 380, 419

Digestion 273

Digitaria 380, 419

Diodia 380, 419

Dipsacus 380, 419

Diseases identifiable during germination 287

Diseases identifiable prior to germination 286

Dissection of seed 50

Distichlis. 214, 380

Divider(s):

Boerner 5, 8

Garnet 8, 10

Hay-Bates 8, 11

Kny-Scheerer 7, 9

Ottawa 9,11

seed 43-44

soil 5, 7

Dock 402,422

Dodder 50-51, 259-261, 402

Dogbane 402, 417

Dogfennel 402, 417

Dogtail 60,212-213,402

Dondia 380

Dormancy, methods of overcoming 101

Dormancy treatments:

Aizoaceae 107

Chenopodiaceae 107

Compositae 113

Cruciferae 119

Cucurbitaceae 124

Gramineae 128

Leguminosae 143

Liliaceae 160

Linaceae 162

Malvaceae 164

Polygonaceae 167

Solanaceae 167

Umbelliferae 167

Dormant and dead seeds 100

Dormant embryos 280

Dovefoot cranesbill 401, 419

Downingia 380

Downy "chess 210, 399

Dracocephalum 380

Dragonhead 402, 421

Drooping-flowered clover 251, 252

Dropseed 66, 127,231,402

Early wintercress 416, 418

Earth nut 402, 418

Echinacea 381

Echinochloa 65, 127, 214, 381, 402

Echium 381, 419

Eggplant 80,

Egyptian clover

Electric moisture meters

Eleocharis z_

Eleusine

Elliott bentgrass

Elymus 55,128,

Embryo

Embryo, rudimentary

Emmer

Empty fruits

Endive 84,

Endosperm

English catchfly

Eragrostis 66, 127,

Erechtites

Erect hedgeparsley

Eremocarpus

Eremochloa

Erigeron

Eriochloa

Eriocoma

Erodium 82, 167,

Eruca

Erysimum

Erysimum

Eschscholtzia

Euphorbia

Euphrasia

European heliotrope

European stickseed

Evening-primrose 402,

Examination of seed

Eyebright

Page

167, 402

- 251

186

381,419

381, 419

198,396

214, 381

265, 269

50.280

_ ' 62

_ 48,51

113, 402

266, 269

233, 399

215,381

381, 419

405, 423

381, 419

381, 419

381,419

381, 419

_ 381

381, 419

236, 381

381,419

402, 419

382, 419

382, 419

382, 419

420

413, 420

403, 421

50, 338

403, 419

Fagopyrum. 81, 167, 382

Fairway crested wheatgrass 55, 127

Falcaría 382, 419

Falcatula 382

Fall-dandelion 403, 420

Fall panicum 221

Fall witchgrass 219, 403

False-camomile 403, 421

Falseflax 403, 418

False-mallow 403, 422

Fanweed 403

Fat-hen ¿03, 417

Fatuoids and wild oats 206

Fava bean pests 294

Feather fingergrass 212

Fennelñower 403, 421

Fenugreek 254, 403

Fescue 61, 127, 217-218, 403

Feduca 61, 127, 216, 382

Feterita 230, 403

Fetticus 167, 403

Fiddleleaf dock 402, 422

Fiddleneck 403, 417

Field bean__ 73, 142, 395

Field beet 396

Field betony 396, 423

Field bindweed 396

Field camomile 403

Fieldcress 237, 403

Field gromwell 404, 420

Field houstonia 403

Field larkspur 406, 419
430 INDEX

Page

Field madder 403, 422

Field mint 408, 421

Field mustard 236

Field paspalum 222, 409

Field pea 73, 143,409

Field peppergrass 410

Field sandbur 211, 411

Field scabiosa 412, 422

Field soybean 143

Field speedwell 412, 423

Field tests 179

Field woodrush 416, 420

Figwort 403,422

Filing samples 40

Filter paper 90

Fimbristyhs 382, 419

Fine hairgrass 201,405

Fine-leaved fescues 216-217

Fingergrass 211-212,403

Fireweed 403

Fivefinger 403

Five-hook bassia 395, 418

Flannel mullein 403

Flat pea 243,403

Flatweed 403,422

Flax 81, 162, 403, 420

Flax pests and injuries 295

Fleabane 403,419

Flexuous milkvetch 239, 407

Florets, grass, with immature

caryopses 51

Florida beggarweed 241, 403

Florida paspalum 222, 409

Florida speckled lupine 246

Florida velvetbean 249, 403

Flower-of-an-hour _ 403, 420

Flowering spurge 413, 419

Fluorescence test on ryegrass_ _ 103, 339

Fluorescent-light grids 33

Fog-fruit, spatulate 412, 420

Fool's parsley 403,417

Forceps 13, 21

Forget-me-not 403, 421

Forked bluecurls 396, 423

Forked catchfly 233, 399

Four-o'clock, wild 403

Fourseed vetch__ 256, 257

Fowl bluegrass 227, 396

Fowl mannagrass 407, 420

Foxtail ---- 66, 127, 202, 404

Foxtail barley 219, 395

Foxtail chess 210, 399

Foxtail fescue -- 217

Foxtail millet 65, 127, 229, 407

Franseria 382, 419

French weed 404

Fumaria 382, 419

Fumitorv 404, 419

Fungi 99

Gaertneria 404

Galega 241, 382, 419

Galega 241,404

Galeopsis 382, 419

Galinsoga 382, 419

Galinsoga 404,419

Galiumi . 382, 419

Page

Gamet divider 8, 10

Garbanzo 239

Garden bean 73, 142, 395

Garden beet 396

Garden fennelflower 403, 421

Garden pea 73, 143, 409

Garden sorrel 412, 422

Garlic and onion, wild, bulblets_ 52

Garlic, wild 404,417

Gastridium 382, 419

Gattinger's witchgrass 221, 416

Gaura 382,419

Gaura 404,419

Geraniaceae (geranium family) :

dormancy treatments 167

kind of seed 167

seedHng interpretation _ ._ 169

subtrat a for tests 168

Geranium 382,419

Geranium family 167

German madwort 407,417

German millet. 228,229,407

German velvetgrass 414,420

Germander 404, 423

Germination determination 86-106

Germination procedures for specific groups 107-171

Germination testing equipment:

beet seed washer . 35

ñuorescent-light grids 33

forceps 21

germination trays_^ 30

germinators 25

glassware 21

magnifiers and microscope 21

sample pans. 21

seed counters 22

soil and sand—

boxes 21

sterilizers 22

sprinkling devices 22

thermometers 25

ultraviolet lamp 32

Germination records . _ _ 192, 193

Germination trays 30

Germinators 25

Geum 382, 419

Giant bristlegrass 228, 397

Giant foxtaiL 229,404

Giant ragweed 410, 417

Gilia 383, 419

Gilia 404,418,419

Glassware 21

Glaucin m 383, 420

Globe gilia 404,419

Globemallow 404, 423

Glossary of terms 319-327

Glumes, effect on germination--... 277

Glyceria 383,420

Glyrine 73, 143, 241, 383

Goats-beard 404

Goatsrue 404,419

Goatweed 404

Godetia 383,420

Godetia 404,420

Golden dock 402, 422

Goldenweed 404,417
INDEX 431

Page

Goldmine millet 229

Gonolobus 383, 420

Goosefoot 404, 418

Goosegrass 404, 419

Gossypium 81, 164,383

Grain sorghum 127

Grama 57, 127, 209, 404

Gramineae (grass family) :

dormancy treatments 128

kinds of seed 128

seedling interpretation 131

substrata for tests 130

G rape-hyacinth 404, 421

G rass florets, immature 51

Grass pests and injuries 295

Grass seeds, damaged and immature 50, 51

Great burdock 398,417

Greater ammi 395, 417

Green foxtail 228, 404

Greenhouse tests 180

Green needlegrass 408, 423

Greenthread 404, 423

Grindelia 383, 420

Grisebach bristlegrass 228, 397

Gromwell 404, 420

Ground bugle 398, 417

Groundcherry 404, 421

Groundnut _I 404

Groundnut pea 243, 404

Groundsel 404, 405, 422

Grove woodrush 416, 420

Guar 240, 405

Guinea grass 65, 127, 221, 405

Gumweed 405, 420

Hackelochloa

Hair fescue 127,

Hairgrass 201,

Hairy buttercup

Hairy chess

Hairy gaura

Hairy goldenweed

Hairy grama

Hairy hawksbeard

Hairy indigo

Hairy morning-glory

Hairy mustard

Hairy panicgrass

Hairyseed sedge

Hairy tickseed

Hairy vetch 79, 143, 255,

Halogeton

Halogeton

Halving method

Hand lens

Harding grass 60, 127, 223,

Hares-ear-mustard

Harvest brodiaea

Hastings lupine

Hawkbit

Hawksbeard

Hawkweed

Hawkweed, picris

Hay-Bates divider

Hay-field tarweed

Heal-all

383, 420

217, 403

213, 405

398, 422

211,399

404, 419

404, 417

209, 404

405, 418

242, 406

259, 408

408, 420

221

412,418

414, 418

257, 415

383, 420

405, 420

39

- 13,45

224, 405

236, 405

397, 418

246

405, 420

405, 418

405, 420

405, 421

_ 8,11

413, 420

405, 421

Page

Hedeoma 383, 420

Hedge bindweed 258, 405

Hedgemustard 405, 422

Hedgenettle 405

Hedgeparsley 405, 423

Hedysarum 241, 383

Hegari 230, 405

Helianthus 84, 113, 383, 420

Heliotrope 405, 420

Heliotropium 383, 420

Hemizonia 383, 420

Hemizonia 405

Hemp 84, 167,405,418

Hemp dogbane 402, 417

Hempnettle 405, 419

Henbane 405, 420

Henbit 405, 420

Henderson's cheesemallow 399, 422

Herbarium, seed 20

Herd's-grass 405

Hereditary characteristics of

seeds 263,271

Heterotheca 383, 420

Hibiscus 81, 164, 383, 420

Hieracium 383, 420

Highland bentgrass___ 55, 127, 196, 396

High mallow 407, 420

High temperatures 102

Hillman panicgrass 221

Hirschfeldia 383, 420

Hispid deervetch 245, 402

Hoary alyssum 395, 418

Hoary cress 235, 405

Hoary vervain 414, 423

Hoffmannseggia 241, 383

Holcus 66, 128, 383, 420

Hood canary grass 224, 398

Hookera 383

Hop clover 251, 252

Hordeum 62, 126, 218, 383

Horehound 405, 421

Horned-rush 405, 422

Hornpoppy 405

Horse bean 142, 405

Horsenettle 405, 422

Horse-purslane 405, 423

Horseweed 405, 419

Hosackia 383

Houstonia ._ 383, 420

How to draw the sample 37

Hungarian millet 229, 408

Hungarian vetch_ 79, 143, 255, 256, 415

Husk tomato 80, 167, 405

Hybrids, sorghum-Sudan 405

Hyme7iophysa ._ 383

Hyoscyamus 383, 420

Hypericurn 383, 420

Hypochaeris 383, 420

Hyssop loosestrife 405, 420

Iberian star-thistle 413, 418

Identification of seeds 194-261

Illustrations, crop and weed

seeds . 262

Immature and shriveled seeds 48

Immortelle 405, 423

Impermeable seed coats 278
432 INDEX

Page

Imported seed 3

India mustard 83, 119, 234, 408

Indian grass 57, 127, 405

Indian hemp 405

Indian ricegrass 65, 128, 411, 421

Indian tobacco 405, 420

Indigo.. 405, 406

Indigofera 242, 383

Indigo, hairy 242, 406

Inhibiting substances 281

Inland bluegrass 226, 396

Insect-damaged seed 49

Integuments (seed coats) and

ovary wall (pericarp) 268

Integuments or seed coats 269

Interpretation of crop seed, applicable rule 47

Interpretation of weed seed, applicable rule 49

Interstate commerce, seed 3

Illahee fescue 216, 217

Ipomoea 258, 259, 383, 384

Ironweed 406, 423

Italian cornsalad 401, 423

Italian rvegrass 103, 127, 220

Italian thistle 414, 418

Iva 384,420

Ivyleaf morning-glory 259, 408

Jacquemontia 258, 259, 384

Japanese chess 211, 399

Japanese lawngrass 65, 127, 231, 406

Japanese millet 65, 127, 214, 406

Jim Hill mustard 406

JiniGonweed 406, 419

Johnson grass 70, 127, 229, 230, 406

Jointvetch 238, 406

Juncoides 384

Juncus 384,420

Jungle rice 214,406

Kafir 230, 406

Kale 83, 119, 406

Kentucky bluegrass_ 127, 225, 227, 396

Kickxia 384,420

Kidneyvetch 238, 406

Kimpak 91

King devil weed 406

Klamath-weed 406

Knapweed 406, 418

Knautia 384

Knawel 406,422

Knotgrass 222,406

Knotroot bristlegrass 228, 397

Knotted clover 250

Knotted hedgeparseley 405, 423

Knotweed 406,421

Knotweed family 167

Kny-Scheerer divider 7, 9

Kobe lespedeza 74, 143, 243, 244

Kochia 384, 420

Koellia 384

Kohlrabi 83, 119, 406

Korean lespedeza. 74, 143, 243, 244, 406

Kudzu 74, 143,249,406

Kura clover 250,254

Kursk millet 229

Page

Kyllinga 384, 420

KyUinga 406, 420

Labeling of seed 3

Laboratories, seed-testing 4

Laboratory space and light 42

Lacegrass 216, 406

Lactuca 84, 113, 384, 420

Ladino clover 142, 250

Ladysthumb 406, 421

Lambsquarters 406, 418

Lamb-succory 406, 417

Lamium 384, 420

I^amp, ultraviolet 32

Lamps 20

Lance crotalaria 240, 401

Lanceleaf sage 411, 422

Lappa clover 77, 142, 250, 253

Lappula 384, 420

Lapsana 384, 420

Large crabgrass 401,419

I^arge-flowered brodi aea 397, 418

Large-headed plumeless thistle. _ 418

Large hop clover. 77, 142, 250, 252, 400

I^arge-seeded legumes 73

Larkspur 406, 419

Laihynis 143, 242, 384

Lavender grass 406

Law(s) :

Federal Seed Act 3

State seed 3

Truth-in-Labeling 3

Leafy spurge 413, 419

Leek 82, 160, 406

Legumes and crucifers devoid of

seed coats 49, 51

Legumes of limited use 74

Leguminosae (legume or pea

family) :

dormancy treatments 143

hard seeds 144

kinds of seed 142

seedling interpretation 146

substrata for tests 144

Lehman lovegrass 216, 407

Lens peppercress 235, 409

Leontodón 384, 420

Leonurus 384, 420

Lepidium 83, 119, 236, 384, 420

Leptoloma 219, 385

Lespedeza 74, 143, 243, 385

Lespedeza 74, 143, 243, 244, 406

Lettuce 84, 113,406,420

Light, effect on germination- 95, 102,276

Lilac sage 411,422

Iñliaceae (lily family) :

dormancy treatments 160

hard seeds 160

kinds of seed 160

seedling interpretation 160

substrata for tests 160

Lima bean 73, 142, 395

Linaceae (flax family) :

dormancy treatments 162

kind of seed 162

seedling interpretation 162

substrata for tests 162
INDEX 433

Page

Linaria 385, 420

Linum 81, 162,385,420

Lippia 385, 420

Lithospermum 385, 420

Little barley 219,395

Little bluestem 127, 203, 397

Little burnet 398, 422

Little canary grass 224, 398

Little flower mealybean 407

Little mallow 407, 420

Little-seed falseñax 403, 418

Little starwort 413, 423

Lizard-tail grass 407, 420

Lobelia.-.-. 385,420

Loco - 238

Lolium 64, 127,219,385

Longstalk cranesbill 401, 419

Long-tongue mutton grass 226, 408

Loosestrife, hyssop 405, 420

Lotus - 75, 143, 245, 385

Louisiana cupgrass 401,419

Lovegrass 66, 127,215,407

Love-in-a-mist 407, 421

Lovevine 407

Low vetchling 243, 415

Lucerne 246

Ludwigia 385, 420

Lupine 73, 143, 245, 407

Lupinus 73, 143, 245, 385

Luzula 385, 386, 420

Lychnis 232, 386

Lycopersicon 80, 167, 386

Lycopus 386, 420

Lythrum 386, 420

Madia 386,420

Madwort 407, 417

Magnifiers 13, 21

Mallow 407, 420, 422

Malta star-thistle 413,418

Malva 386, 420

Malvaceae (mallow family) :

dormancy treatments 164

hard seeds 164

kinds of seed 164

seedling interpretation 165

substrata for tests 164

Malvasirum 386, 421

Mangel 84, 107,407

Manilagrass 65, 127,231,407

Mannagrass 407, 420

Mapleleaf goosefoot 404, 418

Marijuana 407

Marruhium 386, 421

Marsh betony 396, 423

Marsh elder 407

Mascarene grass 231, 407

Matricariu 386, 421

Mayweed 407

Meadow anemone 395,417

Meadow barley 219,395

Meadow fescue 127, 218, 403

Meadow foxtail 66, 128, 202, 407

Meadowrue 407, 423

Meadow salsify ^ 411, 423

Meadow softgrass 407

Mechanical dividers, use of 39

Page

Medicaao 77, 142, 143, 246, 386

Medic, black 77, 143, 246, 407

Meihomia 386

Melampyrum 386, 421

Melilotus 75, 143, 247, 386

Melinis 66, 128, 386, 421

Melochia 386, 421

Mentha 386,421

Mentzelia 386, 421

Mentzelia__. 407,421

Menzies larkspur 406, 419

Merion bluegrass 226, 396

Merker grass 407

Methods of examination 50

Mexican milkweed 407, 417

Mica 92

Microscope 13, 21

Mignonette 407

Milkvetch 238-239, 407

Milkweed 407, 417

Millet (crops) 65, 127, 221, 227, 407

Millet (weeds) 221, 227, 228

Milo 230, 408

Mint 408, 421

Mirabilis 386, 421

Moisture and aeration 94

Moisture effects on seed 275, 282

Moisture tests 183-186

Molasses grass 66, 128, 408, 421

Moldávica 386,421

Molinia 386, 421

Monantha vetch__ 79, 143, 255, 257, 415

Moorgrass 408, 421

Morning-glory 408, 420

Morning-glorv family 258-259

Motherwort_*'_ 408,420

Mountain brome 127, 210,397

Mountain-mint 408, 421

Mouse-ear 408

Mullein 403, 408, 423

Mung bean 73, 142, 248, 395

Muscari 386, 421

Musk mallow 407, 420

Muskmelon 82, 124, 399, 408

Mustard_ 83, 119, 233, 408, 420

Mutton grass 226, 408

Myosotis 386,421

Naked ragweed seed

Napa thistle

Napier grass 128,

Narrowleaf goosefoot

Narrowleaf vetch_ 79, 143, 255-

Narrow-leaved carpet grass

Nassella

Navarretia

Navarretia

Neckweed

Needlegrass

Needle-leaved Navarretia

Nepeta

Neslia

Nettle

Nettleleaf goosefoot

Nevada bluegrass 67, 127,

New York ironweed

New Zealand spinach 84,

51

- 408

223, 408

404, 418

257,415

208, 399

220, 386

386, 421

408, 421

_ 408

408

408, 421

387, 421

387, 421

408, 423

404, 418

226, 396

406, 423

107, 413
434 INDEX

Page

Nicotiana 334,387

Nigella 387, 421

Night-flowering catchfly 233,399

Nightshade 408, 422

Nightshade family 80, 167

Nipplewort 408, 420

Nitgrass 408, 419

Nitrate solutions 277

Nodding spurge 413, 419

Nomograph, for fluorescence

tests 339, 340

Narthern jointvetch 238, 406

Northern oat 207, 408

Noxious-weed seed:

examinations 172-174, 338

State requirements 3

tolerances 189,362-363

Number ofseedsin germination test_ 92

Numbers of seeds per gram 330-336

Nutgrass 408, 419

NuttaU milkvetch 239, 407

Oat 57, 126, 205-208, 408

Oatgrass 66, 128, 204, 213, 409

Oenothera 387, 421

Oflicial rules for testing seeds- 328-368

Okra 81, 164, 409

Oldfield cinquefoil 399, 421

Onion 82, 160,409

Onion and garlic, wild, bulblets. _ 52

Onohrychis 143, 248, 387

Ononis 248, 387

Ononis 248, 409

Opium poppy 410, 421

Orach 409,417

Orange hawkweed 405, 420

Orchard grass 60, 128, 213, 409

Origin determination 175-177

Orniiho'pus 248, 387

Oryza 62, 126, 387, 421

Oryzopsis 65, 128,387,421

Ottawa divider 9, 11

Ovary wall 268-269

Overcoming dormancy 101

Oxalis ' 387, 421

Oxalis 409, 421

Ox-eye daisy 409, 418

Oxtongue 409,421

Oxybaphus 387

Oxygen 276

Pakchoi 83, 119, 235, 409

Pale alyssum 395, 417

Pale ladysthumb 406, 421

Paleseed plantain 410, 421

Panicgrass 65, 128, 220-222, 409

Panicularia 387

Panicum 65, 127, 128, 220, 387

Panicum 220-222, 409

Pans, sample 14, 21

Pansy 409, 423

Papaver 387, 421

Paper toweling 88

Para grass 221, 409

Parentucellia 387

Parsley 80, 167, 409, 421

Parsley pests and injuries 295

Page

Parsnip 80, 167, 409

Partial list of pests and injury

conditions 293-296

Paspalum 58, 127, 222, 387, 388

Paspalum 222-223, 409

Pastifiaca 80, 167, 388

Pathological considerations 284-296

Path rush 411,420

Pea 73, 143, 243, 409

Pea, Austrian Winter 249

Pea pests and injuries 295

Pea, rough 74, 243, 411

Pea, sensitive 239, 412

Pea, Tangier 243, 413

Peach-leaved dock 402, 422

Peanut 73, 143, 409

Peanut pests and injuries 295

Pearl millet 62, 127, 223, 409

Peatmoss 91

Peaweed 409

Pellett clover 250

Pelleted or coated seed 52, 105

Pennisetum 62, 128, 223, 388

Pennisetum 409

Pennycress 409, 423

Pennyroyal 409, 420

Pepper 80, 167, 409

Peppercress 235, 409

Peppergrass 409, 410, 420

Pepper pests and injuries 296

Perennial ground cherry 404, 421

Perennial mustard 237, 410

Perennial peppercress 409

Perennial ragweed 417

Perennial ryegrass 64, 127, 220, 411

Perennial sowthistle 412, 422

Perianth 263,324

Pericarp 268-269

Persian clover 142, 250, 253

Persian ryegrass 220, 411

Pests and injury conditions:

bean {Phaseolus spp.)-- 287, 294

beet 290,294

broad or fava bean 294

cabbage and other Cruciferae 289,294

carnation and other Caryophyllaceae 294

carrot 294

celery 291,294

cereal or small grains. _ 288, 294

China aster 294

clover and alfalfa 291, 295

corn (maize) 288,295

cotton 290,295

flax 290,295

grass 295

parsley 295

pea 287,295

peanut 295

pepper and tomato 296

rice 291,296

soybeans 296

tree 296

vetch 296

Petri-dish tests 87, 92
INDEX 435

Page

PetroseUnum 80, 167, 388, 421

Pe-tsai___ 83, 119,235,410

Phacelia 388

Phalaris 60, 127, 223, 388

Phaseolus 73, 142, 248, 388

Phleum 66, 128,388,421

Physalis 80, 167, 388, 421

Physiologically unripe seed 279

Physiology of seeds 273-283

Picris 388, 421

Pimpernel 410, 417

Pimpinella 388,421

Pimpinella 410, 421

Pinole clover 251, 254

Pinpoint clover 251, 254

Piptochaetium 388

Pisum 73, 143,249,388

Pitseed goosefoot 404, 418

Plagiohothrys 388, 421

Plains bliiegrass 227, 397

Plains bristlegrass 397

Plains cheesemallow 399, 422

Plantago 388, 389,421

Plantain^ 410,421

Plant names 395-416

Plumeless thistle 410,418

Poa 67, 127, 224, 389

Poison hemlock 410, 418

Poison ryegrass - 410

Polygonaceae (knotweed family) :

dormancy treatments 167

kinds of seed 167

seedling interpretation 169

substrata for tests 168

Polygonum - 389,421

Polypogon 389, 421

Ponyfoot 410, 419

Popcorn 62, 126, 410

Popcorn flower 410, 421

Poppy 410, 421

Portulaca 389, 421

Potassium nitrate and soil 102

Potentilla 389, 421

Poverty clover 251, 252

Poverty grass 204,410

Poverty oatgrass 213, 409

Poverty sumpweed 413, 420

Poverty three-awn 410,414

Povertyweed 410

Prairie burnet 398, 422

Prairie coneñower 410, 422

Prairie peppergrass 410, 420

Prairie-rocket 410

Prairie trefoil__ 245,410

Predrying 103

Prickly lettuce 406, 420

Prickly mallow 407,422

Prionopsis 389

Proso 65, 127, 222, 410

Prunella 389, 421

Psyllium plantain 410, 421

Pueraria 143, 249, 389

Puff dropseed 231, 402

Pumpkin 82, 124, 410

Puncturevine 410, 423

Purity determination 42-53

Page

Purity procedures for speciñc

groups 54-85

Purity testing equipment:

diaphanoscope

forceps and spatula

lamps

magnifiersmicroscope

scales and balances

sample pans

seed blowers

seed containers

seed herbarium

14

13

20

13

13

13

14

15

14

20

14

12

sieves

workboard

Purple bluets 397,420

Purple coneñower 401, 418

Purple-flowered groundcherry_ 404, 421 *

Purple star-thistle 413, 418

Purpletop 410, 423

Purple vetch 79, 143, 255, 257, 415

Pursh seepweed 410

Purslane 410,421

Purslane speedwell 412, 423

Pycnanthemum 389, 421

Quackgrass 410

Queen Anne's-lace 410

Queensland beardgrass 202, 396

Quincula 389

Rabbitfoot clover 251, 253, 400

Rabbitfoot grass 410, 421

Radish 83, 119, 410, 422

Ragi 410

Ragweed 410, 417

Ragweed seed, naked 51

Ragwort 411, 422

Raimannia 390

Random cups method 39

Ranier fescue 217

Ranunculus 390, 421, 422

Rape 83, 119, 234, 411

Raphanus 83, 119, 390, 422

Rapistrum -_ 390, 422

RatiUda 390, 422

Rattail fescue 217, 403

Rattlebox 240,411

Record cards, sample 369, 370

Record, sampling 38

Records and reports 191-193

Red campion 232,398

Red clover 77, 142, 250, 253, 400

Redfescue 127,403

Red goosefoot 404, 418

Red hempnettle 405, 419

Red oat 207,408

Red orach 409,417

Redroot amaranth 395, 417

Redscale 411

Red-seeded dandehon 402, 423

Redseed plantain 410, 421

Redtop 55, 128, 197,411

Reducing the sample 39

Reed canary grass 60, 127, 223, 399

Ree wheatgrass 199, 201, 415

Rescue grass 59, 128, 210, 411

Reseda 390, 422
436 INDEX

Page

Respiration 274

Rheum 81, 167, 390

Rhodes grass 66, 128, 212,411

Rhubarb 81, 167, 411

Rhynchospora 390, 422

Ribbed paspalum 223, 409

Ribgrass 411

Rice 62, 126, 411, 421

Ricegrass 65, 128,411,421

Rice pests and injuries 296

Ringwing 411, 419

Ripgut grass 211, 411

Riverbank wild-rye 215, 416

Roemeria 390, 422

Roemeria poppy 411, 422

Rorippa 83, 119, 237, 390

Rosa 390, 422

Rose 411,422

Rose clover 250, 254, 400

Rouhieva 390, 422

Rough blistercress 411,419

Rough bluegrass 67, 127, 225, 397

Rough buttonweed 398, 419

Rough hawkbit 405, 420

Rough pea 74, 143,243,411

Rough pigweed 411, 417

Rough sumpweed 413,420

Roundleaf thoroughwax 414, 418

Roundleaf toadflax 414, 420

Ruhus 390, 422

Ruby milkvetch 239, 407

Rudbeckia 390,42.2

Rudimentary embryo 50, 280

Rules for testing seeds:

development 2

germination 341

history 2

in foreign countries 2

nature 2

official 328-368

purity 329

sampling 328

tolerances 356

Rumex 81, 167, 390, 422

Runner bean 73, 142, 395

Running mallow 407, 420

Rush 411, 420

Rushgrass 411

Rushpea 241,411

Russian pigweed 411, 418

Russian thistle. 411, 418, 422

Rutabaga 83, 119, 234, 411

Rye 62, 126, 411, 422

Ryegrass 64, 127, 220, 411

Ryegrass, fluorescence test 103

Safflower 411, 418

Sage 411,422

Sainfoin 74, 143, 248, 411

Salad-rocket 236, 411

Salsify 84, 113, 411

Salsola 390, 422

Saltbush 411

Saltgrass 214, 411

Salt heUotrope _ _ _ 405, 420

Salvia 390,422

Sample, drawing of 37

Page

Sample pans 14, 21

Samplers 5, 6

Samples awaiting test 40

Samples, filing 40

Samples, size 38

Sampling 37-39, 328-329

Sand and soil 89

Sand bluestem 57, 127, 203, 397

Sandberg bluegrass 227, 397

Sandbrier 411

Sandbur 211, 411

Sand dropseed 66, 127, 231, 402

Sand lovegrass 216, 407

Sand oat 208, 408

Sandvine 411

Sandwort 411, 417

Sanguisorba 390, 422

Sanitary conditions of equipment

and supplies 95

Saponaria 390, 422

Sarson 234

Satureja 390, 422

Savory 411, 422

Sawdust 92

Saxifrage pimpernella 410, 421

Scabiosa 390, 422

Scabiosa 411, 412, 422

Scabiosa star-thistle 413, 418

Scales and balances 13, 44

Scaleweed 412

Scarlet gaura 404, 419

Scarlet globemallow 404, 423

Scarlet pimpernel 410, 417

Scented gaura 404, 419

Schedonnardus 390, 422

Scirpus 390, 422

Scleranthus 390, 422

Sclerotia and nematode galls 49

Scorpion crownvetch 240,401

Scorpionweed 412, 417

Scratch dropseed 231, 402

Scrophularia 391, 422

Sea-blite 412,423

Sea-poppy 412, 420

Seashore saltgrass 214,411

Seaside clover 251, 253, 400

Sécale 62, 126, 391, 422

Sedge 412, 418

Seed blower 15, 46

Seedbox 412, 420

Seed-coat modification 103

Seed coats 268, 267-270

Seed containers 14, 43

Seed counters 22

Seed dividers 43

Seed herbarium 20

Seed identification 194-261

Seed in interstate commerce 3

Seed laboratories:

commercial 4

Federal 4

State 4

Seed morphology 263-272

Seed physiology 273-283

Seed sampling 37-41

Seed testing, primary objective- _ 1

Seed-testing rules 328-368
INDEX 437

Page

Seedling classification 96-97

Seedling interpretation (s) :

Aizoaceae 109

Chenopodiaceae 109

Compositae 114

Cruciferae 120

Cucurbitaceae 125

Gramineae _ _ 131

Leguminosae 146

Liliaceae 160

Linaceae 162

Malvaceae 165

Polygonaceae 169

Solanaceae 169

Umbelliferae 169

Seepweed 412

Selfheal 412

Senecio 391, 422

Sensitive pea 239, 412

Sericea lespedeza 74, 143, 243, 406

Serradella 248, 412

Sesame 412, 422

Sesamum 391, 422

Seshania 74, 143, 249, 391

Sesbania 74, 143, 249, 412

Setaria 65, 127, 227, 391

Shaftal clover 250

Sheep fescue 61, 127, 217, 403

Sheep sorrel 412, 422

Shepherds-purse 237

Sherardia 391, 422

Short-awn foxtail 202, 404

Showy crotalaria 240, 401

Showy vetch 256, 257, 415

Shriveled seeds of buckhorn 51

Siberian kale 234, 406

Siberian lespedeza_ 74, 143, 243, 244, 406

Siberian millet 229

Sicklepod 239, 412

Sickleweed 412, 419

Sida 391, 422

Sida 412

Sidalcea 391, 422

Sidalcea 412

Side-oats grama 57, 127, 209, 404

Sideritis.__„ 391, 422

Sidopsis 391, 422

Sieves 14

Silène 232, 391

Silky bluestem 203, 397

Silver hairgrass 201, 405

Silver-leaf nightshade 408, 422

Silversheath knotweed 406, 421

Singletary pea 412

Sisymbrium 237, 391, 422

Sisyrinchium 391, 422

Sixweeks fescue 217

Size of samples 38

Skeletonleaf bur-sage 398, 419

Skeletonweed 412, 418

Skunkweed 412, 421

Sleepy catchfly 233, 399

Slender chloris 212, 399

Slender crabgrass 401, 419

Slender foxtail 202, 404

Slenderleaf crotalaria 240, 401

Slender oat 207, 408

Page

Slender paspalum 222, 409

Slender plantain 410, 421

Slenderpod deervetch 245, 402

Slender spikerush 412, 419

Slender vetchling 243, 415

Slender wheatgrass 55, 127,415

Slimweed bur-sage 398, 419

Sloughgrass 208, 412

Small cranesbill 401, 419

Smallflower Erysimum 402, 419

Small-flowered buttercup 398, 422

Small-flowered morning-glory. 259, 408

Small-headed clover 251, 254, 400

Small hop clover 143, 250, 252, 400

Smartweed 412, 421

Smilo . 65, 128, 412, 421

Smooth brome 127, 210, 397

Smooth crabgrass 401, 419

Smooth hawksbeard 405, 418

Smooth-seeded wild bean 249, 395

Smooth vetch 255

Snowberry 412, 423

Snow-on-the-mountain 412, 419

Soft chess 211, 399

Soft grass 412

Soil and sand boxes 21

Soil and sand sterilizers 22

Soil divider 5, 7

Soja 391

Solanaceae (nightshade family) :

dormancy treatments 167

kinds of seed 167

seedling interpretation 169

substrata for tests 168

Solanum 80, 167, 391, 422

Sonchus 391, 392, 422

Sorghastrum 57, 127, 392

Sorghum 70, 127, 230, 392

Sorghum 70, 127, 229,412

Sorghum-Sudan hybrids 230, 412

Sorrel 81, 167, 412, 422

Source of seedsfor germination test_ 92

Sourclover 75, 143, 247, 400

Southern bur-clover 246, 400

Southern curled mustard 119

Southern oat 207, 408

Sowthistle 412, 422

Soybean 73, 143, 241, 412

Soybean pests and injuries 296

Spacing the seeds ^_ 93

Spatula 13

Spatulate fog-fruit 412, 420

Special tests 53

Specularia 392, 422

Speedwell 412, 423

Spelt . _ 62

Spergula _ 392, 422

Sphaeralcea 392, 423

Spiderling 412, 418

Spiderwort 412, 423

Spikebentgrass 198, 396

Spike redtop 412

Spikerush 412, 419

Spikeweed 412, 418

Spinacia 84, 107, 392

Spinach 84, 107, 412

Spinach mustard 83, 119, 235, 408
438 INDEX

Page

Spiny sowthistle ^ _ 412, 422

Sporoholus 66, 1^7, 231, 392

Spotted bur clover 77, l42, 246, 398

Spotted cats-ear 399, 420

Spotted knapweed 406, 418

Spotted spurge 413, 419

Spotted water-hemlock 415, 418

Spreading dogbone 402, 417

Spreading pigweed 413, 417

Spring savory 411, 422

Sprinkling devices 22

Spurge 413, 419

Spurry ._ 413, 422

Squash á2, 124,413

Stachys 392, 423

Standard crested wheatgrass 55,

127, 415

Star-thistle 413, 418

Starwort 413,423

Steeping in water 103

Sterilizers, soil and sand 22

Stellaria 392, 423

Stickseed 413, 420

Stinkgrass - 216, 413

Stinkweed 413

Stipa 392,423

Stizolohium 73, 142, 249, 392

St. Johnswort 413,420

Stinging nettle 408, 423

Stone cells .- 392,413

Strawberry clover. 77, 143, 250, 253, 400

Strawberryweed -_ 413, 421

Striate clover 250, 253, 400

Striate crotalaria 240, 401

Striate lespedeza 243, 244

Stricta Boisduvalia 418

Strophostyles 249, 392

Structure of seeds 263-271

Suaeda — 392, 423

Sub clover 143, 250, 254, 400

Substrata, germination:

Aizoaceae 108

Chenopodiaceae 108

Compositae 113

Cruciferae 120

Cucurbitaceae 125

Gramineae 130

Leguminosae 144

Liliaceae 160

Linaceae 162

Malvaceate 164

Polygonaceáe 168

Solanaceae 168

Umbelliferae 168

Substratum:

blotters -- 87

cotton --- 90

creped cellulose paper

wadding 91

filter paper 90

Kimpak 91

mica 92

paper toweling 88

peatmoss 91

Petri-dish test 92

sand and soil 89

sawdust-,--^^--- ^- 92

Suckling clover, __ 77, 143, 250,

Sudangrass 70,127,229,

Sugar beet 84,

Sulla

Summer cypress

Summer rape

Sumpweed

Sunflower 84, 113,

Sunn crotalaria

Sun spurge

Swainsonia

Sweetclover 75, 143,

Sweet corn 62,

Sweet sorghum

Sweet Sudan grass

Sweet vernalgrass 66, 128,

Swine-cress

Swiss chard 84,107,

Switchgrass 65,128,

Symphoricarpos

Tables and desks

Tall buttercup

Tall fescue 61,127,

Tall hedge mustard

Tall indigo

Tall lettuce

Tall oatgrass 66, 128,

Tanacetum

Tangier pea

Tansy

Tansy mustard

Tansy ragwort 411,

Taperleaf groundcherry

Taraxacum 84,113,

Tarweed

Tassel grape-hyacinth

Teasel

Teasel clover 251,

Teesdalia

Teff

Temperature effects on seed

Temperature, germination

101,

Test result calculations

Tests, field

Tests, special

Tetragonia 84,

Teucrium

Texas bluegrass 67, 127,

Texas blueweed

Texas millet

Thalictrum

Thelesperma

Thermometers

Thimble clover 251,

Thistle 413,

Thlaspi

Thorn-apple

Thoroughwax

Three-awn

Three-seeded mercury

Thymeleaf sandwort

Ticklegrass

Tickseed

Tievine

Tift Sudan grass_^_^^-^_^—

Page

252, 400

230, 413

107, 396

241,413

413, 420

234,411

413, 420

413, 420

240, 401

413,419

250, 392

247, 413

126, 401

127, 230

229, 413

204, 414

_ 413

399, 413

222, 413

392, 423

42

398, 421

218, 403

_ 413

._ 413

407, 420

205, 409

292, 423

243, 413

413, 423

237, 413

413, 422

404, 421

392, 423

413, 420

404, 421

413, 419

252, 400

392, 423

216,413

281

94,

102, 275

191-193

._ 179

53

107,392

392, 423

226, 397

397, 420

221, 413

392, 423

392, 423

25

254, 400

414,418

392, 423

414

414, 418

204, 414

414,417

411,417

198, 414

414, 418

._ 414

229, 413
INDEX 43g

Page

Timothy 66, 128, 414, 421

Timothy canary grass 224, 399

Tiny vetch 256, 257, 415

Tipton-weed 414

Toadflax 414,420

Tocalote 414

Tolerances 187-190, 356-368

Toluene distillation method 185

Tomato 80, 167, 414

Tomato pests and injuries 296

Tomcat clover _ 251, 253, 400

Toothed bur-clover 246

Toothed cornsalad 401, 423

Toothed spurge 413, 419

Toothpick plant 414, 417

Torilis 392, 393, 423

Towermustard 414, 417

Tradescantia 393, 423

Tragopogón 84, 113, 393, 423

Trays, germination 30

Treacle-mustard 414, 419

Tree pests and injuries 296

Trefoil 75, 143, 245, 414

Trianthema 393, 423

Trihulus 393, 423

Trichostema 393, 423

Tridens 393,423

Triers, seed 5, 6

Trifolium 77, 142, 250, 393

Trigonella 254, 393

Trigonella 254-255, 414

Trinius bluegrass 397

Triodia 393

Trisetum 393, 423

Trisetum 414, 423

Triticum 62, 126, 394, 423

Trompillo 414

Tualatin oatgrass 205

Tufted hairgrass 213, 405

Tumblegrass 414, 422

Tumblemustard 414, 422

Tumbling pigweed 414

Turkestan bluestem 202

Turkey mullein 414, 419

Turkistan thistle 414

Turnip 83, 119, 235, 414

Turnip rape 83, 119,235,414

Tussack grass 414

Ultraviolet lamp 32

Umbelliferae (carrot family) :

dormancy treatments 167

kinds of seed . 167

seedling interpretation 169

substrata for tests 168

Urtica 394, 423

Vaccaria^ 394

Vacuum-oven method 184

Valerianaceae (valerian family) :

dormancy treatments 167

kinds of seed- 167

seedling interpretation 169

subtrata for tests 168

Valerianella 80, 167, 394, 423

Variety identification 52

Variety testing 178-182

Vasey grass 58,128,

Vegetable mustard

Vegetable soybean

Veiny dock

Velvetbean 73, 142,

Velvet bentgrass- 55, 127, 197,

Velvet grass 66, 128,

Velvet-leaf

Venus's-looking-glass

Verhascum

Verbena

Vernalgrass

Veronica

Vervain

Vetch 79,143,

Vetch pests and injuries

Vetchling

Viability, determination

Vicia., 79,143,

Vigna 73,143,

Vinegar bluecurls

Vine-mesquite

Viola

Virginia buttonweed

Virginia spiderwort

Virginia wild-rye

Page

222, 414

83

143

402, 422

249, 414

198, 396

411,420

414

414, 422

394, 423

394, 423

203, 414

394, 423

414, 423

255, 415

- 296

242, 415

105

255, 394

257, 394

396, 423

222, 415

394, 423

398, 419

412, 423

215, 416

Wall barley 219

Wallflower 415

Wart-cress 236, 415

Water foxtail 202, 404

Water-hemlock 415, 418

Watermelon 82, 124, 415

Water-oven method 184

Wavyleaved gaura 404, 419

Wedgescale orach 409, 417

Weed and crop seed illustrations. 262

Weed seed, interpretation 49

Weed seeds devoid of seed coats__ 51

Weeping lovegrass 66, 127, 216, 407

Weights of working samples__ 330-336

Weingaertneria 394

Western bluestem 397, 415

Western dock 402, 422

Western snowberry 412, 423

Western stickseed 413, 420

Western wheatgrass 55, 127,415

Westernvolth ryegrass 219

Wheat 62, 126, 415, 423

Wheatgrass 55, 127, 198, 415

White bedstraw 396, 419

White blossom sweetclover_ 75, 400, 413

White clover 77, 143, 250, 253, 400

White cockle 232, 400, 415

White horehound 405, 415, 421

White horsenettle 405, 415

White-leaved povertyweed 416

White lupine 73, 143, 245, 246, 407

White mustard 83, 119, 234, 408

White-seeded yellow lupine 246

Whitestem mentzelia 407, 421

White sweetclover 247, 400

Whitetip clover 251, 253, 400

Whitetop 416

White vervain 414, 423

White Wonder millet 229, 407

Whorled milkweed 407, 417
440 INDEX

Page

Wild bean 395

Wild carrot 399, 419

Wild celery 399,417

Wild chervil 416, 417

Wild flax 416

Wild four-o^clock 416,421

Wild garlic 404,417

Wild madder 416

Wild oat 207,409

Wild onion and wild garlic bulblets 52

Wild pansy 409,423

Wild potato vine 416

Wild radish 410,422

Wild rose 422

Wild-rye 55, 128,214,416

Wild sunflower 420

Wild teasel 413,419

Willow-herb___ 416

Willow-leaved dock 402, 422

Wimmera ryegrass 103, 219, 411

Windgrass 204, 416

Windmill grass 212,416

Winged pigweed 416

Wingseed spurry 413, 422

Winter bentgrass 198, 396

Wintercress 416, 418

Winter rape 83, 119,234,411

Wiregrass 416

Witchgrass 219,416

Wolfberry 416

Wood bluegrass 67, 127, 226, 397

Woodland flax 403,420

Wood meadow grass^ 416

Woodrush 416,420

Wood sorrel 416

Woollypod vetch_ 79, 143, 255, 257, 415

Page

Workboard 12,42

Wormseed mustard 416

Woundwort 416

Xeranthemum 394, 423

Yardlong bean 396

Yarrow 416,417

Yellow beardgrass 203, 396

Yellow blossom sweetclover 75, 400

Yellow bluestem 202

Yellow chamomile 399, 417

Yellow clover 400

Yellowcress 237,416

Yellow false-mallow 403, 422

Yellow fieldcress 237, 403

Yellow foxtail 229,416

Yellow hop-clover 416

Yellow Indian grass 127, 405

Yellow lupine____ 73, 143, 245, 246, 407

Yellow melilot 248

Yellow nutgrass 408, 419

Yellow oxalis 409,421

Yellow pea 416

Yellow rocket 416

Yellow star-thistle 413, 418

Yellow sweetclover 247, 413

Yellow trefoil 416

Yellow trisetum 414, 423

Yellow vetch 255, 256, 415

Yellow vetchling 242, 415

Yorkshire fog 416

Zea 62,126,394

Zigzag clover 250, 254, 400

Zoysia 65, 127, 231, 394

Zoysia 231,416

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3 1 4 Idle

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I 7 18 I 9 1 io|

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10 MlLU-1

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2 3 4

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1 7 1 8 1 9| 1 io|

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10 M'ILUI-1

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1 2 1 3 1 4

CENTIMETERS 1

1 7 1 8 . 9| 1 10|

liillllli III! lili Uli Illi illi M M MM illi II il MM an mi mi mi mum

10 MlLLI-l

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2 3 4

CENTIW FTPRS^

7 8 9 10

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10 M'ILLI-I

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2 3 4

CENTir IFTF

6

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7 1 8 9 10

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2 1 3 4 5|

CENTIMETE RS«

7 s 9 10

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2 3 4 1 5

CENTIIVIFTE

6

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7 8 9 10

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10 M'ILLI-I

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2 3 4

CENTI^ IFTF

6

RS

7 8 9 10

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10 MILLI-l

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2 3 1 4 1 5

CENTm IFTE RS^

7 8 .9 10

illlilill INI im im mi MM illi illi llll llll llll MM Ml! MM MM mum lui mi

10 MILLI-4

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2 3 4

CENTllS IFTf

6

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7 S 9 10

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10 M LLI-'

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l 2 A 1 £

CENT» IFTI

€

RR

1 e £ 10

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10 M LLI-d

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l 2 4

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1 €

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7 6 £ 10

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10 MILLIMETERS

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Rulers to he cut out and used -for measurinff seeds.