A System for

Visually Classifying

Alfalfa Flower Color

Agriculture Handbook No. 424

C-.J

Agricultural Research Service

U.S. DEPARTMENT OF AGRICULTURE
CONTENTS

Introduction 1

Flower color inheritance 1

Factors influencing flower color classification 3

Joint pigmentation 3

Color intensity 4

Bud color . 5

Aging 5

Irregular petal color patterns 6

Vein color 6

Systems for flower color classification 6

Previous classification systems 6

New classification system 7

Literature cited 11

Washington, D.C. Issued May 1972

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

Washington, D.C. 20402. Price 30 cents

Stock Number 0100-1603
A System for Visually Classifying

Alfalfa Flower Color

By D. K. BARNES, research geneticist, Plant Science Research

Division, Agricultural Research Service

INTRODUCTION

Flower color inheritance in alfalfa has been studied more extensively than any of its other qualitative characters. Alfalfa flower

color, because of its extensive variation, has been used to identify

variety, plant breeding and genetic materials, and to distinguish

between self-pollinated plants and those resulting from crosspollination (6, 5).i According to Clement (3) and Pedersen (11),

flower color is often an important factor in the attractiveness of

alfalfa clones to insect pollinators. The usefulness and importance

of alfalfa flower color has been established; but the many hues,

patterns, and intensities of purple, yellow, and combinations of

purple and yellow pigments have caused difficulty in phenotypic

classification.

This handbook briefly describes the genetics of alflafa flower

color, discusses factors that influence alfalfa flower color classification, presents a system for visually classifying flower color, and

presents color prints to illustrate the various flower color classes.

FLOWER COLOR INHERITANCE

Cultivated alfalfa is an autotetraploid. Difficulties in working

with tetraploid genetics have limited the number of inheritance

studies in alfalfa, especially on traits controlled by two or more

genes, such as flower color. Results from genetic studies have

demonstrated a close relationship between the inheritance patterns for purple and yellow flower color in diploid and tetraploid

alfalfa. Therefore, in many instances, diploid species of Medicago

falcata L. and M, sativa L. have been utilized to help interpret

the more complicated inheritance patterns. All available information on the inheritance of alfalfa flower color was summarized

and reevaluated by Barnes (1). The data indicated that flower

color in alfalfa was conditioned by three types of major gene

effects and several types of modifying genes.

The major genes include one recessive gene (c) with tetrasomic

inheritance. The c gene is a basic color factor that, in the homozygous recessive condition, produces white-flowered plants that

1 Italic numbers in parentheses refer to Literature Cited, p. 11.
2 AGRICULTURE HANDBOOK 424, U.S. DEPT. OF AGRICULTURE

are devoid of all anthocyanin pigmentation in flowers, seeds,

stems, leaves, and roots. Purple flower color pigments are expressed in the presence of one or more dominant C alíeles. Chemical analyses of diploid alfalfa indicated that purple flower color

is due to a group of three anthocyanin pigments identified as

malvidin, petunidin, and delphinidin diglucosides. These three

pigments are inherited as a unit and are expressed when one or

more dominant alíeles of P gene are present. The tetrasomically

inherited P gene is present in purple-flowered M. sativa plants.

The homozygous recessive p genotype in the presence of dominant

C alíeles produces a cream flower color that does not interfere

with anthocyanin pigmentation in floral veins, seeds, leaves,

stems, and roots.

Genes responsible for producing yellow pigments can be classified as the third major type of alfalfa flower color pigmentation.

The origin of yellow flower color in alfalfa can be traced to M.

falcata. In diploid alfalfa the yellow pigments have been identified

as being primarily xanthophyll with a small amount of B carotene

present. Diploid genetic data suggest that yellow flower color is

controlled by at least three and probably four genes with accumulative effects. Only limited data are available concerning the

inheritance of yellow flower color pigments in tetraploid alfalfa.

However, a pattern of tetrasomic inheritance for at least two

genes (Yi and Y2) with accumulative effects is hypothesized.^ The

homozygous recessive condition of both the P and Y genes produces a cream-flowered plant. Joint pigmentation of the P and Y

genes produces phenotypes that have been commonly referred to

as variegated flowers. Variegated flower colors may range from

a very dark blue color to a green or yellow green.

Essentially no information is available regarding the inheritance of color intensity. Data presented by Soudah^ suggested

that the effects of the P gene were accumulative and that the

various intensities of purple could be due to specific genotypes;

that is, pppp = cream, Pppp = light purple, PPpp = purple,

PPPp = deep purple, and PPPP = very deep purple. However,

progeny tests needed to verify or disprove the theory have not

been conducted. Other evidence is available that suggests accumu-

. 2 Several loci are responsible for the expression of yellow flower color pigments, but for brevity in the following text, only one representative gene will

be used.

3 Soudah, R. E. TETRASOMIC INHERITANCE OF FLOWER COLOR IN ALFALFA,

Medicago sativa L. (Unpublished Ph.D. thesis. Copy on nie Dept. of Soils

and Crops, Rutgers Univ., New Brunswick, N. J.). 1962.
VISUAL CLASSIFICATION OF ALFALFA FLOWER COLOR 3

lative effects of dominant alíeles do exist in alfalfa flower color;

that is, crosses between cream-flowered plants and dark-orangeyellow plants produce progenies with intermediate yellow flower

color, and subsequent F2 segregations produce various intensities

of yellow flower color that can best be explained by assuming

accumulative effects of the Y genes. Modifying genes must be

considered as another source of factors that can affect flower color

intensity.

Several types of modifying factors are known to exist in alfalfa.

Nine anthoxanthin pigments have been chemically identified as

flower color modifying pigments in diploid alfalfa (i). Six of the

anthoxanthins were quercetin glycosides, and three were kaempferol glycosides. None of these pigments appeared to impart a

phenotypically significant color of its own, but they tended to act

as modifying genes when copigmented with the P or Y genes. No

association or linkage has been shown between any of the modifying genes (5).

Two additional types of modifying flower color characteristics

are purple bud color and floral vein color. Barnes and Cleveland

(2) reported that in diploids they had not observed the purple

bud color trait in unadulterated M. falcata, but it was often observed in yellow- and cream-flowered progeny from advanced generations of hybrids between M. falcata and M. sativa. The trait

was shown to be conditioned by two complementary genes. The

assumed genotype of pure M, falcata was BfBf bsbs and the assumed genotype of M. sativa was bfbf BsBs. Purple bud color is

produced by Bf Bs genotypes. Barnes and Cleveland also established that the presence of pigmented veins in the standard

petals of yellow-flowered diploid alfalfa was controlled by the

presence of one or more dominant alíeles of two duplicate genes

(Vsi and VS2). When both genes were homozygous recessive, no

floral vein pigmentation was observed. Barnes and Cleveland suggested that vein color in the wing petals was conditioned by a

separate gene.

FACTORS INFLUENCING FLOWER COLOR

CLASSIFICATION

Joint Pigmentation

Except for the pure purple, yellow, cream and white flower

colors, most of the flower color phenotypes are caused by varying

concentrations of two or more pigments being present in the same

flower. The most distinctive differences in alfalfa are due to the
4 AGRICULTURE HANDBOOK 424, U.S. DEPT. OF AGRICULTURE

joint pigmentation of purple and yellow pigments. Lesins (9)

suggested that in copigmentation the purple pigments were in the

epidermal layer of the flower, which in turn was over a background of yellow. However, Buker* suggested that the yellow and

purple pigments were both present in the same cells and that the

mosaic effect observed by Lfesins was caused by cell injury that

occurred when the epidermal cells were removed.

Extremely large numbers of copigmented genotypes are possible when it is considered that as many as five genes with major

effects and numerous genes with modifying effects, all with tetrasomic inheritance, exist. However, many of the differences between phenotypes are very subtle and not obvious to the naked

eye. Therefore, when differences in joint pigmentation are considered without the benefit of chemical analyses, similar phenotypes can be placed into several relatively distinct groups. These

groups, generally, can be described as blue, blue green, green, and

yellow green.

Color Intensity

Intensity of flower color varies considerably, regardless of the

type of pigments present in the flower. Purple pigmentation

varies among plants—^from a very deep purple to a very light

purple. Similarly, yellow pigmentation can vary from a dark

orange yellow (typical of M. fcUcata) to a very light yellow. The

inheritance of flower color intensity is not fully understood, but

it has been suggested that flower color intensity is influenced by

the accumulative effects of the dominant alíeles of the P and Y

genes. Sheridan and McKee (IS) used colorimetric measurements

to determine the effect of soil fertility, soil pH, and light on the

intensity of purple flower color. Only light appeared to be a significant factor. Purple flowers from field-grown plants were generally lighter than flowers grown in the greenhouse. Even though

environment can influence them, flower color intensities are stable

enough to be used in establishing subclasses within the primary

classes of purple, yellow, and variegated. However, color intensity could be responsible for misclassification of flower color

if a plant has a very intense purple color that masks a very low

level of yellow pigmentation. Such a plant would be classified

as purple instead of variegated.

* Buker, R. J. FLOWER COLOR INHERITANCE IN DIPLOID ALFALFA. (Unpublished M.S. thesis. Copy on file Dept. of Agronomy, Purdue Univ., Lafayette,

Ind.) 1960.
VISUAL CLASSIFICATION OF ALFALFA FLOWER COLOR 5

Bud Color

Purple bud color is not conditioned by the major purple flower

color gene (P) ; but to avoid misclassification, bud color should be

considered when flower colors are observed. Purple bud color is

characterized as having visible anthocyanin pigments at the tip

of the flower bud (pi. 1, A). This pigmentation usually disappears

as the flower opens. The purple bud trait is masked in purpleflowered plants but is very obvious on plants that have yellow

or cream flower colors. Because the pigments are faint and disappear rapidly, they do not usually interfere with flower color

classiflcation. However, cream- and yellow-flowered plants have

been observed in which the purple bud color is very intense and

traces of purple pigments are visible several days after the flowers

have opened. If this occurs, a decision must be made to determine

whether the purple pigment is caused by the bud color or by the

basic flower color gene. The best method for determining the

cause is to observe the distribution of the pigment in the flower.

If the purple pigment is uniformly distributed throughout the

opened flower, it can be assumed that the color is attributed to

the P gene. However, if the color is concentrated only at the tip

and edges of the standard petal and wings, the color can be attributed to the bud color genes.

Aging

The life of an untripped alfalfa flower ranges from 8 to 15 days,

according to Hanson (7). During this period, the flower color of

each floret is continually changing. Many, if not all, of the purple

pigments are very sensitive to sunlight and will begin to fade soon

after the flower opens. The yellow pigments appear to be more

stable than the purple pigments. Because of the aging process

in alfalfa flowers, the same age flowers must be used for all

flower color classiflcation. Flower age can be readily established

by the position of a floret on a raceme (pi. 1, C). One-day-old

flowers are the best age for flower color classification in the field.

In the greenhouse, flower colors may remain stable for 2 or 3 days,

depending on the conditions. Even though 1- or 2-day-old flowers

are used for classification, it is a good practice to observe several

faded flowers on the same plant for traces of yellow pigments.

This essentially eliminates the misclassification of plants that

may appear to be purple at first glance, but are actually variegated

(joint pigmentation of purple and yellow pigments).
6 AGRICULTURE HANDBOOK 424, U.S. DEPT. OF AGRICULTURE

Irregular Petal Color Patterns

Alfalfa flowers are formed by five petals : two wing petals, two

keel petals, and a standard petal. All of the petals are uniformly

colored in most alfalfa flowers. However, irregular color patterns

can be observed in some purple pigmented flowers. The most

frequently observed irregularity is in keel petals whose tops are

more or less intensely pigmented than the rest of the flower

(pi. 1, B). An unusual mutant, characterized by darkly pigmented

wing petals, cream-colored keel, and standard petals, is shown in

plate 2, A. Partial pigmentation of the standard petal (pi. 2, B)

is another unusual color pattern. None of these traits can be related to kno^vn flower color patterns, because their inheritance has

not been studied. Practical judgment must be used when classifying unusual flower colors. The flowers in plates 2, A and B were

classified as having purple flower color, because they lacked all

traces of yellow pigments and could not be classified as either

cream or white.

Vein Color

Most alfalfa flowers have pigmented veins in the standard

petals, and a few plants have pigmented veins in the wing petals.

In yellow and cream-colored flowers the veins are usually brown

(pi. 2, C), while in purple pigmented flowers the veins are purple

(pi. 2, D). Vein color usually does not contribute a great deal to

the total flower color, but the presence or absence of pigmented

veins or degree of vein pigmentation can be very useful identification characteristics. The presence of brown pigmented floral veins

in an otherwise Vhite' flower denotes cream flower color. The

presence of purple pigmented floral veins in an otherwise *white'

or cream flower generally denotes that the flower color should be

classified as a very light purple (pi. 2, D). However, it should be

pointed out that even though purple vein color and purple flower

color are closely associated, no studies have yet been conducted to

demonstrate pleiotropy.

SYSTEMS FOR FLOWER COLOR

CLASSIFICATION

Previous Classification Systems

A number of methods have been used for scoring alfalfa flower

color, such as the British Colour Council Horticultural Colour

Chart (5), Nickerson Color Fan (10), and the Munsel Color Key
VISUAL CLASSIFICATION OF ALFALFA FLOWER COLOR 7

(3). However, such systems based on solid colors have usually

proved difficult to use, because age of flowers, variable color patterns, and vein pigmentation tend to influence the results and

make classification very confusing.

Arbitrary systems of visual classification have often been originated by researchers for special studies. Three of these systems

are presented in table 1. Several additional schemes no doubt

can be found in the literature. In all of the classification systems

described, fiower colors have been arranged according to shade

and intensity of purple, yellow, and variegation (joint pigmentation of yellow and purple pigments). Each scheme phenotypically

classified plants, but the numerical scores usually did not reflect

any genotypic relationship among the various colors. Another

difficulty with the arbitrary classification systems is the discrepancy in descriptions and interpretations of colors among

workers. What is called blue by one worker may be considered as

purple by another.

New Classification System

Before attempting to design a new system for classifying alfalfa

flower color, I asked alfalfa scientists what type systems would

be most useful to them. The consensus of opinion was that we

needed a system of only a few phenotypic classes, each representTABLE 1.—Three previously proposed systems of flower color rating

for visually classifying alfalfa flower color'^

Numerical System System System

rating 1 2 3

1 Deep reddish purple Purple —

2 Deep purple Lilac Yellow

3 Strong purple Cream —

4 Moderate purple Light variegated Green-blue green

5 Light purple — —

6 Light violet Much variegated White or cream

7 Strong yellow green — —

8 Strong greenish yellow Light yellow Light purple

9 Brilliant yellow — —

10 White Dark yellow Dark purple

11, System proposed by Nittler, McKee, and Newcomer {10) \ 2, system

used by North Central Regional Plant Introduction Station, Ames, Iowa;

3, unpublished system used by D. K. Barnes, L. J. Elling, and A. G. Peterson

in studies on the attractiveness of alfalfa clones to pollinating insects, Univ.

of Minnesota.
8 AGRICULTURE HANDBOOK 424, U.S. DEPT. OF AGRICULTURE

ing specific genotypes arranged in order of their genetic relationship. The system should easily and accurately classify the ñower

color of individual alfalfa plants or plant populations by a numerical rating so that data could be arrayed according to percent of

plants in each ñower color class ; population means could be obtained and analyzed statistically; or flower color data could be

stored in a data retrieval system for future reference.

After considering the proposed requirements for a flower color

classification system and the problems involved with phenotypic

classification of alfalfa flower color, the writer designed the visual

classification system in table 2. The rating scale is similar in some

respects to those of previous systems ; however, primary emphasis

is given to the effects of major genes and less emphasis to effects

of modifying genes. The proposed system is intended to be more

meaningful than previous systems for comparing or averaging

flower color scores of individual plants of a variety or plant introduction. The proposed system deals more with gene frequency of

several major loci than with various allelic interactions at any

one locus. Also, the system is flexible because it can be used either

as a five-class system for general studies; or, in cases of clonal

identification and critical genetic studies, the secondary classes

can be used.

As mentioned earlier, word descriptions of color can sometimes

be misleading because all people do not associate colors in the

same manner. In this handbook, photographs of each flower color

subclass serve as color guides. Variations for color hue and color

patterns occur within nearly all subclasses; therefore, it was

postulated that groups of racemes illustrated the normal variability within each subclass better than could be done by using

only one typical raceme.

The theory for arranging the order of the primary flower color

groups as presented in table 2 was based on the fact that pure

M, sativa and pure M, falcata have dark purple and dark yellow

flowers, respectively. Variegated colors result from intercrosses

of purple and yellow flower colors. Therefore, purple and yellow

flower color classes should be located on opposite ends of any

color scale with the variegated types in the center. The next consideration was where to place white- and cream-flowered plants.

Usually these plants make up less than 1 percent of a population,

but they each represent distinct genotypes and must be given a

place in any flower color classification.

White flower color is produced by the homozygous recessive

genotype of the basic color factor (c) which blocks the expression
VISUAL CLASSIFICATION OF ALFALFA FLOWER COLOR 9

TABLE 2.—Proposed scale for visually scoring alfalfa flower color. Scale is

based on genotypic as well as phenotypic characteristics of the alfalfa

plant

Numerical Flower color class

rating and subclass Probable genotype

1 Purple or violet C P yyyy

1.1 Dark

1.2 Moderately dark

1.3 Light

1.4 Very light

2 Variegated C-__ P— Y___

2.1 Dark purple variegated

2.2 Maroon

2.3 Dark blue

2.4 Light blue

2.5 Dark blue-green

2.6 Light blue-green

2.7 Green

2.8 Dark yellow-green

2.9 Light yellow-green

3 Cream C pppp yyyy

4 Yellow C—_ pppp Y___

4.1 Very light

4.2 Light

4.3 Moderately dark

4.4 Orange

5 White cccc P— yyyy

of all purple and yellow flower color pigments. Since white flower

color does not give any identity of the genotypes for either the

P or r genes, it should be placed at one end of the scale to denote

a special genotype. All reported cases of naturally occurring white

flower color have been found in M. sativa. For this reason, the

white-flowered class could be placed at the purple end of the color

scale. However, it has been the consensus of a number of plant

breeders that they would prefer purple to be the number 1 class,

because of prior usage. Therefore, white flower color was placed

at the other end of the scale in class 5. The cream-flowered class

was placed between the variegated and yellow-flowered groups

because of its assumed hybrid origin and similarity to the very

light yellow flower color class.

The only primary flower color classes used in table 2 that may

be troublesome to correctly identify are the creams (pi. 3, A) and

the whites (pi. 3, B). White-flowered plants lack the basic color

factor and so are devoid of anthocyanin pigmentation in all tissues.
10 AGRICULTURE HANDBOOK 424, U.S. DEPT. OF AGRICULTURE

The genotype of the cream-flowered plants does not affect color

production of any organs of the plant except the flower. In direct

comparison of white and cream flowers, the cream flowers usually

will be more ivory colored than true white. However, in cases

when white flowers are not available for comparisons, the presence of pigmented floral veins or purple bud color can be used

as evidence of cream flower color. White-flowered plants occur

very seldom in natural populations, so as a general rule, plants

lacking purple and yellow pigments are usually cream rather

than white. If white-flowered types are found that lack pigmented

floral veins, positive identification can be made by producing a

few seed to check for white seed color or by testing stem tissue

for the presence of anthocyanin.

Most of the flower color subclasses used in table 2 are relatively

easy to identify. The four purple subclasses (pi. 3, C, D, E, and

F) are differentiated according to color intensity variations ; differences in hues of purple or violet are not considered. The

variegated class consists of nine heterogeneous subclasses, all of

which are characterized by varying degrees of purple and yellow

copigmentation. Flowers in the dark purple variegated subclass

(pi. 4, A) are usually dark purple when they first open, but the

purple pigments fade with age and the flowers become a smudgy

purple with faint traces of yellow pigmentation. The maroon

class (pi. 4, B) occurs rather infrequently and is characterized

by obvious joint purple and yellow pigmentation that lacks any

trace of blue or green color. The two blue subclasses (pi. 4, C

and D) are differentiated from each other on the basis of color

intensity. The blue-green subclasses (pi. 4, E and F) are quite

variable in color patterns, but they have a decided green color

over a blue background.

The blue-green flower colors are also separated by color intensity

into dark and light subclasses. Plate 5, A, illustrates the green

subclass. The green color is typical of Fi hybrids between M.

sativa and M. falcata. The yellow-green subclasses (pi. 5, B and

C) are predominantly yellow pigmented flowers with varying degrees of purple and green pigmentation. Intensity of yellow color

separates the dark and light yellow-green subclasses. The four

yellow subclasses (pi. 6, A, B, C, and D), like the purple subclasses, are differentiated only according to color intensity. The

orange-yellow subclass is characteristic of unadulterated M.

falcata flowers.

Differences in scores among observers occurred infrequently

during trial runs with the new classification system. No differ-
VISUAL CLASSIFICATION OF ALFALFA FLOWER COLOR 11

enees appeared when the five-class primary scale was used, and

usually only differences of 0.1 were observed when the secondary

scale was used.

The system was adopted by the Twenty-first Alfalfa Improvement Conference.^ It is presently being used by the North Central

Regional Plant Introduction Station of the U. S. Department of

Agriculture in their uniform recording and retrieval system for

use in evaluating alfalfa. The system was successfully used by the

NC-83 technical committee in a study to determine whether associations exist between seed yield in the North Central States,

California, and Idaho.

LITERATURE CITED

(1) Barnes, D. K.

1966. FLOWER COLOR INHERITANCE IN DIPLOID AND TETRAPLOID ALFALFA: A REEVALUATION« U.S. Dept. Agr.

Tech. Bull. 1353, 26 pp.

(2) , and Cleveland, R. W.

1964. FLORAL-BUD-COLOR AND VEIN-COLOR INHERITANCE IN

DIPLOID ALFALFA. Crop. Sci. 4: 174-177.

(8) Clement, W. M., Jr.

1965. FLOWER COLOR, A FACTOR IN ATTRACTIVENESS OF

ALFALFA CLONES FOR HONEY BEES. Crop Sci. 5: 267-

268.

(4) Cooper, R. L., and Elliott, F. C.

1964. FLOWER COLOR PIGMENTS IN DIPLOID ALFALFA. Crop

Sci. 4: 367-371.

(5)

1965. INHERITANCE OF FLOWER PIGMENTS IN DIPLOID ALFALFA AND THEIR RELATIONSHIP TO FLOWER COLOR

INHERITANCE. Crop Sci. 5: 63-69.

(6) Gartner, Alvaro, and Davis, R. L.

1965. EFFECTS OF SELF-COMPATIBILITY ON CHANCE CROSSING IN Medicago sativa L. Agron. Abstr. p. 12.

(7) Hanson, C. H.

1961. LONGEVITY OF POLLEN AND OVARIES OF ALFALFA.

Crop Sci. 1: 114-116.

5 W. H. Skrdla and others. Report of the committee on development of a

coordinated system of data retrieval for alfalfa introductions. Report of the

Twenty-first Alfalfa Improvement Conference. July 9-11, 1968, Reno, Nev.
12 AGRICULTURE HANDBOOK 424, U.S. DEPT. OF AGRICULTURE

(8) Hanson, C. H., Graumann, H. O., Elling, L. J., and others.

19i>4. PERFORMANCE OF TWO-CLONE CROSSES IN ALFALFA

AND AN UNANTICIPATED SELF-POLLINATION PROBLEM. U.S. Dept. Agr. Tech. Bull. 1300. 46 pp.

(9) Lesins, K.

1956. SOMATIC FLOWER COLOR MUTATIONS IN ALFALFA.

J. Hered. 47: 171-179.

(10) Nittler, L. W., McKee, G. W., and Newcomer, J. L.

1964. PRINCIPLES AND METHODS OF TESTING ALFALFA SEED

FOR VARIETAL PURITY. New York state Agr. Expt.

Sta. Bull. 807. 46 pp.

(11) Pedersen, M. W.

1967. CROSS-POLLINATION STUDIES INVOLVING THREE PURPLE-FLOWERED ALFALFAS, ONE WHITE-FLOWERED

LINE AND TWO POLLINATOR SPECIES. Crop Sci. 7:59-

62.

(12) Rumbaugh, M. D., Kehr, W. R., Axtell, J. D., and others.

1971. PREDICTING SEED YIELD OF ALFALFA CLONES. South

Dakota Expt. Sta. Bull. 38, 48 pp.

(13) Sheridan, Kevin P., and McKee, Guy W.

1970. COLORIMETRIC MEASUREMENTS OF PURPLE FLOWER

COLOR IN ALFALFA AS AFFECTED BY VARIETY, SOIL

PH, SOIL FERTILITY, LIGHT, AND SEED SOURCE. Crop

Sei. 10: 323-326.
Agriculture Handbook 424, U.S. Department of Agriculture PLATE 1

A, Purple bud color (right) ; open flowers from same plant with no obvious

purple pigmentation resulting from bud color (left) ; B, three racemes

demonstrating that color of keel petals can vary from color of wing and

standard petal; C, three racemes from same plant demonstrating effect

of age on color changes. Raceme on right just opening, raceme on left

5-6 days old.
Agriculture Handbook 424, U.S. Department of Agriculture PLATE 2

A, Unusual type of irregular flower color pigmentation in which wing

petals are purple while keel and standard petals are cream; B, unusual

type of irregular flower color pigmentation in which pigmentation pattern on standard petal is uneven ; C, brown vein color usually associated

with yellow and cream-colored flowers ; D, purple vein color usually associated with purple pigmented flowers.
Agriculture Handbook 424, U.S. Department of Agriculture PLATE 3

A, Cream- or ivory-colored flowers—class 3; B, white flowers lacking basic

color factor for all types of floral pigmentation—class 5; C, dark purple flowers—subclass 1.1; D, moderately dark purple flowers—stibclass

1.2; E, light purple flowers—subclass 1.3; F, very light purple flowers—

subclass 1.4.
Agriculture Handbook 424, U.S. Department of Agriculture PLATE 4

E F

Dark purple variegated flowers: newly opened flowers are dark purple

color, older flowers smudgy purple showing traces of yellow pigments—

subclass 2.1; B, maroon flowers—subclass 2.2; C, dark blue flowers:

newly opened flowers show purple color, older flowers are dark blue—

subclass 2.3; D, light blue flowers: newly opened flowers tend to show

purple color, older flowers are light blue—subclass 2.i; E, dark bluegreen flowers: various dark shades of green with blue backgfround

colors—subclass 2M; F, light blue-green flowers: various light shades

of green with blue background colors—subclass 2.6.
Agriculture Handbook 424, U.S. Department of Agriculture PLATE 5

A, Green flowers: some purple evident in newly opened flowers, blue colors

are not apparent—subclass 2.7; B, dark yellow-green flowers: darkly

pigmented yellow flowers with varying degrees of light purple pigmentation—subclass 2.8; C, light yellow-green flowers: lightly pigmented yellow flowers with varying degrees of light pigmentation—

subclass 2.9.
Agriculture Handbook 424, U.S. Department of Agriculture PLATE 6

A, Very light yellow flowers—subclass Jt.l ; B, light yellow flowers—subclass Jt.2; C, moderately dark yellow flowers—subclass 4-3 ; D, orangeyellow flowers—subclass U-Ua U.S. GOVERNMENT PRINTING OFFICE: 1972 0—452-942