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Circular No 625
November 1941 * Washington, DIG. DerartenG

UNITED STATES DEPARTMENT OF AGRICU

Birdsfoot Trefoil and Big Trefoil

By Rotanp McKEd#, senior agronomist, and H. A. Scuoru, agronomist, Division
of Forage Crops and Diseases, Bureau of Plant Industry

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For a hundred years or more birdsfoot trefoil (Lotus corniculatus
L.) and big trefoil (Lotus uliginosus Schkuhr) have been used in small
plantings in the British Isles and in the countries of continental
Europe. They have recognized forage value and are grown in France,
Italy, Denmark, Germany, and elsewhere. In the more southern
countries they have been used for both forage and seed, whereas in
the north they are used principally for pasturage, but nowhere have
they gained major importance. In Australia and New Zealand
birdsfoot trefoil and big trefoil have been grown and have proved well
adapted in limited regions. According to Levy (2) 71t has been within
the last quarter of a century that these perennials have been grown
commercially in these countries. Birdsfoot trefoil is most extensively
used, although big trefoil is recommended for certain situations.
Both of these plants are native to the Mediterranean region and
northward to the Scandinavian Peninsula.

In the past few years birdsfoot trefoil (Lotus corniculatus) has
attracted attention in two widely separated sections of the United
States. Just how and when it was introduced and became established
in these areas is not known. In eastern New York and in western

1 Cooperative investigations of the Division of Forage Crops and Diseases, Bureau of Plant Industry,
U.S. Department of Agriculture, and the Oregon Agricultural Experiment Station.
2 Italie numbers in parentheses refer to Literature Cited, p. 13.

407385°—41 1

2 CIRCULAR 625, U. S. DEPARTMENT OF AGRICULTURE

Oregon, where it first became naturalized, it has spread until now it
is found over a comparatively large area. Floras of the eastern
United States first listed L. corniculatus about 1900 (1). In the
northwestern United States, it is first mentioned by Nelson (6) in
1917 as occurring in ballast near Portland. Specimens in herbaria
show that plants were collected in New Jersey as early as 1876; in
North Carolina and New York in 1885; and in Alabama in 1888.
The limited experience with both birdsfoot trefoil and big trefoil
in the United States follows the pattern of the experience in Europe,
Australia, and New Zealand, indicating that these plants are adapted
to at least limited sections and can be used for forage and pasturage.

Figure 1.—A pure stand of birdsfoot trefoil just past full bloom. Note the
similarity to a thick stand of alfalfa.

GENERAL DESCRIPTION

Birdsfoot trefoil is a long-lived herbaceous perennial with a well-
developed branching taplike root with few to many stems developing
from each crown. ‘The plants for the most part are erect or ascending
and attain a height of from 12 to 80 inches. The stems are compara-
tively slender, branch to some extent, and are moderately leafy.
Each leaf has three leaflets, borne at the end of a short petiole, and
has a cloverlike appearance. Usually the leaflets are obovate but
vary widely with varieties and are sometimes almost linear.

Big trefoil has the general characteristics of birdsfoot trefoil but
differs in having more flowers in each raceme and in having spreading
rhizomes that are lacking in birdsfoot trefoil. Both big trefoil and
birdsfoot trefoil have the general appearance of fine-stemmed alfalfa
Cissy).

BIRDSFOOT TREFOIL AND BIG TREFOIL ze

CLIMATIC REQUIREMENTS

From the information available it is concluded that birdsfoot trefoil
is best adapted to a temperate climate and will do much better in the
northern than in the southern half of the United States. Big trefoil,
from very limited observations, may not be quite so winter hardy as
birdsfoot trefoil, but plantings have survived and made good growth
as far north as Massachusetts. The following is quoted from the
Massachusetts Agricultural Experiment Station’s Eighth Annual
Report (4, p. 174).

Sulla (Hedysarum coronaria) and Lotus villosus* have for several years shown
a healthy and vigorous growth on our grounds; they stand our average winter
very well. Both deserve a serious trial for stocking pastures with a nutritious
growth. They shade the ground more efficiently in such localities than any of
our coarser clover varieties. Some subsequent statements of their composition
illustrate their high feeding value.

The most northern State reporting the growing of L. corniculatus is
Maine (3, p. 167). The following is quoted from that station’s
annual report of 1889:

Birdsfoot Clover— * * * Our plants were 14 inches high. They had
a tap root, sending up numerous branches with bright yellow flowers.

From 1905 to 1908 the Department, in cooperation with the
Washington (State) Agricultural Experiment Station at Pullman,
Wash., grew L. corniculatus and L. uliginosus in general trial plantings.
Both grew well, the former attaming stem lengths up to 30 and the
latter up to 22 inches, and although a dense, vigorous growth was
made, they were considered inferior to alfalfa.

At the Arlington Experiment Farm, Arlington, Va., plantings of
L. corniculatus in 1909 and later years have made good growth and
have attained stem lengths up to 30 inches. L. uliginosus at this
station has not made as large a growth as L. corniculatus but has been
quite vigorous. Seed of L. corniculatus sent by the Department to
the Illinois Agricultural Experiment Station was planted at a sub-
station in the southern part of the State and was grown from 1927
through 1929. This planting made good growth and appeared
reasonably well adapted to southern Illmois conditions.

In cooperation with the North Carolina State Agricultural Experi-
ment Station, plantings of L. corniculatus were maintained at States-
ville, N.C., from 1931 to 1935. The plants attamed a height of 18
inches and were reasonably vigorous. Other States in which suc-
cessful experimental plantings or naturalized growths have been
observed are California, Oregon, Michigan, and New York.

SOIL AND MOISTURE REQUIREMENTS

Birdsfoot trefoil is not exactmg as to soil requirements and does
well under a variety of soil conditions. It makes good growth on
sandy and light gravelly soils as well as on heavier clay loam and has
been observed growing in soils with moderate amounts of alkali.
In the Catskill section of eastern New York it 1s growing on poor

3 Three different plants have received the name Lotus villosus, namely, L. villosus Forsk., L. villosus Schur.
(now referred to the synonymy of L. corniculatus var. hirsutus Koch), and L. villosus Thuill. (now treated
varietally as L. wliginosus var. villosus (Thuill.) Lamotte). As no authority is given for the name in the

publication cited, it is not possible to know definitely which plant was meant, but inasmuch as L. wliginosus
var. villosus is the one most commonly handled commercially it seems likely that this is the plant referred to.

4 CIRCULAR 625, U. S. DEPARTMENT OF AGRICULTURE

gravelly loam soils of recognized low -productive capacity for local
standard crops. In the Pacific Northwest it is growing in similar
situations but also is found growing luxuriantly on the more fertile
lowlands of the coastal area. It is not particularly drought resistant
but will stand average drought conditions and is equal to most other
crops in this respect. Some writers, however, have claimed for it
unusual drought resistance.

In soil requirements the plants are very similar, but their moisture
demands differ. Big trefoil is suited to situations of greater moisture
than birdsfoot trefoil, in fact in places it will grow under quite swampy
conditions. Smith (9) refers to this species under the name Swamp
Horn clover, as follows:

It is a native of northern Europe, where it is esteemed for swampy meadow
eae: It is now cultivated in Wisconsin and Minnesota on sour, peaty, or muck
Sols

Recent reports + from these two States indicate that big trefoil no
longer occurs in Minnesota but that it persists in Wisconsin.

VALUE POR FORAGE

No feeding experiments have been conducted to determine the
relative value of birdsfoot trefoil or big trefoil for forage, but the
general experience of growers shows that they are entirely satisfactory
for this purpose. Both species have been used in European countries,
and general reports from Australia and New Zealand indicate that
they are highly regarded for use in pasture mixtures. In eastern New
York and in western Oregon farmers have pastured birdsfoot trefoil
and recognize its high feeding value. It also makes hay of good
quality. It is the practice of a number of farmers to grow birdsfoot
trefoil as a mixture with grass, and it is in such a combination that
it is most commonly fed. It is well adapted for use in this way and
such a mixture is considered very valuable.

In addition to making good hay and pasturage the season of growth
of birdsfoot trefoil and also big trefoil is such that good pasturage is
available in the latter half of summer when pasturage is usually short.
This feature is one of the strong assets of the crop .and tac it
especially valuable for use in pastures.

CHEMICAL ANALYSIS

The several published analyses of birdsfoot trefoil agree closely
with reference to the constituents that can be compared. Following
is an analysis of birdsfoot trefoil hay that was produced in the Rogue
River Valley, Oregon, in 1940, and is considered average for plants
in bloom:°®

Constituent: : Percent
Protein : Sootias bade 2 io MIN Rida, BE Ok Caee ON eee 14, 24
Bethe PES SG BP cy RE PE ges Sy See ae pe ee 2. 90
Fiber ccs cao: Be ie pe oe ars RRR eat Uy Se ey eee 29. 60
Calehuin tS: Sse in: FS a Se eh gee Le eee LehO
PHOSPhOrus 32sec 752" ee Se Sept ee nee le ge ee peer . 28

4 Correspondence on file in the Division of Forage Crops and Diseases.
5 Analysis by J. R. Haag of the Oregon Agricultural Experiment Station.

BIRDSFOOT TREFOIL AND BIG TREFOIL o

The Massachusetts Agricultural Experiment Station (4, pp. 179-
180) on June 21, 1889, cut plants of L. villosus® in full bloom for
analysis, which was reported as follows:

Percent

JSUIOWS HUN RES s, Nad aa oy SLY La a SS 2 ee Nee (one ee On ee 10. 68

DD TayeIieeG ben an ats yevk ries he 2) kph aged au ON wick ona 2 89. 32

ANALYSIS OF DRY MATTER

Constituent: Percent | Constituent—Continued. Percent
@ruderashe 2 2 ee 8. 23 Magnesium oxide_________ .336
@rude‘cellulose:. 22 == 5 _ = o. 24. 48 Herne Oxides sass tt oe < . 076
Crudetiataor rit Us eve 3. 00 Hodium-oxidel es 2 . 365
Crude protein (nitrogenous Potassium oxide__________ 2. 064
Matti eDypeap ie ae ee 13. 49 Phosphoric-acid= #2... 4_. - 688
Non-nitrogenous extract INitromeners a0 oe oie es Ee f -O30
IMMAGLCR a = awe ae TE 50. 80 Insoluble matter_________ . 888

It is evident from these analyses that both birdsfoot trefoil and
big trefoil have a relatively high protein content and appear to be
equal to clover and alfalfa in fat and minerals. |

SEED SETTING

The general conclusion of investigators who have studied seed
setting in Lotus species is that both birdsfoot trefoil and big trefoil
are practically self-sterile. Silow (8, pp. 239-240) who has more
recently given the subject consideration draws the following conclu-
sion:

Lotus corniculatus is practically self-sterile, but occasional plants set a few
seeds after self-pollination. Plants of L. major Smith (=L. uliginosus Schk.)
are, on the whole, incapable of spontaneous self-pollination; but after artificial
self-pollination practically all plants are self-fertile, some to a very high degree.
Thus these two perennial species are almost entirely dependent upon insect
visitors: for seed formation;; *.* \*. .

The fact that cross pollination is common in these species may ac-
count for the great diversity of forms that are readily apparent.
Although birdsfoot trefoil and big trefoil are both open pollinated
and. crossing of varieties within each species has been shown to be
beneficial to seed setting, it does not seem to have been demonstrated
that the two species hybridize.

SEED CHARACTERISTICS

The seed of both birdsfoot trefoil and big trefoil are small. Birds-
foot trefoil will average about 375,000 seed per pound and is a little
smaller than red clover seed. Big trefoil will average about 1 million
seed per pound and is a little smaller than white clover seed. The
color of the seed varies somewhat depending upon the stage of ma-
turity and the age subsequent to harvesting. In general, birdsfoot
trefoil seed is solid light to dark brown in color and big trefoil is a
solid greenish yellow to yellowish green, becoming brownish with age.
The weight of the seed in both species is about 60 pounds per bushel.
Seed of both birdsfoot trefoil and big trefoil germinate readily except

5See footnote 3, p. 3.

6 CIRCULAR 625, U. S. DEPARTMENT OF AGRICULTURE

oon hard seed. The available information on hard seed is very limited.
Germination tests of a number of commercial samples show as high
as 56 percent of hard seed in birdsfoot trefoil, and it is evident that
unless specifically scarified about half the seed or more will be hard.
Under favorable storage conditions both birdsfoot trefoil and big
trefoil retain their viability through a long term of years. Turner
(10) reports big trefoil seed germinating 9.6 percent after a lapse of
81 years.

SOURCE OF SEED

Seed of birdsfoot trefoil has been harvested in limited ee in
eastern New York for the past few years, and a small acreage was
harvested in 1940 in western Oregon and northwestern California.
No seed of big trefoil has been harvested in the United States. In’
New Zealand, France, Italy, Hungary, Denmark, and Germany,
and probably other European countries, one or both of these species
have been grown in a limited way and seed harvested. Big trefoil
seed has been produced in New Zealand, Germany, Italy, France,
and probably other European countries.

INOCULATION

In districts where birdsfoot trefoil is occurring naturalized, the
plants seem to be well inoculated. Experimental trials, however,
have shown that the plants do not become inoculated under all con-
ditions, and that artificial inoculation is frequently needed. It is
recommended, therefore, that artificial inoculation be given to all
new seedings.

FER EILIZER AND, LIME NEEDS

The sections in the United States where birdsfoot trefoil has come
into use are more or less deficient in lime, indicating that soils low
in this compound can produce the crop satisfactorily. The experience
in European countries bears out this conclusion and supports the
belief that this crop may have a place in at least limited areas where
the lime content of the soil is insufficient for most other legume crops.
It should be pointed out, however, that although -birdsfoot trefoil
does well on soils deficient in lime it has been shown that under such
conditions the use of this amendment often is beneficial. It has also
been demonstrated that superphosphate and potash are beneficial.
Robinson (7, p. 277) in the Empire Journal of Experimental Agri-
culture writes as follows:

The success of the crop depends to a icopsiderapie extent upon the supplies of

potash and phosphates in the soil. Given a sufficiency of these two plant-foods
the crop is capable of yielding well for a long time, periods of 9-20 years bens

not uncommon.
GROWING IN MIXT URES

In many cases it is desirable to grow birdsfoot and big trefoil in
mixtures rather than in pure stands. Most growers have followed
this practice and except when seed is the main interest it is highly
satisfactory. In pastures a mixture is to be preferred, and for hay

BIRDSFOOT TREFOIL AND BIG TREFOIL 7

both good yields and satisfactory quality can be attained by the use
of locally adapted combinations.

In New York timothy, orchard grass, red clover, alsike clover, and
birdsfoot trefoil in mixtures have given good results. In western
Oregon both big’ trefoil and birdsfoot trefoil have been satisfactorily
grown in combination with bentgrass, red clover, timothy, and
perennial ryegrass. In European countries mixtures of meadow
fescue, Bromus erectus Huds., and birdsfoot trefoil have been grown
successfully. Mixtures must be adapted to local conditions, and the
best proportion of the different grasses and legumes will vary (fig. 2).

SEEDING

Experimental results and experience of growers have indicated that
stands of both birdsfoot trefoil and big trefoil are sometimes difficult
to obtain. More difficulty has been experienced with big trefoil than
with birdsfoot trefoil but both need careful handling. A thorough
preparation and firming of the seedbed seems to be essential. Shallow
planting is also important. The seed should be covered as lightly as
possible and still insure enough moisture for germination. Broadcast
seeding and rolling to press the seed into the soil and firm the seed-
bed, so that moisture will be near the surface and in contact with the
seed, is perhaps the safest method to follow.

In the northeastern United States seeding should be made from
midsummer to early fall. Late-fall seedings may winter-kill. Spring
seeding is less desirable, as the seedling plants of both birdsfoot trefoil
and big trefoil grow very slowly and spring. weeds offer too much
competition. In the northwestern United States both east and west
of the Cascade Mountains the best time for seeding is from April 1
to May 15, depending on latitude and seasonal conditions.

When seeding alone and a full stand is desired, birdsfoot trefoil
should be seeded at from 8 to 12 pounds of good seed per acre and
big trefoil 4 to 6 pounds per acre. In mixtures with grasses these
figures can be greatly reduced. In New York some growers use but
1 pound of birdsfoot trefoil in a general mixture when the field is to
be left down for a term of years. With time the stand of birdsfoot
trefoil thickens and displaces some of the other plants in the mixture.

HARVESTING FOR FORAGE

Birdsfoot trefoil can be harvested and handled with ordinary farm
machinery and is commonly cut with a mower and raked and handled
as clover or alfalfa. Thin stands can be raked and handled quickly,
but heavier stands require some time for proper drying.

In cooperative experimental plantings at the Michigan Agricultural
Experiment Station, yields of hay were obtained amounting to 2 tons
per acre for the first cutting and 1,500 pounds for the second. Lime,
phosphate, and potash were applied to these plots and no doubt
increased the yield, but on poor, badly eroded, nearby areas receiving
only lime, good growth had been made. In cooperation with the
Illinois Agricultural Experiment Station, plantings at one of the sub-
stations in southern Illinois yielded 3.81 tons dry weight per acre in
1929. These plantings were established in 1927.

CIRCULAR 625, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 2.

A good stand of birdsfoot trefoil in mixture with grasses.

BIRDSFOOT TREFOIL AND BIG TREFOIL 8)

European writers report yields comparable to those obtained in
the United States at the stations reporting, and the experience of
growers in this country justifies the statement that where birdsfoot
trefoil does well, good yields can be expected and that two cuttings
for bay can be made. Although nearly 4 tons of hay per acre can be
obtained sometimes, it is probable that from 1 to 2 tons per acre is
nearer the average.

HARVESTING FOR SEED

Birdsfoot trefoil and big trefoil are both difficult to harvest for
seed. The seed ripens unevenly, and one plant will have both green

FicurE 3.—Birdsfoot trefoil with well-developed seed pods and flowers on the
same plants.

and ripe pods at the same time (fig. 3). When ripe, the pods open
easily, and this results in considerable loss of seed. In order to get
maximum seed yields, it is necessary to watch the plants closely and
to harvest when the maximum of seed is sufficiently mature. This
will be when the first pods are well browned and a goodly number have
turned a dark-violet color. The plants will still be green. Cutting
can be done with a reaper or a mower with or without swather attach-
ments. The cut material should be windrowed, then put in shocks,
and later stacked or threshed, depending on facilities available. The
seed immediately after harvest should be watched closely to prevent
damage, as the moisture from the immature seed may cause molding.

~ Seed yields vary, but 100 pounds of clean seed per acre is the usual

quantity saved by the few growers who have harvested the crop in

A

10 CIRCULAR 625, U. 8. DEPARTMENT OF AGRICULTURE

the United States. _ Yields between 200 and 300 pounds per acre have
been reported from France, but it is probable that these were maximum
yields.

PASTURAGE

Birdsfoot trefoil and big trefoil serve well in pastures in sections to
which they are adapted. The plants are palatable and nutritious
and seem to be particularly well suited for growing with grasses.
Being long-lived perennials when once established in pasture mixtures
they endure for a term of years. In western Oregon big trefoil has
been in experimental plots that have been grazed and cut for hay

Figure 4.—Dairy cows on birdsfoot trefoil and grass pasture.

for nearly 20 years, and the stand and growth are still good. In
eastern New York farmers are grazing birdsfoot trefoil and report
entirely satisfactory results. The plants stand trampling and graz-
ing well and livestock have done well on birdsfoot trefoil pasture
(fig. 4). No experimental data are available on the comparative
value of birdsfoot trefoil for pasturage, but general information indi-
cates that it is probably equal to alfalfa, clover, and other standard
legumes. ‘

European writers differ in some minor details regarding the value
of birdsfoot trefoil for pasturage, but all agree that it is a valuable
plant. Some of the features stressed by these writers are disease
resistance, drought resistance, longevity, and the fact that it will
grow under conditions where clover fails. It is also pointed out that
birdsfoot trefoil furnishes succulent pasturage in mid to late summer
at a time when most other plants are making little or no growth.
This latter characteristic appeals strongly to those in the United

BIRDSFOOT TREFOIL AND BIG TREFOIL ll

States who have used it for pasturage, and it is one of the qualities
that adds greatly to its value.

ENEMIES

Several of the common insect pests of clover and alfalfa have been
reported to occur on birdsfoot trefoil in Europe and Russia, although
no serious injury by them has been mentioned. These insects also
occur in the United States, but the only material injury by them
reported in this country was a case reported by Monteith and Hollo-
well (5) in which nursery rows “were heavily infested with the potato
leafhopper” and showed injury similar to that caused on alfalfa
by this insect.

DESCRIPTION OF VARIETIES AND FORMS

A number of varieties and forms have been described under both
Lotus uliginosus and L. corniculatus. L. corniculatus in particular is
extremely variable and, even from seed used for commerical plantings,
plants that differ widely are usually present. Under natural con-
ditions regional strains have developed, and these constitute the
many variants that have been given varietal and form designation.
For the most part shape of leaflets and habit and size of the plants
have been the basis of differentiation, but in some cases color and
number of flowers have been recognized. The following descriptions
and keys give the specific characters that separate species, varieties,
and forms and indicate the range of variation that exists.

The characteristics that distinguish L. corniculatus and L. uliginosus
from all other Lotus species are as follows:

Styles not dentate; flowers yellow; calyx campanulate; teeth equal and equaling
the tube; leaves not dotted or revolute; banner equaling the wings and keel;
bracts three; stem of keel shorter than the keel.

The only characteristics definitely distinguishing the two species
are the rhizomes and flowers. The definite features of these are as
follows:

Flowers usually 8 to 12 (rarely 6 to 7); rhizomes spreading.
L. uliginosus Schkuhr.

Flowers 5, sometimes 6, and rarely 7; rhizomes not spreading.
; L. corniculatus L.

L. uliginosus is only moderately variable and but two varieties
have been described. The following key gives the characteristics
separating these:

Miantsismooti’ or nearly so;.--_=-->--< ...=-+ = Pus, Re var. glabriusculus Bab.
Plants hairy = ahGd Seep th ie Ra sa oe var. villosus (Thuill.) Lamotte.

L. corniculatus is extremely variable, and alarge number of varieties
have been described. Many of these were originally given specific
rank. The following key indicates the wide range of variation and
gives the principal characteristics distinguishing the different varieties
and forms.

12 CIRCULAR 625, U. S. DEPARTMENT OF AGRICULTURE

A. Leaflets obovate to oblong, large or small.
B. Plants large, usually with 5 flowers, stems mostly smooth, leaflets
midlarge.
C. Stems smooth or slightly hairy.
D. Leaflets smooth, or with few scattering hairs.
Calyx teeth about as long as the calyx tube
var. arvensis (Schkuhr) Ser.
Stems ascending, long internodes.
Leaflets very large.
Flowers 1 em. long, plants robust 3 to 5 dm. high
f. silvaticus Baumg.
Flowers over 1 em. long, plants 3 to 4 dm. high
f. grandiflorus Rouy.
Leaflets medium or small.
lueatlets.:medium:_ 'o2s-ui2 hs f. genuinus Posp.
Flowers reddish yellow to red
f. rubriflorus Lamotte.
Flowers yellow with red keel
f, variegatus A. and G.-
Weatlets smaliless ase f. parvifolius Peterm.
Stems decumbent, short internodes___f. alpestris Lamotte.
Calyx teeth about one-third as long as the calyx tube
var. microdon Peterm.
D. Leaflets haviny or with long ciliate hairs.
- Plants ordinary type, but leaflets long ciliate
var. ciliatus Koch.
Leaflets small, thick stems, branches decumbent
var. crassifolius (Pers.) Ser.
Leaflets very small, 3 to 6 mm. long__f. parvifolius Rouy.
C. Stems densely hairy.
Stems ascending, 2 to 4 flowers._____________ var. hirsutus Koch.
Plants very dense, medium-size leaflets
f. pilosissimus (Schur) Rouy.
Plants procumbent, small leaflets.____________ f. minor Rouy.
Stemsidecumbent ss] eee ee var. delorti (Timb.) Rouy.
Stems much branched, medium size leaflets, flowers small,
brighteyellowa2+2 242 eee eee if symmetricus (Jord.) Rouy.
Stems moderately branched, leaflets very small
f. parvifolius Rouy.
B. Plants small with 1 to 3 flowers, stems more or less hairy, leaflets small
var. alpinus Ser.
A. Leaflets lanceolate to linear, small.
Calyx teeth much longer than the short calyx tube
var. preslit (Ten.) A. and G.
. Plants medium large, entirely without hairs___f. glaber (Rouy) A. and G.
Plants/smally quitethainys ==! = ees <2 f. sibthorpit (Rouy) A. and G.
B. Calyx teeth shorter or little longer than the calyx tube.
Plants medium or large.
Plants rather long, hairy, 2 to 5 dm. high
var. major (Scop.) Brand.
Plants*clabrous2: 2 5 Ay 5" eae ere ee eee var. tenutfolius L.
Stems 0.6 to 1.5 dm. long, upright
f. sabulicola (Rouy) A. and G.
Stems 4 to 8 dm. long.
Stems decumbent, branches elongated
f. longicaulis (Martr.-Don) A. and G.
Stems erect, flower racemes with very long peduncle
f. pedunculatus (Cav.) Rouy.
All parts fine, leaflets small______ f. parvifolius Rouy.
Leaflets rather thick or fleshy
fc eraseiioline (Lamotte) A. and G.
Plantswiery.smallas 2 sen eee eee var. microphyllus Hausskn.

BIRDSFOOT TREFOIL AND BIG TREFOIL 13

LITERATURE CITED

Britton, N. L.
1901. MANUAL OF THE FLORA OF THE NORTHERN STATES AND CANADA.
1080 pp. New York.
Levy, E. Bruce.
1918. THE BIRDSFOOT TREFOILS. New Zeal. Journ. Agr. 17: 347-351,
illus.
Maine AGRICULTURAL EXPERIMENT STATION.
1890. EXPERIMENTS WITH FORAGE PLANTS. Meine Agr. Expt. Sta. Ann.
Rpt. 1889: 161-171.
MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION.
1891. EXPERIMENTS WITH FIELD AND GARDEN CROPS. Mass. Agr. Expt.
Sta. Ann. Rpt. 1890: 169-186, illus.
MonTeEITH, JOHN, JR., and HoLLOWELL, E. A.
1929. PATHOLOGICAL SYMPTOMS IN LEGUMES CAUSED BY THE POTATO
LEAFHOPPER. Jour. Agr. Res. 38: 649-677, illus.
NeEtson, J. C.
1917. THE INTRODUCTION OF FOREIGN WEEDS IN BALLAST AS ILLUSTRATED
BY BALLAST-PLANTS AT LINNTON, OREGON. ‘Torreya 17: 151—160.
Rosinson, D. H.

1934. BIRDSFOOT TREFOIL IN AGRICULTURE. Empire Jour. Expt. Agr. 2:
274-283.
Sttow, R. A.

1930. SELF-FERTILITY OF LoTUS sPP. Welsh Plant Breeding Sta., Aberyst-
wyth [Bul.], ser. H., 12: 234-240.
SMITH, JARED G.
1900. FODDER AND FORAGE PLANTS EXCLUSIVE OF THE GRASSES. U.S.
Dept. Agr., Div. Agrostol. Bul. 2, 86 pp., illus. [Revised.]
TuRNER, J. H.
1933. THE VIABILITY OF SEEDS. Kew Roy. Bot. Gard. Bul. Misc. Inform.
1933: 257-269.

ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
WHEN THIS PUBLICATION WAS EITHER FIRST PRINTED OR LAST REVISED

DCCL ELON: Of PAGTIC UNLUT Ca ee ae eae eae CLAUDE R. WICKARD.

Under Secretary 2255 2. | a a ae Paut H. APPLEBY.

Assistant Secretary == See ee eee GROVER B. Hitt.

Directorsof, Information 22 eae a ree Morss SALISBURY
Director-ofelaienszon: Won. M. L. Witson.

Director of. Finance. 2238 = ee eee W. A. Jump.

Acting Director of Personnel__-____-_______~ JAMES L. BUCKLEY

Dijector of iescar clice a a JAMES T. JARDINE.

Director of Marketing 2 as ae ere Roy F. HENDRICKSON
Solicitors 5k 35 fe SER en AS eee a ee Mastin G. WHITE.

Land “Use Coordinao eS eee M. S. EIsENHOWER. |

Office of Agricultural Defense Relations___.__. M. Ciirrorp Townsenp, Director
Office of Plant and Operations_____-_-_-_-___- ARTHUR B. THATCHER, Chief.
Ojjiceof-C5C. C Aciuites see eae FrEeD W. MorreE 1, Chief.
Office of Experiment Statrons________---_--- James T. JARDINE, Chief.
Office of Foreign Agricultural Relations__-___- Lesitig A. WHEELER, Director.
Agricultural Adjustment Admintstration_____ R. M. Evans, Administrator.
Bureau of Agricultural Chemistry and Engi-

TOCCTUTAG (aces SPA pas ea RS NE MES OF RCY SS Pe Henry G. Kniaut, Chief.
Bureau of Agricultural Economics__-----~--- Fe lornmy. ney.
Agricultural Marketing Service___---------- C. W. KitcHen, Chief.

Bureau of Animal Indusiry______-.-_---_-- JoHN R. Mouter, Chief.

Commodity Credit Corporation_____-_-____- J. B. Hutson, President.

Commodity Exchange Administration___._____ JosEpH M. MeEnut, Chief.

BureauiojoDatr yp naus ny =e a ee O. E. REEp, Chief.

Bureau of Entomology and Plant Quarantine. P. N. ANNAND, Chief.

Farm Credit Administration___________---- ! A. G. Buack, Governor.

Farm Security Administration. ________-__- C. B. Batpwin, Administrator.

Federal Crop Insurance Corporation __-___-_- Leroy K. Smitu, Manager.

Pores Sr ueCe ees 5 Nae ae ee psy ee Ss Ear_Le H. Crapp, Acting Chief. .

Bureau of Home Economics__----_-----___- Louise STANLEY, Chief.

LADTOTY ce Se one ee ak Se eee eee RaupH R. SuHaw, Librarian.

Bureau of Blantandusiy =e ee E. C. Aucuter, Chief.

Rural Electrification Administration ____ ~~~ - Harry Suattrery, Administrator.

Soil Conservation Service = ee H. H. Bennett, Chief.

Surplus Marketing Administration ___-_-_-___- Roy F. HENDRICKSON,
Administrator.

This bulletin is a eontribution from

Bureauso, Blan indus E. C. Aucutsr, Chief.
Division of Forage Crops and Diseases___. OLAF S. AAMopT, Head Agronomtst,
In Charge.
14

U. S. GOVERNMENT PRINTING OFFICE: 1941

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