279. Flowers and seed. ВЂ” At blossoming time, each

branch and the main stem bear at least one cluster of

pea-shaped flowers that are purple in common alfalfa,

though some varieties bear yellow and others greenish

flowers. The calyx is five-parted, compound at the base

and sharply pointed at the single tips. Separate petals,

nine stamens in a bundle, one alone, and a compound

ovary that develops into a pod, form the other parts of

the flower. Growing pods are distinctly curled, making

from one to four distinct curves and bearing from one to

a dozen seed. As maturity approaches, the pods take

on a dark brown color and the seeds become yellowish,

Alfalfa 261

greenish-yellow, or brown. Though alfalfa seed is nat-

urally kidney-shaped, a large percentage of it is angular

in various ways, on account of the seeds touching each

other as they grow. Peas are flattened on opposite sides

due to lack of room ; but curling in the pod exerts pres-

sure on the corners, rather than on the sides or ends.

Failure to mature properly leaves some shrunken seeds;

others are brown with tough seed-coats. These are

usually slow to germinate or may even lack the power to

do so. The seeds are usually about one-sixteenth of an

inch in length and half that in width and thickness.

280. Varieties. — In adjacent parts of Asia, Africa,

and Europe a number of varieties of alfalfa grow wild.

In cultivation, however, only two distinct kinds find use.

One is erect, blue- or purple-flowered, and familiar ; the

other yellow-flowered, not well-known, rather creeping of

stem and stoloniferous, a quality absent in the common

alfalfa. The second, Siberian, has its chief value in

crossing with the ordinary plant to give resistant strains.

A number of strains have been taken from regions in

which they have been grown for a time long enough to

become adapted to climate, soil, culture, and use of that

section. These strains are : (1) " common," (2)

Turkestan, (3) Arabian, (4) Peruvian, (5) variegated,

and (6) Grimm. Half a century on the dry-farm has

given rise to the so-called dry-land alfalfa, which probably

differs but slightly from the common strain. None of

these are of special importance save Grinun, which resists

winter-killing to a remarkable degree. Variegated, a

cross with Siberian, has variouslv colored flowers.

Since, in general, adaptation to a locality determines

the value of a lot of seed, these cultivated varieties have

little value. Perhaps we may learn enough about them

to establish certain strains for particular conditions. As

262 The Principles of Agronomy

yet, 95 per cent of our crop continues to be " common "

alfalfa.

281. Distribution and adaptation. — Western United

States, Argentina, Chile, Peru, southern Europe, North

Africa, South Africa, Australia, and western central Asia

produce alfalfa extensively. All these sections are semi-

arid, with hot, dry summers and winters either not rigor-

ous or else snow-covered. The greatest production by

states in the United States is as follows : (1) Kansas, (2)

Nebraska, (3) Colorado, (4) California, (5) Idaho, (6)

Utah, (7) Montana, (8) Oklahoma, (9) Wyoming, and

(10) New Mexico.

A deep, fertile, well-drained soil pennits the greatest

development of the crop, especially when lime is present