114 FODDER AND PASTURE PLANTS. 
ALFALFA (Medicago sativa L.) 
Plate 12; Seed, Plate 27, Fig. 34. 
Other English name: Lucerne. 
Botanical description: Alfalfa is a strongly perennial plant 
which is able to live thirty years or more under favourable conditions. 
It has a typical taproot; that is, the root system consists of a strong 
main root from which secondary side roots branch off. As there are 
no runners or creeping roots, all the overground branches start from 
the uppermost part of the taproot which generally protrudes above 
the ground and is known as the crown. With increasing age, the 
crown is apt to split into two or more branches, the upper ends of 
which are free and form a kind of tuft, sometimes of considerable 
circumference. The main root, which when old is an inch or so 
thick and rather woody, finds its way down to a considerable depth 
if the soil permits. On the roots are found the nodules, typical of 
the leguminous plants. They are on the finer branches and are 
clustered together into irregular bunches. The stems, which in old 
plants are exceedingly numerous, are generally from two to three feet 
high at flowering time. Asa rule, they are little branched, especially 
when the stand is dense. They are round below, more or less angular 
towards the top, and usually smooth. The leaves, which are alter- 
nate (that is, solitary at each joint and scattered along the stem), 
consist of three leaflets like those of Red Clover. The leaflets are 
rather narrow, two to three times as long as broad, and sharply 
toothed in their upper part. The middle one has a short stalk 
whereas in the cultivated species of Trifolium the central leaflet has 
no stalk. Occasionally leaves with four or five leaflets are found 
but not so often as in Red Clover. 
Biology of flower: The flowers are in a short and somewhat 
one-sided cluster. Each cluster contains from ten to twenty purple 
flowers of the ordinary leguminous shape, as described on page 15. 
They are fertilized by means of insects, especially certain kinds of 
bees. In all leguminous plants fertilized in this way, the stamens 
may come into close contact with the body of the insect. A bumble 
bee, for instance, visits Alfalfa. The nectar being in the bottom of 
the flower, it has to poke its proboscis down to the bottom of the 
flower tube. When it comes in contact with the lower part of the 
blossom, it works like a touch on the trigger of a gun. The cluster 
of stamens is set like a spring, and the touch throws the upper part 
of stamens and pistil forward with a jerk. An insect sitting on the 
