Plate 21; 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. As a 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 alternate (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 flower will thus be hit and his body powdered with pollen. When visiting another flower the same thing happens; the pistil comes in contact with the pollen on the body of the insect. The pistil is thus fertilized and more pollen is deposited on the insect. It is evident that cross-fertilization must frequently occur. As an insect will probably visit many flowers of a plant and travel from one plant to another, an individual may be fertilized by its own pollen as well as by pollen from another. Whether self- or cross-fertilization is most beneficial has, however, not yet been proved. Should a flower not be visited by any insect strong enough to open it, it will not be fertilized, not being able to explode by itself. The production of seed thus depends largely upon insects. The weather is also a factor, the flowers being almost insensible in cold, rainy weather, whereas in sunshine they will promptly respond to the slightest irritation. In common Red Clover the stamens and pistil gradually resume their original positions; as their elasticity is not affected by one or two visits, there is always a chance for proper fertilization. In Alfalfa there is no second chance; if an insect's first visit has no effect, the flower will not produce seed. After the pollen has been discharged, the pistil does not turn back to its original position; its top remains firmly appressed to the standard of the flower. It therefore develops into a curved fruit, although it is perfectly straight so long as it is enclosed within the flower. Its bending, which starts with the explosion of the flower, increases with its growth, and when the fruit is ripe it has the shape of a twisted shell.
Plate 21. ALFALFA or LOCERNE ( Medicago sativa l.).
Geographical distribution and history: The home of Alfalfa is Asia, probably the southwestern parts. It has been grown in Persia from time immemorial and is perhaps the oldest forage plant in the world. It was highly esteemed as fodder for horses, its Persian name meaning horse fodder. From Persia it was brought to Greece about 500 B.C., whence it spread to Italy. It was introduced to western Europe by way of northern Africa. The Arabs carried the plant to Spain in the seventh century. From Spain it was introduced into France. It is now grown in all European countries except the most northern. It was introduced by the Spaniards into Mexico, whence it spread to the western United States and to South America, and by the English and other colonists to the eastern parts of North America. It is now cultivated all over the United States. In Canada it is confined to small areas, southern Ontario and southern Alberta being the two districts where it is grown extensively.
Origin of name: Alfalfa is a Spanish version of the Arabian "Alfacfacah" which means "The best sort of fodder." Some have thought it to be derived from the Arabian "Al-chelfa," which means 'That which grows after something else," and is generally applied to plants which thrive after the spring growth has disappeared. The latter name would signify the ability of the plant to grow during the hot summer and perhaps refer to its power of producing many crops during the season. The first-mentioned derivation, however, is probably the correct one, the Spanish "Alfalfa" having been identified with the Arabian "Alfacfacah" in the 15th century by Fray Pedro de Alcala, a prominent specialist on the Arabian language.