_The Rabbit-Foot, or Stone Clover (Fig. 247). (T. arvense.)_--This is another clover not easily recognized as such. It grows a foot or more in height and has erect branches. The leaflets are narrow and all arise from the same point. The flowerets occur in long, dense heads. The calyx is very silky, and the lobes are longer than the white corollas, thus giving the flower-head a soft, hairy look, something like the early stages of the blossom of the pussy willow. Because of its appearance it is often called "pussy clover." THE MEDICS. (_Medicago._) _Alfalfa (Fig. 248). (Medicago sativa.)_--This is the veteran of all the clovers, for it has been under cultivation for twenty centuries. It is a native of the valleys of western Asia. In America it was first introduced into Mexico with the Spanish invasion. It was brought from Chile to California in 1854, where it has since been the most important hay crop. In fact, there is no better hay than that made from alfalfa. It was probably introduced into the Atlantic States from southern Europe, and has grown as a weed for many years in certain localities in New England and the Middle States; only recently has it been considered a practicable crop for this climate, although it was grown in Jefferson Co., N. Y., in 1791. Its special value is that it is a true perennial, and may be cut three times or more during a season, and when once established it withstands hot, dry weather. It is of marvelous value to the semi-arid regions. The alfalfa flower is blue or violet, and grows in a loose raceme. The plant grows tall and its stems are many branched. This and all these medics are introduced from Europe. _Black or Hop Medic. (M. lupulina.)_--This would hardly be called a clover by the novice. The long stems lie along the ground, and the tiny yellow flower-heads do not much resemble the clover blossom. It is a common weed in waste places in our State. It is perennial. _The Toothed Medic. (M. denticulata.)_--Instead of having the yellow flowerets in a dense head, this species has them in pairs or perhaps fours, or sometimes more. It is widely distributed as a weed, and is also introduced as a pasture plant for early grazing. It is of little value as hay. _The Spotted Medic. (M. Arabica.)_--This very much resembles the preceding species except that the leaves are likely to have on them conspicuous dark spots near the center. Like the preceding species it is an annual and a weed, and has also been introduced as a plant for early grazing. This and the toothed medic are known to farmers under the name of bur-clover. The reason for this name is found in the seed-pod, which is twisted in a spiral and has an outer margin of curved prickles. [Illustration: _Fig. 248. Alfalfa, foliage and flowers._] THE MELILOTS, OR SWEET CLOVERS. (_Melilotus._)