a deep-rooted perennial plant (Medicago sativa) of the pea family, with small divided leaves, purple cloverlike flowers, and spiral pods, used extensively for fodder and pasture and as a cover crop
See alfalfa in American Heritage Dictionary 4
(ăl-fălˈfə)
noun
A southwest Asian perennial herb (Medicago sativa) having compound leaves with three leaflets and clusters of usually blue-violet flowers. It is widely cultivated as a pasture and hay crop.