Alfalfa (/ æ l ˈ f æ l f ə /) (Medicago sativa), also called lucerne, is a perennial flowering plant in the legume family Fabaceae.It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as well as a green manure and cover crop.The name alfalfa is used in North America. The name lucerne is more commonly used in the United ...