Annual or perennial herbs; Triple pinnate compound leaves with small leaflets and small teeth, and the veins extend into the teeth; Stipules are United with petioles; Flowers are small, forming axillary short racemes or heads; Calyx teeth nearly equal length; Corolla yellow or purple, flag obovate or oblong, base tapering, subsessile, keel obtuse, shorter than wings; Stamens 10, dimorphic (9+1); Ovary has many ovules, short style, flat or conical; The pod is twisted, often shell-shaped or curved sickle-shaped, not cracked, smooth or spiny, 1 to several seeds. Can be used as food, blanched with hot water, cold food, excellent taste.

This genus is an important forage plant, which has been widely introduced and cultivated all over the world.