Description from Flora of China
Herbs perennial, twining or suberect. Leaves pinnately 3-foliolate; stipules basifixed, reflexed, persistent; stipels lanceolate. Racemes axillary, nodes of rachis swollen. Calyx campanulate, 2-lipped, upper lip entire or emarginate, lower 3-lobed. Corolla purple or white; standard orbicular, reflexed, auriculate at base, with 2 callosities on inner surface; wings broadly ovate; keel incurved at right angle. Stamens diadelphous; anthers uniform. Style abruptly upturned, laterally compressed, bearded in upper part; stigma terminal. Legumes obliquely oblong-falcate, compressed, with minute warts along both sutures, shallowly septate between seeds within. Seeds slightly compressed, with white aril.
One species: native to Africa, cultivated throughout the tropics including China.
(Authors: Wu Delin (吴德邻 Wu Te-lin); Mats Thulin)