Japan Flora: Biennial, soft, slightly pubescent herb; stems slender, ascending from a procumbent, branched base, 10-25 cm. long; leaves with petioles 2-5 cm. long, the stipules free, ovate, 3-6 mm. long, acute, the leaflets 9-11, thinly membranous, obovate to elliptic, 8-15 mm. long, rounded to emarginate; racemes umbellike, the peduncles 10-20 cm. long; flowers 7-10, about 12 mm. long, reddish purple, rarely white, the pedicels 1-2 mm. long; calyx about 4 mm. long, loosely white-pubescent, the teeth lanceolate, shorter than the tube; legumes erect or ascending in one direction, subsessile, blackish, 2-25 cm. long, about 4 mm. wide, glabrous, gradually beaked. Apr.-June.
Very commonly cultivated for green manure in rice-fields, occasionally naturalized in our area. Formosa and China.