Japan Flora: Coty­ledons hypogeal; rhizomes slender, creeping, elongate; stems slender, nearly glabrous or retrorsely appressed-pubescent while young; stipules broadly linear, 3-nerved, 3-4 mm. long, acute, the leaflets thin, glabrous above, whitish and loosely appressed short-pilose beneath, the terminal leaflet narrowly ovate, 6-10 cm. long, 3-4 cm. wide, obtuse to subacute, the stipels subulate, about 1 mm. long; racemes pedunded, rather many-flowered, 2-5 cm. long, sometimes solitary or in pairs in axils; flowers 15-20 mm. long; calyx tubular, glabrescent, obliquely truncate at apex； legumes 3- to 5-seeded, oblanceo­late, terete, 4-5 cm. long, 7-8 mm. across, glabrous, inflated over the seeds. Aug.-Sept. Thickets and forest borders.

Honshu, Kyushu.