Japan Flora: Tuber hemispheric; leaf solitary, the petiole terete, 10-25 cm. long; leaflets 5(-7), somewhat palmate, elliptic to oblong, abruptly short-cuspidate, cuneate at base, the terminal one short-petiolulate, 8-15 cm. long, 4-7 cm. wide, the adjacent lateral ones slightly smaller, usually decurrent on one side at base; scape 3-10 cm. long; peduncle 2-5 cm. long; spathe dark purple, without auricles, the blade oblong, scarcely narrowed at base, 8-13 cm. long, arching over the spadix and pendulous at tip, acuminate; spadix-appendage thick, clavate- cylindric, thickened below and truncate at base. May.