Japan Flora: Perennial herb short-pubescent while young; stems erect, 40- 80 cm. long, 3-angled, the wings 1-2 mm. wide; leaves peti- oled, the stipules lanceolate, bifid, caudately long-acuminate, 10-25 nun. long, 1-3 mm. wide, the leaflets 2-6, linear to linear-lanceolate, 6-10 cm. long, 4-7 mm. wide, with nearly parallel nerves, the tendrils nearly always simple; racemes on peduncles 10-15 cm. long, 5- to 8-flowered; flowers 15-20 mm. long, purple, the lowest calyx-tooth lanceolate, nearly as long as the tube. May-June. Wet grassy places and thickets along rivers in lowlands.
Honshu, Kyushu. Korea, Manchuria, China, and e. Siberia.