Japan Flora: Glabrous perennial herb from slender creeping rhizomes 3-4 mm. in diameter; stems 20-40 cm. long; leaves lanceolate to narrowly oblong, 6-8, 7-12 cm. long, 1-4 cm. wide, acuminate, narrowed to a subsessile base; peduncles 1-flowered, 5-15 cm. long, erect; outer tepals 4(-5), broadly lanceolate to narrowly ovate, green, spreading, (2-) 3-4 cm. long, (0.5-) 1~1.5 cm, wide, acuminate, the inner ones 4(-5), filiform, yellow, reflexed after anthesis, 1.5-2 cm. long; stamens 8-10, slightly longer than the inner tepals, the filaments nearly filiform, 5-7 mm, long, the anthers linear, 5-8 mm. long; the free portion of the connective prominent, filiform, about 5-7 mm. long; styles usually 4; ovary dark purplish brown June-July. Woods in mountains;

Hokkaido, Honshu, Shikoku, Kyushu. Sakhalin, Korea, China, and Siberia.