Japan Flora: Tall perennial herb; stems rather stout, erect, often branched, 50- 100 cm. long, puberulent; leaves submembranous, broadly ovate to broadly lanceolate, usually narrowly ovate, 6-12 cm. long, 2.5-8 cm. wide, acuminate, rounded at base, obtusely toothed, puberulent on both sides, more densely so on nerves beneath, subsessile or the petioles 3-5 mm. long; cymes many-flowered, sometimes short-pedunculate; calyx 8-10 mm. long, with raised nerves, 5-fid, the teeth linear-lanceolate, acuminate, the 2 dorsal teeth connate on lower 1/3; corolla purple, 22-30 mm. long; nutlets obovate-oblong, compressed- trigonous, about 3 mm. long, loosely white-pilose on upper side, rounded at apex. July-Aug. Wet shaded slopes in mountains; Honshu, Shikoku.

var. yesoensis Fr. & Sav. Petioles about 1 cm. long; corolla about 30 mm. long, rarely white. Hokkaido and Honshu (centr. and n. distr.).  

f. albiflora Tatew. Flowers white.