Japan Flora: Rhizomes stout and branched, loosely tufted; leaves few, glabrous, obo­vate-oblong to oblong-oblanceolate, 15-40 cm. long, 5-13 cm. wide, very obtuse, gradually narrowed below to a petiolelike often reddish base, with short deltoid teeth, the midrib thick, white, usually reddish on under side; scapes terete, 40-80 cm. long, glabrous, the flowers whorled at intervals, the bracts lin­ear, the pedicels obliquely spreading, ascending in fruit, 2-3 cm. long; calyx narrowly cup-shaped, 6-8 mm. long, slightly accrescent after anthesis, 7-10 mm. long in fruit, 5-toothed; corolla rose-purple, rarely white, 2-2.5 cm. across, the tube narrow, 15-17 mm. long, the lobes spreading; capsules globose, as long as to slightly shorter tlian the calyx, 7-8 mm. long. Jane-July. Wet places along streams in mountains.

Hok­kaido, Honshu, Shikoku, Kyushu; frequently cultivated.  Taiwan.