Japan Flora: Slender, green, perennial;  stems erect, branched, 20-40 cm. long, angled, glabrous or loosely spreading-pubescent; cauline leaves reniform-cordate or cordate, 1-2 cm. wide, rounded at apex, few-toothed, pubes­cent on both sides, petiolate; floral leaves ovate or narrowly so, 1-2 cm. long, 5-15 mm. wide, obtuse, nearly sessile; calyx 2.5 mm. long in anthesis, 5-6 mm. long in fruit, spreading-pubes­cent; corolla white, 7-8 mm. long, the upper lip about half as long as the erect lower lip; nutlets wing-margined, about 2 mm. across inclusive of the wing, toothed, the lower surface with long linear-filiform white tubercles, the upper surface loosely papillose. May.

Honshu (Awa Prov. and westw.), Shikoku, Kyushu. Ryukyus.