Japan Flora: Glabrous whitish or glaucous annual or biennial; stems much branched, 4-angled, 10-30 cm long; leaves opposite, ovate to narrowly  lanceolate, 1-2.5 cm long, 5-15 mm. wide, spreading, entire, acute to subobtusc, rounded at base, sessile; flowers solitary, axillary, the pedicels 3 cm. long; calyx-segments linear-lanceolate, long-acuminate, 6 mm. long, 1-ribbed; corolla blue-purple to reddish, 1-1.3 cm. across, the lobes obovate-orbicular, often ciliolate; capsules globose, about 4 mm. in diameter; seeds dark brown, about 1 mm. across, densely warty. Mar.-May.

Honshu (Izu Is­lands and westw.), Shikoku, Kyushu. Ryukyus, Formosa, and temperate and tropical regions generally.