Japan Flora: Thinly puberulcnt annual; stems 7-15 cm. long, ascending from a branched base; leaves ovate or narrowly deltoid-ovate, sometimes oblong, 1-2 cm. long, 6-12 mm. wide, subobtuse to obtuse, rounded at base，obtusely few-toothed, short-petiolate; flowers solitary in axils, the uppermost flowers forming a terminal cyme, the pedicels slender, ascending, 1-2.5 cm. long; calyx 4-5 mm. long, with 5 narrowly deltoid-acute shallow lobes; corolla pur­ple, about 1 cm. long; capsules oblong, slightly shorter than the calyx; seeds elliptic, obsoletely impressed-punctate.  Aug.-Oct. Wet cultivated fields and riverbanks in lowlands.

Hokkaido, Honshu，Shikoku, Kyushu; common. s. Korea, Ryukyus, Formosa, China, India, and Malaysia.