Japan Flora: Glabrous annual; stems creeping and branched at base, ascending to erect and short-branched in upper part; leaves opposite, flat, obovate-oblong or obovate, sometimes nearly oblong, 5-10 mm. long, 3-5 mm. wide, rounded at apex, narrowed to the sessile base, with translucent cartilaginous margins; leaves of short upper branches smaller; flowers soli¬tary in axils, sessile, the bracteoles linear, as long as the calyx; calyx tubular-campanulate, about 1.5 mm. long, the lobes 4, narrowly deltoid, acuminate, spine-tipped; petals small; stamens 4; capsules ellipsoidal, not exserted, included within the calyx; styles slender, 0.5-0.7 mm. long, the stigmas capitate. Aug.-Oct. Paddy fields and wet places in lowlands;

Hokkaido (sw, distr.), Honshu, Shikoku, Kyushu; common. e. Asia, Malaysia, and India.