Japan Flora: Annual, thinly pilose with spreading glandular hairs on upper portion; stems erect, more or less branched at base; leaves ovate or elliptic, 5-8 mm. long, 3-6 mm. wide, acute to subobtuse, rounded and weakly few-nerved from the base, entire, sessile; pedicels slender, 1-2 cm. long in chasmogamic flowers, sessile or less than 10 mm. long in the cleistogamic; calyx 3-4 mm. long, 5-parted nearly to the base, the segments linear-lanceo­late; corolla pale purple, about twice as long as the calyx; capsules ellipsoidal, 1.5-3 mm. long, shorter than the calyx; seeds oblong-lanceolate, about 0.5 mm. long, finely reticulate. July-Sept. Wet places and paddy fields.

Honshu, Shikoku, Kyushu. Korea (Quelpaert Isl.).