Small annual herbs, 5–20 cm tall; stems erect, simple or branched, quadrangular, glabrous. Leaves distinct 3–5-palminerved; sessile, lamina elliptic, apex obtuse, base cuneate, margins entire, glabrous, 0.7–2.5 x 0.3–1.2 cm. Flower solitary and axillary; pedicel 0.5–2 cm long, glabrous. Calyx 2.5–3 mm long, 5-lobed; lobes divided almost to the base, linear-lanceolate, apex acute, glabrous, except apex densely hirsute hairs, sparsely glandular inside calyx tube. Corolla 4–7 mm long, glabrous, except pubescent at corolla tube; upper lip ovate, emarginsate, 1.5–2 mm wide; lower lip 3-rounded lobes, 4–5 mm wide. Stamens 4, all fertile; posterior straight, glabrous, ca. 1 mm long; anterior filaments curved, 1.5–2 mm long, linear spure near the base, ca. 1 mm long; cleistogamous flowers often present. Capsules ellipsoid or subglobose, 2.5–4 x 1–3 mm, more or less equal to calyx lobes. Seeds numerous, cylindric, 0.28‒0.39 x 0.13‒0.21 mm, sulcate with prominent rib, slightly concave and irregular ridges
Widely spread over tropical to warm temperate regions from central to south-eastern Europe to eastern Asia
Open places in paddy fields, 200–400 m altitudes; flowering and fruiting July–March