Herbs, annual, 10-30 cm tall. Stems succulent, decumbent to ascending, laxly branched, glabrous, angular. Leaves alternate, sparse; petiole 1-3 mm, glabrous; blade suborbicular, broadly ovate, elliptic, or lanceolate, 7-14 × 4-6 mm, both surfaces scabrous but glabrous, base cuneate or broadly cuneate, margin crenate or crenulate, apex rounded, obtuse, acute, or acuminate. Flowers axillary at leaflike bracts forming a lax raceme; pedicels (1-)2-2.7 cm, slender, glabrous; base with 2 lanceolate bracteoles ca. 3 mm. Hypanthium funnelform-campanulate, 2-3 mm, glabrous; calyx lobes linear or subulate, slightly longer than tube at anthesis, but shorter than tube in fruit, glabrous, entire. Corolla 2-lipped, pale blue or white, 4-8 mm; upper lobes erect, oblong-oblanceolate; lower lobes spreading, oblong-elliptic. Stamens connate above middle of filaments; filament tube glabrous; anther tube 1-1.5 mm, back glabrous, anthers all barbate at top. Capsule oblong or ovoid, 4-5 × 3-4 mm. Seeds numerous, 3-angular, dark brown. Fl. and fr. Jan-Dec.

Two subspecies are recognized.

Paddy fields, by water or among wet grasses in forests, wet places; below 800 m. Guangdong, Guangxi, Hainan, Taiwan, Xizang, Yunnan [Bangladesh, India, Japan (including Ryukyu Islands), Laos, Malaysia, Myanmar, Nepal, New Guinea, Sri Lanka, Thailand, Vietnam].