This species is disticts by having serrate leaves, whitish blue or violet corolla and 2 fertile stamens and 2 yellowish stamonodes.
Annual small herbs, (2)–5–25–(38) cm tall; stems erect, diffuse, decumbent or prostrate, quadrangular, glabrous, somewhat rooting at the nodes. Leaves pinnately nerved; sessile to subsessile; lamina lenceolate-oblong, oblanceolate or somewhat obovate, 0.7–5 x 0.3–1.5 cm, apex acute or often rounded, base attenuate, margins serrate, non-aristate teeth, glabrous. Flower terminal, lax raceme or solitary and axillary; pedicel glabrous, stout, erecto-patent, 5–20 mm long; bracts linear-lanceolate, 1‒5 mm long or leaf-like. Calyx 3–7 mm long, tubular, 5-lobed; lobes divided almost to the base, linear-lanceolate, apex acuminate, glabrous. Corolla pale purple or light blue, 5–14 mm long; upper lip oblong, apex rounded or retuse, 2 – 4 mm wide; lower lip broadly 3-rounded lobes, 5–14 mm wide. Stamens 2 fertiles, 2 staminodes; posterior filaments straight, 1.8‒2 mm long, glabrous; anterior filaments yellow, filliform, straight or hooked at apex, 1.7‒2.4 mm long, woolly hairs along to corolla tube. Capsules cylindric, apex acuminate, 4–18 x 0.8–1.6 mm, longer than calyx lobes. Seeds numerous, ovoid, obovoid, narrowly ellipsoid, ellipsoid or subglobose, 0.25‒0.45 x 0.20‒0.33 mm, reticulate with rounded concave.
India, Sri Lanka, Nepal, Myanmar, Japan, Laos, Cambodia, Vietnam, Malaysia, Indonesia, Philippines, Micronesia, New Guinea, Australia, Polynesia
In open areas, glassland, lawn, marshes, meadows, paddy fields, roadsides, swamps, tropical rain forest and pine-deciduous dipterocarp forests; 0‒1400 m altitudess; flowering and fruiting throughout the year