Description from Flora of China
Annuals, sparsely hirtellous. Stems 17-50 cm, simple or branched at base, creeping or ascending, rooting from lower nodes. Petiole 6-10 mm; leaf blade ovate to narrowly ovate, 2-4 X 1-2.5 cm, base rounded to rarely broadly cuneate, margin coarsely toothed, apex acute to short acuminate. Inflorescences from middle or lower leaf axils, usually dichotomous, sometimes racemose, 2-8-flowered; bracts triangular-subulate to linear, ca. 3 mm, pubescent. Pedicel 5-8 mm, 6-12 mm in fruit, pubescent. Calyx tubular, ca. 1 cm, to 1.2 cm in fruit, 5-winged; wings unequal, 0.5-1 mm wide; lobes 5, narrowly lanceolate, 3-4 mm, apex acuminate. Corolla yellow, rarely white and faintly blue, ca. 1.1 cm. Anterior stamens appendages subclavate, ca. 3 mm. Style apically dilated, 2-lobed, lobes rounded. Capsule ellipsoid, ca. 7 X 3 mm. Fl. and fr. Jul-Oct.
* Dense forests, shady and wet places along trails; below 1000 m. Guangdong, Guangxi, Hainan.