Description from Flora of China
Gratiola pusilla Willdenow, Sp. Pl. 1: 105. 1797; Lindernia hirta (Chamisso & Schlechtendal) Pennell; L. stellarifolia Hayata; Torenia hirta Chamisso & Schlechtendal; Vandellia hirta (Chamisso & Schlechtendal) T. Yamazaki.
Annuals, 6-30 cm tall, diffuse, sometimes long stoloniferous. Stems suberect, subglabrous or hairy, densely coarsely hairy on nodes, internodes to 6 cm. Leaves short petiolate below, sessile above; leaf blade ovate, cordate, or occasionally orbicular, to 1.2 cm, sparsely with appressed coarse hairs, base cuneate to subcordate, margin subcrenate or entire, veins impressed on adaxial surface. Inflorescences terminal, subumbellate-racemose, 3-5-flowered. Pedicel slender, 0.8-1.5 cm, pilose to subglabrous. Calyx deeply lobed; lobes lanceolate, coarsely hairy outside. Corolla purple, ca. 9 mm; lower lip ca. 5.5 mm, much longer than upper lip; upper lip broadly ovate, emarginate. Filaments of anterior stamens slender, base geniculate. Stigma 2-lamellate. Capsule ovoid-globose, almost as long as persistent calyx. Seeds oblong, tuberculate. Fl. May-Sep, fr. Sep-Nov.
By water, wet places, rice fields, forests; 800-1600 m. Guangxi, Hainan, Taiwan, S Yunnan [Cambodia, India, Indonesia, Laos, Malay-sia, Myanmar, Nepal, New Guinea, Philippines, Sri Lanka, Thailand, Vietnam].