Description from Flora of China
Vandellia oblonga Bentham, Scroph. Ind. 35. 1835; Lindernia subcrenulata (Miquel) Merrill; Torenia oblonga (Bentham) Hance; Vandellia subcrenulata Miquel.
Perennials. Roots fibrous. Rhizomes horizontal. Stems erect or sometimes procumbent and ascending, subquadrangular, glabrous, median internodes to 6 cm. Branches few, ascending. Leaves short petiolate below, sessile and subamplexicaul above; leaf blade rhomboid-ovate to rhomboid-lanceolate, 5-20 X 3-8 mm, base broadly cuneate, margin often with few irregular undulate sinuses or small teeth, or entire, apex subacute to rounded. Racemes lax, usually less than 10-flowered; bracts lanceolate. Pedicel slender, 0.7-2.5 cm. Calyx narrowly campanulate, lobed to 1/4 length; lobes triangular-ovate, glabrous, apex acute and recurved, midrib evident. Corolla purple to purple-blue, to 1.3 cm or more; tube ca. 7 mm; lower lip 3-lobed; upper lip 2-lobed. Stigma broadly lamellate. Capsule ellipsoid, shorter than persistent calyx. Seeds numerous. Fl. May-Jul, fr. Aug-Oct.
Sandy soil; low elevations. Guangdong, Hainan [Cambodia, Laos, Vietnam].