Description from Flora of China
Subshrubs or herbs. Stems to 30 cm, brown pannose, glabrescent. Leaves opposite, mostly crowded near stem apex; petiole (0.5-)1-10 cm; leaf blade elliptic to obovate, ovate, or oblong, 3-20 X 1.5-10 cm, papery, adaxially densely puberulent to pubescent, abaxially densely rust-brown to gray pannose, base broadly cuneate to cordate, margin densely crenate-serrate, apex acute to rounded; lateral veins 5-10 on each side of midrib. Cymes axillary; peduncle 4-12 cm, rust-brown pannose; bracts 2, ovate to suborbicular, 7-12 X 4-11 mm, outside pannose. Pedicel 5-10 mm. Calyx 5-sect from base; segments narrowly oblong to lanceolate or linear, 3-4 X 0.5-1 mm, outside pannose, glabrescent. Corolla white to purplish, seldom purple-red, 1-1.3 cm, outside glabrous to sparsely glandular puberulent; tube 6-8 mm; adaxial lip ca. 3.5 mm, lobes ca. 3 X 4-5 mm; abaxial lip ca. 6.5 mm, lobes 3-4 X 4-5 mm. Filaments 3-5 mm, glandular puberulent; anthers 3-4 mm; staminodes 2, 1-1.5 mm. Pistil sparsely glandular puberulent to glabrous; ovary ca. 6 mm. Style ca. 4 mm. Capsule spirally twisted, 2.5-5 cm, glabrous. Fl. Jun-Sep, fr. Jun-Oct.
On rocks of limestone hills and valley forests; 200-1500 m. Guangdong, SW Guangxi, S Guizhou, E and S Yunnan [Thailand, N Vietnam].