Description from Flora of China
Stems 20-50 cm, spreading rust-brown pubescent. Leaves opposite or in whorls of 3; petiole 1.5-2 mm; leaf blade narrowly elliptic to obovate, 1-2.1 X 0.6-1.1 cm, papery, adaxially nearly glabrous, drying wrinkled, abaxially rust-brown pubescent, not punctate, base cuneate to rounded, margin often 1- or 2-denticulate near apex, apex acute to nearly rounded; lateral veins invisible. Cymes axillary, 1-flowered; bracts deciduous. Pedicel ca. 3 mm, puberulent. Calyx green, deeply 5-lobed; lobes triangular-lanceolate, ca. 4-5 X ca. 1 mm, outside densely puberulent. Corolla yellow or white, ca. 3.4 cm, outside puberulent, inside glabrous, mouth not oblique; limb distinctly 2-lipped; adaxial lip ca. 7 mm; abaxial lip ca. 9 mm, 3-lobed from slightly below middle. Stamens included; filaments 0.8-1.2 cm; anthers of 4 stamens coherent at apex, ca. 3 mm; staminode ca. 5 mm. Pistil ca. 1.7 cm; ovary glabrous. Style ca. 3 mm, glabrous. Capsule ca. 8 cm. Seeds with 1 hairlike appendage at each end, appendages 5-8 mm. Fl. Feb, fr. Oct.
On trees in dense forests; 1200-1500 m. SE Yunnan [Laos, N Vietnam].