Description from Flora of China
Herbs, perennial, epiphytic, epipetric, or terrestrial, rhizomatous. Stems simple or branched. Leaves few, spread along stem, rarely crowded near apex, opposite, unequal or subequal, rarely equal in a pair; leaf blade glabrous to pubescent or strigose, base cuneate to subcordate. Inflorescences lax, often dichotomously branched, axillary, 1- to many-flowered cymes; bracts 2, opposite. Calyx actinomorphic, 5-sect from base or near base; segments equal. Corolla white, yellowish, purple, or pinkish, often spotted within, zygomorphic, inside glabrous to subglabrous; tube broadly tubular, gibbous abaxially, 2-4 X longer than limb, 1-2 cm in diam.; limb 2-lipped; adaxial lip 2-lobed; at least slightly shorter than abaxial lip; abaxial lip 3-lobed, lobes equal or central lobe longer, apex rounded to obtuse. Stamens 4, adnate to corolla tube near base or near middle, included; anthers basifixed, coherent in pairs at apex, thecae subparallel, confluent or not at apex, dehiscing longitudinally; connective not projecting; staminode 1 or absent, adnate to adaxial side of corolla tube. Disc ringlike. Ovary oblong to linear, 1-loculed; placentas 2, parietal, projecting inward, 2-cleft. Stigmas 2, equal, oblong to suborbicular, undivided. Capsule straight in relation to pedicel, narrowly oblong to linear, much longer than calyx, dehiscing loculicidally to base; valves 2, straight, not twisted. Seeds (when known) with 1 hairlike appendage at each end.
Seven species: Bhutan, China, India, Myanmar, Nepal, Sikkim, N Vietnam; all seven species in China.