Description from Flora of China
Shrubs or perennial herbs. Leaves opposite; leaf blade margin entire. Inflorescence axillary or terminal, branched cymes; bracts narrow to subleaflike; bracteoles inconspicuous or absent. Calyx often gland-tipped hairy, deeply 5-lobed; lobes equal or subequal. Corolla purple or yellow, funnel-shaped to campanulate; tube ventricose; limb 5-lobed; lobes subequal, contorted in bud. Stamens 4, didynamous; filaments connate at base into 2 pairs; anthers 2-thecous; thecae parallel, hirsute, spurred at base. Ovary with 4-8 ovules per locule; stigma 2-lobed, one lobe reduced. Capsule linear-cylindric to linear-oblong, 8-16-seeded; retinacula present. Seeds subovate in outline, compressed, covered with hygroscopic trichomes.
Four species: Bhutan, China, India, Nepal, Vietnam; three species (two endemic) in China.
(Authors: Hu Jiaqi (胡嘉琪 Hu Chia-chi), Deng Yunfei (邓云飞); Thomas F. Daniel)