Herbs or shrubs, with cystoliths. Leaves sessile or petiolate; leaf blade margin entire or subentire [or lobed]. Flowers in axillary or terminal thyrses, racemes, or spikes; bracts and bracteoles present, mostly shorter than calyx. Calyx deeply 5-lobed; lobes equal to subequal. Corolla salverform; tube slender, not or scarcely apically enlarged; limb 5-lobed or 2-liped; lobes ± equal or 3 of lower lip slightly larger than 2 of upper lip, ascending cochlear in bud. Stamens 2, included in corolla tube or exserted from corolla mouth (some species heterostylous); anthers 2-thecous; thecae equal to subequal, parallel, inserted at same height, muticous; staminodes 2 or absent. Style included or exserted; stigma 2-lobed, lobes equal. Capsule clavate with a long solid stalk, 4-seeded; retinacula present. Seeds lenticular, ornamented or smooth, lacking trichomes.

About 50 species: pantropical; seven species (two endemic) in China.

(Authors: Hu Jiaqi (胡嘉琪 Hu Chia-chi), Deng Yunfei (邓云飞); Thomas F. Daniel)