Herbs, usually glandular hairy. Stems erect or reclining, branched. Leaves petiolate, simple, entire. Flowers solitary, axillary, somewhat actinomorphic. Calyx tubular-campanulate, deeply 5-parted. Corolla funnelform or salverform, tube gradually inflated upwards; lobes short, rounded or short pointed. Stamens inserted in corolla tube, included; filaments slender; anthers dehiscing longitudinally; disc glandular, entire or lobed. Ovary 2-locular; stigma indistinctly 2-lobed; ovules numerous. Fruit a dry, 2-valved capsule. Seeds minute, subglobose or ovoid, reticulate-pitted; embryo slightly curved or erect.

About three species: South America, one cultivated in China.