Description from Flora of China
Herbs, perennial. Roots usually thickened, various in shape, carrot-shaped, mostly fleshy. Caudexes often short, sometimes elongated and branched. Stems erect, less frequently ascending. Basal leaves often rosulate, usually long petiolate, cordate; cauline leaves mostly alternate, rarely opposite or verticillate. Flowers in a cyme; cymes sometimes reduced to a branch with 1 terminal flower and 1 to several bracts, sometimes glomerate into a panicle. Calyx epigynous, rarely semi-epigynous, tube various in shape; lobes 5, entire or dentate. Corolla always epigynous, campanulate, funnelform, or tubular, 5-lobed or 5-fid to middle. Stamens 5; filaments much dilated into a lamella at base; lamellae densely ciliate-villous, valvate, enveloping disk; anthers elongate. Disk usually tubular, rarely annular. Ovary inferior, 3-locular; ovules numerous; style with pollen-receiving hairs; stigma 3-lobed, lobes narrow, recurved. Capsule 3-poricidal below persistent calyx lobes. Seeds numerous, ellipsoid, 1-angular.
Sixty-two species: E Asia, south to India and Vietnam, with one species extending into Europe and another endemic to Crimea; 38 species (23 endemic) in China.
(Authors: Hong Deyuan (洪德元), Ge Song (葛颂); Thomas G. Lammers, Laura L. Klein)