Description from Flora of China
Herbs perennial, glabrous or hairy. Roots fibrous or tuberous, often carrot-shaped. Rhizome short, fleshy or woody; young branches not covered with scales. Flowering stem arising from lateral bud of previous year, annual and abscissing from base or persisting and basally woody. Stem leaves alternate, opposite, or 3-5-verticillate; leaf blade flat, glabrous, spurless. Inflorescence terminal, sometimes also subterminal and thus paniculate, cymose, often corymbiform, sometimes umbel-like, many flowered, bracteate. Flowers bisexual or unisexual, unequally (4 or)5-merous, sometimes reduced. Sepals usually shorter than petals, base subconnate and spurless. Petals usually free, purple, red, pink, or white, occasionally yellowish or greenish. Stamens 2 × as many as petals, inserted basally on corolla. Nectar scales oblong-cuneate to linear-oblong, apex rounded or subemarginate. Carpels free, base narrow, substipitate. Follicles erect, many seeded. Seeds narrowly winged.
About 33 species: Asia, Europe, North America; 16 species (six endemic) in China.