Description from Flora of China
Herbs, annual, biennial, or perennial, rarely monocarpic. Roots fusiform or attenuate, simple. Stems 1 or more, erect or ascending, terete, branched or not, very constricted or extended, usually setose, rarely glabrous, ivory malodorous lactiferous, with leaves or not. Basal leaves petiolate, usually glaucous adaxially, variously shaped, both surfaces setose, pinnatilobate, pinnatipartite, pinnatisect, or bipinnatifid, sometimes incised, serrate, or crenate, rarely entire. Cauline leaves if present, similar to basal leaves, but usually sessile, sometimes amplexicaul. Flowers solitary, rarely in cymose racemes, pedunculate or sometimes scapose, erect, extended, usually setose. Flower buds nutant, ovoid or spherical. Sepals 2, rarely 3, shedding as flowers open, mostly setose. Petals 4, rarely 5 or 6, on short receptacles, often caducous, mostly red, rarely white, yellow, orange, or lavender, vivid and beautiful, usually obovate, in 2 whorls, outer whorl larger. Stamens many; filaments white, yellow, green, purple, or red, occasionally blackish, mostly filamentous; anthers spheroidal or oblong. Ovary 1-loculed, superior, usually ovoid, rarely terete-oblong; carpels 4-18, united, setose or glabrous; ovules many, astylous; stigmas 4-18, actinomorphic, united into compressed or steepled disk covering ovary; disk margin crenate or divided. Capsule narrowly terete, obovoid, or spherical, setose or glabrous, rarely spiny, obviously costate or not costate, poricidal under actinomorphic stigmas. Seeds many, black, brown, dark gray, or white, reniform, small, longitudinally striate or alveolate; albumen white, fleshy and rich in oil; embryo hidden in albumen.
About 100 species: mainly in C and S Europe to temperate Asia, some in the Americas and Oceania, one in South Africa; seven species (three cultivated) in China.
(Authors: Zhang Mingli (张明理); Christopher Grey-Wilson)