Description from Flora of China
Herbs, biennial or perennial, sometimes subshrubs due to lignification at base, rarely annual. Leaves opposite; cauline leaves amplexicaul; leaf blade pinnatipartite or pinnatisect, rarely entire. Capitula terminal, oblate-globose, ovoid, or ovoid-conical, long pedunculate; involucral bracts leaflike, in 1 or 2 series; receptacles conical to semiglobose, sometimes columnar; bracts linear-lanceolate, 1-veined, back often carinate; involucel (epicalyx) 1, broadly funnelform or angular-columnar, 8-ribbed in fruit, furrowed in entire length, or furrowed only above and rounded at base, often fissured into 2-8 pits apically, top becoming a membranous, campanulate or rotate crown, 16-30-veined, margin dentate. Calyx stalked, disklike, 5-segmented into radial setae. Corolla usually dimorphic, tubular, blue, purple, purple-red, yellow, or white, 4- or 5-lobed; that of marginal ray flowers usually larger, 2-lipped; upper lip usually 2-lobed, shorter; lower lip 3-lobed, elongated and raylike; that of central flowers usually tubular; lobes subequal in length. Stamens 4, exserted. Ovary enveloped in involucels; style slender; stigma peltate or capitate. Achenes enveloped in involucels, crowned with persistent setose calyx. Seeds with a large, straight embryo and scanty endosperm.
About 100 species: S and W Africa, Asia, Europe, mainly in the Mediterranean; six species (one endemic) in China.