Description from Flora of China
Herbs, rarely subshrubs, annual or perennial, erect or procumbent, hairs with swollen base, stellate or with 1 ray and apparently simple. Leaves alternate, simple or palmately 3-5-lobed, palmately veined, margin serrate. Flowers solitary or arranged in small cymes or fascicles, axillary, opposite to leaves, bisexual; peduncle very short. Sepals 5, free, valvate, usually with hooked appendages at tip. Petals as many as sepals, free, thickened glands on base of adaxial surface. Stamens 5 to numerous; filaments free; anthers dorsifixed, subglobose, dehiscence longitudinal, borne on androgynophore; androgynophore fleshy, segmented, short, with 5 glands opposite to petals. Ovary 2-5-loculed; ovules 2 per locule; style simple; stigma 2-5-lobed. Fruit a capsule nearly globose, 3-6-valved, spiny or strigose, loculicidally dehiscent or indehiscent, spine tips pointed, straight or hooked. Seeds with endosperm; cotyledons fleshy, epigeous.
Between 100 to 160 species: primarily in tropical and subtropical areas, several species are widespread weeds; seven species in China.