Subshrubs, often twining or climbing, monoecious; indumentum usually with simple and stinging hairs. Leaves alternate; stipules conspicuous, persistent; leaf blade entire or 3-5-lobed or 3-5-partite, base usually stipellate; basal veins 3-7. Inflorescence axillary, long peduncled, capitate, bisexual, enclosed between 2 subopposite, often showy, involucral bracts; lower bract subtending a cyme of female flowers in a contracted cyme subtended by a lower bract and 1 or 2 fused upper bractlets, male inflorescence terminal but apparently inserted between female cymule and upper involucral bract, 3- or 8-12-flowered, surrounded by involucel of bracts; bracteoles of male flowers all or partly producing resin. Male flowers pedicellate; sepals 4 or 5(or 6), valvate, recurved at anthesis; petals absent; disk absent; stamens (8-)10-30(-100); filaments connate; anthers 2-locular, parallel; pistillode absent. Female flowers subsessile; sepals 5-12, imbricate, usually pinnatifid, accrescent; ovary 3-locular; styles connate in a column; stigma often lobed or discoid. Fruit a capsule, 3-locular, enclosed by accrescent calyx, often setose. Seeds globose, with or without caruncle.

About 120 species: chiefly in tropical regions of the Americas, also in tropical Africa and S and SE Asia; one species in China.

(Authors: Qiu Huaxing (丘华兴 Chiu Hua-hsing, Kiu Hua-shing, Kiu Hua-xing); Michael G. Gilbert)