Description from Flora of China
Trees small, shrubs, subshrubs, or perennial herbs, without stinging hairs. Leaves alternate or opposite; stipules deciduous, intrapetiolar, free or rarely connate at base; leaf blade 3-veined, margin dentate, rarely 2- or 3-lobed; cystoliths punctiform. Inflorescence an axillary glomerule, on normal leafy stems or on specialized, slender, mostly axillary, occasionally terminal, shoots, these unbranched and spikelike to branched and panicle-like, mostly unisexual, less often bisexual. Flowers unisexual (plants monoecious or dioecious); bracts and bracteoles small, scarious. Male flowers: perianth (3 or)4 or 5-lobed or parted, segments valvate; stamens (3 or)4 or 5; filaments inflexed in bud; rudimentary ovary clavate or subglobose. Female flowers: perianth tubular, usually compressed, apex 2-4-toothed, in fruit sometimes enlarged and dilated into 2 acute angles or wings; staminodes absent. Ovary included; stigma filiform, on a style, pilose on 1 side, usually persistent for some time; ovule orthotropous. Achene not lustrous, enclosed by marcescent perianth, Seed with endosperm; cotyledons elliptic or ovate.
About 65 species: tropical, subtropical, and rarely temperate regions; 25 species (six endemic) in China.
(Authors: Chen Jiarui (陈家瑞 Chen Chia-jui); Ib Friis, C. Melanie Wilmot-Dear)