Monoecious or dioecious herbs, covered with stinging hairs. Stem ridged or angular. Leaves petiolate, opposite,
(3-) 5-7-costate, serrate or palmately lobed; stipules free lateral or interpetiolar. Inflorescence of dichasial cymose clusters arranged in axillary unisexual or bisexual racemes, spikes or panicles. Flowers green, minute, unisexual. Calyx of 4, free, imbricate sepals, equal in male but unequal in female flowers. Stamens 4, opposite to sepals, staminodes absent in female flowers. Ovary ovoid. straight; style absent or very short, stigma capitate-penicillate; pistillode cup-like in male flowers. Achene ovoid-elliptic or oblong, compressed, enveloped by larger inner pair of sepals.