Mostly herbs or undershrubs, with or without stinging hairs. Leaves simple, stipulate, rarely exstipulate, alternate or opposite, often with dot-like or linear cystoliths. Inflorescence axillary, cymose or fasciculate, rarely flowers solitary. Flowers minute, usually greenish, unisexual (Plants monoecious or dioecious), actinomorphic, hypogynous. Calyx (3-) 4-5-lobed, often enlarged in fruit, rarely absent in female flowers; lobes equal or unequal, imbricate or valvate, rarely sepals free. Petals absent. Stamens (3-) 4-5, rarely solitary, antisepalous, generally inflexed in bud; anthers dithecous, dehiscence longitudinal; staminodes scaly or absent in female flowers. Ovary monocarpellary, free or rarely adnate to calyx, unilocular, uniovulate, ovule orthotropous, erect or ascending, pseudobasal, rarely apical; style simple, stigma capitate and mostly penicillate; pistillode present in male flowers. Fruit a monospermous achene or fleshy drupe, more or less enveloped by persistent membranous calyx. Seed albuminous, embryo straight.