Annual or perennial, polygamous herbs, often with uncinate hairs. Leaves 3-costate, exstipulate, alternate, entire. Inflorescence of 3-many flowered-small, axillary, bracteate cymes or in involucrate clusters with intermixed bisexual and unisexual flowers or only bisexual flowers. Calyx deeply (3-)4-lobed in male and hermaphrodite flowers; tubular and shallowly lobed in female flowers. Stamens as many as calyx lobes. Ovary free from calyx, ovule orthotropous, basal; style present or absent, stigma desely penicillate deciduous; pistillode globose in male flowers. Achene compressed, ovate, enveloped by calyx.