Herbs annual or perennial, rarely subshrubs, covered with vesicular or terete hairs (in several species sometimes also with uniseriate, multicellular hairs), farinose (“mealy”) when dry, rarely glabrous. Leaves alternate, petiolate; leaf blade complanate, margin entire or irregularly serrate or lobed. Inflorescence usually of several flowers forming a glomerule (rarely solitary flowers), these arranged in axillary or terminal spikes, panicles, or dichasia; bracts and bractlets absent. Flowers bisexual or some female. Perianth green, globose, 5-parted, in some species (2 or)3- or 4-parted; segments abaxially slightly fleshy at center or longitudinally keeled, adaxially concave, remaining unchanged in fruit, rarely enlarged or becoming juicy, without appendages. Disk usually absent. Stamens 5 or fewer; filaments sometimes basally united, filiform or capillary; anthers oblong, without an appendage. Ovary globose, slightly depressed, rarely ovoid; ovule subsessile; style obscure or very short; stigmas 2(-5). Fruit a utricle; pericarp membranous or slightly fleshy, adnate to seed or free, indehiscent. Seed horizontal, in some species oblique and/or vertical, ovoid, lenticular, or depressed globose; testa lustrous, leathery, smooth or pitted; embryo annular, semi-annular, or horseshoe-shaped; perisperm copious, farinaceous.

About 170 species: almost worldwide, but most abundant in temperate and subtropical zones; 15 species (one introduced) in China.