Annual herbs or small shrubs. Leaves alternate, sessile, entire, flat or semi-terete, linear to ovoid. Flowers frequently hermaphrodite or pistillate, axillary and terminal, without bracteoles, frequently forming spike-like inflorescences. Perianth urceolate, 5-lobed, hairy or glabrous. Stamens (3-)5; anthers oblong. Style divided into 2(-3) filiform stigmas. Fruiting perianth with connivent lobes, mostly furnished with prickles, tubercles or wings. Fruit depressed, with membranous pericarp adherent to the seed-coat. Seeds with horizontal or vertical embryo.