Fls small, perfect, or plants polygamous or dioec. Infl. cymose or reduced to a solitary fl. Calyx a minute ring, teeth obsolete; corolla rotate. tube very short. lobes (3)-4-(5). valvate; stamens 4. exserted; styles 2, connate near base, stigmas capitate. Ovary 2-celled, ovules 1 per cell, disk nectariferous. Fr. mostly dry, of paired 1-seeded cocci, testa adherent to pericarp. Annual to perennial slender herbs with 4-angled stems and lvs and lflike stipules forming whorls of 4-12. Sub-cosmopolitan genus with over 300 spp. The N.Z. spp. endemic Flowering and fruiting season ±11-6.

Annual or perennial herbs with slender, usually 4-angled stems. Lvs and leaflike stipules similar, in whorls of 4-12, mainly sessile or subsessile. Fls small, usually ☿, rarely unisexual, in terminal or axillary panicles or cymes, rarely solitary; ultimate infl. branches with or without bracts; bracteoles 0. Calyx a minute ridge. Corolla (3)-4-(5)-lobed, usually rotate with very short or almost no tube, rarely funnelform. Stamens 4, usually very short. Ovary 2-celled; ovules 1 per cell; styles 2, connate towards base; stigmas capitate. Fr. dry, of 2, 1-seeded mericarps, glabrous or variously hairy, sometimes bristly.