Fls in simple to compound cymes, or solitary; us. perfect, hypog. or perig.; sepals 4-5, free or joined below; petals as many as sepals, often small or absent, free, often bifid or emarginate; stamens up to 10, anthers dehiscing longitudinally; ovary one-celled, at least in upper part, ovules 1-∞ on basal or free-central placenta, embryo us. curved; fr. us. a dry capsule opening by teeth or valves. Annual to perennial herbs; lvs us. simple, entire, opp., often connate, or with scarious stipules. About 80 genera and 1400 spp. Cosmopolitan, with most spp. in temperate regions.

Fls small, us. with scarious bracts, us. perfect, regular; calyx 4-5-lobed; petals 0; stamens as many as and opp. calyx-lobes; anther-filaments free or connate at base. Ovary 1-celled, ovules 1-(2), styles 1-2-3. Fr. an utricle, ind., nutlike, covered by persistent calyx. Mostly herbs with entire, opp., simple lvs with scarious stipules. About 8 widespread genera and 90 spp.

Annual to perennial herbs, rarely small shrubs. Hairs simple, glandular or eglandular. Lvs opposite, rarely alternate or whorled, stipulate or exstipulate, simple, entire. Infl. usually terminal, typically a bracteate dichasium, sometimes a panicle or reduced to a monochasium or fls solitary. Fls hypogynous, very rarely perigynous, usually ☿, actinomorphic. Sepals (4)-5, free or united; commissures when present green or scarious, veined or not veined. Petals (4)-5 or 0, free, clawed or not clawed, either entire, toothed, emarginate or 2-fid. Stamens 0-10, usually twice as many as sepals. Ovary of 2-5 fused carpels, 1-celled at least above; placentation free-central or basal. Stigmas (1)-2-5, free. Fr. a capsule, usually many-seeded and dehiscing by as many or twice as many teeth as the styles, rarely indehiscent, rarely 1-seeded or a berry. Seeds variously shaped, usually sculptured, often papillate; embryo curved around perisperm, rarely straight.