Fls hermaphrodite, regular, solitary or in cymes. Sepals 4-5, free; petals white, 4-5, us. very deeply bifid, sts lacking; stamens 10 or fewer; ovary 1-celled, styles 3 (rarely 2 or 4-5), free to the base; capsule opening by twice as many teeth as there are styles. Slender annual to perennial herbs. Lvs opp., simple, entire, exstipulate. About 85 spp., cosmopolitan. The 6 spp. indigenous to N.Z. are all endemic. Several naturalized spp. are widespread weeds.

Annual or perennial herbs. Hairs usually sparse and eglandular, or 0. Lvs opposite, exstipulate, sessile or petiolate, glabrous or ciliate, linear, lanceolate, ovate or orbicular. Infl. a dichasium or reduced to 1-2 fls; bracts scarious to herbaceous; epicalyx 0. Sepals 5, free, not veined or (1)-3-veined. Petals white, divided almost to base, rarely 0. Stamens 10 or fewer. Styles 3. Fr. a capsule, usually ovoid, sometimes globose or cylindric, dehiscing by 6 teeth; carpophore 0. Seeds usually 4-10, ovoid, flattened, tuberculate or papillate, not winged.