Annual or perennial herbs. Stems often decumbent or ascending. Leaves opposite, linear to filiform; stipules scarious. Flowers hermaphrodite, rarely unisexual, in cymose inflorescences. Sepals 5, free, with scarious margins. Petals 5, white or pink, entire. Stamens (2)5-10, inserted on a perigynous ring. Ovary 1-celled, many-ovuled; styles 3 (-5). Fruiting pedicels reflexed. Capsule 3 (-5)-valved. Seeds subspherical to almost lenticular-reniform, winged or wingless.