Annual or perennial small glabrous herbs, often prostrate. Leaves opposite or in whorls of 4, usually oblong or obovate, stipulate; stipules scarious, silvery, sometimes with a green stripe in the middle. Cymes dichasial, many-flowered. Bracts scarious or with a green stripe. Flowers small. Sepals 5, free, keeled, hooded, narrowly scarious-margined. Petals 5, clawed, small, oblong to obovate, entire or emarginated to obcordate. Stamens 3-5, inserted on a perigynous disk. Ovary 1-celled, many-ovuled; style short, 3-fid. Capsule 3-valved. Seeds many or few, with convex back.