Dwarf annuals or perennials, often tufted. Leaves opposite, subulate, connate at base, exstipulate, the basal forming a rosette. Flowering shoots slender, prostrate or ascending. Flowers in dichasial cymes or solitary and terminal, usually on long pedicels. Sepals 4-5, free. Petals 4-5, entire or notched, sometimes O. Stamens 4-10. Ovary 1-celled, many-ovuled; styles 4-5, alternating with sepals. Capsule dehiscent to base into 4-5 valves. Seeds minute, reniform.