Herbs. Leaves opposite, often linear and glaucous. Flowers terminal, solitary, in loose cymes or in dense involucrate heads. Sepals united to form a tubular calyx; the calyx with numerous parallel obscure veins, bearing 4-10 epicalyx segments. Petals 5, entire, toothed or (in ours) deeply fimbriate; pink, red or white; coronal scales 0. Stamens 10. Styles 2. Fruit a 1-locular capsule with 4 teeth. Seeds flattened.