Annual or perennial herbs. Leaves opposite, exstipulate. Flowers in loose or dense dichasia, sometimes solitary. Calyx cylindrical, 15-25-nerved, 5-toothed. Petals 5, long-clawed; coronal scales present or 0. Stamens 10. Ovary sessile or borne on a carpophore, 1-celled, many-ovuled, with central placentation; styles 2. Capsule oblong to obovoid, dehiscent by 4 teeth or valves. Seeds reniform or almost globular; embryo peripheral.