Small shrubs or suffrutices. Leaves opposite. Flowers usually in cymes, or solitary and axillary, or in terminal spikes or heads with reduced leaves; bracts and bracteoles sometimes spiny. Calyx 4-partite; segments unequal, leaf-like or membranous, sometimes spiny, the two outer enclosing the inner. Corolla ± actinomorphic, 4-5-lobed or ± 2-lipped, with a tubular base; lobes obovate, sometimes unequal. Stamens 2 or 4, not didynamous. Ovary 2-locular with 2 ovules per loculus. Capsule solid in upper part; seeds flat with hygroscopic hairs.