Corolla regular with a cylindric tube and with 4 lobes about as long as the tube, without nectaries.
Ovary cylindric-ovoid, unilocular; ovules numerous; style filiform; stigma bilobed.
Leaves sessile, the upper ones much reduced and scale-like.
Flowers 4-merous in compact, pedunculate, terminal heads.
Stamens 4, unequal, 3 sterile, 1 larger, fertile.
Stems not or sparsely branched from the base.
Capsule narrowly-obovoid, bivalved.
Calyx tube as long as the lobes.
Seeds numerous, subglobose.
Erect perennial herbs.