Capsule very characteristic, subglobose, splitting in a plane at right angles to the central partition into 2 valves one of which often falls away entirely but the other remains attached to the rhachis by means of a woody pedicel.
Corolla tube filiform to narrowly infundibuliform, lobes 4–6(7), deltoid to lanceolate, suberect; throat practically glabrous except for an obscure ring of hairs some distance below the orifice.
Calyx tube ovoid or urceolate, often bristly hairy; limb-tube absent; lobes 5–6, equal or unequal, spathulate, filiform or lanceolate with small glands between each pair.
Ovary bilocular; ovules attached to placentas which are affixed to the septum; style much exserted, often overtopping the corolla lobes; stigma subcapitate.
Annual or perennial herbs or subshrubby herbs with erect or procumbent glabrescent to stiffly hairy stems from a fibrous rootstock.
Flowers small, hermaphrodite, never dimorphic, in few-to many-flowered cymose clusters at the apices of the main shoots.
Stipules small, limbs free, entire, deltoid, or fimbriated with linear setae from a short base.
Seeds small, brownish, subglobose, reticulately pitted.
Disk cylindrical or consisting of two separate cones.
Stamens 4–6, much exserted.
Leaves paired.