Suberect, rambling, twining or scandent herbs or suffrutices. Leaves ovate to lanceolate, sometimes cordate or hastate. Inflorescence terminal, compound monochasial cymes or thyrses or of solitary, axillary flowers with long pedicels; bracts 2, large, elliptic or ovate, surrounding each flower and hiding calyx. Calyx regular, usually with a shallow tube with 10-18 linear teeth or rarely shallowly cupular with 5 broad lobes. Corolla regular or subregular; lobes 5, obovate, spreading, contorted in bud; tube much longer than lobes, usually cylindric at base, funnel-shaped above. Androecium: fertile stamens 4, didynamous (arising in pairs) or subdidynamous; arising in lower part of corolla tube, included; filaments broadly linear; anthers 2-thecous; thecae parallel, each apiculate or with 1 apiculus and 2-spurred at base, with connective usually produced into an appendage, ciliate, or covered with multicellular hairs, which are sometimes club-shaped; staminodes 0. Pollen spheroidal; 3-colpate, surface foveolate, pusticulate or spinose. Disc deeply cupular. Gynoecium: ovary with 2 ovules in each locule; style terete, included; stigma funnel-shaped, with 2 infolding lobes and a tuft of hairs on each lobe and with stalked glands or stigma of 2 unequal lobes, one above the other. Fruit a globose capsule, abruptly rostrate, estipitate, with inelastic placental bases; retinacula 0. Seeds thick, broadly elliptic, with a cavity or groove on one face and convex on the other; surface rugose and sometimes tuberculate. x = 8, 9 (7, 10) (high polyploidy).
Species +/- 100, Old World tropics; 11 in sthn Afr., Namibia, Botswana, Swaziland and northern and eastern provinces of South Africa.