Erect shrubs or herbs with terete or ± quadrangular slightly 4-winged twigs. Leaves thick-coriaceous, opposite or sometimes pseudo-alternate, the members of a pair occasionally unlike, entire, crenate or toothed, acute to short acuminate. Flowers white, purplish pink or blue and white, solitary or in axillary and or terminal, lax or condensed, interrupted spikes or panicles or capitate, heads; bracts solitary, foliaceous or small, persistent or caducous; bracteoles 2, small or absent. Calyx deeply 5-lobed, lobes equal or unequal, valvate, Corolla campanulate, tube cylindric below, straight or curved, ventricose above, limb subequally 5-lobed, lobes twisted in bud, patent or reflexed. Stamens usually 4, didynamous and basally monadelphous, included or exserted, some¬times, 2, equal, included, 2 staminodes occasionally present; anther cells parallel, free muticous, glabrous or bearded at one end. Ovary oblong-globular, bilocular, 4-8-ovuled; style filiform, stigma with one obsolete lobe. Capsule oblong, apically pubescent or glabrous, 4-8-seeded, retinacula strong, curved. Seeds glabrous or appressed hairy, much compressed.