Trees or shrubs, unarmed or with woody spines. Leaves opposite, simple, entire, dentate or lobed. Calyx often coloured; limb rotate, 5-lobed, very accrescent and becoming papery with raised reticulation in fruit. Corolla strongly zygomorphic, appearing 1-lipped, the lip 5-lobed. Stamens 4, didynamous, long-exserted. Ovary hairy. Fruit dry, hard, turbinate or obconical, sometimes strongly 4-lobed above, separating at maturity into 4 mericarps.