Small trees or perennial herbs or climbers. Leaves simple, opposite, entire or nearly so; stipules absent. Flowers irregular, bisexual. Sepals 5 and almost free or calyx tubular, 5–15-lobed. Corolla tubular, sometimes 2-lipped, 4 or 5-lobed. Stamens 2–4, epipetalous. Ovary superior, 2-locular; placentas axile or free central. Fruit a loculicidal capsule, 2-valved. Seeds flat, attached to hooked processes from the septum; or solitary, without integuments, the embryo with 2 large cotyledons folded longitudinally. 250 gen., mostly trop.