Erect, sometimes climbing, shrubs or (less often) herbs or trees. Stems prickly or unarmed. Leaves opposite or in whorls of 3(-4), aromatic, toothed, usually glandular-punctate. Flowers sessile in often colourful, usually axillary, pedunculate heads or spike-like inflorescences; each flower subtended by an ovate to lanceolate acuminate bract. Calyx small, membranous. Corolla very variable in colour, red, yellow, purple, blue, mauve or white, sometimes bicoloured with throat yellow to orange, often changing colour after fertilisation, salver-shaped with narrowly cylindric tube; limb obscurely 2-lipped, 4-5-lobed. Stamens 4. Ovary 2-locular. Fruit a fleshy drupe.