Trees or shrubs. Leaves alternate, bipinnate or modified to phyllodes, often bearing one or more nectaries (glands) on the petiole or leaf-rhachis, with or without stipules. Flowers regular, usually bisexual, in spikes racemes or heads, usually small. Calyx tubular; lobes 4–5, valvate. Petals free or connate basally, 4–5, valvate. Stamens usually numerous, free or connate into a tube, hypogynous or perigynous. Ovary superior, 1-locular; placenta marginal. Fruit a legume. Seeds often with an aril which may be brightly coloured. 60 gen., trop to warm temp., particularly S. Africa and Aust.