A large, many-branched shrub to 4 metres in height (though larger, tree-like forms are known). Leaves are small (usually 3-4 centimetres long) and oval-shaped. They are generally smooth but may be hairy underneath. Branches have large spines at intervals. Flowers are creamy-white and produced in clusters at the ends of the branches. They are highly valued by insects. Flowers are followed by purse-like fruits which turn dry at maturity and open at one end, discharging the small, round, flattened seeds.