The Madras Thorn is a medium-sized tree that can grow up to 15 m in height. The crown is spreading, relatively low, and bushy in appearance. Its leaves are held in pairs of tiny leaflets on either side of the leaf stalk, but their beauty is tempered by the sharp thorns that lie at their bases. The white flowers of the Madras Thorn are tiny, have numerous conspicuous stamens and are borne in heads of 10 to 20 on stalks that reach 30 cm or more in length. Its fruit is a coiled pod which ripens with a tinge of rose-red, and splits open to expose thick white pulp surrounding shiny black seeds that seem to hang out on short, rose-red ‘strings’. The pulp is edible, attracting birds like the Yellow-vented Bulbul (Pycnonotus goiavier) and the Oriental Magpie Robin (Copsychus saularis), which help to disperse its seeds.

A native of tropical America, the Madras Thorn was introduced to this region by the Portuguese and Spanish. This species is useful in many ways — its leaves and pods serve as fodder; its wood can be used in rough construction or as firewood; its bark yields gum and tannin; and its pulp can be eaten or made into a juice. The name of its genus, Pithecellobium, comes from the Greek words pithekos, meaning ‘ape’, and lobos, which refers to a pod or a lobe. Its specific epithet, dulce, means ‘sweet’.

The Madras Thorn was once a commonly planted roadside tree in Singapore, but suffered from caterpillar attacks in Singapore during the 1970s. The species was subsequently phased out from planting in housing estates and along roadsides.