Wiliwili is one of the more interesting native trees unique (endemic) to the Hawaiian Islands and once widespread across the drier lowlands of all the Islands. The species descriptor, sandwicensis, derives from the old English name for these islands: the Sandwich Isles, named after the 4th Earl of Sandwich by Captain James Cook in 1778. Many of the trees bear spines (technically, these are prickles) on their stems and trunk, although some trees may lack these.

The flowers are quite variable in color, most typically orange or salmon, but on some trees pale green, white, or yellow. Flowering typically occurs when these deciduous trees are barren of their leaves, occuring (again typically, but not necessarily) in the summer dry season. Bean pods that develop late in the dry season contain several bright red seeds.

The wood is soft and light, so was and still is used for canoe outriggers, as well as floats and surfboards. The bright red seeds were strung on leis.