Wiliwili (Erythrina sandwicensis) is a species of tree in the pea family, Fabaceae, that is endemic to the Hawaiian Islands.

It is typically found in Hawaiian tropical dry forests on leeward island slopes up to an elevation of 600 m (2,000 ft).

The bark on the main trunk of mature trees has a distinct orange cast,[2] which is caused by a terrestrial alga.

The dry season usually begins in late April or in May, and trees in the wild typically lose all of their leaves before they bloom.

That the wiliwili bears spines is unusual for a species that has evolved in the isolated Hawaiian Islands, without the presence of ungulates or other large herbivores.

The wiliwili is thought to be closely related to E. tahitensis, a tree endemic to the Tahitian Archipelago, and E. velutina, a widespread species found in tropical South America and the Caribbean.

[8] Seven other species of Erythrina were under general cultivation in the Hawaiian Islands, but have been mostly extirpated by the alien gall wasp (see Conservation, below).

[17] It is thought to have originated in Africa, and the means of its rapid dispersal across South Asia, the Pacific, and southern North America is not understood.

[19] A parasitoid wasp, Eurytoma erythrinae, was released by the Hawaiʻi Department of Agriculture in December 2008 as a biocontrol to minimize the damaging effects of Quadrastichus.

The Hawaii Departments of Agriculture and of Land & Natural Resources therefore plan to introduce a second parasitoid wasp from Africa, Aprostocetus nitens.

In 1786, in his book Encyclopédie Méthodique: Botanique, Jean-Baptiste Lamarck originated the name Erythrina monosperma for a Leguminous tree from India and Southeast Asia.

[24] In 1841, William Jackson Hooker and George Arnott used Gaudichaud's name in their book, The Botany of Captain Beechey's Voyage.