The deciduous wiliwili is endemic to the Hawaiian Islands. It's a member of the bean family, and is an important part of the Hawaiian ecosystem. Wiliwili trees provide food and shelter for a variety of birds and insects and has many traditional cultural uses. It is typically found in dry forests on leeward island slopes up to an elevation of 2,000 feet.

The wiliwili tree can grow to a height of 15–30 feet with a gnarled and stout trunk that reaches 1–3 feet in diameter. The bark is smooth and covered in small gray or black spines up to 1 cm in length. The leaves are trifoliate, with each leaflet being up to 3 inches long. The flowers bloom in showy clusters that are 3–5 inches in diameter. They can be yellow, orange, salmon, pastel green, or white. The fruit is a woody pod that contains 1–3 red or orange seeds.