The koa (Acacia koa; Family Fabaceae) is a large tree endemic to the Hawaiian Islands, primarily Hawaiʻi, Maui and Oahu.
The koa tree is somewhat unusual in that the leaves produced early in the growth of the plant are compound leaves typical of the pea family. However, the adult koa has thick sickle-shaped "leaves" that are not compound. These are phyllodes, blades that develop as an expansion of the leaf petiole. The vertically flattened orientation of the phyllodes allows sunlight to pass to lower levels of the tree.
