Acacia koa Acacia koa Acacia koa is a species of flowering tree in the pea family, Fabaceae. It is endemic to the Hawaiian Islands, where it is the second most common tree. The highest populations are on Hawaii, Maui and Oahu. Its name in the Hawaiian language, koa, also means brave, bold, fearless, or warrior. Koa is a large tree, typically attaining a height of and a spread of . In deep volcanic ash, a koa tree can reach a height of , a circumference of , and a spread of . It is one of the fastest-growing Hawaiian trees, capable of
Hakalau Forest National Wildlife Refuge numerous deep gulches. Rainfall decreases to about at elevations above , where majestic koa ("Acacia koa") and red-blossomed ōhia lehua ("Metrosideros polymorpha") trees form a closed-canopy forest. Further upslope, above , rainfall decreases to or less and native forest merges into abandoned pastureland where alien grasses and weeds, introduced as forage for cattle, are the dominant vegetation. Since 1989, over 400,000 koa, ōhia, and other native plants have been planted in this area as part of the refuge's reforestation program. The Pua Akala Cabin, located within the refuge, was nominated to the National Register of Historic Places in August 2008.