Acacia koa for up to 25 years. Scarification is needed before "A. koa" seeds will germinate. Koa is endemic to the islands of Hawaii, Molokai, Maui, Lānai, Oahu, and Kauai, where it grows at elevations of . It requires of annual rainfall. Acidic to neutral soils (pH of 4-7.4) that are either an Inceptisol derived from volcanic ash or a well-drained histosol are preferred. Its ability to fix nitrogen allows it to grow in very young volcanic soils. Koa and ōhia lehua ("Metrosideros polymorpha") dominate the canopy of mixed mesic forests. It is also common in wet forests. The koa's trunk was
Koa people their territory. In 1998 grazier Noel Kennedy applied to the Federal Court to have his property Castle Hill declared to be free of native title. This was challenged by the descendants of the Koa the following year, in a counterclaim for native title to the Castle Hill Pastoral Holding and the Bladensburg National Park in the Shire of Winton. In mid-2002 a Federal Court declared that the Koa claim did not apply to Kennedy's pastoral lands because the Koa could not demonstrate continuity of cultural practices in that area over the last half-century. In 2015, a further claim to title