Acacia heterophylla 1.4 million years ago. "A. heterophylla" sequences nest within those of the more diverse "A. koa", making the latter species paraphyletic. Both species are descended from an ancestral species in Australia, presumably their sister species, "Acacia melanoxylon"; the means of dispersal to Hawaii and then to Réunion (the latter trip a distance of 18,000 km) is thought to have been seed-carrying by birds such as petrels (the seeds of these species are not adapted for prolonged immersion in seawater). Both species also have very similar ecological niches, which differ from that of "A. melanoxylon". Acacia heterophylla Acacia heterophylla, the highland
Koa wilt species of koa-finches, "Rhodacanthis palmeri" and "R. flaviceps", which fed on green koa seed pods. These species are now extinct due to habitat loss and avian malaria. It is important to preserve the remaining koa populations to helpt to avoid further native bird extinctions. Koa also has great cultural importance for native Hawaiians. The name “koa” means "brave, bold, fearless" or "warrior" in Hawaiian. Koa wood was used extensively in ancient Hawaiian society for constructing houses, spears, tools, canoe paddles, kahili (feathered standards of royalty), calabashes, ceremonies, and surfboards. Canoes were, and still are, carved from the trunks of koa