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
Acacia koa arranged end-to-end in the pod, rather than side-by-side. The phyllodes are also usually straighter, though this character is variable in both species. The wood is denser, harder, and more finely grained than koa wood. Koaia has been much more heavily impacted by cattle and is now rare, but can be seen on ranch land in North Kohala. The koa population has suffered from grazing and logging. Many wet forest areas, where the largest koa grow, have been logged out, and it now comes largely from dead or dying trees or farms on private lands. Although formerly used for outrigger canoes,