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
Scissor-billed koa finch Kanaloa" ("Kanaloa kahoolawensis") and "koaia" ("Acacia koaia") were probably important food sources, and it may have eaten caterpillars and "aalii" ("Dodonaea viscosa") berries. Due to its early extinction, very little is known about this species. It is only known from fossil remains. Other Hawaiian honeycreepers are known to have become extinct or very rare due to habitat loss, introduced predators and avian diseases. It is possible the extinction of the scissor-billed koa finch also involved these factors. Scissor-billed koa finch The scissor-billed koa finch, ("Rhodacanthis forfex") or scissor finch is an extinct species of Hawaiian honeycreeper. Of the four species