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 Kannon the Soto school. General Iwane Matsui who commanded the Shanghai Expeditionary Force at the outbreak of the Second Sino-Japanese War built the Koa Kannon statue after retiring from the service in 1940 to honor the officers and men of both China and Japan who fell in battle in the name of consecrating equally both friend and enemy. The statue was made using clay from battlefields, including from the vicinity of Nanjing where Matsui served. On 24 February 1940 the consecration ceremony was performed in the presence of Tessui Oshima, a high-ranking Jodo Buddhist monk from Zojo-ji, and other distinguished figures.