Koa (Hawaiian Acacia) is one of Hawaiʻi’s largest and most iconic native trees, forming the backbone of upland mesic and cloud forests and supporting over 30 native bird species. This fast-growing nitrogen-fixing legume enriches volcanic soils, provides canopy cover for understory plants, and intercepts mist and rainfall to sustain watershed function. Koa was historically used for canoes, tools, surfboards, and ceremonial objects, and its wood remains culturally and economically valued. Although threatened by grazing, logging, and koa wilt, reforestation efforts highlight koa as a keystone species essential for ecosystem restoration (Native Plants Hawaii, University of Hawaiʻi CTAHR, Kākou Collective).