Acacia koa is a large tree becoming 50 feet tall in cultivation, but very old trees can become much taller. At maturity, the trees are 10 to 25 feet in diameter. The “leaves” are not true leaves; they are modified leaf stems, or phyllodes, which function as leaves. These crescent-shaped phyllodes are gray-green and range from 3 to 9 1/2 inches in length. The small, yellow, powder-puff shaped flowers occur in clusters either at the ends of the branches or at the bases of the phyllodes. There are three forms of Acacia koa which are sometimes considered subspecies. One of these, subspecies koaia, is shorter with a more gnarled appearance and is commonly considered horticulturally distinct. (Bornhorst 1996; Wagner 1990) cacia koa is endemic to Hawai’i and is found on all the main islands except Kaho’olawe and Ni’ihau. It is often a dominant plant in dry to wet forests at elevations ranging from 200 to 6,500 feet.