Genetic variation in morphology and growth characters of Acacia koa in theHawaiian Islands

Substantial phenotypic variation in Acacia koa has been reported in the Haw aiian Islands. We grew 72 A. koa families from the islands of O'ahu, Kaua'i , and Hawai'i in two common gardens to determine whether phenotypic differe nces in phyllode morphology, extrafloral nectary morphology, and other char acters have a genetic basis. Significant differences among islands and fami lies were observed for phyllode width, curvature, and pubescence, as well a s extrafloral nectary size and pigmentation, retention of juvenile leaves, and branch bark color. Seed shape also differed significantly among islands . Discriminant analysis revealed that families from the island of Hawai'i a re distinct from O'ahu and Kaua'i families. The O'ahu and Kaua'i families, however, could not be reliably distinguished based on sapling morphology or growth characters.