Fruit and leaf variation in mulberry (Morus L.) was studied in 1 984 and 1985 at Bowling Green, Kentucky. Significant differences in fruit and leaf characteristics were found among branches within trees, among trees, and between years. High levels of phenotypic plasticity were evident for both fruit and leaf characteristics. The author suggests that phenotypic plasticity may have contributed to mulberry’s growth and survival under disruptive environmental conditions, but may have limited its competitive ability with other tree species.