We studied the relationships between morphometric parameters of leaves of Rhododendron mucronulatum and climate features at the northern limit of its distribution. A great morphological diversity in leaf shapes, including strong deviations from the typical lanceolate and acute leaf shape was revealed. We found that the frequency of an elliptic shape with obtuse apex is the result of morphological adaptation to particular climatic conditions and that the diversity of leaf morphological features were strongly correlated with temperature and annual precipitation. The climatic parameters of the winter period were found to be more important for determining the leaf shape than the climate during the growing season.