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The genus Crataegus L. has a wide distribution in Iran. Induviduals of Crataegus meyeri Pojark. show morphological variations in different regions. In this research, the effects of climatic variations on morphological traits of C. meyeri were studied. Seventy five specimens collected from nine provinces of Iran were measured in two sets of quantitative and qualitative traits. Statistical analysis of climatic data and morphological traits showed that wind and temperature were the most effective factors affecting the variety of morphological traits including leaf blade of short shoot and flowering shoot, indumentum of fruit surface and fruit shape. Relative humidity has also been correlated with the shape of the fruit base. Quantitative traits of leaf blade of short shoots and flowering shoots showed the highest correlation and leaf blade of elongate shoots with the least statistical correlation with climatic data.