Abstract:In order to understand the morphological variation of endangered distylous species Primula merrilliana populations, 14 morphological characters of 4 core and 3 peripheral populations were studied. The results showed that coefficient of variation (CV) of morphological characters ranged from 0.09 to 0.50 in core populations and from 0.05 to 0.56 in peripheral populations, showing no significant difference. In 14 morphological characters, the average of 8 traits in core populations was significantly higher than that of peripheral populations (P < 0.05), while only that of 3 traits, such as corolla diameter, corolla lobe width and leave width, in peripheral populations was higher than that in core populations. The reciprocity index of distylous flowers in core populations were relatively high and stable (0.83-0.90), meaning that the two types flower in core populations reciprocally matched well, while the reciprocity index varied greatly in peripheral populations (0.60-0.93). Therefore, the morphological variation of core and peripheral populations of distylous species P. merrilliana basically supported the “rich center model” hypothesis, the P. merrilliana protection strategy was also discussed.