Altitudinal gradient effect on morphometric variation and leaf symmetry of Platanus mexicana Moric

Morphometric variation and leaf symmetry was characterized in a population of Platanus mexicana along a riparian altitudinal gradient in Veracruz. A total of eight morphometric characters were evaluated in 1,800 leaves from 15 trees per site, collected at 70, 200, 600 and 1,700 m. Morphometric differences among sites (F-(24,F- 5189) = 21.1, P < 0.05) were determined using a discriminant function analysis. Characters related to length and width of leaves showed. significant intrapopulation differences (P <= 0.05). Based on Mahalanobis distances, the site located at 70 m is the most distant morphometrically. Cluster analysis showed ten different leaf groups along the altitudinal gradient. Differences in leaf size were observed, the leaves are larger at 70 m and decrease with altitude. The index of leaf symmetry of P. mexicana showed no significant differences (P > 0.05) among sites in the altitudinal gradient of the Colipa river. The results determine the responsiveness of P. mexicana to the environmental heterogeneity along the altitudinal gradient of the Colipa river.