Leaf cuticle micromorphology of Fagus L. (Fagaceae) species

Abstract

Cuticle micromorphology of all eight species of Fagus and an outgroup were examined in the present study. The genus Trigonobalanus was selected as the outgroup. Thirteen characteristics of the inner surface and five of the outer surface of the cuticle were described. Some characteristics, such as the subsidiary cell shape, size of stomata, arrangement of subsidiary cell, shape of anticlinal and periclinal cell walls, texture of periclinal cell wall, development epicuticular wax, and presence of papillae, were considered important for infrageneric classification. The topology was obtained from the analysis using two major lineages: (1) Fagus engleriana + Fagus japonica + Fagus longipetiolata and (2) Fagus sylvatica + Fagus crenata + Fagus lucida + Fagus hayatae + Fagus grandifolia. The first clade supported a bootstrap value of 98% and the second clade a bootstrap value of 97%. Based on the cuticle morphology, our results support the previous study, by revealing F. engleriana, F. japonica, and F. longipetiolata with long peduncles in one group and the remaining extant species of short- to medium-length peduncles in another group. In addition, molecular phylogenetic study of Fagus based on ribosomal DNA ITS and chloroplast DNA sequences data supports this assemblage. This study shows that cuticle micromorphological characteristics provide useful and important information for analyzing the evolutionary aspects of Fagus.