Leaf morphological variation in beech (Fagus sylvatica L.) populations in Greece and its relation to their post-glacial origin

Diversity in leaf morphological traits was assessed in 38 Greek Fagus sylvatica populations, covering the distribution of the species in the country. The relationship between the post-glacial origin of these populations and leaf morphology was investigated. The results showed a complex and geographically continuous morphological diversity pattern, influenced mainly by traits expressing leaf size, leaf shape and petiole length. Two simultaneous trends appeared to be responsible for the existing diversity pattern. One was geographical, with leaf types resembling F. sylvatica subsp. sylvatica occurring in the western part of the distribution of beech in Greece and types resembling F. sylvatica subsp. orientalis being dominant in the eastern part. A second trend seemed to be connected with the post-glacial origin of the populations, as described by previous plastid DNA haplotype studies of the same trees. The genetic background and the possible adaptation of beech populations to different environmental conditions have resulted in a complex morphological pattern, especially in areas in which different post-glacial lineages appear to meet.