One of the anticipated results of the climate change will be the alteration of the current distribution areas of forest tree species. In light of these processes, it is expected that the role of one of Europe’s significant forest forming species –– European beech, Fagus sylvatica L. –– will be increased, particularly in the north-eastern part of its distribution, the border of which runs through the Polish territory. The study was aimed to determine the morphological characters diversity of beech leaves from 10 provenances, grown on experimental plots, differing in spring flushing. From four years of observation, five provenances with early and late flushing were selected. Seven morphological characters of the leaves were analysed. The study has shown, that beech trees that begin to grow late in spring, develop smaller leaves than those referred to as early flushing. Moreover, morphological distinction of beech leaves from two centres of its distribution in Poland, i.e. northern and southern, has been confirmed. The obtained information on the provenance variability of beech and its adaptive characters are important for breeding and selection tasks. The use of the obtained knowledge will help in the proper implementation of forestry goals, which include the possibility to use forest reproductive material to ensure lasting tree stand stability in the future.

Keywords: Fagus sylvatica L., leaf morphological traits, phenology, variability