Note on use of some micro-morphological features in distinction of three pubescent oaks in Croatia

The abaxial epidermis of pubescent oaks, Quercus brachyphylla Kotschy, Quercus dalmatica Radic and Quercus pubescens Willd., was studied with the Scanning Electron Microscope. Micro-morphological features (surface of trichomes, stomata, ordinary epidermal cells and wax) do not permit to distinguish the three oaks species. Nevertheless, the difference among the taxa exist in leaf phenology and time of appearance and rate of degradation of epicuticular wax crystalloids. Alteration of wax crystalloids into amorphous wax is interpreted in favour of natural phenomenon of the wax ageing and degradation.