Micromorphology of fern spores as a tool in taxonomy of East-Central European species from the family Aspleniaceae (Polypodiopsida)

The family Aspleniaceae consists of ca. 730 fern species found primarily in the tropics but present also in the temperate zone. Recently, researchers have been increasingly interested in spore morphology, as it provides valuable information used in taxonomic and phylogenetic analyses. This study aimed to (1) describe in detail spore morphology in species of the family Aspleniaceae from Central and Eastern Europe; (2) attempt to use their features in taxonomic analyses; and (3) create a key to species identification on the basis of spores. e study was based on Asplenium spores of 10 species from 57 localities. The morphological type of spores was very similar in all the studied species, whereas spore microsculpture varied widely between and within species. This makes it difficult to use spores for species identification. Nevertheless, spore morphology allows the identification of six species, while the others form groups composed of 2–3 species each. In the group consisting of A. adulterinum, A. trichomanes, and A. ruta-muraria, the last species is distinguished by larger spore size (more than 50 μm long).