| Summary: | The genus Sorbus consists of small to medium-sized trees primarily found in coastal areas, with three European hotspots for diversification: Fennoscandia, South-East Europe, and Britain. Taxonomic classification of Sorbus in Europe is still unresolved, and this study aims to address this issue by examining the pollen morphology of different Sorbus hybrids. Pollen morphology of 16 specimens from 13 species of Sorbus, Aria and Hedlundia, some of which are common, while others are endemic and listed as threatened species, were studied. Measurements of the polar and equatorial axis of all pollen show that there are variations in pollen size and shape among different hybrids, with correlation between polyploidy levels and the width of the pollen. Surface structures of pollen were observed using SEM. Principal Component Analysis (PCA) was performed to analyze the pollen characters, and the results show that it is possible to separate Aria from Sorbus and Hedlundia based on the length of the pollen grain, while the number of perforations is important for classification within Hedlundia. The study concludes that pollen morphology can be a useful tool for distinguishing between different Sorbus hybrids and can thus aid in understanding their past distributions.
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