Taxonomic importance of pollen micromorphology in Prunus L. subgenus Cerasus Pers. (Rosaceae) from Iran

Prunus subgenus Cerasus belongs to the Rosaceae family with about 100 species in the world, of which 19 taxa are distributed in Iran. Pollen micromorphological traits of the Iranian taxa belonging to three sections, (Microcerasus, Cerasus, and Mahaleb) were examined using light and scanning electron microscopes. The hierarchical clustering method and principal component analysis of the pollen traits were performed using InfoStat. The results showed that in the subgenus Cerasus pollen grains are monad, radially symmetrical, isopolar, tricolpate to tricolporate, and medium-sized. Pollen shape is rectangular to cylindrical in the equatorial view and triangular to circular in the polar view. The exine ornamentation is striate with or without perforations. The studied pollen can be divided into two types and six subtypes. The rugulate exine ornamentation was only found in P. pseudoprostrata. Ward’s hierarchical clustering method and principal component analysis results did not support the existing sectional delimitation of taxa. However, a high variation in pollen grain characteristics could be observed in taxa within the subgenus Cerasus, especially in dwarf cherries (sect. Microcerasus). These differences are remarkable among closely related species, such as P. microcarpa and its allies. Finally, an identification key to the species is provided.