Alnus Mill. is a problematic genus of Betulaceae, and there are several intrageneric classifications for the genus. Alnus species are widely distributed in the Hyrcanian forest of Iran, and different species with some intraspecific taxonomic ranks including subspecies and varieties have been reported from this country. We evaluate seed micromorphology characteristics of ten taxa using scanning electron microscopy and light microscopy in the current study. The data were analyzed using SPSS and

more »

... SP software. Results revealed that qualitative characteristics such as seed shape, surface sculpturing pattern, presence of indumentum, and its type vary among the studied taxa and have diagnostic value. However, seed color was nearly stable among the taxa. Besides, quantitative variables highly differed among the taxa. In the UPGMA tree, Alnus taxa were clustered into three groups, and these groups were supported by PCA and PCO plots. According to the PCA bi-plot, some taxa were characterized by the particular characteristic(s) that was useful for their identification. In some cases taxa clustering was similar to those of previous phylogenetic and morphological studies. Our findings revealed that seed morphology characteristics are a valuable taxonomical tool in identifying most Alnus taxa, except for A. glutinosa subspecies, which have similar seed morphology features in common.