Taxonomic significance based on palynological data of the genus Sedum in Iran

In the current survey, a detailed account in pollen morphology of 22 species of Sedum s.l. in Iran are presented using light (LM) and scanning electron microscopy (SEM). The pollen grains are radially symmetrical, isopolar, mostly trizonocolporate and rarely tetrazonocolporate, small-to-medium sized, prolate, subprolate, and prolate-spheroidal in shape. Two types of exine sculpturing (regulate-striate and regulate-striate-perforate) were recognized. Among the examined characters, pollen shape and size were taxonomically useful in the intergeneric classification and segregation of the genera Phedimus and Hylotelephium from Sedum s.s.. Numerical analysis (unweighted pair-group method with arithmetic averages and principal components analysis) of 15 qualitative and quantitative characters also confirmed the delimitation of these genera. The PCA analysis of the selected pollen morphological characters indicated the alliance of two sections Sedum and Epeteium. Pollen morphological characters are also taxonomically informative to provide good data for species delimitation.