Palynological analysis of genus Geranium (Geraniaceae) and its systematic implications using scanning electron microscopy

Pollen morphology of 23 species belonging to Geranium have been studied in details, which represent eight sections of two subgenera i.e., G. sect. Dissecta, Geranium, and Tuberosa of subgen. Geranium, Divaricata, Lucida, Ruberta and Trilopha of subgen. Robertium. These plant species were collected from different phytogeographical regions of Iran. The palynological investigation was done using scanning electron microscopy (SEM) techniques. Different palyno-morphological features have been observed, and the closely related species were distinguished. We used different multivariate statistical methods to reveal the species relationships. Ward clustering analyses have been done to check out the relationship among the species. The shapes of pollen grains were monad, radially symmetric, isopolar, apertures were tricolporate, and of spheroid, prolate-spheroid or sub-prolate classes. Three pollen types were recognized on the basis of differences in exine sculpturing pattern: reticulate-clavate, striate-rugulate, reticulum cristatum with clavae. Observed differences were not of diagnostic importance in subgenera and sections level. The main objective of this study is to find distinguish pollen characters in the species of the genus Geranium and to elucidate their systematics importance.