Palynological study of the genus Calendula in Iran

The genus Calendula L. belongs to Asteraceae family and Calenduleae tribe. The main centers of it are Mediterranean area, middle east and central Europe and then it distributed to other regions. Here we study some species of Calendula species palynologicaly. The pollen grains separated from herbarium specimens and have investigated by light microscope and Scanning electron microscope (SEM). The pollen was trizonocolporate and tetra zonocolporate and based on P/E ratio in equatorial view the shapes were different. Also the sculpturing was echinate. The pollen characters were analyzed by using multi variate statistical analysis and the species relationships were evaluated by using cluster analysis and PCA diagram. Moreover the most variable characters by factor analysis were determined and use to separate species. Then we showed that some characters such as pollen shape, length of polar axis, length of colpus, distance between spines, pore diameter and diameter of spine base could useful for distinguishing the species.