In this study, chromosome number and some morphological features of 6 populations of Tanacetum pinnatum Boiss. collected from different localities in Hamedan province, Iran, are reported. In this species, five populations with diploid chromosome number (2n=2x=18) and one population with tetraploid chromosome number (2n=4x=36) were found. Some vegetative and reproductive featuresweremeasuredmorphometricaly. Pollen grains characteristics were also studied using light microscopy. Morphological and palynological data were analyzed by MVSP software with UPGMA method. Analysis indicated significant differences among the populations and showed that tetraploid population is quit deferent fromdiploid ones. It seems that there are significant differences depending on ploidy level, morphological features and pollen characteristic in tetraploid plant and diploids.
