study of the chromosome number in some species of the genusCirsium (Compositae) in Khorasan province

Aim and Background. The genus Cirsium is one of the genera in Compositae w hich includes 250-300 species distributed all over the world. They are herbaceous, perennial or rarely annual and usually distributed in Africa, Europe and America. Materials and Methods. In cytogenetical studies, 4 different species were studied. The methods that were used in the chromosomal studies are as are as follows: pretreatment, fixation, hydrolyzation, staining and mounting. Also chromosome number and ploidy level were recorded.Results. The somatic chromosome number in C. congestum and C. turkestanicum was 2n=34 and was 2n=68 in C. vulgare and C. respectively.Conclusion. Based on this study C. congestum and C. turkestanicum are diploid and somatic chromosome number in both species is 2n=2x=34 and C. vulgare and C. arvense are tetraploid and somatic chromosome number is 2n=4x= Respectively.