Chromosomal number of Carduus pycnocephalus L. in the west of Iran

Carduus L. species (belong to Asteraceae Bercht. and J. Pres) replace endemic plant species by forming dense colonies and can compete with native vegetation for light, nutrition, and moisture. In order to obtain more information about this invasive genus, the chromosomal number of Carduus pycnocephalus L. were investigated from Hamedan and Kermanshah provinces in the west of Iran. 14 special stations were selected of some parts of these provinces. Chromosomal counting was done in the metaphase stage of the root meristems by seed germination and by using the standard squash method. Results showed that chromosomal number in these studied taxa was 2n=2x=34 in 14 populations gathered in this research. By comparing the chromosome number found in this study with previous research, this chromosome number is belonging to C. pycnocephalus subsp. arabicus (Jacq. ex Murray) Nyman. Therefore, the diploid chromosome number in the taxa of this species can be taxonomical value.