Karyotypic study of four Thymus species T. lancifolius), T. daenensis, T. fedtschenkoi, pubescens. T)

Thymus as a member of the Lamiaceae family, is a prennial plant and a very important medicinal plant. For studying of chromosomes morphology in Thymus, the seeds of 5 populations, representing 4 species, namely, T. lancifolius, T. daenensis sub sp. daenensis (2 samples), T. fedtschenkoi and T. pubescens were prepared. Mitotic chromosomes were studied in meristematic cells of root tips obtained from germinated seeds. The basic chromosome number was X=15 in all of the populations, but their ploidy level varied and karyotypic formula of T. lancifolius was 25m+5sm (2n=2x=30), T. daenensis sub sp. Daenensis were 22m+8sm and 30m, T. fedtschenkoi was 23m+7sm and T. pubescens was 30m. Based on intra-asymmetry chromosome index, T. daenensis sub sp. daenensis had the most asymmetric and evolutionary karyotypes and T. pubescens had the most symmetric karyotypes. Analysis of variance based on an unbalanced completely randomized design showed a significant difference (P<0.01) among the populations for all of the traits. Cluster analysis classified the populations into two groups. T. daenensis was classified to first class, T. fedtschenkoi and T. pubescens allocated to the second class