Karyotypic analysis on Stachys lavandulifolia Vahl from Northwest of Iran

Chromosomal characteristics of three populations of Stachys lavandulifolia Vahl were studied using Hematoxilin staining of meristamtic root tips. Karyograms of each population were made and karyotypic characteristics including the chromosome number, long and short arms length, arm ratio index and relative length of each chromosome were measured. Results showed that all of the populations had 2n=68 chromosomes and there were differences between the populations in terms of chromosome formula. Chromosome size of the species is small and varied between 0.93 to 2.45 µm in the populations. The base chromosome number of the species is x=17 and it seems that S. lavandulifolia Vahl is a tetraploid species. There was much diversity in the studied populations in terms of most chromosome characteristics. Sarab and Ardabil populations being in the 2A class according to Stebbins classification showed symmetrical karyotype while Meshkynshahr population located in 2B class and had an asymmetric karyotype compared with other populations.