Marrubium L., is one of the problematic genera of Lamiaceae and comprises of about 40 taxa, which some of them grow in Iran. In the present evaluation, we investigated infrageneric and infraspecific variations among six Iranian Marrubium species using morphological and anatomical traits, genetic structure, chloroplastic genome (CP-DNA) and ITS regions of nuclear ribosomal (nrDNA). Five individuals were collected per each species. Most of the studied qualitative and quantitative morphological features differed significantly (P ≤ 0.00) among the species, and we detected 5 morphotypes in the PCA plot. Leaf anatomical structure was dorsi-ventral in all the species. We observed significant variations in most of the studied anatomical variables, and the species were clustered in three groups. Results of genetic diversity study revealed that the total genetic diversity (Ht) was higher than mean difference within each species (HS). These findings were supported by ANOVA test, Gst and Nm values. The studied species were divided into 5 genotypes according to STRUCTURE analysis and UPGMA tree. The studied species were clustered separately in CP- DNA and ITS cladograms of phylogenetic study. High infraspecific divergences were detected in the studied species. The evaluated taxonomical markers have enough potential to separate the species, but the clustering patterns of the species were not the same, except those for M. parviflorum and M. crassidens that were clustered in most of cases. It can be concluded that evaluated species reveal a complex group resulting from high infraspecific variations in the evaluated characteristics.
