Assessment of morphological diversity among different populations of Thymus daenensis Celak.

Thymus daenensis Celak. belonging to Lamiaceae family, is an endemic medicinal plants of Iran that has been found as a rich source for essential oil and thymol. The evaluation of the morphological traits of different populations of this species is necessary for its domestication. Eight populations of this plant were collected from three provinces of Markazi (Shazand, Khan e miran bala, Khan e miran paien and Arak), Hamedan (Malayer 1, Malayer 2 and Jovzan) and Lorestan (Zaghe) at full flowering period. 31 quantitative and qualitative traits were evaluated. The results indicated that there was a significant difference between the populations for most studied traits. The stem cork, calyx color, leaf cork and number of essential oil glands had the highest coefficient of variation among the populations. The maximum length and diameter of inflorescences and leaf length in Zaghe, the highest leaf area in Shazand, the highest number of essential glands and leaf width in Khan e miran bala and the highest number of flowers in inflorescences was observed in Malayer 1 population. Some significant positive and negative correlations were observed between traits. Cluster analysis of populations based on measured traits putted populations in three clusters (Zaghe, Shazand and other populations). In general, the results indicated a high variation among populations, which could be due to habitat conditions or populations genetic. We suggest to repeat such studies to investigate the impact of habitat conditions on morphological traits of this species. This can be helpful for choosing the best population for domestication.