Results obtained from the cluster analysis showed the existence of a high inter-production variability within the essential oil of O. vulgare From the six production-samples submitted to multivariate analysis, two well-defined groups of essential oil were differentiated by cluster analysis (Fig. 2). Based on the data, (select variables > 0.2% of 42 essential oil components from six production areas) two subclusters can be observed: the first subset contains three production sites of samples S1, S3, and S4 (Kunlun Mountain of Hetian, Pakistan, Hetian), the second subset includes samples S2 (Shangqiu of Henan), S5 (Anhui) and S6 (Yili).