Centaurea aucheri (DC.) Wagenitz is one of the species of Asteraceae that has not been the subject of many investigations. Different species of this genus have been used in traditional medicine. In this investigation C. aucheri was collected from Khanesorkh of Kerman and the essential oil of the aerial parts of plant was extracted by Clevenger apparatus and analyzed by GC-MS. Identification of the components of oils were based on their retention indices and mass spectra data in comparison with those reported in literatures. The amount of essential oil was 0.16% and 22 substances consisting 80.03% of the composition of the essential oil were identified. The main compounds were caryophyllene oxide (19.44%), β-caryophyllene (14%), Geremacrene-D (13.38%). The essential oil was rich in sesquiterpene oil.

Nigella sativa L., belonging to the family of Ranunculaceae, is grown for its seeds, which are used in food and medicinal industries. In this study, the volatile oil compositions of 16 cultivars of N. Sativa collected from different parts of Iran were evaluated, and then the chemotaxonomic study was done. The analysis of volatile oils was done using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), which identified 22 components. Major constituents of the collected cultivars were p-cymene (27.7-38.1%), thymoquinone (19.5-40.9%), thymohydroquinone (5.8-9.6%), α-thujene (5.1-7.2%), and trans-4-methoxythujane (3.4-4.8%). Then, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to assess differences in volatile oil composition. PCA displayed that different groups of cultivars were characterized by high contents of specific compounds. The results of chemometric analysis displayed that PCA was approximately in agreement with HCA, and allowed classification of the studied cultivars into four groups including Group-A (Ns-4, Ns-5, and Ns-16); Group-B (Ns-1), Group-C (Ns-2, Ns-3, Ns-7, Ns-8, and Ns-12), and Group-D (Ns-6, Ns-9, Ns-10, Ns-11, Ns-13, Ns-14, and Ns-15). This is the first study on N. sativa in a vast geographical context in Iran to this extent, using different chemometric techniques. The results of this study can offer scientific data for germplasm of N. sativa in Iran and for breeding programs to improve developed cultivars.