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Essential oils of Baccharis uncinella DC and B. dracunculifolia DC collected from different wild populations growing in Bolivia, southern Brazil and Uruguay were analysed using gas chromatography and gas chromatographymass spectrometry techniques, to check for chemical variability. Cluster analysis led to the identi¼cation of two chemotypes for B. dracunculifolia, related to aromadendrane-or cadinane-derived components. As the timing of sampling of the plant material may have an in½uence on the composition of the essential oil isolated, the seasonal in½uence at the moment of harvesting was studied for two populations of each species. The results suggested that the ½owering season was optimal both species and this supported the practice of harvesting at the full bloom stage.

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Cold-pressing and hydrodistilled peel oils of two Brazilian mandarin cultivars, commonly called Cai and Montenegrina (Citrus deliciosa Tenore), were obtained from fruits collected on mandarin trees submitted to the same pedoclimatic and cultural conditions. Their chemical composition and seasonal variation of the main volatile constituents were investigated by capillary GC and GC-MS, and the results were submitted to statistical analysis. To better characterize the oils, the enantiomeric distribution ratio of seven components (alpha-pinene, sabinene, beta-pinene, limonene, linalool, terpinen-4-ol, and alpha-terpineol) was determined by multidimensional gas chromatography (MDGC). The similarities found between both C. deliciosa cultivars are strong evidence for the hypothesis that Montenegrina originated from Cai as previously reported from agronomic studies.

The essential oil from aerial parts of Baccharis uncinella DC. was analysed using a combination of GC and GC-MS. Kováts retention indices were also calculated to complete the identification. The main components identified were˛-pinene (16%),ˇ-pinene (15%), limonene (13%), spathulenol (10%), globulol (5%), (E)-nerolidol (4%), bicyclogermacrene (3%) and terpinen-4-ol (2%).