Essential oil composition and variability of Thymus lotocephalus and Thymus x mourae

The composition of the essential oils of four populations of Thymus lotocep halus G. Lopez and R. Morales and one population of T. x mourae Paiva and S algueiro, two endemic taxa from Portugal, was investigated mainly by GC and GC-MS. Tx mourae is a natural hybrid between T. lotocephalus and T. mastic hina (L.) L. subsp. donyanae R. Morales, which essential oil was analysed f or the first time. In its oil, it was possible to find compounds of both pa rents, which could enable us to confirm its intermediate status between tho se two taxa. 1,8-Cineole and borneol were the main constituents in the esse ntial oil of T. x mourae, whereas linalool, geranyl acetate and 1,8-cineol were the major ones in T. lotocephalus. Intermedeol was also an important c onstituent in the oils of both taxa. Nevertheless, the volatile oils of the four populations investigated of T. lotocephalus showed important differen ces among the main constituents. In order to study their infraspecific vari ability, the results obtained in the analysis of individual plants were sub mitted to a Principal Component and Chemometric Cluster Analyses. Five type s of essential oils were found: linalool, 1,8-cineole, linalool/1,8-cineole , linalyl acetate/linalool and geranyl acetate. (C) 2000 Elsevier Science L td. All rights reserved.