Multivariate statistical analysis of the essential oil composition of Thymus praecox Opiz ssp polytrichus (Kern. ex Borb,) Ronn. collected in the Tyrolean Alps

The essential oils of 141 individual plants of Thymus praecox Opiz ssp. polytrichus (Kern. ex Borb.) Ronn., emend. Jalas, collected at 16 localities in the Austrian and Italian Alps (Tyrol and South Tyrol), were investigated concerning their composition and the variations therein. In total, 60 components, almost exclusively monoterpenes and sesquiterpenes, were identified by GC and GC-MS. The patterns of the oils were processed by means of multivariate statistical analysis (MSA) including factor analysis (FA), cluster analysis (CA) and discriminant analysis (DA). The most plausible result, revealing 12 clusters, was obtained by a modified CA method based on the average linkage method with the Pearson correlation. Considering all other statistical results obtained, 12 oil types became evident with the following type-characterising compounds: thymol, geraniol/geranyl acetate, trans-sabinene hydrate/terpinen-4-ol, α-terpineol, linalol, linalol/linalyl acetate, borneol, trans-nerolidol, hedycaryol, T-cadinol, germacra-1(10),5-dien-4-ol, and germacra-1(10),4-dien-6-ol. All these oil types have been found before in other Thymus species. The thymol type, found for 46 samples, represented the most dominant oil type. The chemical similarity with Mediterranean and North Atlantic Thymus species indicates a mixing of southern and northern elements in the Alps, which is also reflected in the overlapping morphological characters of T. praecox ssp. polytrichus. Copyright (C) 2000 John Wiley and Sons, Ltd.