Chemotaxonomic significance of the volatiles in the genus Stachys (Lamiaceae): Essential oil composition of four Balkan Stachys species

Gas chromatography (GC) and GC/MS analysis of the essential oil composition of Stachys germanica ssp. heldreichii (Boiss) Hayek, Stachys iva Griseb., Stachys plumosa Griseb. and Stachys scardica Griseb., Balkan Peninsula endemics, has been carried out. Eighty-three compounds, which accounted for 96.3–99.6% of the total composition of the oils, have been identified. This is the first report on the composition of S. iva volatiles and on the occurrence in the family Lamiaceae of (Z)-nuciferyl isobutyrate (and other nuciferyl esters, higher that acetates), which was found as one of the major components of oils from S. germanica ssp. heldreichii and S. iva. The chemotaxonomic relationships within the genus Stachys and with those of related Lamioideae have been discussed in detail. Nuciferyl esters and volatile diterpenoids were used as marker compounds. The high degree of variation in the main constituents, especially of germacrene D and its congeners, was correlated with possible rearrangements under hydro-distillation conditions. Thus, due to the possible artefactual origin of these compounds they seem to be unreliable as chemotaxonomic markers.