## 3 Discussion
Comparable to our results, variations in bicyclogermacre content were observed in aroma compounds isolated by hydrodistillation of dried aerial parts from different populations of _S. scardica_ and _S. raseeri_ from Macedonia [29]. Moreover, it was reported by [PERSON] et al. [46] in their extensive study conducted on 50 _Sideritis_ taxa from the section _Empedchia_ that viridiflorol was one of the major components isolated by hydrodistillation from _S. perfoliata_ L. from Turkey, while the same compound was not observed for this species in a subsequent study done by the same authors conducted on only two species [47]. Additionally, viridiflorol was found as one of the major constituents of EO isolated by hydrodistillation from _S. montana_ subsp. _montana_ from Turkey together with germacrene D, bicyclogermacrene and (_E_)-\(\beta\)-farmesene [18]. In the present study, the predominant compounds for _S. montana_ extracted with DVB/CAR/PDMS fiber were germacrene D, _trans_-\(\beta\)-caryophyllene, \(\delta\)-cadinene, bicyclogermacrene, limonene and _trans_-\(\beta\)-farmesene, while with PDMS/DVB fiber germacrene D was followed by bicyclogermacrene, _trans_-caryophyllene, limonene and _trans_-\(\beta\)-farmesene. In investigated samples of _S. montana_, as well as in the samples of _S. romana_ other than _S. romana_ M, viridiflorol was found only in trace amounts (\(<\)1%), while ledene was observed only in _S. montana_ from Jezevic (_S. montana_ J), the latter being the previously collected and thus older of the two investigated samples of _S. montana_ (stored for a slightly longer period before GC-MS analysis). Considering that a significantly lower amount of bicyclogermacrene was detected in the same sample compared to _S. montana_ from Moser (_S. montana_ M), ledene may have been formed during the drying and storage period from the aforementioned bicyclogermacrene. Our results considering the major VOCs of investigated populations of _S. montana_ are in accordance with the results of previous studies from Bulgaria [22], Turkey [18], Serbia [25] and Italy [23], in which germacrene D predominated in the chemical composition of EOs isolated from aerial parts by hydrodistillation, usually being followed by bicyclogermacrene. Different major compounds were reported for _S. montana_ from Iran, in which geraniol particularly predominated in the EO obtained by hydrodistillation from the flowering spikes of the plant [26], while it was not detected in our samples of _S. montana_ aerial parts, as well as for _S. montana_ subsp. _montana_ from Turkey, in which \(\beta\)-caryophyllene, \(\alpha\)-pinene and \(\beta\)-pinene were found to be the major compounds of the hydrodistilled EO obtained from aerial parts of the plant [24]. The present study also indicated that _S. montana_, unlike _S. romana_, is characterized by several sesquiterpene hydrocarbons having a cadalane skeleton (\(\delta\)-cadinene, \(\gamma\)-cadinene, \(\alpha\)-amorphene, \(\alpha\)-muvrolactone, \(\alpha\)-cadinene, and cadina-1,4-diene). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Species** & \begin{tabular}{c} **Sample** \\ **Code** \\ \end{tabular}  & \begin{tabular}{c} **Voucher** \\ **No.** \\ \end{tabular}  & **Location** & \begin{tabular}{c} **Date of** \\ **Collection** \\ \end{tabular}  & **Latitude** & **Longitude** & \ \begin{tabular}{c} **Köppen Climate** \\ **Classification 1** \\ \end{tabular}  \\ \hline _S. romana_ & _S. romana_ K & 18 021 & \begin{tabular}{c} Istra, \\ Kamenjak \\ Dalmatia, \\ Blato \\ Dalmatia, \\ Molnig Bay \\ Dalmatia, \\ Dalmatia, \\ Bräc, \\ Praznica \\ \end{tabular}