## 2 Results and Discussion
### Analysis of Picked Flowering Plant VOCs  
The volatile profile of _O. sphegodes_ subsp. _sphegodes_, _O. bertolonii_ subsp. _benacensis_ and _N. tridentata_ picked flowering plant samples consists of 56, 53 and 63 compounds, respectively (Table 2). As observed in \"_in vivo_\" orchids the aromatic profiles of the three picked flowering plant samples showed some distinctive differences in volatile fingerprint and the most representative compounds of all species were reported in Table 2 and Figure 2.  
Comparing the VOC profiles of \"_in vivo_\" and picked flowering plant samples of the same orchid species we showed some differences in secondary metabolite composition. In particular we observed an increased content of phenols and alcohols in _O. bertolonii_ subsp. _benacensis_ and _N. tridentata_ picked flowering orchid samples compared to living plants. Among these chemical classes we observed a large amount of 4-methylphenol in both orchid species (13,25% and 11,28% respectively) and of isoamylalcohol (13.03%) and 3-hexen-1-ol (8,52%) respectively in _O. bertolonii_ subsp. _benacensis_ and _N. tridentata_ fingerprint. An increase in hydrocarbons was also revealed in _O. sphegodes_ subsp. _sphegodes_ and _O. bertolonii_ subsp. _benacensis_ flowering plant samples and hexane, butane and nonane were considered the most representative compounds. Finally, we observed that flowering plant aromas showed a high content of terpen. In particular in this case the most representative compounds were \(\alpha\)-pinene (47.95%), thujene (3.05%) and cyclosativene (6.38%), followed in lesser amounts by \(\beta\)-myrcene (2.07%). Collecting plant tissues and flowers definitely impacts on the volatile profiles, causing dramatically alterations if compared with _in vivo_ and _in situ_ VOC samples. These alterations can be related to the mechanical damage provoked by the collection of plants [27] and in particular in this study different proportions of the various terpen were observed and a large increase of \(\alpha\)-pinene was detected especially in _O. sphegodes_ subsp. _sphegodes_ fingerprint. These data were confirmed also by literature [27]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{_O. spheodes_ subusp. _spheodes_} & \multicolumn{3}{c}{_O. bertoloniu_ subsp. _bencensis_} & \multicolumn{1}{c}{_N. tridentata_} \\ \hline
**Compounds** & **RT \({}^{*}\)** & **Mean (\(n=3\)) \({}^{*}\)** & **SD \({}^{4}\)** & **Mean (\(n=3\))** & **SD** & **Mean (\(n=3\))** & **SD** \\ \hline _Hydrocarbons_ & & & & & & & \\ hexane & 1.50 & 3.87\({}^{4}\) & 1.00 & 0.41 & 0.10 & 0.20 & 0.00 \\
2-methylbutadiene & 1.64 & 2.30 & 0.89 & 0.23 & 0.00 & ND & - \\ butane & 2.26 & ND & - & 6.93\({}^{4}\) & 3.11 & 0.10 & 0.05 \\ nonane & 3.25 & ND & - & 10.87\({}^{3}\) & 1.31 & 0.06 & 0.01 \\
1-tridece & 11.85 & ND & - & ND & - & 0.24 & 0.00 \\ tridece & 18.71 & 0.33 & 0.02 & ND & - & 0.15 & 0.00 \\ dodecane & 18.79 & 0.17 & 0.01 & ND & - & ND & - \\ pentadecane & 21.45 & 0.26 & 0.03 & ND & - & 7.52\({}^{4}\) & 1.60 \\ nonadecane & 22.47 & 0.23 & 0.00 & 0.33 & 0.07 & 0.37 & 0.34 \\ heptadecane & 25.98 & 0.13 & 0.02 & 0.17 & 0.00 & 0.06 & 0.00 \\
**Total** & & **7.56** & & **18.95** & & **11.09** & \\ _Aldehydes_ & & & & & & \\ pentanal & 4.78 & ND & - & 1.30 & 0.24 & 1.87 & 1.01 \\ esnal & 9.02 & 0.48 & 0.04 & 8.36\({}^{4}\) & 1.80 & 17.95\({}^{1}\) & 2.75 \\
3-hexanal & 12.22 & 0.28 & 0.02 & ND & - & 0.31 & 0.21 \\ heptanal & 13.94 & 0.12 & 0.01 & 0.06 & 0.02 & 0.89 & 0.00 \\
2-hexanal & 15.27 & 0.04 & 0.00 & 0.51 & 0.00 & 2.43 & 0.67 \\ octanal & 18.01 & 0.08 & 0.01 & 0.32 & 0.01 & ND & - \\
2-heptanal & 18.87 & ND & - & 0.15 & 0.05 & 0.25 & 0.01 \\ nonanal & 21.00 & 0.40 & 0.03 & 2.31 & 0.69 & ND & - \\
2-octenal & 21.74 & ND & - & ND & - & ND & - \\ decanal & 23.60 & ND & - & 0.15 & 0.03 & ND & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Identification of volatile organic compounds by HS-SPME-GCMS from picked flowering orchid samples.