## 2 Results
### Chemometric Analysis of Volatile Organic Compounds  
A qualitative heatmap was performed considering only the presence or absence of the volatile organic compounds into the different species (Figure 1). The qualitative heatmap's objective was to observe the specificities and similarities of each species concerning their aromatic profile composition. The main aim was to easily see the composition of VOCs of each species and evaluate the main differences. Indeed, the 14 _Tillandsia_ species are grouped into 4 groups in the dendrogram: the first one, with _T. aeranthos_, _T. bergeri_, _T. aeranthos_ x _T. bergeri_, _T. aeranthos_ _'uruguay'_, _T. ionantha_, _T. tenuifolia_, _T. cacticola_, _T. albertiana_, _T. ixoides_ and _T. lorentziana._; the second one, with _T. paleacea_; the third one, with _T. recuruta_ and _T. didisticha_' and the fourth one, with _T. bandensis_. Regarding the heatmap, the compounds that are specific of a species can be easily identified. Indeed, for _T. bandensis_, 10 compounds are only present in this species: methyleugenol (37), eugenol (30), hexadecanal (55), tetradecanal (54), hexadecanol (42), methyl ortho-anisate (35), methyl nicotinate (61), terpinolene (11), \(\gamma\)-terpinene (10), and isomyocorene (7). Likewise, _T. paleacea_ has seven compounds specific to its flowers: benzyl isovalerate (36), butyl benzoate (34), benzyl butyrate (33), eucalypt (6), \(\beta\)-myrorene (2), limonene (8), and \(\alpha\)-terpineol (12). Moreover, this qualitative heatmap allows for the identification of the main compounds present in most of the species studied. For instance, as explained above, benzaldehyde (22), benzacetaldehyde (24), hexanol (40), hexanal (43), heptanal (44), octanal (47), nonanal (49), and furan-2-pentyl (59) are the 8 compounds most represented in the 14 species of _Tillandsia_ studied (top right corner with green cells in the heatmap). Furthermore, this heatmap allows identifying the _Tillandsia_ species with only few VOCs extracted from flowers such as _T. didisticha_. To help with the identification of the volatile compounds that allow us to highlight similarities or differences between the 14 different species, a principal component analysis (PCA) was used to analyze the 65 compounds identified in this study. Two PCA were realized. The first one corresponds to two _Tillandsia_ species: _T. aeranthos_ and _T. bergeri_ and their hybrids: _T. aeranthos x T. bergeri_. As these species are widely cultivated in the _Tillandsia_ PROD plant nursery and are well acclimated to the Occitanie region, it is interesting to study them apart from the 11 other _Tillandsia_ species. Moreover, it is very valuable to discover the similarities and differences between the two botanical species _T. aeranthos_ and _T. bergeri_ and their hybrids, _T. aeranthos x T. bergeri_. In Figure 2, the first principal component (PC1) contributes to 27.91%, and the second principal component (PC2) contributes to 22.85% of the total variance in the volatile peak area data. Three distinct groups are identified: _T. aeranthos_ flowers are clustered together (in red), same for _T. bergeri_ flowers (in green) and the hybrids _T. aeranthos_ x _T. bergeri_ flowers (in blue). This shows a high degree of clustering of flowers belonging to the same species, thus suggesting a unique volatile profile for each of these three species and hybrids of _Tillandsia_. PC1 allows the partition of _T. aeranthos_ flowers from _T. bergeri_ and _T. aeranthos x T. bergeri_ flowers. This separation is due to the presence of sesquiterpenes in _T. aeranthos_ flowers contrary to _T. bergeri_ and the hybrids _T. aeranthos_ x _T. bergeri_. The higher presence of phenylpropanoids/benzenoids in the hybrids _T. aeranthos_ x _T. bergeri_ and _T. bergeri_ flowers allows the separation with _T. aeranthos_ (Figure 2). PC2 shows the difference of the floral emission on one side _T. aeranthos_ x _T. bergeri_, and on the other side _T. bergeri_ and _T. aeranthos_. This can be explained by the more intense presence of phenylpropanoids/benzenoids in _T.