###### Abstract  
VOCs emitted by flowers play an important role in plant ecology. In the past few years, the _Tillandsia_ genus has been scarcely studied according to the VOCs emitted by flowers. Hence, we decided to enlarge the VOCs composition study already undergone in our laboratory on fragment 3 _Tillandsia_ species to 12 unscented and 2 faint-scented _Tillandsia_ species and hybrids. The headspace solid phase microextraction (HS-SPME) coupled with gas chromatography combined with the mass spectrometry (GC-MS) method was used to explore the chemical diversity of the VOCs. This study allowed the identification of 65 VOCs among the 14 species and between 6 to 25 compounds were identified in each of the species. The aromatic profile of 10 of the species and hybrids are similar to each other's and show 8 predominant compounds: benzaldehyde, benzacetaldehyde, hexanol, hexanol, hexanal, heptanal, octanal, nonanal, andfuran-2-pentyl. Some specific compounds are present only in some unique species such as trans-calamenene, \(\alpha\)-muuronle, and \(\alpha\)-guaiene trans-\(\beta\)-bergamotene. The two faint-scented species studied present an original aromatic profile with a high number of monoterenes or phenylpropanoids/benzoids. Our studies allow a better understanding of the ecological role and function of these VOCs in the interactions between these plants with their environment. Tillandsia; headspace solid phase microextraction (HS-SPME); gas chromatography-mass spectrometry (GC-MS); scentless flowers; faint-scented flowers; volatile organic compounds (VOCs); PCA analysis; heatmap +
Footnote †: journal: _Metabolites_  
these classes of compounds possess their own biosynthetic pathways such as the acetate pathway for fatty acids derivatives or the mevalonic acid pathway for sesquiterpenoids. For example, phenylpropanoids, benzenoids and their derivatives are biosynthesized through the shikimate pathway [11]. Generally, the VOCs emitted by flower plants have a low molecular weight [12]. Concerning the non-fragrant plants, some species can be scentless for human beings while other species might have a subtle scent only detected by some people. Non-fragrant flowers also emit different VOCs such as aliphatic aldehydes, aliphatic alcohols, and phenylpropanoids/benzenoids [13; 14]. VOCs' role in plants is essential and varied from pollinator attraction to defense against predators and growth [4; 15]. Plants, through the VOCs emitted by flowers, are in constant interaction with their environment such as micro-organisms, herbivorous insects, pollinators, or plants between themselves [11]. It has been shown that comparable visual and olfactory signals were due to the plant pollination by close pollinators [16]. However, in a mix composed of major and minor VOCs, the most abundant compounds do not determine the trend of the response [11]. Studies have shown that VOCs of non-fragrant flowers also attract pollinators [17; 18]. Moreover, recent studies indicate that scentless Australian orchids emit volatile organic compounds highly attractive to the male wasp [19; 20]. A study on _Tillandsia macropetala_ was carried out in 2014 by [PERSON] et al. and showed a correlation between the presence of volatile compounds and the pollination of bats [21]. Nevertheless, _T. macropetala_ has been removed from the _Tillandsia_ genus in 2016. Finally, the role of floral scent not has only an ecological role, but also an aesthetic character of ornamental plants [22]. Gas chromatography combined with a mass spectrometer (GC-MS) is the most commonly used technique to identify VOCs in flowers. To isolate them, different techniques can be used, each one with their advantages and drawbacks such as large quantities of solvent used [15]. The steam distillation, the solvent extraction, and the headspace solid phase microextraction (HS-SPME) are the most common techniques to extract and isolate volatile compounds from a plant [23]. Nowadays, HS-SPME is widely used to extract and identify volatile compounds from flowers [24].