## 1 Introduction  
Investigation into plant and flower scents represents an important field of modern research directed at special biological recognition theories. The scent of a flower is often a complex blend of secondary volatile metabolites, and together with colour and shape is considered to be the main signal attracting pollinators [1; 2; 3; 4], which in turn affect the reproductive performance of plants, their relationships with the environment and, therefore, their conservation (especially for rare and endangered species).  
In particular, the variety of shapes, colours and scents present in orchids is seldom found in other plant families. These characteristics contribute to the unique strategies used by orchids to attract pollinators. Many orchid species provide nectar, but other species are deceptive, so they attract pollinators in different ways, the most common strategies being mimicry of nectariferous flowers (e.g., _Orchis_, _Neotheea_, _Anacamptis_), sexual deception (e.g., _Ophrys_) and provision of shelter (e.g., _Serapias_) [5].  
In deceptive species attractiveness is very important to ensure reproductive success. For instance, orchid species of the genera _Ophrys_ and _Neotheea_ are known to produce complex bouquets of volatiles typically consisting of more than 100 chemical compounds [6; 7; 8]. The species belonging to these genera are all deceptive, but _Ophrys_ species use a sexual deception strategy, while _Neotheea_ is a food-deceptive genus [5]. The _Ophrys_ species attract and deceive their pollinators through an elaborate sexual mimicry that involves visual cues and volatile semiochemicals that mimic the pheromone of female insects. Food-deceptive orchids mimic rewarding species, some with specific models (e.g., _Disa_) others with flowers that have the typical characteristics of rewarding plants (_i.e._, nectar guides, spur, _etc._) (e.g., _Orchis_, _Neotheea_, _Anacamptis_) [9]. Moreover, _Ophrys_ species have evolved a high degree of pollinator specificity, while _Neotheea_ species are more generalist.  
Despite the importance of volatile compounds for the ecophysiological aspects of plant life, in the literature there are only a few publications on the characterization of orchids' volatile profiles [10; 11]. Flower, as well as whole plant, scents are conventionally analyzed by different methods, usually based on solvent extraction, steam distillation, or supercritical fluid extraction, that use destructive approaches. Moreover, the methods so far applied require that flowers or plants are collected, causing stress and mechanical damage to the plants thus altering their volatile profiles. Following these considerations soft extraction methods are preferred and HS-SPME was chosen to analyze the orchid samples. This technique has been developed for the fractionation of volatile organic compounds in several matrices, but can be also applied for the direct sampling of flower scents [10; 12; 13]. The method is rapid, solvent-free and inexpensive and reduces sampling stress; moreover it may be easily transferred into the field in order to investigate real _in vivo_ volatile emission.  
The aim of this study was to characterize, for the first time, the volatile organic compounds emitted, _in vivo_, by _Ophrys sphegodes_ Mill. subsp. _sphegodes_, _Ophrys bertolonii_ subsp. _benacensis_ ([PERSON]) [PERSON] and _Neotheea tridentata_ (Scop.) [PERSON]. [PERSON], [PERSON] & [PERSON]. [PERSON], three Italian populations of orchid species with different attraction strategies, sampling them _in situ_, in a non-disruptive way. Moreover, in order to define the most reliable sampling approach for improving knowledge regarding orchids' ecophysiological aspects, a comparison was made with the volatile profile obtained from flowering plant samples picked from the same orchid populations.