Phytochemical data parallel morpho-colorimetric variation in Polygala flavescens DC.
Phytochemical data, integrated with other sources of information, represent a valuable tool helping to solve different kinds of taxonomic problems in plant systematics. In the present study, a comparative investigation, in order to clarify the systematic relationships of the three subspecies currently recognized within the Italian endemic Polygala flavescens, was carried out. Preliminarily, a morphometric and colorimetric analysis, in order to test the degree of morphological distinctiveness among the taxa, was performed. Then, a phytochemical analysis based both on volatile and non-volatile compounds was obtained. Concerning the morpho-colorimetric analysis, our results confirm most of the characters as useful to discriminate the three subspecies. In addition, some volatile and non-volatile compounds are good taxonomic markers. Morpho-colorimetric variation is clearly paralleled by phytochemical results, confirming the value of this kind of data to infer relationships in plant systematics. Based on these results, we support a taxonomic treatment at subspecific level for the involved taxa. Finally, based on the most significant morphological characters, a revision of herbarium specimens allowed to redefine the distribution pattern of the three subspecies. Accordingly, the range of P. flavescens subsp. maremmana is limited to Mt. Argentario (southern Tuscany) only. A key is also reported for the identification of the three subspecies.