Floral scent analysis in Hieracium subgenus Pilosella and its taxonomical implications

Species-rich Hieracium subgen. Pilosella is well-known for a high degree of endemism and infra-specific differentiation including many subspecies (“microspecies”) of very restricted distribution. In Hieracium subgen. Pilosella floral scents of 27 predominantly Bavarian species, mostly of Hieracium calodon, H. zizianum and H. densiflorum, are investigated here. Floral scent compositions were studied by GC-MS analysis of dynamic headspace samples. Altogether, 56 floral scent compounds were identified, mainly benzenoids, fatty acid derivatives, monoterpenes, homoterpenes and sesquiterpenes. The chemical patterns were found to be taxon-specific and are thus of taxonomical value. The data support some rearrangements at subspecific level, such as the inclusion of H. bauhini subsp. hispidissimum in H. densiflorum. These rearrangements are supported by morphological data. The traditional species concepts, however, are mostly corroborated by our scent data.