The pollination syndrome of parasitic plants depends on the environment

Plants interact ubiquitously with organisms surrounding them through chemical communication, for example through the emission of volatile organic compounds (VOCs) by flowers, to attract pollinators. To attain specificity in this relationship, plants may evolve different VOCs for different pollinators. In the present study we investigated the flower VOCs of the root parasitic butterbur broomrape (Orobanche flava), which parasitizes several different Petasites spp. at geographically different locations in Slovakia, and analyzed the corresponding community of pollinators, some of which have never been reported before for O. flava. There were intriguing differences in floral scent phenotype as well as pollinator community composition between the locations, suggesting the existence of different ecotypes of O. flava. We discuss this variation in floral VOCs and compare the results with other studies investigating intraspecific variability in floral scent. The differences in floral scent chemistry and corresponding pollinator species between broomrapes in different regions suggest pollinator-mediated selection across the geographical distribution of this parasitic plant species.