The function of the wild carrot's dark central floret: attract, guide or deter?

Although Charles Darwin wrote about flower polymorphism in the wild carrot, Daucus carota , the function of the conspicuous central dark floret is still unclear. We used video recordings to evaluate the functional significance of the dark central floret as a short‐distance signal for insects landing on the umbels and analyzed the location of landing points, landing orientation and visit duration. These parameters, as well as insect attraction did not differ on umbels with and without a dark central floret. Hence, we found no evidence for the role of the dark central floret in the pollination of D. carota . Umbels with a dark central floret, however, were parasitized significantly less often by the gall midge Kiefferia pericarpiicola than umbels without a dark central floret. We propose that the dark central floret may play a role in reducing parasite infestation by mimicking an already present gall or deterring oviposition of the gall midge by other means.