Pollination Adaptation in Pedicularis lanceolata

Cinematographic, stereophotographic, and visual observations have revealed that the zygomorphic, nectarless flower of Pedicularis lanceolata Michx. is pollinated in northeastern Ohio by pollen-foraging workers of three Bombus species. Foragers hang inverted from the asymmetrical corolla and remove pollen with their front and middle legs from anthers concealed by the galea. The stigma contacts pollen deposited especially on the median portion of the forager's first abdominal sterilite. Insect exclosures and pollinator collections demonstrated the obligate pollination dependence of the flower on Bombus workers. Of 152 corbicular pollen loads from workers foraging on P. lanceolata, Gentiana andrewsii, Prunella vulgaris and five composite species in the same habitat, 84.2% contained P. lanceolata pollen; 75.8% of the latter contained P. lanceolata pollen exclusively. Possible coadaptive relationships of Pedicularis flowers and pollinators are discussed.