Secondary pollen presentation in Cuban bat pollinated Lobelia: precise deposition of pollen and mechanical species isolation
Koch, Corinna U. von Helversen
published: Dec 19, 2006
The species-rich genus Lobelia has been studied since nearly one and a half century with respect to its pollination biology. The genus is well known for its special way of secondary pollen presentation, which has been described as a "pump and piston" or as a "noodle squeezer" mechanism, as the style pushes the pollen out of the tip of a tube that is formed by the fused stamens.(1) We show that several species of Lobelia in Cuba are pollinated by bats, what adds a new and unexpected pollination mode to the known pollination systems of the genus.(2) With help of Infra-Red-videos, recorded in the field, we document a very precise deposition of the pollen onto small areas of the fur of the bat, in one species (Lobelia oxyphylla) behind the bat's nose-leaf, in another species (L. imberbis) between the ears, and in a third species (L. assurgens) at the middle of the bat's front. These areas don't overlap and thus pollen deposition may serve as a mechanical isolating mechanism.(3) The mechanism of pollen deposition is "pollinator powered": By the pressure exerted by the bat's tongue, the staminal column is not only bent down, but also is the style shifted within the staminal tube, so that an exact dosage of pollen can be delivered onto the bat's fur.