A sound strategy for pollination

Plants gain an advantage in attracting pollinators if they stand out from the crowd. And so, many plants have evolved flowers with spectacular coloration or enticing scents. Now Ralph Simon (University of Ulm) and colleagues report that the Cuban vine Marcgravia evenia uses a novel trick—based on acoustics rather than visual or olfactory effects—to attract its pollinating bats. Just above its purple flowers, M. evenia presents specialized concave leaves to the foraging bat. The leaves' spherical-cap geometry enables them to return a strong and consistent echolocation reflection over a wide angular range. Thus, as the bat flies around in the vicinity of M. evenia, the plant's steady signal is prominent amongst the random din of echoes from surrounding foliage. To check if M. evenia's specialized leaf really does assist bats in finding the vine, Simon and colleagues hid a sugar-water feeder in artificial foliage and, in various trials, accompanied it with a replica of M. evenia's concave leaf, a replica of the vine's nonspecialized leaf, or nothing at all. Bats consistently found the feeder more quickly when the concave leaf was present. It's hard to imagine, write the authors, that the specialized leaves of M. evenia can have any evolutionary advantage other than attracting pollinators. (R. Simon et al., Science 333, 631, 2011; image courtesy of Corinna U. Koch.)—Steven K. Blau