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A photo montage of a Marcgravia evenia flower, with its nectaries below and dish-shaped leaf above, along with a Glossophaga soricina bat (image courtesy of Ralph Mangelsdorff and Ralph Simon)

Flowers have evolved many strategies for attracting pollinators—bright colors, guiding patterns, interesting scents, brilliant mimicry. The Cuban rainforest vine Marcgravia evenia has a different strategy, though. Scientists have found that the vine has one or two specially shaped leaves hanging near its flowers that act as a bat signal, luring these flying mammals. The bats get a meal, and the flowers get pollinated. (The study appears in this week’s Science.)

The leaves have a concave shape, somewhat like a dish reflector. When researchers sent a sonar signal towards such a leaf, they found that they received back strong echoes that a bat would find easy to identify. The scientists then trained nectar-feeding Glossophaga soricina bats to find a small feeder among foliage; when they placed a replica of the special leaf near the feeder, the bats were able to find it twice as fast.

Having such a leaf does have a downside for the plant—it isn’t as well-suited for photosynthesis as more traditional leaves on the vine and thus creates less energy for the plant. But the scientists argue in their paper that “these costs are outweighed by the benefits of more efficient pollinator attraction.” In other words, the plant’s need for sex is greater than its need for more food.

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