It's the first time such a feature has been discovered in plants, which mostly rely on flashy colors to attract pollinating insects. But hundreds of plant species use bats to pollinate, and researchers are still teasing out how the flying mammals home in on the plants.

In the lab, scientists noticed that Pallas's long-tongued bats excelled at finding hollow hemisphere shapes hidden among artificial leaves.

Study co-author Ralph Simon of Germany's University of Ulm then saw a picture of a Cuban plant called Marcgravia evenia. He "noticed the dish-shaped leaf above the flower, and thought, Wow, that's like a hemisphere ... that must be a signal for bats."

Study co-author Marc Holdereid of the U.K.'s