Rainwater in cupulate bracts repels seed herbivores in a bumblebee-pollinated alpine flower

The discovery of new adaptations of organisms to various environments always reminds us how little we know about nature. For example, rainwater surrounding sexual organs has been noted in several flowering plant groups. In a new study published in AoB PLANTS, Sun and Huang used a bumblebee-pollinated alpine flower, Pedicularis rex (Orobanchaceae), which has cup-like bracts holding rainwater and is endemic to southwest China, as an experimental model to examine whether the water-filled cupulate bracts function to deter nectar robbers and/or seed herbivores. They found that neither nectar robbers nor legitimate pollinators discriminated water-drained flowers, but seed predation significantly increased in drained flowers, suggesting that water-filled bracts help protect the flowers from seed herbivores.