Interspecific variation in defensive flower closure of Drosera (Droseraceae) is related to the herbivory pressure.

This article investigates interspecific variation in rapid flower closure in two closely related carnivorous plant species, Drosera rotundifolia and Drosera tokaiensis, focusing on its ecological and evolutionary significance as a defense against herbivory by the specialist caterpillar Buckleria paludum. The study finds that D. tokaiensis exhibits faster flower closure than D. rotundifolia, which correlates with more effective protection of ovules from herbivore damage. Field surveys indicate that D. tokaiensis experiences higher herbivory pressure, likely due to its preference for drier microhabitats that facilitate caterpillar movement, whereas D. rotundifolia inhabits wetter areas with lower herbivory. No significant ecological or physiological costs were detected for rapid flower closure in either species, supporting the hypothesis that variation in closure speed has evolved in response to differing herbivory pressures.