Meeting Abstract
Pitcher plants are a group of carnivorous plants that trap and digest prey in their cup-shaped leaves. The traps are passive and have several adaptations to attract and capture prey. In particular the temporarily-slippery peristome and a wax crystal-layer on the inside as well as the viscous fluid in the bottom of the pitcher facilitate the capturing and prevent an escape. In addition to those structures the species Nepenthes gracilis has a unique mechanism to capture prey, exploiting the impact energy of rain drops. It produces an increased amount of nectar on the underside of the lid directing prey there. Impacting raindrops accelerate the lid so that insects can’t grip to the wax-coated surface and fall into the pitcher. In comparison to those of other, non-specialised species the lid of N. gracilis does not bend and reaches a higher speed when accelerated by a raindrop. Previous studies showed that the high stiffness of the lid and a specialized friction-reducing wax-coating on its underside are both essential for its trapping function. Here we report further structural adaptations of the ‘neck’ region connecting the lid and the pitcher. We used micro-CT imaging to characterize the three-dimensional deformation during impact and investigate the role of structural reinforcement in the ‘neck’ region and pitcher rim, and estimate the reaction forces of the system. A comparison with the non-specialized pitcher plant Nepenthes rafflesiana confirmed the crucial role of the ‘neck’ region for the function of this exceptional trapping mechanism.
