The Physics of Plant Predation: Unfolding the Mechanics behind Drosera capensis Leaf Movement

The cape sundew (Drosera capensis) captures prey using a sticky mucilage that coats its leaves, which then curl or fold to further entrap prey and facilitate digestion. While other carnivorous plants have been extensively studied, the diversity of responses and the underlying physical mechanisms of leaf movement in Drosera remain poorly quantified. Here, we modeled the folding motion of Drosera capensis leaves to analyze their steady-state positions and folding dynamics, and we compared our model results to time-lapse photography data taken in our lab. We find that prey contact induces local curvature formation. By varying placement and amount of food stimulus, we explore and subsequently model a large phase-space of final conformations and dynamics produced by Drosera capensis leaves. We further image the underlying cell shape changes that lead to macroscopic curvature induction to develop a full, mechanistic understanding of the prey trapping behavior of Drosera capensis. Our computational models suggest that the folding behavior may be driven by a differential growth pattern across the leaf surface. These findings establish a physical framework for understanding the thigmotropic dynamics of Drosera capensis and may inform future bio-inspired design.