"Our work complements prior research," says Lakshminarayanan Mahadevan, Gordon McKay Professor of Applied Mathematics and Mechanics in Harvard University's Division of Engineering and Applied Sciences and affiliate in the Department of Organismic and Evolutionary Biology in Harvard's Faculty of Arts and Sciences. "In addition to looking at biochemical events, we looked at what happened after the plant was stimulated and found that the rapid closing is due to a 'snap-buckling instability' that the plant itself controls."
To trap its prey, the carnivorous plant relies on both an active biochemical and a passive elastic process, say Mahadevan and former students and postdocs Yol Forterre, Jan M. Skotheim, and Jacques Dumais. When an insect brushes up against a hair trigger, the plant responds by moving water to actively change the curvature of its leaves. While exactly how the water is moved is not completely understood, the scientists observed that the deformation of the leaves, once stimulated, provided the means by which elastic energy was stored and released, creating a simple yet effective jaw-like movement.
"In essence, a leaf stretches until reaching a point of instability where it can no longer maintain the strain," Mahadevan says. "Like releasing a reversed plastic lid or part of a cut tennis ball, each leaf folds back in on itself, and in the process of returning to its original shape, ensnares the victim in the middle. The hydrated nature of the leaf quickly dampens the vibrations caused by the movement, so the
Contact: Steve Bradt