Harvard University Division of Engineering and Applied Sciences Kavli Institute Wyss Institute School of Engineering and Applied Sciences Department of Organismic and Evolutionary Biology Harvard University
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The Venus Flytrap

The rapid closure of the carnivorous plant Venus flytrap (Dionaea muscipula) is one of the fastest motions (typically 100 ms) in the plant kingdom and led Darwin to describe the plant as "one of the most wonderful in the world". The closure is initiated by the mechanical stimulation of trigger hairs. Previous studies have focused on the biochemical response of the trigger hairs to stimuli and quantified the propagation of an action potential in the leaves. We complement these studies by considering the post-stimulation mechanical aspects of Venus flytrap closure. Using high-speed video imaging, non-invasive microscopy techniques and a simple theoretical model we show that the fast closure of the trap results from a snap-buckling instability. Our study illuminates an ingenious solution to scaling up movements in non-muscular engines and provides a general framework for understanding nastic motion in plants.

Superposition of the open and closed leaves of the Venus flytrap. The glass needle in the foreground was used to trigger the closure. Note that the leaves flip by almost turning inside out - similar to the flipping of a contact lens, plastic lid or the reversal of a torn tennis ball.
Illustrated versions of the leaves, showing the change in shape associated with closure of the leaf. Cutting a leaf parallel to the midrib and perpendicular to it shows that the snapping is in fact driven by just curvatures changes in the direction perpendicular to the midrib.
The dots were used to track the motion of the leaf as a function of time. Especially note how the curvature of the leaf changes so quickly. The glass rod on the right plays the role of the "fly".
Click here to see the high-resolution version. Courtesy of Forterre and Mahadevan.
Created by and courtesy of Farrah Shindler.
Click here to see a Quicktime movie of the
Venus flytrap in action.
Courtesy of Mahadevan et. al.

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   Last Updated: January 6, 2013

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