Mechanics of plant tendrils

Tendrils of grapevine (vitis vinifera)

 

Pea (Pisum sativum) tendril

Red bryony (Bryonia dioica)

Red bryony (Bryonia dioica)

a) Measurement of the traction exerted by the tendril while making its twist as a function of time. Shaded are time intervals when the traction force increased; b) Numerical simulation: Three views of a static configuration for a beam (circular cross section) clamped at the two ends. The surface color indicate the mechanical torque inside the system. The yellow curve at the left end enables to visualize the relaxed shape, and so the rest curvature. A 45° rotation is imposed at the right end. This configuration shows the beginning of a “perversion” linking two phases (of opposite helicity).
Modelling using Kirchhoff equations and numerics: Plot of the Writhe, Wras a function of the rest curvature kof the beam. The beam, of circular cross section, is clamped at the two ends, and a 45 degree rotation is imposed at the right end. The yellow ribbon indicates the “relaxed” shape of the beam, and allow to visualize the rest curvature of the beam.
Measurement of the traction exerted by the tendril while making its twist as a function of time