Force generation in the coiling tendrils ofPassiflora caerulea

Abstract

Tendrils of climbing plants coil along their length and thus form a striking helical spring and generate tensional forces. We have found that, for tendrils of the passion flowerPassiflora caerulea, the generated force lies in the range of 6-140 mN, which is sufficient to lash the plant tightly to its substrate. Further, we revealed that the generated force strongly correlates with the water status of the plant. By combining force measurements with anatomical investigations and dehydration-rehydration experiments on both entire tendril segments and isolated lignified tissues, we are able to propose a two-phasic principle of spring formation: First, during the free coiling phase, the tendril coiling is based on the active contraction of a fiber ribbon in interaction with the surrounding parenchyma as resistance layer. Second, in a stabilization phase, the entire center of the coiled tendril lignifies, stiffening the spring and securing its function independent of hydration status.

Cross-Sectional 4D-Printing: Upscaling Self-Shaping Structures with Differentiated Material Properties Inspired by the Large-Flowered Butterwort (Pinguicula grandiflora)

“…Much of the existing literature on self-shaping is inspired by plant motions [ 13 , 14 , 15 , 16 ], which are driven by slow water displacement processes between cells and tissues, including reversible turgor changes, hygroscopic reactions or irreversible growth, and/or the rapid release of elastic energy (prestress) previously stored in the motile structures [ 17 ]. Plants are able to perform a variety of motions based on deformation processes, such as bending [ 18 ], twisting [ 19 ], coiling [ 20 ], snap through [ 21 ], and explosive bursting [ 22 ].…”