Static and dynamic properties of pre-twisted leaves and stalks with varying chiral morphologies

The mechanical properties and biological functions of tissues and organs in plants are closely related to their structural forms. In this study, we have performed systematic measurements and found that the leaves and stalks of several species of emergent plants exhibit morphologies of twisting and gradient chirality. Inspired by the experimental findings, we investigate, both theoretically and numerically, the static bending and vibrational properties of these plant organs. By modeling the leaves and stalks as pre-twisted cantilever beams, the effects of the cross-sectional geometry, loading condition, handedness perversion, twisting configuration, and morphological gradient, on their mechanical behavior are evaluated. Our analysis reveals that both static and dynamic responses of the beams can be easily tuned by changing their structural parameters. For any part of the beams, its chiral morphology has more significant influences on the overall structural performance (e.g., bending stiffness and natural frequencies) if it is closer to the clamped end. This work not only deepens our understanding of the structure–property–function interrelations of chiral plants, but also holds potential applications in the bio-inspired design of innovative devices and structures.