title: Biomechanical tactics of chiral growth in emergent aquatic macrophytes.
abstract: Through natural selection, many plant organs have evolved optimal morphologies at different length scales. However, the biomechanical strategies for different plant species to optimize their organ structures remain unclear. Here, we investigate several species of aquatic macrophytes living in the same natural environment but adopting distinctly different twisting chiral morphologies. To reveal the principle of chiral growth in these plants, we performed systematic observations and measurements of morphologies, multiscale structures, and mechanical properties of their slender emergent stalks or leaves. Theoretical modeling of pre-twisted beams in bending and buckling indicates that the different growth tactics of the plants can be strongly correlated with their biomechanical functions. It is shown that the twisting chirality of aquatic macrophytes can significantly improve their survivability against failure under both internal and external loads. The theoretical predictions for different chiral configurations are in excellent agreement with experimental measurements.
authors.affiliation: 1] AML &CAMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China [2] Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Zi-Long
authors.initials: ZL
authors.lastname: Zhao
authors.affiliation: AML &CAMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Hong-Ping
authors.initials: HP
authors.lastname: Zhao
authors.affiliation: AML &CAMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Bing-Wei
authors.initials: BW
authors.lastname: Li
authors.affiliation: AML &CAMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Ben-Dian
authors.initials: BD
authors.lastname: Nie
authors.affiliation: 1] AML &CAMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China [2] Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Xi-Qiao
authors.initials: XQ
authors.lastname: Feng
authors.affiliation: 1] AML &CAMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China [2] School of Engineering, Brown University, Providence, RI 02912, USA.
authors.forename: Huajian
authors.initials: H
authors.lastname: Gao