Octave_Structure.mat from Fluttering of growing leaves as a way to reach flatness: experimental evidence on <i>Persea americana</i>

Simple leaves show unexpected growth motions: the midrib of the leaves swings periodically in association with buckling events of the leaf blade, giving the impression that the leaves are fluttering. The quantitative kinematic analysis of this motion gives information about the respective growth between the main vein and the lamina. Our three-dimensional reconstruction, in the case of the avocado tree leaf, shows that the conductor of the motion is the midrib, presenting continuous oscillations and inducing buckling events on the blade. The variations of the folding angle of the leaf show that the lamina is not passive: it responds to the deformation induced by the connection to the midrib to reach a globally flat state. We model this movement as an asymmetric growth of the midrib, directing an inhomogeneous growth of the lamina, suggesting how the transition from the folded state to the flat state is mechanically organized.简单叶片展现出出人意料的生长运动：叶中脉（midrib）会伴随叶身（leaf blade）的屈曲（buckling）事件周期性摆动，令叶片看起来仿佛正在轻舞飞扬。对该运动开展定量运动学分析，可获取主脉与叶片（lamina）间的相对生长信息。我们针对牛油果树叶开展的三维重建结果表明，该运动的驱动源为叶中脉：其持续产生振荡，并在叶身引发屈曲事件。叶片折叠角的变化规律显示，叶片并非被动受力体：它会响应由中脉连接所引发的形变，以达成整体平整的状态。我们将该运动建模为叶中脉的不对称生长，该生长驱动叶片产生非均匀生长，由此揭示了叶片从折叠状态向平整状态转变的力学组织机制。