Density-dependent Stiffness in Petiole Biomechanics

Abstract

Morphological features of plants vary with increasing size. This relationship between different physical characteristics and size is referred to as allometry. Recently allometric research focused on plants and in particular plant leaves due to their importance in nutrient flow and gas exchange. Allometric plant research aims to enhance our understanding of the ontogeny of plants and offers a tool for ecological modeling. Previous allometric models have glanced over the influence of biomechanics on leaf form and function. This research will test if density-dependent stiffness of petioles is variable or if it scales with leaf mass. In order to test the variance of stiffness in leaf petioles, Young s modulus (E) was measured by modeling the petioles as simply loaded beams. Young s modulus was shown to vary among different species, even those of the same genus. Density-dependent stiffness varied with leaf size for some herbaceous species but not for other woody tree species. Future research should investigate the biomechanical role of a possible redistribution of structural tissue and how this rearrangement would affects petiole stiffness and overall petiole function.