On the Strength of Herbaceous Vascular Plant Stems

During the past 120 years researchers have tried to providean understanding of the relationship between the arrangementof stiffening tissue in the cross-section of plant stems andtheir mechanical integrity. The mechanical analysis of verticalstems of self-supporting plants has traditionally been concernedwith issues involving global and local stability of the stem,and with stresses developed due to wind loads. Plant stem tissue,considered as a material, is both heterogeneous and highly anisotropic,and this must be reflected in any characterization of its mechanicalbehaviour. This fact strongly influences the type of failurecriterion which should be applied for compressive failure ofthe stem subjected to loads causing bending. It is shown, here,that applying modern ideas as to the appropriate criteria forcompressive failure of fibre-reinforced composite materialscan influence how we assess the efficacy of various stelar arrangementsconcerning their ability to fulfill their mechanical function.Specifically, it is demonstrated that peripheral arrangementsof supporting tissue are, in some circumstances, less advantageousthan more uniform distributions of this tissue. Plant stems; stem bending; compressive strength; stelar types