Meeting Abstract
Spanish moss (Tillandsia usneoides (L.)) is a perennial flowering epiphyte with a large distribution across the moister parts of the Americas. Since it sustains itself with airborne particulates, rainfall, and photosynthesis, this epiphyte uses other plants as support to grow in clumps of hanging strands without great damage to the host. Despite its distribution and considerable number of growth and toxicity studies, there have been few explorations into its functional morphology. In this study, we describe the construction of the nodes (the point at which leaves sprout) and their internode connections that form individual Spanish moss strands. We used a light microscopical analysis to reconstruct the morphology from serial plastic sections (low viscosity GMA; Ladd Research Industries, Williston, VT) stained with toluidine blue. This analysis suggests that the strands function as purely tensile mechanisms in which the lignin core bears the strain and the nodes represent points where the breaking strength can be modulated. We used a material properties testing system (Imada, Northbrook, IL) to measure the breaking strength of the nodes (in our tests, the strands never broke within the internode) and then confirmed the mode of failure using subsequent histological reconstructions. The tensile core failed by tearing at a point of constriction within the node. The plant’s ability to modulate how and where it fragments may provide important insights into its unique mode of asexual reproduction as well as contribute to the mechanical understanding of ”break-away” tensile structures.
