title: Functional morphology and biomechanics of branch-stem junctions in columnar cacti.
abstract: Branching in columnar cacti features morphological and anatomical characteristics specific to the subfamily Cactoideae. The most conspicuous features are the pronounced constrictions at the branch-stem junctions, which are also present in the lignified vascular structures within the succulent cortex. Based on finite-element analyses of ramification models, we demonstrate that these indentations in the region of high flexural and torsional stresses are not regions of structural weakness (e.g. allowing vegetative propagation). On the contrary, they can be regarded as anatomical adaptations to increase the stability by fine-tuning the stress state and stress directions in the junction along prevalent fibre directions. Biomimetic adaptations improving the functionality of ramifications in technical components, inspired, in particular, by the fine-tuned geometrical shape and arrangement of lignified strengthening tissues of biological role models, might contribute to the development of alternative concepts for branched fibre-reinforced composite structures within a limited design space.
authors.affiliation: Institute for Botany, Botanic Garden, Faculty of Science, Technische Universität Dresden, , Zellescher Weg 20b, 01062 Dresden, Germany, Plant Biomechanics Group, Botanic Garden, Faculty of Biology, University of Freiburg, , Schänzlestraße 1, 79104 Freiburg, Germany.
authors.forename: Hannes
authors.initials: H
authors.lastname: Schwager
authors.forename: Tom
authors.initials: T
authors.lastname: Masselter
authors.forename: Thomas
authors.initials: T
authors.lastname: Speck
authors.forename: Christoph
authors.initials: C
authors.lastname: Neinhuis
mesh_terms: D000220:Adaptation, Biological; D001696:Biomechanical Phenomena; D029421:Cactaceae / Q000033:anatomy & histology* / Q000502:physiology*; D020342:Finite Element Analysis; D008954:Models, Biological; D018547:Plant Stems / Q000033:anatomy & histology / Q000502:physiology; D013045:Species Specificity
keywords: biomimetics; branching; columnar cacti; finite-element analysis; functional anatomy