Variations in dicot wood anatomy: A global analysis based on the insidewood database

Abstract

Information from the Inside Wood database (5,663 descriptions) was used to determine the relative abundance of selected IAWA Hardwood List Features, for the whole world and for the broad geographic regions used in the IAWA List. Features that occur in more than 75 % of the records are: growth ring boundaries indistinct or absent, diffuse porosity, exclusively simple perforation plates, alternate intervessel pitting, and non-septate fibers. The geographic distribution of vessel element features found in this study is consistent with previous studies: ring porosity is a Northern Hemisphere adaptation; numerous, narrow, short vessel elements are more common in temperate regions than in tropical regions. Element size is related to habit, with few wide vessels being a syndrome that is virtually absent from shrubs and small trees. The co-occurrence of selected features, ones that earlier have been suggested to be correlated, was examined; e.g., tangential vessel arrangement and ring porosity, rare axial parenchyma and septate fibers, tracheids and exclusively solitary vessels that are of medium to wide diameter. Axial parenchyma features show geographic variation, with aliform to confluent parenchyma and bands more than 3 cells wide being primarily tropical in occurrence. Storied rays, crystals, and silica bodies are more common in the tropics than in the temperate Northern Hemisphere. For ray features, geographic patterns are less apparent. In Australia, incidences of some features (vestured pits, solitary vessels, radial/diagonal vessel arrangement) are influenced by the Myrtaceae being a major component of the flora. This paper is but a general overview. Information from the Inside Wood database when combined with detailed information on ecological and geographical distributions of species, and subjected to more robust statistical analyses can be used to address a variety of questions on the evolution of wood structure and the ecological and phylogenetic significance of suites of features.