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Editors-in-Chief: Lloyd A. Donaldson and Marcelo R. Pace
2019 Journal Impact Factor: 1.627
5-year Impact Factor: 1.966

The IAWA Journal is an international quarterly periodical publishing original papers and review articles on any subject related with the microscope structure of wood and bark of stems and roots of woody plants (including palms and bamboo). Apart from anatomy per se, subjects at the interface of microstructure and developmental genetics, systematics, paleobotany, archaeology, tree biology, ecology, forestry, structure property relations of timber, biomechanics, wood identification, etc. are welcomed.

For more information about the International Association of Wood Anatomists and the IAWA Journal, please visit the IAWA website.

Online submission: Articles for publication in IAWA Journal can be submitted online through Editorial Manager, please click here. As of July 1st 2017, full colour images and figures are published free of charge.

2017 Impact Factor: 1.903
5 Year Impact Factor: 1.671

For more information about the International Association of Wood Anatomists and the IAWA Journal, please visit the IAWA website.

Online submission: Articles for publication in IAWA Journal can be submitted online through Editorial Manager, please click here. As of July 1st 2017, full colour images and figures are published free of charge.

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Stem ontogeny and structure of two neotropical twining vines of the genus Callaeum are described. Secondary growth in Callaeum begins with a typical regular cambium that gradually becomes lobed as a result of variation in xylem and phloem production rates in certain portions of the stem aligned with stem orthostichies. As development progresses, lignified ray cells of the initially formed secondary xylem detach on one side from the adjacent tissues, forming a natural fracture that induces the proliferation of both ray and axial nonlignified parenchyma. At the same time, parenchyma proliferation takes place around the pith margin and generates a ring of radially arranged parenchyma cells. The parenchyma generated in this process (here termed disruptive parenchyma) keeps dividing throughout stem development. As growth continues, the parenchyma finally cleaves the lignified axial parts of the vascular system into several isolated fragments of different sizes. Each fragment consists of xylem, phloem and vascular cambium and is immersed in a ground matrix of disruptive parenchyma. The cambium present in each fragment divides anticlinally to almost encircle each entire fragment and maintains its regular activity by producing xylem to the centre of the fragment and phloem to the periphery. Additionally, new cambia arise within the disruptive parenchyma and produce xylem and phloem in various polarities, such as xylem to the inside and phloem to the outside of the stem, or perpendicularly to the original cambium. Unlike the very distinctive stem anatomical architecture resulting from this cambial variant in Callaeum, its secondary xylem and phloem exhibit features typical of lianas. These features include very wide conducting cells, abundant axial parenchyma, high and heterocellular rays and gelatinous fibres.

In: IAWA Journal

A new method is presented to prepare anatomical slides of plant materials including a combination of soft and hard tissues, such as stems with cambial variants, arboreal monocotyledons, and tree bark. The method integrates previous techniques aimed at softening the samples and making them thereby more homogeneous, with the use of anti-tearing polystyrene foam solution. In addition, we suggest two other alternatives to protect the sections from tearing: adhesive tape and/or Mayer’s albumin adhesive, both combined with the polystyrene foam solution. This solution is cheap and easy to make by dissolving any packaging polystyrene in butyl acetate. It is applied before each section is cut on a sliding microtome and ensures that all the tissues in the section will hold together. This novel microtechnical procedure will facilitate the study of heterogeneous plant portions, as shown in some illustrated examples.

In: IAWA Journal

ABSTRACT

Good anatomical sections can only be obtained with a perfectly sharp knife. Permanent steel microtome knives are present in numerous plant anatomy labs and they yield excellent results, with the only caveat that they need to be re-sharpened after use. Automatic knife sharpeners have been especially designed for this purpose, but they require abrasives in their use, which may be expensive and hard to obtain. Here we describe and illustrate in detail an inexpensive, fast, widely accessible technique to sharpen permanent microtome knives using different sandpaper grits. Knives sharpened with this technique have already been in use for over a decade and are suitable for all types of botanical specimens both embedded and unembedded.

In: IAWA Journal

ABSTRACT

Covariation amongst wood traits along the stem axis is important to maintain hydraulic integrity ensuring sufficient sap flow to the canopy. Here, we test how wood traits (co)vary along the trunk and whether two seasonally dry Brazilian habitats (cerrado and caatinga) influence this variation in two co-occurring species, Tocoyena formosa (Rubiaceae) and Tabebuia aurea (Bignoniaceae). The samples were collected at five heights along the main trunk of three individuals per species in both sites. We used light, scanning and transmission electron microscopy to observe the wood traits. Out of 13 wood traits, nine show relationships with sampling height: eight traits predict height in T. formosa and five in T. aurea. Contrastingly, only three traits show differences between sites and only for T. formosa. The intratrunk wood variation is reflected by the hydraulically weighted vessel diameter showing a curvilinear relationship, disagreeing with the prediction of a continuous vessel widening from tip to base. In both species, the largest vessels are linked to the thinnest intervessel pit membranes. Wood density increases basipetally for both species, being site-dependent and correlated with vessel traits in T. formosa, and site-independent and determined by fiber wall thickness in T. aurea. Furthermore, the functional role of rays was found to be different for each species, and may be related to the marked difference in ray composition. In conclusion, both species show a unique adaptation to deal with height-related constraints using species-specific co-variation amongst wood traits, while site does not contribute much to the wood variation.

In: IAWA Journal

Abstract

The liana genus Paullinia L. is one of the most speciose in the neotropics and is unusual in its diversity of stem macromorphologies and cambial conformations. These so-called “vascular cambial variants” are morphologically disparate, evolutionarily labile, and are implicated in injury repair and flexibility. In this study, we explore at the finer scale how wood anatomy translates into functions related to the climbing habit. We present the wood anatomy of Paullinia and discuss the functional implications of key anatomical features. Wood anatomy characters were surveyed for 21 Paullinia species through detailed anatomical study. Paullinia woods have dimorphic vessels, rays of two size classes, and both septate and non-septate fibers. Fibriform vessels, fusiform axial parenchyma, and elements morphologically intermediate between fibers and axial parenchyma were observed. Prismatic crystals are common in the axial and/or ray parenchyma, and laticifers are present in the cortex and/or the early-formed secondary phloem. Some features appear as unique to Paullinia or the Sapindaceae, such as the paucity of axial parenchyma and the abundance of starch storing fibers. Although many features are conserved across the genus, the Paullinia wood anatomy converges on several features of the liana-specific functional anatomy expressed across distantly related lianas, demonstrating an example of convergent evolution. Hence, the conservation of wood anatomy in Paullinia suggests a combination of phylogenetic constraint as a member of Sapindaceae and functional constraint from the liana habit.

In: IAWA Journal